Showing papers by "University of Manchester published in 1975"

The quantitative analysis of thin specimens

Abstract: SUMMARY Results are reported concerning the use of an energy dispersive X-ray detector to carry out the analysis of thin foils in the electron microscope. The combination of a thin specimen and the extreme stability of the energy dispersive X-ray detector enables the experimental determination of a calibration curve of X-ray production—detection efficiency vs characteristic X-ray energy. Quantitative analysis can be carried out using the calibration curve without reference to standards at the time of analysis.

A clinicopathologic study of 92 cases of granulosa cell tumor of the ovary with special reference to the factors influencing prognosis.

Abstract: Ninety-two cases of granulosa cell tumor of the ovary have been studied. The clinical and pathologic data from this group were similar to that obtained in previous series. Because of the long natural history of many granulosa cell tumors, crude death rates over a relatively short period give little indication of the true malignant potential of these neoplasms and hence corrected survival rates were calculated; these show that, if no patient died from any other disease, approximately half of the women with this neoplasm would die, as a result of the tumor, within 20 years. Factors indicating a relatively poor survival rate were: age over 40 at the time of diagnosis, a presentation with abdominal symptoms, a palpable mass, a solid large tumor, bilateral tumors, extraovarian spread, and numerous mitotic figures in the tumor. It is suggested that all granulosa cell tumors should be considered as malignant and that the factors pointing to a poor prognosis are those indicating that a particular tumor has been diagnosed at a late stage in its natural history, either because it has been present for a long time or because it is highly malignant. There are no definite criteria for defining the prognosis in a case in which the tumor has been removed at any early stage in its natural life history.

Lead in urban street dust

Abstract: LEAD pollution and its effects on health are matters of general concern1,2. The potential danger to children is now receiving particular attention. Lead in various inorganic forms may be inhaled or ingested, and various sources of ingested lead (for example food, tapwater, paint) are recognised, and tolerable limits have been established. Recently, it was claimed2 that for children in urban surroundings the dust of streets and playgrounds is a potentially significant source of lead, and that the lead in such dust can be over 1,000 p.p.m. (0.1%). This is a source of lead which is not immediately controllable, but we consider that its importance as a component of the lead intake of urban children has not been sufficiently assessed.

Hegemony and consciousness in the thought of antonio gramsci

Abstract: THOUGH little known in the English-speaking world, Antonio Gramsci was perhaps the most interesting and suggestive Marxist thinker since Marx. To assess his contribution, it is important to understand the condition of Marxism in the early part of this century. The doctrine, as set forth by the theorists of the Second International, had lasped into a mechanical materialism; it had come to accept a paralysing and debilitating optimism, which led socialists to slight the consequences of either action or inaction. Capitalism, it was believed, would inevitably succumb to its internal contradictions. Accordingly, the mainstream of Marxist analysis tended to focus solely on the structural conditions of revolutionary situations. Both ‘false’ consciousness and ‘true’ consciousness were treated as necessary outcomes of certain objective circumstances ; the subjective components of social stability and revolution received scant attention. Like Lenin and Lukrics, Gramsci reacted strongly against this scientific ossification and its attendant political passivity. Essentially, he was concerned to reformulate and re-examine one of the central ambiguities of Marxist theorythe relationship between base and superstructure. His originality stemmed from his expansive vision of the role of consciousness within the framework of historical materialism. For Gramsci, ideas had consequences which could not be dismissed or reduced to a more ‘real’ world of social and economic phenomena. Herein lies the fundamental assumption behind his elusive and remarkably underanalysed concept of hegemony (egemonia), the unifying idea of his mature writings. Gramsci’s rather disjointed exposition of the concept raises a host of difficult and controversial issues, which I shall attempt to deal with in this paper. First, there is the problem of determining the precise nature of a hegemony. Roughly, the term refers to a situation wherein a social group or class is ideologically dominant. But what exactly does this mean? Then there is the question of how a hegemony arises. To answer this, we shall have to explore Gramsci’s ideas on the nature of historical materialism, the historic role of the intellectuals, and the functions of the revolutionary party-ideas the interpretation of which has given rise to acrimonious debate in Italian academic and political circles. In the final part of my discussion, I shall relate the concept of hegemony to a contemporary controversy in sociology: that between the school of thought which holds a consensual model of industrial society (i.e,, consensus theory) and the school which focuses on conflict and value differentiation (i.e., conflict, or coercion, theory). It will be my argument here that Gramsci’s thoughts on hegemony and

