Two species of ants, Formica obscuripes Forel and Dolichoderus (Hypoclinea) taschenbergi (Mayr), attended species of Cinara, mainly C. gracilis (Wilson) on Pinus banksiana Lamb., in the Sandilands Forest Reserve, Man. The aphids occurred only on trees near ant hills. Removing the aphids by spraying had no serious effect on the ants. Destruction of an ant colony was followed by the disappearance of the aphids. The trees benefited through removal of defoliating insects by the ants.

Systematic Mn K-edge x-ray absorption spectroscopy (XAS) measurements on samples of La1-xSrxMnO3, which are precursors to colossal magnetoresistive (CMR) materials, are reported. Detailed results on the edge or chemical shift as a function of Sr concentration (hole doping) and sample preparation (air vs oxygen annealed), are discussed. For comparison, a systematic XANES study of the Mn K-edge energy shift, denoting valence change in Mn, has been made in standard manganese oxide systems. Contrary to expectations, the variation in near-edge energies for Mn in La0.725Sr0.275MnO3 were small when compared to the difference between that for manganese oxide standards of nominal valence of +3 and +4 (Mn2O3 and MnO2).

Time-resolved in situ neutron powder diffraction and Rietveld refinement have been used to study the synthesis of Bi-2212 from hydroxide precursors in a 2% O2 atmosphere. Bi-2212 was found to form within the temperature range 770–800 °C. Studies at 800 °C show that Bi-2212 grows rapidly at the expense of Bi-2201. Upon lowering the temperature to 500 °C and changing the atmosphere to Ar, a rapid increase in the lattice parameters was observed. We attribute this change to the loss of oxygen from the Bi-2212 lattice. The final material exhibited a Tc of 94 K.

We report the results of temperature dependent, Mn K-edge X-ray Absorption measurements: Magnetic X-ray Circular Dichroism (MXCD) for local magnetic properties and X-ray Absorption Near Edge (XANES) for electronic and structural properties of Mn-based oxide magnetoresistive compounds La1−xSrxMnO3. This is the first report of an MXCD signal of the Mn K-edge in Mn oxide systems. By studying the integrated peak intensity of the first peak in the MXCD signal, it can be determined that the magnetic properties of the system are independent of temperature in the range 94 to 223K.

Neutron powder diffraction studies of the layered compounds R1.2Sr1.8Mn2O7, (R = La,Pr, Nd), RSr2Mn2O7 (R = Pr,Nd),and La1.4Sr1.6Mn2O7 show that the degree of distortion of the MnO6 octahcdra do not correlate with the appearance of a metal-insulator (MI) transition in these compounds. Instead, the in-plane Mn-O bond length appears to be a better indicator of the electronic behavior. Detailed bulk magnetization studies on single crystal La1.2Sr1.8Mn2O7 show thai there are three magnetic regimes as a function of temperature: paramagnetic insulator, short-range ordered (SRO) fcrrromangct, and long-range ordered (LRO) fcrromagnct. Scaling analysis indicates that a 2D finite-size XY model is an appropriate description of the magnetic state in the SRO regime.

The capabilities of the X-ray Timing Explorer (XTE) are described with particular attention paid to current scientific problems it will address from galactic neutron star systems to active galactic nuclei. It features a low-background continuous 2-200 keV response with large apertures (a 0.63-m2 proportional counter array and a 0.16-m2 dual rocking NaI/CsI scintillation array). Rapid response (in hours) to temporal phenomena, e.g. transients, is obtained by virtue of a scanning all-sky monitor and rapid maneuverability. XTE will carry out detailed energy-resolved studies of phenomena close to neutron stars (e.g. QPO’s) because of its sub-millisecond timing (to 10 μs), its high telemetry rates (to 256 kb/s), and the high throughput of its data system (to ≳ 2 × 105 c s−1).

We have determined the crystal structures of five phases in the Bal-xKxBiO3 system for 0≤x≤0.5 and 10K≤T≤473K. Superconductivity occurs only in a cubic perovskite phase with the maximum Tc at the transition to an orthorhombic, Ibmm, phase. The commensurate structure of this orthorhombic phase, which involves only tilting of the Bi06 octahedra, provides no explanation for its non-metallic behavior. However, an incommensurate structural modulation, observed by electron diffraction, may provide a rationalization. Thus, the maximum Tc at the phase boundary may result from competition between superconductivity and a charge density wave. Further studies of the phase diagram at high temperatures, where controlled oxygen atmospheres are required, reveal an unusual reentrant formation of a potassium-containing impurity phase which explains the need for synthesis techniques that involve initially reacting in a reducing atmosphere, followed by oxygenation at lower temperature.

