Showing papers by "University of Southampton published in 1995"

A Theory of Incentives in Procurement and Regulation.

Abstract: More then just a textbook, A Theory of Incentives in Procurement and Regulation will guide economists' research on regulation for years to come. It makes a difficult and large literature of the new regulatory economics accessible to the average graduate student, while offering insights into the theoretical ideas and stratagems not available elsewhere. Based on their pathbreaking work in the application of principal-agent theory to questions of regulation, Laffont and Tirole develop a synthetic approach, with a particular, though not exclusive, focus on the regulation of natural monopolies such as military contractors, utility companies, and transportation authorities. The book's clear and logical organization begins with an introduction that summarizes regulatory practices, recounts the history of thought that led to the emergence of the new regulatory economics, sets up the basic structure of the model, and previews the economic questions tackled in the next seventeen chapters. The structure of the model developed in the introductory chapter remains the same throughout subsequent chapters, ensuring both stability and consistency. The concluding chapter discusses important areas for future work in regulatory economics. Each chapter opens with a discussion of the economic issues, an informal description of the applicable model, and an overview of the results and intuition. It then develops the formal analysis, including sufficient explanations for those with little training in information economics or game theory. Bibliographic notes provide a historical perspective of developments in the area and a description of complementary research. Detailed proofs are given of all major conclusions, making the book valuable as a source of modern research techniques. There is a large set of review problems at the end of the book.

Fetal origins of coronary heart disease

Abstract: The fetal origins hypothesis states that fetal undernutrition in middle to late gestation, which leads to disproportionate fetal growth, programmes later coronary heart disease. Animal studies have shown that undernutrition before birth programmes persisting changes in a range of metabolic, physiological, and structural parameters. Studies in humans have shown that men and women whose birth weights were at the lower end of the normal range, who were thin or short at birth, or who were small in relation to placental size have increased rates of coronary heart disease. We are beginning to understand something of the mechanisms underlying these associations. The programming of blood pressure, insulin responses to glucose, cholesterol metabolism, blood coagulation, and hormonal settings are all areas of active research.

Liquid-crystalline phases as templates for the synthesis of mesoporous silica

Abstract: THE synthesis of inorganic mesoporous materials using ionic surfactant template molecules was first reported in 19921,2, and surfactant-mediated synthesis has since been used to form a variety of mesoporous materials3–8. Such materials could find application in catalysis, membrane and separation technology, and molecular engineering. Previous syntheses have used low surfactant concen-trations, and the templating mechanism (which is still controversial) is thought to be a cooperative process involving the interaction of inorganic ions with discrete surfactant aggregates1,2,5,9. Here we report the templating of silica mesostructures from ordered liquid-crystalline mesophases: the resulting silica phase, with pores of ∼3 nm diameter, is a cast of the organic mesophase. As the phase diagram of the surfactant/silica/water system at high surfactant concentration is similar to the (known) phase diagram of surfactant/water alone, this approach should introduce an element of predictability into the synthesis of mesoporous materials.

Political Recruitment: Gender, Race and Class in the British Parliament

Abstract: 1. Puzzles in political recruitment Part I. Who Selects and How?: 2. The structure of political recruitment 3. Conservative recruitment 4. Labour recruitment 5. Minor party recruitment Part II. Who Gets Selected and Why?: 6. Supply and demand explanations 7. Gatekeeper attitudes 8. Candidate resources 9. Candidate motivation 10. Comparative candidate recruitment Part III. Does the Social Bias Matter?: 11. The values, priorities and roles of MPs 12. The personal vote 13. Reforming recruitment.

Molecular dynamics simulation of the orthobaric densities and surface tension of water

Abstract: Molecular dynamics simulations have been performed to study the liquid–vapor equilibrium of water as a function of temperature. The orthobaric densities and the surface tension of water are reported for temperatures from 316 K until 573 K. The extended simple point charge (SPC/E) interaction potential for water molecules is used with full Ewald summation. The normal and tangential components of the pressure tensor were calculated and are presented at 328 K. The nature of the long‐range contribution to the surface tension has been studied in detail. At 328 K the calculated surface tension is 66.0±3.0 mN m−1 in comparison with the experimental value of 67 mN m−1. The simulated surface tensions between 316 K and 573 K are in good agreement with experiment. The orthobaric densities are in better agreement with experimental values than those obtained from the Gibbs ensemble calculation for the SPC model of water.

