Numerical Computation of Flapping-Wing Propulsion and Power Extraction

AIAA Paper No. 97-0826, 35th AIAA Aerospace Sciences Meeting, Reno, Nevada, Jan. 1997.Numerical procedures are presented for the systematic computation of unsteady flows over moving airfoils or airfoil combinations, and these procedures are applied to the investigation of flapping-wing propulsion and power extraction. Flow solutions about single foils are computed using an unsteady, two-dimensional panel code coupled with a boundary layer algorithm and driven using an interactive graphical user interface. Flow solutions about airfoil combinations are computed using a companion, multi-element version of the panel code. Results for pitching-only and plunging-only motions compare favorably with theory and reasonably well with experimental results. Extensive computations are performed over the broad parameter space for combined pitching and plunging motions using the foil as both a propulsive device and as a wingmill or power-extraction device. Results modeling flight in ground effect are compared with other numerical and experimental results

An Investigation of the Fluid-Structure Interaction in an Oscillating-Wing Micro-Hydropower Generator

in Fluid Structure Interaction II, Eds. Chakrabarti, S.K., Brebbia, C.A., Almorza, D. and Gonzalez-Palma, R., WIT Press, Southampton, UK, 2003, pp. 73-82.Results of a computational and experimental investigation of the fluid-structure phenomena occurring in an oscillating-wing micro-hydropower generator are presented. The generator consists of tandem wings which oscillate in a combined pitch-plunge mode with approximately 90 degree phase angle between the two motions. Two-dimensional inviscid and viscous flow codes are used to predict the oscillatory flow field and the power transferred from the water flow to the oscillating wings. Experimental results of water tunnel tests of this hydropower generator are also described and comparisons between the measured and predicted power output are given

PMTCT from research to reality - results from a routine service

Objectives. Assessment of the efficacy of a prevention of mother-to-child transmission (PMTCT) programme in a routine service setting in comparison to a research environment.Design. Descriptive study over a 13-month period utilising retrospective data obtained from hospital records complemented by prospective data on a sample of patients enrolled in a study to determine an affordable HIV diagnostic protocol for infants.Setting. Routine PMTCT service at Coronation Women and Children's Hospital (CWCH) situated in Johannesburg and affiliated to the University of the Witwatersrand.Subjects. Pregnant women known to be HIV infected who delivered at CWCH from 1 October 2001 to 31 October 2002.Outcome measures. The HIV transmission rate to infants, which reflects nevirapine (NVP) delivery and infant feeding practices, and follow-up rates of perinatally exposed children.Results. Of the 8 221 deliveries, 1 234 (15%) occurred in women known to be HIV infected, HIV transmission rates of 8.7% at 6 weeks and 8.9% at 3 months of age in the study population verifies the high rate of NVP administration and the ability of women to formula-feed their babies and abstain from breast-feeding. More than one-third of infants never return for follow-up and more than 70% are lost to follow-up by 4 months of age.Conclusions. The low HIV transmission rate confirms the efficacy of this routine service PMTCT programme. HIV infected children are not being identified for medical management as part of PMTCT follow-up. It is imperativethat record keeping is improved to facilitate ongoing monitoring

Genetic testing reveals some mislabeling but general compliance with a ban on herbivorous fish harvesting in Belize

Overfishing of herbivorous fishes is one of the primary causes of Caribbean coral reef decline. In Belize, herbivorous fishes comprised 28% of the catch from 2005 to 2008. In 2009, the Belize Fisheries Department implemented a national ban on herbivorous fish harvesting to mitigate high-macroalgal cover on much of the Belize Barrier Reef. However, compliance with this approach has not been evaluated. We assessed the proportion of herbivorous fish in local markets by genetically identifying fish fillets sold in five major towns in Belize from 2009 to 2011. We found that 5-7% of 111 fillets were identified as herbivorous fish and 32-51% were mislabeled. A 5-7% proportion of parrotfish in local markets suggests some ongoing parrotfish harvesting. However, our results suggest that the ban has reduced herbivorous fish harvesting and has the potential to help facilitate the restoration of coral reef ecosystems

Is tissue engineering of the TMJ disc a feasible process?

Temporomandibular joint (TMJ) disorders are common and difficult to remedy. Tissue engineering is one alternative that seeks to improve TMJ sugical treatment options. Tissue engineering aims to replace diseased or injured tissue with biologically engineered constructs. These constructs should reproduce native function and limit an immune response. To achieve tissue engineering success, it is important to first understand the tissue's cellular, biochemical and mechanical properties in order to create validation and design criteria. Reviewd herein are the known properties of the TMJ disc and initial attempts toward TMJ disc tissue engineering. Important aspects of tissue engineering are scaffold selection, cell source, biochemical factors, and mechanical stimuli

A study of smoke formation from wood combustion

Aerosol time of flight mass spectrometry (ATOFMS) was used to analyse the particles emitted during the flaming and smouldering phases of the combustion of samples of hard and soft woods. Eugenol and furfural were also burned and using results from previous work of the authors, they have been shown to be useful proxies for initial wood combustion products. The ratios of elementary carbon to total carbon in the particles were similar for both the woods and for eugenol. The ATOFMS spectra of most of the particles were consistent with the presence of soot precursor constituents along with oxygen containing fragments. Most particle diameters were less than 2.5. μm, with the greatest concentration of <. 0.12. μm

Satisfactory cross cultural equivalence of the Dutch WOMAC in patients with hip osteoarthritis waiting for arthroplasty

