bluuebunny/crossref_metadata_2025 huggingface dataset:
Static critical behavior of the 3D frustrated Heisenberg model on a layered triangular lattice
Authors: Murtazaev A. K. , Kamilov J. K. , Ramazanov M. K.
Published: March 2006

The critical properties of the 3D frustrated Heisenberg model on a layered triangular lattice are investigated by the Monte Carlo method. The theory of finite-size scaling is used to calculate the magnetic and chiral critical exponents of the specific heat (α), susceptibility (γ,γk), magnetization (β,βk), and correlation length (ν,νk). It is shown that the 3D frustrated Heisenberg model on a layered triangular lattice forms a new universality class of critical behavior.
Ultrasonic attenuation in a chain crystal containing resonantly scattering defects
Authors: Chulkin E. P.
Published: March 2006

The frequency dependence and low-temperature behavior of the ultrasonic attenuation coefficient of the lattice of a chain crystal containing resonantly scattering defects. The influence of delay and weak localization effects for an acoustic vibrational mode with a large flat part of its dispersion relation. The resonance-level parameters for which the processes of localization are manifested weakly in comparison with the delay effect are determined. The question of the possible manifestation of these effects in experiments on the ultrasonic absorption in the quasi-one-dimensional crystals (Ta1−xNbxSe4)2I is discussed.
Mobility of a particle immersed in a liquid film between two fluids
Authors: Felderhof B. U.
Published: March 2006

The mobility of a particle immersed in a liquid film between two viscous fluids is calculated in point approximation. The mobility in the direction parallel to the film diverges logarithmically as the ratio of the sum of outside viscosities to the film viscosity tends to zero, as in the [Saffman-Delbrück, Proc. Natl. Acad. Sci. U.S.A. 72, 3111 (1975)] expression for the mobility of a particle embedded in a membrane. A simple expression for the limiting behavior is derived. For any values of the parameters the mobility tensor can be evaluated by numerical quadrature of two one-dimensional integrals.
Assessing a new nonempirical density functional: Difficulties in treating π-conjugation effects
Authors: Sancho-García J. C.
Published: March 2006

The reliability of the Tao-Perdew-Staroverov-Scuseria (TPSS) exchange-correlation functional for the description of conjugation effects in model π-conjugated systems has been thoroughly assessed through the calculation of torsion energy profiles. The functional reproduces qualitatively the shape of torsional potentials but, interestingly, the mixing of TPSS and exact exchange governs the quantitative results: thus, well-defined hybrid extensions of the functional are consistently employed to improve the results. The hybrid approaches led to more accurate descriptions of conjugation effects but, however, the finest performance along the whole range of dihedral angles was obtained by a customized mixing of pure or hybrid TPSS functionals and wave function methods in a multicoefficient fashion. Despite the successful construction of this nonempirical functional, higher rungs of the ladder of methods in which TPSS is based are hoped to reduce the errors with respect to reference data for π-conjugated systems.
A novel mesophase formed by top-shaped molecules in the bulk and unsupported thin films: A molecular dynamics study
Authors: Kim Hojin , Bedrov Dmitry , Smith Grant D. , Magda Jules J.
Published: March 2006

We have used molecular dynamics simulations to investigate the ordering of top-shaped molecules in bulk phases and in unsupported thin films. Each rigid anisotropic molecule was composed of 11 Lennard-Jones interaction centers (beads). In an attempt to enhance the nematic stability in preference to smectic, the three central beads were assigned a larger Lennard-Jones diameter than the tail beads, giving the molecule a shape resembling a top. The molecular model was found to exhibit an unusual bulk mesophase with long-range orientational order and with molecular center-of-mass positions arranged in parallel interdigitated layers, with layer spacing smaller than half the length of the long axis of a molecule. However, despite the toplike molecular shape, no nematic phase was observed in the pressure range studied. Unsupported films of the isotropic liquid were cooled in order to locate a triple point between the novel mesophase, vapor, and isotropic liquid. At temperatures slightly above the triple point, enhanced surface ordering of molecules was found to occur in the unsupported film. At temperatures slightly below the triple point, the preferred molecular alignment in the unsupported film was parallel to the interface, in violation of arguments that have been proposed based on the relative enthalpies of various cleavage planes for close-packed structures.
Opposed-anvil-type high-pressure and high-temperature apparatus using sintered diamond
Authors: Gotou Hirotada , Yagi Takehiko , Frost Daniel J. , Rubie David C.
Published: March 2006

An opposed-anvil-type high-pressure and high-temperature apparatus is developed, adopting sintered diamond as the anvil material. Pressures and temperatures up to about 30GPa and 1700K can be achieved routinely without difficulty. The use of a metal gasket dramatically reduces the occurrence of blowouts and results in very stable pressure generation. By improving the preparation methods and materials used for the small components of the sample assembly, experiments can be performed much more easily than with previous versions of the apparatus. Pressures and temperatures were measured by in situ x-ray diffraction using two different pressure markers. Temperatures of the sample were also estimated from the resistance change of the heater. Estimated pressure and temperature conditions were checked by the phase transformation of Al-bearing MgSiO3 and were consistent with the stability field of the perovskite phase as previously reported. Compared to the laser-heated diamond anvil cell, this apparatus has the advantage of uniform temperature and a much larger sample volume. As a result, the new apparatus has major advantages for studying multicomponent systems and the partitioning of the elements.
Digital lock-in technique for the motional Stark effect diagnostic
Authors: Shi Yuejiang
Published: March 2006

