bluuebunny/crossref_metadata_2025 huggingface dataset:
Properties of fluid deuterium under double-shock compression to several Mbar
Authors: Boehly T. R. , Hicks D. G. , Celliers P. M. , Collins T. J. B. , Earley R. , Eggert J. H. , Jacobs-Perkins D. , Moon S. J. , Vianello E. , Meyerhofer D. D. , Collins G. W.
Published: August 2004

The compressibility of fluid deuterium up to several Mbar has been probed using laser-driven shock waves reflected from a quartz anvil. Combining high-precision (∼1%) shock velocity measurements with the double-shock technique, where differences in equation of state (EOS) models are magnified, has allowed better discrimination between theoretical predictions in the second-shock regime. Double-shock results are in agreement with the stiffer EOS models—which exhibit roughly fourfold single-shock compression—for initial shocks up to 1 Mbar and above 2 Mbar, but diverge from these predictions in between. Softer EOS models—which exhibit sixfold single-shock compression at 1 Mbar—overestimate the reshock pressure for the entire range under study.
Surfactant effect of gallium during the growth of GaN on AlN(0001¯) by plasma-assisted molecular beam epitaxy
Authors: Gogneau N. , Sarigiannidou E. , Monroy E. , Monnoye S. , Mank H. , Daudin B.
Published: August 2004

The growth mode of N-face GaN deposited on AlN(0001¯) by plasma-assisted molecular beam epitaxy has been investigated. Based on reflection high-energy electron diffraction experiments, we demonstrate that for appropriate Ga fluxes and substrate temperature, a self-regulated 1-ML-thick Ga excess film can be formed on the growing surface. Depending on the presence of this Ga monolayer, the growth can proceed following either the Stranski–Krastanow or the Frank Van der Merwe growth modes, hence enabling the synthesis of either quantum dots or quantum wells.
Direct measurement of proton-beam-written polymer optical waveguide sidewall morphorlogy using an atomic force microscope
Authors: Sum T. C. , Bettiol A. A. , Seng H. L. , Kan J. A. van , Watt F.
Published: August 2004

Proton-beam writing (PBW) is a direct-write micromachining technique capable of fabricating low-loss single-mode polymer waveguides with straight and smooth sidewalls. Recently, the sidewall morphologies of such proton beam written polymer waveguide structures were directly measured using an atomic force microscope (AFM). Statistical information such as the rms roughness and the correlation length of the sidewall profile obtained from the AFM scans allows us to quantify the quality of the sidewalls and optimize the fabrication parameters using PBW. For structures fabricated using a stage scanning speed of ∼10μm∕s, a rms roughness of 3.8±0.3nm with a correlation length of 46±6nm was measured.
Vertical nanowire transistors with low leakage current
Authors: Chen J. , Klaumünzer S. , Lux-Steiner M. C. , Könenkamp R.
Published: August 2004

A vertical field-effect transistor based on semiconductor nanowires is reported. The fabrication of the device uses a self-supporting flexible nanostructured polymer foil as a template and an electrochemical growth technique for the preparation of the semiconductor. The fabrication process is substantially simpler, and the mechanical robustness is strongly increased as compared to the original device. The channel region of the transistor has a diameter of ∼100nm and a length of ∼50nm. Operation in the hole depletion mode allows a change of the transfer conductance by ∼50% when the gate voltages is changed in the range ∓1V. The gate leakage current is ∼600fA per transistor. The overall layout is suitable for optical pixel control on large-area flexible substrates.
Measurement of positive gain on the 1315nm transition of atomic iodine pumped by O2(a1Δ) produced in an electric discharge
Authors: Carroll D. L. , Verdeyen J. T. , King D. M. , Zimmerman J. W. , Laystrom J. K. , Woodard B. S. , Richardson N. , Kittell K. , Kushner Mark J. , Solomon W. C.
Published: August 2004

Laser action at 1315nm on the I(P1∕22)→I(P3∕22) transition of atomic iodine is conventionally obtained by a near-resonant energy transfer from O2(a1Δ), which is produced using wet-solution chemistry. The system difficulties of chemically producing O2(a1Δ) has motivated investigations into gas phase methods to produce O2(a1Δ) using low-pressure electric discharges. In this letter we report on positive gain on the 1315nm transition of atomic iodine where the O2(a1Δ) was produced in a flowing electric discharge. The electric discharge was followed by a continuously flowing supersonic cavity that was necessary to lower the temperature of the flow and shift the equilibrium of atomic iodine more in favor of the I(P1∕22) state. A tunable diode laser system capable of scanning the entire line shape of the (3,4) hyperfine transition of iodine provided the measurements of gain.
Impact ionization coefficients of 4H silicon carbide
Authors: Hatakeyama T. , Watanabe T. , Shinohe T. , Kojima K. , Arai K. , Sano N.
Published: August 2004

Anisotropy of the impact ionization coefficients of 4H silicon carbide is investigated by means of the avalanche breakdown behavior of p+n diodes on (0001) and (112¯0) 4H silicon carbide epitaxial wafers. The impact ionization coefficients are extracted from the avalanche breakdown voltages and the multiplication of a reverse leakage current, due to impact ionization of these p+n diodes. The breakdown voltage of a p+n diode on a (112¯0) wafer is 60% of that on a (0001) wafer, and the extracted impact ionization coefficients of 4H silicon carbide show large anisotropy. We have shown that the anisotropy of the impact ionization coefficients is related to the anisotropy of carrier heating and drift velocity, which are due to the highly anisotropic electronic structure of 4H silicon carbide.
Heat-assisted magnetization switching in elongated submicrometer Permalloy structures
Authors: Atkinson D. , Cowburn R. P.
Published: August 2004

