bluuebunny/crossref_metadata_2025 huggingface dataset:
THE FIDUCIARY CONSTITUTION OF HUMAN RIGHTS
Authors: Fox-Decent Evan , Criddle Evan J.
Published: March 2010

We argue that human rights are best conceived as norms arising from a fiduciary relationship that exists between states (or statelike actors) and the citizens and noncitizens subject to their power. These norms draw on a Kantian conception of moral personhood, protecting agents from instrumentalization and domination. They do not, however, exist in the abstract as timeless natural rights. Instead, they are correlates of the state's fiduciary duty to provide equal security under the rule of law, a duty that flows from the state's institutional assumption of irresistible sovereign powers.
Is Hurricane Activity in One Basin Tied to Another?
Authors: Wang Chunzai , Lee Sang‐Ki
Published: March 2010

Each year, tropical cyclones and hurricanes leave millions homeless worldwide and account for, on average, over $100 billion of damage in the United States alone [Schmidt et al., 2009]. In 2005, a record‐ breaking 15 hurricanes formed in the North Atlantic, four of which reached category 5 strength. Over the course of that season, more than 3000 hurricane‐related deaths occurred and fiscal damage reached $157 billion.

Because a better understanding of when and where tropical cyclones and hurricanes will form and strike will help societies better prepare for adverse effects, improving the understanding of these storms is very important. In the Western Hemisphere, tropical cyclones can form and develop in both the tropical North Atlantic and eastern North Pacific oceans, which are separated by the landmass of Central America. From the point of view of large‐scale atmospheric circulation and its influence on tropical cyclones [e.g.,Bell and Chelliah, 2006], it is not surprising that tropical cyclone variabilities in these two basins are related, because of their geographic proximity. But several questions remain: How they are related? What physical mechanisms drive this relation?
Open government
Authors: Showstack Randy
Published: March 2010

U.S. President Barack Obama's Memorandum on Transparency and Open Government requires federal agencies to take steps toward increased transparency, public participation, and collaboration.
Kenneth C. Spengler (1915–2010)
Authors: Bierly Eugene
Published: March 2010

Kenneth C. Spengler, executive director emeritus of the American Meteorological Society (AMS), died 28 January at the age of 94. He was a retired life member of AGU who joined in 1946.

Ken was born in Harrisburg, Pa., and attended Dickinson College, where he majored in mathematics and physics. In 1940 he was sent to the Massachusetts Institute of Technology as a second lieutenant in the U.S. Army Reserves for a 1‐year graduate course in meteorology. The University of Nevada granted Ken an honorary doctorate in 1966. During World War II, Ken was stationed at the Army Air Corps Weather Research Center at Bolling Airfield in Washington, D.C. The research center was later moved to Weather Bureau headquarters in Washington and eventually to the Pentagon, where Ken made contact with many well‐known meteorologists.
Binding Pattern Determination Of Class of Antifungal Drugs
Authors: Tandon Arpit , Naqvi A , Chitranshi Nitin , Sinha Siddharth
Published: March 2010

Crystal Structure of cytochrome p450 2B4 has 476 amino acids, through docking approach we have attempted to explain the specificity of CYP2B4, total 28 imidazole drug were used for the studies as antifungal drugs in which bound bifonazole (reference) shows the binding energy of -8.67 kcal/mol .Compound Miconazole shows the minimum binding energy of -10.45 kcal/mol. The 2B4-bifonazole structure identified 10 residues (ALA 298, GLY 299, GLU 301, THR 302, ILE 363, VAL 292) within 6.5 Å of the active site of bifonazole. GLU 301, THR 302 are also located in 6.5 Å of the bound ligand in 2B4 structure. Due to the presence of the multiple binding substrates in cytochrome p450, it acts as the major target of many drugs in xenobiotic metabolism.
Thiol isomerases negatively regulate the cellular shedding activity of ADAM17
Authors: Willems Sofie H. , Tape Christopher J. , Stanley Peter L. , Taylor Neil A. , Mills Ian G. , Neal David E. , McCafferty John , Murphy Gillian
Published: March 2010

ADAM17 (where ADAM is ‘a disintegrin and metalloproteinase’) can rapidly modulate cell-surface signalling events by the proteolytic release of soluble forms of proligands for cellular receptors. Many regulatory pathways affect the ADAM17 sheddase activity, but the mechanisms for the activation are still not clear. We have utilized a cell-based ADAM17 assay to show that thiol isomerases, specifically PDI (protein disulfide isomerase), could be responsible for maintaining ADAM17 in an inactive form. Down-regulation of thiol isomerases, by changes in the redox environment (for instance as elicited by phorbol ester modulation of mitochondrial reactive oxygen species) markedly enhanced ADAM17 activation. On the basis of ELISA binding studies with novel fragment antibodies against ADAM17 we propose that isomerization of the disulfide bonds in ADAM17, and the subsequent conformational changes, form the basis for the modulation of ADAM17 activity. The shuffling of disulfide bond patterns in ADAMs has been suggested by a number of recent adamalysin crystal structures, with distinct disulfide bond patterns altering the relative orientations of the domains. Such a mechanism is rapid and reversible, and the role of thiol isomerases should be investigated further as a potential factor in the redox regulation of ADAM17.
Lipid remodelling of glycosylphosphatidylinositol (GPI) glycoconjugates in procyclic-form trypanosomes: biosynthesis and processing of GPIs revisited
Authors: Bütikofer Peter , Greganova Eva , Liu Yuk-Chien , Edwards Ian J. , Lehane Michael J. , Acosta-Serrano Alvaro
Published: March 2010

