Showing papers by "University of London published in 1977"

The ‘universal’ dielectric response

Abstract: A review of dielectric data for a wide range of solids proves the existence of a remarkable ‘universality’ of frequency and time responses which is essentially incompatible with the multiplicity of currently accepted detailed interpretations. Certain unique features of the universal behaviour strongly suggest the dominant role of many-body interactions.

Trace Anomalies and the Hawking Effect

Abstract: The general spherically symmetric, static solution of ${\ensuremath{ abla}}_{\ensuremath{ u}}{T}_{\ensuremath{\mu}}^{\ensuremath{ u}} = 0$ in the exterior Schwarzschild metric is expressed in terms of two integration constants and two arbitrary functions, one of which is the trace of ${T}_{\ensuremath{\mu}\ensuremath{ u}}$. One constant is the magnitude of ${T}_{\mathrm{tr}}$ at infinity, and the other is determined if the physically normalized components of ${T}_{\ensuremath{\mu}\ensuremath{ u}}$ are finite on the future horizon. The trace of the stress tensor of a conformally invariant quantum field theory may be nonzero (anomalous), but must be proportional (here) to the Weyl scalar, $48{M}^{2}{r}^{\ensuremath{-}6}$; we fix the coefficient for the scalar field by indirect arguments to be ${(2880{\ensuremath{\pi}}^{2})}^{\ensuremath{-}1}$. In the two-dimensional analog, the magnitude of the Hawking blackbody effect at infinity is directly proportional to the magnitude of the anomalous trace (a multiple of the curvature scalar); a knowledge of either number completely determines the stress tensor outside a body in the final state of collapse. In four dimensions, one obtains instead a relation constraining the remaining undetermined function, which we choose as ${T}_{\ensuremath{\theta}}^{\ensuremath{\theta}}\ensuremath{-}\frac{{T}_{\ensuremath{\alpha}}^{\ensuremath{\alpha}}}{4}$. This, plus additional physical and mathematical considerations, leads us to a fairly definite, physically convincing qualitative picture of $〈{T}_{\ensuremath{\mu}\ensuremath{ u}}〉$. Groundwork is laid for explicit calculations of $〈{T}_{\ensuremath{\mu}\ensuremath{ u}}〉$.

Genetic influences and infantile autism

Abstract: IN his original description of infantile autism, Kanner suggested an “inborn defect”, because symptoms were often present from early infancy. Despite the rarity of a family history of autism and lack of a known increase in parental consanguinity, there are two reasons for suspecting hereditary influences: the 2% rate of autism in siblings is 50 times that of the general population1, and a family history of speech delay is found in about a quarter of families2. Reports of single pairs of twins with autism have not added much to our knowledge of genetic effects because of a bias toward reporting monozygotic (MZ) concordant pairs and because few reports contain both adequate clinical descriptions and evidence of zygosity1. We therefore undertook a study of a systematically collected sample of 21 pairs of same-sexed twins, one or both of whom had autism as diagnosed by the criteria of Kanner3 and Rutter4. The results reported here indicate the importance of hereditary influences in the aetiology of autism.

Analysis of Generation and Detection of Surface and Bulk Acoustic Waves by Interdigital Transducers

Abstract: Ahrroct-A method of analysis which uses a combination of analytical and numerical techniques has been developed to obtain an accurate solution to the coupled electromagnetic and acoustic fields set up by an interdigital transducer on the surface of a piezoelectric substrate. Full account is taken of the coupling to bulk modes as well as surface modes, and the solution for the charge on the electrodes includes both electrostatic charge and piezoelectrically regenerated charge. Programs have been written for interdigital arrays with uniform aperture but varying electrode width and pitch and arbitrary electrical connections. The theory is also valid for arbitrary crystal orientations. Generation and detection may be analyzed separately with information being provided on the partition of power into the various acoustic modes and the external load impedance, and the bulk wave radiation patterns are also computed. The program may also be used to find the insertion loss of a pair of transducers. Results are presented for the BleusteinGulyaev orientation of PZT-4 ceramic and the YZ and 41” rotated YX orientations of lithium niobate.

The identification by isoenzyme patterns of two distinct strain-groups of Trypanosoma cruzi, circulating independently in a rural area of Brazil

Abstract: Culture forms of 17 Trypanosoma cruzi stocks, primarily isolated from a rural area of endemic Chagas disease at Sao Felipe, Bahia, Brazil, were compared by the electrophoretic patterns of six enzymes: aspartate aminotransferase, alanine aminotransferase, glucose-6-phosphate dehydrogenase, malate dehydrogenase (decarb-oxylating) (NADP+), glucosephosphate isomerase and phosphoglucomutase. Two markedly distinct combinations of isoenzyme patterns were seen, justifying the arrangement of the 17 stocks into two strain-groups, each of which was enzymically homogeneous. One combination was characteristic of the 11 domestic stocks of T. cruzi derived from both human infections and domiciliated animals; the second was characteristic of the six sylvatic stocks derived from opossums and a sylvatic triatomine species. The enzyme patterns were independent of the original host and the type of culture medium used. Distinction of the two strain-groups accords with epidemiological evidence that the domestic and sylvatic transmission cycles in Sao Felipe do not overlap. It is suggested that the diverse enzyme characters of the two strain-groups circulating in Sao Felipe reflect diverse origins; the domestic form of T. cruzi probably invaded the area from the south of Brazil with the domestic triatomine vector, Panstrongylus megistus.

