bluuebunny/crossref_metadata_2025 huggingface dataset:
Concentration dependent size of reversibly assembling polymers in solution: A mean-field lattice theory
Authors: Lenz Peter B. , Hentschke Reinhard
Published: November 2004

The concentration dependence of the mean length of equilibrium polymers, 〈s〉, as a function of solute volume fraction is studied in a lattice description. Using a more detailed model of constituent interactions in comparison to previous studies we are able to find conditions under which a decrease of 〈s〉 at high solute concentration may occur.
Combined electron- and ion-beam imprinter and its applications
Authors: Ji Q. , Ji L. , Chen Y. , Leung K.-N.
Published: November 2004

A combined electron- and ion-beam system employing a double-chamber plasma source and a single accelerator column has been developed to provide focused electron and positive-ion beams simultaneously, with no need for a separate electron source or accelerating column for sample neutralization. The self-aligned ion and electron beams can be used to micromachine and image a variety of materials, both conducting and insulating. Together with an ion-beam imprinting scheme, the combined electron/ion beam system is compact and provides low-cost, high-throughput, and large-area micromachining.
Pulse-pair control of resonance leaking in molecular multiphoton transitions
Authors: Lan Boon-Leong , Vrábel Imrich , Jakubetz Werner
Published: November 2004

We use model five-level systems to study resonance leaking of π-pulse-induced multiphoton (MP) transitions along a strongly coupled anharmonic ladder. We demonstrate that the presence of a weakly bound background state attached to the ladder either in linear or Λ configuration can have very pronounced effects on resonant MP ladder transitions, including essentially complete quenching of the primary transition. We also develop control strategies for the elimination of background state population based on phase-adjusted Gaussian pulse pairs and discuss the underlying control mechanisms. Finally we show that these strategies are effective in realistic molecular many-level systems. In particular, we demonstrate efficient pulse-pair control of resonance leaking in a 165-level system modeling vibrational excitation in HCN.
Calculation of pressure using the virtual-volume-variation method and the virial method from chain conformations obtained by Monte Carlo simulations on the second nearest neighbor diamond lattice
Authors: Rane Sagar S. , Mattice Wayne L. , Choi Phillip
Published: November 2004

For a model system of polyethylene of chain lengths 40 and 100 carbon atoms, we calculated the pressure at different densities and compared them with the experimental values. The simulation was conducted on the second nearest neighbor diamond lattice, and the pressure was calculated using the virtual-volume-variation method after the system was reverse mapped to its fully atomistic form in continuous space and energy minimized. In addition, the pressure was also calculated from the virial route by conducting a short molecular dynamics simulation starting from the energy minimized structure. We show that the pressure obtained from our simulations is quite reasonable in the length of simulation time (in Monte Carlo steps) normally employed in our group. These results provide additional evidence for the equilibration of our model systems, and methodology to calculate the pressure in our lattice models.
Nanotubular boron-carbon heterojunctions
Authors: Kunstmann Jens , Quandt Alexander
Published: November 2004

Linear nanotubular boron-carbon heterojunctions are systematically constructed and studied with the help of ab initio total energy calculations. The structural compatibility of the two classes of materials is shown, and a simple recipe that determines all types of stable linear junctions is illustrated in some detail. Our results also suggest the compatibility of various technologically interesting types of nanotubular materials, leading to different types of nanotubular compound materials, and pointing out the possibility of wiring nanotubular devices within heterogeneous nanotubular networks.
Food chain chaos with canard explosion
Authors: Deng Bo
Published: November 2004

The “tea-cup” attractor of a classical prey–predator–superpredator food chain model is studied analytically. Under the assumption that each species has its own time scale, ranging from fast for the prey to intermediate for the predator and to slow for the superpredator, the model is transformed into a singular perturbed system. It is demonstrated that the singular limit of the attractor contains a canard singularity. Singular return maps are constructed for which some subdynamics are shown to be equivalent to chaotic shift maps. Parameter regions in which the described chaotic dynamics exist are explicitly given.
Unshielded three-axis vector operation of a spin-exchange-relaxation-free atomic magnetometer
Authors: Seltzer S. J. , Romalis M. V.
Published: November 2004

We describe a vector alkali–metal magnetometer that simultaneously and independently measures all three components of the magnetic field. Using a feedback system, the total field at the location of the magnetometer is kept near zero, suppressing the broadening due to spin-exchange collisions. The resonance linewidth and signal strength of the magnetometer compare favorably with two different scalar operation modes in which spin-exchange relaxation is only partially suppressed. Magnetic field sensitivity on the order of 1pT∕Hz is demonstrated in a laboratory environment without magnetic shields.
Structural transformation and field emission enhancement of carbon nanofibers by energetic argon plasma post-treatment
Authors: Weng C. H. , Leou K. C. , Wei H. W. , Juang Z. Y. , Wei M. T. , Tung C. H. , Tsai C. H.
Published: November 2004

