Showing papers by "City University London published in 2006"

Guidance on the conduct of narrative synthesis in sytematic reviews

Abstract: Titles & abstract s Titles & abstracts Include N=54 Include N=121 Include N=89 Exclude N = 0 Exclude N = 1,024 Exclude N = 21

Retinal Repair by Transplantation of Photoreceptor Precursors

Abstract: Photoreceptor loss causes irreversible blindness in many retinal diseases. Repair of such damage by cell transplantation is one of the most feasible types of central nervous system repair; photoreceptor degeneration initially leaves the inner retinal circuitry intact and new photoreceptors need only make single, short synaptic connections to contribute to the retinotopic map. So far, brain- and retina-derived stem cells transplanted into adult retina have shown little evidence of being able to integrate into the outer nuclear layer and differentiate into new photoreceptors(1-4). Furthermore, there has been no demonstration that transplanted cells form functional synaptic connections with other neurons in the recipient retina or restore visual function. This might be because the mature mammalian retina lacks the ability to accept and incorporate stem cells or to promote photoreceptor differentiation. We hypothesized that committed progenitor or precursor cells at later ontogenetic stages might have a higher probability of success upon transplantation. Here we show that donor cells can integrate into the adult or degenerating retina if they are taken from the developing retina at a time coincident with the peak of rod genesis(5). These transplanted cells integrate, differentiate into rod photoreceptors, form synaptic connections and improve visual function. Furthermore, we use genetically tagged postmitotic rod precursors expressing the transcription factor Nrl (ref. 6) ( neural retina leucine zipper) to show that successfully integrated rod photoreceptors are derived only from immature post-mitotic rod precursors and not from proliferating progenitor or stem cells. These findings define the ontogenetic stage of donor cells for successful rod photoreceptor transplantation.

A cohort-based extension to the Lee–Carter model for mortality reduction factors

Abstract: The Lee–Carter modelling framework is extended through the introduction of a wider class of generalised, parametric, non-linear models. This permits the modelling and extrapolation of age-specific cohort effects as well as the more familiar age-specific period effects. The choice of error distribution is generalised.

The Unmanageable Consumer

Abstract: The Emergence Of Contemporary Consumerism The Consumer As Chooser The Consumer As Communicator The Consumer As Explorer The Consumer As Identity-Seeker The Consumer Hedonist Or Artist? The Consumer As Victim The Consumer As Rebel The Consumer As Activist The Consumer As Citizen The Unmanageable Consumer

Corneal Thickness- and Age-Related Biomechanical Properties of the Cornea Measured with the Ocular Response Analyzer

Abstract: PURPOSE. The Ocular Response Analyzer (ORA) is a new instrument that measures the corneal biomechanical response (corneal hysteresis, CH) to rapid indentation by an air jet. CH is the difference in applanation pressures (P1, P2) between the rising and falling phases of the air jet. The investigation had two parts: a characterization study and a validation study. In the characterization study, the purposes were to investigate the intraocular pressure (IOP)– dependence of CH and to characterize the performance of the ORA. In the validation study, the purposes were to investigate the association between CH and both age and central corneal thickness (CCT) and the agreement between ORA and Goldmann applanation tonometer (GAT) IOP measurements. METHODS. For the characterization study, data were collected from 105 untreated subjects (45 ocular hypertensive patients and 60 normal subjects; mean age, 60 years, range, 26 – 82). GAT and ORA measurements were performed before and after IOP lowering of one randomly selected eye with apraclonidine drops. The change in P1 and P2 (arbitrary units) in relation to change in GAT IOP was analyzed to calibrate the instrument. The relation between P1, P2, and CCT was explored and ORA IOP was derived from the analyses. For the validation study, ORA and GAT IOP and CCT were measured in 144 eyes of 144 untreated subjects (mean age, 58 years; range, 19 – 83). The characterization calculations were applied to the dataset and values of CH and ORA IOP were calculated. The relationship between CH and both subject age and CCT was determined. The associations between CH and CCT and between ORA and GAT IOPs, were investigated by linear regression analysis. The agreement between measuring devices was calculated. RESULTS. In the characterization study, P1 changed by 6.41 arbitrary units for every 1-mm Hg change in GAT IOP. CH (P1 P2) changed by 1.60 arbitrary units for every 1-mm Hg change in GAT IOP. For each unit change in P2, P1 changed by 1.27 units. From this association a new IOP-independent corneal factor was derived [P1 (P2/1.27)] and is termed the corneal constant factor (CCF; mm Hg). ORA IOP normalized for CCF was defined as P2 – CCF (mm Hg). The CCF (mm Hg) was associated with CCT (micrometers) and with age: CCF [(0.036 CCT) (0.028 age)] 1.06 (adjusted r 2 0.34; P 0.0001 for CCT, P 0.007 for age). Normalized ORA IOP measurements were not associated with CCT. GAT IOP was associated with CCT and CCF—more strongly with the latter: GAT IOP (0.03 CCT)1.52 (r 2 0.06, P 0.002); GAT IOP (0.65 CCF) 4.5 (r 2 0.13, P 0.0001). The mean difference (95% limits of agreement) between GAT and normalized ORA IOP was 0.1 (6.6 to 6.8) mm Hg. CONCLUSIONS. The CCF describes an IOP-independent biomechanical property of the cornea that increases with thicker CCT and decreases with greater age. It is moderately strongly associated with CCT and yet explains more of the interindividual variation in GAT IOP than does CCT. Normalized ORA IOP measurements are not associated with CCT. (Invest Ophthalmol Vis Sci. 2006;47:5337–5347) DOI:10.1167/iovs.060557