The effect on switching behavior of locally heating individual Permalloy nanostructures is reported. The samples consisted of isolated magnetic structures with an aluminum conducting strip on top at one end of each structure, through which direct current passed to heat the nanostructure. Magnetization switching in individual nanostructures was detected using the magneto-optic Kerr effect. The average coercivity fell with increasing current in the aluminum strip by up to 20%, but, interestingly, the change in absolute magnitude of the coercivity was similar for nanowires of different width for current densities approaching 1011Am−2 in the aluminum conductor. The temperature rise at this current density is less than 40K.
Recrystallization texture, epitaxy, and magnetic properties of electrodeposited FePt on Cu(001)
Authors: Svedberg Erik B. , Mallett Jonathan J. , Sayan Safak , Shapiro Alexander J. , Egelhoff William F. , Moffat Thomas
Published: August 2004

A near-equiatomic FePt face-centered-cubic alloy has been grown by electrodeposition onto Cu(001). Annealing at 450°C results in the onset of a A1 fcc to L10 face-centered-tetragonal phase transformation with a dominant FePt(001)⟨100⟩‖Cu(001)⟨100⟩ recrystallization texture, possibly driven by the reduced ordering temperature in an FePtCu intermixed interface region. Further annealing at 650°C leads to a more complete transformation, and magnetic measurements indicate that high perpendicular coercivities, of up to 10kOe, are accessible through the recrystallization reaction. The magnetic and structural properties reported in this work may allow electrodeposited FePt to play a leading role in future ultrahigh-density patterned perpendicular magnetic media.
Spatial correlation-anticorrelation in strain-driven self-assembled InGaAs quantum dots
Authors: Wang X.-D. , Liu N. , Shih C. K. , Govindaraju S. , Holmes A. L.
Published: August 2004

We report evidence for the existence of anticorrelation in InGaAs∕GaAs self-assembled quantum dots (QDs). We found that, as a function of the spacer layer thickness, the QDs between the neighboring layers are either vertically correlated (at small spacer thickness) or anticorrelated (at larger spacer thickness). Moreover, in the case when the QDs are antialigned, the size distribution of individual quantum dots becomes more uniform. The implications of this work to the fundamental understanding of the self-assembly process, and the technological applications are discussed.
Ultraviolet light-emitting diodes operating in the 340nm wavelength range and application to time-resolved fluorescence spectroscopy
Authors: Peng H. , Makarona E. , He Y. , Song Y.-K. , Nurmikko A. V. , Su J. , Ren Z. , Gherasimova M. , Jeon S.-R. , Cui G. , Han J.
Published: August 2004

We report on the development of UV light-emitting diodes in the 340nm wavelength range, based on quaternary AlGaInN quantum-well active media. Output powers up to 1mW from small area devices (<100μm diameter) directly off a planar chip have been achieved. The devices have been operated as subnanosecond pulsed sources to demonstrate their applicability to compact time-resolved fluorescence spectroscopy.
Cathodoluminescence versus dynamical epitaxy of Ba-ion irradiated α-quartz
Authors: Dhar S. , Gąsiorek S. , Sahoo P. K. , Vetter U. , Hofsäß H. , Kulkarni V. N. , Lieb K. P.
Published: August 2004

Doping α-quartz with photoactive ions without destroying its crystalline structure appears to be a promising way to tune its luminescent and structural properties. We have achieved dynamic solid phase epitaxial regrowth and cathodoluminescence of 175keV Ba-ion irradiated α-quartz in the temperature range from 300 to 1170K. Rutherford Backscattering Channeling analysis showed that the amorphous layer produced by 1×1015 Baions∕cm2 at 300K had almost disappeared at an implantation temperature of 1123K. Room temperature cathodoluminescence exhibited dramatic changes in the optical spectra as a function of the implantation temperature and allowed to distinguish between color centers related to quartz, ion-irradiated silica and implanted Ba. Between 770 and 1100K, room-temperature cathodoluminescence showed a predominant blue and other weak bands connected to various known defects in the Si-O-Si network. However, after achieving almost complete solid phase epitaxial recovery, only a violet band at 3.4eV remained, which we attribute to Ba-related luminescence centers.
Microreflectivity characterization of the two-dimensional refractive index distribution of electron-beam-written optical waveguides in germanium-doped flame-hydrolysis silica
Authors: Blanco S. García , Aitchison J. S. , Hnatovsky C. , Taylor R. S.
Published: August 2004

In this letter, we report on the detailed refractive index distribution of optical waveguides induced by electron-beam irradiation of Ge-doped flame hydrolysis silica and its variation with dose. The characterization was performed using microreflectivity measurements.
Infrared surface plasmons in two-dimensional silver nanoparticle arrays in silicon
Authors: Mertens H. , Verhoeven J. , Polman A. , Tichelaar F. D.
Published: August 2004