Vertically aligned carbon nanofibers (CNFs) grown by plasma enhanced chemical vapor deposition (PECVD) were transformed into cone-shaped nanostructures after treatment by argon (Ar) plasma. Significant enhancement of field emission characteristics of the post-treated CNFs has been achieved. Analysis by electron microscopy and energy dispersive spectroscopy (EDS) suggests that the structural transformation is a result of a cosputtering∕deposition process by energetic plasma ions. The enhancements can be attributed to the combining effects of an additional Si∕C layer coverage, catalytic nanoparticles removal and the sharpening of CNFs tips. The argon plasma post-treatment processes developed here can be easily extended to in situ PECVD processes for fabricating CNFs based emitters.
Observation of red intraligand electrophosphorescence from a stilbene-containing Re(I) complex
Authors: Li Bin , Li Mingtao , Hong Ziruo , Li Wenlian , Yu Tianzhi , Wei Hanzhi
Published: November 2004

Red organic light-emitting diodes using a rhenium(I) bipyridyl complex, fac-[ClRe(CO)3(trans-4-methyl-4′-(2-4-octadecyloxylphenyl)vinyl)-2,2′-bipyridine] (Re-mopvb), as an emitter were fabricated. The optimized device has a bilayer structure of indium-tin oxide∕poly(N-vinylcarbazole): 2 wt. % Re-mopvb (80 nm)∕2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (50 nm)∕LiF (1 nm)∕Al (150 nm). Although no photoluminescence from Re-mopvb in the room-temperature solution appeared due to photoinduced isomerization, a bright red electrophosphorescence from an intraligand excited state of Re-mopvb was observed at room temperature, indicating the promising future of such a class of electroluminescent materials. The maximum luminance exceeding 120cd∕m2 at 11 V and maximum efficiency of 0.75 cd∕A at 7.5 V were obtained.
Low-voltage, polarization-insensitive, electro-optic modulator based on a polydomain barium titanate thin film
Authors: Tang Pingsheng , Towner D. J. , Meier A. L. , Wessels B. W.
Published: November 2004

A BaTiO3 thin-film electro-optic waveguide modulator with a half-wave voltage-interaction length product (VπL) of 1.1Vcm at 1.55-μm wavelength is demonstrated. The half-wave voltage and the measured effective electro-optic coefficient are 3.3V and 162pm∕V, respectively. The half-wave voltage increases less than 10% over a temperature range of 23–90°C. Polarization-independent electro-optic modulation was observed and attributed to the polydomain structure of the BaTiO3 film. The unique combination of large electro-optic coefficient and polarization independence illustrates how engineered domain structures in ferroelectric thin films can enable properties and performance unachievable in bulk single crystals.
Reflection property of nano-acoustic wave at the air∕GaN interface
Authors: Hsieh Chia-Lung , Lin Kung-Hsuan , Wu Shr-Bin , Pan Chang-Chi , Chyi Jen-Inn , Sun Chi-Kuang
Published: November 2004

We present a study on the total internal reflection of nano-acoustic waves (NAWs) at the air∕GaN interface. The coherent NAW was generated and detected by piezoelectric InGaN∕GaN multiple quantum wells using a femtosecond transient transmission technique. With suitably designed sample structures, the fact that strain of the NAW experiences a sign change after total internal reflection at the air∕solid interface is examined directly. The surface roughness of the sample was found to distort the wave front of the NAW and to diminish the measured amplitude of the reflected NAW.
Effects of denuded zone of Si(111) surface on current conduction and charge trapping of HfOxNy gate dielectric in metal-oxide-semiconductor devices
Authors: Cheng Chin-Lung , Chang-Liao Kuei-Shu , Huang Ching-Hung , Wang Tien-Ko
Published: November 2004

This work investigated the effects of interstitial oxygen [Oi] defects at the Si(111) surface on current conduction and charge trapping of metal-oxide-simiconductor devices with HfOxNy gate dielectric. Smaller gate leakage current, stress-induced leakage current (SILC) and defect generation rate, attributable to the decrease of [Oi] defect concentration at the HfOxNy∕Si interface, were observed for devices with denuded zone. The current-conduction mechanism of the HfOxNy films at the low- and high-electrical field was dominated by the Schottky and Frenkel–Poole emissions, respectively. The trapped charges in HfOxNy dielectric were positive. The mechanism related to the SILC at low-electrical field can be explained using the interface trap-assisted tunneling.
Transmission and reflection characteristics of in-plane hetero-photonic crystals
Authors: Song Bong-Shik , Asano Takashi , Akahane Yoshihiro , Tanaka Yoshinori , Noda Susumu
Published: November 2004

We report transmission and reflection characteristics of in-plane hetero-photonic crystals (IP-HPCs) consisting of two serially connected photonic crystal waveguides with differing lattice constants. We show experimentally and theoretically that the transmission spectrum of the structure corresponds to the transmission frequency range common to both waveguides. Also, there exists a frequency gap where the structure has a guiding mode for one waveguide but not for the neighboring one. Our calculated results reveal that light within the common frequency range is transmitted with approximately 100% efficiency through the waveguides while light within the gap is almost perfectly reflected.
Correlation among oxygen vacancies in bismuth titanate ferroelectric ceramics
Authors: Li Wei , Chen Kai , Yao Yangyang , Zhu Jinsong , Wang Yening
Published: November 2004

