Showing papers by "University of Cambridge published in 1996"
TL;DR: This biennial Review summarizes much of particle physics, using data from previous editions.
12,798 citations
TL;DR: Three experimental techniques based on automatic swept-frequency network and impedance analysers were used to measure the dielectric properties of tissue in the frequency range 10 Hz to 20 GHz, demonstrating that good agreement was achieved between measurements using the three pieces of equipment.
Abstract: Three experimental techniques based on automatic swept-frequency network and impedance analysers were used to measure the dielectric properties of tissue in the frequency range 10 Hz to 20 GHz. The technique used in conjunction with the impedance analyser is described. Results are given for a number of human and animal tissues, at body temperature, across the frequency range, demonstrating that good agreement was achieved between measurements using the three pieces of equipment. Moreover, the measured values fall well within the body of corresponding literature data.
3,996 citations
TL;DR: A parametric model was developed to enable the prediction of dielectric data that are in line with those contained in the vast body of literature on the subject.
Abstract: A parametric model was developed to describe the variation of dielectric properties of tissues as a function of frequency. The experimental spectrum from 10 Hz to 100 GHz was modelled with four dispersion regions. The development of the model was based on recently acquired data, complemented by data surveyed from the literature. The purpose is to enable the prediction of dielectric data that are in line with those contained in the vast body of literature on the subject. The analysis was carried out on a Microsoft Excel spreadsheet. Parameters are given for 17 tissue types.
3,985 citations
TL;DR: In this paper, the authors present a unified approach to impulse response analysis which can be used for both linear and nonlinear multivariate models and demonstrate the use of these measures for a nonlinear bivariate model of US output and the unemployment rate.
3,821 citations
TL;DR: The authors report the empirical performance of Gallager's low density parity check codes on Gaussian channels, showing that performance substantially better than that of standard convolutional and concatenated codes can be achieved.
Abstract: The authors report the empirical performance of Gallager's low density parity check codes on Gaussian channels. They show that performance substantially better than that of standard convolutional and concatenated codes can be achieved; indeed the performance is almost as close to the Shannon limit as that of turbo codes.
3,032 citations
TL;DR: The dielectric properties of tissues have been extracted from the literature of the past five decades and presented in a graphical format to assess the current state of knowledge, expose the gaps there are and provide a basis for the evaluation and analysis of corresponding data from an on-going measurement programme.
Abstract: The dielectric properties of tissues have been extracted from the literature of the past five decades and presented in a graphical format. The purpose is to assess the current state of knowledge, expose the gaps there are and provide a basis for the evaluation and analysis of corresponding data from an on-going measurement programme.
2,932 citations
TL;DR: It is concluded that in patients with angiographically proven symptomatic coronary atherosclerosis, alpha-tocopherol treatment substantially reduces the rate of non-fatal MI, with beneficial effects apparent after 1 year of treatment.
2,032 citations
TL;DR: Innate immunity has been considered only to provide rapid, incomplete antimicrobial host defense until the slower, more definitive acquired immune response develops but may have an additional role in determining which antigens the acquired immune system responds to and the nature of that response.
Abstract: Innate immunity has been considered only to provide rapid, incomplete antimicrobial host defense until the slower, more definitive acquired immune response develops. However, innate immunity may have an additional role in determining which antigens the acquired immune system responds to and the nature of that response. Knowledge of the molecules and pathways involved may create new therapeutic options for infectious and autoimmune diseases.
1,812 citations
TL;DR: Whole-genome scanning by spectral karyotyping allowed instantaneous visualization of defined emission spectra for each human chromosome after fluorescence in situ hybridization, and all human chromosomes were simultaneously identified.
Abstract: The simultaneous and unequivocal discernment of all human chromosomes in different colors would be of significant clinical and biologic importance. Whole-genome scanning by spectral karyotyping allowed instantaneous visualization of defined emission spectra for each human chromosome after fluorescence in situ hybridization. By means of computer separation (classification) of spectra, spectrally overlapping chromosome-specific DNA probes could be resolved, and all human chromosomes were simultaneously identified.
1,806 citations
TL;DR: It is shown that CBP has intrinsic HAT activity, and Targeting CBP-associated H AT activity to specific promoters may be a mechanism by which E1A acts as a transcriptional activator.