The African trypanosome, Trypanosoma brucei, has been used as a model to study the biosynthesis of GPI (glycosylphosphatidylinositol) anchors. In mammalian (bloodstream)-form parasites, diacyl-type GPI precursors are remodelled in their lipid moieties before attachment to variant surface glycoproteins. In contrast, the GPI precursors of insect (procyclic)-form parasites, consisting of lyso-(acyl)PI (inositol-acylated acyl-lyso-phosphatidylinositol) species, remain unaltered before protein attachment. By using a combination of metabolic labelling, cell-free assays and complementary MS analyses, we show in the present study that GPI-anchored glycoconjugates in T. congolense procyclic forms initially receive tri-acylated GPI precursors, which are subsequently de-acylated either at the glycerol backbone or on the inositol ring. Chemical and enzymatic treatments of [3H]myristate-labelled lipids in combination with ESI-MS/MS (electrospray ionization-tandem MS) and MALDI-QIT-TOF-MS3 (matrix-assisted laser-desorption ionization–quadrupole ion trap–time-of-flight MS) analyses indicate that the structure of the lipid moieties of steady-state GPI lipids from T. congolense procyclic forms consist of a mixture of lyso-(acyl)PI, diacyl-PI and diacyl-(acyl)PI species. Interestingly, some of these species are myristoylated at the sn-2 position. To our knowledge, this is the first demonstration of lipid remodelling at the level of protein- or polysaccharide-linked GPI anchors in procyclic-form trypanosomes.
Effects of different detachment procedures on viability, nitroxide reduction kinetics and plasma membrane heterogeneity of V‐79 cells
Authors: Batista Urška , Garvas Maja , Nemec Marjana , Schara Milan , Veranič Peter , Koklic Tilen
Published: March 2010

Cell detachment procedures can cause severe damage to cells. Many studies require cells to be detached before measurements; therefore, research on cells that have been grown attached to the bottom of the culture dish and later detached represents a special problem with respect to the experimental results when the properties of cell membranes undergo small changes such as in spectroscopic studies of membrane permeability. We characterized the influence of three different detachment procedures: cell scraping by rubber policeman, trypsinization and a citrate buffer treatment on V‐79 cells in the plateau phase of growth (arrested in G1). We have measured cell viability by a dye‐exclusion test; nitroxide reduction kinetics and membrane fluidity by EPR (electron paramagnetic resonance) method using the lipophilic spin‐probe MeFASL(10,3) (5‐doxylpalmitoyl‐methylester), which partitions mainly in cell membranes and the hydrophilic spin‐probe TEMPONE (4‐oxo‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl). The resulting cell damage due to the detachment process was observed with SEM (scanning electron microscopy). We found out that cell viability was 91% for trypsin treatment, 85% for citrate treatment and 70% for cell scraping. Though the plasma membrane was mechanically damaged by scraping, the membrane domain structure was not significantly altered compared with other detachment methods. On the other hand, the spin‐probe reduction rate, which depends both on the transport across plasma membrane as well as on metabolic properties of cells, was the highest for trypsin method, suggesting that metabolic rate was the least influenced. Only the reduction rate of trypsin‐treated cells stayed unchanged after 4 h of stirring in suspension. These results suggest that, compared with scraping cells or using citrate buffer, the most suitable detachment method for V‐79 cells is detachment by trypsin and keeping cells in the stirred cell suspension until measurement. This method provides the highest cell viability, less visible damage on SEM micrographs and leaves the metabolic rate of cells unchanged.
Efficient magnetic hysteresis model for field and stress application in magnetostrictive Galfenol
Authors: Evans P. G. , Dapino M. J.
Published: March 2010

We present a discrete energy-averaged model for the nonlinear and hysteretic relation of magnetization and strain to magnetic field and stress. Analytic expressions from energy minimization describe three-dimensional rotations of domains about easy crystal directions in regions where domain rotation is the dominant process and provide a means for direct calculation of magnetic anisotropy constants. The anhysteretic material behavior due to the combined effect of domain rotation and domain wall motion is described with an energy weighted average while the hysteretic material behavior is described with an evolution equation for the domain volume fractions. As a result of using a finite set of locally defined energy expressions rather than a single globally defined expression, the model is 100 times faster than previous energy weighting models and is accurate for materials with any magnetocrystalline anisotropy. The model is used to interpret magnetization and strain measurements of ⟨100⟩ oriented Fe79.1Ga20.9 and Fe81.5Ga18.5 as well as ⟨110⟩ oriented Fe81.6Ga18.4.
Bilayer metal gate electrodes with tunable work function: Mechanism and proposed model
Authors: Lu Ching-Huang , Wong Gloria M. T. , Birringer Ryan , Dauskardt Reinhold , Deal Michael D. , Clemens Bruce M. , Nishi Yoshio
Published: March 2010