Work-Life ‘Balance’ in Europe:

Abstract: Although work-life ‘balance’ is an EU policy priority, within Europe there are considerable variations in the nature and extent of supports that national governments have offered to dual-earner fam...

Cultural Differences in Collaborative Authoring of Wikipedia

Abstract: This article explores the relationship between national culture and computer-mediated communication (CMC) in Wikipedia. The articles on the topic game from the French, German, Japanese, and Dutch Wikipedia websites were studied using content analysis methods. Correlations were investigated between patterns of contributions and the four dimensions of cultural influences proposed by Hofstede (Power Distance, Collectivism versus Individualism, Femininity versus Masculinity, and Uncertainty Avoidance). The analysis revealed cultural differences in the style of contributions across the cultures investigated, some of which are correlated with the dimensions identified by Hofstede. These findings suggest that cultural differences that are observed in the physical world also exist in the virtual world.

Dynamics of water droplets detached from porous surfaces of relevance to PEM fuel cells.

Abstract: The detachment of liquid droplets from porous material surfaces used with proton exchange membrane (PEM) fuel cells under the influence of a cross-flowing air is investigated computationally and experimentally. CCD images taken on a purpose-built transparent fuel cell have revealed that the water produced within the PEM is forming droplets on the surface of the gas-diffusion layer. These droplets are swept away if the velocity of the flowing air is above a critical value for a given droplet size. Static and dynamic contact angle measurements for three different carbon gas-diffusion layer materials obtained inside a transparent air-channel test model have been used as input to the numerical model; the latter is based on a Navier-Stokes equations flow solver incorporating the volume of fluid (VOF) two-phase flow methodology. Variable contact angle values around the gas-liquid-solid contact-line as well as their dynamic change during the droplet shape deformation process, have allowed estimation of the adhesion force between the liquid droplet and the solid surface and successful prediction of the separation line at which droplets loose their contact from the solid surface under the influence of the air stream flowing around them. Parametric studies highlight the relevant importance of various factors affecting the detachment of the liquid droplets from the solid surface.

Employment and the family : the reconfiguration of work and family life in contemporary societies

Abstract: Rates of employment amongst mothers of young children have risen rapidly in recent years. Attitudes to gender roles have changed, and both employers and governments have had to adjust to new realities. But some argue that recent changes in employment relations are making work more family 'unfriendly'. What are the real consequences of change? Rosemary Crompton explores the origins and background of this radical shift in the gendered division of labour. Topics covered include the changing attitudes to gender roles and family life, the gendered organisational context, and recent changes in employment relations and their impact on work-life articulation. A comparative analysis of Britain, France, Norway, Finland, the United States and Portugal provides an assessment of the varying impact of state policies, and the changing domestic division of labour. Crompton draws on original research and situates her findings within contemporary theoretical and empirical debates.

On flow-sensitive security types

Abstract: This article investigates formal properties of a family of semantically sound flow-sensitive type systems for tracking information flow in simple While programs. The family is indexed by the choice of flow lattice.By choosing the flow lattice to be the powerset of program variables, we obtain a system which, in a very strong sense, subsumes all other systems in the family (in particular, for each program, it provides a principal typing from which all others may be inferred). This distinguished system is shown to be equivalent to, though more simply described than, Amtoft and Banerjee's Hoare-style independence logic (SAS'04).In general, some lattices are more expressive than others. Despite this, we show that no type system in the family can give better results for a given choice of lattice than the type system for that lattice itself.Finally, for any program typeable in one of these systems, we show how to construct an equivalent program which is typeable in a simple flow-insensitive system. We argue that this general approach could be useful in a proof-carrying-code setting.

