bluuebunny/crossref_metadata_2025 huggingface dataset:
Microwave and ab initio studies of the Xe–CH4 van der Waals complex
Authors: Wen Qing , Jäger Wolfgang
Published: December 2005

An ab initio potential-energy surface of the Xe–CH4 van der Waals complex was constructed at the coupled cluster level of theory with single, double, and perturbatively included triple excitations. The recently developed small-core pseudopotential and augmented correlation-consistent polarized valence quadruple-zeta basis set was used for the xenon atom and Dunning’s augmented correlation-consistent polarized valence triple-zeta basis set for the other atoms. The basis sets were supplemented with bond functions. Dipole moments were also calculated at various configurations. Rotational spectra of the Xe–CH4 van der Waals complex were recorded using a pulsed-nozzle Fourier transform microwave spectrometer. The isotopomers studied include those of CH4,CH134,CD4,CH3D, and CHD3 with the five most abundant Xe isotopes. Transitions within three internal rotor states, namely, the j=0,K=0;j=1,K=0; and j=2,K=1 states, were observed and assigned. Nuclear quadrupole hyperfine structures due to the presence of Xe131(I=3∕2) were detected and analyzed. It was found that the j=1,K=0 state is perturbed by a Coriolis interaction with a nearby j=1,K=1 state. For isotopomers containing CH3D and CHD3, the j=2 states are no longer metastable and could not be observed. The spectroscopic results were used to derive structural and dynamical information of the Xe–CH4 complex.
The boundary fluctuation theory of transport coefficients in the linear-response limit
Authors: Petravic Janka , Harrowell Peter
Published: December 2005

In this paper we present, for the first time, a linear-response theory of transport coefficients—shear viscosity and thermal conductivity—involving thermal, as opposed to mechanical, fields. The theory involves the explicit treatment of the boundaries and the constraints that are applied to them. Expressions for the shear viscosity and thermal conductivity are obtained in terms of the fluctuations at the boundaries of the variable conjugate to that which is constrained. We explain how the choice of ensemble, as defined by the boundary constraints, determines the form in which the transport coefficients are evaluated.
Thermal relaxation mechanism and role of chemical functionalization in fullerene solutions
Authors: Shenogin Sergei , Keblinski Pawel , Bedrov Dmitry , Smith Grant D.
Published: December 2005

Using molecular-dynamics simulations we investigate thermal relaxation of C60 and C84 molecules suspended in octane liquid. Pristine fullerenes exhibit relatively slow relaxation due to weak thermal coupling with the liquid. A comparison of the interfacial transport characteristics obtained from relaxation simulations with those obtained from equilibrium simulations and fluctuation-dissipation theorem analysis demonstrates that the relaxation process involves two main steps: (i) energy flow from high- to low-frequency modes within the fullerene, and (ii) energy flow from low-frequency fullerene modes to the liquid. Functionalization of fullerenes with alkene chains leads to significant reduction of the thermal relaxation time. The relaxation time of functionalized fullerenes becomes independent from the functionalizing chain length beyond ∼10 carbon segments; this can be understood in terms of thermal conductivity along the chain and heat transfer between the chain and the solvent.
Assembly and infection process of bacteriophage T4
Authors: Arisaka Fumio
Published: December 2005

Bacterophage T4 consists of three parts, namely, a head, a tail, and six tail fibers, each of which is assembled along an independent pathway and then joined. In contrast to simple plant viruses such as tobacco mosaic virus, disassembly and reassembly of the virion is not possible. This is due mainly to the fact that the assembly involves not only irreversible steps such as cleavage of covalent bonds of some constituent proteins, but also that it requires a scaffold and involves the inner membrane of the host cell. Another unique feature of the assembly as a biological nanomachine is the involvement of specific protein devices such as a “ruler molecule,” which determines the length of the tail, an ATP-driven DNA packaging protein complex, and phage-encoded molecular chaperones. Recent structural biological studies of the phage started to unveil the molecular mechanics of structural transformation of the tail upon infection.
Dielectric breakdown mechanisms in gate oxides
Authors: Lombardo Salvatore , Stathis James H. , Linder Barry P. , Pey Kin Leong , Palumbo Felix , Tung Chih Hang
Published: December 2005

In this paper we review the subject of oxide breakdown (BD), focusing our attention on the case of the gate dielectrics of interest for current Si microelectronics, i.e., Si oxides or oxynitrides of thickness ranging from some tens of nanometers down to about 1nm. The first part of the paper is devoted to a concise description of the subject concerning the kinetics of oxide degradation under high-voltage stress and the statistics of the time to BD. It is shown that, according to the present understanding, the BD event is due to a buildup in the oxide bulk of defects produced by the stress at high voltage. Defect concentration increases up to a critical value corresponding to the onset of one percolation path joining the gate and substrate across the oxide. This triggers the BD, which is therefore believed to be an intrinsic effect, not due to preexisting, extrinsic defects or processing errors. We next focus our attention on experimental studies concerning the kinetics of the final event of BD, during which the gate leakage increases above acceptable levels. In conditions of intrinsic BD, the leakage increase is due to the growth of damage within the oxide in localized regions. Observations concerning this damage are reviewed and discussed. The measurement of the current, voltage, and power dissipated during the BD transient are also reported and discussed in comparison with the data of structural damage. We then describe the current understanding concerning the dependence of the BD current transient on the conditions of electric field and voltage. In particular, as the oxide thickness and, as a consequence, the voltage levels used for accelerated reliability tests have decreased, the BD transient exhibits a marked change in behavior. As the stress voltage is decreased below a threshold value, the BD transient becomes slower. This recently discovered phenomenon has been termed progressive BD, i.e., a gradual growth of the BD spot and of the gate leakage, with a time scale that under operation conditions can be a large fraction of the total time to BD. We review the literature on this phenomenon, describing the current understanding concerning the dependence of the effect on voltage, temperature, oxide thickness, sample geometry, and its physical structure. We also discuss the possible relation to the so-called soft oxide BD mode and propose a simpler, more consistent terminology to describe different BD regimes. The last part of the paper is dedicated to exploratory studies, still at the early stages given the very recent subject, concerning the impact on the BD of materials for the metal-oxide-semiconductor gate stack and, in particular, metal gates.
Intrinsic behavior of face-centered-cubic supra-crystals of nanocrystals self-organized on mesoscopic scale
Authors: Pileni M. P.
Published: December 2005