Pure Bi4Ti3O12 ceramics were prepared using the conventional solid-state reaction method and their dielectric properties were investigated. A dielectric loss peak with the relaxation-type characteristic was observed at about 370K at 100Hz frequency. This peak was confirmed to be associated with the migration of oxygen vacancies inside ceramics. The Cole–Cole fitting to this peak reveals a strong correlation among oxygen vacancies and this strong correlation is considered to commonly exist among oxygen vacancies in ferroelectrics. Therefore, the migration of oxygen vacancies in ferroelectric materials would demonstrate a collective behavior instead of an individual one due to this strong correlation. Furthermore, this correlation is in proportion to the concentration and in inverse proportion to the activation energy of oxygen vacancies. These results could be helpful to the understanding of the fatigue mechanisms in ferroelectric materials.
Energy-dispersive small-angle x-ray scattering for investigating polymer morphology: Static and time-resolved experiments
Authors: Portale Giuseppe , Longo Alessandro , D’Ilario Lucio , Martinelli Andrea , Caminiti Ruggero
Published: November 2004

Energy-dispersive small-angle x-ray scattering couples the information given by small-angle experiments and the advantages of energy-dispersive methods, mainly in carrying out time-resolved experiments. Preliminary small-angle measurements on some semicrystalline polymers using a laboratory-based energy-dispersive diffractometer and the bremsstrahlung continuum generated from a commercial tube as x-ray source are presented. The results are in agreement with those obtained with the classical method. The apparatus utilized could be considered a promising tool to perform both wide and small-angle scattering or diffraction.
Wave fields measured inside a negative refractive index metamaterial
Authors: Cummer Steven A. , Popa Bogdan-Ioan
Published: November 2004

Measured spatial variations of field phase and amplitude versus position inside a wire/split ring resonator negative refractive index metamaterial are presented that show that the phase velocity inside a negative index material points toward the source and consequently that phase velocity and energy flow are reversed in such a medium. These measurements directly demonstrate the fundamental behavior of electromagnetic waves in a negative refractive index material. The same internal field measurements are also used to accurately and reliably measure the effective bulk properties of the negative index metamaterial.
Electrical conduction properties of n-type Si-doped AlN with high electron mobility (>100cm2V−1s−1)
Authors: Taniyasu Yoshitaka , Kasu Makoto , Makimoto Toshiki
Published: November 2004

For n-type Si-doped AlN, we have obtained an electron mobility and concentration of 125cm2V−1s−1 and 1.75×1015cm−3 at 300K, respectively. At 250K, the mobility reached the maximum of 141cm2V−1s−1. To explain the temperature dependence of the mobility, we calculated mobilities limited by specific scattering mechanisms. We found that the mobility is limited by neutral impurity scattering rather than ionized impurity scattering or lattice scattering because of a large donor ionization energy (∼250meV).
Methods for egg counts and larval cultures for strongyles infesting the gastro-intestinal tract of cattle
Authors: Roberts FHS , O'Sullivan PJ
Published: November 2004

The method for egg counts is a modification of the Whitlock-Gordon technique for sheep strongyles and has been developed for low-plane infestations. It uses a three-gram faecal sample and an egg-counting slide of four 0.5-ml. cells. Satisfactory larval cultures are obtained by mixing dry, sterile cattle dung with the fresh faeces. A modified Baermann technique is used for recovering larvae from cultures.
The resistance of Oro and Orfed wheats to Tilletia caries and Tilletia foetida
Authors: Pugsley AT
Published: November 2004

A study has been made of the resistance of Oro and a derived crossbred, Orfed, to one race of Tilletia caries and three races of Tilletia foetida. Rapier and Dirk were used as the susceptible parents in crosses with Oro and Orfed respectively. Two methods were used in the genetic analysis of resistance to the four races. The frequency distribution of bunt infection in segregating F3 populations from the cross Oro X Rapier indicated that inheritance was not simple and this was confirmed by the fact that it was possible to select a number of strains exhibiting marked differential reactions to the four physiologic races. Some selections had an overall resistance greater than that of the Oro parent.
In a backcross programme with Orfed as the donor parent and Dirk as the recurrent parent, it was possible to select strains with a resistance superior to that of Orfed.
In both series of crosses, selections were secured which possessed a high resistance to races L.1 and L.14, and at the same time a high degree of susceptibility to races T.5 and L.3.
Inheritance of skin folding (wrinkling) of sheep
Authors: Kelley RB
Published: November 2004

The Mendelian technique for investigating methods of inheritance was employed to discover the mechanism which controlled skin folding in sheep. Experimental matings were designed to use, for P1 and P2, Border Leicester and wrinkled Merino sheep. These were considered possibly homozygous or nearly so for plain body and wrinkling and had the opposed characteristics of no skin folding and a high degree of it respectively. The matings progressively gave rise to F1, F2, and F3 generations. Subsequently a backcross was made by mating F1 and P2. The investigation discloses that skin folding, or wrinkling, and the absence of skin folding, or plain body, are paired genetically as the two extremes of a range of characterization in which the ultimate types may be homozygous. Within this multifactor situation genes responsible for plain body are possibly associated with epistatic effects. The situation gives rise to a series of heterozygous intermediates from which samples with particular gene frequencies may be withdrawn as breeds of sheep with defined characterization. Estimates of the heritability of either plain body or wrinkling within the samples will vary according to the particular gene frequency for which any estimate is made.
Studies on fluorosis of sheep. 1. The toxicity of water-borne fluoride for sheep maintained in pens
Authors: Peirce AW
Published: November 2004

