bluuebunny/crossref_metadata_2025 huggingface dataset:
Shock-wave solutions in two-layer channel flow. II. Linear and nonlinear stability
Authors: Mavromoustaki A. , Matar O. K. , Craster R. V.
Published: November 2011

We investigate the flow of two immiscible fluids in an inclined channel, building on the work presented in Part I of this study. In this paper, we examine the stability of the flow to spanwise perturbations in both the linear and nonlinear regimes. The evolution equation governing the interfacial dynamics, derived using lubrication theory in Part I, is linearised to study the effect of system parameters on the linear stability of the interface. A transient growth analysis of the linearised equation is carried out with no-flux conditions in the spanwise direction. The results of this analysis reveal that increasing the density and/or the viscosity of the upper layer, and/or increasing the counter-current nature of the flow configuration exerts a stabilising influence. Inspection of the flow profiles indicates that single Lax-shocks and the trailing Lax-shocks in Lax-undercompressive double-shocks are unstable to finger formation; undercompressive shocks and rarefaction waves are stable. In unstably stratified cases, increasing the channel inclination away from verticality, such that a denser upper layer overhangs a less dense lower one, is found to be destabilising. These results are used to guide our transient numerical simulations aimed at studying the nonlinear development of fingering phenomena.
Dynamics of microcapsules in oscillating shear flow
Authors: Zhao Mengye , Bagchi Prosenjit
Published: November 2011

We present a three-dimensional numerical study on the dynamics of deformable capsules in sinusoidally oscillating shear flow. We consider capsules of spherical and oblate spheroid resting shapes. For spherical resting shapes, we find an identical deformation response during positive and negative vorticities. However, the deformation response becomes unequal and shows complex behavior for nonspherical resting shapes. The average elongation is higher in the retarding phase of the shear flow than in the accelerating phase. Primarily two types of dynamics are observed for nonspherical shapes: a clockwise/counter-clockwise swinging motion in response to the altering flow direction that occurs at both high and low values of shear rate amplitudes, and a continuous/unidirectional tumbling motion that occurs at intermediate values. The unidirectional tumbling motion occurs despite the fact that the time-average vorticity is zero. Such a tumbling motion is accompanied by a continuous tank-treading motion of the membrane in the opposite direction. We obtain phase diagram that shows existence of two critical shear rates and two oscillation frequencies. The unidirectional tumbling motion occurs in the intermediate range, and the clockwise/counter-clockwise swinging motion occurs otherwise. We also find that the dynamics is highly sensitive to the initial condition. A swinging is generally observed when the capsule is released aligned with the extensional or compressional axis of the shear flow, and a tumbling is observed otherwise. These results suggest the possibility of chaotic behavior of cells in time-dependent flows. We provide explanations of such complex dynamics by analyzing the coupling between the shape and angular oscillation and the imposed flow oscillation.
Non-equilibrium spin-boson model: Counting statistics and the heat exchange fluctuation theorem
Authors: Nicolin Lena , Segal Dvira
Published: November 2011

We focus on the non-equilibrium two-bath spin-boson model, a toy model for examining quantum thermal transport in many-body open systems. Describing the dynamics within the noninteracting-blip approximation equations, applicable, e.g., in the strong system-bath coupling limit and/or at high temperatures, we derive expressions for the cumulant generating function in both the Markovian and non-Markovian limits by energy-resolving the quantum master equation of the subsystem. For a Markovian bath, we readily demonstrate the validity of a steady-state heat exchange fluctuation theorem. In the non-Markovian limit a “weaker” symmetry relation generally holds, a general outcome of microreversibility. We discuss the reduction of this symmetry relation to the universal steady-state fluctuation theorem. Using the cumulant generating function, an analytic expression for the heat current is obtained. Our results establish the validity of the steady-state heat exchange fluctuation theorem in quantum systems with strong system-bath interactions. From the practical point of view, this study provides tools for exploring transport characteristics of the two-bath spin-boson model, a prototype for a nonlinear thermal conductor.
Vibronic coupling in the A2Π and B2Σ+ electronic states of the NCS radical
Authors: Tarroni Riccardo
Published: November 2011

The spin-rovibronic energy levels of the A2Π and B2Σ+ electronic states of thiocyanate radical have been calculated variationally, using high-level ab initio coupled diabatic potential energy surfaces. Computations up to J = 7/2 have been performed, obtaining all levels with K ⩽ 3 (\documentclass[12pt]{minimal}\begin{document}$\Sigma _{\frac{1}{2}},\Pi _{\frac{1}{2},\frac{3}{2}},\Delta _{\frac{3}{2},\frac{5}{2}},\Phi _{\frac{5}{2},\frac{7}{2}}$\end{document}Σ12,Π12,32,Δ32,52,Φ52,72), for energies up to 2000 cm−1 above the A(000)2Π3/2 level. The available experimental data have been critically reviewed in the light of the theoretical findings.
Electrical and magnetic properties of Ga1−xGdxN grown by metal organic chemical vapor deposition
Authors: Gupta Shalini , Zaidi Tahir , Melton Andrew , Malguth Enno , Yu Hongbo , Liu Zhiqiang , Liu Xiaotao , Schwartz Justin , Ferguson Ian T.
Published: November 2011