We describe intrinsic behavior due to the high ordering of nanocrystals at the mesoscopic scale. The first example shows well-defined columns in the formation of cobalt nanocrystals when an applied magnetic field is applied during the evaporation process. Collective breathing properties between nanocrystals are demonstrated. In both cases, these features are observed when the nanocrystals are highly ordered in fcc supra-crystals.
Electronic electrooptic phase modulation using bent-core liquid crystals
Authors: Rickard Malcolm , Nakata Michi , Takezoe Hideo , Watanabe Junji , Clark Noel A.
Published: December 2005

The electronic contribution to the second-order nonlinear polarizability of a ferroelectric liquid-crystal phase formed by the spontaneously polar organization of bent-core molecules has been demonstrated. Application of a 40MHz driving voltage and measurement of the refractive index modulation of light of wavelength 1.3μm yields electrooptic coefficients r∼10pm∕V, comparable to that found in poled polymers.
Optimization of tapered semiconductor optical amplifiers for picosecond pulse amplification
Authors: Gehrig E. , Hess O.
Published: December 2005

We present results of a fundamental device simulation study aimed at an optimization of high-power tapered semiconductor optical amplifiers for picosecond pulse amplification. Thereby, the microscopic light-matter coupling is described on the basis of a spatially resolved Maxwell–Bloch–Langevin description that takes into account many-body-carrier interactions, energy transfer between the carrier and phonon systems and, in particular, the spatiotemporal interplay of stimulated and amplified spontaneous emission and the noise caused by spontaneous emission. Extensive simulation runs reveal the microscopic physical processes which are responsible for the beam quality of the amplified picosecond pulses and allow us to give concrete suggestions for the optimization of the amplifier structure and geometry. We discuss the influence of a curved waveguide or spatially patterned current contact, and identify the length of the unpumped area as the most critical parameter to be carefully optimized.
Polymer hot-carrier transistor
Authors: Chao Yu-Chiang , Yang Syuan-Ling , Meng Hsin-Fei , Horng Sheng-Fu
Published: December 2005

Metal-base hot-carrier transistor with conjugated polymer emitter and collector is demonstrated. The device is fabricated by multiple spin coating with the metal base sandwiched between two polymers. A thin insulating layer of LiF is inserted between the emitter and base to enhance the hot carrier kinetic energy and reduce mutual dissolution. Using poly(9-vinylcarbazole) as the emitter, Al as the base, and poly(3-hexylthiophene) as the collector, common-emitter current gain of 25 is obtained with operation voltage as low as 5 V.
Spontaneous and piezoelectric polarization effects in wurtzite ZnO∕MgZnO quantum well lasers
Authors: Park Seoung-Hwan , Ahn Doyeol
Published: December 2005

Spontaneous and piezoelectric polarization effects on electronic and optical properties of ZnO∕MgZnO quantum well (QW) structures are investigated by using the non-Markovian gain model with many-body effects. The spontaneous polarization constant for MgO determined from a comparison with the experiment is about −0.070C∕m2, which is larger than the value (−0.050C∕m2) for ZnO. The negligible internal field effect observed in the case of ZnO∕MgZnO QW structures with relatively low Mg composition (x<0.2) and thin well width (Lw<46Å) can be explained by the cancelation of the sum of piezoelectric and spontaneous polarizations between the well and the barrier. The ZnO∕MgZnO QW laser has much larger optical gain than the GaN∕AlGaN QW laser. This is attributed to the fact that the ZnO∕MgZnO QW structure has a larger optical matrix element due to the relatively small internal field, compared to the GaN∕AlGaN QW structure.
Effects of heavy boron doping on the valence band offset at the Si1−xGex∕Si interface and Si1−xGex band gap
Authors: Liu Jing , Ozturk Mehmet C.
Published: December 2005

Heavily boron-doped Si1−xGex alloys are currently used in recessed source/drain regions of nanoscale metal oxide silicon field effect transistors. Small boron atoms can partially compensate the Si1−xGex strain and change its band gap, which can influence key device parameters such as the junction contact resistance. In this work, the depletion region capacitance of SiGe∕Si heterojunction diodes was measured to determine the valence band offset and the Si1−xGex band gap. The results show that boron doping can have a significant impact on the Si1−xGex band gap and values between those of relaxed and fully strained Si1−xGex alloys can be obtained.
Enzyme-immobilized SiO2–Si electrode: Fast interfacial electron transfer with preserved enzymatic activity
Authors: Wang Gang , Yau Siu-Tung
Published: December 2005