Ytterbium-doped silica fiber lasers: versatile sources for the 1-1.2 /spl mu/m region

Abstract: Ytterbium-doped silica fibers exhibit very broad absorption and emission bands, from /spl sim/800 nm to /spl sim/1064 nm for absorption and /spl sim/970 nm to /spl sim/1200 nm for emission. The simplicity of the level structure provides freedom from unwanted processes such as excited state absorption, multiphonon nonradiative decay, and concentration quenching. These fiber lasers therefore offer a very efficient and convenient means of wavelength conversion from a wide variety of pump lasers, including AlGaAs and InGaAs diodes and Nd:YAG lasers. Efficient operation with narrow linewidth at any wavelength in the emission range can be conveniently achieved using fiber gratings. A wide range of application for these sources can be anticipated. In this paper, the capabilities of this versatile source are reviewed. Analytical procedures and numerical data are presented to enable design choices to be made for the wide range of operating conditions. >

The mathematics of financial derivatives : a student introduction

Abstract: Finance is one of the fastest growing areas in the modern banking and corporate world. This, together with the sophistication of modern financial products, provides a rapidly growing impetus for new mathematical models and modern mathematical methods; the area is an expanding source for novel and relevant 'real-world' mathematics. In this book the authors describe the modelling of financial derivative products from an applied mathematician's viewpoint, from modelling through analysis to elementary computation. A unified approach to modelling derivative products as partial differential equations is presented, using numerical solutions where appropriate. Some mathematics is assumed, but clear explanations are provided for material beyond elementary calculus, probability, and algebra. Over 140 exercises are included. This volume will become the standard introduction to this exciting new field for advanced undergraduate students.

The fetal and infant origins of disease

Abstract: Recent research has shown that babies who are small at birth and during infancy will be at increased risk of developing coronary heart disease and the related disorders, stroke, diabetes and hypertension during adult life [1,2]. That a person’s destiny and lifespan may be determined before birth is well known. Genetically determined diseases such as Huntington’s chorea illustrate how a long period of normal development and adult life can be prematurely brought to an end by the action of inherited defects. We are now seeing that undernutrition in utero permanently changes the body’s structure and function in ways which ‘programme’ the appearance of disease in later life. The main focus for research into the causes of coronary heart disease is the lifestyle of adults. Inappropriate behaviours, such as cigarette smoking and becoming obese, have been shown to hasten destructive processes in the body. Differences in lifestyle, however, fail to explain much about the geography of the disease, its time trends, or why one person gets the disease and another does not. In the search for a new model for the disease an important clue, suggesting that coronary heart disease might originate in utero, came from studies of death rates among newborn babies in the early years of the century [3,4]. It was found that, across England and Wales, areas which have high death rates from coronary heart disease had high death rates among newborn babies in the early years of the century. At that time the usual cause of death among newborn babies was small size [5]. The suggestion that events in childhood influence the pathogenesis of coronary heart disease is not new [6]. A focus on intra-uterine life, however, is a new point of departure for cardiovascular research.

Variable rate QAM for mobile radio

Abstract: Quadrature amplitude modulation (QAM) schemes which vary the number of modulation levels in accordance with the mobile radio fading channel variations are investigated. Important parameters considered are the fading rate and the block size used. We describe how the adaptive QAM modems can be employed and consider their use in a DECT-like TDD packet structure. System performance in the presence of cochannel interference is also considered. Simulations show that the variable rate system has about 5 dB improvement in channel SNR over a fixed 16-level QAM system for BER's between 10/sup -2/ and 10/sup -5/ and channel SNR's between 25 and 40 dB. >

Full 2-D photonic bandgaps in silica/air structures

Abstract: Full 2-D photonic bandgaps are demonstrated for all polarisations in structures with refractive index contrast as small as that of silica and air. They occur for light propagating out of the transverse plane, with a longitudinal component of wave vector. A new type of optical fibre based on these structures is proposed.