The fast data acquisition system (FAS) has been developed for the motional Stark effect (MSE) diagnostic in many machines. The FAS digitizes the signals coming directly out of the photomultiplier tube. The software solution of digital lock-in technique to derive the MSE signals from the data of FAS is presented in this article. The calculated frequency and phase of the photoelastic modulators (PEMs) with this digital lock-in technique can reach so high precision that the first, second, and fourth harmonic frequency signals of PEMs can be perfectly recovered.
Automated sample preparation station for studying self-diffusion in porous solids with NMR spectroscopy
Authors: Hedin Niklas , DeMartin Gregory J. , Reyes Sebastián C.
Published: March 2006

In studies of gas diffusion in porous solids with nuclear magnetic resonance (NMR) spectroscopy the sample preparation procedure becomes very important. An apparatus is presented here that pretreats the sample ex situ and accurately sets the desired pressure and temperature within the NMR tube prior to its introduction in the spectrometer. The gas manifold that supplies the NMR tube is also connected to a microbalance containing another portion of the same sample, which is kept at the same temperature as the sample in the NMR tube. This arrangement permits the simultaneous measurement of the adsorption loading on the sample, which is required for the interpretation of the NMR diffusion experiments. Furthermore, to ensure a good seal of the NMR tube, a hybrid valve design composed of titanium, a Teflon® seat, and Kalrez® O-rings is utilized. A computer controlled algorithm ensures the accuracy and reproducibility of all the procedures, enabling the NMR diffusion experiments to be performed at well controlled conditions of pressure, temperature, and amount of gas adsorbed on the porous sample.
Power-law scaling for macroscopic entropy and microscopic complexity: Evidence from human movement and posture
Authors: Hong S. Lee , Bodfish James W. , Newell Karl M.
Published: March 2006

We investigated the relationship between macroscopic entropy and microscopic complexity of the dynamics of body rocking and sitting still across adults with stereotyped movement disorder and mental retardation (profound and severe) against controls matched for age, height, and weight. This analysis was performed through the examination of center of pressure (COP) motion on the mediolateral (side-to-side) and anteroposterior (fore-aft) dimensions and the entropy of the relative phase between the two dimensions of motion. Intentional body rocking and stereotypical body rocking possessed similar slopes for their respective frequency spectra, but differences were revealed during maintenance of sitting postures. The dynamics of sitting in the control group produced lower spectral slopes and higher complexity (approximate entropy). In the controls, the higher complexity found on each dimension of motion was related to a weaker coupling between dimensions. Information entropy of the relative phase between the two dimensions of COP motion and irregularity (complexity) of their respective motions fitted a power-law function, revealing a relationship between macroscopic entropy and microscopic complexity across both groups and behaviors. This power-law relation affords the postulation that the organization of movement and posture dynamics occurs as a fractal process.
Toward uniform nanotubular compounds: Synthetic approach and ab initio calculations
Authors: Miller Glen P. , Okano Shinya , Tománek David
Published: March 2006

We propose to synthesize a new class of single-walled nanotubular compounds (SWNCs) and investigate the interplay between their structural and electronic properties using ab initio density functional calculations. SWNCs are composed of cyclacenes of variable diameter interconnected by various linker compounds. Cyclacenes map directly onto and can be viewed as the shortest segments of (n,0) zigzag carbon nanotubes. We focus on cyclacenes with n=6–12 fused benzene rings interconnected by biphenyl, tetrazine, or acetylene linkers. Depending upon the nature and the orientation of the linkers, we find it possible to change the systems from narrow-gap to wide-gap semiconductors, and to modulate the band dispersion, suggesting the possibility of band gap engineering.
Defocusing microscopy: An approach for red blood cell optics
Authors: Mesquita Leonardo G. , Agero Ubirajara , Mesquita Oscar N.
Published: March 2006

Thin transparent objects (phase objects) can become visible in a bright-field light microscope, if the microscope is slightly defocused. Thick transparent objects, like red blood cells (RBC), are seen because some of their parts are always out of focus. By applying our recently developed defocusing microscopy technique to RBC, we are able to interpret RBC bright-field light microscopy images, an old standing problem. From the average image contrast we obtain RBC shape, size, and refractive index. From contrast fluctuations caused by the flicker phenomenon, we obtain RBC bending modulus and cytoplasm viscosity.
Spectroscopic strain measurement methodology: Degree-of-polarization photoluminescence versus photocurrent spectroscopy
Authors: Tomm Jens W. , Tien Tran Quoc , Cassidy Daniel T.
Published: March 2006

A methodological approach to strain analysis in semiconductor devices is presented. Two methods, degree-of-polarization of photoluminescence and photocurrent spectroscopy, are compared by analyzing a spatially inhomogeneous strained test sample, namely, a high-power diode laser array that is affected by packaging-induced stress. Both methods concordantly reveal a −0.1% uniaxial compression in the vicinity of the midpoint of the active region of the device, demonstrating the compatibility of and justifying the assumptions involved in the two different approaches. Furthermore, we discuss some distinctive details of the processing-induced strains observed in the vicinities of metallized contacts and grooves involved in the device design.
Enhancement and patterning of ultraviolet emission in ZnO with an electron beam
Authors: Xie Rongguo , Sekiguchi Takashi , Ishigaki Takamasa , Ohashi Naoki , Li Dongsheng , Yang Deren , Liu Baodan , Bando Yoshio
Published: March 2006

