bluuebunny/crossref_metadata_2025 huggingface dataset:
High tunability (Ba,Sr)TiO3 thin films grown on atomic layer deposited TiO2 and Ta2O5 buffer layers
Authors: Kim Il-Doo , Tuller Harry L. , Kim Hyun-Suk , Park Jin-Seong
Published: November 2004

In this letter, we report on increased tunability of Ba0.6Sr0.4TiO3 (BST) thin films by use of Ta2O5 and TiO2 films as buffer layers between BST and Si substrates. Ta2O5 and TiO2 buffer layers were grown by atomic layer deposition (ALD) onto Si substrates followed by pulsed laser deposition of Ba0.6Sr0.4TiO3 thin films onto the buffer layers. The randomly oriented BST films deposited on TiO2∕Si substrates exhibited a broader grain size distribution than the (110) textured BST films grown on Ta2O5∕Si substrates. At an applied voltage of 10 V, the BST films grown on Ta2O5∕Si and TiO2∕Si substrates showed much enhanced tunability values of 53.1% and 72.9%, respectively, as compared to the 20.7% value obtained with BST films grown on MgO single crystal substrates. Successful integration of BST low voltage microwave tunable devices onto Si substrates thus appears possible with the aid of ALD grown Ta2O5 or TiO2 buffer layers.
Temperature-dependent molecular conduction measured by the electrochemical deposition of a platinum electrode in a lateral configuration
Authors: Kim B. , Ahn S. J. , Park J. G. , Lee S. H. , Park Y. W. , Campbell E. E. B.
Published: November 2004

Temperature-dependent current–voltage (I–V) characteristics of a molecule, 1,4-benzenedimethanethiol, was measured for 30K<T<300K by a method of contact made by the electrochemical deposition of a platinum electrode in a lateral configuration. The I–V characteristics are nonlinear and asymmetric in the entire temperature range and the current decreases with decreasing temperature down to 40K. Below 40K, the I–V characteristics become temperature independent. The asymmetric I–V characteristics can be understood as arising from a better contact on one side (made by the self-assembled monolayer) than on the other side (made by the electrochemically deposited Pt electrode). The activation energy of thermally activated conduction for T>100K is typically 0.11eV. For T<40K, the observed temperature independent I–V characteristics are fitted to the Fowler–Nordheim tunneling expression with barrier height of 1–2eV depending on the contact strength of samples.
Pulsed laser induced spontaneous gratings on a surface of azobenzene polymer
Authors: Tsutsumi Naoto , Fujihara Arata
Published: November 2004

Self-organized spontaneous gratings were induced on a surface of azobenzene polymer by an irradiation of frequency doubled neodymium doped yttrium–aluminum–garnet pulsed laser. Irradiation of uniform single laser beam at normal incidence induced periodic line shaped structures on a polymer surface. The structure is so-called laser induced periodic surface structure (LIPSS) which was formed along the direction parallel to the polarization direction of pulsed laser. The LIPSS was formed above the critical thickness around 60nm. Irradiation of s-polarized holographic interference beams induced the distinguished holographic surface relief grating (SRG) structures. Irradiation of p-polarized holographic interference beams induced egg crate-like (ECL) structures. A combination of holographic SRG and sequential LIPSS is the likely cause of the ECL patterns observed in this work.
Simulation of gate lag and current collapse in gallium nitride field-effect transistors
Authors: Braga N. , Mickevicius R. , Gaska R. , Shur M. S. , Khan M. Asif , Simin G.
Published: November 2004

Results of two-dimensional numerical simulations of gate lag and current collapse in GaN heterostructure field-effect transistors are presented. Simulation results clearly show that current collapse takes place only if an enhanced trapping occurs under the gate edges. Hot electrons play an instrumental role in the collapse mechanism. The simulation results also link the current collapse with electrons spreading into the buffer layer and confirm that a better electron localization (as in a double heterostructure field-effect transistor) can dramatically reduce current collapse.
Two-dimensional planar size effects in epitaxial PbTiO3 thin films
Authors: Lee Kilho , Kim Keewon , Kwon Soon-Ju , Baik Sunggi
Published: November 2004

In order to test a critical lateral dimension in two-dimensional (2D) planar ferroelectrics, epitaxial PbTiO3 thin films are patterned into discrete islands lithographically with different lateral sizes. As the pattern size decreases, the substrate clamping effect is significantly reduced and thus the misfit strain in the films could be relaxed further. Evolution of 90° domain structures as a function of lateral dimensions was characterized extensively by reciprocal space mapping using synchrotron x ray. As the lateral 2D planar size decreases in the PbTiO3 patterns on MgO(001), some of the a domains turned into c domains due to the relaxed tensile strain. In the PbTiO3 patterns on Pt(001)∕MgO(001), on the other hand, the formation of 90° domains is enhanced by the reduction in compressive misfit strain. Equilibrium domain structures in the PbTiO3 thin film islands are also analyzed by the finite element simulation and found to be consistent with the experimental observation.
Time- and spectrally resolved ultrafast gain dynamics of a semiconductor optical amplifier under phase-correlated multiwavelength pulse amplification
Authors: Archundia Luis C. , Resan Bojan , Delfyett Peter J.
Published: November 2004