Five groups, each of six sheep, were fed in pens on an adequate diet of chaffed hay and crushed grain for 3½ years. One group was given rain-water to drink, whereas the others were offered similar water to which sufficient sodium fluoride had been added to give final concentrations of 2.5, 5, 10, or 20 p.p.m. F. The mean daily intakes of fluoride, expressed as fluorine, by the four experimental groups were approximately 5, 9, 18, and 37 mg. F respectively during the winter months and 7, 13, 27, and 53 mg. F respectively during the summer months. The ingestion of fluoride appeared to have no adverse effect on general health, food consumption, or wool production. The mean weights of all groups were approximately the same throughout the experiment except at the end of 2½ years, when the weight of the group which received water containing 20 p.p.m. F was significantly less, but only at the 5 per cent. level, than that of either the control group or the groups receiving the lowest two intakes of fluoride. Mottling of the incisors and molars was only slight among the sheep which received water containing 5 p.p.m. F. It was more evident in the 10-p.p.m. group and was marked in the 20-p.p.m. group. Selective abrasion of the molars was pronounced in this last group but was also noticeable in the 10-p.p.m. group. Fluoride intake caused the incisors to erupt at an earlier age. Ingestion of fluoride brought about increases of up to twentyfold in the fluoride content of the bones and teeth. The bearing of these results on enzootic dental fluorosis among grazing sheep in Queensland is discussed.
The effect of molybdenum and of lime dressings on the copper and molybdenum contents of some pasture species in the Murray Valley.
Authors: Dick AT
Published: November 2004

Dressings of 2 oz. and 2 lb. of ammonium molybdate with and without 1 ton of ground limestone per acre were applied to 0.03-acre plots of the natural pasture at Barooga Field Station in a latin square design with six replications; the other two treatments were 1 ton limestone only and untreated. In the autumn of the following gear one-half of each plot was retreated at the same rate of dressing as in the previous winter. Samples were collected at intervals of those species which formed an appreciable proportion of the pasture, and their copper and molybdenum contents determined. It was found that dressings with up to 2 lb. of ammonium molybdate or 1 ton of limestone per acre, or both, had no effect on the copper content of the pastures. The uptake of molybdenum varied considerably amongst the species; the legumes took up the greatest amount. The molybdenum content of Heliotropium europaeum was practically unaffected by the dressings used.
The aetiology of Phalaris staggers in sheep. I. Preliminary observations on the preventive role of cobalt.
Authors: Lee HJ , Kuchel RE
Published: November 2004

During the course of an experiment, a "staggers" syndrome developed in Merino ewes which selectively grazed freshly growing Phalaris tuberosa. The symptoms and progress of the disease are described and the toxicity of phalaris is discussed. There was no incidence of staggers amongst 10 ewes which were dosed each week with 7 mg. cobalt, while 11 of 15 untreated ewes were affected, six of them fatally. This response to cobalt is highly significant ( P = 0.00054). In the light of these observations, earlier work relating to "phalaris staggers" is reviewed.
Dependence of residual milk in the udder of the cow upon total yield; its bearing upon supposed inhibition of secretion.
Authors: Turner HG
Published: November 2004

In order to examine the influence of variations in yield upon the amount of milk remaining in the udder after milking, residual milk was determined in each of 10 cows following several normal milkings. By varying the interval since the last milking, a range of amounts of milk in the udder at the start of milking was obtained. The data reveal significant correlation between residual milk and total milk, both within and between cows. The regression coefficients are 0.1573 ± 0.0341 within cows and 0.3216 ± 0.0728 between cows. When intervals between successive milkings are unequal it is, therefore, incorrect to assume that yield at any milking represents the amount of milk secreted during the preceding interval. It is pointed out that the interpretation of data purporting to measure the inhibition of secretion caused by long intervals between milkings may consequently have to be greatly modified.
Effects of lime and copper on subterranean clover grown on acid soil.
Authors: McLachlan KD
Published: November 2004