An intense enhancement of ultraviolet (UV) emission was observed in various kinds of ZnO samples that were prepared using a wet chemical method when they were under electron-beam irradiation. The UV emission can increase to more than two times its initial value, whereas the visible emission reduces to a negligible value. We suggest that this enhancement effect mainly results from electron-stimulated desorption of adsorbed water. Applying this effect, we have developed a simple technique of directly writing submicrometer UV emission patterns in ZnO with an electron beam without changing the material’s surface morphology.
Controllable gas-liquid phase flow patterns and monodisperse microbubbles in a microfluidic T-junction device
Authors: Xu J. H. , Li S. W. , Wang Y. J. , Luo G. S.
Published: March 2006

This letter describes the gas-liquid phase flow patterns and the mechanism of generation of monodisperse microbubbles in a T-junction microfluidic device using the crossflowing shear-rupturing technique. The bubble size is ranged from 100 to 500μm. The air phase states as isolate air slugs, “pearl necklaces,” periodic isolate bubbles, zig-zag bubble patterns, and multiple-bubble layer can be observed in the wider measured channel. The bubble size relates with the continuous phase flow velocity and viscosity as Vb∝1∕(μcuc), while being almost independent of surface tension γ and air phase flow rate Qg, for the conditions used in this work. The bubble formation mechanism by using the crossflowing shear-rupturing technique is different from the hydrodynamic flow focusing and both geometry-dominated breakup techniques. Our system provides independent control of both the size and volume fraction of dispersed bubbles.
Directed movement of Au–Si droplets towards buried dislocation networks on silicon bicrystals
Authors: Liu C. H. , Wu W. W. , Chen L. J.
Published: March 2006

Directed movement of Au–Si alloy droplets towards buried dislocation grids on a Si bicrystal has been observed by in situ ultrahigh vacuum transmission electron microscopy. It was found that once the underlying dislocation structure was dissolved, the movement of Au–Si droplets was directed to the region with remaining dislocation network. The migration of Au–Si droplets is driven by the energy difference between the strained bicrystal and nonstrained single-crystal silicon. The directed movement by the buried dislocation network is potentially significant in a wide range of technologies.
Gate electrode processes in an electrolyte-gated transistor: Non-Faradaically versus Faradaically coupled conductivity modulation of a polyacetylene ionomer
Authors: Lin Fuding , Lonergan Mark C.
Published: March 2006

The significance of gate electrode processes to the transfer characteristics of electrochemical transistors is demonstrated using a device based on a polyacetylene ionomer. Two regimes of operation are identified. The first involves a conventional redox process where two Faradaic processes balance: oxidative doping of the polymer to modulate conductivity is coupled to reduction at the gate electrode. The second involves a nonconventional hybrid mode of operation: doping is coupled to the charging of an ionic double layer at the gate electrode, which is a non-Faradaic process. The implications of these two regimes on the design and performance of electrochemical transistors are discussed.
Spatially resolved and temperature dependent thermal tuning rates of high-power diode laser arrays
Authors: Kreissl Michael , Tien Tran Quoc , Tomm Jens W. , Lorenzen D. , Kozlowska Anna , Latoszek Mateusz , Oudart Myriam , Nagle Julien
Published: March 2006

Thermal tuning properties of passively cooled 808nm emitting high-power diode laser bars are analyzed. Data from standard devices packaged on Cu heat sinks and identical devices mounted on expansion-matched Cu–W heat sinks are compared. For a standard device, we find up to one-fifth of the thermal tuning rate of −(0.56±0.04)meVK−1 to be caused by pressure tuning driven by the relaxation of compressive packaging-induced stress for increasing temperatures. For devices packaged on expansion-matched heat sinks the observed tuning rate of −(0.46±0.01)meVK−1 represents almost the genuine thermal tuning rate of the semiconductor device structure. Thus this technology potentially leads to improved device properties.
Simple fabrication of a ZnO nanowire photodetector with a fast photoresponse time
Authors: Law J. B. K. , Thong J. T. L.
Published: March 2006

A zinc oxide (ZnO) nanowire photodetector was fabricated by a simple method of growing ZnO nanowires bridging the gap of two patterned zinc electrodes. The nanowire growth is self-catalytic, involving the direct heating of patterned Zn electrodes at 700°C in an O2∕Ar gas flow of 20SCCM (standard cubic centimeter per minute at STP)/80SCCM, respectively, at atmospheric pressure for 3h. The fabricated photodetector demonstrated fast response of shorter than 0.4ms to UV illumination in air, which could be attributed to the adsorption, desorption, and diffusion of water molecules in the air onto the nanowire significantly influencing the photoresponse.
Fabrication of integrated nanogap electrodes by surface-catalyzed chemical deposition
Authors: Ah Chil Seong , Yun Yong Ju , Lee Joon Sung , Park Hyung Ju , Ha Dong Han , Yun Wan Soo
Published: March 2006