The enzyme, glucose oxidase (GOx), is immobilized using electrostatic interaction on the native oxide of heavily doped n-type silicon. Voltammetric measurement shows that the immobilized GOx gives rise to a very fast enzyme-silicon interfacial electron transfer rate constant of 7.9s−1. The measurement also suggests that the enzyme retains its native conformation when immobilized on the silicon surface. The preserved native conformation of GOx is further confirmed by testing the enzymatic activity of the immobilized GOx using glucose. The GOx-immobilized silicon is shown to behave as a glucose sensor that detects glucose with concentrations as low as 50μM.
Electron acceleration by a chirped short intense laser pulse in vacuum
Authors: Singh K. P.
Published: December 2005

Electron acceleration by a chirped short intense laser pulse has been studied in a vacuum. A linear frequency chirp ω(t)=ω0(1−αt) has been considered, where ω0 is the laser frequency at z=0 and α is frequency chirp parameter. Transverse electron momentum increases due to frequency chirp and the electron escapes from the laser pulse near the pulse peak. Longitudinal momentum also increases due to increase in longitudinal force. Retained electron energy is much higher with frequency chirp than that without frequency chirp. Retained energy peaks for a suitable value of α; the value of which decreases with laser intensity and initial electron energy.
Light emission from an ambipolar semiconducting polymer field-effect transistor
Authors: Swensen James S. , Soci Cesare , Heeger Alan J.
Published: December 2005

Ambipolar light-emitting field-effect transistors are fabricated with two different metals for the top-contact source and drain electrodes; a low-work-function metal defining the channel for the source electrode and a high-work-function metal defining the channel for the drain electrode. A thin film of polypropylene-co-1-butene on SiNx is used as the gate dielectric on an n++-Si wafer, which functioned as the substrate and the gate electrode. Transport data show ambipolar behavior. Recombination of electrons and holes results in a narrow zone of light emission within the channel. The location of the emission zone is controlled by the gate bias.
Carbon nanotube Schottky diode and directionally dependent field-effect transistor using asymmetrical contacts
Authors: Yang M. H. , Teo K. B. K. , Milne W. I. , Hasko D. G.
Published: December 2005

We demonstrate the fabrication and operation of a carbon nanotube (CNT) based Schottky diode by using a Pd contact (high-work-function metal) and an Al contact (low-work-function metal) at the two ends of a single-wall CNT. We show that it is possible to tune the rectification current-voltage (I-V) characteristics of the CNT through the use of a back gate. In contrast to standard back gate field-effect transistors (FET) using same-metal source drain contacts, the asymmetrically contacted CNT operates as a directionally dependent CNT FET when gated. While measuring at source-drain reverse bias, the device displays semiconducting characteristics whereas at forward bias, the device is nonsemiconducting.
Phase stability, oxygen nonstoichiometry and magnetic properties of BiFeO3−δ
Authors: Li Meicheng , MacManus-Driscoll Judith L.
Published: December 2005

The phase stability of polycrystalline BiFeO3−δ (BFO) was measured using coulometric titration in the technologically important temperature range for growth of epitaxial thin films, 680°C–800°C. BFO exhibits only a very narrow oxygen nonstoichiometry, i.e., δ<0.01. For the most nonstoichiometric sample obtainable at 800°C (containing a maximum Fe2+ fraction of 2mol%) the saturation magnetization was 3.1×10−4μB∕Fe, a factor of around 2 higher than a nominally fully oxygenated sample. Hence, the contribution of Fe2+ to the ferromagnetism is small. The decomposition products of BFO below the oxygen phase stability line are Bi25FeO40−x and γ-Fe2O3.
Electronic structure of calcium hexaborides
Authors: Lee Byounghak , Wang Lin-Wang
Published: December 2005

We present a theoretical study of crystal and electronic structures of CaB6 within a screened-exchange local density approximation (sX-LDA). Our ab initio total energy calculations show that CaB6 is a semiconductor with a gap of >1.2eV, in agreement with recent experimental observations. We show a very sensitive band-gap dependence on the crystal internal parameter, which might partially explain the scatter of previous theoretical results. Our calculation demonstrates that it is essential to study this system simultaneously for both crystal structures and electronic properties, and that the sX-LDA provides an ideal method for this problem.
Broadband omnidirectional reflection from negative index materials
Authors: Bloemer Mark , D’Aguanno Giuseppe , Scalora Michael , Mattiucci Nadia
Published: December 2005

We show, by using a dispersion relation with parameters taken from experimental data, that a single layer of a negative index material has omnidirectional reflection properties. In the range between the electric plasma frequency and the magnetic plasma frequency, the refractive index is close to zero and the negative index materials reflect radiation for all angles of incidence and polarization with reflectivities of ∼99%. In addition, with increasing angles of incidence, the reflecting band does not shift in frequency but actually widens. The operational bandwidth can be 100% or greater by increasing the separation between the electric and magnetic plasma frequencies.
Carbon nanotube effects on electroluminescence and photovoltaic response in conjugated polymers
Authors: Xu Zhihua , Wu Yue , Hu Bin , Ivanov Ilia N. , Geohegan David B.
Published: December 2005

