156 research outputs found

    Vortical and Wave Modes in 3D Rotating Stratified Flows: Random Large Scale Forcing

    Full text link
    Utilizing an eigenfunction decomposition, we study the growth and spectra of energy in the vortical and wave modes of a 3D rotating stratified fluid as a function of ϵ=f/N\epsilon = f/N. Working in regimes characterized by moderate Burger numbers, i.e. Bu=1/ϵ2<1Bu = 1/\epsilon^2 < 1 or Bu1Bu \ge 1, our results indicate profound change in the character of vortical and wave mode interactions with respect to Bu=1Bu = 1. As with the reference state of ϵ=1\epsilon=1, for ϵ<1\epsilon < 1 the wave mode energy saturates quite quickly and the ensuing forward cascade continues to act as an efficient means of dissipating ageostrophic energy. Further, these saturated spectra steepen as ϵ\epsilon decreases: we see a shift from k1k^{-1} to k5/3k^{-5/3} scaling for kf<k<kdk_f < k < k_d (where kfk_f and kdk_d are the forcing and dissipation scales, respectively). On the other hand, when ϵ>1\epsilon > 1 the wave mode energy never saturates and comes to dominate the total energy in the system. In fact, in a sense the wave modes behave in an asymmetric manner about ϵ=1\epsilon = 1. With regard to the vortical modes, for ϵ1\epsilon \le 1, the signatures of 3D quasigeostrophy are clearly evident. Specifically, we see a k3k^{-3} scaling for kf<k<kdk_f < k < k_d and, in accord with an inverse transfer of energy, the vortical mode energy never saturates but rather increases for all k<kfk < k_f. In contrast, for ϵ>1\epsilon > 1 and increasing, the vortical modes contain a progressively smaller fraction of the total energy indicating that the 3D quasigeostrophic subsystem plays an energetically smaller role in the overall dynamics.Comment: 18 pages, 6 figs. (abbreviated abstract

    A prospective survey of the outcome of pregnancy in a rural area of the Gambia.

    Get PDF
    The outcome of pregnancy was studied in 672 women over a 1-year period in a rural area of the Gambia where medical resources were very limited, prior to the introduction of a primary health care programme. Maternal mortality was very high (22 per 1000), mainly caused by postpartum haemorrhage and infections. Stillbirth and neonatal death rates were also high (35 and 65 per 1000, respectively); prematurity and infections were the main causes of death in neonates. First or late pregnancies, ages under 20 or over 40 years, and multiple pregnancies were all associated with a poor outcome of pregnancy. Women in these groups should therefore be encouraged by traditional birth attendants and by the staff of rural antenatal clinics to deliver in a health centre or hospital

    Utility of the Health of the Nation Outcome Scales (HoNOS) in Predicting Mental Health Service Costs for Patients with Common Mental Health Problems : Historical Cohort Study

    Get PDF
    BACKGROUND: Few countries have made much progress in implementing transparent and efficient systems for the allocation of mental health care resources. In England there are ongoing efforts by the National Health Service (NHS) to develop mental health 'payment by results' (PbR). The system depends on the ability of patient 'clusters' derived from the Health of the Nation Outcome Scales (HoNOS) to predict costs. We therefore investigated the associations of individual HoNOS items and the Total HoNOS score at baseline with mental health service costs at one year follow-up.METHODS: An historical cohort study using secondary care patient records from the UK financial year 2012-2013. Included were 1,343 patients with 'common mental health problems', represented by ICD-10 disorders between F32-48. Costs were based on patient contacts with community-based and hospital-based mental health services. The costs outcome was transformed into 'high costs' vs 'regular costs' in main analyses.RESULTS: After adjustment for covariates, 11 HoNOS items were not associated with costs. The exception was 'self-injury' with an odds ratio of 1.41 (95% CI 1.10-2.99). Population attributable fractions (PAFs) for the contribution of HoNOS items to high costs ranged from 0.6% (physical illness) to 22.4% (self-injury). After adjustment, the Total HoNOS score was not associated with costs (OR 1.03, 95% CI 0.99-1.07). However, the PAF (33.3%) demonstrated that it might account for a modest proportion of the incidence of high costs.CONCLUSIONS: Our findings provide limited support for the utility of the self-injury item and Total HoNOS score in predicting costs. However, the absence of associations for the remaining HoNOS items indicates that current PbR clusters have minimal ability to predict costs, so potentially contributing to a misallocation of NHS resources across England. The findings may inform the development of mental health payment systems internationally, especially since the vast majority of countries have not progressed past the early stages of this development. Discrepancies between our findings with those from Australia and New Zealand point to the need for further international investigations