The ultrafast gain dynamics of an AlGaAs semiconductor optical amplifier (SOA) are measured under phase-correlated multiwavelength pulse amplification using time-resolved pump–probe techniques. Both the temporal and spectral gain dynamics are measured. Carrier heating due to two photon absorption, carrier cooling, four-wave mixing, and cross-phase modulation effects are observed. These effects are evident when amplifying dispersion compensated pulses, and it is shown how these effects decrease when amplifying nondispersion compensated (chirped) pulses. This helps to avoid nonlinear effects in the gain media (SOA), which, in turn, helps to support the operation of external cavity multiwavelength semiconductor mode-locked lasers where the intracavity pulses are inherently chirped.
Dielectric nonlinearity in relaxor and ferroelectric thin films of chemically ordered PbSc0.5Nb0.5O3
Authors: Tyunina M. , Levoska J.
Published: November 2004

Dynamic nonlinear dielectric response of pulsed laser deposited epitaxial thin films of chemically ordered perovskite PbSc0.5Nb0.5O3 was experimentally studied and analyzed. Films deposited at 925K exhibited relaxor-like behavior indicated by frequency dispersion of temperature of dielectric maxima Tm, maximum in third-order dynamic nonlinear permittivity ε3(T), and increase of scaled dynamic third-order nonlinear permittivity asc below Tm. With decreasing deposition temperature, relaxor behavior was suppressed. Results are discussed in terms of film microstructure and random field strength.
Ultrafast nonresonant third-order optical nonlinearities in ZnSe for photonic switching at telecom wavelengths
Authors: Major A. , Yoshino F. , Aitchison J. S. , Smith P. W. E. , Sorokin E. , Sorokina I. T.
Published: November 2004

We report the steady-state and time-resolved z-scan measurements of the nonresonant third-order optical nonlinearities in ZnSe at telecom wavelengths. The measurements demonstrate that ZnSe could be used for ultrafast all-optical switching at 1310 and 1550nm.
Interface-related thickness dependence of the tunability in BaSrTiO3 thin films
Authors: Ellerkmann U. , Liedtke R. , Boettger U. , Waser R.
Published: November 2004

The thickness dependence of the tunability of Ba0.7Sr0.3TiO3 thin films is investigated. The capacitance–voltage curves, revealing the tunability of the films with thickness from 30 to 370nm, show a strong thickness dependence. This is attributed to a bias-independent interface capacity. The interface suppresses the permittivity of the film with increasing influence for decreasing film thickness, whereas the tunability of the bulk of the film remains constant. Calculations are performed from a thermodynamic model based on the Landau–Ginzburg–Devonshire theory leading to the assumption of the bias-independent interface capacity. The bias dependence of the bulk of the films derived from measurement data are in very good agreement with the theoretically derived values.
Electron side-emission from corrugated CNx nanotubes
Authors: Che R. C. , Peng L.-M. , Wang M. S.
Published: November 2004

Horizontally grown and vertically aligned carbon nitrogen (CNx) nanotubes encapsulated with Fe2O3 particles were synthesized on silicon substrates. Electron field-emission measurements were carried out on these CNx nanotubes using both the top-emission and side-emission geometries, and compared with that of the usual carbon nanotubes (CNTs). It was found that the turn-on field of the CNx nanotubes is at least ∼2V∕μm less and the field conversion factor under low bias voltage is about four times more than that of the CNTs. For the two types of CNx films, the field emission property of the horizontally grown honeycombed film is clearly better than that of the vertically aligned film, indicating that for the corrugated nanotubes the “side-emission” geometry is superior to the more widely used “top-emission” geometry. Electrostatic potential distributions were calculated for some simplified models of the nanotubes, these calculations suggest that the enhanced field-emission of the “side-emission” geometry could be attributed to the increased corrugation and lowered potential barrier along the side of the corrugated nanotube compared with that along the top of the usual carbon nanotube.
Optimization of ridge height for the fabrication of high performance InGaAsN ridge waveguide lasers with pulsed anodic oxidation
Authors: Liu C. Y. , Qu Y. , Yuan Shu , Yoon S. F.
Published: November 2004

The dependence of the ridge height on the performance of the ridge waveguide (RWG) lasers has been systematically studied. It was found that the optimum ridge height corresponds to an etching depth where all the p-doped layers above the active region were removed. InGaAsN triple-quantum-well RWG lasers with optimized ridge height were fabricated with pulsed anodic oxidation. The lowest threshold current density (Jth) of 711A∕cm2 was obtained from a 10×1300μm2 InGaAsN RWG laser. The corresponding transparency current density (Jtr) of the fabricated InGaAsN RWG lasers was 438A∕cm2 (equivalent to 146A∕cm2 per well).
Characterization of single magnetic particles with InAs quantum-well Hall devices
Authors: Landry G. , Miller M. M. , Bennett B. R. , Johnson M. , Smolyaninova V.
Published: November 2004

