Showing papers by "University of Dundee published in 1968"

On ideals of finite homoloǵical dimension in local rings

Abstract: In this paper I shall demonstrate certain algebraic properties of ideals of finite homological dimension in local rings.In the first section, I show that no non-zero ideal of finite homological dimension in a local ring can be of zero grade (this is stated by Auslander and Buchsbaum in the appendix to (l), but I cannot find a proof in the literature). Using this result, together with the complex defined by a matrix, which is described by Eagon and Northcott in (2), I prove that an ideal of homological dimension one in a local ring Q may always, for some integer n, be described as the set of determinants of matrices obtained by adjoining to a certain (n–l)× n matrix with elements in the maximal ideal of Q another row with elements arbitrarily chosen in Q. (This result was established in (3), under the additional condition that Q should be a domain.)

Mycorrhizal Endogone Species

Abstract: The genus Endogone has been amended to include nonsporocarpic types. One new species, E. mosseae, with both endocarpic and ectocarpic chlamydospores, and two new varieties with only ectocarpic chla...

A two-year comparison of hand and electric toothbrushes.

Abstract: A controlled study was carried out on 103 dentally-oriented university students to compare the effects of hand and electric toothbrushing. The study lasted two years. Subjects were examined at the beginning, and 3, 6, 12 and 24 months later. Oral debris and calculus formation were assessed by a modification of Greene and Vermillion's (1960) methods, and gingivitis and periodontitis by Russell's (1956) technique. Half of the subjects using the electric brushes and half of those using hand brushes were instructed how to brush; the others were not. No significant differences in oral debris or calculus formation, in gingivitis and periodontitis, or in gingival recession were found between any of the groups at any stage in the study. It is concluded that the electric brush is not superior to the hand brush when used by dentally-oriented young adults.

Properties, relationships and transmission of a strain of raspberry ringspot virus infecting raspberry cultivars immune to the common Scottish strain*

Abstract: SUMMARY Plants of Lloyd George and Seedling M raspberry (Rubus idaeus L.) were found in eastern Scotland infected with raspberry ringspot (RRV), a virus to which these varieties were previously considered immune. Most RRV isolates from affected plants caused milder symptoms in herbaceous test plants than did the type isolates of the common Scottish and English strains. In graft-transmission tests the Lloyd George strain of RRV infected all the raspberry cultivars tested, including those immune to the common Scottish strain. No consistent differences were found between isolates of the two strains in in vitro properties or serological behaviour. Both strains were transmitted in seed of Stellaria media and in soil containing Longidorus elongatus. Possible reasons why the new strain is uncommon in Scotland are discussed.

Purification, properties and transmission of parsnip yellow fleck, a semi-persistent, aphid-borne virus

Abstract: SUMMARY Parsnip yellow fleck virus (PYFV) is the commonest cause of virus-like symptoms in parsnip plants in Britain: it is sap-transmissible but systemically infects few species outside the Umbelliferae. It has isometric particles 29–31 mμ in diameter, a sedimentation coefficient of 167s, and loses infectivity in sap after dilution to 10-3-10-4, heating for 10 min at 57·5–65°C, or storage at room temperature for 4–7 days. Two isolates, from parsnip and Anthriscus sylvestris respectively, are only distantly serologically related. The aphid Cavariella aegopodii transmits PYFV in a semi-persistent manner from A. sylvestris but not from parsnip. Transmission by aphids apparently depends on the presence in A. sylvestris or other source plants of a second virus, anthriscus yellows (AYV), which is persistent in the vector and not manually transmissible. PYFV was therefore not transmitted by aphids from manually inoculated plants or from parsnip or other plants immune to AYV. In controlled experiments, C. aegopodii transmitted PYFV (both A. sylvestris and parsnip isolates) from chervil plants inoculated separately with PYFV and AYV, but not from plants inoculated only with PYFV.

The association of Xiphinema diversicaudatum (Micoletsky) with strawberry latent ringspot and arabis mosaic viruses in a raspberry plantation

Abstract: SUMMARY An outbreak of strawberry latent ringspot virus (SLRV) in a plantation of Mailing Jewel raspberry coincided with the greatest abundance of the nematode vector, Xiphinema diversicaudatum. Arabis mosaic virus (AMV) was not detected in the crop but was, together with SLRV, in many weed species present. AMV was transmitted through the seed of Poa annua, Capsella bursa-pastoris and Senecio vulgaris and SLRV through the seed of Mentha arvensis. X. diversicaudatum were more numerous within the rows than between them and vertical sampling showed that most occurred between 4 and 12 in depth in both locations. Monthly sampling showed that egg laying occurred from April to July; populations increased to a peak in late autumn but declined during the winter, resulting in about a twofold annual increase in numbers. Females, males and juveniles transmitted AMV and SLRV to cucumber seedlings, and in the absence of plants the nematode retained AMV for 112 days and SLRV for 84 days.