    Mapping species distributions: A comparison of skilled naturalist and lay citizen science recording

    Get PDF
    To assess the ability of traditional biological recording schemes and lay citizen science approaches to gather data on species distributions and changes therein, we examined bumblebee records from the UK’s national repository (National Biodiversity Network) and from BeeWatch. The two recording approaches revealed similar relative abundances of bumblebee species but different geographical distributions. For the widespread common carder (Bombus pascuorum), traditional recording scheme data were patchy, both spatially and temporally, reflecting active record centre rather than species distribution. Lay citizen science records displayed more extensive geographic coverage, reflecting human population density, thus offering better opportunities to account for recording effort. For the rapidly spreading tree bumblebee (Bombus hypnorum), both recording approaches revealed similar distributions due to a dedicated mapping project which overcame the patchy nature of naturalist records. We recommend, where possible, complementing skilled naturalist recording with lay citizen science programmes to obtain a nation-wide capability, and stress the need for timely uploading of data to the national repository

    Institutions, Human Capital, and Development

    Get PDF
    In this article, we revisit the relationship among institutions, human capital, and development. We argue that empirical models that treat institutions and human capital as exogenous are misspecified, both because of the usual omitted variable bias problems and because of differential measurement error in these variables, and that this misspecification is at the root of the very large returns of human capital, about four to five times greater than that implied by micro (Mincerian) estimates, found in the previous literature. Using cross-country and cross-regional regressions, we show that when we focus on historically determined differences in human capital and control for the effect of institutions, the impact of institutions on long-run development is robust, whereas the estimates of the effect of human capital are much diminished and become consistent with micro estimates. Using historical and cross-country regression evidence, we also show that there is no support for the view that differences in the human capital endowments of early European colonists have been a major factor in the subsequent institutional development of former colonies.Comisión Nacional de Investigación Ciencia y Tecnología (Chile) (CONICYT/Programa de Investigación Asociativa (project SOC1102))United States. Army Research Office (ARO MURI W911NF-12-1-0509

    Stranded research? Leading finance journals are silent on climate change

    Get PDF
    Finance research has shaped the modern financial system, influencing investors and market participants directly through research findings and indirectly through teaching and training programmes. Climate change presents major risks to the global financial system as well as new opportunities for investors. Is climate finance an important topic in finance research? We systematically analyse the content of 20,725 articles published in the leading 21 finance journals between January 1998 and June 2015. We find that only 12 articles (0.06%) are related in some way to climate finance. The three elite finance journals (Journal of Finance, Journal of Financial Economics and Review of Financial Studies) did not publish a single article related to climate finance over the 17.5-year period. We repeat our analysis across a sample of 29 elite business journals spanning accounting, economics, management, marketing and operations research, as well as finance. We find a similar dearth of published climate finance research. We consider four possible explanations for this failure of top finance and business journals to engage with climate finance as a research topic. These include methodological constraints and editorial policies. We conclude by arguing why it is critical for climate-related research to be given greater attention and prominence in finance journals

    Rapid assessment of injection practices in Cambodia, 2002

    Get PDF
    BACKGROUND: Injection overuse and unsafe injection practices facilitate transmission of bloodborne pathogens such as hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Anecdotal reports of unsafe and unnecessary therapeutic injections and the high prevalence of HBV (8.0%), HCV (6.5%), and HIV (2.6%) infection in Cambodia have raised concern over injection safety. To estimate the magnitude and patterns of such practices, a rapid assessment of injection practices was conducted. METHODS: We surveyed a random sample of the general population in Takeo Province and convenience samples of prescribers and injection providers in Takeo Province and Phnom Penh city regarding injection-related knowledge, attitudes, and practices. Injection providers were observed administering injections. Data were collected using standardized methods adapted from the World Health Organization safe injection assessment guidelines. RESULTS: Among the general population sample (n = 500), the overall injection rate was 5.9 injections per person-year, with 40% of participants reporting receipt of ≥ 1 injection during the previous 6 months. Therapeutic injections, intravenous infusions, and immunizations accounted for 74%, 16% and 10% of injections, respectively. The majority (>85%) of injections were received in the private sector. All participants who recalled their last injection reported the injection was administered with a newly opened disposable syringe and needle. Prescribers (n = 60) reported that 47% of the total prescriptions they wrote included a therapeutic injection or infusion. Among injection providers (n = 60), 58% recapped the syringe after use and 13% did not dispose of the used needle and syringe appropriately. Over half (53%) of the providers reported a needlestick injury during the previous 12 months. Ninety percent of prescribers and injection providers were aware HBV, HCV, and HIV were transmitted through unsafe injection practices. Knowledge of HIV transmission through "dirty" syringes among the general population was also high (95%). CONCLUSION: Our data suggest that Cambodia has one of the world's highest rates of overall injection usage, despite general awareness of associated infection risks. Although there was little evidence of reuse of needles and syringes, support is needed for interventions to address injection overuse, healthcare worker safety and appropriate waste disposal