Abstract: The CBP protein acts as a transcriptional adaptor for many different transcription factors by directly contacting DNA-bound activators. One mechanism by which CBP is thought to stimulate transcription is by recruiting the histone acetyltransferase (HAT) P/CAF to the promoter. Here we show that CBP has intrinsic HAT activity. The HAT domain of CBP is adjacent to the binding site for the transcriptional activator E1A. Although E1A displaces P/CAF from CBP, it does not disrupt the CBP-associated HAT activity. Thus E1A carries HAT activity when complexed with CBP. Targeting CBP-associated HAT activity to specific promoters may therefore be a mechanism by which E1A acts as a transcriptional activator.
1,783 citations
TL;DR: In this article, the authors visualized the airflow around the wings of the hawkmoth Manduca sexta and a 'hovering' large mechanical model, and found an intense leading-edge vortex was found on the downstroke, of sufficient strength to explain the high-lift forces.
Abstract: INSECTS cannot fly, according to the conventional laws of aerodynamics: during flapping flight, their wings produce more lift than during steady motion at the same velocities and angles of attack1–5. Measured instantaneous lift forces also show qualitative and quantitative disagreement with the forces predicted by conventional aerodynamic theories6–9. The importance of high-life aerodynamic mechanisms is now widely recognized but, except for the specialized fling mechanism used by some insect species1,10–13, the source of extra lift remains unknown. We have now visualized the airflow around the wings of the hawkmoth Manduca sexta and a 'hovering' large mechanical model—the flapper. An intense leading-edge vortex was found on the down-stroke, of sufficient strength to explain the high-lift forces. The vortex is created by dynamic stall, and not by the rotational lift mechanisms that have been postulated for insect flight14–16. The vortex spirals out towards the wingtip with a spanwise velocity comparable to the flapping velocity. The three-dimensional flow is similar to the conical leading-edge vortex found on delta wings, with the spanwise flow stabilizing the vortex.
TL;DR: It is demonstrated that disinhibition, or a loss of inhibitory control, can be selective for particular cognitive functions and that different regions of the prefrontal cortex provide inhibitory Control in different aspects of cognitive processing.
Abstract: The prefrontal cortex is implicated in such human characteristics as volition, planning, abstract reasoning and affect. Frontal-lobe damage can cause disinhibition such that the behaviour of a subject is guided by previously acquired responses that are inappropriate to the current situation. Here we demonstrate that disinhibition, or a loss of inhibitory control, can be selective for particular cognitive functions and that different regions of the prefrontal cortex provide inhibitory control in different aspects of cognitive processing. Thus, whereas damage to the lateral prefrontal cortex (Brodmann's area 9) in monkeys causes a loss of inhibitory control in attentional selection, damage to the orbito-frontal cortex in monkeys causes a loss of inhibitory control in 'affective' processing, thereby impairing the ability to alter behaviour in response to fluctuations in the emotional significance of stimuli. These findings not only support the view that the prefrontal cortex has multiple functions, but also provide evidence for the distribution of different cognitive functions within specific regions of prefrontal cortex.
TL;DR: Depressed mothers were less sensitively attuned to their infants, and were less affirming and more negating of infant experience, and similar difficulties in maternal interactions were also evident in the context of social and personal adversity.
Abstract: The impact of maternal depression and adversity on mother-infant face-to-face interactions at 2 months, and on subsequent infant cognitive development and attachment, was examined in a low-risk sample of primiparous women and their infants. The severe disturbances in mother-infant engagement characteristic of depressed groups in disadvantaged populations were not evident in the context of postpartum mood disorder in the present study. However, compared to well women, depressed mothers were less sensitively attuned to their infants, and were less affirming and more negating of infant experience. Similar difficulties in maternal interactions were also evident in the context of social and personal adversity. Disturbances in early mother-infant interactions were found to be predictive of poorer infant cognitive outcome at 18 months. Infant attachment, by contrast, was not related to the quality of 2-month interactions, but was significantly associated with the occurrence of adversity, as well as postpartum depression.
TL;DR: The analysis of the behavioural and neural mechanisms of reinforcement and motivation has benefited from the recent application of learning theory and better anatomical knowledge of the connectivity of certain key neural structures, such as the nucleus accumbens.
TL;DR: C3d is a molecular adjuvant of innate immunity that profoundly influences an acquired immune response and is found to differentiate between harmful and innocuous antigens.