In vitro regulation of the lipolysis of adipose tissue.

Abstract: Three sites at which nucleosides regulate adipose tissue lipolysis are distinguished, one of which is stimulatory and the other two inhibitory.

A note on the homology of ideals ǵenerated by three elements in local rings

Abstract: In this note, I show that, if Q is a local ring and s an integer, 1 < s < codim Q, then there is an ideal As of Q, generated by three or fewer elements of Q, such thatand that, if Q is not regular, then there is an ideal B of Q, generated by three or fewer elements and of infinite homological dimension over Q.

An immunohistochemical study of the adrenal medulla of the ox. A comparison of antibodies against whole ox chromaffin granules and ox chromogranin A.

Abstract: The adrenal medulla of ox was studied by an indirect immunofluorescent technique using anti-ox chromaffin granule serum. The serum had a weak cross reaction with ox brain stem and splenic nerve. There was a species cross reaction with sheep, pig and horse. Immunoelectrophoresis showed five components in the serum against ox adrenal lysates. The whole adrenal medulla of ox was found to fluoresce by the immunofluorescent technique but not the cortex. The adrenals of sheep, pig and horse behaved similarly using the anti-ox serum. A serum prepared against ox chromogranin-A, the most abundant soluble protein of the chromaffin granules, was also used for immunofluorescence. Again both the adrenaline and noradrenaline storing cells fluoresced, but not the cortex.

Fine Structure of Colpoda steinii During Encystment and Excystment

Abstract: SYNOPSIS. The encystment and excystment of Colpoda steinii was examined by electron microscopy. Cellular organelles including cilia are retained in the cyst without any fundamental alteration in structure. During encystment, the cell becomes surrounded by 2 coats, the inner of which is the more substanial and regular and is about 1600 A or more thick. It is probably formed in the main from material contained in bodies which have no obvious structure and which may be seen in the cell during cyst formation. Discharging vacuoles containing sheet-like material, probably derived from ingested bacteria, are particularly visible during encystment but probably play no direct role in the formation of the main cyst coat. During excystment, this coat is eroded away and, when it becomes thin enough, the motile cell bursts its way out.

Phase diagram of the alloy system Hg3Te3-In2Te3

Abstract: The liquidus and solidus of the quasi-binary alloy system Hg3Te3-In2Te3 have been determined by differential thermal analysis. The phase diagram proposed is confirmed by x-ray powder diffraction analysis. Terminal solid solutions exist from Hg3Te3 to 19 mol.% In2Te3 and from In2Te3 to 86 mol.% In2Te3. Narrow regions of solid solution exist on either side of the compositions 375, 50 and 75 mol.% In2Te3. The maximum in the liquidus occurs at the 50% composition, where the melting is congruent.

Effects of benzyladenine on cotyledon metabolism and growth of peas.

Abstract: Application of benzyladenine to dry pea seed delayed the production of amylase and the concomitant breakdown of starch. The utilization of nitrogenous reserve food material was also delayed. Shoot growth was correlated with breakdown of reserve food.Benzyladenine given to one of the cotyledons did not affect the senescence of the other. Cotyledonary axillary shoots were released from apical dominance, but only those originating from the benzyladenine treated cotyledon continued to develop. The pattern of growth initiated by benzyladenine was not altered by gibberellic acid although this substance caused increased elongation of all growing shoots.

Thermal Convection in the Archaean Crust

Abstract: Two genetic models have been compared for a tectonic pattern typical of undisturbed remnants of Archaean crust. A model implying simple thermal convection in a granodioritic crustal layer is found to have advantages over the classic model assuming the gregarious batholiths of Rhodesia to be granite diapirs.

Mercury-tolerant Pyrenophora avenae in seed oats

Abstract: Samples of Scottish and Ulster seed oats were examined for the effectiveness of treatment with an organo-mercurial fungicide in controlling Pyrenophora avenae Ito & Kuribay, the cause of leaf spot Seedling infection was initiated by mycelium on the caryopsis which was little affected by fungicide treatment Superficial mycelium on the lemma and palea was of minor importance and was more readily eradicated Several samples from both regions did not respond to fungicide treatment, and in one sample disease incidence was increased This was attributed to the presence of mercury-tolerant strains of the fungus There were indications that micro-organisms antagonistic to P avenae might have an inhibitory effect on the pathogen both in non-treated and mercury-treated seed