Showing papers by "University of Stirling published in 1973"

Measurements of Complex Excitation Amplitudes in Electron-Helium Collisions by Angular Correlations Using a Coincidence Method

Abstract: Angular correlations were measured by delayed coincidences between electrons of incident energy about 80 eV scattered inelastically from helium and photons from excited $3^{1}P$ and $2^{1}P$ states. From the angular correlation in each case we deduce the ratio of the differential cross sections for exciting the magnetic sublevels of the excited state and the phase between the corresponding excitation amplitudes. We compare the atomic radiation patterns with those predicted by the Born approximation.

Studies on the skin of plaice (Pleuronectes platessa L.)

Abstract: Eighty-nine O-group plaice from a natural population were exposed at 15°C to heavy infection by Cryptocotyle lingua cercariae. Subsequently 45 fish were retained at 15°C, whilst 44 were held at 5°C. Both groups were sampled by killing individual fish at intervals of 6,18,42 h and daily thereafter up to 710 h. Entire fish were fixed immediately in formol saline, transversely sectioned and stained by H & E, PAS, PAS-diastase, JSDB 109, Picro-Mallory, Masson's trichrome, Gram-Weigert and Alcian blue. Histopathological observations showed: (a) epidermal lesions associated with encysted metacercariae in adjacent tissues; (b) myofibrillar necrosis associated with bacteria possibly introduced by the parasite; and (c) a reactive swelling of the intermuscular septa. The progressive development of the parasite cyst and host capsule is described. Development of both was markedly inhibited at the lower temperature, but the inflammatory response at either temperature was slight. This may be evidence of a long-standing host-parasite relationship which has evolved to an advanced state of adaptation on the part of the parasite and tolerance on the part of the host.

The histopathology of salmon tagging

Abstract: Histopathological studies were carried out on the pathogenesis of the lesion induced by the insertion of a light plastic identification tag, in salmon parr on the river North Esk, Scotland. The experiments were carried out at mean water temperature of 127deg;C, 8°C and 4°C. The inflammatory response was similar at each temperature, but the rate of its development was markedly inhibited at 4°C. The qualitative response at the lower temperature was also slightly different in that polymorphonuclear leukocytes appeared to play a slightly more dominant role and the connective tissue response, which in all cases outweighed myofibrillar regeneration was more cellular at that temperature. The tagging lesion provides a very suitable model for the study of short and long term inflammation in salmonids and studies on the modification of these defensive mechanisms by temperature.

Aspects of the reproductive biology of the sprat, Sprattus sprattus (L.) in inshore waters of the west coast of Scotland

Abstract: Aspects of the reproductive biology of the sprat in inshore waters of the west coast of Scotland were investigated from August 1970 to July 1972. Spawning in sprat lasts for a period of five to six months, starting in February-March. Minimum size of maturity is 88–90 mm in both sexes but males tend to mature earlier in the season. Sprat shed their eggs in 7–10 batches. There is generally a higher proportion of females in the population. The fecundity ranges from 8700 to 46,600 in fish between 95 and 146 mm in length. It is significantly correlated to weight, length and age.

Food and feeding habits of the herring Clupea harengus and the sprat C. sprattus in inshore waters of the west coast of Scotland

Abstract: The food and feeding habits of the herring Clupea harengus L. and the sprat C. sprattus (L.) as 0-group and older fish in inshore waters of the west coast of Scotland, were studied from April, 1970 to March, 1972. The two species occurred together. The diets of 0-group herring and sprats are almost identical, both qualitatively and quantitatively. Their daily feeding rhythms also coincide. It is probable that competition between these two species in their first year of life could occur if the food supply is limiting. Changes in diet between 0-group and older fish are more pronounced in herring than in sprats. The diet itself is mainly crustacean in both clupeids, with copepods contributing the major share.

