System model development for nuclear thermal propulsion

A critical enabling technology in the evolutionary development of nuclear thermal propulsion (NTP) is the ability to predict the system performance under a variety of operating conditions. This is crucial for mission analysis and for control subsystem testing as well as for the modeling of various failure modes. Performance must be accurately predicted during steady-state and transient operation, including startup, shutdown, and post operation cooling. The development and application of verified and validated system models has the potential to reduce the design, testing, and cost and time required for the technology to reach flight-ready status. Since Oct. 1991, the U.S. Department of Energy (DOE), Department of Defense (DOD), and NASA have initiated critical technology development efforts for NTP systems to be used on Space Exploration Initiative (SEI) missions to the Moon and Mars. This paper presents the strategy and progress of an interagency NASA/DOE/DOD team for NTP system modeling. It is the intent of the interagency team to develop several levels of computer programs to simulate various NTP systems. The first level will provide rapid, parameterized calculations of overall system performance. Succeeding computer programs will provide analysis of each component in sufficient detail to guide the design teams and experimental efforts. The computer programs will allow simulation of the entire system to allow prediction of the integrated performance. An interagency team was formed for this task to use the best capabilities available and to assure appropriate peer review

Untangling the Conceptual Isssues Raised in Reydon and Scholz’s Critique of Organizational Ecology and Darwinian Populations

Reydon and Scholz raise doubts about the Darwinian status of organizational ecology by arguing that Darwinian principles are not applicable to organizational populations. Although their critique of organizational ecology’s typological essentialism is correct, they go on to reject the Darwinian status of organizational populations. This paper claims that the distinction between replicators and interactors, raised in modern philosophy of biology but not discussed by Reydon and Scholz, points the way forward for organizational ecologists. It is possible to conceptualise evolving Darwinian populations providing the inheritance mechanism is appropriately specified. By this approach, adaptation and selection are no longer dichotomised, and the evolutionary significance of knowledge transmission is highlightedPeer reviewe

Genome-wide meta-analysis identified novel variant associated with hallux valgus in Caucasians

Background: Hallux valgus, one of the most common structural foot deformities, is highly heritable. However, previous efforts to elucidate the genetic underpinnings of hallux valgus through a genome-wide association study (GWAS) conducted in 4409 Caucasians did not identify genome-wide significant associations with hallux valgus in both gender-specific and sex-combined GWAS meta-analyses. In this analysis, we add newly available data and more densely imputed genotypes to identify novel genetic variants associated with hallux valgus. Methods: A total of 5925 individuals of European Ancestry were categorized into two groups: 'hallux valgus present' (n = 2314) or 'no deformity' (n = 3611) as determined by trained examiners or using the Manchester grading scale. Genotyping was performed using commercially available arrays followed by imputation to the Haplotype Reference Consortium (HRC) reference panel version 1.1. We conducted both sex-specific and sex-combined association analyses using logistic regression and generalized estimating equations as appropriate in each cohort. Results were then combined in a fixed-effects inverse-variance meta-analyses. Functional Mapping and Annotation web-based platform (FUMA) was used for positional mapping, gene and gene-set analyses. Results: We identified a novel locus in the intronic region of CLCA2 on chromosome 1, rs55807512 (OR = 0.48, p = 2.96E-09), an expression quantitative trait locus for COL24A1, a member of the collagen gene family. Conclusion: In this report of the largest GWAS of hallux valgus to date, we identified a novel genome-wide significant locus for hallux valgus. Additional replication and functional follow-up will be needed to determine the functional role of this locus in hallux valgus biology

Case-mix and the use of control charts in monitoring mortality rates after coronary artery bypass

