5,940 research outputs found

    LM radar reflectivity simulation Final report

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    Ultrasonic simulation of lunar module radar reflectivit

    Storm‐time configuration of the inner magnetosphere: Lyon‐Fedder‐Mobarry MHD code, Tsyganenko model, and GOES observations

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    [1] We compare global magnetohydrodynamic (MHD) simulation results with an empirical model and observations to understand the magnetic field configuration and plasma distribution in the inner magnetosphere, especially during geomagnetic storms. The physics-based Lyon-Fedder-Mobarry (LFM) code simulates Earth\u27s magnetospheric topology and dynamics by solving the equations of ideal MHD. Quantitative comparisons of simulated events with observations reveal strengths and possible limitations and suggest ways to improve the LFM code. Here we present a case study that compares the LFM code to both a semiempirical magnetic field model and to geosynchronous measurements from GOES satellites. During a magnetic cloud event, the simulation and model predictions compare well qualitatively with observations, except during storm main phase. Quantitative statistical studies of the MHD simulation shows that MHD field lines are consistently under-stretched, especially during storm time (Dst \u3c −20 nT) on the nightside, a likely consequence of an insufficient representation of the inner magnetosphere current systems in ideal MHD. We discuss two approaches for improving the LFM result: increasing the simulation spatial resolution and coupling LFM with a ring current model based on drift physics (i.e., the Rice Convection Model (RCM)). We show that a higher spatial resolution LFM code better predicts geosynchronous magnetic fields (not only the average Bz component but also higher-frequency fluctuations driven by the solar wind). An early version of the LFM/RCM coupled code, which runs so far only for idealized events, yields a much-improved ring current, quantifiable by decreased field strengths at all local times compared to the LFM-only code

    A high flux source of cold strontium atoms

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    We describe an experimental apparatus capable of achieving a high loading rate of strontium atoms in a magneto-optical trap operating in a high vacuum environment. A key innovation of this setup is a two dimensional magneto-optical trap deflector located after a Zeeman slower. We find a loading rate of 6x10^9/s whereas the lifetime of the magnetically trapped atoms in the 3P2 state is 54s.Comment: 12 pages, 16 figure

    Socio-economic Determinants of Cassava Production in Benue State, Nigeria.

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    The study examined the determinants of cassava production in Benue State Nigeria. A total of 180 farmers were selected across the state using multi-stage sampling technique. Data, which comprised information on the socio-economic characteristics and other quantitative variables relevant to the study, were collected using a well structured questionnaire and personal interviews. The social- economic characteristics were analyzed using descriptive statistics such as percentages and frequencies; simple multiple regression technique was used to analyze the production functions of cassava farmers. The results obtained revealed that R2 value was 0.419 indicating that 41.9% of variation in cassava production was accounted for by the variables considered in the study. Specifically, age of the farmers, occupation, household size, farming experience, level of education of farmers, farms size and fertilizer input where all significant and are important variables that affected the production of cassava in the study area. Given the enormous potential of cassava production in the study area, it has become so imperative that youths be encourage to participate effectively in cassava production, seeing that majority of the farmers are aged and will retire from active farming. This is to ensure food security. Effective structure should be put in place for the input and credit facilities provided by the government, this will ensure that these facilities get to those who need it and will in turn help the farmers expand their production. This study, although base in Benue State, may have implications for other States with similar situation. This will help the state meet self-sufficiency in food production and so be able to feed her teeming population

    Mammographic density and its interaction with other breast cancer risk factors in an Asian population

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    10.1038/sj.bjc.6606085British Journal of Cancer1045871-874BJCA

    ΔFosB Regulates Gene Expression and Cognitive Dysfunction in a Mouse Model of Alzheimer\u27s Disease.

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    Alzheimer\u27s disease (AD) is characterized by cognitive decline and 5- to 10-fold increased seizure incidence. How seizures contribute to cognitive decline in AD or other disorders is unclear. We show that spontaneous seizures increase expression of ΔFosB, a highly stable Fos-family transcription factor, in the hippocampus of an AD mouse model. ΔFosB suppressed expression of the immediate early gene c-Fos, which is critical for plasticity and cognition, by binding its promoter and triggering histone deacetylation. Acute histone deacetylase (HDAC) inhibition or inhibition of ΔFosB activity restored c-Fos induction and improved cognition in AD mice. Administration of seizure-inducing agents to nontransgenic mice also resulted in ΔFosB-mediated suppression of c-Fos, suggesting that this mechanism is not confined to AD mice. These results explain observations that c-Fos expression increases after acute neuronal activity but decreases with chronic activity. Moreover, these results indicate a general mechanism by which seizures contribute to persistent cognitive deficits, even during seizure-free periods

    Potencial produtivo de dois cultivares de tomate, plantados em sucessão ao milho, visando diminuir a incidência de Murcha Bacteriana.

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    Com a finalidade de indicação de inovações tecnológicas que possibilitem a produção desta hortaliça em grande escala, este trabalho objetiva avaliar o potencial produtivo e comercial de dois cultivares de tomate e técnicas de manejo visando diminuir a incidência de murcha bacteriana, em sistema de cultivo protegido, na região de Iranduba ? AM

    Efeito da rotação de culturas sobre os índices produtivos de dois cultivares de tomate no município de Iranduba-AM.

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    O projeto visa avaliar o efeito da rotação de culturas sobre os índices produtivos de dois cultivares de tomate na redução da incidência de murcha bacteriana, na região de Iranduba - Amazonas

    Microwave synthesis of magnetically separable ZnFe2O4-reduced graphene oxide for wastewater treatment

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    A magnetically separable ZnFe2O4-reduced graphene oxide (rGO) nano-composite was synthesised via a microwave method. Field emission scanning electron microscopy images of the nano-composite showed a uniform dispersion of nanoparticles on the rGO sheets. The performance of the nano-composite in wastewater treatment was assessed by observing the decomposition of methylene blue. The nano-composite showed excellent bifunctionality, i.e. adsorption and photocatalytic degradation of methylene blue, for up to five cycles of water treatment when illuminated with light from a halogen bulb. In contrast, water treatment with the nano-composite without illumination and the illuminated rGO, with no decoration of nanoparticles, diminished significantly after the first treatment. The reclamation of the ZnFe2O4-rGO nano-composite from treated water could be easily achieved by applying an external magnetic field
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