A bilayer metal structure has been demonstrated to adjust the gate work function over the Si band gap. The underlying tuning mechanism is believed to be due to metal interdiffusion based on comparison of work function behavior under different anneal conditions. In this paper, we conduct physical characterization on bilayer metal gates and successfully verify that the interdiffusion is the cause of the work function tuning. Furthermore, we find that metal interdiffusion significantly slows down after an initial anneal, resulting in a stable work function. A diffusion model involving the annealing out of fast diffusion paths is proposed to explain the work function results.
Pitch gradient induced by disklike chiral molecular diffusion in chiral-nematic liquid crystals
Authors: Cui Xiaopeng , Huang Qi , Liu Tao , Cao Hui , Liu Qing , Yang Zhou , Yang Huai
Published: March 2010

Disklike molecules were introduced as chiral dopants to induce a pitch gradient in the polymer stabilized cholesteric liquid crystals films. A sandwich-cell was fabricated with two different substrates, one of which was coated by the disklike molecule layer and another by a parallel-aligned pattern of polyvinyl alcohol. The pitch gradient was formed by molecular diffusion across the film thickness and further stabilized by photo-initiated crosslinking of the polymerizable monomers during the diffusion process. The effect of the deposition amount of the disklike chiral molecules on the diffusion rate and the consequent pitch gradient was studied.
Thermoelectric properties of electrically stressed Sb/Bi–Sb–Te multilayered films
Authors: Liao Chien-Neng , Chang Chih-Yu , Chu Hsu-Shen
Published: March 2010

Electrically stressed Bi–Sb–Te thin films have demonstrated markedly enhanced Hall mobility and moderately reduced carrier concentration. To lower electrical resistivity further, a Sb-inserted Bi–Sb–Te multilayer structure was prepared through consecutively sputtering Bi–Sb–Te and Sb layers followed by electric current stressing. The electrically stressed Sb/Bi–Sb–Te film demonstrates high carrier concentration and enhanced Hall mobility. We propose that the additional Sb supply suppresses electromigration-induced Sb depletion in crystal lattices, thus maintains high carrier concentration of the Bi–Sb–Te film. The presented approach provides a simple means to optimize thermoelectric properties of Bi–Sb–Te films.
Low temperature silicon dioxide by thermal atomic layer deposition: Investigation of material properties
Authors: Hiller D. , Zierold R. , Bachmann J. , Alexe M. , Yang Y. , Gerlach J. W. , Stesmans A. , Jivanescu M. , Müller U. , Vogt J. , Hilmer H. , Löper P. , Künle M. , Munnik F. , Nielsch K. , Zacharias M.
Published: March 2010

SiO 2 is the most widely used dielectric material but its growth or deposition involves high thermal budgets or suffers from shadowing effects. The low-temperature method presented here (150 °C) for the preparation of SiO2 by thermal atomic layer deposition (ALD) provides perfect uniformity and surface coverage even into nanoscale pores, which may well suit recent demands in nanoelectronics and nanotechnology. The ALD reaction based on 3-aminopropyltriethoxysilane, water, and ozone provides outstanding SiO2 quality and is free of catalysts or corrosive by-products. A variety of optical, structural, and electrical properties are investigated by means of infrared spectroscopy, UV-Vis spectroscopy, secondary ion mass spectrometry, capacitance-voltage and current-voltage measurements, electron spin resonance, Rutherford backscattering, elastic recoil detection analysis, atomic force microscopy, and variable angle spectroscopic ellipsometry. Many features, such as the optical constants (n, k) and optical transmission and surface roughness (1.5 Å), are found to be similar to thermal oxide quality. Rapid thermal annealing (RTA) at 1000 °C is demonstrated to significantly improve certain properties, in particular by reducing the etch rate in hydrofluoric acid, oxide charges, and interface defects. Besides a small amount of OH groups and a few atomic per mille of nitrogen in the oxide remaining from the growth and curable by RTA no impurities could be traced. Altogether, the data point to a first reliable low temperature ALD-growth process for silicon dioxide.
Metal/III-V Schottky barrier height tuning for the design of nonalloyed III-V field-effect transistor source/drain contacts
Authors: Hu Jenny , Saraswat Krishna C. , Wong H.-S. Philip
Published: March 2010

In this work, we introduce a novel nonalloyed contact structure for n-GaAs and n-In0.53Ga0.47As by using single metals in combination with a thin dielectric to tune the effective metal/III-V work function toward the conduction band edge. We reduced the effective Schottky barrier height (ΦB,eff) of Al/GaAs from 0.75 to 0.17 eV through the use of a thin atomic layer deposition Al2O3. Barrier height reduction was verified for a variety of metals (Y, Er, Al, Ti, and W) through direct measurements and deduced from increased diode current and reduced contact resistance. Similar results were observed on n-In0.53Ga0.47As. Two possible underlying mechanisms are discussed: one based on the formation of a dielectric dipole and the other based on the blocking of metal induced gap states. This structure has applications as a nonalloyed low resistance ohmic contact for III-V metal-oxide-semiconductor field-effect transistors (MOSFETs) or high electron mobility transistors (HEMTs), and as a near zero barrier height contact for III-V Schottky barrier field-effect transistors or diodes.
A model-based approach to compensate for the dynamics convolution effect on nanomechanical property measurement
Authors: Xu Zhonghua , Zou Qingze
Published: March 2010