Eu2.xCexCuO4±δ (0 ≤ x ≤ 0.17) has been synthesized with the tetragonal T’ structure. AC susceptibility and resistance measurements show that Eu2‐xCexCuO4±δ becomes superconducting with τc∼13 K for x= 0.15 and 0.17, when prepared under reducing conditions. The 151Eu Mossbauer shift shows that the Euvalence falls into a narrow range near Eu 3+ . The temperature dependence of the Mossbauer absorption yields a Debye temperature of 319 K for the Eu ion in Eu1.85Ce0.15CuO4±δ

We have studied mixed-phase samples of bulk LazCuO4 using neutron powder diffraction, thermogravimetric analysis and resistivity measurements. Samples fired at 950°C and slowly cooled form in the K2NiF4 structure with CuO impurities for z<2 and La2O3 impurities for z>2. Neither La-vacancies nor stacking defects were found. The bulk resistivity of the samples show semiconducting behavior which is shorted at 38K by small amounts of superconducting material. The superconductivity is due to the presence of an oxygen-rich phase with stoichiometry La2CuO4.08. The occurrence of superconductivity in pure La2CuO4.08 with the same Tc as observed in the doped La1.85 Sr0.15CuO4 indicates that the excess oxygen provides the same level of doping as metal-ion substitution.

Superconducting Ba0.6K0.4BiO3, with a Tc of 30K, shows a large 18O isotope effect which indicates that phonons are involved in the pairing mechanism. Infrared reflectivity measurements indicate a value for the superconducting gap consistent with moderate coupling (2Δ/kTc = 3.5 ± 0.5). A mediating energy for pairing of about 40 meV would be required to obtain a Tc of 30K. Strong coupling of electrons by optical phonons (which are present in this material with energies up to 80 meV) could account for the observed transition temperature. Recent tunneling spectroscopy shows the presence of strongly coupled optical phonons in the 40 to 70 meV region, indicating that superconductivity in this material may be phonon mediated.

We have investigated the structure and composition of La2CuO4 (both pure and Sr-doped) and Nd(Ba2−xNdx)Cu3O7 using powder neutron diffraction. In La2−xSrxCuO4, Tc reacnes its maximum at x=0.15, after which vacancies are introduced in the 2D planes and superconductivity is destroyed. Superconductivity in La2CuO4 is not bulk. No evidence for nonstoichlometry in this material can be observed. In the Nd(Ba2−xNdx)Cu3O7 system, Tc is a complex function of oxygen ordering and electronic effects.

The question of valence of Cu and rare-earth atoms in the newly discovered oxide superconductors with high transition temperatures is crucial to the understanding of their electronic structure. We have measured the X-Ray Absorption Near Edge Structure (XANES) of Cu K transition and Pr Ljjj transition to obtain information on the valence of Cu, and Pr in La2−xSrxCuO4 and Y1−xPrxBa2Cu3O7-δ. We will present the experimental results, compare them with calculations of absorption cross-section for model atomic clusters, and discuss the valence of Cu as a function of oxygen concentration.

Information relating to the carcass composition of grass-fattened beef cattle in the UK is not only limited in extent, but is also frequently uni-dimensional, in that the quantitative changes in carcass composition with time cannot be readily assessed. Furthermore, the methods used in selecting animals for slaughter (the visual appraisal of condition) introduces a source of non-random variation that cannot be removed with statistical confidence.

The primary objective of the analysis reported here, therefore, was to evaluate the effects of time on carcass composition and thereby provide information upon which objective production strategies could be based.

48 fattening steers and heifers (16-19 months old and 355 kg liveweight) of two contrasting breed types (Charolais x Hereford x Friesian and Hereford x Friesian) were summer grazed at a stocking rate of 5 animals per hectare. The animals were randomly allocated (at the start of the grazing season) to three slaughter points covering a 12 week period from early July to early October. The commercial saleable meat yield of the left side of each animal was measured together with compositional data from rib sample joints.

1. A total of sixty, 7-day-old British Friesian male calves, reared on a conventional early-weaning system, were used in two experiments in which dried skim milk was partially replaced by levels of 7, 14 and 21 % cooked potato flour (CPF). In the first experiment the diets were iso-energetic but differed in total nitrogen contents, whilst in the second experiment, casein was used to make the diets iso-nitrogenous.