Crystal deformation in aromatic polyesters

Abstract: A study has been carried out of the changes in the x-ray diffraction patterns which occur when oriented fibers or tapes of poly(trimethylene terephthalate) (3GT) and poly-(tetramethylene terephthalate) (4GT) are subjected to mechanical tensile stress. Although the polymers show very different behavior in detail, in both cases comparatively large reversible lattice strains are observed (∼ several %). The diffraction pattern of 3GT changes monotonically with increasing macroscopic strain, suggesting that the lattice responds immediately to the applied stress, and deforms as though it were a coiled spring. In 4GT, on the other hand, there is no detectable change in the x-ray diffraction pattern at low macroscopic strains, i.e., low values of the applied stress. At higher stresses, changes in the pattern occur which suggest a definite change in the crystal structure. Finally at the highest values of applied stress, the lattice deformations cease to increase. A preliminary discussion is presented of the relationship of these x-ray diffraction results to the mechanical stress–strain behavior.

The properties of rubber in pure homogeneous strain

Abstract: Measurements are reported on the relationship between the principal stresses t1 and t2 and the corresponding extension ratios lambda 1 and lambda 2 in the general biaxial strain of a rubber sheet. The resulting data are shown to be consistent with the Valanis-Landel hypothesis, according to which the strain energy W is a separable function w( lambda ) of the principal extension ratios. The formulation of the series for lambda (dw/d lambda ) in terms of strain invariants I1 and I2 enables delta W/ delta I1 and delta W/ delta I2 to be accurately calculated for any values of I1 and I2. It is concluded that both delta W/ delta I1 and delta W/ delta I2 are functions of both I1 and I2. The results confirm the conclusions of earlier workers that the empirical Mooney constants derived from uniaxial extension or compression bear no direct relation to the values of delta W/ delta I1 and delta W/ delta I2.

An investigation of the centres of pressure under the foot while walking.

Abstract: The forces under the foot while walking have been measured using a high sensitivity force-plate of the strip-suspended type combined with simultaneous filming of the sole of the foot. The recording of data and the calculation and plotting of results were much simplified by computer aid. Normal and abnormal feet, both barefoot and shod, were investigated in sixteen subjects. It was found that in normal barefoot walking the forefoot carried a total load of the order of three times that of the heel. When footwear was worn the function of the forefoot was progressively reduced as the rigidity of the sole of the shoe increased. Painful conditions of the forefoot also produced a large reduction in the proportion of the total load transferred.

The structure and innervation of smooth muscle in the wall of the bladder neck and proximal urethra.

Abstract: Neurohistochemical and electron microscopic techniques have been employed to compare the structure and autonomic innervation of the bladder detrusor with that of the bladder neck and urethra in male and female cats, rats and guinea-pigs. In all specimens the structure and arrangement of smooth muscle in the detrusor was different from that in the bladder neck and proximal urethra. In male specimens this circular smooth muscle extended into the proximal urethra as far as the entrance of the ejaculatory ducts. A similar muscle coat was less well developed in the female but could be identified along the length of the urethra. Differences in the distribution of autonomic nerves have also been demonstrated. Presumptive cholinergic nerves were frequently encountered amongst the smooth muscle cells of the detrusor whilst noradrenergic nerves were relatively sparse. In contrast, muscle in the bladder neck and urethra was richly innervated by both types of autonomic nerve. In the male these findings are considered to provide support for the concept of a sphincteric mechanism which prevents retrograde ejaculation. In both sexes the possible functional role of the autonomic innervation of the bladder neck and proximal urethra during micturition has also been discussed.

Melting behaviour of low molecular weight poly (ethylene-oxide) fractions

Abstract: Two available theories of melting in extended chain polymer crystals are critically examined and compared with calorimetric data. Melting points, T m , and enthalpy of fusion, ΔH, have been measured for extended-chain crystals of poly(ethylene-oxide) fractions, covering a wide range of molecular weights. It appears that the theory of Flory and Vrij is the most appropriate to describe the present results and literature data. Application of this theory to experiments yields T m (∞) = (68.9 ± 0.4) °C and suggests that the value of the surface free energy, σ e , lies within 0.34 and 0.81 Kcal/mole, its enthalpic part (ΔH e /2) being (4.18 ± 0.22) Kcal/mole. Such a low value of σ e may be attributed to hydrogen bonding of OH end-groups located in the disordered surface layer of closely stacked crystalline lamellae.