Integrated nanogap electrodes with separations of several nanometers were fabricated by a simple and highly reproducible method of surface-catalyzed chemical deposition. By this method, multifingered nanogap electrodes of a few nanometers in separation were fabricated with a good yield (over 90%). The fabrication was achieved by immersing the initial gap electrodes obtained by conventional e-beam lithography into a stock solution containing Au ions and a mild reducing agent. After the surface-catalyzed chemical deposition, a rather wide initial gap distance of 18–52nm was decreased to a few nanometers, showing a much narrower distribution (centered at 3.3nm).
Silicon doped boron carbide nanorod growth via a solid-liquid-solid process
Authors: Han Wei-Qiang
Published: March 2006

Here we report the synthesis of silicon doped boron carbide (Si-doped B4C) nanorods via a solid reaction using activated carbon, boron, and silicon powder as reactants. These nanorods have been studied by high-resolution transmission electron microscopy, scanning electron microscopy, electron energy loss spectroscopy, and energy-dispersive x-ray spectrometry. The diameter of Si-doped B4C nanorods ranges from 15to70nm. The length of Si-doped B4C nanorods is up to 30μm. NixCoyBz nanoparticles are used as catalysts for the growth of Si-doped B4C nanorods. A solid-liquid-solid growth mechanism is proposed.
Data Storage, Processing, and Visualization for the Australia Telescope Compact Array
Authors: Murphy Tara , Lamb Peter , Owen Christopher , Marquarding Malte
Published: March 2006

We present three Virtual Observatory tools developed at the Australia Telescope National Facility (ATNF) for the storage, processing and visualization of Australia Telescope Compact Array (ATCA) data. These are the Australia Telescope Online Archive, a prototype data-reduction pipeline, and the Remote Visualization System. These tools were developed in the context of the Virtual Observatory and were intended to be both useful for astronomers and technology demonstrators. We discuss the design and implementation of these tools, as well as issues that should be considered when developing similar systems for future telescopes.
The Near-Infrared Surface Brightness Distribution of NGC 4696
Authors: Mur Pablo Arnalte , Ellis Simon C. , Colless Matthew
Published: March 2006

We present H-band observations of the elliptical galaxy NGC 4696, the brightest member of the Centaurus cluster of galaxies. We have measured its light profile, using a two-dimensional fitting algorithm, out to a radius of 180 arcsec (37 h70−1 kpc). The profile is well described by a de Vaucouleurs law, with an effective radius of 35.3 ± 1.0 h70−1 kpc. There is no need for the extra free parameter allowed by a Sérsic law. Allowing for a variation of 0.3% in the sky level, the profile obtained is compatible with data from the Two-Micron All Sky Survey (2MASS). The profile shows no sign of either a truncation or an extended halo.
Saturn's Icy Moon Rhea: A Prediction for its Bulk Chemical Composition and Physical Structure at the Time of the Cassini Spacecraft First Flyby
Authors: Prentice Andrew J. R.
Published: March 2006

I report a model for the formation of Saturn's family of mid-sized icy moons to coincide with the first flypast of Rhea by the Cassini spacecraft on 2005 November 26. It is proposed that the moons had condensed from a concentric family of orbiting gas rings that were shed some 4.6 × 109 yr ago by the proto-Saturnian (hereafter p-Sat) cloud. The p-Sat cloud is made up of gas and residual grains of the gas ring that was shed by the proto-Solar cloud (hereafter PSC) at Saturn's orbit. The bulk of the condensate within this proto-Solar ring accumulates to form Saturn's central core of mass ∼10–20 M⊕ (M⊕ = Earth mass). The process of formation of Saturn's solid core thus provides an opportunity for the p-Sat cloud to become depleted in rock and water ice relative to the usual solar abundances of these materials. Nitrogen, which exists as uncondensing N2 in the PSC and as NH3 in the p-Sat cloud, retains its solar abundance relative to H2. If the depletion factor of solids relative to gas is ζdep = 0.25, as suggested by the low mass of Rhea relative to solar abundance expectations, the mass-percent ratio of NH3 to H2O in the dense p-Sat cloud is 36:64. Numerical and structural models for Rhea are constructed on the basis of a ‘cosmogonic’ bulk chemical composition of hydrated rock (mass fraction 0.385), H2O ice (0.395), and NH3 ice (0.220). It is difficult to construct a chemically differentiated model of Rhea whose mean density matches the observed value ρRhea = 1.23 ± 0.02 g cm−3 for reasonable bounds of the controlling parameters. Chemically homogeneous models can, however, be constrained to match the observed Rhea density provided that the mass fraction of NH3 is permitted to exceed the cosmogonic value by a factor ζNH3 = 1.20–1.35. A large proportion of NH3 in the ice mass inhibits the formation of the dense crystalline phase II of H2O ice at high pressure. This may explain the lack of compressional features on the surface of the satellite that are expected as a result of ice II formation in the cooling core. The favoured model of Rhea is chemically uniform and has mass proportions of rock (0.369), H2O ice (0.378), and NH3 ice (0.253). The enhancement factor of NH3 lies within the measured uncertainties of the solar abundance of nitrogen. The satellite is very cold and nearly isodense. The predicted axial moment-of-inertia coefficient is [C/MR2]Rhea = 0.399 ± 0.004.
The Group Evolution Multiwavelength Study (GEMS): The Sample and Datasets
Authors: Forbes Duncan A. , Ponman Trevor , Pearce Frazer , Osmond John , Kilborn Virginia , Brough Sarah , Raychaudhury Somak , Mundell Carole , Miles Trevor , Kern Katie
Published: March 2006

