3,792 research outputs found

    Companion modelling for exploring natural resource management strategies in Palawanm, The Philippines

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    This paper reports experiences and lessons of a continuing study on the use of a contemporary analytical tool, Multi-agent Systems (MAS), to study the dynamics and complex interactions among stakeholders in the management of common renewable resources. In the MAS model, a renewable resource management system is represented with different autonomous entities, called agents, that are able to act, interact with other agents, and be affected by objects in the environment. In this study, the MAS model is developed using the Companion Modelling (ComMod) approach, a collaborative development of a MAS model between the stakeholders and researchers which places primary importance on the quality of process to ensure that the tools developed are acceptable and used with confidence. This approach involves the development and application of computer simulations and role-playing games (RPGs) to validate the MAS model as well as learn from it. Inferences are drawn from the learning and negotiation processes that the stakeholders and researchers undergo in the collaborative development of the MAS model and the techniques used to realize this model, i.e. computer simulation and RPG, as well as the development of a unified resource management plan for three villages. For the community, having acknowledged the RPG as a reliable representation of their reality, they see these tools as vehicles to reach the appropriate stakeholders and communicate their concerns about their livelihoods and resources. For local government agencies and non-government organizations, these tools serve as eye-openers about the dire livelihood conditions of the community. Furthermore, local governments see the RPG and computer simulation as effective techniques to inform and educate people about their plans or programs for the management of resources and livelihood for the community. The stakeholders also agree that these tools are useful in coming together and discussing issues pertaining to the management of their natural resources and livelihood activities. Given the benefits that could be derived from ComMod and MAS modelling in NRM, these techniques display a great potential in plantation management for increasing the financial returns

    Flow field and wake structure characteristics imposed by single seagrass blade surrogates

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    Seagrass surrogates are commonly used to mimic the behaviour of seagrasses exposed to currents and their effects on flow fields. The interaction is highly dependent on the chosen mechanic and geometric properties of the surrogates and needs to be understood in order to design artificial meadows. The interaction of single surrogates in unidirectional flow fields is studied by means of physical modelling. Surrogates made of plastic materials with different flexural rigidities, buoyancies and geometries are exposed to varying flow velocities. The instantaneous velocity fields in the vicinity and wake of the surrogates are measured by stereoscopic Particle Image Velocimetry (PIV). All employed surrogates disrupt and interact with the flow field by changing their posture. An empirical relation is derived between the flexural rigidity, buoyancy and characteristic diameter of the surrogates and the imposed differences in the attenuation ratio of flow velocities. Further, the approaching flow velocity and distance behind the surrogate influence the estimated attenuation. The vortex shedding frequency imposed by artificial seagrass is lower than frequencies determined for infinite, rigid cylindrical structures. Three main characterizing properties: the modulus of elasticity, buoyancy and cross-sectional dimensions need to be taken into account for design of artificial seagrass meadows. Our findings advance knowledge of fluid-structure interactions of flexible materials and help to progress proper design of artificial seagrass meadows

    Toroidal magnetized iron neutrino detector for a neutrino factory

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    A neutrino factory has unparalleled physics reach for the discovery and measurement of CP violation in the neutrino sector. A far detector for a neutrino factory must have good charge identification with excellent background rejection and a large mass. An elegant solution is to construct a magnetized iron neutrino detector (MIND) along the lines of MINOS, where iron plates provide a toroidal magnetic field and scintillator planes provide 3D space points. In this paper, the current status of a simulation of a toroidal MIND for a neutrino factory is discussed in light of the recent measurements of large θ13. The response and performance using the 10 GeV neutrino factory configuration are presented. It is shown that this setup has equivalent δCP reach to a MIND with a dipole field and is sensitive to the discovery of CP violation over 85% of the values of δCP

    Implications of Host Genetic Variation on the Risk and Prevalence of Infectious Diseases Transmitted Through the Environment

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    Previous studies have shown that host genetic heterogeneity in the response to infectious challenge can affect the emergence risk and the severity of diseases transmitted through direct contact between individuals. However, there is substantial uncertainty about the degree and direction of influence owing to different definitions of genetic variation, most of which are not in line with the current understanding of the genetic architecture of disease traits. Also, the relevance of previous results for diseases transmitted through environmental sources is unclear. In this article a compartmental genetic–epidemiological model was developed to quantify the impact of host genetic diversity on epidemiological characteristics of diseases transmitted through a contaminated environment. The model was parameterized for footrot in sheep. Genetic variation was defined through continuous distributions with varying shape and degree of dispersion for different disease traits. The model predicts a strong impact of genetic heterogeneity on the disease risk and its progression and severity, as well as on observable host phenotypes, when dispersion in key epidemiological parameters is high. The impact of host variation depends on the disease trait for which variation occurs and on environmental conditions affecting pathogen survival. In particular, compared to homogeneous populations with the same average susceptibility, disease risk and severity are substantially higher in populations containing a large proportion of highly susceptible individuals, and the differences are strongest when environmental contamination is low. The implications of our results for the recording and analysis of disease data and for predicting response to selection are discussed

    Radioisotopes demonstrate the contrasting bioaccumulation capacities of heavy metals in embryonic stages of cephalopod species