This paper presents the first report on Gd doping (0%–4%) of GaN thin films by metal organic chemical vapor deposition. The Ga1−xGdxN films grown in this study were found to be of good crystalline quality, single-phase, and unstrained, with a high saturation magnetization strength of 20 emu/cm3 being obtained for GaN films doped with 2% Gd at room temperature. Furthermore, these films were found to be conductive with an enhanced n-type behavior suggesting that unintentional donors are responsible for stabilizing the ferromagnetic phase in as-grown Ga1−xGdxN. Additionally, it was found that this magnetization can be enhanced by n-(Si: 1018 cm−3) and p-(Mg: 1019 cm−3) doping to 110 emu/cm3 and ∼500 emu/cm3, respectively. This paper shows empirically that holes are more efficient in stabilizing the ferromagnetic phase as compared to electrons. Overall, this research has resulted in a room temperature ferromagnetic dilute magnetic semiconductor that is conductive and whose magnetic properties can be tuned by carrier doping thus providing a path towards realizing spintronic devices.
Surface roughness scattering model for arbitrarily oriented silicon nanowires
Authors: Tienda-Luna Isabel M. , Ruiz F. G. , Godoy A. , Biel B. , Gámiz F.
Published: November 2011

We present an extension of the unscreened generalized Prange-Nee term used to calculate the surface roughness (SR) limited mobility in arbitrarily oriented square nanowires. The presence of non-diagonal terms in the effective mass tensor is responsible for an additional term not considered in previous studies. We assess the impact of such a modification on the SR limited mobility and on the total mobility (SR and phonon scattering are considered) for devices with different orientation and size. We show that this impact is more relevant for small devices, where the SR plays an important role, even at low inversion charge.
Simultaneous generation of ions and high-order harmonics from thin conjugated polymer foil irradiated with ultrahigh contrast laser
Authors: Choi I. W. , Kim I J. , Pae K. H. , Nam K. H. , Lee C.-L. , Yun H. , Kim H. T. , Lee S. K. , Yu T. J. , Sung J. H. , Pirozhkov A. S. , Ogura K. , Orimo S. , Daido H. , Lee J.
Published: November 2011

We report the manufacturing of an (ultra-)thin foil target made of conjugated polymer, poly(9,9′-dioctylfluorene-co-benzothiadiazole) (F8BT), and the simultaneous observation of laser-accelerated ions and second harmonic radiation, when irradiated with ultrahigh-contrast laser pulse at a maximum intensity of 4 × 1019 W/cm2. Maximum proton energy of 8 MeV is achieved along the target normal direction. Strong second harmonic with over 6% energy ratio compared to fundamental is emitted along the specular direction. Two-dimensional particle-in-cell simulations confirm the simultaneous generation of protons and high-order harmonics, which demonstrates the feasibility of applications requiring particle and radiation sources at once, effectively using the same laser and target.
Oscillation modes of direct current microdischarges with parallel-plate geometry
Authors: Stefanović Ilija , Kuschel Thomas , Škoro Nikola , Marić Dragana , Petrović Zoran Lj , Winter Jörg
Published: November 2011

Two different oscillation modes in microdischarge with parallel-plate geometry have been observed: relaxation oscillations with frequency range between 1.23 and 2.1 kHz and free-running oscillations with 7 kHz frequency. The oscillation modes are induced by increasing power supply voltage or discharge current. For a given power supply voltage, there is a spontaneous transition from one to other oscillation mode and vice versa. Before the transition from relaxation to free-running oscillations, the spontaneous increase of oscillation frequency of relaxation oscillations form 1.3 kHz to 2.1 kHz is measured. Fourier transform spectra of relaxation oscillations reveal chaotic behavior of microdischarges. Volt-ampere (V-A) characteristics associated with relaxation oscillations describes periodical transition between low current, diffuse discharge, and normal glow. However, free-running oscillations appear in subnormal glow only.
Lagrangian time correlations of vorticity alignments in isotropic turbulence: Observations and model predictions
Authors: Chevillard Laurent , Meneveau Charles
Published: November 2011

Motivated by results from recent particle tracking experiments in turbulence Xu et al. [Nature Phys. 7, 709 (2011)], we study the Lagrangian time correlations of vorticity alignments with the three eigenvectors of the deformation-rate tensor. We use data from direct numerical simulations (DNS), and explore the predictions of a Lagrangian model for the velocity gradient tensor. We find that the initial increase of correlation of vorticity direction with the most extensive eigen-direction observed by Xu et al. is reproduced accurately using the Lagrangian model, as well as the evolution of correlation with the other two eigendirections. Conversely, time correlations of vorticity direction with the eigen-frame of the pressure Hessian tensor show differences with the model.
A generalized flux function for three-dimensional magnetic reconnection
Authors: Yeates A. R. , Hornig G.
Published: November 2011

The definition and measurement of magnetic reconnection in three-dimensional magnetic fields with multiple reconnection sites is a challenging problem, particularly in fields lacking null points. We propose a generalization of the familiar two-dimensional concept of a magnetic flux function to the case of a three-dimensional field connecting two planar boundaries. In this initial analysis, we require the normal magnetic field to have the same distribution on both boundaries. Using hyperbolic fixed points of the field line mapping, and their global stable and unstable manifolds, we define a unique flux partition of the magnetic field. This partition is more complicated than the corresponding (well-known) construction in a two-dimensional field, owing to the possibility of heteroclinic points and chaotic magnetic regions. Nevertheless, we show how the partition reconnection rate is readily measured with the generalized flux function. We relate our partition reconnection rate to the common definition of three-dimensional reconnection in terms of integrated parallel electric field. An analytical example demonstrates the theory and shows how the flux partition responds to an isolated reconnection event.
Ion-acoustic solitary waves in ultra-relativistic degenerate pair-ion plasmas
Authors: Rasheed A. , Tsintsadze N. L. , Murtaza G.
Published: November 2011