Background: Cross cultural validity is of vital importance for international comparisons. Objective: To investigate the validity of international Dutch-English comparisons when using the Dutch translation of the Western Ontario and McMaster Universities osteoarthritis index (WOMAC). Patients and Methods: The dimensionality, reliability, construct validity, and cross cultural equivalence of the Dutch WOMAC in Dutch and Canadian patients waiting for primary total hip arthroplasty was investigated. Unidimensionality and cross cultural equivalence was quantified by principal component and Rasch analysis. Intratest reliability was quantified with Cronbach's α, and test-retest reliability with the intraclass correlation coefficient. Construct validity was quantified by correlating sum scores of the Dutch WOMAC, Arthritis Impact Measurement Scales (Dutch AIMS2), Health Assessment Questionnaire (Dutch HAQ), and Harris Hip Score (Dutch HHS). Results: The WOMAC was completed by 180 Dutch and 244 English speaking Canadian patients. Unidimensionality of the Dutch WOMAC was confirmed by principal component and Rasch analysis (good fit for 20/22 items). The intratest reliability of the Dutch WOMAC for pain and physical functioning was 0.88 and 0.96, whereas the test-retest reliability was 0.77 and 0.92, respectively. Dutch WOMAC pain sum score correlated 0.69 with Dutch HAQ pain, and 0.39 with Dutch HHS pain. Dutch WOMAC physical functioning sum score correlated 0.46 with Dutch AIMS2 mobility, 0.62 with Dutch AIMS2 walking and bending, 0.67 with Dutch HAQ disability, and 0.49 with Dutch HHS function. Differential item functioning (DIF) was shown for 6/22 Dutch items. Conclusions: The Dutch WOMAC permits valid international Dutch-English comparisons after correction for DIF

Estimating mangrove tree biomass and carbon content: A comparison of forest inventory techniques and drone imagery

Published: 22 January 2020Mangroves provide many ecosystem services including a considerable capacity to sequester and store large amounts of carbon, both in the sediment and in the above-ground biomass. Assessment of mangrove above-ground carbon stock relies on accurate measurement of tree biomass, which traditionally involves collecting direct measurements from trees and relating these to biomass using allometric relationships. We investigated the potential to predict tree biomass using measurements derived from unmanned aerial vehicle (UAV), or drone, imagery. This approach has the potential to dramatically reduce time-consuming fieldwork, providing greater spatial survey coverage and return for effort, and may enable data to be collected in otherwise hazardous or inaccessible areas. We imaged an Avicennia marina (grey mangrove) stand using an RGB camera mounted on a UAV. The imaged trees were subsequently felled, enabling physical measurements to be taken for traditional biomass estimation techniques, as well as direct measurements of biomass and tissue carbon content. UAV image-based tree height measurements were highly accurate (R2 = 0.98). However, the variables that could be measured from the UAV imagery (tree height and canopy area) were poor predictors of tree biomass. Using the physical measurement data, we identified that trunk diameter is a key predictor of A. marina biomass. Unfortunately, trunk diameter cannot be directly measured from the UAV imagery, but it can be predicted (with some error) using models that incorporate other UAV image-based measurements, such as tree height and canopy area. However, reliance on second-order estimates of trunk diameter leads to increased uncertainty in the subsequent predictions of A. marina biomass, compared to using physical measurements of trunk diameter taken directly from the trees. Our study demonstrates that there is potential to use UAV-based imagery to measure mangrove A. marina tree structural characteristics and biomass. Further refinement of the relationship between UAV image-based measurements and tree diameter is needed to reduce error in biomass predictions. UAV image-based estimates can be made far more quickly and over extensive areas when compared to traditional data collection techniques and, with improved accuracy through further model-calibration, have the potential to be a powerful tool for mangrove biomass and carbon storage estimation.Alice R. Jones, Ramesh Raja Segaran, Kenneth D. Clarke, Michelle Waycott, William S. H. Goh and Bronwyn M. Gillander

Incidence of schizophrenia and other psychoses in ethnic minority groups: results from the MRC AESOP Study

Background. The incidence of schizophrenia in the African-Caribbean population in England is reported to be raised. We sought to clarify whether (a) the rates of other psychotic disorders are increased, (b) whether psychosis is increased in other ethnic minority groups, and (c) whether particular age or gender groups are especially at risk. Method. We identified all people (n=568) aged 16-64 years presenting to secondary services with their first psychotic symptoms in three well-defined English areas (over a 2-year period in Southeast London and Nottingham and a 9-month period in Bristol). Standardized incidence rates and incidence rate ratios (IRR) for all major psychosis syndromes for all main ethnic groups were calculated. Results. We found remarkably high IRRs for both schizophrenia and manic psychosis in both African-Caribbeans (schizophrenia 9.1, manic psychosis 8.0) and Black Africans (schizophrenia 5.8, manic psychosis 6.2) in men and women. IRRs in other ethnic minority groups were modestly increased as were rates for depressive psychosis and other psychoses in all minority groups. These raised rates were evident in all age groups in our study. Conclusions. Ethnic minority groups are at increased risk for all psychotic illnesses but African- Caribbeans and Black Africans appear to be at especially high risk for both schizophrenia and mania. These findings suggest that (a) either additional risk factors are operating in African- Caribbeans and Black Africans or that these factors are particularly prevalent in these groups, and that (b) such factors increase risk for schizophrenia and mania in these groups