We have measured the magnetic dipolar field from individual micron-sized spherical ferromagnetic particles. The particles were positioned using an atomic force microscope and measured using submicron Hall sensors fabricated from an InAs single-quantum-well heterostructure with lateral dimensions of 0.5–2.5μm. The magnetic moment of individual particles has been measured, verifying their dipolar moment. We also demonstrate a scaling rule for the detection of individual particles which is relevant to the design of biosensors.
Yellow dwarf of tobacco in Australia. V. Transmission by Orosius argentatus (Evans) to some alternative host plants.
Authors: Helson GAH
Published: November 2004

Tobacco yellow dwarf virus disease was experimentally transmitted to 15 species of plants by the leafhopper, Orosius argentatus (Evans). Eight of these plants are summer annuals and seven are autumn-spring growing plants which provide a continuous succession and wide range of hosts. Their occurrence in the districts where tobacco is grown makes control by the elimination of alternative host plants appear impracticable.
A theory of prior streams as a casual factor of soil occurrence in the riverine plain of South-Eastern Australia
Authors: Butler BW
Published: November 2004

A new theory is submitted on the origin of the soil formations in the alluvial plains region of southern New South Wales and Victoria embracing the Murray River and tributaries which has been given the name of the Riverine Plain of South-Eastern Australia. The Riverine Plain is delineated and the climate and physiography of the environment are briefly described. The theory postulates the occurrence of a system of prior streams independent of the present stream pattern; from the activity of this system the present soils and land surface were derived. The formations are discussed in terms of sedimentary array, salinity, and degree of leaching. Figures illustrate the ideal sediment pattern of a prior stream formation, a typical alluvial fan, and a simplified map of the region showing prior and present stream systems. A classification of the named soils from local soil surveys is given in the form of 15 sequences of general catenary relationship. The influence of halomorphism in soil development is discussed with the deduction that solonetzous and solodous soils occur generally throughout the region. The age of prior stream activity is set at late Pleistocene to early Recent.
Seasonal changes in spermatogenesis in rams : Their relation to plane of nutrition and to vitamin A status
Authors: Sapsford CS
Published: November 2004

Observations have been made on the seminal characters, body weights, and plasma vitamin A status of rams fed on carotene-deficient diets, at higher and lower levels of food intake. Carotene supplements were provided for a number of the rams at each level of dietary intake. The seminal characters exhibited a seasonal variation, characterized by a reduction in the total number and longevity of spermatozoa during the summer months. Within this period, a temporary increase in the number of morphologically abnormal spermatozoa occurred in the rams of low plasma vitamin A status, or on the lower plane of nutrition. Plasma vitamin A levels fell more rapidly in the rams on the higher plane of nutrition than in those on the lower plane. Morphological abnormality of spermatozoa attributed to vitamin A deficiency appeared at an earlier date in the high-plane group except when rams with presumably low liver stores of vitamin A were fed on the deficient diets. Vitamin A deficiency, if sufficiently severe, resulted in the appearance of a high percentage of morphologically abnormal spermatozoa in the semen of rams on both planes of nutrition. The addition of pure carotene to the diet prevented or reduced this degree of abnormality.
Anthracnose and seedling blight of Bathurst Burr caused by Colletotrichum xanthii Halst
Authors: Butler FC
Published: November 2004

In the summer rainfall regions of New South Wales during the past three seasons, a disease caused by the fungus, Colletotrichum xanthii, has caused widespread destruction of Bathurst burr, which ranks as one of the most serious weeds of pasture land in these areas. The disease, previously unrecorded in this State, was first observed on the Central Tableland but has since become established throughout the North-western and Central Western Slopes and Plains. It appears to be restricted to the genus Xanthium and is characterized by anthracnose-type stem lesions which tend to produce a 'ring-bark' effect. A seedling blight condition may also occur. The disease carries over from season to season on old burr remains. Since 1947-48 it has occurred naturally in 50 different districts of the State. During 1949-50 it was artificially established in 16 districts where it had not been observed previously. Disease development is favoured by prolonged periods of wet weather in the summer and autumn. It is difficult on the basis of three seasons' observations to assess the economic value of the disease as a means of biologically controlling Bathurst burr. During these three seasons, however, it has largely removed the necessity for weedicide spraying and hand cutting of burrs on many properties in northern New South Wales and thereby proved to be the most useful parasitic disease of a weed host ever encountered in this State.
A study of the effect of Chrysomela hyperici Forst. on St. John's Wort in the Mannus Valley, NSW
Authors: Clark LR , Clark N
Published: November 2004