We present two-dimensional arrays of silver nanoparticles embedded in amorphous silicon, fabricated by a sequential Si∕Ag∕Si electron-beam evaporation process. The particle arrays exhibit surface plasmon resonance spectra in the near-infrared (0.9eV), with tails extending below 0.5eV. The data are compared with calculations that take into account measured particle size, shape anisotropy, and separation. It is concluded that the large redshift is mainly due to the high refractive index of the matrix, with shape anisotropy and interparticle coupling contributing several tenths of an electron volt. This work enables plasmon-related applications at the telecommunication wavelength of 1.5μm(0.8eV).
Field emission of zinc oxide nanowires grown on carbon cloth
Authors: Jo S. H. , Banerjee D. , Ren Z. F.
Published: August 2004

An extremely low operating electric field has been achieved on zinc oxide (ZnO) nanowire field emitters grown on carbon cloth. Thermal vaporization and condensation was used to grow the nanowires from a mixture source of ZnO and graphite powders in a tube furnace. An emission current density of 1mA∕cm2 was obtained at an operating electric field of 0.7V∕μm. Such low field results from an extremely high field enhancement factor of 4.11×104 due to a combined effect of the high intrinsic aspect ratio of ZnO nanowires and the woven geometry of carbon cloth.
Band-gap modified Al-doped Zn1−xMgxO transparent conducting films deposited by pulsed laser deposition
Authors: Matsubara K. , Tampo H. , Shibata H. , Yamada A. , Fons P. , Iwata K. , Niki S.
Published: August 2004

Al-doped Zn1−xMgxO films have been deposited on glass substrates at a substrate temperature of 200°C by a pulsed laser deposition system. A resistivity of 3×10−4Ωcm was obtained at x=0.06. Film resistivity was found to increase with further increases in Mg composition. The maximum band gap of films with a resistivity ρ⩽1×10−3Ωcm was found to be 3.97eV, demonstrating band-gap engineering possibilities in the range of Eg=3.5–3.97eV with a resistivity ρ⩽1×10−3Ωcm. The average transmittance of the films was higher than 90% in the wavelength region λ=400–800nm, a range suitable for transparent conducting film applications.
Switchable reflectivity on silicon from a composite VO2-SiO2 protecting layer
Authors: Lopez R. , Boatner L. A. , Haynes T. E. , Haglund R. F. , Feldman L. C.
Published: August 2004

Surfaces whose reflectivity can be thermally controlled were formed on single crystals of silicon by using ion beams to create a nanocomposite layer consisting of VO2 precipitates embedded in a thin-film matrix of amorphous SiO2. The surface nanocomposite layer was produced by first thermally oxidizing a Si crystal to produce an overlying SiO2 film with a desired thickness. Stoichiometric coimplantation of vanadium and oxygen ions and subsequent thermal processing were then employed to form embedded VO2 nanoparticles in the SiO2 film. The reflectivity of the vanadium dioxide particles undergoes large changes at the VO2 semiconductor-to-metal phase transition, thereby providing the mechanism for thermally controlling the reflectivity of the VO2∕SiO2∕Si layer and, effectively, the Si crystal surface. The VO2∕SiO2 nanocomposite layer was applied in a device configuration in which heating via current through the Si substrate is used to control the surface reflectivity.
Influence of intensive light exposure on polymer field-effect transistors
Authors: Ficker J. , von Seggern H. , Rost H. , Fix W. , Clemens W. , McCulloch I.
Published: August 2004

The influence of intensive light exposure on high performance polymer field-effect transistors containing highly regioregular poly(3-alkylthiophene) as a semiconductor is reported. While the transistors show high stability under ambient air and light, a distinct degradation upon exposure to intensive light could be detected by its impact on the on currents. UV-Vis spectra were used to interpret the current decrease as being caused by a decrease of the conjugation length of the semiconductor, which is supported by IR spectrometry. The role of ambient air, in particular, oxygen, in the degradation process is shown.
Formation of dynamic holograms based on spatial modulation of molecular motions of ferroelectric liquid crystals
Authors: Sasaki Takeo , Mochizuki Oki , Nakazawa Yukihito , Fukunaga Godai , Nakamura Tetsuya , Noborio Kazunori
Published: August 2004

The formation of dynamic holograms based on the spatial modulation of the molecular motions of ferroelectric liquid crystals (FLCs) was demonstrated. The consecutive rotational switching motion of FLC molecules under an alternating electric field was modulated by the photoinduced additional electric field built at the interference fringe. This spatially periodic difference in molecular motions of an FLC was confirmed to work as a diffraction grating. Since the motion-mode hologram is stable and the response is very fast when compared to photorefractive polymers, the motion-mode hologram appears to be promising for various photonic applications.
Electron accumulation layer at the Cs-covered GaN(0001) n-type surface
Authors: Benemanskaya G. V. , Vikhnin V. S. , Shmidt N. M. , Frank-Kamenetskaya G. E. , Afanasiev I. V.
Published: August 2004

We report on the observation of photoemission from the Cs∕GaN(0001) n-type interface by excitation of visible light in the transparency region of GaN. Under Cs adsorption, sharp decrease in photoemission threshold up to 1.3eV at 0.5 monolayer of Cs is found and shown to be due to formation of a charge accumulation layer in the near-interface region. An interesting phenomenon is revealed, namely, the appearance of an oscillation structure in spectra of photoyield. A model conception taking into account both the formation of charge accumulation layer and occurrence of multiple-beam interference in parallel-sided GaN epilayer is suggested.
Mechanical model for the generation of acoustic chaos in sonic infrared imaging
Authors: Han Xiaoyan , Loggins V. , Zeng Zhi , Favro L. D. , Thomas R. L.
Published: August 2004