The results of a field experiment on two acid podzolized soils in the Heytesbury area, Victoria, are presented. Nutrient elements were tested on a phalaris (Phalaris tuberosa L.) - subterranean clover (Trifolium subterraneum L.) pasture on an area cleared from heath and on an adjoining area cleared from timber with an understorey of heath. Responses of clover to lime and copper, and interactions between these treatments were obtained. There was no response to potash, zinc, manganese, molybdenum, iron, magnesium, or boron on either soil. Lime increased the yield of clover at both sites, the greater effect occurring on the area cleared from timber. The effect of lime was not due to the release of soil molybdenum. Lime corrected defective nodulation, increased the survival of the plants, and to some extent also increased the yield of individual plants. The relative significance of these effects of lime in determining the final yield of clover per acre is discussed. The effect of copper was very different on the two soils. On the area cleared from heath, copper deficiency was severe. Here, copper increased the yield in the absence as well as in the presence of lime. The effect was considerably greater in the presence of lime, and this positive interaction was highly significant. Copper increased the number of plants per unit area and the yield of individual clover plants. On the area cleared from timber, copper decreased the yield in the absence of lime. Where lime had been applied, the effect of copper on the yield, though not significant, was positive. The evidence presented indicates that copper is also required on this soil. A copper deficiency symptom of subterranean clover is described. It is suggested that the copper status of the soils may influence the distribution of trees in the area.
The root-nodule bacteria as factors in clover establishment in the red basaltic soils of the Lismore district, NSW. III. Field inoculation trials.
Authors: Jenkins HV , Vincent JM , Waters LM
Published: November 2004

Field experience with crimson and subterranean clovers grown in the Lismore red soils has confirmed the importance of successful inoculation with an effective strain of a root-nodule bacterium. Strains of rhizobia, applied singly or in a mixture, differed markedly in their ability to form nodules in the red soils. A relatively heavy dose of inoculum (c. 10 times the usual) was desirable. Superphosphate and dolomite were favourable to nodulation but a trace element mixture that included copper sulphate at the rate of 10 lb per acre proved markedly toxic when put in the drill with inoculated seed. Yield was directly related to the proportion of plants effectively nodulated, whether the latter varied because of the nature of the inoculum or because of fertilizer treatment. Results of inoculation at other centres in the district were very satisfactory. Success has also been obtained with the inoculation of Medicago, pea, and vetch.
Some aspects of the toxicity of 3-(p-Chlorophenyl)-1,1-Dimethylurea (CMU) to plants.
Authors: Levi E
Published: November 2004

The action of 3- (p-chloropheny1)-1,1-dimethylurea (CMU) on both annual and perennial plants was studied. It was found to be a very powerful plant poison acting almost entirely through the root system, even though foliage applications a t high rates caused desiccation and abscission of leaves. No translocation of this chemical from shoot to root was detected.
The short-term effects of rock phosphate and super-phosphate on a subterranean clover pasture.
Authors: Rossiter RC , Ozanne PG
Published: November 2004

A 2-year field experiment is described, in which an annual-type pasture was grown on a soil of lateritic origin with various initial rates of rock phosphate and superphosphate. The soil was acutely deficient in plant-available phosphorus at the outset. Application of superphosphate led to the expected increases in total pasture production, but rock phosphate also gave substantial yield increases, even during the first season. Differential species effects were noted; subterranean clover (Trifolium subterraneum L.) and cape-weed (Cryptostemma calendula Druce) responded about equally to superphosphate, but the clover responded to rock phosphate to a greater extent than did cape-weed. Both relative efficiency for total plant growth and percentage utilization of applied phosphorus were much higher with the soluble phosphatic fertilizer than with rock phosphate, especially in the first year. However, phosphorus recovery from rock phosphate was as high in the second year as in the first, whereas there was a marked decrease in the second year from superphosphate.
Blood inorganic phosphorus and serum potassium in insulin hypoglycaemia in the sheep.
Authors: Setchell BP , McClymont GL
Published: November 2004

The effect of subcutaneous and intravenous insulin on the blood glucose, blood inorganic phosphorus, and serum potassium levels of fasted sheep has been studied. Depression of blood inorganic phosphorus and of serum potassium, as well as of blood glucose, followed the injection of insulin by both routes. The depressions in blood inorganic phosphorus and serum potassium approximately paralleled those of the glucose with both subcutaneous and intravenous insulin, but the blood inorganic phosphorus remained depressed for a mnch longer time than either blood glucose or serum potassium.
Inheritance of birthcoats in a strain of Merino sheep.
Authors: Schinckel PG
Published: November 2004

Further observations on the inheritance of birthcoat grade in a flock of South Australian strain of Merino sheep are reported. These observations indicate that the inheritance is multifactorial and that the phenotypic variation is adequately accounted for by an additive genetic situation. The heritability of birthcoat grade was found to be 0.70 ± 0.035 from the regression of offspring on mid-parent and of the order of 0.72-0.78 from full-sib correlations. A difference, highly significant statistically, was observed between the birthcoat grade of ram and ewe lambs. Ewe lambs tended to be 0.35 grade coarser than ram lambs. Examination of published data (Rendel 1954) revealed that a similar difference also occurs between the sexes in the Welsh Mountain breed. A significant deficiency of female progeny was observed among the offspring of fine birthcoat ewes. There is no ready explanation of this loss but it almost certainly results from pre-natal death of a proportion of female embryos carried by fine ewes.
Multifactorial inheritance of Halo-hair abundance in New Zealand Romney sheep.
Authors: Dry FW
Published: November 2004