This letter reports the experimental results of enhanced electroluminescence (EL) and photovoltaic (PV) response upon doping single-wall carbon nanotubes (SWNTs) into conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-1, 4-phenylenevinylene] (MEHPPV) based on single-layer light-emitting diodes. We found that the dispersed SWNTs result in two processes: charge transport and exciton dissociation at the tube-chain interface in the SWNT/polymer composites. The detailed EL and PV studies indicate that low SWNT doping concentrations mainly improve the bipolar charge injection, leading to enhanced both reverse and forward EL with reduced threshold voltage. As the SWNT doping concentration continues to increase, the interfacial exciton dissociation becomes dominated, giving rise to an increased PV response. This SWNT concentration-dependent charge transport and exciton dissociation present a pathway to individually address the dual EL and PV functionalities of SWNT-doped polymer composites by controlling the doping level of the SWNTs.
Blueshift of surface plasmon resonance spectra in anneal-treated silver nanoslit arrays
Authors: Jung Yun Suk , Sun Zhijun , Kim Hong Koo , Blachere Jean
Published: December 2005

Silver nanoslit arrays were anneal treated in vacuum, and the effects on the surface morphology of silver and the surface plasmon resonance characteristics were investigated. Optical transmission through nanoslit arrays shows a distinctive change in the spectral profiles after annealing: A clear blueshift of the transmission peaks and dips (20nm shift for an anneal temperature of 150°C). Scanning electron microscopy reveals a morphological change of silver: Increased grain sizes, and smooth and round surface profiles after the anneal treatment. The observed blueshift of transmission spectra correlates well with the geometrical and dimensional changes of silver islands defined between slits, which are found to alter the surface plasmon resonance conditions involving various mechanisms in different regimes.
Electrical conductivity of a single C60 nanotube
Authors: Xing Y. J. , Jing G. Y. , Xu J. , Yu D. P. , Liu H. B. , Li Y. L.
Published: December 2005

Electrical conductivity measurements were carried out on a single C60 nanotube fabricated via template growth technique. High resistance was observed from untreated C60 nanotubes. The I-V characteristics of the annealed C60 nanotubes indicate that a Schottky barrier exists between the electrode and the nanotube, which can be modified via annealing in vacuum. The activation energy of the annealed samples is close to the value of single C60 crystal. It was found that the C60 nanotube shows a large photoconductivity under light illumination and is an excellent candidate for optical switch. Our results suggest that the semiconducting C60 nanotube can be used as a rational building block in the construction of hierarchical architectures.
Inelastic mean-free path of electrons at nanocrystalline diamond surfaces
Authors: Zemek J. , Potmesil J. , Vanecek M. , Lesiak B. , Jablonski A.
Published: December 2005

Surprisingly large difference between inelastic mean-free path (IMFP) values of signal electrons calculated from optical data and from the predictive TPP-2M formulae for diamond or graphite has motivated us to verify both sources of IMFP by measuring these values using different method. Thin, perfectly transparent nanocrystalline diamond films were characterized by x-ray induced photoelectron and Auger electron spectroscopy. Elastic peak electron spectroscopy measurements and the Monte Carlo calculations of electron transport were applied to determine the IMFPs for medium electron energy. The surface energy losses were also considered when evaluating these IMFPs.
Effect of reproductive status, body condition and age of Bos indicus cross cows early in a drought on survival and subsequent reproductive performance
Authors: Fordyce G , Tyler R , Anderson VJ
Published: December 2005

A herd of 802 Brahman cross cows, managed under extensive conditions (7000 ha paddock with twice-yearly handling) in a dry tropical environment, was studied during the severe drought of 1982-83. Twenty-one per cent of the cows died. Cows more advanced in pregnancy and those in poorer condition in the early stages of the drought had lower (P<0.05) survival probabilities. Cows aged over 7 years also generally had a reduced (P<0.05) probability of survival. Calf loss between confirmed pregnancy early in the drought and weaning after the following wet season was 31%. Calf loss from surviving cows was not higher than is usual in non-drought years. All deaths of lactating cows were associated with calf deaths. The practical use of these results in cost-efficient management for survival of cows in drought was then evaluated in a second study in which 293 cows were drafted into high- and low-supplement-requirement (HSR and LSR) groups in the early stages of the 1987 drought. Survival feeding in the HSR group commenced about 6 weeks earlier than would have been necessary in the LSR group. In both studies, reproductive status in the early drought period was a significant determinant of both body condition and conception rates early in the following year. Cows more advanced in pregnancy early in the drought were in poorer condition after the following wet season (P<0.05), but remained further advanced in pregnancy (P<0.05). Both body condition in the early part of the drought and age had minimal effects on performance in the following wet season, although younger cows tended to be lighter and have the lowest conception rates. Cows in better condition after the wet season had higher (P<0.05) pregnancy rates.
Growth and carcass characteristics of male crossbred lambs from high fecundity Booroola x Polwarth ewes: effects of litter size, castration and age
Authors: Ritar AJ , Williams PM , O'May PJ , Gilbert KD , Bond EM , King CF
Published: December 2005