Conditions in those parts of the Mannus Valley, N.S.W., where Chrysomela hyperici Forst. has been liberated appear either unfavourable or just tolerable to the species, which has increased in numbers and spread to a limited extent in the more favourable parts of the area infested with St. John's wort. In the colony site studied intensively, the gradual multiplication of C. hyperici led to great destruction of the weed in places, but this destruction was soon followed by regeneration. Because of this and the way in which the beetles aggregate and move on definite fronts, there has been a history of waves of insects passing back and forth over a small area around the liberation site followed by waves of regeneration of the host plant. Very young and large old crowns of Hypericum were readily destroyed by the insect, but the mortality of mature crowns of moderate size was relatively low. Where few crowns were killed, vegetative reproduction soon resulted in the reoccupation of vacant spaces. Under some conditions, defoliation by the insect appeared to stimulate suckering and thereby produced a stand of higher crown density than the original one. This addition of new crowns must have rejuvenated some stands, and probably increased their resistance to further beetle attacks for a short time. The ability of St. John's wort to maintain its position of predominance in the community in the face of heavy insect damage was due partly to the absence of effective plant competitors. The heavy grazing by rabbits and kangaroos on the plants associated with the weed, and their habit of removing the ground cover by scratching, favoured the regeneration of Hypericum from seed in places where most of the original wort plants had been destroyed.
The epidemiology of parasitic gastro-enteritis of cattle
Authors: Roberts FHS , O'Sullivan PJ , Riek RF
Published: November 2004

Observations on parasitic gastro-enteritis of cattle are recorded with particular reference to its epidemiology under conditions existing in Queensland. The most important species of nematodes associated with this disease are Haemonchus contortus, Bunostomum phlebotomum, Cooperia punctata, C. pectinata, and Bosicola radiatus. All of these are serious among dairy cattle, but only H. contortus, Bosicola radiatus, and rarely Bunostomum phlebotomum among beef cattle. Ostertagia ostertagi and Trichostrongylus urei are common, but occur in pathogenic numbers only occasionally. Strongyloides papillosus and Moniezia sp., probably M. benedeni, are also discussed. The incidence and prevalence of these parasites are recorded and also the age of the calf when infestation was first detected. Pathogenic infestations are for the most part confined to young cattle 3 to 24 months of age. In dairy cattle, the most susceptible age is from 4 to 12 months; in beef cattle, the majority of outbreaks occur a few months after weaning. Outbreaks are usually seen during the winter and early spring, although on occasion, losses may commence in the autumn and occur also in early summer. Seasonal fluctuations in the populations of these helminths were followed by means of regular faecal egg counts. It was usual for the egg count of each species to increase to a peak, then to decline fairly rapidly, and to remain on a low level during the remainder of the period the animals were under observation, i.e. up to 18 months of age. The ages at which these peaks occurred are recorded and their relationship to the season of birth of the host is discussed. The influence of temperature and rainfall on the prevalence of these helminths has been studied and some preliminary observations are recorded on the development and behaviour of their preparasitic stages in the dung pad. Evidence is brought forward to show that cattle develop a strong resistance to infestation during the first 18 months or so of life. In young animals this reaction depends on exposure to infestation and is somewhat specific in nature in so far as it may be manifested against one species, but populations of other species may continue to increase. Thus, most animals became resistant to infestation with Cooperia spp. at about five months of age, but not to H. contortus and the other species until several months later. This resistance is considered mainly responsible for the light infestations usual among adult cattle. It appears strongest against B. phlebotomum and weakest against H. contortus, which is the most common and prevalent species among adult animals. Outbreaks of parasitic gastro-enteritis are considered to occur under conditions of high larval prevalence and poor nutrition, when resistance against infestation fails to be effective.
An interpretation of the occurrence of diverse types of soils on basalt in Northern NSW and Queensland.
Authors: Teakle LJH
Published: November 2004

This study is confined to a consideration of the genesis of soil patterns formed on basalt in four districts in northern New South Wales and Queensland. The chief features of five distinct groups of soils — probably of great soil group status — recognized in these soil patterns are described. It is concluded that any interpretation based solely on the present climatic conditions is inadequate. It is submitted that, in the patterns described, the different soil groups represented commenced to form during different climatic eras, on a new basalt flow or on a new basalt surface exposed by erosion. In each case the newly initiated soil would be in conformity with the pedogenic environment of the era. For instance, under high rainfall the red soils would be initiated; under low rainfall the black soils would be expected to form. These soils tend to persist unless removed by erosion in spite of subsequent changes in the pedogenic environment. This points to the importance of the time factor in the form of past climatic eras and of geologic erosion in the development of these soil patterns. It is suggested that these pedogenic factors may be important in the development of many soil patterns.
Effects of skin coatings on the behaviour of apples in storage. I. Physiological and general investigations.
Authors: Trout SA , Hall EG , Sykes SM
Published: November 2004

The effects of skin coatings on the physiological behaviour of apples have been investigated and a mechanism for the effects has been suggested. Using mainly the variety Granny Smith, the composition of the internal atmosphere, respiration rate, and other changes associated with ripening have been studied in both uncoated and coated apples. The effects were found to depend greatly on temperature, thickness and type of coating, and variety and condition of the fruits. Coating increased the resistance of the skin to gaseous diffusion and thus greatly reduced the internal oxygen concentration, increased the internal carbon dioxide concentration, reduced the respiration rate, and retarded ripening changes by varying degrees. The most spectacular effect on ripening was a marked retardation of normal yellowing of the skin, which is mainly controlled by internal oxygen supply.
Effects of skin coatings on the behaviour of apples in storage. 2. Common storage investigations.
Authors: Hall EG , Sykes SM , Trout SA
Published: November 2004