Daily activities and sleep quality in college students.

Abstract: There is growing evidence that social rhythms (e.g., daily activities such as getting into or out of bed, eating, and adhering to a work schedule) have important implications for sleep. The present...

Changing patterns of sexual behaviour in the era of highly active antiretroviral therapy.

Abstract: Purpose of reviewTo describe changing patterns of sexual behaviour in the era of highly active antiretroviral therapy among gay/bisexual men in Europe, Canada, USA and Australia.Recent findingsWhile there has been a substantial increase in high-risk sexual behaviour among gay men since 1996, this no

Is there a case for using visual analogue scale valuations in cost-utility analysis?

Abstract: This paper critically reviews theoretical and empirical propositions regarding visual analogue scale (VAS) valuations of health states and their use in cost-utility analysis (CUA). A widely repeated assertion in the economic evaluation literature is the inferiority, on theoretical grounds, of VAS valuations. Five common criticisms are: VAS lacks a theoretical foundation; VAS values are not 'choice based'; VAS values are not consistent with utility-under-uncertainty requirements; context and range effects observed in VAS valuation data mean that they cannot even be considered to represent measurable value functions; and when completing a VAS, people are not trying to express values. We address each of these points: the VAS does have a theoretical basis, being entirely consistent with the non-welfarist foundations of QALYs and CUA; the 'choiceless' nature of the VAS is incorrectly judged by stated preference criteria relevant to monetary rather than health state valuations, and VAS valuations do in any case involve an element of choice; because valuations are intended for use in social decision-making, it may be advantageous that VAS values are elicited under conditions of certainty; although there are measurement problems with the VAS, means such as better design and transformations of data can deal with these; and with any method of eliciting values, it is unrealistic to expect people consciously to think in terms of social science constructs such as utilities.Moreover, there are problems, both theoretical and empirical, with alternative methods. Selection of the appropriate valuation method should be based on empirical performance, and in this the VAS has important advantages. We conclude that there are strong grounds for disputing the consensus view against the VAS and challenge those who hold it to deploy more convincing arguments and evidence in favour of alternative methods. However, we identify areas where further research is required to establish and consolidate the potential of the VAS as a valuation method.

The Effect of Reporting Frequency on the Timeliness of Earnings: The Cases of Voluntary and Mandatory Interim Reports

Abstract: We examine whether financial reporting frequency affects the speed with which accounting information is reflected in security prices. For a sample of 28,824 reporting-frequency observations from 1950 to 1973, we find little evidence of differences in timeliness between firms reporting quarterly and those reporting semiannually, even after controlling for self-selection. However, firms that voluntarily increased reporting frequency from semiannual to quarterly experienced increased timeliness, while firms whose increase was mandated by the SEC did not. We conclude that there is little evidence to support the claim that regulation forcing firms to report more frequently improves earnings timeliness.

Longevity Bonds: Financial Engineering, Valuation, and Hedging

Abstract: This article examines the main characteristics of longevity bonds (LBs) and shows that they can take a large variety of forms which can vary enormously in their sensitivities to longevity shocks. We examine different ways of financially engineering LBs and consider problems arising from the dearth of ultra-long government bonds and the choice of the reference population index. The article also looks at valuation issues in an incomplete markets context and finishes with an examination of how LBs can be used as a risk management tool for hedging longevity risks.

Non-genetic and non-gestational parenthood: consequences for parent–child relationships and the psychological well-being of mothers, fathers and children at age 3

Abstract: BACKGROUND: Findings are presented of the third phase of a longitudinal study of children conceived by assisted reproduction procedures involving surrogacy and/or donor conception. METHODS: At the time of the child's third birthday, 34 surrogacy families, 41 donor insemination families and 41 oocyte donation families were compared with 67 natural conception families on standardized interview and questionnaire measures of the psychological well-being of the parents, mother-child relationships and the psychological well-being of the child. RESULTS: The differences found between family types reflected higher levels of warmth and interaction between mothers and their 3-year-old children in assisted reproduction families than in families with a naturally conceived child. A higher proportion of surrogacy parents than donor conception parents had told their children about the nature of their birth. CONCLUSIONS: It appears that the absence of a genetic and/or gestational link between parents and their child does not have a negative impact on parent-child relationships or the psychological well-being of mothers, fathers or children at age 3.