Galaxy groups have been under-studied relative to their richer counterparts — clusters. The Group Evolution Multiwavelength Study (GEMS) aims to redress some of the balance. Here we describe the GEMS sample selection and resulting sample of 60 nearby (< 130 Mpc) galaxy groups and our multiwavelength dataset of X-ray, optical, and Hı imaging. ROSAT X-ray images of each group are presented. GEMS also utilizes near-infrared imaging from the 2MASS survey and optical spectra from the 6dFGS. These observational data are complemented by mock group catalogues generated from the latest ΓCDM simulations with gas physics included. Existing GEMS publications are briefly highlighted as are future publication plans.
Impacts of feeding system and season on milk composition and Cheddar cheese yield in a subtropical environment
Authors: Amenu B. , Cowan T. , Deeth H. , Moss R.
Published: March 2006

Milk obtained from cows on 2 subtropical dairy feeding systems were compared for their suitability for Cheddar cheese manufacture. Cheeses were made in a small-scale cheesemaking plant capable of making 2 blocks (about 2 kg each) of Cheddar cheese concurrently. Its repeatability was tested over 10 separate cheesemaking days with no significant differences being found between the 2 vats in cheesemaking parameters or cheese characteristics. In the feeding trial, 16 pairs of Holstein–Friesian cows were used in 2 feeding systems (M1, rain-grown tropical grass pastures and oats; and M5, a feedlot, based on maize/barley silage and lucerne hay) over 2 seasons (spring and autumn corresponding to early and late lactation, respectively). Total dry matter, crude protein (kg/cow.day) and metabolisable energy (MJ/cow.day) intakes were 17, 2.7, and 187 for M1 and 24, 4, 260 for M5, respectively. M5 cows produced higher milk yields and milk with higher protein and casein levels than the M1 cows, but the total solids and fat levels were similar (P > 0.05) for both M1 and M5 cows. The yield and yield efficiency of cheese produced from the 2 feeding systems were also not significantly different. The results suggest that intensive tropical pasture systems can produce milk suitable for Cheddar cheese manufacture when cows are supplemented with a high energy concentrate. Season and stage of lactation had a much greater effect than feeding system on milk and cheesemaking characteristics with autumn (late lactation) milk having higher protein and fat contents and producing higher cheese yields.
Improved soil and irrigation management for forage production 1. Site establishment and soil physical properties
Authors: Greenwood K. L. , Mundy G. N. , Kelly K. B. , Dellow K. E. , Austin S. M.
Published: March 2006

Red-brown earths (Red Sodosols and Red Chromosols) are the dominant soil type used for irrigated forage production in northern Victoria. However, these soils have dense, clay-textured subsoils that can limit productivity. Soil modification may reduce these limitations through improving subsoil structure. In a field experiment on a Red Chromosol near Kyabram, we compared 2 systems of soil modification involving deep ripping and gypsum application (with and without subsurface drainage) with an unmodified control. Two irrigation frequencies were imposed. This paper reports on the site establishment and the soil physical responses to soil modification. Later papers detail the forage yield responses and plant–soil–water relations. Initially, both soil modification treatments improved the physical condition of the subsoil. For example, the bulk density of the modified and the drained subsoils was reduced to about 1.48 Mg/m3, compared with 1.71 Mg/m3 in the control. Soil strength was reduced in the modified and drained treatments between depths of 0.10–0.40 m at most soil water contents. In the subsoil, the modified and drained treatments had smaller soil aggregates with about 60% by weight being less than 20 mm diameter compared with 39% from the control treatment. Subsoil hydraulic conductivity, at 10 mm water tension, was 12 mm/h in the control, 33 mm/h in the modified treatment and 71 mm/h in the drained treatment when measured 1 year after the treatments were imposed. These improvements in soil physical properties generally persisted for the 2 years of measurements.
Improved soil and irrigation management for forage production 3. Plant - soil - water relationships
Authors: Mundy G. N. , Greenwood K. L. , Kelly K. B. , Austin S. M. , Dellow K. E.
Published: March 2006

A field experiment was conducted from January 2000 for 2.5 years, at the Department of Primary Industries, Kyabram, in northern Victoria. The experiment determined the effect of soil modification, with and without subsurface drainage, on the yield and water use of tall fescue (Festuca arundinacea), lucerne (Medicago sativa), phalaris (Phalaris aquatica) and perennial ryegrass (Lolium perenne) under 2 irrigation frequencies. The soil was a red-brown earth.
The forages were spray irrigated from August to May when evaporation minus rainfall (E – R) reached 45–50 mm (frequent) or 90–100 mm (infrequent). The depth of irrigation water applied was equal to the soil water deficit (SWD) of each treatment, measured before each irrigation.
Soil modification did not change the plant available water content of the soil (about 115 mm). The apparent depth of water extraction was initially different between soil management treatments but, over time, these differences disappeared. There were consistent differences between the forage species in the apparent depth of soil water extraction. Lucerne extracted water from deeper in the soil than phalaris followed by tall fescue and then perennial ryegrass. In general, the infrequently irrigated forages extracted water from deeper in the soil than did the frequently irrigated forages.
The frequently irrigated treatments received slightly more water than did the infrequent treatments. The depth of water applied to the control and modified soil was similar, whereas the drained soils received more water than did the undrained treatments. There were differences between the forages in the depth of water applied, with lucerne receiving up to about 1500 mm/year and the grasses about 1100 to 1300 mm/year. Water use efficiency [kg dry matter (DM)/ha.mm] of the forages ranged from 14 to 18 kg DM/ha.mm in 2000–01 and up to 24 kg DM/ha.mm in 2001–02. The relatively high water use efficiencies were largely due to the high yields achieved, as water use was similar to that of district farms.
Seed production of Australian native grass cultivars: an overview of current information and future research needs
Authors: Cole I. A. , Johnston W. H.
Published: March 2006