Apples of several varieties, particularly Granny Smith, were held in common (unrefrigerated) storage after treatment with skin coatings. Under favourable conditions their storage life was increased by about 50 per cent., the greatest increase being with early varieties. Undesirable side effects are described and their relation to storage conditions discussed. The most important factors influencing the storage behaviour of coated apples were temperature and maturity. Temperatures above 70°F, even for comparatively short periods, led to fermentation and alcoholic breakdown. Fruit picked at the optimum stage for cool storage held best after coating; picked either before or after this stage, it developed disorders in storage. The best coating tested was an 8-10 per cent. alcoholic solution of 2 parts of castor oil and 1 part of wax-free shellac (C.O.S.). It was satisfactory with most varieties in cool conditions, but sometimes caused slight spotting at the lenticels. Emulsions of medicinal-grade paraffin oil, alone or mixed with castor oil, were satisfactory on most varieties (e.g. Granny Smith) which develop a copious natural waxy coating. Waxes were also applied as emulsions; the best was a mixture of 2 or 3 parts of paraffin wax with 1 part of carnauba or lac wax. Emulsion coatings were generally improved by adding 25 per cent. of wax-free shellac in 3 per cent. ammonia. C.O.S. was more effective than oil coatings and both were more effective than waxes in retarding ripening and in controlling disorders of senescence. Waxes reduced shrivelling much more than the other coatings. All coatings controlled Jonathan spot and greatly reduced bitter pit. Only the alcoholic solutions reduced mould, which was often increased by emulsions.
Studies on resistance of sheep to infestation with Haemonchus contortus and Trichostrongylus spp. and on the immunological reactions of sheep exposed to infestation. VI. The influence of age and nutrition on resistance to Trichostrongylus colubriformis.
Authors: Stewart DF , Gordon HMcL
Published: November 2004

Of 10 sheep aged 3-4 years which had been born and maintained under worm-free conditions, 7 died from an initial experimental infestation with Trichostrongylus colubriformis. This mortality was in striking contrast to the results with nine-months-old sheep which had had previous experience of infestation. It demonstrated that resistance to T. colubriformis could not be ascribed to increasing age. In a group fed on a low plane of nutrition and given 40,000 or 100,000 T. colubriformis larvae, more sheep developed infestations than did similar sheep in groups given an adequate or a high-protein diet. in lambs which had been kept worm-free since birth and then dosed with 20,000 T. colubriformis larvae, infestation developed almost equally in those fed on the poor diet and those fed on the high-protein diet. The groups fed on the low plane of nutrition successfully withstood subsequent challenge doses of up to 300,000 T. colubriformis larvae. In these experiments, previous exposure to infestation apparently exercised more influence on resistance than did diet.
Preliminary investigations into the life cycle of Ventruia inaequalis (Cooke) WINT. in South Australia.
Authors: Jeffery MW
Published: November 2004

Investigation into the possible sources of primary infection by the fungus Ventruia inaequalis (Cooke) Wint. in spring has been carried out. The results present new information on the life cycle of the pathogen under South Australian conditions. Sources of primary infection, such 'as lesions on one-year-old wood or overwintering superficial conidia on the trees, do not appear important. Bud-scale infection of dormant buds has been shown, and its relative importance is discussed. Ascospores are the most important source of primary infection. Their period of discharge extends to a later date than previously reported for South Australia and is considered in relation to leader shoot and late summer spot infection.
Studies in fleece-rot of sheep.
Authors: Hayman RH
Published: November 2004

Occasions of unduly heavy and prolonged rainfall during the period April 1946 – July 1951 resulted in the occurrence of fleece-rot in sheep of the Field Station flock in each of the six years. Data obtained from periodic examinations of the flock have been related to the nature of climatic conditions associated with outbreaks of the disease. They show that when rain occurs in falls of sufficient intensity and frequency to wet sheep to the skin for a period of a week or more, fleece-rot may be expected to develop in some of them. The longer the period for which the sheep are kept wet, the greater the number in a flock which will be affected. Fleece-rot was experimentally induced in four out of five Merino sheep known to be susceptible to the condition, whereas five animals known to be resistant were unaffected by the same treatment. Microscopic examination of skin sections taken from naturally occurring cases revealed the presence of a dermatitis. A similar condition was observed in skin sections from the animals in which fleece-rot was experimentally induced. Young sheep were found to be more susceptible than old. There was no association between degree of wrinkling and susceptibility or between 'grip' and susceptibility. When subjectively-appraised attributes of the fleece were related to the occurrence of fleece-rot, confusing results were obtained. However, when measured fleece data, obtained from a group of Merino sheep which had been under observation for four consecutive years, were considered, it was found that those for clean-scoured yield, wax and suint ratio, and density of fibre population per unit area of skin surface, were related to resistance or susceptibility. Nevertheless, a number of animals were found which were susceptible or resistant to the disease despite the nature of their fleece attributes. Differences in susceptibility were found between families of Merino sheep. These are associated with between-family differences for the fleece attributes found to be important in fleece-rot reaction.
Strain reaction to potassium deficiency in subterranean clover (Trifolium subterraneum L.).
Authors: Rossiter RC
Published: November 2004