We describe a mechanical model for the generation of complex vibrations with fractional “subharmonics” from the contact between a sharply tuned ultrasonic source and a rigid object. The frequency patterns generated by the model mimic the patterns observed in samples undergoing sonic IR imaging. The output of the model is chaotic in the sense that the output appears to lack continuity with respect to the input parameters.
Surface cleaning and annealing effects on Ni∕AlGaN interface atomic composition and Schottky barrier height
Authors: Bradley S. T. , Goss S. H. , Hwang J. , Schaff W. J. , Brillson L. J.
Published: August 2004

Internal photoemission spectroscopy reveals changes in the Schottky barrier height of Ni on AlGaN∕GaN high electron mobility transistor structures with premetallization processing conditions and postmetallization ultrahigh-vacuum annealing. These variations in the internal photoemission Schottky barrier height are correlated with AlGaN near-band-edge emissions from low-energy electron-excited nanoluminescence spectroscopy and Ni∕AlGaN interface impurities by secondary ion mass spectrometry. We show that changes in the Schottky barrier height and the appearance of dual barriers are dominated by changes in the local Al mole fraction. Interfacial oxygen and carbon have secondary but systematic effects as well.
InAs
∕
InP
quantum dots emitting in the 1.55μm wavelength region by inserting submonolayer GaP interlayers
Authors: Gong Q. , Nötzel R. , van Veldhoven P. J. , Eijkemans T. J. , Wolter J. H.
Published: August 2004

We report on the growth of InAs quantum dots (QDs) in GaInAsP on InP (100) substrates by chemical-beam epitaxy, with emission wavelength in the 1.55μm region. Submonolayer coverage of GaP on the GaInAsP buffer before deposition of the InAs QDs results in most efficient suppression of As∕P exchange during InAs growth and subsequent growth interruption under arsenic flux. Continuous wavelength tuning from above 1.6 to below 1.5μm is thus achieved by varying the coverage of the GaP interlayer within the submonolayer range. Temperature dependent photoluminescence reveals distinct zero-dimensional carrier confinement and indicates that the InAs QDs are free of defects and dislocations.
Near-field polarimetric characterization of polymer crystallites
Authors: Goldner Lori S. , Goldie Scott N. , Fasolka Michael J. , Renaldo Francoise , Hwang Jeeseong , Douglas Jack F.
Published: August 2004

We use near-field polarimetry (NFP) to investigate thin-film crystallites of isotactic polystyrene (iPS). NFP micrographs enable quantitative optical characterization of the birefringence in these specimens with subdiffraction-limited resolution, resulting in observations that give: (1) evidence for radial strain in the depletion boundary surrounding the growth front, and (2) a map of local tilt in the crystal axis and/or strain in the amorphous layers above and below the growth plane of the crystallites.
Above-room-temperature ferromagnetic Ni2+-doped ZnO thin films prepared from colloidal diluted magnetic semiconductor quantum dots
Authors: Schwartz Dana A. , Kittilstved Kevin R. , Gamelin Daniel R.
Published: August 2004

We report the preparation of spin-coated nickel-doped zinc oxide nanocrystalline thin films using high-quality colloidal diluted magnetic semiconductor (DMS) quantum dots as solution precursors. These films show robust ferromagnetism with Curie temperatures above 350K and 300K saturation moments up to 0.1Bohr magnetons per nickel. These results demonstrate a step toward the use of colloidal zero-dimensional DMS nanocrystals as building blocks for the bottom-up construction of more complex ferromagnetic semiconductor nanostructures.
Size control of InAs∕InP(001) quantum wires by tailoring P∕As exchange
Authors: Fuster David , González María Ujué , González Luisa , González Yolanda , Ben Teresa , Ponce Arturo , Molina Sergio I. , Martínez-Pastor Juan
Published: August 2004

The size and emission wavelength of self-assembled InAs∕InP(001) quantum wires (QWrs) is affected by the P∕As exchange process. In this work, we demonstrate by in situ stress measurements that P∕As exchange at the InAs∕InP interface depends on the surface reconstruction of the InAs starting surface and its immediate evolution when the arsenic cell is closed. Accordingly, the amount of InP grown on InAs by P∕As exchange increases with substrate temperature in a steplike way. These results allow us to engineer the size of the QWr for emission at 1.3 and 1.55μm at room temperature by selecting the range of substrate temperatures in which the InP cap layer is grown.
Lasing characteristics of InAs quantum-dot microdisk from 3K to room temperature
Authors: Ide Toshihide , Baba Toshihiko , Tatebayashi Jun , Iwamoto Satoshi , Nakaoka Toshihiro , Arakawa Yasuhiko
Published: August 2004

We fabricated a microdisk laser with five-stacked InAs quantum-dot (QD) active region, and demonstrated the lasing operation from 3K to room temperature by femtosecond pulsed photopumping. At room temperature, the threshold power was estimated to be 0.75mW, when the influence of the surface recombination at the disk edge was neglected. The lasing wavelength was 1.2–1.3μm, which corresponded to excited states of the QDs. The temperature dependence of the threshold, slope efficiency, lasing wavelength, and linewidth are explained by the rapid increase in nonradiative recombination and internal absorption at critical temperatures of 200–230K.
Carbon nanotube alignment by surface acoustic waves
Authors: Strobl C. J. , Schäflein C. , Beierlein U. , Ebbecke J. , Wixforth A.
Published: August 2004