Pharmacokinetics and concentration‐effect relationships of intravenous and oral clonidine

Abstract: The kinetics of the disposition of intravenous and oral clonidine in five normotensive subjects have been determined. It is proposed that a two-compartment model adequately describes the disposition of the drug. The drug is rapidly distributed (t1/2alpha = 10.8 +/- 4.7 min) but slowly elimainated (t1/2beta = 8.5 +/- 0.9 hr). The bioavailability of oral clonidine in the tablets tested averaged 75.2% and 40 to 50% of the bioavailable dose is excreted unchanged in urine. Renal clearance of the drug showed considerable intersubject variation (1.82 +/- 0.34 ml/min/kg) and exceed the calculated glomerular filtration rate in some subjects. Oral and intravenous clonidine induced significant falls in blood pressure (greater than 20/15 mm Hg) in our normotensive subjects and consistently caused marked sedation and dryness of the mouth. Sedation and salivary flow correlated with plasma clonidine concentration over the range 0 to 4 ng/ml. Falls in blood pressure were related to plasma concentration to 1.5 to 2 ng/ml but at higher concentrations the hypotensive effect was attenuated.

An index of rurality for England and Wales

Abstract: Cloke P. J. (1977) An index of rurality for England and Wales, Reg. Studies 11, 41–46. Rurality is defined in terms of selected discriminating variables, from which an index of rurality is formulated using principal components analysis. Distributions of four classifications of rurality are presented and both problematical remote rural areas and those suffering extreme urban pressure are identified. Data generated by the index formulation is found to be both a useful tool for studies involving comparison or contrast between rural areas, and an aid to the possible standardisation of planning solutions in areas with similar problems. An insight is also offered into patterns of rural change and the changing nature of rurality itself.

Analysis of autoxidized fats by gas chromatography-mass spectrometry: I. Methyl oleate.

Abstract: A structural investigation of autoxidation products of methyl oleate was carried out by gas chromatography-mass spectrometry (GC-MS) of trimethylsilyl (TMS) ether derivatives. GC-MS using computer plots of selected masses afforded structural assignments of GC peaks due to incompletely resolved mixtures. This method provided evidence of epoxy and keto esters which are not completely separated from the main components consisting of the TMS derivatives of the allylic hydroxy esters. Use of an MS-computer system also showed that the hydroxyoctadecanoate TMS ethers were partially separated by GC. The use of synthetic hydroxyoctadecanoates for the first time enabled us to demonstrate the quantitative reliability of a GC-MS computer summation approach to analyze the isomeric composition of oleate hydroperoxides (as the saturated TMS ether derivatives). Consistently higher concentrations were found of the 8- and 11-hydroperoxides than of the 9- and 10-hydroperoxides. Minor products of autoxidation identified by GC-MS include allylic enones, isomeric epoxyoctadecanoates, dihydroxyctadecenoates, and dihydroxyoctadecanoates.

Measurement of heart-rate variability: Part 1-Comparative study of heart-rate variability analysis methods.

Abstract: A definition of heart-rate variability (h.r.v.) is given. The use of h.r.v. measurement in both clinical applications and the neural cardiovascular research is discussed. For the latter applications, four different signals describing h.r.v. are reviewed. It is shown that these signals are based on modifications of one model, namely the integral pulse frequency modulator. In Part 2, a hardware device for measuring h.r.v. based on one of these modifications is described.

Total protein synthesis in elderly people: a comparison of results with [15N]glycine and [14C]leucine.

Abstract: 1. Total body protein turnover was studied in six elderly patients. 2. During the study they were fed by continuous infusion of a liquid formula through a nasogastric tube. l-[1- 14 C]Leucine and [ 15 N]glycine were infused at a constant rate for 30 h. The labelled glycine was infused into the intragastric line; the labelled leucine was given either by this route or intravenously. 3. The specific radioactivity of free leucine in plasma and the rate of output of 14 CO 2 in expired air both reached a plateau at 10 h, and remained constant until the end of the infusion at 30 h. 4. The 15 N abundance in urinary urea and total N was very similar. In neither was a plateau reached by 30 h but in four out of the six patients the abundance in urinary NH 4 + had attained a plateau by the end of the infusion. 5. Flux rates and rates of protein synthesis were calculated in four ways: (A) from the specific radioactivity of plasma leucine at plateau; (B) from the proportion of dose excreted as 14 CO 2 at plateau; (C) from the final rates of 15 N excretion in urea or total urinary N; (D) from the final or plateau rates of 15 N excretion in urinary NH 4 + . 6. On average, the estimates of synthesis rate obtained by methods B and C agreed closely; those given by methods A and D were lower. Methods A, B and D ranked the individual patients in almost identical order. 7. The comparison of methods makes it possible to examine the validity of the assumptions on which the different methods depend. Method B is probably theoretically the most satisfactory and, of the methods used in this work, probably gives the best estimate of the absolute turnover rate. The other methods can be used for comparative purposes. 8. The results suggest that the rate of protein turnover is reduced in the elderly, compared with younger subjects.