    Orthodontic treatment needs in the western region of Saudi Arabia: a research report

    Get PDF
    BACKGROUND: Evaluation of self perceived and actual need for orthodontic treatment helps in planning orthodontic services and estimating the required resources and man power. In the present study, the perceptive need as evaluated by patients and the actual need to orthodontic treatment, as assessed by orthodontists, were evaluated at two types of dental practices in the city of Jeddah using the Index of Orthodontic Treatment Need (IOTN). METHODS: A consecutive sample of 743 adults seeking orthodontic treatment at two different types of dental practices in Jeddah; King Abdulaziz University, Faculty of Dentistry (KAAU) (Free treatment) and two private dental polyclinics (PDP) (Paid treatment), was examined for orthodontic treatment need using the dental health component (DHC) of the IOTN. The self-perceived need for orthodontic treatment was also determined using the aesthetic component (AC) of the IOTN. The IOTN score and the incidence of each variable were calculated statistically. AC and DHC categories were compared using the Chi-Square and a correlation between them was assessed using Spearman's correlation test. AC and DHC were also compared between the two types of dental practices using the Chi-Square. RESULTS: The results revealed that among the 743 patients studied, 60.6% expressed no or slight need for treatment, 23.3% expressed moderate to borderline need and only16.1% thought they needed orthodontic treatment. Comparing these estimates to professional judgments, only 15.2% conformed to little or no need for treatment, 13.2% were assessed as in borderline need and 71.6% were assessed as in need for treatment (p < 0.001). Spearman's correlation test proved no correlation (r = -.045) between the two components. Comparing the AC and the DHC between the KAAU group and PDP group showed significant differences between the two groups (p < 0.001). CONCLUSION: Patient's perception to orthodontic treatment does not always correlate with professional assessment. The IOTN is a valid screening tool that should be used in orthodontic clinics for better services especially, in health centers that provide free treatment

    Dynamics of Wind Setdown at Suez and the Eastern Nile Delta

    Get PDF
    BACKGROUND: Wind setdown is the drop in water level caused by wind stress acting on the surface of a body of water for an extended period of time. As the wind blows, water recedes from the upwind shore and exposes terrain that was formerly underwater. Previous researchers have suggested wind setdown as a possible hydrodynamic explanation for Moses crossing the Red Sea, as described in Exodus 14. METHODOLOGY/PRINCIPAL FINDINGS: This study analyzes the hydrodynamic mechanism proposed by earlier studies, focusing on the time needed to reach a steady-state solution. In addition, the authors investigate a site in the eastern Nile delta, where the ancient Pelusiac branch of the Nile once flowed into a coastal lagoon then known as the Lake of Tanis. We conduct a satellite and modeling survey to analyze this location, using geological evidence of the ancient bathymetry and a historical description of a strong wind event in 1882. A suite of model experiments are performed to demonstrate a new hydrodynamic mechanism that can cause an angular body of water to divide under wind stress, and to test the behavior of our study location and reconstructed topography. CONCLUSIONS/SIGNIFICANCE: Under a uniform 28 m/s easterly wind forcing in the reconstructed model basin, the ocean model produces an area of exposed mud flats where the river mouth opens into the lake. This land bridge is 3-4 km long and 5 km wide, and it remains open for 4 hours. Model results indicate that navigation in shallow-water harbors can be significantly curtailed by wind setdown when strong winds blow offshore
    corecore