The Interrelationship Between Managerial Ownership and Board Structure

Abstract: The paper tests the hypothesis that high managerial ownership entrenches managers by allowing the CEO to create a board that is unlikely to monitor. The results show a strong negative relationship between the level of managerial ownership and corporate governance factors, such as, the split of the roles of the CEO and the Chairman, the proportion of non-executive directors, and the appointment of a non-executive director as a Chairman. I also find that companies with low managerial ownership are more likely to change their board structure to comply with the Cadbury (1992) recommendations. The results suggest that managers, through their high ownership, choose a board that is unlikely to monitor. Overall, the findings cast doubt on the effectiveness of the board as an internal corporate governance mechanism when managerial ownership is high.

Social support in people with chronic aphasia

Abstract: Background & Aims : Stroke and aphasia can have a profound impact on people's social activities, and family and social relationships. This study looked at patterns of social support in people with chronic aphasia following stroke. It examined the relationship between social support and quality of life, exploring which aspects of social support (social network versus perceived social support) were most associated with health-related quality of life (HRQL). Methods & Procedures : A cross-sectional interview-based survey study was conducted. A cluster-sampling framework was used to recruit participants with chronic aphasia following stroke (> 1 year) from three different sites in the south-east of England. Measures included the Stroke and Aphasia Quality of Life Scale-39 item version (SAQOL-39), the MOS Social Support Survey (SSS), and a social network questionnaire. Descriptive statistics, correlation, t -tests, and ANOVAs were used as appropriate. Outcomes & Results : The results of those able to self-r...

Momentum Strategies in Commodity Futures Markets

Abstract: The article tests for the presence of short-term continuation and long-term reversal in commodity futures prices. While contrarian strategies do not work, the article identifies 13 profitable momentum strategies that generate 9.38% average return a year. A closer analysis of the constituents of the long-short portfolios reveals that the momentum strategies buy backwardated contracts and sell contangoed contracts. The correlation between the momentum returns and the returns of traditional asset classes is also found to be low, making the commodity-based relative-strength portfolios excellent candidates for inclusion in well-diversified portfolios.

Safety and efficacy of the cyclooxygenase-2 inhibitors parecoxib and valdecoxib after noncardiac surgery.

Abstract: Background:Valdecoxib and its intravenous prodrug parecoxib are reported to increase thromboembolic risk after coronary artery bypass grafting. The authors conducted a randomized trial to examine their safety and analgesic efficacy in patients recovering from major noncardiac surgical procedures.Met

Advantages of binocular vision for the control of reaching and grasping.

Abstract: Theoretical considerations suggest that binocular information should provide advantages, compared to monocular viewing, for the planning and execution of natural reaching and grasping actions, but empirical support for this is quite equivocal. We have examined these predictions on a simple prehension task in which normal subjects reached, grasped and lifted isolated cylindrical household objects (two sizes, four locations) in a well-lit environment, using binocular vision or with one eye occluded. Various kinematic measures reflecting the programming and on-line control of the movements were quantified, in combination with analyses of different types of error occurring in the velocity, spatial path and grip aperture profiles of each trial. There was little consistent effect of viewing condition on the early phase of the reach, up to and including the peak deceleration, but all other aspects of performance were superior under binocular control. Subjects adopted a cautious approach when binocular information was unavailable: they extended the end phase of the reach and pre-shaped their hand with a wider grip aperture further away from the object. Despite these precautions, initial grip application was poorly coordinated with target contact and was inaccurately scaled to the objects’ dimensions, with the subsequent post-contact phase of the grasp significantly more prolonged, error-prone and variable compared to binocular performance. These effects were obtained in two separate experiments in which the participants’ performed the task under randomized or more predictable (blocked) viewing conditions. Our data suggest that binocular vision offers particular advantages for controlling the terminal reach and the grasp. We argue that these benefits derive from binocular disparity processing linked to changes in relative hand–target distance, and that this depth information is independently used to regulate the progress of the approaching hand and to guide the digits to the (pre-selected) contact points on the object, thereby ensuring that the grip is securely applied.

Nonlinearity in Deviations from Uncovered Interest Parity: An Explanation of the Forward Bias Puzzle

Abstract: We provide empirical evidence that deviations from the uncovered interest rate parity (UIP) condition display significant nonlinearities, consistent with theories based on transactions costs or limits to speculation. This evidence suggests that the forward bias documented in the literature may be less indicative of major market inefficiencies than previously thought. Monte Carlo experiments allow us to reconcile these results with the large empirical literature on the forward bias puzzle since we show that, if the true process of UIP deviations were of the nonlinear form we consider, estimation of conventional spot-forward regressions would generate the anomalies documented in previous research.