Cultivars of Australian native grasses released in the 1990s are potentially useful for improving the composition of degraded pastures, roadside revegetation and sowing in low-care amenity situations. Over 20 selections or cultivars have been identified and progressed to the stage of commercial seed increase. This review focuses on the challenge of producing high-yielding seed crops for this range of promising Australian native grasses with the aim of fostering commercial-scale seed production operations. Commercialisation of the current suite of native grass cultivars has been difficult, which is often the case for new herbage species. There are a variety of reasons for this including: (i) that experience gained in breeder’s nurseries was not directly transferable to commercial seed growers; (ii) that knowledge of the biology of many species was incomplete; (iii) a lack of basic management information for these new species; and (iv) failure to rigorously apply what is known about the seed increase of new species. Success of new cultivars as seed crops depends on addressing seed production issues as part of the overall cultivar development program, and on breeders maintaining close links with innovative commercial seed growers until the major seed production barriers are overcome and commercial seed becomes available.
Influence of applied nitrogen on growth and tissue nutrient concentration in the medicinal plant Ajowain (Trachyspermum ammi)
Authors: Ashraf M. , Noman A.
Published: March 2006

Growth performance and nutrient accumulation in Ajowain [Trachyspermum ammi (L.) Sprague] under varying levels of nitrogen were examined in a field experiment. Sixty-three-day-old plants were supplied with varying levels of N, i.e. 0, 30, 60, and 90 kg N/ha soil. Maximum biomass was recorded at 60 kg N/ha, whereas maximum seed yield was recorded at 60 and 90 kg N/ha. Shoot and root P and N increased with an increase in external N levels applied, reaching a maximum at 90 kg N/ha. However, tissue K concentration remained almost unchanged at varying soil N levels. Although accumulation of N and P in both shoots and roots of Ajowain increased consistently with an increase in soil N, this pattern of increase in the levels of 3 nutrients in plant tissues had a negative association with the growth of the crop, particularly at the higher N level (90 kg N/ha) where seed yield per plant was almost equal to that at 60 kg N/ha.
Root depth of native and sown perennial grass-based pastures, North-West Slopes, New South Wales. 1. Estimates from cores and effects of grazing treatments
Authors: Lodge G. M. , Murphy S. R.
Published: March 2006

Studies were undertaken on native and sown perennial grass-based pastures as part of the Sustainable Grazing Systems National Experiment to estimate root depth and describe root distribution in these pastures. Samples from soil cores (0–210 cm maximum sampling depth) taken in 1997 (before grazing treatments were imposed) and 4 years later in spring 2001 were used to examine the effects of different grazing regimes on root length density (cm/cm3), root mass density (mg/cm3), root volume density (cm3/cm3), and diameter (mm) at each of 3 sites. In spring 1997, mean maximum root depth was 107 cm for a native perennial grass pasture near Barraba and 74 cm for a pasture sown with phalaris (Phalaris aquatica) and subterranean clover (Trifolium subterraneum) near Nundle, with values being lower for a native pasture near Manilla (65 cm for a Brown Vertosol and 97 cm for a Red Chromosol). For all pasture types, >20% of root mass density, root length density or root volume density was in the 0–5 cm soil layer and >60% was at a depth of 0–30 cm. At all sites, mean total root mass was around 1000 kg DM/ha. After 4 years of grazing (spring 2001) there were relatively few significant effects of grazing treatment on root length density, root mass density, root volume density, or root diameter. Effects that were significant mostly occurred at 0–5 cm for the native pastures and 0–50 cm for the sown pasture. For the Barraba native pasture, root length, volume and mass densities (0–5 cm) were higher (P<0.05) in the continuously grazed, low stocking rate treatment compared with all other treatments. Similarly, for the Manilla native pasture, root length density was higher (P<0.05) in this treatment at soil depths of 0–5 and >5–10 cm compared with all other treatments. In contrast, for the Nundle sown pasture, root length density (0–5 cm) was lowest (P<0.05) in 2 continuously grazed treatments compared with those that were strategically grazed in autumn and spring.
Response of chickpea (Cicer arietinum L.) varieties to time of sowing in Mediterranean-type environments of south-western Australia
Authors: Regan K. L. , Siddique K. H. M. , Brandon N. J. , Seymour M. , Loss S. P.
Published: March 2006