Growth and carcass characteristics were obtained for 154 Border Leicester-sired male lambs, from highly fecund Booroola x Polwarth ewes, grazed on improved Tasmanian pasture and either left entire or castrated, followed by slaughter at 134, 192 or 288 days of age. Of all lambs, 15.6% were single born and 84.4% were multiple born (54.5% twins, 19.5% triplets, 8.4% quadruplets and 1.9% quintuplets). Multiples were lighter than singles at birth (3.6 v. 4.4 kg), at weaning at 78 days (21.0 v. 25.8 kg), and before slaughter at 134 days (27.5 v. 31.1 kg), 192 days (33.9 v. 36.1 kg) and 288 days (37.5 v. 42.5 kg). Similarly, carcasses were lighter and leaner, and dressing percentages were lower for multiples than for singles, but when carcass weight was included as the covariate in further analysis of carcass characteristics, there was no effect of birth type. There were no significant interactions between birth type and castration. The growth rate of ram lambs became progressively faster than wethers from weaning onwards. Liveweight differences could be detected from 134 days of age (28.8 v. 27.2 kg), but ram lamb carcasses were not heavier until 288 days (18.1 v. 16.0 kg). At 192 days, rams were leaner than wethers (condition score, 2.2 v. 2.5; GR tissue depth, 8.5 v. 11.5 mm; C-site fat depth, 3.7 v. 5.1 mm), and rams had lower dressing percentages (41.8 v. 44.0%) and larger eye muscle areas (1097 v. 1010 mm2), but carcass weights were similar (14.8 v. 14.6 kg). We conclude that the only effect of multiple birth was to delay maturation and development of lambs to reach the suitable market weight. Leaving males entire did not improve carcass weights until 288 days, which is of little benefit to Tasmanian producers where lambs are normally sold at a much younger age.
Marginal deficiencies of cobalt and selenium in weaner sheep: response to supplementation
Authors: Masters DG , Peter DW
Published: December 2005

Five groups of 30 weaner wethers were given (i) no treatment, or a supplement of either (ii) copper (injection), (iii) cobalt (intraruminal pellet), (iv) selenium (intraruminal pellet) or (v) copper, cobalt plus selenium (intraruminal, soluble glass bolus). Liveweight, wool growth and indicators of copper, cobalt and selenium status were measured over a 54-week experimental period. The provision of all 3 elements resulted in a 180 g increase (P<0.05) in clean wool growth relative to controls. With selenium or cobalt alone there was a trend towards increases in clean wool, whereas wool growth of copper treated sheep was identical to the controls. There were no persistent or significant treatment effects on liveweight. The results indicate that both wool and liveweight changes should be used to assess responses to trace elements and show that combined deficiencies, not detectable in experiments using single element supplements, may depress productivity in grazing sheep. Glass boluses were an effective method of providing selenium and raised selenium in liver and plasma for 54 weeks. Selenium pellets resulted in smaller, less persistent increases in these tissues. Glass boluses were less effective than cobalt pellets in providing cobalt and resulted in only a small increase in vitamin B12 at 26 weeks (P=0.1), compared with increases due to cobalt pellets at both 26 and 54 weeks (P<0.05).
Aphanomyces euteiches, a possible cause of poor lucerne establishment in the Lockyer Valley, Queensland
Authors: Abbo EO , Irwin JAG
Published: December 2005

Aphanomyces euteiches isolates were were recovered from Lockyer Valley, Queensland soils using pea and lucerne as baits. The isolates showed high levels of virulence on both pea and lucerne, and were mildly virulent on bean and chickpea. A range of disease reactions were observed when lucerne cultivars inoculated with A. euteiches. CUF-101 was the most resistant line, and cvv. Hunter River and Trifecta were the most susceptible. Further work is warranted to determine the role of A. euteiches as a factor in the poor establishment of Phytoplithora root rot resistant lucerne cultivars in Queensland.
Comparison of yield, cob characteristics and sensory quality of six supersweet (sh2) corn cultivars grown in a subtropical environment
Authors: Olsen JK , Blight GW , Gillespie D
Published: December 2005

Yield and cob characteristics of 6 supersweet corn (Zea mays L.) cultivars, homozygous for the recessive shrunken-2 (sh2) allele, were compared at 3 separate planting dates, in 1987-88, at Bundaberg (lat. 25�S.), Queensland. Sensory quality of the 6 sh2 cultivars and a standard cultivar, homozygous for the recessive sugary (su) allele, were compared in a separate experiment. Marketable yield (total weight of cobs-in-husks with at least 125 mm usable kernels without damage or defects) declined between each of the plantings: midwinter, early spring, late spring. Marketable yield of the cultivar Sucro was consistently high (9.18-13.7 t/ha), whereas, that of Honey Sweet was low (2.88-5.43 t/ha). Total weight of unmarketable cobs (cobs-in-husks with 125 mm usable kernels or cobs-in-husks having at least 125 mm usable kernels, but with damage or defects) was highest for Honey Sweet and ranged between 5.31 and 9.18 t/ha. Marketable yields of the 6 sh2 cultivars were similar to those obtained in other warm climates but were lower than those in cooler climates. The cobs-in-husks of Honey Sweet and Sucro from the midwinter planting were marginally heavier than the preferred cob-in-husk range (310-360 g/cob) demanded on domestic markets; those of Snosweet, Candy Sweet and Florida Staysweet were within the range; and those of Sugar Sweet were significantly (P<0.05) lower. None of the cultivars at the 2 later sowing dates achieved this desirable weight range. Because of the higher yields and larger cobs produced in the midwinter planting, and the higher incidence of disease and heat stress encountered in the later plantings, it is proposed that sh2 cultivar production should be limited to a midwinter sowing in subtropical Bundaberg. Taste panel testing indicated preference for all sh2 cultivars over the standard su cultivar in terms of both general acceptability and texture (P<0.05), and the su cultivar was rated least sweet (P<0.05). Snosweet was rated highest in terms of both general acceptability and texture scores and was also rated the sweetest cultivar.
Control of Phytophthora canker with phosphonate in artificially inoculated almond and cherry trees
Authors: Wicks TJ , Hall B
Published: December 2005

