2,201 research outputs found

    SUPPLY ANALYSIS FOR CORN IN THE UNITED STATES: THE IMPACT OF CHANGING GOVERNMENT PROGRAMS

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    This paper has two objectives: to analyze acreage supply relationships for corn, the major U.S. feed grain, during the 1948-70 period and to develop and test a general theoretical model for evaluating farm commodity program effectiveness. Hence, special emphasis is devoted to empirical measurement and analysis of the effects of government feed grain policy and programs as they have evolved since 1948. Particular attention is focused on the voluntary feed grain programs of the 1960's.Agricultural and Food Policy, Crop Production/Industries,

    THE GREEN REVOLUTION: ITS IMPACT ON TRADE AND AGRICULTURAL POLICY IN DEVELOPED NATIONS

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    Agricultural and Food Policy, International Relations/Trade,

    A STUDY OF U.S. EXPORTS OF SOYBEANS AND SOYBEAN MEAL

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    International Relations/Trade,

    Mycobacterium tuberculosis infection induces non-apoptotic cell death of human dendritic cells

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    <p>Abstract</p> <p>Background</p> <p>Dendritic cells (DCs) connect innate and adaptive immunity, and are necessary for an efficient CD4<sup>+ </sup>and CD8<sup>+ </sup>T cell response after infection with <it>Mycobacterium tuberculosis </it>(Mtb). We previously described the macrophage cell death response to Mtb infection. To investigate the effect of Mtb infection on human DC viability, we infected these phagocytes with different strains of Mtb and assessed viability, as well as DNA fragmentation and caspase activity. In parallel studies, we assessed the impact of infection on DC maturation, cytokine production and bacillary survival.</p> <p>Results</p> <p>Infection of DCs with live Mtb (H37Ra or H37Rv) led to cell death. This cell death proceeded in a caspase-independent manner, and without nuclear fragmentation. In fact, substrate assays demonstrated that Mtb H37Ra-induced cell death progressed without the activation of the executioner caspases, 3/7. Although the death pathway was triggered after infection, the DCs successfully underwent maturation and produced a host-protective cytokine profile. Finally, dying infected DCs were permissive for Mtb H37Ra growth.</p> <p>Conclusions</p> <p>Human DCs undergo cell death after infection with live Mtb, in a manner that does not involve executioner caspases, and results in no mycobactericidal effect. Nonetheless, the DC maturation and cytokine profile observed suggests that the infected cells can still contribute to TB immunity.</p

    Bladder incarceration following anterior external fixation of a traumatic pubic symphysis diastasis treated with immediate open reduction and internal fixation

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    Anterior pelvic ring disruptions are often associated with injuries to the genitourinary structures with the potential for considerable resultant morbidity. Herniation of the bladder into the symphyseal region after injury with subsequent entrapment upon reduction of the symphyseal diastasis has seldom been reported in the literature. We report such a case involving bladder herniation and subsequent entrapment after attempted closed reduction with anterior pelvic external fixation immediately treated with open reduction and internal fixation along with a review of the literature

    Understanding the selective etching of electrodeposited ZnO nanorods

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    ZnO nanotubes were prepared by selective dissolution of electrodeposited nanorods. The effect of solution pH, rod morphology, and chloride ion concentration on the dissolution mechanism was studied. The selective etching was rationalized in terms of the surface energy of the different ZnO crystal faces and reactant diffusion. The nanorod diameter and chloride concentration are the most influential parameters on the dissolution mechanism because they control homogeneous dissolution or selective etching of the (110) and (002) surfaces. Bulk solution pH only has an effect on the rate of dissolution. By accurate control of the dissolution process, the nanomorphology can be tailored, and the formation of rods with a thin diameter (10-20 nm), cavity, or ultra-thin-walled tubes (2-5 nm) can be achieved