2. In both experiments, diets containing CPF depressed growth rate from 4 to 18 days on treatment (11 to 25 days of age) and reduced the firmness of the faeces. These effects were correlated with the concentrations of CPF in the diets, live-weight gain being depressed by 20%, and the firmness of the faeces by 14%, for each 10 % inclusion of CPF. After 18 days on treatment (25 days of age) these effects became less pronounced.

3. The overall performance of calves to weaning (after 35 days on treatment) was similar on all diets. Daily live-weight gains from 4 to 56 days and 35 to 56 days did not differ between treatments. 4. It was concluded that whilst the inclusion of CPF in the diets of milk-fed calves was unlikely to have any permanent effect on the live weight of calves at 5 or 8 weeks of age its use in milk diets for calves of less than 3 weeks of age must be limited if loose faeces are to be avoided.

A Lasting tradition among the ancients marked Sicily as the birthplace and Tisias and Corax as inventors of the art of rhetoric: and in this tradition, legendary though it became, there is a stricter truth than in most of the stories related about the foundation of invented arts. We, with more elaborate historical views, shall still say of rhetoric that it was created at a certain epoch; and can still point to the Sicilians Tisias and Corax as its authors. Oratory, to be sure, has existed almost as long as speech. Its beginnings are prehistoric, and must in any case be imperceptible; and if by rhetorician we meant no more than one who uses speech with more than common effect, we might set the origin of rhetoric as far back as we chose, and could hardly bring it lower than the beginning of recorded literature. Indeed we are told that under the Antonine Emperors the eminent scholar Telephus of Pergamum wrote a book on Rhetoric in Homer, in which he illustrated from the Poet the whole contemporary system of the art down to the thirteen constitutions of Minucian; and in the same spirit the Venerable Bede, resenting the claim of the Greeks to have invented tropes and figures of speech, wrote a short work to show that they could all be found in Holy Scripture. But such inquiries, even when conducted less foolishly than by Telephus and less incompetently than by Bede, are irrelevant to the proper history of rhetoric. Let the practice of oratory have begun when it may, the first attempts known to us in Classical Antiquity to formulate a series of principles for the art of speech were made in the fifth century before Christ. These earliest systems were naturally very imperfect: they could not immediately be either comprehensive or well organized. But they were something that had not existed at all before: methodical principles for speaking. At the moment when these were first set out the art of rhetoric began.

The early handbooks of rhetoric compiled by Tisias and Corax and their successors seem to have been directed entirely at successful speaking in courts of law. This was the art that Strepsiades set out to learn in the Philosopher's Thinking-shop; this, Isocrates complains, was the only object of technical writers on rhetoric before his time; and Aristotle, when he wrote the chapter that stands first in hisRhetoric, made just the same complaint: τ⋯ς αὐτ⋯ς oὔσμς μεθ⋯δoυ περι τ⋯ δημηγoρικτ⋯ και δικανικ⋯ και καλλιoνoς και πoλιτικωτ⋯ραςτ⋯ς δημηγoρικ⋯ς πραγματειας oὔςηρ ἤ oὔσης ἤ τ⋯ς περι τ⋯ ςυναλλ⋯γματα, πει μ⋯ν ⋯κεινης oὐδ⋯ν λ⋯γoυγι, περι δ⋯ικ⋯ξεσθαι π⋯ντες πειρ⋯νται τεχνoλoγειν. The art as the Sophists practised it was by no means so limited in its application: many of them were accustomed to playing the parts of statesmen and diplomats as well as of educators; and the most notorious field for their powers of oratory was of course the lecture or ⋯πιδειξις. But the systems of rhetoric that they devised and taught did not cover their own practice; and forensic oratory, as well as seeming the most commonly necessary kind at that time, was also, it must be said, the easiest to reduce to rule. Gorgias, it is true, professed to teach a rhetoric of more extended application, by means of which his pupils would be able to produce conviction in any public assembly;* but we must conclude that this wider field was at least very imperfectly treated in all the technical systems of the time. Plato shortly describes the position thus:μ⋯λιστα μ⋯ν πως περι τ⋯ς δικας λ⋯γεται τε και γρ⋯φεται τ⋯χνῇ, λ⋯γεται δ⋯ και περι δημηγoριας ‧ ⋯π ι πλ⋯o≠ δ⋯ oκ⋯κoα.