We present a realization of carbon nanotube alignment. Surface acoustic waves are applied to a multiwalled carbon nanotube suspension and the lateral piezoelectric field of the standing wave aligns the carbon nanotubes with an angle of 25° to 45° on LiNbO3 with respect to the direction of wave propagation. This angle results from a superposition of the aligning electric field and a perpendicular fluidic flux in the carbon nanotube suspension caused by the energy transfer from the surface acoustic wave into the liquid. On LiTaO3, the multiwalled carbon nanotubes align parallel to the wave vector due to negligible fluidic processes.
High-performance magnetic field sensor based on superconducting quantum interference filters
Authors: Caputo P. , Oppenländer J. , Häussler Ch. , Tomes J. , Friesch A. , Träuble T. , Schopohl N.
Published: August 2004

We have developed an absolute magnetic field sensor using a superconducting quantum interference filter (SQIF) made of high-Tc grain-boundary Josephson junctions. The device shows the typical magnetic-field-dependent voltage response V(B), which is a sharp deltalike dip in the vicinity of zero-magnetic field. When the SQIF is cooled with magnetic shield, and then the shield is removed, the presence of the ambient magnetic field induces a shift of the dip position from B0≈0 to a value B≈B1, which is about the average value of the Earth’s magnetic field, at our latitude. When the SQIF is cooled in the ambient field without shielding, the dip is first found at B≈B1, and the further shielding of the SQIF results in a shift of the dip towards B0≈0. The low hysteresis observed in the sequence of experiments (less than 5% of B1) makes SQIFs suitable for high precision measurements of the absolute magnetic field. The experimental results are discussed in view of potential applications of high-Tc SQIFs in magnetometry.
Ecology of Nassella neesiana, Chilean needle grass, in pastures on the Northern Tablelands of New South Wales. I. Seed production and dispersal
Authors: Gardener M. R. , Whalley R. D. B. , Sindel B. M.
Published: August 2004

Nassella neesiana (Trin. & Rupr.) Barkworth (Chilean needle grass) originated in South America and is now a widespread weed in pastures in south-eastern Australia. To date, little research on the biology of N.�neesiana has been undertaken in Australia. This study investigated several aspects of the biology of N. neesiana in pastures on the Northern Tablelands of New South Wales. The main flowering period for N. neesiana in Australia was shown to extend from November to February and is similar to that in South America. Potential for production of panicle seeds was large and varied from 1584 seeds/m2 in 1995 to 22 203 seeds/m2 in 1996 as a result of changes in the density of flowering tillers per unit area. Nassella neesiana produced a further 7.2 cleistogenes (hidden seeds in the flower stem) on average per tiller. Hence, total potential seed production (panicle seeds and cleistogenes) was 28 282 and 8036 seeds/m2 in 1996 and 1997, with the cleistogenes accounting for 21.5 and 26.1% of the total respectively. Furthermore, the production of cleistogenes was not affected by clipping flowering tillers at 3 different heights. Three possible dispersal mechanisms of N. neesiana seeds were investigated. Adherence of seeds to the wool appeared to be the most effective. Twenty-five per cent of seeds that were picked up naturally in the wool of sheep after grazing in a paddock of N. neesiana, remained after 5 months. Shearing just before seed set reduced the number of seeds adhering to the wool. An average of 1.7% of panicle seeds and 5.3% of cleistogenes fed to Angus steers passed through the animal intact within 4 days, but <50% of these seeds were viable. The majority of seeds recovered from a wind dispersal experiment were within 1 m of the parent plant and the furthermost seed was 2.8 m away. The implications of these results for management are discussed.
Effects of supplement type and previous experience on variability in intake of supplements by heifers
Authors: Dixon R. M. , White A. , Fry P. , Petherick J. C.
Published: August 2004

Intakes, and variability in intakes, of a range of supplements were examined in groups (n = 10–20) of cattle grazing tropical native pasture in 24-ha paddocks. Intakes of supplement by individual animals were measured using lithium sulfate as a marker. In Expt 1, heifers (n = 160) were offered 1 of 4 supplements consisting of (i) a restricted amount of cottonseed meal (CSM); or ad libitum amounts of (ii) molasses containing 74 g urea/kg (M8U), (iii) a loose mineral mix (LMM) containing (g/kg) salt 390, urea 300, CSM 150, calcium phosphate 150, and sulfur 10, and (iv) feed block supplements containing (g/kg) molasses 494, urea 99, calcium phosphate 62, salt 62, bran 62, calcium oxide 148, and magnesium oxide 74. After 5 and 10 weeks the variation in supplement intake among heifers within a group was lower (P < 0.05) for CSM and M8U (coefficient of variation (CV) 24–37%) than for the LMM or block supplements (CV 55–118%). All heifers offered CSM or M8U consumed at least some supplement, but up to 5% and 20% of heifers were non-eaters of LMM or block supplement, respectively. Both the per�cent non-eaters of supplement and the variability in intake of these latter supplements tended (P < 0.10) to decline as the experiment progressed. In Expt 2 the same heifers were re-allocated to paddock groups and were offered ad libitum supplements of (i) M8U, (ii) molasses containing 107 g urea/kg (M12U), (iii) M8U mixed with monensin (M8U-M), or (iv) M8U mixed with meatmeal (M8U-MM). The CV of supplement intake ranged from 37 to 58%, and except in one paddock group offered M8U-MM, all heifers consumed at least some supplement. In Expt�3, paddock groups of heifers (n = 120) without, or with experience of LMM supplements during the previous dry season were offered LMM supplements containing either nil or 300�g CSM/kg. Voluntary intake of LMM supplement DM was increased (P < 0.001) by 93% by inclusion of CSM and decreased (P < 0.05) by 24% by previous experience of a similar LMM supplement. Neither variability in supplement intake (CV 66–150%) nor the per�cent non-eaters was significantly (P > 0.05) affected by previous experience of the heifers with LMM supplements or inclusion of CSM in the supplement. However, the per cent non-eaters of LMM supplement was inversely related to the mean voluntary intake of the supplement by the paddock group; when the average voluntary intake of the supplement by the paddock group exceeded 0.2 g DM/kg LW.day, then ≤10% of heifers were non-eaters of supplement. In conclusion, within groups of heifers offered LMM and block supplements the variability in intake and per cent non-eaters of supplement were higher than for cottonseed meal or molasses-urea supplements, and variability appeared to be associated with voluntary intake of the supplements.
Meat texture of lambs from different European production systems
Authors: Sañudo C. , Alfonso M. , Sanchez A. , Berge P. , Dransfield E. , Zygoyiannis D. , Stamataris C. , Thorkelsson G. , Valdimarsdottir T. , Piasentier E. , Mills C. , Nute G. R. , Fischer A. V.
Published: August 2004