Abstract: An optimal immune response should differentiate between harmful and innocuous antigens. Primitive systems of innate immunity, such as the complement system, may play a role in this distinction. When activated, the C3 component of complement attaches to potential antigens on microorganisms. To determine whether this alters acquired immune recognition, mice were immunized with a recombinant model antigen, hen egg lysozyme (HEL), fused to murine C3d. HEL bearing two and three copies of C3d was 1000- and 10,000-fold more immunogenic, respectively, than HEL alone. Thus, C3d is a molecular adjuvant of innate immunity that profoundly influences an acquired immune response.
TL;DR: A double-blind, placebo-controlled, multicentre study to confirm that riluzole is well tolerated and lengthens survival of patients with ALS and suggests that the 100 mg dose of rILuzole has the best benefit-to-risk ratio.
TL;DR: [3H]Gabapentin is the first pharmacological agent described that interacts with an α subunit of a voltage-dependent Ca channel, and binding activity closely followed the elution of the α sub unit.
Aarhus University1, University of Southern California2, Sternberg Astronomical Institute3, Tata Institute of Fundamental Research4, Queen Mary University of London5, University of Toronto6, Los Alamos National Laboratory7, Yale University8, University of Vienna9, University of Liège10, University of Cambridge11, Saint Mary's University12, Lawrence Livermore National Laboratory13, Stanford University14, Goddard Space Flight Center15, Technische Universität München16, University of California, Los Angeles17
TL;DR: Data from the GONG project and other helioseismic experiments reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone, which is plausible that the sound-speed differences reflect weak mixing in stellar interiors.
Abstract: Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations.
18 Nov 1996
TL;DR: It is concluded that trusting tamper resistance is problematic; smartcards are broken routinely, and even a device that was described by a government signals agency as 'the most secure processor generally available' turns out to be vulnerable.
Abstract: An increasing number of systems from pay-TV to electronic purses, rely on the tamper resistance of smartcards and other security processors. We describe a number of attacks on such systems -- some old, some new and some that are simply little known outside the chip testing community. We conclude that trusting tamper resistance is problematic; smartcards are broken routinely, and even a device that was described by a government signals agency as 'the most secure processor generally available' turns out to be vulnerable. Designers of secure systems should consider the consequences with care.
TL;DR: In this paper, the authors provide an overview of ethical issues related to social research with children, focusing on how children are positioned as vulnerable, incompetent and relatively powerless in society in general, and how this conceptualisation of children needs to be taken into account in social research.
Abstract: This paper attempts to provide an overview of ethical issues related to social research with children. It sets the discussion in the context of current debates about researching children in the UK, and explores the extent to which children should be regarded as similar to, or different from, adults in social research, focusing on how children are positioned as vulnerable, incompetent and relatively powerless in society in general, and how this conceptualisation of children needs to be taken into account in social research. The paper concludes with some practical and methodological suggestions.
University of Cambridge1, Harvard University2, International Agency for Research on Cancer3, Utrecht University4, Osaka University5, University of Sydney6, Heidelberg University7, Dartmouth College8, University of Pisa9, Medical University of Vienna10, Karolinska Institutet11, University of Zurich12, McGill University13, Mayo Clinic14, Université de Montréal15, University of Hamburg16, Cancer Research UK17, Queen's University18
TL;DR: It is suggested that genotype-phenotype correlations do exist and, if made reliably absolute, could prove useful in the future in clinical management with respect to screening, surveillance, and prophylaxis, as well as provide insight into the genetic effects of particular mutations.
Abstract: Objective. —Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominant disorder. The 3 recognized subtypes include MEN 2A, characterized by medullary thyroid carcinoma (MTC), pheochromocytoma (pheo), and hyperparathyroidism (HPT); MEN 2B, by MTC, pheo, and characteristic stigmata; and familial MTC (FMTC), by the presence of MTC only. The purpose of this study was to establish the relationship between specific mutations and the presence of certain disease features in MEN 2 which could help in clinical decision making. Design. —Correlative survey study of 477 MEN 2 families. Setting. —Eighteen tertiary referral centers worldwide. Patients. —A total of 477 independent MEN 2 families. Main Outcome Measures. —Association between the position and type of germline mutation in the RET proto-oncogene and the presence or absence of MTC, pheo, HPT, and/or other features in a family. Results. —There is a statistically significant association between the presence of any mutation at a specific position (codon 634) and the presence of pheo and HPT. The presence of a specific mutation, CGC at codon 634, has yet to be associated with FMTC. Conversely, mutations at codons 768 and 804 are thus far seen only with FMTC, while codon 918 mutation is MEN 2B-specific. Rare families with both MEN 2 and Hirschsprung disease were found to have MEN 2-specific codon mutations. Patients with Hirschsprung disease presenting with such mutations should be monitored for the possible development of MEN 2 tumors. Conclusions. —This consortium analysis suggests that genotype-phenotype correlations do exist and, if made reliably absolute, could prove useful in the future in clinical management with respect to screening, surveillance, and prophylaxis, as well as provide insight into the genetic effects of particular mutations.