The arbitrary and the small amplitude ion-acoustic solitary waves (IASWs) have been studied. The former is studied by using the Sagdeev pseudo-potential approach in a plasma consisting of the degenerate ultrarelativistic electrons, positrons, and the non-relativistic classical ions. It is seen that only compressive solitary waves can propagate through such plasmas. The numerical calculations show that the region of existence of the ion-acoustic solitary waves depends upon the positron (ion) number density and the plasma thermal temperature. This study is appropriate for applications in inertial confinement fusion laboratory research as well as the study of astrophysical dense objects such as white dwarf and dense neutron stars.
Role of van der Waals interaction in crystalline ammonia borane
Authors: Yamauchi Kunihiko , Hamada Ikutaro , Huang Hongbin , Oguchi Tamio
Published: November 2011

The structural property of crystalline ammonia borane NH3BH3 is studied by means of density-functional theory calculations. The prototypical inter-molecular N-H⋯H-B dihydrogen bonds are found to be weak so as to make the crystal structure flexible and sensitive to the calculational methods. We found that although conventional generalized gradient approximation describes the intra-molecular bonding in ammonia borane reasonably well, it predicts too large unit cell volume and wrong lattice parameters. Inclusion of the van der Waals forces through the semi-empirical correction improves the cell parameters and inter-molecular geometry significantly, suggesting the important role of van der Waals forces in the bonding between ammonia borane molecules.
Room temperature large-area nanoimprinting for broadband biomimetic antireflection surfaces
Authors: Deniz Hakan , Khudiyev Tural , Buyukserin Fatih , Bayindir Mehmet
Published: November 2011

Ordered arrays of subwavelength hydrogen silsesquioxane (HSQ) nanorods on glass substrates are fabricated using room temperature nanoimprint lithography and anodized aluminum oxide membranes. Moth-eye type nanorod arrays exhibited superior omnidirectional antireflection characteristics in visible wavelengths. The ellipsometric measurements revealed that average specular reflection is remaining below 1% up to 55° incidence angles. Transmission measurements at normal incidence resulted in significant increase in transmitted light intensity with respect to plain glass. Simulations showed that up to 99% transmission could be obtained from double sided tapered HSQ nanorod arrays on HSQ thin film and glass substrates. Achieving large-area, broadband and omnidirectional antireflective surfaces on glass pave the way for applications including photovoltaics.
Magnetic properties of Fe0.4Mn0.6/Co2FeAl bilayers grown on GaAs by molecular-beam epitaxy
Authors: Meng K. K. , Nie S. H. , Yu X. Z. , Wang S. L. , Yan W. S. , Zhao J. H.
Published: November 2011

Polycrystalline Fe0.4Mn0.6 layers with the different thickness are deposited on 4-nm-thick single-crystalline Co2FeAl layers, which are grown on GaAs (001) substrates at room temperature by molecular-beam epitaxy. Both the exchange bias and the in-plane magnetic anisotropies of the bilayers are strongly dependent on the thickness of the Fe0.4Mn0.6 layer. The former is described using a granular level model. A modified Stoner-Wohlfarth model is used to explain the in-plane magnetic anisotropies observed at 5 K, while one possible reason for the magnetic anisotropies measured at 300 K is the complex interfacial magnetic properties proved by x-ray magnetic circular dichroism measurements.
Structure, stability, and mobility of small Pd clusters on the stoichiometric and defective TiO2 (110) surfaces
Authors: Zhang Jin , Alexandrova Anastassia N.
Published: November 2011

We report on the structure and adsorption properties of Pdn (n = 1–4) clusters supported on the rutile TiO2 (110) surfaces with the possible presence of a surface oxygen vacancy or a subsurface Ti-interstitial atom. As predicted by the density functional theory, small Pd clusters prefer to bind to the stoichiometric titania surface or at sites near subsurface Ti-interstitial atoms. The adsorption of Pd clusters changes the electronic structure of the underlying surface. For the surface with an oxygen vacancy, the charge localization and ferromagnetic spin states are found to be largely attenuated owing to the adsorption of Pd clusters. The potential energy surfaces of the Pd monomer on different types of surfaces are also reported. The process of sintering is then simulated via the Metropolis Monte Carlo method. The presence of oxygen vacancy likely leads to the dissociation of Pd clusters. On the stoichiometric surface or surface with Ti-interstitial atom, the Pd monomers tend to sinter into larger clusters, whereas the Pd dimer, trimer, and tetramer appear to be relatively stable below 600 K. This result agrees with the standard sintering model of transition metal clusters and experimental observations.
An off-lattice, self-learning kinetic Monte Carlo method using local environments
Authors: Konwar Dhrubajit , Bhute Vijesh J. , Chatterjee Abhijit
Published: November 2011

