309 research outputs found

    Self-recruiting species in farmer managed aquatic systems: their importance to the livelihoods of the rural poor in Southeast Asia

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    The self-recruiting species (SRS) are aquatic animals that can be harvested regularly from a farmer managed system without regular stocking as described by Little (2002a, b). The potential and current role of self-recruiting species from farmer managed aquatic systems (FMAS) is often overlooked, whilst much attention has been given to stocked species (often associated in conventional culture ponds and cages) as well as the fisheries sector (often relates to large water bodies i.e. river lakes and reservoirs). Using the combination of qualitative and quantitative research approaches, the current status, the important contribution of SRS and factors undermining this contribution to the livelihoods of rural households in mainland Southeast (SE) Asia were investigated. The overall analysis of this research was done based from the sustainable livelihood (SL) framework (Scoones, 1998; DFID, 1999) in order to have a broader understanding of the importance of SRS as well as the rural livelihoods in selected areas of mainland SE Asia which often benefit from this resource. The research was carried out in rural villages of southeast Cambodia (SEC), northeast Thailand (NET) and Red River Delta in northern Vietnam (RRD). The sites (region of the country) were selected based from the intensity of aquaculture practices (less established and mainly relying on natural production, aquaculture established but also relying on natural production and mainly aquaculture dependent) as well as the agriculture i.e. intensiveness of rice production. Eighteen villages (6 villages/ country) were selected to represent the two agro-ecological zones (i.e. LOW and DRY areas) of the study sites. In order to fully assess the situation and meet the objectives of the research, the study was carried out using three stages which dealt with different approaches and sets of participants/respondents; i) participatory community appraisal (PCA), ii) baseline survey and iii) longitudinal study. The different stages of the research were carried out during the period of April 2001 until September 2004. During the first stage, a series of community appraisals using participatory methods were conducted in all of the participating villages in the three study sites. The participatory appraisal was conducted in order to understand the general rural context in the villages as well as the importance of aquatic resources. Moreover, the PCA in a way helped build rapport between the researcher and the communities. The series of appraisals were conducted with different wellbeing and gender groups (better-off men, better-off women, poor men and poor women). The various shocks, trends and seasonality that influenced the status of living in the community, diversified livelihoods and the differences in preference of socioeconomic and gender groups were analysed in this stage. The important aquatic animals (AA) and the local criteria for determing their importance were the highlights of this stage of the research. The important AA identified were composed of large fish (Channa spp., Clarias spp., Hemibagrus sp, Common, Indian, Silver and Grass carps), small fish (Anabas testudineus, Rasbora spp., Mystus spp., Carassius auratus) as well as non-fish (Macrobrachium spp., Rana spp., Somanniathelpusa sp., Sinotaia spp.) which were particularly important to poorer groups in the community. The local criteria used were mainly food and nutrition related (good taste, easy to cook, versatility in preparation), abundance (availability, ease of catching) as well as economic value (good price). Significant differences were found between various interactions of sites, agro-ecological zones, gender and wellbeing groups. The second stage of the research was the baseline survey (cross-sectional survey) which was also carried out in the same communities and collected information from a total of 540 respondents (30 respondents per village or 180 per country). This stage of the study was carried out in order to generate household level information (mostly quantitative) regarding the socio-economic indicators to triangulate the information generated during the participatory appraisal and the different aquatic systems that existed in the community as well as the various management practices used (not limited to stocking hatchery seed and feeding). The different livelihood resources (human, physical, financial, natural and social capital) and the diversified strategies of rural households in SE Asia were analysed in this phase. Another highlight of this phase was the understanding of the various aquatic systems that rural farmers managed and how they related to the existence of self-recruiting species. The common aquatic resources identified during this phase included farmer managed aquatic systems (FMAS) and openwater bodies (OWB) where rural households usually obtained their aquatic products. The various types of FMAS which included ricefields, trap ponds, household ponds, culture ponds and ditches were identified as important aquatic resources which mainly provide food as well as additional income to the rural poor. All of these FMAS were being managed at various levels which directly affected the SRS population. Different types of farmers were identified based on their attitudes towards and management of SRS: i) SRS positive, farmers who allow and attract SRS into the system, ii) SRS negative, farmers who prevent or eliminate SRS and iii) SRS neutral, farmers doing nothing that would encourage or prevent SRS from entering into the system. Variations were related to the main factors (i.e sites, agroecological zones, wellbeing groups) and their interactions. The final stage of this study was the year-long household survey (longitudinal study) that investigated the seasonality of various aspects of rural livelihoods, status of the different aquatic systems and the important contribution of AA in general, and SRS in particular, to the overall livelihood strategies employed by rural farmers. This phase involved a total of 162 households (9 per village or 54 per country) selected based on the aquatic systems they managed and had access to. Other socio-economic factors (gender and wellbeing) were also considered during the selection of participants in this phase of the study. The results of the year long household survey highlighted the important contributions of SRS: i) to the total AA collections which were utilised in various ways, ii) contribution to overall food consumption in general and AA consumption in particular (which was found to be the most important contribution of SRS), iii) contribution to household nutrition (as a major source of animal protein and essential micro nutrients in rural areas), iv) contribution to income and expenditures, and v) improving the social capital of rural households (through sharing of production and mobilizing community in local resources user group management). Moreover, the social context and the dynamics of inter and intra household relationships were understood, especially the gender issues on division of labour (where women and children played an important part on the production), access and benefits (how women and children were being marginalised in terms of making decision and controlling benefits). The various results of the combined approaches that were utilised in all stages of the research were analysed and presented in this thesis. The results of the community appraisals and the baseline survey were used in setting the context (background) of each topic (e.g. livelihood activities, AA importance, etc). Meanwhile, the results of the longitudinal survey were used in illustrating the trends and highlighted the seasonality of particular issues. Overall the study contributed to knowledge by elucidating the status and roles of self-recruiting species in maintaining/ improving the overall livelihoods of rural farmers in Southeast Asia. Various factors influenced the importance of SRS to rural livelihoods such as social (wellbeing and gender), ecological factors (agroecological zones, intensity of both agriculture and aquaculture) and seasonality. Moreover, results of this thesis illustrated the variations or complexities of aquatic resources in the rural areas and also how and where the SRS fits in the aquaculture – fisheries continuum which therefore can be used in future research and development