National Institutes of Health1, Stanford University2, Massachusetts Institute of Technology3, Wellcome Trust Sanger Institute4, University of Oxford5, Wellcome Trust6, University of Michigan7, Rockefeller University8, Laval University9, J. Craig Venter Institute10, Centre national de la recherche scientifique11, Anschutz Medical Campus12, University of Cambridge13, McGill University14
TL;DR: The gene map unifies the existing genetic and physical maps with the nucleotide and protein sequence databases in a fashion that should speed the discovery of genes underlying inherited human disease.
Abstract: The human genome is thought to harbor 50,000 to 100,000 genes, of which about half have been sampled to date in the form of expressed sequence tags. An international consortium was organized to develop and map gene-based sequence tagged site markers on a set of two radiation hybrid panels and a yeast artificial chromosome library. More than 16,000 human genes have been mapped relative to a framework map that contains about 1000 polymorphic genetic markers. The gene map unifies the existing genetic and physical maps with the nucleotide and protein sequence databases in a fashion that should speed the discovery of genes underlying inherited human disease. The integrated resource is available through a site on the World Wide Web at http://www.ncbi.nlm.nih.gov/SCIENCE96/.
TL;DR: It is shown that the techniques described in this paper may be usefully applied in the field of solid state physics.
Abstract: Ab initio plane-wave electronic structure calculations are widely used in the study of bulk materials. A technique for the projection of plane-wave states onto a localized basis set is used to calculate atomic charges and bond populations by means of Mulliken analysis. We analyze a number of simple bulk crystals and find correlations of overlap population with covalency of bonding and bond strength, and effective valence charge with ionicity of bonding. Thus, we show that the techniques described in this paper may be usefully applied in the field of solid state physics. \textcopyright{}1996 The American Physical Society.
TL;DR: The broken-stick model is described and its application demonstrated on actual data sets, using the uncertainty of the location of individual zone markers, given the errors of the original data.
Abstract: SUMMARY
Current methods for numerical zonation of biostratigraphic sequences neither assess the reliability of zones identified nor provide any means of determining the number of zones that are ‘significant’ (based on structure in the data set, rather than the stochastic element). These problems can be overcome by using the broken-stick model to assess the significance of zones against a model of random distribution of zones within a sequence. The broken-stick model is described and its application demonstrated on actual data sets. Additionally, simulation modelling is used to assess the uncertainty of the location of individual zone markers, given the errors of the original data. These widely-applicable methods make it possible to identify zones rigorously and consistently. The potential in biostratigraphy and correlation includes the recognition, correlation and subdivision of chronostratipraphic units in long Quaternary sequences.
TL;DR: It is shown that non-phosphorylated recombinant tau iso-forms with three microtubule-binding repeats form paired helical-like filaments under physiological conditions in vitro, when incubated with sulphated glycosaminoglycans such as heparin or heparan sulphate.
Abstract: The paired helical filament (PHF) is the major component of the neurofibrillary deposits that form a defining neuropathological characteristic of Alzheimer's disease. PHFs are composed of microtubule-associated protein tau, in a hyperphosphorylated state. Hyperphosphorylation of tau results in its inability to bind to microtubules and is believed to precede PHF assembly. However, it is unclear whether hyperphosphorylation of tau is either necessary or sufficient for PHF formation. Here we show that non-phosphorylated recombinant tau isoforms with three microtubule-binding repeats form paired helical-like filaments under physiological conditions in vitro, when incubated with sulphated glycosaminoglycans such as heparin or heparan sulphate. Furthermore, heparin prevents tau from binding to microtubules and promotes microtubule disassembly. Finally, we show that heparan sulphate and hyperphosphorylated tau coexist in nerve cells of the Alzheimer's disease brain at the earliest known stages of neurofibrillary pathology. These findings, with previous studies which show that heparin stimulates tau phosphorylation by a number of protein kinases, indicate that sulphated glycosaminoglycans may be a key factor in the formation of the neurofibrillary lesions of Alzheimer's disease.