A model-based approach to compensate for the dynamics convolution effect on the measurement of nanomechanical properties is proposed. In indentation-based approach to measure nanomechanical properties of soft materials, an excitation force consisting of multiple frequencies needs to be accurately exerted (from the probe) to the sample material, and the indentation generated in the sample needs to be accurately measured. However, when the measurement frequency range becomes close to the bandwidth of the instrument hardware, the instrument dynamics along with the probe-sample interaction can be convoluted with the mechanical behavior of the soft material, resulting in distortions in both the applied force and the measured indentation, which, in turn, directly lead to errors in the measured nanomechanical properties of the material (e.g., the creep compliance). In this article, the dynamics involved in indentation-based nanomechanical property measurement is investigated to reveal that the convoluted dynamics effect can be described as the difference between the lightly damped probe-sample interaction and the overdamped nanomechanical behavior of the soft sample. Thus, these two different dynamics effects can be decoupled via numerical fitting based on the viscoelastic model of the soft material. The proposed approach is illustrated by implementing it to compensate for the dynamics convolution effect on a broadband viscoelasticity measurement of a polydimethylsiloxane sample using a scanning probe microscope.
Study of sensitivity and noise in the piezoelectric self-sensing and self-actuating cantilever with an integrated Wheatstone bridge circuit
Authors: Shin ChaeHo , Jeon InSu , Khim Zheong G. , Hong J. W. , Nam HyoJin
Published: March 2010

A detection method using a self-sensing cantilever is more desirable than other detection methods (optical fiber and laser beam bounce detection) that are bulky and require alignment. The advantage of the self-sensing cantilever is its simplicity, particularly its simple structure. It can be used for the construction of an atomic force microscopy system with a vacuum, fluids, and a low temperature chamber. Additionally, the self-actuating cantilever can be used for a high speed scanning system because the bandwidth is larger than the bulk scanner. Frequently, ZnO film has been used as an actuator in a self-actuating cantilever. In this paper, we studied the characteristics of the self-sensing and self-actuating cantilever with an integrated Wheatstone bridge circuit substituting the ZnO film with a lead zirconate titanate (PZT) film as the actuator. We can reduce the leakage current (to less than 10−4 A/cm2) in the PZT cantilever and improve sensor sensitivity through a reduction of noise level from the external sensor circuit using the Wheatstone bridge circuit embedded into the cantilever. The self-sensing and actuating cantilever with an integrated Wheatstone bridge circuit was compared with a commercial self-sensing cantilever or self-sensing and actuating cantilever without an integrated Wheatstone bridge circuit. The measurement results have shown that sensing the signal to noise level and the minimum detectable deflection improved to 4.78 mV and 1.18 nm, respectively. We believe that this cantilever allows for easier system integration and miniaturization, provides better controllability and higher scan speeds, and offers the potential for full automation.
Influence of rare-earth addition on dielectric properties and relaxor behavior of barium zirconium titanate thin films
Authors: Gao Lina , Zhai Jiwei , Zhang Yewen , Yao Xi
Published: March 2010

Ba ( 1 – 3 / 2 x ) M x Zr 0.20 Ti 0.80 O 3 (M=La, Ce, and Dy; x=0, 0.005, 0.01, 0.02, and 0.05) thin films are successfully deposited on Pt(111)/Ti/SiO2/Si(100) substrates by the sol-gel method, and the influence of the rare-earth ions content on the microstructure, dielectric properties, and phase transformation behavior is investigated in detail. As a result, the rare-earth ions with various ionic radii enter the perovskite lattice to substitute for A-site Ba2+ ions and inhibit the grain growth. With the increase in rare-earth ions concentration, the dielectric constant, dielectric loss, tunability, and leakage current density of Ba(1–3/2x)MxZr0.20Ti0.80O3 thin films decreased. Simultaneously the temperature of maximum of dielectric constant shifts to the lower temperature and relaxor phase transition behavior is observed due to the rare-earth ions substitution. And the degree of the relaxor behavior is enhanced with the increase in rare-earth ions content and ionic radius.
Double-diffusive Marangoni convection in a rectangular cavity: Onset of convection
Authors: Chen Zhi-Wu , Li Yok-sheung , Zhan Jie-Min
Published: March 2010

Double-diffusive Marangoni convection in a rectangular cavity with horizontal temperature and concentration gradients is considered. Attention is restricted to the case where the opposing thermal and solutal Marangoni effects are of equal magnitude (solutal to thermal Marangoni number ratio Rσ=−1). In this case a no-flow equilibrium solution exists and can remain stable up to a critical thermal Marangoni number. Linear stability analysis and direct numerical simulation show that this critical value corresponds to a supercritical Hopf bifurcation point, which leads the quiescent fluid directly into the oscillatory flow regime. Influences of the Lewis number Le, Prandtl number Pr, and the cavity aspect ratio A (height/length) on the onset of instability are systematically investigated and different modes of oscillation are obtained. The first mode is first destabilized and then stabilized. Sometimes it never gets onset. A physical illustration is provided to demonstrate the instability mechanism and to explain why the oscillatory flow after the onset of instability corresponds to countersense rotating vortices traveling from right to left in the present configuration, as obtained by direct numerical simulation. Finally the simultaneous existence of both steady and oscillatory flow regimes is shown. While the oscillatory flow arises from small disturbances, the steady flow, which has been described in the literature, is induced by finite amplitude disturbances.
Scaling of the plasma sheath in a magnetic field parallel to the wall
Authors: Krasheninnikova Natalia S. , Tang Xianzhu , Roytershteyn Vadim S.
Published: March 2010