Neuropathological Diagnostic-criteria for Creutzfeldt-jakob-disease (cjd) and Other Human Spongiform Encephalopathies (prion Diseases)

Abstract: Neuropathological diagnostic criteria for Creutzfeldt-Jakob disease (CJD) and other human transmissible spongiform encephalopathies (prion diseases) are proposed for the following disease entities: CJD - sporadic, iatrogenic (recognised risk) or familial (same disease in 1st degree relative): spongiform encephalopathy in cerebral and/or cerebellar cortex and/or subcortical grey matter; or encephalopathy with prion protein (PrP) immunoreactivity (plaque and/or diffuse synaptic and/or patchy/perivacuolar types). Gerstmann-Straussler-Scheinker disease (GSS) (in family with dominantly inherited progressive ataxia and/or dementia): encephalo(myelo)pathy with multicentric PrP plaques. Familial fatal insomnia (FFI) (in member of a family with PRNP178 mutation): thalamic degeneration, variable spongiform change in cerebrum. Kuru (in the Fore population). Without PrP data, the crucial feature is the spongiform change accompanied by neuronal loss and gliosis. This spongiform change is characterised by diffuse or focally clustered small round or oval vacuoles in the neuropil of the deep cortical layers, cerebellar cortex or subcortical grey matter, which might become confluent. Spongiform change should not be confused with non-specific spongiosis. This includes status spongiosus (''spongiform state''), comprising irregular cavities in gliotic neuropil following extensive neuronal (including also lesions of ''burnt-out'' ''spongy'' changes in brain oedema and metabolic encephalopathies, and artefacts such as superficial cortical, perineuronal, or perivascular vacuolation; focal changes indistinguishable from spongiform change may occur in some cases of Alzheimer's and diffuse Lewy body diseases. Very rare cases might not be diagnosed by these criteria. Then confirmation must be sought by additional techniques such as PrP immunoblotting, preparations for electron microscopic examination of scrapie associated fibrils (SAF), molecular biologic studies, or experimental transmission.

Low-mass white dwarfs need friends: five new double-degenerate close binary stars

Abstract: We have discovered five detached close binary stars out of seven white dwarfs chosen for their low mass (<0.45 Msun). The high success rate of our observations supports the notion that evolution within a binary star is needed to obtain white dwarfs with masses below 0.45 Msun. We have measured the orbital period and radial velocity amplitude of four of our discoveries. No late-type features are seen in any of our targets at a level which forces the mass of any main-sequence companion to be less than 0.1 Msun. This, together with our measured mass functions, implies that the companion stars are in fact white dwarfs. Our observations raise the number of detached, double-degenerate close binaries with known orbital periods from two to six. All of the orbits are circular, a consequence of past interaction. We find periods of 1.1, 3.3 and 4.8 d for 1713+332, 1241-010 and 1317+453. 2331+290 has a very short period, most likely 4h, but with the 1 cycle d-1 alias at 4.8 h also a possibility. Gravitational radiation will cause this star to merge within about 2 × 10^9 yr. Close double-degenerates go through one or more stages during which the two stars orbit inside a common envelope. The long orbital periods of 1241-010 and 1317+453 suggest that the ejection of the envelope during the common-envelope phase is very efficient. The spectrum of the companion is directly detectable in 1713+332 but in none of the other systems.

Sustained attention training for unilateral neglect: Theoretical and rehabilitation implications

Abstract: Many studies have shown a co-variation of unilateral neglect with nonlateralised attentional functions. Recently, Posner has argued that there are two separate neural systems that influence the posterior attentional system which is presumed to be impaired in unilateral neglect, namely, the posterior system itself (located partly in the inferior parietal lobules) as well as a secondary modulatory sustained attention or vigilance system. This latter system is linked to the nor-epinephrine system, which is known to be more strongly represented in the right compared to the left hemisphere of the brain. If this hypothesis is true, then unilateral neglect should be improved by increasing activation of the sustained attention system. Eight patients suffering from chronic left unilateral neglect were trained to sustain their attention by a self-alerting procedure partially derived from Meichenbaum's self-instructional methods. Using a multiple-baseline-by-function design, as well as multiple-baseline-by-subject designs, statistically significant improvements in unilateral neglect as well in sustained attention were found following onset of sustained attention training, without corresponding improvements in control measures. Theoretical implications for the attentional underpinnings of unilateral neglect are discussed, as well as the rehabilitation implications of this training procedure.