    Micromechanisms of compressive failure of fibre reinforced polymers

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    Fibre reinforced polymers benefit from high flexural strength, corrosion resistance and low density. These qualities make them a candidate to substitute the conventional rigid steel pipelines for subsea transport of oil and gas. However, deep water pipelines are subject to high external hydrostatic compressive stresses alongside variable internal fluid pressure that can result in high compressive hoop, radial and axial stress. For aligned fibre reinforced composites, compressive strength is generally lower than the tensile strength and a design limiting factor. Therefore, failure mechanisms and conditions need to be well understood in order to design safe and cost-effective structures. Please click Additional Files below to see the full abstract

    Reactive oxygen species induce virus-independent MAVS-oligomerization in systemic lupus erythematosus

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    The increased expression of genes induced by type I interferon (IFN) is characteristic of viral infections and systemic lupus erythematosus (SLE). We showed that mitochondrial antiviral signaling (MAVS) protein, which normally forms a complex with retinoic acid gene I (RIG-I)–like helicases during viral infection, was activated by oxidative stress independently of RIG-I helicases. We found that chemically generated oxidative stress stimulated the formation of MAVS oligomers, which led to mitochondrial hyperpolarization and decreased adenosine triphosphate production and spare respiratory capacity, responses that were not observed in similarly treated cells lacking MAVS. Peripheral blood lymphocytes of SLE patients also showed spontaneous MAVS oligomerization that correlated with the increased secretion of type I IFN and mitochondrial oxidative stress. Furthermore, inhibition of mitochondrial reactive oxygen species (ROS) by the mitochondria-targeted antioxidant MitoQ prevented MAVS oligomerization and type I IFN production. ROS-dependent MAVS oligomerization and type I IFN production were reduced in cells expressing the MAVS-C79F variant, which occurs in 30% of sub-Saharan Africans and is linked with reduced type I IFN secretion and milder disease in SLE patients. Patients expressing the MAVS-C79F variant also had reduced amounts of oligomerized MAVS in their plasma compared to healthy controls. Together, our findings suggest that oxidative stress–induced MAVS oligomerization in SLE patients may contribute to the type I IFN signature that is characteristic of this syndrome

    Determining the Fundamental Failure Modes in Ni-rich Lithium Ion Battery Cathodes

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    Challenges associated with in-service mechanical degradation of Li-ion battery cathodes has prompted a transition from polycrystalline to single crystal cathode materials. Whilst for single crystal materials, dislocation-assisted crack formation is assumed to be the dominating failure mechanism throughout battery life, there is little direct information about their mechanical behaviour, and mechanistic understanding remains elusive. Here, we demonstrated, using in situ micromechanical testing, direct measurement of local mechanical properties within LiNi0.8Mn0.1Co0.1O2 single crystalline domains. We elucidated the dislocation slip systems, their critical stresses, and how slip facilitate cracking. We then compared single crystal and polycrystal deformation behaviour. Our findings answer two fundamental questions critical to understanding cathode degradation: What dislocation slip systems operate in Ni-rich cathode materials? And how does slip cause fracture? This knowledge unlocks our ability to develop tools for lifetime prediction and failure risk assessment, as well as in designing novel cathode materials with increased toughness in-service

    Sorption behaviour of per- and polyfluoroalkyl substances (PFASs) in tropical soils

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    The sorption behaviour of three perfluoroalkyl substances (PFASs), namely perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS), was determined on 28 tropical soils. Tropical soils are often highly weathered, richer in sesquioxides than temperate soils and may contain variable charge minerals. There are little data on sorption of PFASs in tropical soils. The highest Kd values were found for PFOS with mean values ranging from 0 to 31.6 L/kg. The Kd values for PFOA and PFHxS ranged from 0 to 4.9 L/kg and from 0 to 5.6 L/kg, respectively. While these values are in the range of literature sorption data, the average Kd values for PFOS and PFOA from the literature were 3.7 times and 3.6 times higher, respectively, than those measured in this study. Stepwise regression analysis did explain some of the variance, but with different explanatory variables for the different PFASs. The main soil properties explaining sorption for PFOS and PFOA were oxalate-extractable Al and pH, and for PFHxS was pH
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