The results of three experiments — two in pot culture and one in the field — are described in which five commercial strains of subterranean clover (Trifolium subterraneum L.) were grown on Crawley sand at Perth. The strains were Dwalganup, Yarloop, Bacchus Marsh, Mt. Barker, and Tallarook. All strains were affected similarly by potassium deficiency and no evidence of differential response to applied potassium was obtained, either in dry matter yield or potassium content. As an aid in the diagnosis of potassium deficiency, the value 0.8 per cent. potassium in the leaf plus petiole of clover tops (irrespective of strain) sampled 10 weeks or more after germination may be taken to indicate incipient deficiency.
Development of the secondary follicle population in sheep.
Authors: Short BF
Published: November 2004

The maturation of the secondary follicle population from birth to 6 months is traced by comparing the ratio of mature fibre-producing secondary to primary follicles at successive ages, with the ratio at birth of all secondary follicles, mature and immature, to primary follicles. In lambs of various sheep types all secondary follicles were present at birth. The rate at which secondary follicles mature reaches a maximum at 7-21 days after birth, with some 65.0 per cent. of secondaries growing fibres by 28 days. The evidence indicates that the adult secondary follicle population may be permanently affected in two ways. Firstly, the number of secondary follicles initiated up to the time of birth may be restricted by adverse foetal environments. Secondly, the number of initiated secondary follicles which mature may be restricted by the early post-natal environment, particularly up to 21 days.
Buffer systems in the rumen of sheep. II. Buffering properties in relationship to composition.
Authors: Turner AW , Hodgetts VE
Published: November 2004

Acid-base titration curves of ovine ruminal fluid confirmed the findings of Clark and Lombard (1951) that ruminal fluid is relatively well buffered against addition of acid, but relatively poorly against additions of alkali. However, considerable differences were observed between samples from different sheep. These were associated with differences in the interval after feeding, the nature of the diet, and the consumption of drinking water; and were correlated with differences in total and relative concentrations of bicarbonate, phosphate, and volatile fatty acids (VFA). The relative importance of the main buffering components in particular fluids was studied by examining the effects of the following procedures upon titration curves: ( a ) varying bicarbonate concentration by varying pCO2; ( b ) removing, and restoring, bicarbonate, phosphate, and VFA; and ( c ) removing particulate material. Particulate material was relatively unimportant as a buffer. Within the usual pH range of the rumen, the important buffering components were bicarbonate and phosphate. In the fasting rumen, bicarbonate was more important than phosphate, and this was found to be also true in parotid saliva. As ruminal fermentation proceeded and as VFA accumulated, bicarbonate and pH decreased and the buffer value depended more and more upon phosphate. In actively fermenting rumens, in which VFA concentration was high and the pH less than 6, VFA contributed significantly to the buffer resistance against further additions of acid. It is pointed out that, because the acids and bases generated during ruminal fermentation are relatively weak, they alter ruminal pH less, mole for mole, than the strong titrants conventionally used in titrations.
The influence of depth of sowing and temperature on pre-emergence weight changes in Subterranean clover (Trifolium subterraneum L.).
Authors: Black JN
Published: November 2004

The pre-emergence weight changes in subterranean clover (Trifolium subterraneum L. var. Bacchus Marsh) were measured at temperatures of 28, 21, 14, and 7°C. Plants were sown in washed sand at four depths, ½, 1, 1½ and 2 in., and daily determinations of plant weight and of the weight of cotyledon, hypocotyl, and root fractions were made until emergence from each depth took place. No differences could be detected in total plant weight or in the proportions of the constituent parts on any one day between plants sown at the various depths under a particular temperature treatment. The rate of transfer of material from the cotyledons to the rest of the plant increases with temperature, this increase being progressively reduced with each rise in temperature. The extent of cotyledonary reserves remaining on emergence was found to be significantly affected by both temperature and depth of sowing, being greatest at 1/2 in. and diminishing with depth. The optimal temperature for hypocotyl extension per unit of cotyledonary material translocated was 21°C. Cotyledon weight on emergence expressed as a percentage of total plant weight varied from 33 to 61, and appears to be markedly less than those reported for other species.
Flower initiation in pasture legumes. II. Geographical implications of cold temperature requirements of varieties of Trifolium subterraneum L.
Authors: Aitken Y
Published: November 2004