Halo-hair abundance is strongly inherited in sheep less than N-grade. The tabulated breeding results have the appearance of typical multifactorial inheritance. Lambs without halo-hairs on the back probably vary in the genetic margin by which they have escaped growing halo-hairs there. Further work is desirable on the inheritance of great freedom from halohairs on the extremities, especially the britch, and its significance for fleece characterization. Either one or two many-halo rams (not N-grade) bred from, which did not sire any N-grade lambs, may have been N /+. The same problem of poor expressivity is posed by many-halo rams judged N /+ that sired very few N-grade lambs. Further breeding experiments are called for, both with sheep less than N-grade known to be N /+ and their descendants, and with many-halo sheep from Romney flocks.
Observations on infestations of undipped cattle of British breeds with the cattle tick, Boophilus microplus (Canestrini).
Authors: Wilkinson PR
Published: November 2004

A small herd of cattle infested with the cattle tick, Boophilus microplus (Canestrini) was kept in a previously unstocked paddock for 11 months without treatment for tick infestation. Frequent examinations showed that widely differing numbers of ticks developed on the cattle. The "tick resistance" of one animal, which showed no adult ticks during the summer months, could only be accounted for by mortality of the larvae and nymphs on the animal, since as many larvae were seen on selected small areas of this animal as on some animals carrying many adult ticks. The animals grazed together and thus would encounter similar numbers of tick larvae. The degree of susceptibility to adult tick infestation showed negligible correlation with skin thickness measurements and was not related to coat length. Larvae reappeared on the cattle 6 weeks after the first stocking of the paddock in March. The animals became almost free of ticks for 2 weeks in August. Although larvae were most numerous in November-December, they gave rise to fewer adults than the earlier wave of larvae in September- October. Some of the cattle suffered from "tick-worry'' in October, but thereafter their condition improved without treatment.
The effect of self-licking by cattle on infestations of cattle tick, Boophilus microplus (Canestrini)
Authors: Snowball GJ
Published: November 2004

Infestations of Boophilus microplus (Canestrini) were established by applying single batches of larvae to individually stalled cattle, and the percentage yields of engorged female ticks from animals kept in harness to impede licking were compared with those from animals allowed to lick freely. In the harness trials, 33 per cent. of female ticks survived to fall as engorged adults from the host; in individual infestations this survival ranged from 5 to 69 per cent. In the trials without harness the corresponding survival was 9 per cent., ranging from 0.1 to 32 per cent. Statistical analysis showed a highly significant effect of harness in promoting survival of ticks. Licking (and other forms of host behaviour, e.g. kicking and rubbing, which produce tick mortality by mechanical means) must be considered in any study of natural mechanisms regulating cattle tick populations.
An experimental investigation of the hepatotoxic and other effects on sheep of consumption of Heliotropium europaeum L. : Heliotrope poisoning of sheep
Authors: Bull LB , Dick AT , Keast JC , Edgar G
Published: November 2004

Experiments were conducted in which two flocks of breeding ewes were grazed on natural pastures containing H. europaeum L. A third flock was grazed on an area on which irrigation water was used to favour germination and early growth of the plant. After the sheep had grazed the plant for the first period, a small proportion, from 1 to 7 per cent., died with damaged livers. After they had again grazed the plant during the following year, the death rate from liver disease rose to 50 per cent. in the exploratory experiment, to 38 per cent. in the first controlled flock experiment, and to 70 per cent. in the second controlled flock experiment. Haematogenous jaundice was present in approximately half the sheep that died. Haemoglobinaemia with haemoglobinuria was present, usually in a mild form, in 31 per cent. of the deaths during the second year of the first controlled experiment, and in 5 per cent. during the second year of the second controlled experiment. In the autumn and spring when the pastures were lush, many of the sheep while in good bodily condition died suddenly without being seen to be sick. Later, most of the deaths were in sheep that had lost condition. Clinical pathological examinations showed that the affected sheep commonly exhibited a fall in haemoglobin and a rise in bilirubin in the blood. Tests showed a fall in prothrombin values. There were indications of a fall in plasma albumen, and also a fall in ability to store glucose. Chemical analyses of livers collected from sheep that died showed the copper concentration to be above normal values, approximately 80 per cent. being over 1000 p.p.m. Histopathological examinations of livers showed that the pathognomonic change was an increase in size of the liver cells associated with their increased death rate and loss of regenerative powers. The changes resulted in an atrophic hepatosis with little replacement fibrosis. There was an accumulation of ceroid in the livers, and a terminal occurrence of inclusion globules in the liver cells. Related field investigations confirmed the findings of the experiments, and showed that the liver damage produced by the consumption of H. europaeum predisposed sheep to the haemolytic crisis of chronic copper poisoning.
The effect of light on the breeding season, gestation, and birth weight of Merino sheep
Authors: Yeates NTM
Published: November 2004

Peppin strain Merino ewes, when running continuously with vasectomized rams, exhibit a definite seasonality in the incidence of oestrus. Although less decisively separated into seasons of quiescence and activity, the oestrous pattern resembles that of the British breeds of sheep. The pattern may be reversed by artificially reversing the seasonal trend of daylight duration. This is presumptive evidence that the natural breeding season of Merinos is regulated by seasonal fluctuations in the length of day. Though there was no evidence of it in this experiment, some Merinos are believed to commence their breeding season before the days begin to shorten. This is not necessarily irreconcilable with photoperiodic control, and such animals may represent a variant genetic type. Pregnant ewes, subjected during winter-time to a summer level of light, produced lambs of normal birth weight following a gestation of normal length. This finding helps to isolate summer heat as the factor responsible for the low birth weight sometimes reported of lambs produced out of season.
Maintenance rations for Merino sheep. IV. The performance of adult Merino ewes fed daily and weekly at three levels of energy intake
Authors: Briggs PK , Franklin MC , McClymont GL
Published: November 2004