Motivated by the magnetized target fusion [R. E. Siemon et al., Comments Plasma Phys. Controlled Fusion 18, 363 (1999)] experiment, a systematic investigation of the scaling of a one-dimensional plasma sheath with a magnetic field parallel to the wall was carried out using analytical theory and the particle-in-cell code VPIC [K. J. Bowers et al., Phys. Plasmas 15, 055703 (2008)]. Starting with a uniform Maxwellian distribution in three-dimensional velocity space, plasma consisting of collisionless electrons, and ions of the same temperature interacts with a perfectly absorbing wall. A much larger ion Larmor radius causes the wall to be charged positively, creating an electric field that tends to repel the ions and attract the electrons, which is the opposite of the conventional Bohm sheath [D. Bohm, Characteristics of Electrical Discharges in Magnetic Fields (McGraw-Hill, New York, 1949)]. This manifests in the form of gyro-orbit modification by this spatially varying electric field, the degree of which is found to intricately depend on the relation between three parameters: electron and ion thermal Larmor radii and plasma Debye length: ρthe, ρthi, and λD. Furthermore, the study of the sheath width scaling through the analysis of the full width at half max of electric field, xEh, elucidates three distinct types of behavior of xEh, corresponding to three different regimes: ρthi<λD, ρthe<λD<ρthi, and λD<ρthe. In addition to the sheath width, the scaling of the wall potential ϕWall, as well as the role of the ion mass and charge Z are investigated. The results of this analytical and computational approach can also be useful in studying the plasma sheath in the conventional magnetic confinement devices, in particular at the first wall of tokamaks.
Communications: Hamiltonian regulated cell signaling network
Authors: Wang Ge , Zaman Muhammad H.
Published: March 2010

Cell signaling is fundamental to cell survival and disease progression. Traditional approaches to study these networks have focused largely on probabilistic approaches, with a large number of ad hoc assumptions. In this paper, we develop a linear Hamiltonian model to study the integrin signaling network. The integrin signaling network is central to cell adhesion, migration, and differentiation, but has not been studied in the same detail as other cell cycle networks. In this study, the integrin signaling network with 16 nodes in thermal fluctuations is analyzed through ensemble averages on the linear Hamiltonian model. This new and analytically rigorous approach offers a quick method to find out the dominant nodes in the complex network, which operate in the thermal noise regime. The robust on/off transitions due to the different initial inputs also reflect the inherent structure in the network, providing new insights into structure and function of the network.
Light-induced superlow electric field for domain reversal in near-stoichiometric magnesium-doped lithium niobate
Authors: Zeng Hao , Kong Yongfa , Liu Hongde , Chen Shaolin , Huang Ziheng , Ge Xinyu , Xu Jingjun
Published: March 2010

Light-induced domain reversal of near-stoichiometric Mg-doped LiNbO3 crystal was investigated with a focused 532 nm continuous laser beam. The lowest electric field applied to accomplish domain nucleation is only 30 V/mm and 1/80 of the coercive field, which is safe and convenient for us to fabricate domain structures. Under this superlow applied field, the pinning effect of domain wall is so obvious that the inverted domain reveals a gear shape contrary to the hexagon in a higher applied field. Then two-dimensional domain patterns with the smallest domain size of 4 μm have been fabricated.
In situ peeling of one-dimensional nanostructures using a dual-probe nanotweezer
Authors: Xie Hui , Régnier Stéphane
Published: March 2010

We reported a method for in situ peeling force measurement of one-dimensional nanostructures using a dual-probe nanotweezer, which is developed on the principle of force microscopy. Benefiting from capabilities of image scanning and accurate force sensing, the nanotweezer is capable of positioning one-dimensional nanostructures deposited on a surface and then performing in situ peeling tests with pick-and-place operations at different peeling locations of interest along a selected nanostructure. In experiments, nanoscale peeling of silicon nanowires (SiNWs) on a silicon substrate has been studied. Peeling locations at the end and in the middle of the SiNW were tested and the results indicate that approximate peeling energies are needed.
Measuring temperature-dependent activation energy in thermally activated processes: A 2D Arrhenius plot method
Authors: Li Jian V. , Johnston Steven W. , Yan Yanfa , Levi Dean H.
Published: March 2010