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    Cephalopods play a key role in many marine trophic food webs and also constitute alternative fishery resources in the context of the ongoing decline in finfish stocks. Most coastal cephalopod species of commercial importance migrate into shallow waters during the breeding season to lay their eggs, and are consequently subjected to coastal contamination. Eggs of common cuttlefish Sepia officinalis, European squid Loligo vulgaris, common octopus Octopus vulgaris and the sepiolid Rossia macrosoma were exposed during embryonic development to dissolved 110mAg, 109Cd, 60Co, 54Mn and 65Zn in order to determine their metal accumulation efficiencies and distribution among different egg compartments. Cuttlefish eggs, in which hard shells enclose the embryos, showed the lowest concentration factor (CF) values despite a longer duration of exposure. In contrast, octopus eggs, which are only protected by the chorionic membrane, accumulated the most metal. Uptake appears to be linked to the selective retention properties of the egg envelopes with respect to each element. The study also demonstrated that the octopus embryo accumulated 110mAg directly from the dissolved phase and also indirectly through assimilation of the contaminated yolk. These results raise questions regarding the potential contrasting vulnerability of early life stages of cephalopods to the metallic contamination of coastal water

    VALES: IV. Exploring the transition of star formation efficiencies between normal and starburst galaxies using APEX/SEPIA Band-5 and ALMA at low redshift

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    In this work we present new APEX/SEPIA Band-5 observations targeting the CO (J=2-1J=2\text{-}1) emission line of 24 Herschel-detected galaxies at z=0.1−0.2z=0.1-0.2. Combining this sample {with} our recent new Valpara\'iso ALMA Line Emission Survey (VALES), we investigate the star formation efficiencies (SFEs = SFR/MH2M_{\rm H_{2}}) of galaxies at low redshift. We find the SFE of our sample bridges the gap between normal star-forming galaxies and Ultra-Luminous Infrared Galaxies (ULIRGs), which are thought to be triggered by different star formation modes. Considering the SFE′\rm SFE' as the SFR and the LCO′L'_{\rm CO} ratio, our data show a continuous and smooth increment as a function of infrared luminosity (or star formation rate) with a scatter about 0.5 dex, instead of a steep jump with a bimodal behaviour. This result is due to the use of a sample with a much larger range of sSFR/sSFRms_{\rm ms} using LIRGs, with luminosities covering the range between normal and ULIRGs. We conclude that the main parameters controlling the scatter of the SFE in star-forming galaxies are the systematic uncertainty of the αCO\alpha_{\rm CO} conversion factor, the gas fraction and physical size.Comment: 9pages, 7 figures, 1 table, accepted for publication in MNRA

    Microbiologic follow-up study in adult bronchiectasis

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    SummaryThere is minimal published longitudinal data about pathogenic microorganisms in adults with bronchiectasis. Therefore a study was undertaken to assess the microbiologic profile over time in bronchiectasis.A prospective study of clinical and microbiologic outcomes was performed. Subjects were assessed by a respiratory physician and sputum sample were collected for analysis. Subjects were followed up and had repeat assessment performed.Eighty-nine subjects were followed up for a period of 5.7±3.6 years. On initial assessment the two most common pathogens isolated were Haemophilus influenzae (47%) and Pseudomonas aeruginosa (12%) whilst 21% had no pathogens isolated. On follow-up review results were similar (40% H. influenzae, 18% P. aeruginosa and 26% no pathogens). The prevalence of antibiotic resistance of isolates increased from 13% to 30%. Analysis of a series of H. influenzae isolates showed they were nearly all nontypeable and all were different subtypes. Subjects with no pathogens isolated from their sputum had the mildest disease, while subjects with P. aeruginosa had the most severe bronchiectasis.Many subjects with bronchiectasis are colonized with the same bacterium over an average follow-up of 5 years. Different pathogens are associated with different patterns of clinical disease

    Synthesis of direct and maternal genetic compounds of economically important traits from beef breed-cross evaluations

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    Published information on relative performance of beef breed crosses was used to derive combined estimates of purebred breed values for predominant temperate beef breeds. The sources of information were largely from the United States, Canada, and New Zealand, although some European estimates were also included. Emphasis was on maternal traits of potential economic importance to the suckler beef production system, but some postweaning traits were also considered. The estimates were taken from comparison studies undertaken in the 1970s, 1980s and 1990s, each with representative samples of beef breeds used in temperate agriculture. Weighting factors for breed-cross estimates were derived using the number of sires and offspring that contributed to that estimate. These weights were then used in a weighted multiple regression analysis to obtain single purebred breed effects. Both direct additive and maternal additive genetic effects were estimated for preweaning traits. Important genetic differences between the breeds were shown for many of the traits. Significant regression coefficients were estimated for the effect of mature weight on calving ease, both maternal and direct additive genetic, survival to weaning direct, and birth weight direct. The breeds with greater mature weight were found to have greater maternal genetic effects for calving ease but negative direct genetic effects on calving ease. A negative effect of mature weight on the direct genetic effect of survival to weaning was observed. A cluster analysis was done using 17 breeds for which information existed on nine maternal traits. Regression was used to predict breed-cross-specific heterosis using genetic distance. Only five traits, birth weight, survival to weaning, cow fertility, and preweaning and postweaning growth rate had enough breed-cross-specific heterosis estimates to develop a prediction model. The breed biological values estimated provide a basis to predict the biological value of crossbred suckler cows and their offspring
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