BACKGROUND: There is debate about the role of crude mortality rates and case-mix adjusted mortality rates in monitoring the outcomes of treatment. In the context of quality improvement a key purpose of monitoring is to identify special cause variation as this type of variation should be investigated to identify possible causes. This paper investigates agreement between the identification of special cause variation in risk adjusted and observed hospital specific mortality rates after coronary artery bypass grafting in New York hospitals. METHODS: Coronary artery bypass grafting mortality rates between 1994 and 2003 were obtained from the New York State Department of Health's cardiovascular reports for 41 hospitals. Cross-sectional control charts of crude (observed) and risk adjusted mortality rates were produced for each year. Special cause variation was defined as a data point beyond the 99.9% probability limits: hospitals showing special cause variation were identified for each year. Longitudinal control charts of crude (observed) and risk adjusted mortality rates were produced for each hospital with data for all ten years (n = 27). Special cause variation was defined as a data point beyond 99.9% probability limits, two out of three consecutive data points beyond 95% probability limits (two standard deviations from the mean) or a run of five consecutive points on one side of the mean. Years showing special cause variation in mortality were identified for each hospital. Cohen's Kappa was calculated for agreement between special causes identified in crude and risk-adjusted control charts. RESULTS: In cross sectional analysis the Cohen's Kappa was 0.54 (95% confidence interval: 0.28 to 0.78), indicating moderate agreement between the crude and risk-adjusted control charts with sensitivity 0.4 (95% confidence interval 0.17–0.69) and specificity 0.98 (95% confidence interval: 0.95–0.99). In longitudinal analysis, the Cohen's Kappa was 0.61 (95% confidence interval: 0.39 to 0.83) indicating good agreement between the tests with sensitivity 0.63 (95% confidence interval: 0.39–0.82) and specificity 0.98 (95% confidence interval: 0.96 to 0.99). CONCLUSION: There is moderate-good agreement between signals of special cause variation between observed and risk-adjusted mortality. Analysis of observed hospital specific CABG mortality over time and with other hospitals appears to be useful in identifying special causes of variation. Case-mix adjustment may not be essential for longitudinal monitoring of outcomes using control charts

Gender specific age-related changes in bone density, muscle strength and functional performance in the elderly: a-10 year prospective population-based study

Background:&nbsp;Age-related losses in bone mineral density (BMD), muscle strength, balance, and gait have been linked to&nbsp;an increased risk of falls, fractures and disability, but few prospective studies have compared the timing, rate and pattern&nbsp;of changes in each of these measures in middle-aged and older men and women. This is important so that targeted&nbsp;strategies can be developed to optimise specific musculoskeletal and functional performance measures in older adults.&nbsp;Thus, the aim of this 10-year prospective study was to: 1) characterize and compare age- and gender-specific changes in&nbsp;BMD, grip strength, balance and gait in adults aged 50 years and over, and 2) compare the relative rates of changes&nbsp;between each of these musculoskeletal and functional parameters with ageing.Methods: Men (n = 152) and women (n = 206) aged 50, 60, 70 and 80 years recruited for a population-based study had&nbsp;forearm BMD, grip strength, balance and gait velocity re-assessed after 10-years.Results: The annual loss in BMD was 0.5-0.7% greater in women compared to men aged 60 years and older&nbsp;(p &lt; 0.05- &lt; 0.001), but there were no gender differences in the rate of loss in grip strength, balance or gait. From the age&nbsp;of 50 years there was a consistent pattern of loss in grip strength, while the greatest deterioration in balance and gait&nbsp;occurred from 60 and 70 years onwards, respectively. Comparison of the changes between the different measures&nbsp;revealed that the annual loss in grip strength in men and women aged &lt;70 years was 1-3% greater than the decline in&nbsp;BMD, balance and gait velocity.Conclusion: There were no gender differences in the timing (age) and rate (magnitude) of decline in grip strength,&nbsp;balance or gait in Swedish adults aged 50 years and older, but forearm BMD decreased at a greater rate in women than&nbsp;in men. Furthermore, there was heterogeneity in the rate of loss between the different musculoskeletal and function&nbsp;parameters, especially prior to the age of 70 years, with grip strength deteriorating at a greater rate than BMD,&nbsp;balance and gait.</div