TL;DR: In this article, the authors test for cointegration between total energy consumption and real income of six Asian economies: India, Pakistan, Malaysia, Singapore, Indonesia and the Philippines.
Book•
22 Apr 1996TL;DR: A new division of the life course - How Long Can Anyone Go On Living - The Age of Britain as a Country: Britain be Your Age, First Adjuration - The age of the present British population, with a glimpse into its future as mentioned in this paper.
Abstract: Preface - A New Division of the Life Course - How Long Can Anyone Go On Living - The Age of Britain as a Country: Britain be Your Age, First Adjuration - The Age of the Present British Population, with a Glimpse into its Future. Britain be Your Age, Second Adjuration - The Rectangular Survival Curve and the Secular Shift in Ageing - The Emergence of the Third Age - Hostile and Demeaning Descriptions of the Elderly - The Insufficiency of the Family Group, in the Past and in the Present - Retirement and its Social History: Kin and Collectivity in Support of the Old - The General Theory of the Third Age - The Obsolescence of the Educational System, and the University of the Third Age - The Burden of the Elderly and Paying for your own Third Age - The Responsibilities of Older British People - Bibliography - Index
TL;DR: In this paper, a variational formulation is employed to derive a micromechanics-based, explicit nonlocal constitutive equation relating the ensemble averages of stress and strain for a class of random linear elastic composite materials.
Abstract: A variational formulation is employed to derive a micromechanics-based, explicit nonlocal constitutive equation relating the ensemble averages of stress and strain for a class of random linear elastic composite materials. For two-phase composites with any isotropic and statistically uniform distribution of phases (which themselves may have arbitrary shape and anisotropy), we show that the leading-order correction to a macroscopically homogeneous constitutive equation involves a term proportional to the second gradient of the ensemble average of strain. This nonlocal constitutive equation is derived in explicit closed form for isotropic material in the one case in which there exists a well-founded physical and mathematical basis for describing the material's statistics: a matrix reinforced (or weakened) by a random dispersion of nonoverlapping identical spheres. By assessing, when the applied loading is spatially-varying, the magnitude of the nonlocal term in this constitutive equation compared to the portion of the equation that relates ensemble average stresses and strains through a constant “overall” modulus tensor, we derive quantitative estimates for the minimum representative volume element (RVE) size, defined here as that over which the usual macroscopically homogeneous “effective modulus” constitutive models for composites can be expected to apply. Remarkably, for a maximum error of 5% of the constant “overall” modulus term, we show that the minimum RVE size is at most twice the reinforcement diameter for any reinforcement concentration level, for several sets of matrix and reinforcement moduli characterizing large classes of important structural materials. Such estimates seem essential for determining the minimum structural component size that can be treated by macroscopically homogeneous composite material constitutive representations, and also for the development of a fundamentally-based macroscopic fracture mechanics theory for composites. Finally, we relate our nonlocal constitutive equation explicitly to the ensemble average strain energy, and show how it is consistent with the stationary energy principle.
TL;DR: It is shown that glial-cell-line-derived neurotrophic factor (GDNF)7, a distant member of the transforming growth factor(TGF)-β superfamily, signals through the Ret RTK, and that GDNF, in addition to its potential role in the differentiation and survival of central nervous system neurons8–12, has profound effects on kidney organogenesis and the development of the peripheral nervous system.
Abstract: MUTATIONAL analysis in humans and mice has demonstrated that Ret, the product of the c-ret proto-oncogene, a member of the receptor tyrosine kinase (RTK) superfamily1, is essential for development of the enteric nervous system and kidney2–6. Despite the established role of Ret in mammalian embryogenesis, its cognate ligand(s) is currently unknown. Here we demonstrate, by using a Xenopus embryo bioassay, that glial-cell-line-derived neurotrophic factor (GDNF)7, a distant member of the transforming growth factor(TGF)-β superfamily, signals through the Ret RTK. Furthermore, using explant cultures from wild-type and Ret-deficient mouse embryos4, we show that normal c-ret function is necessary for GDNF signalling in the peripheral nervous system. Our data strongly suggest that Ret is a functional receptor for GDNF, and that GDNF, in addition to its potential role in the differentiation and survival of central nervous system neurons8–12, has profound effects on kidney organogenesis and the development of the peripheral nervous system.