We present a method called local environment kinetic Monte Carlo (LE-KMC) method for efficiently performing off-lattice, self-learning kinetic Monte Carlo (KMC) simulations of activated processes in material systems. Like other off-lattice KMC schemes, new atomic processes can be found on-the-fly in LE-KMC. However, a unique feature of LE-KMC is that as long as the assumption that all processes and rates depend only on the local environment is satisfied, LE-KMC provides a general algorithm for (i) unambiguously describing a process in terms of its local atomic environments, (ii) storing new processes and environments in a catalog for later use with standard KMC, and (iii) updating the system based on the local information once a process has been selected for a KMC move. Search, classification, storage and retrieval steps needed while employing local environments and processes in the LE-KMC method are discussed. The advantages and computational cost of LE-KMC are discussed. We assess the performance of the LE-KMC algorithm by considering test systems involving diffusion in a submonolayer Ag and Ag-Cu alloy films on Ag(001) surface.
Effect of C60 layer on the growth mode and conductance of Au and Ag films on Si(111)3-Au and Si(111)3-Ag surfaces
Authors: Tsukanov D. A. , Ryzhkova M. V. , Borisenko E. A. , Bondarenko L. V. , Matetskiy A. V. , Gruznev D. V. , Zotov A. V. , Saranin A. A.
Published: November 2011

The surface morphology and electrical conductance of C60-precoated Si(111)3-Au and Si(111)3-Ag surfaces have been monitored in the course of Au and Ag depositions. In both cases, the deposited metal atoms penetrate through the fullerene layers. However, the similarity in the growth mode does not result in similar dependencies of conductance versus deposited metal dose. Deposition of Au onto the C60-precoated Si(111)3-Au surface leads to a monotonic gradual increase in conductance starting from ∼0.4 ML Au coverage. Deposition of Ag onto the C60-precoated Si(111)3-Ag surface results in a nonmonotone peak-like dependence with a maximum at ∼0.5 ML of Ag. Both dependencies can be explained in terms of the acceptor-type behavior of the fullerenes, which trap the electrons donated by Au or Ag atoms. The difference between the two dependencies is a consequence of the difference in conduction mechanisms at the original surfaces, namely, the main conductance channel in Si(111)3-Au is the space-charge layer, while in Si(111)3-Ag it is the surface state band.
Ion-beam mixing in crystalline and amorphous germanium isotope multilayers
Authors: Bracht H. , Radek M. , Kube R. , Knebel S. , Posselt M. , Schmidt B. , Haller E. E. , Bougeard D.
Published: November 2011

Gallium (Ga) implantation induced self-atom mixing in crystalline and amorphous germanium (Ge) is investigated utilizing isotopically controlled Ge multilayer structures grown by molecular beam epitaxy. The distribution of the Ga ions and the ion-beam induced depth-dependent mixing of the isotope structure was determined by means of secondary ion mass spectrometry. Whereas the distribution of Ga in the crystalline and amorphous Ge is very similar and accurately reproduced by computer simulations based on binary collision approximation (BCA), the ion-beam induced self-atom mixing is found to depend strongly on the state of the Ge structure. The experiments reveal stronger self-atom mixing in crystalline than in amorphous Ge. Atomistic simulations based on BCA reproduce the experimental results only when unphysically low Ge displacement energies are assumed. Analysis of the self-atom mixing induced by silicon implantation confirms the low displacement energy deduced within the BCA approach. This demonstrates that thermal spike mixing contributes significantly to the overall mixing of the Ge isotope structures. The disparity observed in the ion-beam mixing efficiency of crystalline and amorphous Ge indicates different dominant mixing mechanisms. We propose that self-atom mixing in crystalline Ge is mainly controlled by radiation enhanced diffusion during the early stage of mixing before the crystalline structure turns amorphous, whereas in an already amorphous state self-atom mixing is mediated by cooperative diffusion events.
Elimination of surface leakage in gate controlled type-II InAs/GaSb mid-infrared photodetectors
Authors: Chen G. , Nguyen B.-M. , Hoang A. M. , Huang E. K. , Darvish S. R. , Razeghi M.
Published: November 2011

The electrical performance of mid-infrared type-II superlattice M-barrier photodetectors is shown to be limited by surface leakage. By applying gate bias on the mesa sidewall surface, leakage current is significantly reduced. Qualitatively IV modeling shows diffusion-dominated behavior of dark current at temperatures greater than 120 K. At 110 K, the dark current of gated device is reduced by more than 2 orders of magnitude, reaching the measurement system noise floor. With a quantum efficiency of 48% in front side illumination configuration, a 4.7μm cut-off gated device attains a specific detectivity of 2.5 × 1014 cmHz1/2/W at 110 K, which is 3.6 times higher than in ungated devices.
A combination of the tree-code and IPS method to simulate large scale systems by molecular dynamics
Authors: Takahashi Kazuaki Z. , Narumi Tetsu , Yasuoka Kenji
Published: November 2011