Organization, Evolution, Cognition and Dynamic Capabilities

Using insights from ‘embodied cognition’ and a resulting ‘cognitive theory of the firm’, I aim to contribute to the further development of evolutionary theory of organizations, in the specification of organizations as ‘interactors’ that carry organizational competencies as ‘replicators’, within industries as ‘populations’. Especially, I analyze how, if at all, ‘dynamic capabilities’ can be fitted into evolutionary theory. I propose that the prime purpose of an organization is to serve as a cognitive ‘focusing device’. Here, cognition has a wide meaning, including perception, interpretation, sense making, and value judgements. I analyse how this yields organizations as cohesive wholes, and differences within and between industries. I propose the following sources of variation: replication in communication, novel combinations of existing knowledge, and a path of discovery by which exploitation leads to exploration. These yield a proposal for dynamic capabilities. I discuss in what sense, and to what extent these sources of variation are ‘blind’, as postulated in evolutionary theory.

Vertical integration for full outsourcing: growth and internationalization of a portuguese packaging firm

Based on a case study of a Portuguese packaging firm, this paper examines how vertical integration of the supplier serves as a vehicle for the full outsourcing of the client firms' needs in a solution that reduces transaction costs, favors specialization, and permits small and mediumsized firms to develop competencies that may be exploited in a wide array of projects. Vertical integration by the supplier (a governance decision) is a strategic response to changes in the sourcing model of the clients. Client-supplier relationships have inter-spatial and inter-temporal value that surpasses spot market exchanges

The Past and Future of Evolutionary Economics : Some Reflections Based on New Bibliometric Evidence

This document is the Accepted Manuscript version of the following article: Geoffrey M. Hodgson, and Juha-Antti Lamberg, ‘The past and future of evolutionary economics: some reflections based on new bibliometric evidence’, Evolutionary and Institutional Economics Review, first online 20 June 2016. The final publication is available at Springer via doi: http://dx.doi.org/10.1007/s40844-016-0044-3 © Japan Association for Evolutionary Economics 2016The modern wave of ‘evolutionary economics’ was launched with the classic study by Richard Nelson and Sidney Winter (1982). This paper reports a broad bibliometric analysis of ‘evolutionary’ research in the disciplines of management, business, economics, and sociology over 25 years from 1986 to 2010. It confirms that Nelson and Winter (1982) is an enduring nodal reference point for this broad field. The bibliometric evidence suggests that ‘evolutionary economics’ has benefitted from the rise of business schools and other interdisciplinary institutions, which have provided a home for evolutionary terminology, but it has failed to nurture a strong unifying core narrative or theory, which in turn could provide superior answers to important questions. This bibliometric evidence also shows that no strong cluster of general theoretical research immediately around Nelson and Winter (1982) has subsequently emerged. It identifies developmental problems in a partly successful but fragmented field. Future research in ‘evolutionary economics’ needs a more integrated research community with shared conceptual narratives and common research questions, to promote conversation and synergy between diverse clusters of research.Peer reviewedFinal Accepted Versio

Characteristics of optimum falls prevention exercise programmes for community-dwelling older adults using the FITT principle

peer-reviewedThis review aims to identify the optimal exercise intervention characteristics for falls prevention among community-dwelling adults aged 60 years and over. Articles for inclusion were sourced by searching the Academic Search Premier, AMED, Biomedical Reference Collection: Expanded, CINAHL Plus, MEDLINE and SPORTDiscus databases with the key words ‘falls’, ‘prevention’, ‘exercise’ and ‘community’ and via reference lists of relevant articles. Only articles of level 1 or level 2 evidence (Howick et al. 2011) were included. Other inclusion criteria included recording falls incidence as an outcome measure, examining a community-dwelling population aged 60 years or over and implementing exercise as a single intervention in at least one group. Exercise programme characteristics from 31 articles were examined according to their frequency, intensity, time and type and their effects on falls incidence were reviewed. Exercising for a minimum of 1 h/week for at least 40 h over the course of an intervention is required to successfully reduce falls incidence. The optimal exercise frequency is three times per week, but the optimal duration per bout remains unclear. Specific balance training of sufficiently challenging intensity is a vital programme component, and strength training is most effective when combined with balance training. Flexibility and endurance training may also be included as part of a comprehensive programme. A combination of group and individual home exercise may be most effective for preventing falls and promoting exercise adherence