Phosphonate (H3P03; as FOLI-R-FOS 200) applied as either a soil drench, foliar spray or trunk injection before infection inhibited the development of cankers in almond and cherry trees inoculated with Phytophthora cambivora. Phosphonate applied to the foliage in autumn and spring at rates up to 2 g a.i./L was the most effective treatment. Soil drenches up to 10 g a.i./L were also effective, particularly on young trees. Trunk injections completely inhibited the development of P. cambivora in many cases, but due to a possible phytotoxic reaction, the treatment was most suited for mature trees. Foliar sprays of phosphonate are likely to be most practical treatment as these could be applied with other foliar treatments. The inhibitory effect of phosphonate on canker growth persisted for at least 48 weeks after treatment, irrespective of the method of application.
Management of highly fecund ewe types and their lambs for 8-monthly lambing. 1. Effect of lamb weaning age on ewe reproductive activity in spring
Authors: Fogarty NM , Hall DG , Dawe ST , Atkinson W , Allan C
Published: December 2005

The spring reproductive activity of ewes following a late winter lambing, and varying duration of suckling or lamb weaning age of 6-13 weeks, was investigated in 321 Booroola Merino x Dorset (BD) and 543 Trangie Fertility Merino x Dorset (TD) ewe records over 2 years and 238 Border Leicester x Merino (BLM) ewes in the second year. The ewes were joined about 12 weeks post-partum in November for 6 weeks, following lambing in July-August to conform to an %-monthly lambing regime. In the first year, ewes were run with vasectomised rams and oestrus, ovulation rate, and interval to first observed oestrus were determined under a simulated joining regime. In the second year entire rams were joined in spring following July-August lambing and oestrus, pregnancy, fetal number, lambs born per ewe joined and lambing interval were analysed. Amongst ewes rearing lambs, longer suckling significantly increased the interval to first oestrus and the lambing interval (P<0.01), but had no effect on the percentage of ewes expressing oestrus, percentage of pregnant ewes or lambs born. Significantly fewer ewes that lambed but failed to rear any lambs (LL), than ewes rearing lambs expressed oestrus, ovulated and became pregnant. This resulted in considerably lower lambing rates for LL ewes (95.8 v 137.2% lambs born, P<0.01). Reproductive activity was not greatly affected by ewe liveweight or liveweight gain during joining. BD and TD ewes had hgher pregnancy and lambing rates and a shorter lambing interval than BLM ewes. Ovulation rate and fetal number increased with the number of lambs being reared (0.20 � 0.08 and 0.11 � 0.04 per lamb, P<0.05). The results show that high pregnancy and lambing rates can be achieved from natural joining in the spring following late winter lambings within an 8-monthly lambing regime, when lambs are weaned prior to joining.
Reduction of hardseededness in mungbean by short duration high temperature treatment
Authors: Imrie BC
Published: December 2005

Seeds of 2 lines of mungbean (Vigna radiata), soft-seeded cv. Berken and HS23 with 34% hard seeds, were agitated on a hot plate to determine the effects of temperatures up to 200�C on hardseededness, germination and seed variability. The results of this experiment, combined with a pilot trial using a heated rotating cylinder, showed that the temperature of 175�C for 30 s was the optimum treatment to produce seeds suitable for sprouting. This heat treatment reduced hardseededness from 34 to 1%, increased germination from 64 to 96%, and did not increase the percentage of dead seeds.
Measurement of soil matric potential under 'Williams' Bon Cretien' pear comparing regulated deficit with normal irrigation
Authors: Goodwin I , Mitchell PD , Jerie PH
Published: December 2005

Soil matric potential (SMP) was measured under close planted 'William Bon Cretian' pear (Pyrus communis L.) after a period of withholding irrigation and during a period of regulated deficit irrigation (RDI). Trees were trickle irrigated with 20% replacement of pan evaporation over the planting square (Eps) after an initial period without irrigation, and compared with trees constantly irrigated at 80% Eps. Midway between 2 pairs of trees in each treatment (henceforth the 20% and 80% trees), gypsum blocks were installed in a grid pattern at depths of 10, 25, and 40 cm in the tree line and at 30 and 60 cm on the west and east sides of the tree line, to measure soil matric potential (SMP). The blocks were measured prior to, and 12 h, after irrigation. Consistent with previous results under RDI, shoot growth decreased and yields increased on the 20% relative to the 80% trees. Measured SMPs thus represent suitable levels for RDI. After withholding irrigation, SMPs at the 10 and 25 cm depths ranged between -1.25 and -2.61 MPa in the central position, but were less negative away from the tree line (-0.4 to -2.08) and at the 40 cm depth (-0.35 to -0.91). When averaged over all measurement dates during RDI, pre- and post-irrigation SMPs were more negative at all sites under the 20% compared with the 80% treatments. The pattern of wetting under the 20% treatment was restricted to the central tree line, with some skewing towards the east. Within this soil volume SMP fluctuated between irrigations, and prior to irrigation ranged between -0.3 and -0.7 MPa. As it was likely that only a small fraction of the available subsoil moisture was utilised, available water under the 20% treatment probably was confined to this small volume of soil.
Control of pudding spot in Crofton apple
Authors: Jones KM , Bound SA , Oakford MJ , Koen TB
Published: December 2005