    Higgs effective Hlilj vertex from heavy νR and applications to LFV

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    The European Physical Society Conference on High Energy Physics 5-12 July, 2017 VeniceWe present a new computation of the Lepton Flavor Violating effective vertex involving the Higgs boson and two leptons with different flavors. This vertex is generated from the integration to oneloop level of the heavy right handed neutrinos which are considered here within the context of the Low Scale Seesaw Models and with masses close to the TeV scale. We apply the Mass Insertion Approximation technique to compute the loop contributions from these heavy νR and derive a symple analytical formula for the Hli lj effective vertex in terms of the input Yν Yukawa coupling matrix and right handed MR neutrino masses. Some interesting phenomenological applications of this Hli lj effective vertex are also includedWe thank our respective projects: FPA2016-78645-P (MINECO(Spain)/FEDER(EU)); ITN-ELUSIVES H2020-MSCA-ITN-2015//674896 (EU); ANPCyT PICT 2013-2266 (Argentina

    Analysis of the h, H, A → τμ decays induced from SUSY loops within the Mass Insertion Approximation

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    In this paper we study the lepton favor violating decay channels of the neutral Higgs bosons of the Minimal Supersymmetric Standard Model into a lepton and an anti-lepton of different flavor. We work in the context of the most general flavor mixing scenario in the slepton sector, in contrast to the minimal flavor violation assumption more frequently used. Our analytic computation is a one-loop diagrammatic one, but in contrast to the full one-loop computation which is usually referred to the physical slepton mass basis, we use here instead the Mass Insertion Approximation (MIA) which uses the electroweak interaction slepton basis and treats perturbatively the mass insertions changing slepton flavor. By performing an expansion in powers of the external momenta in the relevant form factors, we will be able to separate explicitly in the analytic results the leading non-decoupling (constant at asymptotically large sparticle masses) and the next to leading decoupling contributions (decreasing with the sparticle masses). Our final aim is to provide a set of simple analytic formulas for the form factors and the associated effective vertices, that we think may be very useful for future phenomenological studies of the lepton flavor violating Higgs boson decays, and for their comparison with data. The accuracy of the numerical results obtained with the MIA are also analyzed and discussed here in comparison with the full one-loop results. Our most optimistic numerical estimates for the three neutral Higgs boson decays channels into τ and μ leptons, searching for their maximum rates that are allowed by present constraints from τ → μγ data and beyond Standard Model Higgs boson searches at the LHC, are also included.Facultad de Ciencias ExactasInstituto de Física La Plat