Thermally activated processes are characterized by two key quantities, activation energy (Ea) and pre-exponential factor (ν0), which may be temperature dependent. The accurate measurement of Ea, ν0, and their temperature dependence is critical for understanding the thermal activation mechanisms of non-Arrhenius processes. However, the classic 1D Arrhenius plot-based methods cannot unambiguously measure Ea, ν0, and their temperature dependence due to the mathematical impossibility of resolving two unknown 1D arrays from one 1D experimental data array. Here, we propose a 2D Arrhenius plot method to solve this fundamental problem. Our approach measures Ea at any temperature from matching the first and second moments of the data calculated with respect to temperature and rate in the 2D temperature-rate plane, and therefore is able to unambiguously solve Ea, ν0, and their temperature dependence. The case study of deep level emission in a Cu(In,Ga)Se2 solar cell using the 2D Arrhenius plot method reveals clear temperature dependent behavior of Ea and ν0, which has not been observable by its 1D predecessors.
Transmission of gigawatt-level microwave using a beam-rotating mode converter in a relativistic backward wave oscillator
Authors: Jung H. C. , Min S. H. , Park G. S. , An J. , Lee S. H. , Yoon Y. J. , Kim J. Y. , Choi J. H. , So J. H. , Petelin M.
Published: March 2010

Gigawatt-level circularly polarized radiation was transmitted using a coaxial beam rotating antenna in an X-band relativistic backward wave oscillator. The mode conversion from the TM01 mode to the circularly polarized TE11-like mode was experimentally and numerically shown. The simulated radiation pattern was in good agreement with the measured radiation pattern.
Relaxation dynamics of the metal-semiconductor transition in VO2 thin films
Authors: Claassen J. H. , Lu J. W. , West K. G. , Wolf S. A.
Published: March 2010

The temperature dependent metal-insulator transition in VO2 films displays substantial hysteresis. This is usually attributed to supercooling or superheating in the grains. In the hysteretic region at fixed temperature there is a relaxation of the resistance toward a presumed equilibrium value. We have made careful measurements of this relaxation, and find that it proceeds with a logarithmic dependence on time. If the transformation is thermally activated in individual grains, the log(t) behavior can be explained either by a wide distribution of activation energies U among grains or a dependence of U on the phase of adjacent grains.
A grazing incidence x-ray streak camera for ultrafast, single-shot measurements
Authors: Feng J. , Engelhorn K. , Cho B. I. , Lee H. J. , Greaves M. , Weber C. P. , Falcone R. W. , Padmore H. A. , Heimann P. A.
Published: March 2010

An ultrafast x-ray streak camera has been realized using a grazing incidence reflection photocathode. X-rays are incident on a gold photocathode at a grazing angle of 20° and photoemitted electrons are focused by a large aperture magnetic solenoid lens. The streak camera has high quantum efficiency, 600 fs temporal resolution, and 6 mm imaging length in the spectral direction. Its single shot capability eliminates temporal smearing due to sweep jitter, and allows recording of the ultrafast dynamics of samples that undergo nonreversible changes.
Fiber coupled waveguide grating structures
Authors: Feng Shengfei , Zhang Xinping , Wang Hao , Xin Mudi , Lu Zhenzhen
Published: March 2010

Fabrication and characterization of the miniature device of waveguide grating-structures (WGS) on the end facet of an optical fiber are demonstrated. A layer of ZnO between the fiber and the grating structures serves as the waveguide. The fiber is used to direct the excitation light to the WGS and to carry the signal response back to the detection system. The narrow-band waveguide resonance mode tunable in the visible spectrum can be measured through the fiber in both the transmission and reflection. This nanodevice may be suitable as long-range sensors for the detection of refractive-index changes in nontransparent or toxic liquids.
Single-defect photonic crystal cavity laser fabricated by a combination of laser holography and focused ion beam lithography
Authors: Ahn Sungmo , Kim Sihan , Jeon Heonsu
Published: March 2010

Large-scale, high-throughput fabrication of photonic crystal (PC)-based devices was achieved by using a combination of laser holography (for background PC generation) and focused ion beam lithography (for defect formation). An array of InP-based square-lattice PC lasers with a single air-hole defect was fabricated by this combined lithography. The resultant lasers consistently exhibited two lasing modes, which were identified as quadrupole and dipole modes on the basis of their spectral and polarization properties. The high cavity Q-factor (∼2200) and low laser threshold (∼0.25 mW) indicated that the laser quality was comparable to that of the PC lasers formed by electron-beam lithography.
Hydrogen in plasma-nanofabrication: Selective control of nanostructure heating and passivation
Authors: Wolter Matthias , Levchenko Igor , Kersten Holger , Ostrikov Kostya (Ken)
Published: March 2010

The possibility of independent control of the surface fluxes of energy and hydrogen-containing radicals, thus enabling selective control of the nanostructure heating and passivation, is demonstrated. In situ energy flux measurements reveal that even a small addition of H2 to low-pressure Ar plasmas leads to a dramatic increase in the energy deposition through H recombination on the surface. The heat release is quenched by a sequential addition of a hydrocarbon precursor while the surface passivation remains effective. Such selective control offers an effective mechanism for deterministic control of the growth shape, crystallinity, and density of nanostructures in plasma-aided nanofabrication.
Acousto-optically tunable lithium niobate photonic crystal
Authors: Courjal Nadège , Benchabane Sarah , Dahdah Jean , Ulliac Gwenn , Gruson Yannick , Laude Vincent
Published: March 2010