An IPS/Tree method which is a combination of the isotropic periodic sum (IPS) method and tree-based method was developed for large-scale molecular dynamics simulations, such as biological and polymer systems, that need hundreds of thousands of molecules. The tree-based method uses a hierarchical tree structure to reduce the calculation cost of long-range interactions. IPS/Tree is an efficient method like IPS/DFFT, which is a combination of the IPS method and FFT in calculating large-scale systems that require massively parallel computers. The IPS method has two different versions: IPSn and IPSp. The basic idea is the same expect for the fact that the IPSn method is applied to calculations for point charges, while the IPSp method is used to calculate polar molecules. The concept of the IPS/Tree method is available for both IPSn and IPSp as IPSn/Tree and IPSp/Tree. Even though the accuracy of the Coulomb forces with tree-based method is well known, the accuracy for the combination of the IPS and tree-based methods is unclear. Therefore, in order to evaluate the accuracy of the IPS/Tree method, we performed molecular dynamics simulations for 32 000 bulk water molecules, which contains around 105 point charges. IPSn/Tree and IPSp/Tree were both applied to study the interaction calculations of Coulombic forces. The accuracy of the Coulombic forces and other physical properties of bulk water systems were evaluated. The IPSp/Tree method not only has reasonably small error in estimating Coulombic forces but the error was almost the same as the theoretical error of the ordinary tree-based method. These facts show that the algorithm of the tree-based method can be successfully applied to the IPSp method. On the other hand, the IPSn/Tree has a relatively large error, which seems to have been derived from the interaction treatment of the original IPSn method. The self-diffusion and radial distribution functions of water were calculated each by both the IPSn/Tree and IPSp/Tree methods, where both methods showed reasonable agreement with the Ewald method. In conclusion, the IPSp/Tree method is a potentially fast and sufficiently accurate technique for predicting transport coefficients and liquid structures of water in a homogeneous system.
Nanoimprinting-induced efficiency enhancement in organic solar cells
Authors: Chou Wei-Yang , Chang Jay , Yen Chia-Te , Tang Fu-Ching , Cheng Horng-Long , Chang Ming-Hua , Lien-Chung Hsu Steve , Chen Jen-Sue , Lee Yung-Chun
Published: November 2011

The performance of bilayer heterojunction, pentacene and perylene tetracarboxylic diimide organic solar cells (OSC) is dramatically enhanced by performing nanoimprinting on the hole transport layer in which poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) nanogratings are built. A standard OSC embeded with PEDOT:PSS gratings enables photocarriers to move toward electrodes. In particular, the visualization of morphologies for these heterojunction layers reveals pillar-like grains that are induced by the geometric effect of PEDOT:PSS gratings. Toghther with analyzing absorption and time-resolved photoluminescence spectra, a consistent correlation between OSC performance, photophysical data, and pillar-like morphology has been obtained for the device with imprinted PEDOT:PSS nanogratings.
Wesley Kingston Whitten 1918 - 2010
Authors: Shelton J. N. , McCullagh P. J.
Published: November 2011

Wesley Kingston Whitten (1918?2010) was recognized as one of Australia's most innovative biological scientists. His studies were the precursor of the science of preimplantation embryology and the technology of assisted reproduction. He pioneered the study of mammalian pheromones and their receptor, the vomeronasal organ. He elucidated the genetic basis of hermaphroditism and mosaicism, and the timing and mechanism of X chromosome inactivation. Several of his recombinant mouse strains continue to provide models for a number of diseases.
Rodney Warren Rickards 1934 - 2007
Authors: Mander Lewis N. , Bennett Martin A.
Published: November 2011

Rod Rickards graduated with first class honours from the University of Sydney in 1955 and began his academic career at the University of Manchester in close association with Arthur Birch. In 1966 he returned to Australia to a foundation appointment in the Research School of Chemistry at the Australian National University, where he spent the remainder of his career. His research was primarily concerned with the organic and biological chemistry of compounds of medical, biological, agricultural and veterinary importance, and was characterized by an integration of organic synthesis, biomimetic synthesis, structural and stereochemical studies, and biosynthetic studies using isotopically labelled precursors in vivo. His interests ranged widely and included antibiotics, regulatory factors that initiate antibiotic production and control cell differentiation and sexuality in microorganisms, elicitors that communicate between bacteria and plants, mammalian hormones of the prostaglandin group that control many aspects of human physiology, juvenile hormones, which mediate the development and reproductive physiology of higher dipteran insects and the therapeutically active components of Cannabis resin.
Alan McLeod Sargeson 1930 - 2008
Authors: Bosnich B.
Published: November 2011

Alan Sargeson was an extraordinarily gifted inorganic chemist who consistently made important and lasting contributions to his discipline. His lifelong interests were in the area of coordination chemistry, especially in the stereochemistry and reactivity of complexes involving the transition element cobalt. Notable discoveries included the elucidation of the mechanisms of substitution reactions of cobalt complexes, and the demonstration that amino acid amides and their esters and phosphate esters incorporated in properly designed metal complexes could achieve the high rates of hydrolysis displayed by enzyme reactions. Perhaps most notable was the discovery of the ready formation of cage complexes where the metal is fully encapsulated. His impact on his field was far-reaching, his achievements were at the highest level and for over thirty years he was among the few who dominated the field.
Riparian vegetation removal alters consumer - resource stoichiometry in an Australian lowland stream
Authors: Giling Darren P. , Reich Paul , Thompson Ross M.
Published: November 2011