Resonance structure in the excitation cross section by electron impact of the 2s state in atomic hydrogen

Abstract: The cross section for excitation of atomic hydrogen to the $2s$ state by electron impact has been remeasured in a crossed-beam experiment in the energy range from threshold to 12.3 eV. An electron monochromator of the cylindrical type with a full width at half-maximum of 110 meV has been used. The $2s$ atoms were detected by quenching in an electrostatic field and observing the emitted Lyman-$\ensuremath{\alpha}$ photons. Absolute values for the cross section were obtained by normalizing to the close-coupling calculations of Burke et al. at 10.8 eV. Resonance structure at 11.7 eV, which is a superposition of the $^{1}S$ and $^{3}P$ resonances predicted by theory, has been detected. There is good agreement between the present experiment and the experiment by Oed.

Sealing device for prevention of leakage between cylindrical surfaces

Abstract: A sealing device for a shaft or cylinder to prevent axial leakage at high pressure comprises a groove in which a sealing ring is contained. The sealing ring is a compound element having a deformable O ring in the bottom of the groove and a metal ring nearly the axial length of the groove in contact with the O ring and faced with a polymer ring to contact the cylindrical surface. Gas under pressure enters the groove to hold the assembly toward the axial groove surface on the lower pressure side.

Feature-Testing Models and Their Application to Perception and Memory for Speech:

Abstract: Four models of the organization of feature-testing units in the perception of phonemes are developed and tested against data drawn from a number of published studies. The independence model, which asserts that features are tested independently of each other, is conclusively rejected. The response-conditional and stimulus-conditional models require individual feature-testing units to be dependent, respectively, on the responses of other feature-testing units and on the other features present in the stimulus. Both these models handle perceptual confusions very well among stop and nasal consonants, but are less satisfactory for fricatives. Finally, the correct-conditional model requires individual feature-testing units to be dependent on the correctness of the decisions made by other feature-testing units; this model is very poor for perceptual confusions but quite good for mnemonic confusions. In addition, some of the distinctive features currently favoured by linguists are shown to provide unsatisfactory d...

Internal combustion steam generating system

Abstract: An arrangement in which compressed air and fuel are intermixed and burned to release the energy in the fuel. The heat resulting from the combustion of fuel and compressed air is used to generate superheated steam. The superheated steam and products of combustion are intermixed within the combustion chamber, and the mixed gases are passed through a positive displacement motor and to a variable displacement motor which converts the energy in the gases into mechanical energy. A valve between the positive displacement motor and the second motor may be used to interrupt the mechanical output of the second motor, while retaining the gases within the combustion chamber in ready state for resuming the mechanical output upon subsequently displacing the valve to an open position.

Sealing means for the piston rod of a stirling engine

Abstract: In a Stirling Engine having a cylinder from which a piston rod extends is provided with a seal comprising a cylinder end wall member with a sequence of spaces about the rod including a labyrinth seal, a leakage gas return conduit coupled to said cylinder with a one way valve and an oil separation filter, and a pressure regulated oil filled space with the oil pressure controlled by the pressure in said conduit.

Management behaviour and a theory of diversification

Abstract: This paper investigates the basis for a behavioural theory of diversification. A theory of diversification may be required (i) for full analysis of competitive processes, which include innovation and cross-entry competition, and (ii) to understand the selection of diversification projects in individual firms. Alternative optimising and non-optimising models are feasible. The choice between these alternatives will be considered after the non-optimising model has been developed. Section I outlines the basic model and the general predictions which it generates. In section II the predictions are subjected to a coarse test, which is taken to justify further investigation of the model's properties. The model is developed more fully in section III.

Threshold electron energy-loss spectra for some unsaturated molecules

Abstract: Using a trochoidal electron monochromator/electron trap combination, we have recorded threshold electron energy-loss spectra for nitrogen, ethylene, propylene, but-1-ene, and cis - and trans -but-2-ene.

Calculating the economic benefits of soil survey

Abstract: Summary A farmer (or other users of land) achieves greatest net return by using each soil for the crop and management which gives maximum return. A soil map indicates the boundaries between soils requiring different management for optimum returns. The benefits from a soil survey increase with the ‘purity’ of the soil units as mapped. The cost of soil survey increases sharply with the ‘purity’ to be achieved. So it is necessary to recognize the stage beyond which the costs of yet more detailed soil survey are unlikely to exceed the benefits to be expected from mapping units of greater ‘purity’. This paper reports a simple algorithm for calculating the probable benefits from further soil survey to produce a map of higher ‘purity’ than so far achieved.