Functional and structural changes after disuse of human muscle.

Abstract: 1. Seven patients who had suffered unilateral leg fracture were studied after removal of immobilizing plaster casts. 2. Leg volume measured anthropometrically was reduced by 12% in the injured leg (5-68 +/- 1-05 litres) compared with the uninjured (6-43 +/- 0-87 litres). Associated with this loss was a similar reduction in the net maximum oxygen uptake achieved in one-leg cycling, from 1-89 +/- 0-21 1/min in the uninjured leg to 1-57 +/- 0-18 1/min in the injured. 3. Measured by a percutaneous needle biopsy technique, a reduction of 42% was found in the cross-sectional area of the muscle fibres sampled from the vastus lateralis of the injured compared with the uninjured leg. 4. Staining for myosin adenosine triphosphatase activity showed that both type I and II fibres were affected, being reduced respectively from 3410 to 1840 micronm2 and from 3810 to 2390 micronm2 cross-sectional area. 5. Possible reasons and implications are discussed for the discrepancy between the magnitude of the difference observed in the gross measurement of leg function (maximum oxygen uptake) and structure (leg volume) as compared with the cellular level (cross-sectional fibre area).

Protection of mice against Babesia spp. and Plasmodium spp. with killed Corynebacterium parvum.

Abstract: Mice which had been pre-treated with killed Corynebacterium parvum given intravenously or intraperitoneally, but not subcutaneously, were completely resistant ot infection withBabesia microti or B. rodhaini, and protected from death caused by Plasmodium vinckeior P. chabaudiinfection. There is evidence that the parasites died within circulating erythrocytes. This occurred much too soon for a specific antibody response to be evoked, and no antibody could be detected by the indirect fluorescent-anitbody technique. Thus it is suggested that a non-secific soluble mediator may play an important role in the protection observed.

Proposals for a stable classification of the Phlebotomine sandflies (Diptera: Psychodidae)

Abstract: . A practical system of classification and nomenclature for the Phlebotomine sandflies of the world is suggested, in the light of a re-examination of the early taxonomic literature and a critical appraisal of recent studies. A stable and simple classification of the sandflies as the subfamily Phlebotominae, family Psychodidae, is given, in which are recognized only five genera but a larger number of subgenera, species groups and lesser, informal, categories. The various groupings, many of which are discussed, are considered to form a stable general framework with flexible subdivisions into which recent and future ideas may be assimilated. The system should cause minimum confusion and give maximum ease of data-retrieval to taxonomists and other scientists concerned with the classification of sandflies for pure or applied purposes.

Domestic labour and capital

Abstract: The direct products of domestic labour are not commodities; such products as clean clothes and cooked meals are not produced for the market by domestic labour and are not exchanged. Rather, they are produced for the direct satisfaction, without further transformation, of the needs of the producer and her family. In this sense domestic labour is private production. But it is not only distinguished by its location in non commodity production; it is also private production in another sense. No division of labour exists within its realm. All housewives perform very similar tasks, and they perform them in isolation, unless aided by other members of their families. Neither of the types of division of labour that Marx described as operating within commodity production—the a priori division of labour between workers employed by an individual capital through the organising control and authority of the capitalist, and the a posteriori social division of labour between workers employed by different capitals which, through the market, operates via the coercive force of competition—neither of these divisions of labour touches domestic labour. The only division of labour to which domestic labour is subject is that it is divided from commodity production. Indeed, this division comprises the specific form that the sexual division of labour, in its broadest sense, takes in capitalist society.

An evaluation of an interview assessment of marriage.

Abstract: An interview assessment of marriage relationships is described. It is shown to have good inter-rater reliability, high consistency across the accounts of both marriage partners and to be resistant to methodologic bias. A four-year follow-up study demonstrated high predictive validity to later marriage breakdown. The marriage measure also showed a strong association with behavioural deviance in the children. The intercorrelations between individual measures of various aspects of the marriage and the summary are given. A shortened version of the interview is described and preliminary findings are given on its validity.

D-α-Aminoadipate as a selective antagonist of amino acid-induced and synaptic excitation of mammalian spinal neurones

Abstract: D-α-Aminoadipate as a selective antagonist of amino acid-induced and synaptic excitation of mammalian spinal neurones