    Search strategies for pair production of heavy Higgs bosons decaying invisibly at the LHC

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    The search for heavy Higgs bosons at the LHC represents an intense experimental program, carried out by the ATLAS and CMS collaborations, which includes the hunt for invisible Higgs decays and dark matter candidates. No significant deviations from the SM backgrounds have been observed in any of these searches, imposing significant constraints on the parameter space of different new physics models with an extended Higgs sector. Here we discuss an alternative search strategy for heavy Higgs bosons decaying invisibly at the LHC, focusing on the pair production of a heavy scalar H together with a pseudoscalar A, through the production mode qq¯→Z*→HA. We identify as the most promising signal the final state made up of 4b+EmissT, coming from the heavy scalar decay mode H→hh→bb¯bb¯ with h being the discovered SM-like Higgs boson with mh=125GeV, together with the invisible channel of the pseudoscalar. We work within the context of simplified MSSM scenarios that contain quite heavy sfermions of most types with O(10)TeV masses, while the stops are heavy enough to reproduce the 125 GeV mass for the lightest SM-like Higgs boson. By contrast, the gauginos/higgsinos and the heavy MSSM Higgs bosons have masses near the EW scale. Our search strategies, for a LHC center-of-mass energy of √s=14TeV, allow us to obtain statistical significances of the signal over the SM backgrounds with values up to ∼1.6σ and ∼3σ for total integrated luminosities of 300fb−1 and 1000fb−1, respectively.Facultad de Ciencias ExactasInstituto de Física La Plat

    In-cell discontinuous reconstruction path-conservative methods for non conservative hyperbolic systems - Second-order extension

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    We are interested in the numerical approximation of discontinuous solutions in non conservative hyperbolic systems. An extension to second-order of a new strategy based on in-cell discontinuous reconstructions to deal with this challenging topic is presented. This extension is based on the combination of the first-order in-cell reconstruction with the standard MUSCL-Hancock reconstruction. The first-order strategy allowed in particular to capture exactly the isolated shocks and this new second-order extension keep this property. Moreover, the well-balanced property of the method is also studied. Several numerical tests are proposed to validate the methods for the Coupled-Burgers system, Gas dynamics equations in Lagrangian coordinates and the modified shallow water system.The research of CP, MC and EPG was partially supported by the Spanish Government (SG), the European Regional Development Fund (ERDF), the Regional Government of Andalusia (RGA), and the University of Málaga (UMA) through the projects of reference RTI2018-096064-B-C21 (SG-ERDF), UMA18-Federja-161 (RGA-ERDF-UMA), and P18-RT-3163 (RGA-ERDF). EPG was also financed by the Junior Scientific Visibility Program from the Foundation Mathématiques Jacques Hadamard for a stay of three month in the Laboratoire de Mathématiques de Versailles (LMV) with reference ANR-11-LABX-0056-LMH, LabEx LMH. TML was supported by the Spanish Government (SG) through the projects of reference RTI2018-096064-B-C22. The authors thank the anonymous reviewer whose comments helped to improve the paper. Funding for open access charge: Universidad de Málaga / CBU

    Search strategies for pair production of heavy Higgs bosons decaying invisibly at the LHC

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    The search for heavy Higgs bosons at the LHC represents an intense experimental program, carried out by the ATLAS and CMS collaborations, which includes the hunt for invisible Higgs decays and dark matter candidates. No significant deviations from the SM backgrounds have been observed in any of these searches, imposing significant constraints on the parameter space of different new physics models with an extended Higgs sector. Here we discuss an alternative search strategy for heavy Higgs bosons decaying invisibly at the LHC, focusing on the pair production of a heavy scalar H together with a pseudoscalar A, through the production mode qq¯→Z*→HA. We identify as the most promising signal the final state made up of 4b+EmissT, coming from the heavy scalar decay mode H→hh→bb¯bb¯ with h being the discovered SM-like Higgs boson with mh=125GeV, together with the invisible channel of the pseudoscalar. We work within the context of simplified MSSM scenarios that contain quite heavy sfermions of most types with O(10)TeV masses, while the stops are heavy enough to reproduce the 125 GeV mass for the lightest SM-like Higgs boson. By contrast, the gauginos/higgsinos and the heavy MSSM Higgs bosons have masses near the EW scale. Our search strategies, for a LHC center-of-mass energy of √s=14TeV, allow us to obtain statistical significances of the signal over the SM backgrounds with values up to ∼1.6σ and ∼3σ for total integrated luminosities of 300fb−1 and 1000fb−1, respectively.Facultad de Ciencias ExactasInstituto de Física La Plat

    Lethal Concentration of Carbonate OF Ca as a Function of the Osmotic Potential of the Solution in Sunflower (Heliantusannuus L.)