Dry adult Merino ewes were fed at daily or weekly intervals on oat grain at levels which provided 4.0, 3.0, or 2.0 lb starch equivalent (S.E.) per sheep per week. The experimental periods were 223, 223, and 181 days respectively. Differences between the mean body weights of the ewes a t the three levels of feeding were highly significant (P < 0.001). Body weight varied only slightly and no losses occurred in ewes fed weekly at the rate of 4.0 lb S.E. per head. Ewes fed daily a t this level had a significantly greater mean body weight (P < 0.001) a t the conclusion of the 223-day experimental period. The addition of a sodium chloride supplement did not improve the body weight or wool production of ewes fed weekly a t the level of 4.0 lb S.E. The mean body weight of ewes fed at the levels of 3.0 or 2.0 lb S.E. per head declined over the first 12 and 18 respectively and thereafter remained relatively constant. There were no significant differences at these levels of feeding between groups fed daily and weekly in respect of body weight, wool production, or survival rates. Ewes fed a t the level of 4.0 lb S.E. grew significantly more wool than those given 3.0 lb S.E. (P < 0.001). Losses were negligible in all groups except those fed a t the level of 2.0 lb S.E. In these groups there were few deaths in the first 16 weeks, but in the subsequent 10 weeks losses totalled 17.1 per cent. Ewes fed a t the level of 2.0 lb S.E. consumed their rations at a significantly slower rate (P < 0.01) than did those fed a t the level of 4.0 lb S.E.
Methionine supplements in chicken diets. 1. Effects of supplementary methionine and choline on growth and folic ancid requirements of White Leghorn chickens
Authors: McDonald MW
Published: November 2004

The addition of 0.2 per cent. DL-methionine to a diet based on wheatmeal, meatmeal, and whey powder produced a 12 per cent. increase in weight a t 6 weeks in White Leghorn chickens. Although the addition of 4.4 p.p.m. of folic acid to the basal diet produced no response, the addition of folk acid to the methionine-supplemented diet produced a further 7 per cent. increase in weight. In a second experiment, supplementing the same basal diet with 0.066 per cent. choline chloride produced a 17 per cent. growth depression which was prevented by the addition of folic acid. Methionine (0.2 per cent.), added to the basal diet supplemented with 0.066 per cent. choline chloride and 4.4 p.p.m. folic acid, produced a 5 per cent. growth increase, proving that the basal diet was deficient in sulphur-amino acids. It is suggested that folk acid is required for the catabolism of methyl groups provided in excess of the chicken's requirements.
Seed size as a factor in the growth of subterranean clover (Trifolium subterraneum L.) under spaced and sward conditions
Authors: Black JN
Published: November 2004

The significance of seed weight in the growth of subterranean clover (Trifolium subterraneum L) , of the Bacchus Marsh strain, has been assessed under both spaced plant and sward conditions at the Waite Agricultural Research Institute. Under conditions of spacing, plants of three widely separated seed size grades were grown a t a density of 1 per 25 sq. links. The dry weights of the plants were proportional to seed weight from the time of sowing (in May) till the end of October – over almost the entire growing period of the crop. Three sets of swards were grown a t a density of 25 plants per sq. link, each sward being planted with seed of one of the three sizes. Dry weight was proportional to seed weight in the early part of the season but when the swards reached a leaf area index of about 4 (i.e. when there were 4 sq. links of leaf surface on 1 sq. link of ground), a reduction in growth rate occurred. This critical leaf area index was reached first in "large seed" swards, followed later by "medium seed" and finally by "small seed" swards. Thus there was a period in which the swards were growing at different rates, and in which the dry weights came to parity, so that on the final sampling occasion (in December) there was no significant difference between the dry weights of the swards from the three seed sizes. It is concluded that a t a leaf area index of about 4, interception of incident light energy is complete.
Ecological observations on the cattle tick, Boophilus microplus (Canestrini)
Authors: Snowball GJ
Published: November 2004