Chickpea has become an important grain legume crop in Australia over the last decade. New varieties with improved seed yield and quality are being developed in Australia with varied phenological and agronomic traits. This study examined the optimum time of sowing of several desi chickpea varieties (Dooen, T1587, Sona and Tyson) varying in phenology over a range of dryland Mediterranean-type environments in south-western Australia.
Chickpea showed good adaptation, particularly in the northern grain belt of Western Australia where growing conditions are warmer than southern areas. Seed yields varied widely depending on the time of sowing, location and seasonal conditions. Mean seed yields greater than 1000 kg/ha and up to 2000 kg/ha were achieved, but in some cases seed yields were less than 800 kg/ha. In the northern region, seed yield was almost doubled by sowing in early-May (1625 kg/ha) compared with late-June (754 kg/ha). In contrast to this, seed yields were generally lower in the southern regions and greater from late-June sowings (865 kg/ha) compared to earlier mid-May sowings (610 kg/ha).
Seed yields were not clearly increased by altering sowing time to match the phenology of the variety to the growing season rainfall and temperatures, except at the early sowing times (April and early-May) where Tyson out-yielded all other varieties. This is most likely due to the lack of photoperiod-responsive, long-duration varieties to match early sowing and low temperatures limiting vegetative and reproductive growth in all varieties, especially in southern areas. However, it is likely that early flowering varieties will show greater adaptation and yield performance in short growing seasons, while later flowering varieties will be better suited to longer growing seasons.
The study found that there were significant differences in the optimum sowing time between northern, central and southern sites, based on differences in mean daily temperatures and length of the growing season. Generally, the greatest seed yields were produced by sowing between mid to late June at southern sites, and early May at central and northern sites.
Analysis of partial breakthrough data by a transfer-function method
Authors: Mojid M. A. , Rose D. A. , Wyseure G. C. L.
Published: March 2006

A transfer-function method has been applied to determine solute-transport parameters from earlier sections of complete breakthrough data. Time-domain reflectometry allows the measurement of breakthrough data in unsaturated soil. In fine-textured soils, the flow of water must be kept low to maintain unsaturated conditions, and so experiments for a complete breakthrough of solute may last a very long time. Substantial savings of time and computer memory might be achieved if data could be analysed from an earlier section of breakthrough data. Data at 2 vertical positions (input at upper and response at lower position) from a complete breakthrough of calcium chloride applied as a pulse input to 4 unsaturated soils (coarse sand, sandy loam, clay loam, clay) were divided into 4 sets of increasing duration. Transport parameters of calcium chloride were determined by a transfer function, which results in similar values of the parameters from the last 3 datasets in all 4 soils. In the clay soil, however, because of erroneous breakthrough data the fit between the measured and estimated breakthrough curves (BTCs) was poor, but the transport parameters were consistent among different segments of data. We show that it is possible to determine successfully solute-transport parameters from partial breakthrough data, which include the peak of the response BTC. This transfer-function method is thus a powerful tool to shorten breakthrough experiments.
Nutrient leaching and changes in soil characteristics of four contrasting soils irrigated with secondary-treated municipal wastewater for four years
Authors: Sparling G. P. , Barton L. , Duncan L. , McGill A. , Speir T. W. , Schipper L. A. , Arnold G. , Van Schaik A.
Published: March 2006

Land treatment is the preferred option for the disposal of wastewater in New Zealand. We applied secondary-treated municipal wastewater to 4 contrasting soils (a Gley, Pumice, Recent, and Allophanic Soil) at the rate of 50 mm per week, for 4 years. Amounts of N and P in applied wastewater, leachates, and removed in herbage were measured every 1–4 weeks, and a range of soil chemical, biochemical and physical characteristics measured by destructive sampling after 2 and 4 years. After 4 years, leaching losses amounted to 290–307 kg N on the Gley and Recent Soils, representing approximately 22% of the N applied. Leaching losses from the Allophanic and Pumice Soils were 44 and 69 kg N/ha, respectively, representing <5% of that applied. More than half of the N leached was in organic forms. Leaching losses of P were <5 kg P/ha on the Pumice and Allophanic Soils (< 1% of that applied), 41 kg P/ha from the Recent Soil and 65 kg P/ha from the Gley Soil (8% and 13% of that applied, respectively). After 4 years, the total C and microbial C content in the A horizon of the irrigated Recent Soil were, respectively, 47% and 44% less than non-irrigated cores. All irrigated soils showed a rise in pH of up to 1 unit, and all had a marked increase in the exchangeable Na+ which reached 4–22% ESP. After 4 years, the saturated and near saturated hydraulic conductivity of the Gley Soil had declined from 567 and 40 mm/h to 56 and 3 mm/h, respectively. Allophanic and Pumice Soils are to be preferred over the Recent and Gley Soils for effective treatment of wastewater and to minimise the loss of nutrients to the wider environment.
Spatial and time-dependent patterns of selenium (Se) release from selected Se fertiliser granules
Authors: Loganathan P. , Hedley M. J.
Published: March 2006