Measurements of meat texture (Warner-Bratzler shear force, WBSF), compression stress at 20% (S20) and 80% (S80) of initial sample thickness, sarcomere length, pH, and sensory tenderness score were determined on the longissimus muscle from lambs from 22 diverse European lamb types from 6 countries. Carcasses chilled to minimise cold shortening. The types ranged from 1-month-old milk-fed lambs to 1-year-old heavy wether lambs reared on the transhumance system (extensive system based on moving animals from valleys to high mountains in search of seasonal resources). Overall, it seems that breed was more important in influencing meat toughness than age or gender. Within breed, there was some evidence of an age effect (the older the animal the tougher the meat), and nutritional handling was, in some cases, significant. The lowest WBSF values were for meat from 16-kg carcasses of pasture-fed animals of the Icelandic breed (average 1.7 kg) and the highest were for meat from 19–20 kg carcasses of the Bergamasca breed (average 4.1 kg). The two youngest types had the highest values for S20 (10.5 and 11.8 N/cm2), the compression value related to myofibrillar component. There was a very good agreement between panels from the different countries in the ranking of tenderness; meat from the Icelandic breed was the most tender and that from the Bergamasca breed the least, in concurrence with the WBSF results, with a significant relationship between tenderness and WBSF values in all the lamb types studied.
Gaseous nitrogen loss from temperate perennial grass and clover dairy pastures in south-eastern Australia
Authors: Eckard R. J. , Chen D. , White R. E. , Chapman D. F.
Published: August 2004

The use of nitrogen (N) fertiliser on dairy pastures in south-eastern Australia has increased exponentially over the past 15 years. Concerns have been raised about the economic and environmental impact of N loss through volatilisation and denitrification. Emissions of NH3, N2, and N2O were measured for 3 years in the 4 different seasons from a grazed grass/clover pasture, with or without 200 kg N fertiliser/ha, applied as ammonium nitrate and urea.Nitrogen-fertilised treatments lost significantly more N than the control treatments in all cases. More NH3 was lost from urea-fertilised treatments than from either the control or ammonium nitrate treatments, whereas ammonium nitrate treatments lost significantly more N through denitrification than the control or urea treatments in all seasons, except for summer. More NH3 was lost in summer than in the other seasons, whereas denitrification and N2O losses were highest in winter and lowest in summer. The total annual NH3 loss from the control, ammonium nitrate, and urea treatments averaged 17, 32, and 57 kg N/ha.year, respectively. Annual denitrification losses were estimated at around 6, 15, and 13 kg N/ha.year for the control, ammonium nitrate, and urea treatments, respectively. Total gaseous N losses were estimated to be 23, 47, and 70 kg N/ha.year from the control, ammonium nitrate, and urea treatments respectively.Although the use of ammonium nitrate fertiliser would significantly reduce NH3 volatilisation losses in summer, this fertiliser costs 45% more per unit N than urea, so there is no economic justification for recommending its use over urea for the other seasons. However, the use of urea during the cooler, wetter months may result in significantly less denitrification loss. The results are discussed in terms of potential management strategies to improve fertiliser efficiency and reduce adverse effects on the environment.
Response of two citrus genotypes to six boron concentrations: concentration and distribution of nutrients, total absorption, and nutrient use efficiency
Authors: Papadakis I. E. , Dimassi K. N. , Therios I. N.
Published: August 2004