Studies were undertaken during 1948-1950 on Boophilus microplus under field conditions in southern Queensland to determine the duration of the non-parasitic stages, and to relate this information to tick incidence on cattle. In the area where the observations were made, the population of ticks on cattle is high in summer and autumn and low in minter and spring. Each week throughout the investigation engorged female ticks, freshly fallen from cattle, were placed in a pasture plot and their subsequent history recorded. Concurrently, observations were made on the changes in tick population on a dairy herd on an adjacent farm. Female ticks exposed on the plot between April and July produced virtually no progeny, and it is probable that the ticks in the pasture traversed by the dairy cattle exhibited a similar, though less severe, inhibition of reproduction. This failure to reproduce, combined with the dying out of larvae and protracted developmental periods of eggs, reduced to very low levels the larval population available to infest cattle during the months of August–October. Ticks exposed from late July to the following autumn produced progeny. There was a tendency for the progeny of ticks exposed in the late winter and early spring to hatch a t about the same time in the late spring, and this synchronous hatching was probably responsible for the 'spring rise' in tick population on cattle. It appears likely that the engorged female adults dropped in the early autumn represent the most important stage in the overwintering of the species in this area. Some of their larvae survive the adverse winter conditions, either in the free-living or the parasitic stage, and give rise to adults, which fall in the late winter and spring, and which in turn produce the larvae of the spring rise.
Strategic dipping for control of the catle tick, Boophilus microplus (Canestrini), in South Queensland
Authors: Norris KR
Published: November 2004

In the spring and early summer of 1953, three cattle herds in south Queensland were dipped in acaricides at intervals such that few or none of the cattle ticks (Boophilus microplus) attacking to the animals between dippings reached maturity. This was continued until the tick larvae hatching in the pastures in spring were greatly depleted in numbers, but was discontinued before they were exterminated, to avert the danger of the cattle losing their immunity to redwater fever. Throughout the rest of the summer and the early autumn these cattle were lightly infested, and required dipping relatively infrequently. On the other hand, on a property where early, intensive dipping had not been carried out, very heavy infestations of ticks were present throughout the summer and autumn in spite of monthly dippings. This procedure of relating times of dipping to the ecology of the tick has been termed "strategic dipping". In the 1954-55 season, results obtained by intensive spring and early summer dipping were not comparable with those of the 1953-54 season. This appeared to be attributable principally to delayed or relatively ineffective dippings at critical times. Effective application of strategic dipping, as during the 1953-54 season, would reduce the need for acaricidal treatment of the cattle in the summer months when dipping is likely to be delayed by rainy periods.
The soil structure profile under pastures
Authors: Greacen EL
Published: November 2004

It has been found that under reconditioning pastures the soil develops a strongly differentiated structure profile within normal ploughing depth. Aggregation (2 mm) as measured by the wet sieving technique was, for short-term subterranean clover and ryegrass pastures, high at the surface but decreased rapidly with depth. In contrast to this, a more vigorous dispersion test showed that the crumbs of these highly aggregated surface layers broke down to give a greater amount of fine material (<50 µ) than did soil from below the old 3-in. cultivation depth. A demonstration of the practical implications was obtained on ploughing in a 3-year pasture. Chisel, mould board, and disc ploughs were used at three depth settings. Where the structure profile was inverted or mixed, infiltration rate and porosity were better maintained during a winter fallow than when the soil was loosened but not inverted.
The influence of various factors on some methods of estimating fibre and follicle population density in the skin of Merino sheep. I. Methods of delineating area of natural skin
Authors: Carter HB , Turner HN , Hardy MH
Published: November 2004

Many factors may influence measurement of skin area for estimation of fibre or follicle population density. This paper analyses the influence of method of delineation (hairpin calliper, Hardy clipper, or Carter biopsy punch), type of sheep (wrinkled or plain), body region, and sheep individuality on the mean density estimated and on the error of estimation. With either a biopsy punch or a 1 in.2 hairpin calliper in the midside region, sampling errors of the order of 8–11 per cent. were found for density estimates in a series of field observations on Merino and Corriedale ewes, with between-sheep coefficients of variation ranging from 13 to 18 per cent.
Pasture studies on the coastal lowlands of Subtropical Queensland. III. The nutrient requirements and potentialities of Desmodium uncinatum and white clover on a lateritic podzolic soil
Authors: Andrew CS , Bryan WW
Published: November 2004

Nutrient deficiencies in a lateritic podzolio soil typical of the eucalypt ridges of the coastal lowlands of south-eastern Queensland, as measured by the responses of Desmodium uncinatum (Jacq.) DC, and white clover (Trifolium repens L.), are reported and discussed. The soil is grossly deficient in phosphorus and nitrogen; other severely limiting nutrients are calcium, copper, sulphur, and, somewhat later in growth, potassium. Molybdenum and zinc are less limiting to growth, but additions of them may be needed as pastures become older. It is possible that boron may also be i11 short supply for some species. White clover responded well to additions of copper, but Desmodium did not. It would also appear that white clover requires more calcium than D. uncinatum. The results for this soil are in general agreement with those obtained on the gley soils in the region. The two soils are sufficiently different in their water relations for white clover to thrive on the gleys (wet soils) and to be short-lived on the podzolic (dry) soils where it is subject to attack by nematodes. D. uncinatum shows promise as a pasture legume on both soil types. This is the first recorded use of D. uncinatum as a pasture legume under field conditions. The results quoted are from ungrazed trials; however, in other experiments D. uncinatum has been maintained under intermittent and at times very close grazing by sheep. Yields of approximately 2 tons of dry matter/acre/year have been obtained once this species is well established. The nitrogen content of the material is 3.2–3.6 per cent. These figures indicate that this species, which has persisted for up to 4 years on each soil type, can be made a valuable component of subtropical coastal pastures.