We report on an active two-dimensional lithium niobate photonic crystal (PhC) driven by stationary Rayleigh surface acoustic waves. The configuration relies on two interdigital transducers that modulate the refractive index through the acousto-optical effect. Highly efficient, compact acousto-optical PhCs with an active length of only 13 μm and a driving electrical power of 20 mW have been fabricated and characterized. Experiments show that an enhancement factor of the elasto-optical interaction of the order of 61 is obtained thanks to slow light effects in the PhC.
In situ seed development and in vitro regeneration of three difficult-to-propagate Lepidosperma species (Cyperaceae)
Authors: Kodym Andrea , Turner Shane , Delpratt John
Published: March 2010

Field studies of fruit production from Lepidosperma concavum R.Br., L. laterale R.Br. and L. longitudinale Labill. showed that large proportions (21–77%) of fruits were unfilled and that filled and unfilled fruits looked alike. Bagging of inflorescences demonstrated that filled fruits tended to be shed, while empty fruits remained within the inflorescence. Time of collection was critical for obtaining viable seeds, with successful harvesting limited to a short period (weeks) after maturation. The timing of flowering and fruit maturation were fairly consistent between species, populations and years in our study area. In L. concavum fruit production was increased in cultivation compared with wild populations. In all three species, very little or no germination of fruits occurred under nursery conditions. In vitro culture initiation was attempted using intact fruits, nicked fruits and seeds on 1/2MS (Murashige and Skoog) medium with 1 µM zeatin and 0.5 µM gibberellic acid in darkness. Culture of intact fruit resulted in no germination, while nicked fruit showed some germination response. Best results were achieved from seeds with germination occurring as early as 7 to 18 days depending on the species. Germination of L. concavum, L. laterale and L. longitudinale was 86%, 64% and 83% respectively within 5 weeks. Germination response was strongly influenced by seed maturity. Mature seeds germinated significantly faster than immature seeds. On a small proportion of cultured seeds, calli formed and differentiated into numerous plantlets on growth regulator-free medium. Given the promising results observed in this study, in vitro culture appears to be a practical means of mass propagating Lepidosperma species.
Mycorrhizal specificity of Diuris fragrantissima (Orchidaceae) and persistence in a reintroduced population
Authors: Smith Zoë F. , James Elizabeth A. , McLean Cassandra B.
Published: March 2010

This study investigated the diversity and specificity of mycorrhizal fungi associated with five Diuris (Orchidaceae) taxa in south-eastern Australia, as part of a reintroduction program for the endangered species Diuris fragrantissima. We compared fungi isolated from D. fragrantissima occurring naturally in the only remaining population with those from artificially cultivated plants and reintroduced plants 18 months after planting in a new field site west of Melbourne. Genetic similarity of nuclear internal transcribed spacer and nuclear large subunit DNA sequences showed that Diuris taxa associate with a narrow taxonomic range of fungi within the cosmopolitan family Tulasnellaceae in the Rhizoctonia alliance. All fungal isolates induced host seed germination and hence were considered mycorrhizal. Fungal isolates from naturally occurring D. fragrantissima plants showed a higher level of genetic similarity than fungi isolated from cultivated plants. This observation suggests that, historically, the species may have associated with a more genetically variable range of Tulasnella fungi. Artificially cultivated D. fragrantissima were propagated aseptically from seed and spontaneously formed mycorrhizal associations within 6 months of transfer to potting media. Wild collected D. fragrantissima plants maintained in cultivation for over 30 years were found to contain mycorrhizal fungi similar to those isolated from naturally occurring plants in 2004–2006. Mycorrhizal associations in artificially cultivated D. fragrantissima were present in 18 randomly sampled plants 18 months after reintroduction. Further, associations formed between several reintroduced plants and a fungus concurrently inoculated into site soil. We propose that future orchid reintroductions may benefit from the concurrent addition of suitable mycorrhizal fungi to site soil. Maintenance of orchid mycorrhizal relationships after reintroduction is essential to improve long-term viability of reintroduced populations.
The effect of water level on lateral movements of fish between river and off-channel habitats and implications for management
Authors: Lyon Jarod , Stuart Ivor , Ramsey David , O'Mahony Justin
Published: March 2010

Off-channel habitats, such as wetlands and backwaters, are important for the productivity of river systems and for many species of native fish. This study aimed to investigate the fish community, timing and cues that stimulated movement to and from off-channel habitats in the highly regulated Lake Hume to Lake Mulwala reach of the Murray River, south-eastern Australia. In 2004–05, 193 712 fish were collected moving bi-directionally between a 50-km section of the Murray River and several off-channel habitats. Lateral fish movements approximated water level fluctuations. Generally as water levels rose, fish left the main river channel and moved into newly flooded off-channel habitats; there was bi-directional movement as water levels peaked; on falling levels fish moved back to the permanent riverine habitats. Fish previously classified as ‘wetland specialists’, such as carp gudgeons (Hypseleotris spp.), have a more flexible movement and life-history strategy including riverine habitation. The high degree of lateral movement indicates the importance of habitat connectivity for the small-bodied fish community. Wetlands adjacent to the Murray River are becoming increasingly regulated by small weirs and ensuring lateral fish movement will be important in maintaining riverine-wetland biodiversity.
Stable isotopes reveal post-release trophodynamic and ontogenetic changes in a released finfish, mulloway (Argyrosomus japonicus)
Authors: Taylor Matthew D. , Mazumder Debashish
Published: March 2010