Heterogeneity of human mast cells based on cytokine content.

Abstract: Human mast cells can be divided into two distinct phenotypes based on their content of neutral serine proteases, suggesting that they serve differing biologic and pathologic roles. Recently, it has been demonstrated that human mast cells are a source of several pleiotropic cytokines including IL-4, IL-5, IL-6, IL-8, and TNF-alpha, but not all mast cells contain all of these cytokines, suggesting that there is also functional heterogeneity with respect to cytokine expression. In this study, we have examined the relationship between mast cell neutral protease expression and cytokine content using immunohistochemistry. Bronchial mucosal biopsies from five normal subjects and five patients with allergic asthma, and nasal mucosal biopsies from five normal subjects and three patients with allergic rhinitis were embedded in glycol methacrylate. Sections (2 microns) were stained for IL-4, IL-5, and IL-6, adjacent to serial sections stained for tryptase and chymase. The distribution of cytokines among the tryptase+ chymase- mast cells (MCT) and tryptase+ chymase+ mast cells (MCTC) was examined by co-localization of cytokines to MCTC or MCT in serial sections using the camera-lucida. Although IL-4 was distributed among both mast cell phenotypes, it was expressed preferentially by the MCTC subset (overall 85% MCTC:15% MCT). In contrast, IL-5 and IL-6 were restricted almost exclusively to the MCT subset. Immunostaining of isolated skin mast cells (> 99% MCTC) supported these findings, with strong immunoreactivity present for IL-4 but very little for IL-5 or IL-6. These results indicate that in addition to exhibiting heterogeneity with respect to neutral protease content of the secretory granules, human mast cells are also heterogeneous with respect to cytokine content. This suggests that the biologic functions of MCTC and MCT cells differ as a result of their capacity to generate and release different cytokine profiles.

Waveguide surface plasmon resonance sensors

Abstract: Guided-wave optical biosensors have great potential for use in the field of environmental monitoring. In particular, planar waveguide technologies offer the possibility of producing compact, monolithic, multisensor devices which may be connected to instrumentation using optical fibres, allowing remote operation. Optical evanescent field sensing techniques presently under investigation include grating couplers, waveguide interferometers and surface plasmon resonance (SPR) sensors. In the latter case, the surface plasmon is generally excited using a "bulk" optical component such as a prism, and equipment using this technique is now commercially available. One potential advantage of the SPR technique is that the metal film which supports the surface plasmon may also be used as an electrode for electrochemical control of sensing reactions. However, recent reports have indicated that the "bulk" SPR devices may not ultimately be as sensitive as fully guided-wave approaches such as the Mach-Zehnder interferometer. An alternative to the "bulk" SPR devices which has recently emerged is the use of distributed coupling between a dielectric waveguide and the surface plasmon mode in a metal-coated waveguide. This has the advantage of combining greater design flexibility and the potential for monolithic integration with the well-established technique of SPR. However, at present no adequate model for the performance of these devices exists. ...

Requirement of MAP kinase for differentiation of fibroblasts to adipocytes, for insulin activation of p90 S6 kinase and for insulin or serum stimulation of DNA synthesis.