Regularly cropped Crofton apple trees in southern Tasmania were thinned using sprays of naphthalene acetic acid (NAA) at 10 mg/L or ethephon at 200 mg/L at balloon blossom (BB), full bloom (FB), 10 days after full bloom (DAFB) or 20 DAFB. These treatments were compared with hand thinning and an unthinned control. Ethephon had a uniformly mild thinning effect (about 30% compared to control), except at 10 DAFB, where no thinning occurred. NAA was inconsistent, thinning well at BB (50%), overthinning at both FB (85%) and 10 DAFB (88%), and underthinning at 20 DAFB (similar to the control). Ethephon applied at BB and FB increased both mean fruit weight (12 and 22%) and fruit size (28 and 79%), but later applications did not. NAA applications generally resulted in increased mean fruit weight and size, except for the 20 DAFB treatment, which was similar to the control. All ethephon treatments had a low incidence (43%) of pudding spot similar to the controls and hand-thinned treatments. Most NAA treatments showed significantly higher levels of pudding spot than the other treatments. It is concluded that ethephon is a more predictable thinner for Crofton than NAA, and its use to control pudding spot is recommended.
Optimisation of storage conditions for 'UC 157' asparagus
Authors: Klieber A , Wills RBH
Published: December 2005

Asparagus (Asparagus officinalis L. cv. UC 157) was harvested in 3 seasons over 3 months and held at various temperatures, controlled atmospheres and relative humidities, and in dips, to optimise storage conditions. The optimum storage temperature was l.5�C, and precooling needed to be applied with the shortest possible delay after harvest. However, asparagus became more sensitive to chilling and lost 3 of 4 weeks of storage life and 2 of 5 days of shelf life at 20�C as the season progressed. Increasing the relative humidity from recommended 94 to 100% reduced weight loss but not quality, and wetting of spears during cooling did not reduce quality provided butt rots were controlled by dipping asparagus butts in saturated calcium hypochlorite. Continuous storage of spears with their butt in aqueous solutions reduced quality due to rotting, splitting and bending, but controlled atmospheres of 8-15% CO2/18-19% O2 extended storage life at l.5�C by 1 week and shelf life at 20�C by 2 days.
Morphological affinities of the
Sahelanthropus tchadensis
(Late Miocene hominid from Chad) cranium
Authors: Guy Franck , Lieberman Daniel E. , Pilbeam David , de León Marcia Ponce , Likius Andossa , Mackaye Hassane T. , Vignaud Patrick , Zollikofer Christoph , Brunet Michel
Published: December 2005

The recent reconstruction of the
Sahelanthropus tchadensis
cranium (TM 266-01-60-1) provides an opportunity to examine in detail differences in cranial shape between this earliest-known hominid, African apes, and other hominid taxa. Here we compare the reconstruction of TM 266-01-60-1 with crania of African apes, humans, and several Pliocene hominids. The results not only confirm that TM 266-01-60-1 is a hominid but also reveal a unique mosaic of characters. The TM 266-01-60-1 reconstruction shares many primitive features with chimpanzees but overall is most similar to
Australopithecus
, particularly in the basicranium. However, TM 266-01-60-1 is distinctive in having the combination of a short subnasal region associated with a vertical upper face that projects substantially in front of the neurocranium. Further research is needed to determine the evolutionary relationships between
Sahelanthropus
and the known Miocene and Pliocene hominids.
Experimental support for the “E pathway hypothesis” of coupled transmembrane e
–
and H
+
transfer in dihemic quinol:fumarate reductase
Authors: Lancaster C. Roy D. , Sauer Ursula S. , Groß Roland , Haas Alexander H. , Graf Jürgen , Schwalbe Harald , Mäntele Werner , Simon Jörg , Madej M. Gregor
Published: December 2005

Reconciliation of apparently contradictory experimental results obtained on the quinol:fumarate reductase, a diheme-containing respiratory membrane protein complex from
Wolinella succinogenes
, was previously obtained by the proposal of the so-called “E pathway hypothesis.” According to this hypothesis, transmembrane electron transfer via the heme groups is strictly coupled to cotransfer of protons via a transiently established pathway thought to contain the side chain of residue Glu-C180 as the most prominent component. Here we demonstrate that, after replacement of Glu-C180 with Gln or Ile by site-directed mutagenesis, the resulting mutants are unable to grow on fumarate, and the membrane-bound variant enzymes lack quinol oxidation activity. Upon solubilization, however, the purified enzymes display ≈1/10 of the specific quinol oxidation activity of the wild-type enzyme and unchanged quinol Michaelis constants,
K
m
. The refined x-ray crystal structures at 2.19 Å and 2.76 Å resolution, respectively, rule out major structural changes to account for these experimental observations. Changes in the oxidation–reduction heme midpoint potential allow the conclusion that deprotonation of Glu-C180 in the wild-type enzyme facilitates the reoxidation of the reduced high-potential heme. Comparison of solvent isotope effects indicates that a rate-limiting proton transfer step in the wild-type enzyme is lost in the Glu-C180 → Gln variant. The results provide experimental evidence for the validity of the E pathway hypothesis and for a crucial functional role of Glu-C180.
Alternating Currents of Power: From Colonial to Post-apartheid Spatial Patterns in Newtown, Johannesburg
Authors: Gaule Sally
Published: December 2005