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    In order to know the effect of CaCO3 in solution, sunflower seedlings cv. Victoria, an experiment was completely randomized, where five concentrations of calcium carbonate were evaluated to determine the lethal concentration (LC50), pH and EC of the solution under laboratory conditions in the Universidad Tecnologica de Tehuacan, to simulate of excess Ca++ in the soils or nutrient solution. The results indicate, the LC50 was 62.8 mg CaCO3 L-1, so maximum values for pH, EC and calcium absorption, They were achieved at concentrations of 120 and 160 mg L-1 of CaCO3. This work can be concluded, Sunflower can absorb the high levels of calcium and used as an alternative, for remediation of agricultural soils affected hard water and Ca++ salts

    Analysis of the h, H, A → τμ decays induced from SUSY loops within the Mass Insertion Approximation

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    In this paper we study the lepton favor violating decay channels of the neutral Higgs bosons of the Minimal Supersymmetric Standard Model into a lepton and an anti-lepton of different flavor. We work in the context of the most general flavor mixing scenario in the slepton sector, in contrast to the minimal flavor violation assumption more frequently used. Our analytic computation is a one-loop diagrammatic one, but in contrast to the full one-loop computation which is usually referred to the physical slepton mass basis, we use here instead the Mass Insertion Approximation (MIA) which uses the electroweak interaction slepton basis and treats perturbatively the mass insertions changing slepton flavor. By performing an expansion in powers of the external momenta in the relevant form factors, we will be able to separate explicitly in the analytic results the leading non-decoupling (constant at asymptotically large sparticle masses) and the next to leading decoupling contributions (decreasing with the sparticle masses). Our final aim is to provide a set of simple analytic formulas for the form factors and the associated effective vertices, that we think may be very useful for future phenomenological studies of the lepton flavor violating Higgs boson decays, and for their comparison with data. The accuracy of the numerical results obtained with the MIA are also analyzed and discussed here in comparison with the full one-loop results. Our most optimistic numerical estimates for the three neutral Higgs boson decays channels into τ and μ leptons, searching for their maximum rates that are allowed by present constraints from τ → μγ data and beyond Standard Model Higgs boson searches at the LHC, are also included.Facultad de Ciencias ExactasInstituto de Física La Plat

    TLR4 Participates in the Inflammatory Response Induced by the AAF/II Fimbriae From Enteroaggregative Escherichia coli on Intestinal Epithelial Cells

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    Enteroaggregative Escherichia coli (EAEC) infections are one of the most frequent causes of persistent diarrhea in children, immunocompromised patients and travelers worldwide. The most prominent colonization factors of EAEC are aggregative adherence fimbriae (AAF). EAEC prototypical strain 042 harbors the AAF/II fimbriae variant, which mediates adhesion to intestinal epithelial cells and participates in the induction of an inflammatory response against this pathogen. However, the mechanism and the cell receptors implicated in eliciting this response have not been fully characterized. Since previous reports have shown that TLR4 recognize fimbriae from different pathogens, we evaluated the role of this receptor in the response elicited against EAEC by intestinal cells. Using a mutual antagonist against TLR2 and TLR4 (OxPAPC), we observed that blocking of these receptors significantly reduces the secretion of the inflammatory marker IL-8 in response to EAEC and AAF/II fimbrial extract in HT-29 cells. Using a TLR4-specific antagonist (TAK-242), we observed that the secretion of this cytokine was significantly reduced in HT-29 cells infected with EAEC or incubated with AAF/II fimbrial extract. We evaluated the participation of AAF/II fimbriae in the TLR4-mediated secretion of 38 cytokines, chemokines, and growth factors involved in inflammation. A reduction in the secretion of IL-8, GRO, and IL-4 was observed. Our results suggest that TLR4 participates in the secretion of several inflammation biomarkers in response to AAF/II fimbriae
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