Transmission loss reduction based on FACTS and bacteria foraging algorithm

Abstract: An optimal location and parameters of an UPFC along with values of OLTC taps are tuned with a view to minimize the real power losses of a mesh power network. This issue is formulated as a non-linear equality and inequality constrained optimization problem with an objective function incorporating power loss. A new evolutionary algorithm known as Bacteria Foraging is applied for solving, the optimum location and the amount of series injected voltage for the UPFC, and the best values of the taps present in the system. The same problem is also solved with Interior Point Successive Linearization technique using the LINPROG command of MATLAB. A comparison between the two suggests the superiority of the proposed algorithm.

Comparable fMRI activity with differential behavioural performance on mental rotation and overt verbal fluency tasks in healthy men and women

Abstract: To explicate the neural correlates of sex differences in visuospatial and verbal fluency tasks, we examined behavioural performance and blood-oxygenation-level-dependent (BOLD) regional brain activity, using functional magnetic resonance imaging, during a three-dimensional (3D) mental rotation task and a compressed sequence overt verbal fluency task in a group of healthy men (n=9) and women (n=10; tested during the low-oestrogen phase of the menstrual cycle). Men outperformed women on the mental rotation task, and women outperformed men on the verbal fluency task. For the mental rotation task, men and women activated areas in the right superior parietal lobe and the bilateral middle occipital gyrus in association with the rotation condition. In addition, men activated the left middle temporal gyrus and the right angular gyrus. For verbal fluency, men activated areas in the bilateral superior frontal gyrus, right cingulate gyrus, left precentral gyrus, left medial frontal gyrus, left inferior frontal gyrus, thalamus, left parahippocampal gyrus and bilateral lingual gyrus, and women activated areas in the bilateral inferior frontal gyrus and left caudate. Despite observing task related activation in the hypothesised areas in men and women, no areas significantly differentiated the two sexes. Our results demonstrate comparable brain activation in men and women in association with mental rotation and verbal fluency function with differential performance, and provide support for sex differences in brain–behaviour relationships.

Sex and the Internet: gay men, risk reduction and serostatus.

Abstract: Access to the Internet has increased dramatically over the past decade as has its use for meeting sexual partners (e-dating), particularly among gay men. Between June 2002 and January 2004, 128 gay/ bisexual men living in London were interviewed one-to-one about their experience of e-dating, sexual risk and HIV prevention. The men were recruited both online (through the Internet) and offline (in clinics and the community); 32 men were HIV-positive, 59 HIV-negative, while 13 had never had an HIV test. A key finding was that both identity as well as anonymity are vital to e-dating. Through a process of online filtering and sero-sorting, HIV-positive men are able to meet other positive men for anal sex without condoms. While this does not present a risk of HIV transmission to an uninfected person it does have implications for the potential transmission of other STIs such as syphilis and LGV. Through e-dating, HIV-positive gay men can also avoid abuse, discrimination and sexual rejection. Our findings do not support the suggestion that the attraction of e-dating is that it affords absolute anonymity. We found that the gradual expression of identity is vital for e-dating among gay men. Internet-based HIV prevention campaigns need to take account of the different ways in which gay reflexively manage aspects of their identity online

The Socially Responsible Existentialist: A Normative Emphasis for Journalists in a New Media Environment

Abstract: In an open and virtually boundless media environment, old responses to the question of who is a journalist, based primarily on roles associated with the process of gathering and disseminating information, no longer apply. This article suggests a reconceptualization of the journalist based instead on normative constructs. Specifically, it advocates a blend of two competing philosophical approaches, existentialism and social responsibility theory, as well as two roughly corresponding professional norms, independence and accountability. The combination produces a “socially responsible existentialist”, a journalist who chooses to act as a trustworthy source of information that serves the public interest. That framework is applied at both a concrete level, through consideration of weblogs and the proliferation of partisan information sources, and a conceptual level, through consideration of gatekeeping and agenda-setting functions.

Perspectives of Quality of Life by People with Aphasia and Their Family: Suggestions for Successful Living

Abstract: Understanding the client's perspective is essential for good practitioner care in rehabilitation after stroke, and nothing is more relevant than enquiring directly about our clients' quality of life to inform our management. Relatively little is known about how older people with aphasia consider the quality of their current lives, and this article seeks to explore this issue. Four women's accounts of their life quality are presented, as well as their husbands' or daughter's accounts of their lives. Their stories share some common elements. Who you love or share your life with; where you live; feeling independent and/or in control; and engaging in satisfying activities mattered to these women's life quality. The impact of aphasia varies across the cases, and the need to accept change for successful living is illustrated in all accounts.