Turbine Square in Newtown, Johannesburg, stands as a metaphor for the changing fortunes of the inner city during the 20th century. Four buildings occupy this site, flanking a small open space. One is the Johannesburg branch of the new South African Reserve Bank (1996); the others are the Boiler Houses (1928) and (1936) and Turbine Hall (1929) that generated electricity for Johannesburg until 1960. The former, completed in 1996, represents one of the first public works of the new democratic South Africa. The latter, icons of Johannesburg in its colonial phase, stand derelict and, until recently, were occupied by squatters. In this examination of Newtown, some social, political and cultural histories of Johannesburg are traced in relation to the city's transition from colonialism to a post-apartheid city. How the spatial layout and symbolism of the built environment form a component of that transition is a theme of this paper.
The Textures of Property Markets: Downtown Housing and Office Conversions in New York City
Authors: Beauregard Robert A.
Published: December 2005

Over the past 10-15 years, many cities in the US have experienced a form of development unknown since World War II-middle-income housing in their downtown cores. Such downtown housing initiatives assume that functional interdependence among different property sectors-office, residential, retail, entertainment-will ensue and that the resultant, co-ordinated investments will produce a lively and attractive downtown environment. This article explores the impediments to this synergism using a perspective that emphasises the 'thicknesses' of property markets; that is, the social, institutional and place-specific qualities of real estate investment. New York City's lower Manhattan revitalisation plan, designed to subsidise office conversions, is used as an example.
Proton Sensing of CLC-0 Mutant E166D
Authors: Traverso Sonia , Zifarelli Giovanni , Aiello Rita , Pusch Michael
Published: December 2005

CLC Cl− channels are homodimers in which each subunit has a proper pore and a (fast) gate. An additional slow gate acts on both pores. A conserved glutamate (E166 in CLC-0) is a major determinant of gating in CLC-0 and is crucially involved in Cl−/H+ antiport of CLC-ec1, a CLC of known structure. We constructed tandem dimers with one wild-type (WT) and one mutant subunit (E166A or E166D) to show that these mutations of E166 specifically alter the fast gate of the pore to which they belong without effect on the fast gate of the neighboring pore. In addition both mutations activate the common slow gate. E166A pores have a large, voltage-independent open probability of the fast gate (popen), whereas popen of E166D pores is dramatically reduced. Similar to WT, popen of E166D was increased by lowering pHint. At negative voltages, E166D presents a persistent inward current that is blocked by p-chlorophenoxy-acetic acid (CPA) and increased at low pHext. The pHext dependence of the persistent current is analogous to a similar steady inward current in WT CLC-0. Surprisingly, however, the underlying unitary conductance of the persistent current in E166D is about an order of magnitude smaller than that of the transient deactivating inward Cl− current. Collectively, our data support the possibility that the mutated CLC-0 channel E166D can assume two distinct open states. Voltage-independent protonation of D166 from the outside favors a low conductance state, whereas protonation from the inside favors the high conductance state.
Single-channel Properties of Human NaV1.1 and Mechanism of Channel Dysfunction in SCN1A-associated Epilepsy
Authors: Vanoye Carlos G. , Lossin Christoph , Rhodes Thomas H. , George Alfred L.
Published: December 2005

Mutations in genes encoding neuronal voltage-gated sodium channel subunits have been linked to inherited forms of epilepsy. The majority of mutations (>100) associated with generalized epilepsy with febrile seizures plus (GEFS+) and severe myoclonic epilepsy of infancy (SMEI) occur in SCN1A encoding the NaV1.1 neuronal sodium channel α-subunit. Previous studies demonstrated functional heterogeneity among mutant SCN1A channels, revealing a complex relationship between clinical and biophysical phenotypes. To further understand the mechanisms responsible for mutant SCN1A behavior, we performed a comprehensive analysis of the single-channel properties of heterologously expressed recombinant WT-SCN1A channels. Based on these data, we then determined the mechanisms for dysfunction of two GEFS+-associated mutations (R1648H, R1657C) both affecting the S4 segment of domain 4. WT-SCN1A has a slope conductance (17 pS) similar to channels found in native mammalian neurons. The mean open time is ∼0.3 ms in the −30 to −10 mV range. The R1648H mutant, previously shown to display persistent sodium current in whole-cell recordings, exhibited similar slope conductance but had an increased probability of late reopening and a subfraction of channels with prolonged open times. We did not observe bursting behavior and found no evidence for a gating mode shift to explain the increased persistent current caused by R1648H. Cells expressing R1657C exhibited conductance, open probability, mean open time, and latency to first opening similar to WT channels but reduced whole-cell current density, suggesting decreased number of functional channels at the plasma membrane. In summary, our findings define single-channel properties for WT-SCN1A, detail the functional phenotypes for two human epilepsy-associated sodium channel mutants, and clarify the mechanism for increased persistent sodium current induced by the R1648H allele.