Anthropogenic impacts on stream ecosystems generate changes in nutrient and carbon availability which act as stoichiometric challenges to consumers. We tested the hypothesis that removal of Eucalyptus riparian vegetation alters in-stream resource stoichiometry with flow-on effects for a benthic consumer (the freshwater crayfish, Cherax destructor). Sites with high and low riparian canopy cover were selected on a lowland stream in south-eastern Australia. A reduction in riparian vegetation canopy cover was associated with decreased terrestrial detritus (low nutritional quality; high carbon to nitrogen (C : N) ratio) and increased cover of macrophytes and filamentous algae (high quality; low C : N ratio). This resource-quality shift was associated with a small but significant decrease in C. destructor C : N ratio (molar ratio of muscle tissue). This suggests that the animals are deviating from homeostasis and may be in better condition in the stream pools dominated by in-stream productivity. A significant negative relationship between C. destructor length and C : N ratio was observed, suggesting that resource-quality impacts may differ with age. The present study has shown that riparian loss alters stoichiometric interactions in stream benthic ecosystems, with potential consequences for stream processes such as nutrient cycling. Ecological stoichiometric theory should therefore be further utilised to make predictions of ecological impacts in freshwater systems.
The probability of winning break points in Grand Slam men's singles tennis
Authors: Knight Gareth , O'Donoghue Peter
Published: November 2011

The probability of winning games of tennis has been modelled in terms of the probability of the server winning an individual point. These models are based on the assumptions of stationarity of the point and interdependence. Stationarity is the assumption that the outcome of tennis points is not influenced by the game score at the beginning of the point. The purpose of the current investigation was to compare the outcomes of tennis points during break points and non‐break points using data from 528 men's singles tennis matches from all four Grand Slam tournaments in 2008 and 2009. The retrospective probability of the receiver winning a point was 0.42 ± 0.23 during break points which was significantly greater than the 0.38 ± 0.10 during non‐break points (P < 0.001). This, in turn, led to players creating significantly more break points than expected (P < 0.001) and breaking serve more frequently than expected (P < 0.001) for the points won when receiving serve. This is evidence that stationarity cannot be assumed and that models of winning tennis games may need to be enhanced to address improved receiver performance during break points.
Comparison of EMG activity during stable and unstable push‐up protocols
Authors: Anderson Gregory S. , Gaetz Michael , Holzmann Matt , Twist Peter
Published: November 2011

This experiment examined muscle activation measured using electromyography (EMG) during a standardized push‐up performed on stable and unstable surfaces. Fifteen highly trained participants performed four push‐ups: standard (hands and feet on the floor), either the hands or feet on an unstable surface (single instability), and with both hands and feet on unstable surfaces (dual instability). Unstable surfaces were created using a stability ball and an extreme balance board. EMG activity was recorded from three core stabilizers (erector spinae, rectus abdominus and internal obliques), one prime mover (triceps), and one lower body stabilizer (soleus). The EMG time series were smoothed using a 10‐point moving average and root mean squares (RMS) were calculated for the entire time series. The results showed that push‐ups performed with dual instability had significantly greater EMG activation compared to single instability or the stable push‐up. In addition, as instability increased, there was a greater amount of muscle activation for the core stabilizers, prime movers and lower body stabilizers. The findings are consistent with the position that unstable surfaces in conjunction with standard exercises can be used to increase activation of core trunk stabilizers. This may in turn provide increased trunk strength and greater resistance to injury.
A study on backstreaming positive ions on a high power negative ion source for fusion
Authors: Schiesko L. , Hopf C. , Franzen P. , Kraus W. , Riedl R. , Fantz U.
Published: November 2011

Future magnetic-confinement nuclear fusion experiments will be using neutral beam injection (NBI) systems for plasma heating that are based on sources for negative hydrogen ions as opposed to the positive ions mostly used to date. An unavoidable effect in negative NBI (NNBI) systems is the creation of positive ions in the acceleration region due to collisions between the fast negative ions and the neutral background gas. These positive ions are accelerated back into the ion source. At the high extracted ion current densities from NNBI sources and the high acceleration voltages—1 MeV in the case of ITER—the resulting heat load on the backplate of the source and the sputtering rates of the backplate material can be substantial. In this work, sputtering probes and a simple 1D calculation were employed to estimate the flux density of the backstreaming ions in the rear part of the ion source at the long pulse NNBI testbed MANITU (20 kV extraction voltage). It was found that the flux of backstreaming ions is approximately between 0.8 and 2.5% of the flux of negative ions extracted from the source. Experiment and theory are in fair agreement.
Lower hybrid current drive efficiency in tokamaks and wave scattering by density fluctuations at the plasma edge
Authors: Ridolfini V. Pericoli , Apicella M.L. , Calabrò G. , Cianfarani C. , Giovannozzi E. , Panaccione L.
Published: November 2011

The turbulence in the scrape-off layer (SOL) plasma of FTU is characterized in order to assess its effect on the current drive efficiency of the lower hybrid (LH) waves. Amplitude, frequency and perpendicular wave vector of the fluctuations are measured for a variety of the main plasma conditions in front of the LH antenna together with the temperature and density in the SOL and used as inputs for the linear scattering theory of the LH waves developed many years ago. This theoretical model can account for both the frequency spectral broadening of the LH pump and the variations of the driven current, inferred by the perpendicular fast electron bremsstrahlung signals. The fraction of the LH power that is then deduced to be effective for current drive appears to be well related to the calculated optical thickness τ of the SOL. It drops as low as 40% as τ increases, consistent with the model prediction. Possible ways to control the SOL optical depth are investigated and a clear relation of the fluctuation level with the collisionality is found.
Evaluation of Waxy Grain Sorghum for Ethanol Production
Authors: Yan Shuping , Wu Xiaorong , Bean Scott R. , Pedersen Jeffery F. , Tesso Tesfaye , Chen Yuanhong R. , Wang Donghai
Published: November 2011

