839 research outputs found

    Biological Control Efforts of Water hyacinth (Eichhornia crassipes (Mart.) Solm) on Kainji Lake, Nigeria

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    Biological control of water hyacinth (Eichhornia crassipes (Mart.) Solm) was monitored on Kainji Lake between 1995 and 1999. The two most important host specific natural enemies of water hyacinth (Neochetina eichhorniae and N. bruchi) were used and impacts of the weevils on water hyacinth were monitored on tri-monthly basis. The manual control initiated by the National Institute for Freshwater Fisheries Research (NIFFR) encouraged the fishermen to physically remove water hyacinth from their shores and open water. The lake hydrology, most especially during the drawdown period when the water volume is reduced tremendously, allows water hyacinth plants to be stranded by the bank of the lake thereby leading to massive destruction of the weed population and consequently the weevils population stability. The floristic composition of macrophyte intimately mixed with the water hyacinth was also monitored during the low and high water regimes. Among the prominent plant species found with water hyacinth included Echinochloa stagnina, Mimosa pigra, Polygonium senegalensis Polygonium lanigarium. Sesbania dalzelli, and Vosia cuspidata were found competing with the much favoured Echinochloa spp which serves as forage to livestock around the lake; However, no incidence of weevil attack was observed on any of the vegetation mixed with water hyacinth. Keywords: Biocontol, Kainji Lake, Water hyacinth, Weevils

    The Borexino Thermal Monitoring & Management System and simulations of the fluid-dynamics of the Borexino detector under asymmetrical, changing boundary conditions

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    A comprehensive monitoring system for the thermal environment inside the Borexino neutrino detector was developed and installed in order to reduce uncertainties in determining temperatures throughout the detector. A complementary thermal management system limits undesirable thermal couplings between the environment and Borexino's active sections. This strategy is bringing improved radioactive background conditions to the region of interest for the physics signal thanks to reduced fluid mixing induced in the liquid scintillator. Although fluid-dynamical equilibrium has not yet been fully reached, and thermal fine-tuning is possible, the system has proven extremely effective at stabilizing the detector's thermal conditions while offering precise insights into its mechanisms of internal thermal transport. Furthermore, a Computational Fluid-Dynamics analysis has been performed, based on the empirical measurements provided by the thermal monitoring system, and providing information into present and future thermal trends. A two-dimensional modeling approach was implemented in order to achieve a proper understanding of the thermal and fluid-dynamics in Borexino. It was optimized for different regions and periods of interest, focusing on the most critical effects that were identified as influencing background concentrations. Literature experimental case studies were reproduced to benchmark the method and settings, and a Borexino-specific benchmark was implemented in order to validate the modeling approach for thermal transport. Finally, fully-convective models were applied to understand general and specific fluid motions impacting the detector's Active Volume.Comment: arXiv admin note: substantial text overlap with arXiv:1705.09078, arXiv:1705.0965

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    The significance of cheese sampling in the determination of histamine concentration: Distribution pattern of histamine in ripened cheeses

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    Cheeses are becoming a major safety and public health concern: cheeses available in supermarkets occasionally contain high histamine concentrations that can have negative effects on consumer health. In this study, we have attempted to assess the histamine distribution pattern in ripened cheeses, with the purpose of establishing a correct cheese sampling strategy for the quantification of histamine. To this aim, histamine was determined in four distinct areas of twelve long-ripened hard cheeses: the external and internal rind, along with the outer and inner core of the wedge. The concentrations measured were remarkably different: histamine accumulated in the central core, whereas the lowest amount was found in the peripheral rind. To explain this heterogenous distribution, histamine producers were determined in the four areas by identifying the hdc sequences obtained from cheese samples. Non-starter bacteria were identified as main histamine producers; however, these microbiota were homogeneously distributed throughout the wedge. Nevertheless, the analysis of psychochemical properties of the different areas revealed an observable trend: histamine tended to accumulate in the saltier, more humid, and less oxidized areas in a wedge. Overall, this study highlights the significance of a correct sampling strategy when histamine is quantified in cheese