The sine-Gordon equation as a model classical field theory

Abstract: The sine-Gordon equation ϕxx−ϕxx=m2 sinϕ is considered as a model one-dimensional classical field theory with particlelike solutions The model has applications in many branches of physics and gives an exact description of the interaction of an arbitrary number of elementary particles and bound-state composite particles

The stoicheiometry of the absorption of protons with phosphate and L-glutamate by yeasts of the genus Saccharomyces.

Abstract: 1. A study was made of the pH changes occurring when 0.1-4 mumol of glutamate, phosphate and certain phosphate esters was added at about pH 4.8 to washed cell preparations (50 mg dry wt.) of strains of Saccharomyces. The system also contained deoxyglucose and antimycin to inhibit energy metabolism and so prevent proton ejection from the yeast. 2. A strain of Sacc. carlsbergensis was grown in a chemostat with a limiting supply of phosphate in order to enhance the subsequent rate of phosphate transfer into the yeast. These preparations absorbed 0.2 mumol of phosphate with about 3 equiv. of protons/mol of phosphate. The charge balance was maintained by the efflux of 2 equiv. of K-+ from the yeast. 3. Larger amounts of phosphate were absorbed with fewer proton equivalents. 4. Arsenate and phosphate caused similar pH changes. 5. Glucose 6-phosphate, ATP and certain order phosphate esters each initiated a rise in pH, possibly because hydrolytic extracellular enzymes released phosphate that was subsequently absorbed. 6. Four strains of yeast were grown with glutamate as principal source of nitrogen. Each absorbed extra protons in the presence of L-glutamate. 7. One of them, a strain of Sacc. cerevisiae, absorbed 0.2 mumol of glutamate with 3equiv. of protons/mol of glutamate, and in these circumstances 1-2 equiv. of K-+ left the yeast cells. 8. The role of ionic gradients in the transport of these anions is discussed.

The effect of excluded volume on polymer dispersant action

Abstract: Polymer-stabilized colloid particles are modelled theoretically by plane surfaces on to which polymer chains are adsorbed by one end only. Interactions between segments of the polymer are treated as an excluded volume effect. It is shown that for high surface densities the polymer distribution function exactly satisfies a one dimensional equation which is solved numerically for two values of excluded volume to give the polymer segment density distributions and the free energy of interaction for various separations of the plane surfaces. It is found that a positive value of excluded volume greatly increases the repulsive free energy compared with that for chains with zero excluded volume, particularly at large separation distances of the surfaces. Excluded volume effects must therefore play an important part in the stabilization of colloids by adsorbed polymer.

Sigmoid curves, non-linear double-reciprocal plots and allosterism.

Abstract: 1. The theory of plane curves was applied to the graphical methods used in enzyme kinetics and a mathematical analysis of the possible graph shapes is given. 2. The belief that allosterism can be inferred from steady-state data alone is subjected to criticism and the mathematical significance of sigmoid curves and non-linear double-reciprocal plots is explored. 3. It is suggested that the usual methods of interpreting steady-state kinetic data are often based on over-restrictive assumptions which prevent maximum utilization of the available data. 4. Methods for obtaining the degree of the rate equation from graph shapes obtained directly from initial-rate measurements and from replots of asymptotic behaviour as chi approach the level 0 and chi approach the level infinity are discussed. 5. Detailed proofs of the theorems given in the text have been deposited as Supplementary Publication SUP 50049 (10 pages) at the British Library (Lending Division), Boston Spa, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1975), 145, 5.

The Organisation of Chalcid-Dominated Parasitoid Communities Centred upon Endophytic Hosts

Abstract: The phytophagous larvae of many small endopterygote insect species complete their development inside plant tissue. Some inhabit stems or floral parts, others mine leaves and the most specialised induce hypertrophy of plant tissue to produce galls. Such endophytic species enjoy an environment largely protected from climatic extremes and one that is seldom breached by predators. Endophytes, however, are usually very vulnerable to the attack of parasitoids and they can support extremely complex parasitoid communities. These communities are self-contained in the sense that scarcely any parasitoids (or parasites as they will henceforth be termed) attack more than one group of endophytic hosts. The oak gall community is qualitatively almost totally different from the deciduous tree leaf-miner community, although both communities are part of the woodland ecosystem.

Synergism between ultrasonic waves and hydrogen peroxide in the killing of micro-organisms.