The objective of this research was to investigate the fermentation performance of waxy grain sorghum for ethanol production. Twenty‐five waxy grain sorghum varieties were evaluated with a laboratory dry‐grind procedure. Total starch and amylose contents were measured following colorimetric procedures. Total starch and amylose contents ranged from 65.4 to 76.3% and from 5.5 to 7.3%, respectively. Fermentation efficiencies were in the range of 86.0–92.2%, corresponding to ethanol yields of 2.61–3.03 gallons/bushel. The advantages of using waxy sorghums for ethanol production include easier gelatinization and low viscosity during liquefaction, higher starch and protein digestibility, higher free amino nitrogen (FAN) content, and shorter fermentation times. The results showed a strong linear relationship between FAN content and fermentation rate. Fermentation rate increased as FAN content increased, especially during the first 30 hr of fermentation (R2 = 0.90). Total starch content in distillers dried grains with solubles (DDGS) was less than 1% for all waxy varieties.
A Comprehensive Analysis of Genes Encoding Small Secreted Proteins Identifies Candidate Effectors in Melampsora larici-populina (Poplar Leaf Rust)
Authors: Hacquard Stéphane , Joly David L. , Lin Yao-Cheng , Tisserant Emilie , Feau Nicolas , Delaruelle Christine , Legué Valérie , Kohler Annegret , Tanguay Philippe , Petre Benjamin , Frey Pascal , Van de Peer Yves , Rouzé Pierre , Martin Francis , Hamelin Richard C. , Duplessis Sébastien
Published: November 2011

The obligate biotrophic rust fungus Melampsora larici-populina is the most devastating and widespread pathogen of poplars. Studies over recent years have identified various small secreted proteins (SSP) from plant biotrophic filamentous pathogens and have highlighted their role as effectors in host–pathogen interactions. The recent analysis of the M. larici-populina genome sequence has revealed the presence of 1,184 SSP-encoding genes in this rust fungus. In the present study, the expression and evolutionary dynamics of these SSP were investigated to pinpoint the arsenal of putative effectors that could be involved in the interaction between the rust fungus and poplar. Similarity with effectors previously described in Melampsora spp., richness in cysteines, and organization in large families were extensively detailed and discussed. Positive selection analyses conducted over clusters of paralogous genes revealed fast-evolving candidate effectors. Transcript profiling of selected M. laricipopulina SSP showed a timely coordinated expression during leaf infection, and the accumulation of four candidate effectors in distinct rust infection structures was demonstrated by immunolocalization. This integrated and multifaceted approach helps to prioritize candidate effector genes for functional studies.
Detection of Phomopsis sclerotioides in Commercial Cucurbit Field Soil by Nested Time-Release PCR
Authors: Ito T. , Fuji S. , Sato E. , Iwadate Y. , Toda T. , Furuya H.
Published: November 2011

A polymerase chain reaction (PCR)-based molecular method to detect Phomopsis sclerotioides in soil was developed using a species-specific primer pair. To improve sensitivity of the detection, three PCR techniques were used; namely, nested PCR using the primer pair internal transcribed spacer (ITS)1 and ITS4, time-release PCR using two different DNA polymerases (recombinant Taq and AmpliTaq Gold), and fluorescent PCR to obtain fluorescent-labeled PCR products that can be analyzed by capillary electrophoresis. The latter two techniques were combined and termed nested time-release fluorescent (NTRF)-PCR. The minimum concentration of DNA required to obtain species-specific PCR products successfully was 50 fg/μg. Using the NTRF-PCR method, the fungus could be detected in sandy soil that was artificially infested at a density of 10 CFU/g. The pathogen was detected in most soil samples collected from commercial cucumber fields in which visual disease symptoms had appeared, and even in samples collected from fields where visual disease symptoms had not appeared. To prevent the invasion and establishment of root-inhabiting pathogens such as P. sclerotioides, it is critical to detect the fungus in soil as soon as possible after its introduction into a cucumber-growing region.
Anthracnose and Gummy Stem Blight Are Reduced on Watermelon Grown on a No-Till Hairy Vetch Cover Crop
Authors: Zhou X. G. , Everts K. L.
Published: November 2011

Multiple applications of fungicides are used to manage anthracnose caused by Colletotrichum orbiculare and gummy stem blight caused by Didymella bryoniae, the two most common and destructive diseases on watermelon (Citrullus lanatus) in the mid-Atlantic region of the United States. To develop a sustainable, nonchemical management option, a split-plot experiment was conducted over 3 years to evaluate the effects of a no-till hairy vetch (Vicia villosa) cover crop on disease severity, plant growth, and fruit yield compared with two conventional bedding systems and fungicide application. The main plots were bedding strategies consisting of bare ground, polyethylene covering, or a hairy vetch cover crop that was planted in the fall, killed the following spring, and left on the soil surface as an organic mulch. The subplots were a nonfungicide control or a weekly application of a standard fungicide program. Hairy vetch mulch provided greater than a 65% reduction in the area under the disease progress curves of anthracnose and gummy stem blight and greater than an 88% decrease in diseased fruit compared with bare ground or polyethylene mulch. The reductions were comparable with those achieved by fungicide applications. Watermelon vine lengths in plots with hairy vetch were similar to or greater than those in plots with polyethylene or bare ground that were treated with fungicides. Marketable fruit in plots with hairy vetch was higher compared with bare ground in 2 of 3 years and was similar to that in plots treated with fungicides in all 3 years. Addition of fungicide application to hairy vetch treatment further reduced anthracnose in 1 year and gummy stem blight in 2 years but did not significantly increase fruit yield in all 3 years. This is the first demonstration that a no-till hairy vetch production system can reduce anthracnose and gummy stem blight on watermelon and that the production system has the potential to mitigate damage caused by these diseases.
First Report of Stem Bleeding in Coconut Caused by Ceratocystis paradoxa in Hainan, China
Authors: Yu F.-Y. , Niu X.-Q. , Tang Q.-H. , Zhu H. , Song W.-W. , Qin W.-Q. , Lin C.-H.
Published: November 2011