A greenhouse experiment was performed to study the effects of boron (B) on growth, nutrient concentration and distribution, nutrient use efficiency, and total nutrient absorption of 2 citrus genotypes. The experimental layout was a 6 × 2 factorial, with 6 B concentrations (0.05, 0.25, 0.50, 1.00, 2.00, and 5.00 mg/L) on 2 genotypes: the sour orange (Citrus aurantium L.) and the Swingle citrumelo (C. paradisi Macf. × Poncirus trifoliata L.). The plants were grown for 3 months in a B-free sand : perlite (1 : 1) medium that was irrigated with 6 half-strength Hoagland's nutrient solutions. Increasing B supply in the nutrient solution increased the B concentration linearly in all parts of the plant in the following order: basal leaves > top leaves > bark > root > stems > wood. There was no consistent effect of B supply on the concentration of other fundamental elements (P, K, Ca, Mg, Mn, Zn, Fe). Furthermore, none of the tested B concentrations significantly affected the total plant content and consequently the absorption of any other element. A concentration of 1.00 mg B/L or higher resulted in less B absorption by the Swingle citrumelo than by the sour orange. Furthermore, the Swingle citrumelo has the ability to retain more B in its stems and roots than the sour orange, thus preventing B transport to leaves. Finally, B and Mn use efficiency in both genotypes correlated significantly and negatively with the B supply.
Development of visual tools for selecting qualitative corm characteristics of taro (Colocasia esculenta (L.) Schott)
Authors: Ivancic A. , Garcia J. Quero , Lebot V.
Published: August 2004

Taro (Colocasia esculenta (L.) Schott) is an allogamous and polymorphic species with thousands of cultivars. Tremendous morphological variation can be created by artificial genetic recombination. The breeding of taro is expensive, especially when the breeders have to deal with large populations of 10 000 or more individuals. One of the most efficient ways to improve the breeding efficiency is to start selection in an early stage of development, without uprooting the plants, which usually takes 15 months after the germination of seeds. Such an approach has been considered for determining taro corm flesh and corm fibre colours, as these traits are very important for marketing. In the present study, the phenotypic correlation analysis shows that most of the colours of the corm flesh and corm fibres can be determined by scoring the colour of the petiole base and the colour of the lower part of the petiole (2–3 mm above the base). This can be done in an early stage of development and speeds up the recurrent selection process.
Variation in the chemical composition of wheats grown in Western Australia as influenced by variety, growing region, season, and post-harvest storage
Authors: Kim J. C. , Mullan B. P. , Simmins P. H. , Pluske J. R.
Published: August 2004

Two experiments were conducted to examine varietal and environmental influences on physical characteristics and chemical content in a cohort of wheats grown in Western Australia. In Expt 1, a 3 × 3 × 2 factorial experiment examined the relationships between wheat variety (Arrino, Stiletto, and Westonia), growing region (high, medium, and low rainfall zone), and 2 harvest years (1999 and 2000). In Expt 2, the effect of storage for 6�months on the chemical composition of the wheats was examined. Wide variations in the content of crude protein (CP, CV 19.4%), total starch (CV 5.45%), total non-starch polysaccharides (NSP, CV 9.4%), insoluble NSP (CV 10.4%), and soluble NSP (CV 20.7%) were observed. The crude protein content of wheat was inversely related to total starch content (r = –0.779, P < 0.001). Variety influenced fast digestible starch (P < 0.001), acid detergent fibre (ADF, P < 0.01), total NSP (P < 0.05), insoluble NSP (P < 0.05), and in vitro extract viscosity (P < 0.05). The annual precipitation level (mm) irrespective of growing region was correlated to bushel weight (r = –0.683, P�<�0.01), CP (r = –0.631, P < 0.01), total starch (r = 0.526, P < 0.05), ADF (r = –0.687, P < 0.01), lignin (r�=�–0.863, P < 0.001), soluble NSP (r = 0.826, P < 0.001), and free sugar contents (r = –0.795, P < 0.001), indicating the importance of annual rainfall for accumulation of protein, carbohydrates, and lignin in wheats. Harvest year had a strong influence on chemical composition (P < 0.05 to <0.001) and bushel weight (P < 0.001) of wheat. Storage for 6 months decreased soluble NSP (P < 0.01), ADF (P < 0.05), and lignin content (P < 0.01), and increased free sugar content (P < 0.001).
Effect of climate variability on event frequency of sorghum ergot in Australia
Authors: Wang Enli , Ryley Malcolm , Meinke Holger
Published: August 2004

The significant effect of ergot, caused by Claviceps africana, on the Australian sorghum industry, has led to considerable research on the identification of resistant genotypes and on the climatic conditions that are conducive to ergot outbreaks. Here we show that the potential number of monthly ergot events differs strongly from year to year in accordance with ENSO (El Niño–Southern Oscillation)-related climate variability. The analysis is based on long-term weather records from 50 locations throughout the sorghum-growing areas of Australia and predicts the potential number of monthly ergot events based on phases of the Southern Oscillation Index (SOI). For a given location, we found a significant difference in the number of potential ergot events based on SOI phases in the preceding month, with a consistently positive SOI phase providing the greatest risk for the occurrence of ergot for most months and locations. This analysis provides a relative risk assessment for ergot outbreaks based on location and prevailing climatic conditions, thereby assisting in responsive decision-making to reduce the negative effect of sorghum ergot.
Effect of sodium exclusion trait on chlorophyll retention and growth of durum wheat in saline soil
Authors: Husain Shazia , Munns Rana , Condon A. G. (Tony)
Published: August 2004