    The Nylon Scintillator Containment Vessels for the Borexino Solar Neutrino Experiment

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    Borexino is a solar neutrino experiment designed to observe the 0.86 MeV Be-7 neutrinos emitted in the pp cycle of the sun. Neutrinos will be detected by their elastic scattering on electrons in 100 tons of liquid scintillator. The neutrino event rate in the scintillator is expected to be low (~0.35 events per day per ton), and the signals will be at energies below 1.5 MeV, where background from natural radioactivity is prominent. Scintillation light produced by the recoil electrons is observed by an array of 2240 photomultiplier tubes. Because of the intrinsic radioactive contaminants in these PMTs, the liquid scintillator is shielded from them by a thick barrier of buffer fluid. A spherical vessel made of thin nylon film contains the scintillator, separating it from the surrounding buffer. The buffer region itself is divided into two concentric shells by a second nylon vessel in order to prevent inward diffusion of radon atoms. The radioactive background requirements for Borexino are challenging to meet, especially for the scintillator and these nylon vessels. Besides meeting requirements for low radioactivity, the nylon vessels must also satisfy requirements for mechanical, optical, and chemical properties. The present paper describes the research and development, construction, and installation of the nylon vessels for the Borexino experiment

    Butterflies as bioindicators of metal contamination

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    Anthropogenic trace metal contamination has significantly increased and has caused many hazardous consequences for the ecosystems and human health. The Terni basin valley (Central Italy) shows a heavy load of pollutants from industrial activities, while the characteristic orography structure of the valley favours air stagnation, thus limiting air pollution dispersal. The present study conducted in 2014 aimed to determine the concentration of ten metals in five species of butterflies at nine sites in the Terni valley along a 21-km-long transect, including both relatively pristine and industrial areas. At sites where soil contamination was high for a given metal, such as for chromium as in the case of site 4 (the closest to the steel plant) and for lead as in the case of site 2 (contaminated by a firing range), higher levels of contamination were observed in the tissues of butterflies. We found a correlation between soil contamination and the concentration of Cr, Al and Sr in the tissues of some species of butterflies. The sensitivity to contamination differed among the five species; in particular, Coenonympha pamphilus was generally the species that revealed the highest concentrations of all the ten trace metals at the sites closer to the industrial area. It is known that C. pamphilus is a sedentary species and that its host plants are the Poaceae, capable of accumulating high quantities of metals in their rhizosphere region, thus providing the link with soil contamination. Therefore, monitoring the metal concentration levels in butterflies might be a good indicator and a control tool of environmental quality, specifically in areas affected by high anthropogenic pollution loads linked to a specific source

    Meta Analysis Study Of Progesterone Receptors Effect on Parturition

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    Prematurity is associated with morbidity and mortality. There is alot of causative factors that involved. One of the contributing factors is the presence of uterine contractions that occur prematurely. This is due to a decrease in progesterone levels. This decrease can be achieved by changing the levels of the progesterone receptor (PR) isoform in the myometrium. Objective: To determine whether there is a connection between changes in progesterone receptor isoform levels on labor. This systematic study was arranged according to Prefered Reporting Items For Systematic Review and Meta-Analysis (PRISMA). The articles studied were observational studies. Each article was tested for the quality of the Newcastle-Ottawa Scale literature because the articles used were of the case control type. From the search results using the search strategy in PUBMED, there were 190 articles which were then selected based on title, abstract, and inclusion and exclusion criteria, obtained 4 articles that fit the criteria desired by the researcher. From the results of a systematic study, it was found that the number of progesterone receptor ratios in pregnant women who had spontaneous labor compared to pregnant women who gave birth via planned cesarean section. Pregnancy with in labor experienced an increase in the PR-A/PR-B ratio by 1.12 times compared to that of cesarean section delivery
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