Changes in developing pea (Pisum sativum) seeds in relation to their ability to withstand desiccation

Abstract: SUMMARY In two separate experiments in 1970 and 1971 the germination ability of seeds that had been rapidly desiccated following harvesting from glasshouse-grown pea plants improved with time after fertilization. In 1970 the germination of seeds directly after harvesting also improved with time. In both years the readiness with which electrolytes were leached from dried seeds decreased with seed age, measured as time after fertilization. The germination ability of desiccated seeds, and of undried seeds in 1970, improved after the cessation of seed moisture increase on the parent plant. This improvement coincided, in 1970, with a fall in the readiness with which electrolytes could be leached from seeds and with a decline in the rate of oxygen uptake of seeds directly after harvest. Vital staining of dried seeds from harvest samples indicated the viability of the samples as determined by germination tests. In both years, when the cotyledons first showed complete staining, the staining was very intense; in 1970 this occurred in a harvest sample with a greater than 50% germination level, but in 1971 it occurred in a sample that showed incomplete staining in the embryo axis and less than 5 % germination. In 1971 the comparative rates of moisture loss from seeds, measured with a sensor element diffusion porometer, were very low at 25 days after fertilization, increased up to a peak at 35 days and fell to a rate at the final harvest (44 days) which was nearly three times faster than the initial rate. Thus, during the period of dehydration, after 37 days, the seeds were able to lose moisture. When seeds were allowed to lose moisture slowly after harvest, before being desiccated rapidly, their eventual condition as measured by leaching improved. Also, the faster the initial water loss preceding rapid desiccation the more readily were the dried seeds leached. It is suggested that seeds can only withstand rapid desiccation after the cessation of moisture increase and after some slow dehydration, which is accompanied by a slowing down in physiological activity.

Kinetic Isotope Effects in Proton-Transfer Reactions

Abstract: Kinetic isotope effects in general have now become an everyday tool of the mechanistic organic chemist, and this is particularly true of hydrogen isotope effects, partly because hydrogen is involved in so many reactions, and partly because such effects are much larger for hydrogen than for the isotopes of heavier atoms. It is interesting to note that the rate differences between hydrogen and deuterium compounds are sometimes so large that the use of deuterium compounds has been proposed as a practical expedient for slowing down harmful reactions, e.g., the deterioration of lubricants by oxidation.1 Since the publication of the first edition of this book a number of books and review articles have appeared on the general subject of kinetic isotope effects.2–5 The present chapter will therefore be confined almost entirely to isotope effects in proton-transfer reactions, though some reference will be made to the closely allied problem of reactions involving the transfer of hydrogen atoms, especially in connection with the tunnel effect. On the other hand, no reference will be made to the increasing use of secondary hydrogen isotope effects for obtaining information about neighbouring group participation, especially in solvolytic reactions,6 since these do not normally involve proton transfers. Even in the field of proton-transfer reactions only a selection of the available material has been covered.

Qualitative aspects of the evaluation and control of research and development projects

Abstract: Decisions in research and development are usually based on a variety of data inputs. Some of these will be concerned with the returns offered by projects in money terms. Others will relate to more qualitative aspects of research work such as, perhaps, the establishment of a base in a new area of technology or the achievement of a stronger market position. This paper describes and illustrates how checklists may be used to assemble qualitative data for purposes of decision. These were formulated in an industrial R & D laboratory and the illustrative examples in the text make reference to real projects. The checklists described are an integral part of a comprehensive system of project evaluation and control in R & D which includes an analysis of the financial implications using net present value or discounted cash flow rate of return of the project risk, analysis and sensitivity tests. The detail of this part of the scheme is conventional and is therefore omitted from the paper.

Device for governing the temperature of a heater head of a hot gas engine

Abstract: In a hot gas Stirling cycle engine, the heating temperature is controlled by a servo-governed system which selects optimum airfuel mixture from a blower driven by the engine thereby also compensating for variations of blower performance.