Six durum wheat genotypes with contrasting extents of sodium accumulation in leaves were used to assess the effects of sodium exclusion on leaf longevity and biomass production in saline soil. Leaf chlorophyll content, ion concentration, plant height, and dry biomass were measured at 3 salinity levels (1, 75, and 150 mM NaCl, with supplemental Ca2+). Yield and yield components were measured on 2 contrasting groups of genotypes. The low Na+ genotypes showed much longer chlorophyll retention than the high Na+ genotypes, the start of leaf senescence being prolonged by a week or more in the low Na+ genotypes. The difference was greatest at 75 mM NaCl. At ear emergence, the effects of salinity on biomass were less on the low Na+ than on the high Na+ genotypes at 75 mM NaCl, but there was no difference between groups at 150 mM NaCl. At maturity, salinity had a similar effect on biomass of both genotypes, at both 75 and 150 mM NaCl. Grain yield at 150 mM NaCl was equally reduced in both genotypes, being only 12% of controls. However, at 75 mM NaCl there was a signficant yield difference between genotypes; yield of the high Na+ genotype was only 70% of controls, whereas yield of the low Na+ genotype was 88% of controls. The greater yield of the low Na+ genotype was due to enhanced grain number and grain weight in the tiller ears.
Fibre evanescent field absorption (FEFA): an optical fibre technique for measuring light absorption in turbid water samples
Authors: Lamb D. W. , Bunganaen Y. , Louis J. , Woolsey G. A. , Oliver R. , White G.
Published: August 2004

An optical fibre technique for measuring the absorption of water-borne pigment in the present of significant suspended sediment concentration has been evaluated. Based on the absorption of the evanescent field of light propagating down a single glass (silica) fibre, the fibre evanescent field absorption (FEFA) technique has been demonstrated to be approximately 10-fold less sensitive to absorbing species than traditional bulk absorption methods. However, unlike traditional optical absorption measurements, the FEFA technique is insensitive to scattering by the suspended particles for particle concentrations expected in typical inland waters. A simple calculation estimates that this insensitivity persists for sediment concentrations up to 2000-fold those expected in Australian inland rivers. In addition to experimental results, a discussion of the potential operational use of this technique in measuring optical absorption properties of water containing suspended sediment is presented.
Temporal patterns in distributions of tropical fish larvae on the North West Shelf of Australia
Authors: Sampey A. , Meekan M. G. , Carleton J. H. , McKinnon A. D. , McCormick M. I.
Published: August 2004

Information on the temporal distributions of tropical fish larvae is scarce. Early stage larval fishes were sampled using towed bongo plankton nets at sites on the southern North West Shelf of Australia (21°49′S, 114°14′E), between October and February of 1997/98 and 1998/99. The first summer was characterised by El Niño–Southern Oscillation-driven upwelling and high primary productivity, whereas in the second summer water temperatures were warmer and primary production was lower. Benthic percoid shorefishes dominated surface assemblages in both summers and this pattern may be typical of tropical shelf environments.The abundance and diversity of larval fishes were lowest in October and increased from November through to February. Assemblages displayed weak cross-shelf patterns, with a few taxa being more abundant at inshore sites (e.g. monacanthids), whereas others were more abundant offshore (e.g. scombrids). Although the composition of assemblages remained relatively consistent, many taxa (e.g. pomacentrids and carangids) showed differences in abundance between summers. Multivariate analyses found no relationships between abundance patterns of larval fishes and biophysical variables, such as temperature, salinity, and zooplankton biomass. Thus, seasonal changes in abundance may reflect differences in the spawning activities of adult fishes and/or larval survival.
Effect of a temporally heterogeneous environment on size and shape of the giant ostracods Mytilocypris (Ostracoda : Cyprididae) from Australian salt lakes
Authors: Finston Terrie L.
Published: August 2004

The giant ostracods Mytilocypris occupy temporary saline habitats in Australia and experience physical and chemical heterogeneity in association with evaporation. Three sympatric species, namely M. mytiloides, M. tasmanica chapmani, and M. minuta, show high genetic similarity and morphological boundaries that overlap. The large elongate, intermediate, and small blunt shells of the three species are associated with lakes of low, intermediate, and high salinity, respectively. The present study investigated whether all three phenotypes were produced through time in single habitats experiencing seasonal changes in physical and chemical properties. Three lakes at one site (Coorow) were temporally heterogeneous, showing a nearly 10-fold increase in salinity in a single season, whereas four lakes at a second site (Rottnest Island) were more or less permanent and showed less environmental variation. Successive generations in the lakes from Coorow became smaller and blunter in association with environmental changes, showing the range of phenotypes displayed in the three presumptive taxa. There was less phenotypic response in individuals from Rottnest Island, reflecting the relative homogeneity of the lakes. Possible mechanisms underlying the observed changes include phenotypic plasticity, genotype replacement, and strong selection.
Comparisons of assemblages of phytoplankton between open water and seagrass habitats in a shallow coastal lagoon
Authors: Cummins S. P. , Roberts D. E. , Ajani P. , Underwood A. J.
Published: August 2004

Patterns of phytoplankton in areas with seagrass (Zostera capricorni, Halophila ovalis, and Ruppia megacarpa) and areas without seagrass were quantified in an estuary near Sydney, NSW, Australia. Replicate samples (separated by metres) were collected on 20 randomly chosen occasions over almost 3 years, from two sites (separated by tens of metres) nested in both habitats, at four locations (separated by kilometres). Areas with seagrass often supported a significantly different assemblage of phytoplankton compared with areas without seagrass. Dissimilarities were due to small differences in the relative abundance of taxa, particularly the diatom Pseudonitzschia cf. pseudodelicatissima, rather than the presence or absence of specific taxa. In both habitats, abundances of phytoplankton were patchy at all of the spatial scales sampled, although most of the variation was among replicate samples. These findings emphasise the need to incorporate a hierarchy of scales in programs designed to understand processes that cause spatial and temporal patterns of phytoplankton or to detect changes in response to human activities.