The spatial and time-dependent patterns of selenium (Se) release from similar-sized granules of 4 Se fertilisers, 3 containing sodium selenate (Unitech Agsel, Ravensdown A, and Ravensdown B) and the fourth containing sodium selenate and barium selenate (Selcote Ultra), were evaluated using ryegrass grown on a Se-deficient soil under glasshouse conditions. Four granules (2–3 mm diameter) from each of the 4 fertiliser types having uniform shape and similar weight were placed on the soil surface of trays (0.51 m length, 0.42 m width, 0.15 m depth) at a distance 0.10 m from 2 adjacent sides of the trays, and the Se content of herbage in concentric rings around each granule was periodically measured over 1 year. The amount of Se applied to the trays, calculated by adding herbage Se to the residual fertiliser Se in soil at the end of the trial, was 12–31 g Se/ha.
Soil Se concentration at the end of the trial for the Selcote Ultra and Ravensdown A treatments and herbage Se concentration at 10 harvests for all fertiliser treatments decreased exponentially with increased distance from the granules. Herbage Se concentration reached the level considered deficient to animals (0.05 mg/kg) at the centre of the tray (0.12 m from the granules) 4 months after Unitech Agsel application (7% of paddock area). By 9 months all plants in this treatment became deficient in Se. In contrast, 7% of the sward area in the Ravensdown A treatment, and 41% of the sward area in the Ravensdown B and Selcote Ultra treatments, were deficient in Se at this time, but the average herbage Se concentration for the entire tray was above the deficiency level for these 3 fertiliser treatments.
The efficiency of the fertilisers in increasing herbage Se concentration per unit weight of Se applied for the first 3 months was: Unitech Agsel ≥ Ravensdown B ≥ Ravensdown A > Selcote Ultra. During the last 3 months, this order was: Selcote Ultra = Ravensdown A > Ravensdown B > Unitech Agsel.
New primate genus from the Miocene of Argentina
Authors: Tejedor Marcelo F. , Tauber Adán A. , Rosenberger Alfred L. , Swisher Carl C. , Palacios María E.
Published: March 2006

Killikaike blakeiis a new genus and species of anthropoid from the late Early Miocene of southeastern Argentina based on the most pristine fossil platyrrhine skull and dentition known so far. It is part of the New World platyrrhine clade (Family Cebidae; Subfamily Cebinae) including modern squirrel (Saimiri) and capuchin monkeys (Cebus) and their fossil relatives known from Early to Middle Miocene and subrecent periods. Living cebines are relatively large-brained, adroit predatory foragers and live within complex social groups, and wild capuchins exhibit a wide range of behaviors associated with enhanced intelligence. We show thatK. blakeilacks diagnostic derived characteristics of the lower face and premolar dentition that are shared by modern cebines, but its strongly vaulted frontal bone and capacious anterior cranial fossa indicate the early evolution of an enlarged forebrain.
A simple artificial light-harvesting dyad as a model for excess energy dissipation in oxygenic photosynthesis
Authors: Berera Rudi , Herrero Christian , van Stokkum Ivo H. M. , Vengris Mikas , Kodis Gerdenis , Palacios Rodrigo E. , van Amerongen Herbert , van Grondelle Rienk , Gust Devens , Moore Thomas A. , Moore Ana L. , Kennis John T. M.
Published: March 2006

Under excess illumination, plant photosystem II dissipates excess energy through the quenching of chlorophyll fluorescence, a process known as nonphotochemical quenching. Activation of nonphotochemical quenching has been linked to the conversion of a carotenoid with a conjugation length of nine double bonds (violaxanthin) into an 11-double-bond carotenoid (zeaxanthin). It has been suggested that the increase in the conjugation length turns the carotenoid from a nonquencher into a quencher of chlorophyll singlet excited states, but unequivocal evidence is lacking. Here, we present a transient absorption spectroscopic study on a model system made up of a zinc phthalocyanine (Pc) molecule covalently linked to carotenoids with 9, 10, or 11 conjugated carbon–carbon double bonds. We show that a carotenoid can act as an acceptor of Pc excitation energy, thereby shortening its singlet excited-state lifetime. The conjugation length of the carotenoid is critical to the quenching process. Remarkably, the addition of only one double bond can turn the carotenoid from a nonquencher into a very strong quencher. By studying the solvent polarity dependence of the quenching using target analysis of the time-resolved data, we show that the quenching proceeds through energy transfer from the excited Pc to the optically forbidden S
1
state of the carotenoid, coupled to an intramolecular charge-transfer state. The mechanism for excess energy dissipation in photosystem II is discussed in view of the insights obtained on this simple model system.
Suppression of natural killer cell-mediated bone marrow cell rejection by CD4+CD25+regulatory T cells
Authors: Barao Isabel , Hanash Alan M. , Hallett William , Welniak Lisbeth A. , Sun Kai , Redelman Doug , Blazar Bruce R. , Levy Robert B. , Murphy William J.
Published: March 2006

Naturally occurring CD4+CD25+T regulatory (Treg) cells have been shown to inhibit adaptive responses by T cells. Natural killer (NK) cells represent an important component of innate immunity in both cancer and infectious disease states. We investigated whether CD4+CD25+Treg cells could affect NK cell functionin vivoby using allogeneic (full H2-disparate) bone marrow (BM) transplantation and the model of hybrid resistance, in which parental marrow grafts are rejected solely by the NK cells of irradiated (BALB/c × C57BL/6) F1recipients. We demonstrate that the prior removal of host Treg cells, but not CD8+T cells, significantly enhanced NK cell-mediated BM rejection in both models. The inhibitory role of Treg cells on NK cells was confirmedin vivowith adoptive transfer studies in which transferred CD4+CD25+cells could abrogate NK cell-mediated hybrid resistance. Anti-TGF-β mAb treatment also increased NK cell-mediated BM graft rejection, suggesting that the NK cell suppression is exerted through TGF-β. Thus, CD4+CD25+Treg cells can potently inhibit NK cell functionin vivo, and their depletion may have therapeutic ramifications for NK cell function in BM transplantation and cancer therapy.