In Trifolium subterraneum L. (subterranean clover) the low temperature requirements of its range of varieties, together with the mild winter of southern Australia, result in a lengthened growing season compared with that usual in northern Europe, and hence in greater productivity. Over much of southern Australia, some degree of summer drought prevents the use or reduces the yield of perennial species and so the productive capacity of this particular clover has made it of major importance in pastures. The low temperature requirement, however, reduces the value of the species as a self-regenerating annual where temperatures of both summer and winter seasons are too high for flower initiation. This occurs with the later varieties when sown in northern Australia. Temperatures of the summer growing season in the tropics are likely to be too high even for the short low temperature requirement of the earliest flowering group, with its high critical upper margin of about 75°F mean weekly temperature. The dry winter months are cooler, and, if water supply is available, flower initiation is possible, though retarded with consequent leafiness of the plant. Hence in northern Australia, only varieties in the early flowering group may be of use in pastures, and then only in the cooler parts of the region.
Non-symbiotic nitrogen-fixing bacteria in soil. II. Studies on Azotobacter.
Authors: Parker CA
Published: November 2004

Forty-two soils from the Western Australian wheat belt were examined for the presence of Azotobacter by microscopic examination of enrichment cultures, and by plate identification on three different selective agar media. Judged microscopically, most of the soils appeared to contain Azotobacter; culturally, distribution was sporadic and varied greatly according to the medium used. Distribution was not correlated with soil type. Colony production on the selective media was not improved by the addition of straw extracts, amino acids, or vitamins, or when the plates were incubated at lowered oxygen partial pressures. A freshly isolated strain of A. chroococcum fixed nitrogen more efficiently when grown in association with another soil bacterium; in pure culture it showed adaptation to a nitrogen-free medium. Viable counts on different agar media with different treatments indicated the presence in one medium of an inhibitor which greatly reduced the number of colonies formed. It is concluded that nitrogen-free selective media may give an unreliable estimate of the distribution of Azotobacter in soils.
Developmental modification of fleece structure by adverse maternal nutrition
Authors: Short BF
Published: November 2004

As part of a series of investigations on the factors influencing the development of the secondary follicle population during foetal and early post-natal life of lambs, the influence of severe restriction of the feed intake of ewes throughout pregnancy is recorded. Adverse maternal nutrition reduced the body weight and secondary: primary (S/P) fibre ratio of lambs a t birth but had little effect on the S/P follicle ratio. Although the post-partum feeding of ewes was ad libitum, the restricted nutritional regime during gestation had a delayed impact on the post-natal growth of lambs, presumably due to a reduced milk production; this resulted in restricted final S/P ratios and number of fibres per unit area of skin in the offspring of the poorly fed ewes. At 200 days of age, the offspring of ewes well fed and poorly fed during gestation had attained the same mean body weights and had produced the same amount of clean wool per head and per unit area of skin. Lambs with fewer mature follicles per unit area of skin grew fibres both longer and coarser than lambs with higher fibre densities. This evidence supports previous observations that wool production per unit area of skin is independent of fibre density, and further substantiates the hypothesis of competition between follicles for the precursors of wool keratin.
Copper-molybdenum-sulphate interaction in induction of Ovine hypocupraemia and hypocuprosis
Authors: Wynne KN , McClymont GL
Published: November 2004

A basal diet containing 6.2 p.p.m. copper, 0.8 p.p.m. molybdenum, and 0.04 per cent. inorganic sulphate was fed unsupplenlented to one group of sheep. Four other groups were fed on the same diet supplemented with ammonium molybdate to give a molybdenum content of 5.1 p.p.m. or with sodium sulphate to give an inorganic sulphate content of 0.40 per cent., or with both. Sheep on the unsupplemented basal diet showed no marked disturbance of their liver and blood copper concentrations. Sheep maintained for 50 weeks on the diet containing both molybdenum and sulphate supplements showed a progressive fall in liver and blood copper levels, and developed dystrophic wool and hypochromatrichia. On a restricted feed intake of the same diet, sheep displayed a similar fall in liver copper and similar wool changes, but maintained a normal blood copper level for a longer period before developing hypocupraemia. Hypochromatrichia appeared to develop in this group before hypocupraemia was evident. With only the sulphate supplement added to the basal diet, liver copper concentrations fell, but not to a level associated with hypocupraemia. With only the molybdenum supplement added to the basal diet, copper retention by the liver was depressed to a small, but significant extent compared with the controls. The diet of the groups showing evidence of hypocuprosis approximately reproduced the mean copper, molybdenum, and sulphate status of the feed in an area in New South Wales enzootically affected with hypocuprosis. It is concluded that hypocuprosis in this area at least is explicable in terms of copper-molybdenum-sulphate interaction.
Fleece growth of young Lincoln, Corriedale, Polwarth, and fine Merino maiden ewes grazed on an unimproved paspalum pasture
Authors: Daly RA , Carter HB
Published: November 2004