Abstract: A phosphorothioate-oligonucleotide-based antisense strategy for depleting MAP kinase was developed. The 17mer antisense probe, EAS 1, caused a potent and concentration-dependent decrease in the steady state expression of p42 and p44 MAP kinase in 3T3 L1 fibroblasts and adipocytes with submicromolar concentrations effective. Antisense EAS 1 elicited a dose-dependent inhibition of insulin- and serum-stimulated DNA synthesis. Elimination of p42 MAP kinase by > 95% and p44 MAP kinase to levels undetected blocked the ability of serum in 3T3 L1 fibroblasts and insulin in 3T3 L1 adipocytes to stimulate DNA synthesis by 87-95%. The differentiation of 3T3 L1 fibroblasts into adipocytes was prevented by 1 microM antisense EAS 1. The corresponding sense, scrambled or sense plus antisense EAS 1 phosphorothioate oligonucleotides did not deplete the p42 or p44 MAP kinase from either cell type, did not inhibit stimulation of DNA synthesis and did not interfere with differentiation. Two kinases on different MAP kinase activation pathways were not depleted by antisense EAS 1 whereas the ability of insulin to activate p90 S6 kinase was > 90% eliminated in 3T3 L1 adipocytes by 4.5 microM antisense EAS 1. In conclusion these results show that MAP kinase is required for insulin and serum stimulation of DNA synthesis, for insulin stimulation of p90 S6 kinase activity and for differentiation of 3T3 L1 cells. Moreover, the development of the antisense probe EAS 1 against a target sequence of p42 MAP kinase that is conserved in p44 MAP kinase and across a range of species provides a molecular tool of general applicability for further dissecting the precise targets and roles of MAP kinase.

Stable single-frequency traveling-wave fiber loop laser with integral saturable-absorber-based tracking narrow-band filter

Abstract: We demonstrate stable single-frequency and polarization operation of a travelling-wave Er3+:Yb3+-doped fiber loop laser by incorporating an unpumped Er3+-doped fiber section butted against a narrowband feedback reflector. The saturable absorber acts as a narrow bandpass filter which automatically tracks the lasing wavelength, thus ensuring single-frequency operation. Output powers up to 6.2 mW at 1535 nm were obtained for launched pump powers of 175 mW at 1064 nm. At this output, the RIN was less than -112 dB/Hz at frequencies above 200 kHz and the laser linewidth less than 0.95 kHz whilst the lasing frequency was observed to drift slowly (~ 170 MHz/hr) due to environmental effects.

Resolving the constrained minimal and next-to-minimal supersymmetric standard models

Abstract: We perform a detailed analysis of the next-to-minimal supersymmetric standard model (NMSSM), imposing the constraints of two-loop gauge coupling unification, universal soft supersymmetry breaking, and the correct pattern of electroweak symmetry breaking. We compare our results with those for the minimal supersymmetric standard model (MSSM) using closely related techniques and, as far as possible, a common set of input and output variables. In general, in the constrained NMSSM, there are much stronger correlations between parameters than in the constrained MSSM, and we map out the allowed parameter space. We also give a detailed discussion of how to resolve the two models experimentally, concentrating primarily on the prospects at CERN LEP II. We find that, for a top quark mass {approx_gt}150 GeV, the constrained NMSSM is only viable in regions where its spectrum is in general very similar to that of the MSSM, although there are exceptions which we explore. For example, in some corners of parameter space the lightest {ital CP}-even Higgs boson in the constrained NMSSM may be detected at LEP II with singlet-diluted couplings which may allow it to be distinguished from that of the MSSM. However, if small universal gaugino mass {ital M}{sub 1/2} is required, thenmore » we expect a standard-model-like Higgs boson which may be detected at LEP II, together with a very characteristic Higgs boson and SUSY spectrum. We also study fine-tuning in the constrained NMSSM, which is typically a more severe constraint than in the MSSM, and give a simple analytical discussion of the potential and spectrum.« less

The Two-Stage Assembly Scheduling Problem: Complexity and Approximation

Abstract: This paper introduces a new two-stage assembly scheduling problem. There are m machines at the first stage, each of which produces a component of a job. When all m components are available, a single assembly machine at the second stage completes the job. The objective is to schedule jobs on the machines so that the makespan is minimized. We show that the search for an optimal solution may be restricted to permutation schedules. The problem is proved to be NP-hard in the strong sense even when m = 2. A schedule associated with an arbitrary permutation of jobs is shown to provide a worst-case ratio bound of two, and a heuristic with a worst-case ratio bound of 2-1/m is presented. The compact vector summation technique is applied for finding approximation solutions with worst-case absolute performance guarantees.