Stem bleeding of coconut was discovered in 2009 in Hainan, China. Affected trunk areas exhibited dark discoloration and a reddish brown or rust-colored liquid bleeding from different points. Stem tissues under the lesions rotted and became brownish yellow to black. Affected plants died within 3 to 4 months after stem symptoms first appeared. Stem bleeding of coconut is known to occur in production areas worldwide. The disease was first reported in Sri Lanka (1), caused severe damage to PB-121 hybrids in Indonesia (2), and is now known to occur in many other coconut-producing countries. However, to our knowledge, this is the first report of the disease in China. A fungus was isolated from lesion margins of diseased coconut trees. Colonies on potato dextrose agar (PDA) were white, became black 1 to 2 days later, and emitted a strong, fruity aroma. The fungus produced conidia, which were cylindrical, colorless to pale brown, and 6.9 to 14.9 × 3.1 to 6.0 μm, and oval, black chlamydospores that were 7.9 to 19.4 × 4.6 to 11.0 μm. The optimum temperature for mycelial growth ranged from 25 to 35°C and it did not grow at temperatures lower than 5°C or higher than 40°C. On the basis of these characteristics, the fungus was identified as Ceratocystis paradoxa (Dade) C. Moreau (anamorph Thielaviopsis paradoxa (de Seynes) Höhn). The internal transcribed spacer (ITS) region was amplified from genomic DNA with primers ITS1 and ITS4 and the PCR products were sequenced (GenBank Accession No. JQ039332). BLAST analysis showed 99% sequence similarity with C. paradoxa (GenBank Accession No. HQ248205.1). Pathogenicity of the fungus was tested by inoculating 10, 3-year-old coconut trees of the cv. green tall at the 12-leaf stage in the field. Agar plugs (5 mm in diameter) from the periphery of 7-day-old C. paradoxa colonies grown on PDA were placed on healthy trunks, rachis, and leaves, which were either wounded or unwounded. Wounds were made with a sterilized cork borer. Sites of the inoculations were wrapped with plastic tape to prevent desiccation; the experiment was repeated three times. Controls received plain PDA discs. Two weeks after inoculation, characteristic rusty brown lesions appeared only on wounded plants that were inoculated with the fungus. A brownish liquid oozed from the points of inoculation. Controls did not show signs of disease development. C. paradoxa was reisolated from the diseased tissues. Infection occurred on wounded sites only, suggesting that wounds may be required for infection. To prevent stem bleeding of coconut trees by C. paradoxa, vigilant cultural practices must be maintained to avoid causing wounds on the trees.

References: (1) S. A. Alfieri. Plant Pathol. Circular No. 53. Florida Department of Agriculture Division of Plant Industry, 1967. (2) D. R. N. Warwick and E. E. M. Passos. Trop. Plant Pathol. 34:175, 2009.
Effect of oxidized low-density lipoprotein concentration polarization on human smooth muscle cells' proliferation, cycle, apoptosis and oxidized low-density lipoprotein uptake
Authors: Ding Zufeng , Liu Shijie , Yang Bo , Fan Yubo , Deng Xiaoyan
Published: November 2011

To clarify the effect of concentration polarization of oxidative modification of low-density lipoproteins (ox-LDLs) on human smooth muscle cells (SMCs), the proliferation, ox-LDL uptake and apoptosis with SMCs cultured on permeable (the permeable group) or non-permeable membranes (the non-permeable group) were analysed by 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay, spectrofluorometry and flow cytometry using a parallel-plate flow chamber technique. The concentration polarization of ox-LDLs at the surface of the cultured cell monolayer was assessed by confocal laser microscopy. The results showed that concentration polarization of ox-LDLs could indeed occur at the cultured cell monolayer surface of the permeable group, leading to an enhanced wall concentration of ox-LDLs that was over 15 per cent higher than the bulk concentration of the perfusion solution at a pressure of 100 mmHg. When concentration of ox-LDLs in the perfusion solution was less than or equal to 100 µg ml
–1
, SMCs' proliferation was induced, while cell apoptosis was induced when its concentration was above 150 µg ml
–1
. The uptake of ox-LDLs by the cultured cells was significantly higher for the permeable group than for the non-permeable group. In addition, the ox-LDL-induced cell death and apoptosis were much more severe in the permeable group than that in the non-permeable group. Therefore, the experimental study suggests that concentration polarization of ox-LDLs plays an adverse role in the vascular system owing to its toxicity to vascular cells, in turn enhance ox-LDL infiltration into the arterial wall and accelerate SMC apoptosis.