Two young maiden ewes of each of the Lincoln, Corriedale, Polwarth, and fine Merino breeds were kept together on 3 acres of unimproved paspalum dominant pasture at Castle Hill, near Sydney, for 42 weeks. In this time 44½ in. of rain were recorded, with fairly uniform monthly incidence. The response of the sheep to these conditions was studied and compared with that of similar sheep which were kept in housed, single pens and fed unrestricted quantities of a high-quality diet (Daly and Carter 1955). Liveweight and wool production of the field sheep were dependent on seasonal trends in pasture quality and were consistently lower than for the housed, well-fed sheep. Rain removed appreciable quantities of wax and suint from the fleeces of Lincolns, Corriedales, and Polwarths and altered the pattern of distribution of these components in them. In warm, wet conditions "canary stain" and bacterial discoloration became conspicuous in Corriedale and Polwarth fleeces but not in Lincoln and fine Merino fleeces. In all respects the fine Merino fleeces were least affected by the relatively severe climatic conditions.
Some aspects of gene dosage in N- type sheep
Authors: Stephenson SK
Published: November 2004

The dominant and recessive mimic genes N and nr produce increased birthcoat hairiness in New Zealand Romney lambs. This hairiness has been studied in lambs of different genotypes by three different methods. It has been found: (i) that in individual lambs there is a gradient in hairiness from the shoulder patch to the britch; (ii) increases in hairiness with increasing dosage of the N and nr genes conform to this gradient; (iii) with any single increase in N-gene dosage there is a differential rate of increase in hairiness on different positions. These results are explained on the hypothesis that the primary gene action is linear, but the gradient is modified by a threshold and possibly by a ceiling effect in the production of birthcoat medullation.
An experimental study of heat tolerance of cattle
Authors: Dowling DF
Published: November 2004

The ability of cattle to maintain a normal body temperature in a dry, hot, inland Australian environment is associated with their ability to dissipate excess heat from the body.
A heat tolerance test, based on rectal temperature responses after exercise, is reported. This test indicates the animal's capacity to lose heat. Forty animals, classified on their coat covering, were included in the experiments described. The differences in coat covering are described and associated with differences in rectal temperature under various forms of heat stress. The results serve to illustrate the basic weaknesses of any field test (or hot-room test) which cannot be carried out under conditions where major factors influencing the "adaptability" and type of coat can be kept uniform for all animals tested.
Sweat glands in Zebu (Bos indicus L.) and European (B. taurus L.) cattle. I. Size of individual glands, the denseness of their population, and their depth below the skin surface
Authors: Nay T , Hayman RH
Published: November 2004

Number of sweat glands per unit area of skin, their size, and their depth below the epidermis were compared in skin biopsy specimens obtained from the midside region of two Zebu and three European breeds of dairy cattle. Within Zebu breeds, comparisons were made between sweat glands from the midside and the dewlap. Zebus were found to have much larger and more numerous sweat glands than European animals. Within Zebus, sweat glands were slightly larger, and much more numerous, on the midside than on the dewlap. They are much closer to the skin surface in Zebu cattle than in European. In Zebus sweat glands are longer and of greater diameter than in European cattle. In appearance they are sac-like, with few convolutions, whereas sweat glands in European cattle are rarely sac-like, and quite convoluted.
The early vegetative growth of three strains of subterranean clover (Trifolium subterraneum L.) in relation to size of seed
Authors: Black JN
Published: November 2004

Three strains of subterranean clover (Bacchus Marsh, Clare, and Mount Barker) were grown in pot culture at the Waite Agricultural Research Institute; for each strain, seed of four widely separated sizes mere sown. Dry weight a t any one time in the early vegetative stage was linearly related to embryo weight, but was independent of strain. Hence differences in early growth noted under uniform environmental conditions between strains are the result not of differing relative growth rates, but of differences in the size distribution within the seed populations; evidence is presented suggesting that there may well be little difference in the size distribution of seed of Bacchus Marsh and Mt. Barker, but that Clare contains a higher proportion of large seed, and thus as a strain would be expected to give greater early production. Leaf area per plant was also linearly related to embryo weight but independent of strain; but for a common embryo weight, Clare was found to have fewer leaves than the other two strains. Examination of the areas of successive leaves showed that the maintenance of similar total leaf areas depended on a balance of rate of leaf production and size of individual leaves; in relation to Bacchus Marsh and Mt. Barker, Clare has fewer but large1 leaves.
Studies on the sultana vine. V. Further studies on the course of bud burst with reference to time of pruning
Authors: Antcliff AJ , Webster WJ , May P
Published: November 2004

Further studies on the course of bud burst were made on three sites in the Sunraysia district and the effect of three times of pruning on time of bursting investigated over a period of three seasons. The largest differences in time of bursting were between seasons, with smaller differences between sites and an interaction between sites and seasons. Vines pruned on August 11 burst about 3 days later than vines pruned on June 4 or July 8. The June-pruned vines burst earlier than the July-pruned vines at bud positions 13 and 14 only. The trends of the bud position means for time of bursting, bud burst, and fruitful shoots on the one site on heavy soil differed from the other two sites on sandy soils which were very similar. The three sets of deviations appeared to be related. Data obtained on the proportion of buds producing two shoots suggested that this was positively related to nitrogen.