Abstract: The lethal effect on different micro-organisms of ultrasonic waves and hydrogen peroxide separately and in combination was examined. Ultrasonic waves were able to disintegrate Fusobacterium nucleatum within 3 min and to kill Veillonella parvula after 15 min and Streptoccus sanguis after 20 min; 20 vols H2O2 (6% w/v) killed V. parvula, Strep. sanguis and Staphylococcus aureus after 5 min treatment, and Clostridium sporogenes spores after 25 min. Sonication of Cl. sporogenes spores, Bacillus cereus spores and Candida albicans in 20 vols H2O2, using an ultrasonic probe, was lethal to the organisms after 15, 10 and 10 min, respectively. The latter 2 organisms were not killed by 30 min exposure to either agent separately. Similar results were obtained when an ultrasonic tank was used for sonication.

More on autoregressive model fitting with noisy data by Akaike's information criterion (Corresp.)

Abstract: Davisson [131, [141 has considered the problem of determining the "order" of the signal from noisy data. Although interesting theoretically, his result is difficult to use in practice. In this correspondence, we exploit one well-known fact concerning autoregressive (AR) signals plus white noise, and using Akaike's information criterion [15], [17], we have developed one efficient procedure for determining the order of the AR signal from noisy data. The procedure is illustrated numerically using both artificially generated and real data. The connection between the preceding problem and the classical statistical problem of factor analysis is discussed.

Theory of the resistivity and Hall effect in alloys during Guinier-Preston zone formation

Abstract: The theory of the resistivity maximum, based on Bragg scattering of electrons from Guinier-Preston zones, is described and is used to construct semi-phenomenological formulae for the resistivity appropriate to various types of alloy configuration. When the parameters are determined from transport calculations the formulae will be useful in analysing the state of an alloy during ageing. It is shown, for example, that the size of cluster associated with peak resistivity varies with solute concentration and ageing temperature, but this is much less so for spherical zones than for flat zones. The theory is also able to reproduce the behaviour of the Hall coefficient in Al-Zn, which also peaks during ageing. It is argued that other zone-forming alloys may exhibit a maximum, a minimum or neither.

Exact quantum transition probabilities by the state path sum method: Collinear F + H2 reaction

Abstract: Exact quantum mechanical transition probabilities have been calculated for the collinear F + H2 →H + HF reaction by the State Path Sum method. The potential energy surface used is based on the ab initio SCF CI surface of Bender et al. For the energy range considered, four product channels are open. Pronounced level inversion is found. The dominant transition is the 3 ←0 one. It has a resonance-like energy dependence which is similar to that for the 2 ←0 transition. The 1 ←0 and 0 ←0 transition probabilities are negligible. These results are compared with those of Wu et al. and Schatz et al. who use semi-empirical LEPS surfaces.

Collagen Biosynthesis in Normal Human Skin, Normal and Hypertrophic Scar and Keloid

Abstract: A comparison of the rates of synthesis of collagen in normal skin, normal and hypertrophic scars, and keloids has been made by measuring the rate of incorporation of [14-C]-proline into peptide-bound [14-C]-hydroxyproline by tissue minces in vitro. The rate of synthesis of collagen, as measured by this technique, was significantly higher in skin than in normal scars whether the incorporation of radioactivity into hydroxyproline were expressed in terms of wet weight of tissue, weight of tissue DNA or weight of tissue hydroxyproline. The abnormal scar types exhibited similar rates of collagen synthesis, which were significantly higher than the rate in normal scars. Although the rates in both abnormal scar types appeared to be similar to that in normal skin when expressed in terms of wet weight of tissue, and weight of tissue hydroxyproline, they were seen to be lower than in skin in terms of weight of tissue DNA. The rate of synthesis of proteins generally, as measured by total radioactivity in non-diffusible peptides, was highest in normal skin and hypertrophic scar and lowest in keloid. The ratio of radioactivity in non-diffusible hydroxyproline to total non-diffusible radioactivity was almost twice as high in keloid as in normal scar, with intermediate values being observed in hypertrophic scar and normal skin. This indicated that collagen accounted for a higher proportion of the proteins being synthesised in keloid than in normal scar. The results confirm previous conclusions, from determination of the activity of the enzyme collagen proline hydroxylase, that the excessive accumulation of collagen in hypertrophic scars and keloids may, at least in part, be due to abnormally high rates of collagen synthesis in comparison to normal scars.