Moving fibre/phase mask-scanning beam technique for enhanced flexibility in producing fibre gratings with uniform phase mask

Abstract: A new and flexible technique for producing photorefractive fibre gratings with a uniform phase mask is demonstrated. By slowly moving the fibre relative to the mask as the writing beam is scanned, wavelength shifts, pure apodisation and phase-shifted gratings can be achieved.

Cigarette smoking influences cytokine production and antioxidant defences.

Abstract: 1. Smoking exerts an inflammatory stimulus on lung macrophages, and smokers generally have low intakes of antioxidant micronutrients. This study was performed to investigate the relationship between whole-blood tumour necrosis factor production, plasma interleukin-6 and acute-phase protein concentration and antioxidant vitamins in smokers and non-smokers. 2. Measurement of tumour necrosis factor was conducted in whole blood stimulated with endotoxin (lipopolysaccharide), and interleukin-6 concentrations were measured in the plasma of smokers and non-smokers. Enzyme and dietary antioxidant concentrations and acute-phase proteins were determined in the two groups. 3. Tumour necrosis factor production and plasma interleukin-6 concentrations were 38% (P = 0.01) and 16% (P = 0.07) greater, respectively, in smokers than in non-smokers. Plasma vitamin A and E concentrations were unaffected by smoking; however, a 21% lower plasma vitamin C (P = 0.04) concentration was observed in smokers, than in non-smokers despite a similar intake of this vitamin by the two groups. 4. Concentrations of the acute-phase proteins alpha 1-acid glycoprotein, caeruloplasmin and alpha 2-macroglobulin were increased in the plasma of smokers compared with non-smokers by 39%, 28% and 12% respectively (P < 0.01). Our studies indicate that smokers have a compromised antioxidant status and elevated concentrations of tumour necrosis factor and interleukin-6 as a consequence of smoking. 5. These observations may provide some insight into the biological mechanisms underlying the pathology associated with smoking.

Exploring the relationship between reflectance red edge and chlorophyll concentration in slash pine leaves.

Abstract: Chlorophyll concentration is related positively to the point of maximum slope in the reflectance spectra of leaves and this point is termed the red edge. The reflectance spectra of slash pine (Pinus elliottii Engelm.) needles were measured in the field and the chlorophyll concentrations of the same needles were measured in the laboratory. The measurement errors for red edge and chlorophyll concentration were determined to be 2.2 nm (3% of mean) and 0.35 mg g(-1) (19% of mean), respectively. The red edge-chlorophyll concentration relationship was strong (r(2) = 0.82, n = 152). A red edge-chlorophyll concentration relationship for n = 100 was used with red edge measurements to estimate chlorophyll concentration with an rms error of 0.31 mg g(-1) (17% of mean, n = 52). The entire red edge-chlorophyll concentration relationship for n = 152 was also used with red edge measurements to estimate the chlorophyll concentration of samples from an earlier experiment with an rms error of 0.47 mg g(-1) (30% of mean, n = 38). We conclude that measures of red edge can be used to estimate the chlorophyll concentration of detached needles in the field with an accuracy similar to that obtained by conventional laboratory measurements.

Marine research, resources and conservation in the Azores

Abstract: 1 A history of marine research on the Azores is outlined. Until two decades ago most oceanic and littoral marine studies had been carried out by foreign scientists. Studies by Azorean scientists started to increase in the early 1980s when the University of the Azores was created. 2 Ocean circulation in this part of the Atlantic is described as a background for biogeography and diversity. The picture emerges that Azores is a ‚meeting point’ for shallow water marine fauna and flora of different origins. 3 The species composition of one of the best studied groups of organisms, the fish, is compared between locations in the northeastern Atlantic. The work on fish is also compared with other well studied groups (algae and hydroids) to highlight the interest of the Azores as a natural biogeographical experiment. 4 Studies of marine resources began less than two decades ago. The development of demersal fisheries is described focusing on the switch from small-scale artisanal fishing to more commercial fisheries. 5 Conservation of species and legislation in force for molluscs, crustaceans, fishes, marine turtles, seabirds and marine mammals are summarized. 6 Protected marine areas already designated are defined, as well as new areas recommended. 7 The paper concludes with a discussion of current threats and future management strategies.