Carbon and nitrogen stable isotope ratios were analysed for hatchery-reared, recaptured and wild mulloway, Argyrosomus japonicus, to investigate temporal and growth-related changes in isotopic composition for stocked fish after release, and to evaluate changes in isotopic composition in terms of ontogenetic dietary switches. δ13C and δ15N values decreased and increased, respectively, after release. The isotope composition of released fish was distinct from wild fish until 200 days after release, but after 200 days post-release fish did not differ significantly from wild fish of similar or greater sizes. Abrupt dietary transitions from crustaceans to teleost fish (>50 cm total length (TL)) were evident in a rapid δ13C and δ15N change in wild mulloway, and δ15N was significantly greater in wild fish >65 cm TL compared with wild fish <50 cm TL. Multivariate carbon and nitrogen isotopic data were suitable for separating stocked and wild fish for up to 200 days after release, but did not separate wild fish grouped according to dietary composition. Carbon and nitrogen isotopic composition closely reflected dietary transitions and rapid adaptation by stocked mulloway to wild diets, which was evident in a high tissue turnover rate of up to 0.017 day–1. Stable isotopes are a useful tool for examining the integration of released fish into stocked ecosystems and can be used to describe convergence in the diets of wild and released fish.
Coastal upwelling may overwhelm the effect of sewage discharges in rocky intertidal communities of the Peruvian coast
Authors: Firstater Fausto N. , Hidalgo Fernando J. , Lomovasky Betina J. , Tarazona Juan , Flores Georgina , Iribarne Oscar O.
Published: March 2010

In coastal productive environments, such as upwelling systems, sewage effluents might represent an important input of nutrients affecting intertidal community development and structure. Using descriptive and experimental approaches, the community spatial variation and early succession in relation to a point-source effluent discharge in a rocky intertidal of an upwelling affected area (Ancón Bay, Peru) was analysed. The relative contribution of herbivory to the observed patterns was also analysed. Dissolved nutrient concentrations, macroalgal isotopic signatures and N content revealed a significant input of nutrients at the outfall, although this contribution was not reflected in the algal assemblage, but in higher abundances of mytilids, ophiuroids and limpets. Cover of most sessile organisms (biofilm, Ulva spp., mytilids and barnacles) varied among sites throughout early succession, and grazers only enhanced the cover of the red algae Gelidium spp. Differences in succession patterns could not be attributed to discharge effects. The results of this study suggest that the community development is bottom-up controlled in the entire bay, which is likely to be due to the upwelling that operates at larger temporal and spatial scales. If so, nutrient input derived from coastal upwelling may sometimes overwhelm the role of anthropogenic nutrient loadings in shaping intertidal communities.
Dynamic stability in dry season food webs within tropical floodplain rivers
Authors: Leigh Catherine , Burford Michele A. , Sheldon Fran , Bunn Stuart E.
Published: March 2010

Debate exists about the effects of hydrological variation on food web dynamics and the relative importance of different sources of organic carbon fuelling food webs in floodplain rivers. Stable carbon isotope analyses and ecological stoichiometry were used to determine the basal sources in dry season macroinvertebrate food webs in two floodplain river systems of Australia’s wet–dry tropics that have contrasting flow regimes. Algae, associated with phytoplankton and biofilm, were the primary food source, potentially contributing >55% organic carbon to the biomass of a wide range of primary and secondary consumers. However, many consumers assimilated other sources in addition to algae, e.g. detritus from local C3 riparian vegetation. Food webs were characterised by substantial flexibility in the number and types of sources identified as important, which was indicative of generalist feeding strategies. These findings suggest ‘dynamic stability’ in the food webs, which imparts resilience against natural disturbances like flow regime seasonality and variation in hydrological connectivity. This adaptation may be characteristic of macroinvertebrate assemblages in highly seasonal river systems or in those with high levels of flow variability.
Is cotton-strip tensile strength a surrogate for microbial activity in groundwater?
Authors: Lategan M. J. , Korbel K. , Hose G. C.
Published: March 2010

The cotton strip assay uses the loss of tensile strength of cotton strips as a measure of microbial cellulolytic activity. Its suitability for measuring general microbial activity in groundwater was tested by examining the relationship of tensile strength, abundance of cellulolytic organisms and general microbial activity on cotton strips deployed in bores. The hypothesis was that the strength of cotton strips would decline with increasing abundance and activity of cellulolytic organisms, and as cellulolysis makes resources available to other microbial groups, cotton strength loss should also be related to increased overall microbial activity. The correlation between the abundance of cellulolytic organisms and cotton strength was not significant. Two main factors influenced this relationship: (i) effectiveness of the media in detecting cellulolytic moulds and (ii) inter-community interactions. After accounting for the presence of moulds through partial correlation, the relationship between tensile strength and abundance of cellulolytic organisms was stronger and significant. Both cotton strength and abundance of cellulolytic organisms correlated significantly with general microbial activity. These results support the use of the cotton strip assay, and cotton tensile strength as a surrogate for microbial activity in groundwater.