277 research outputs found

    Evaluation of perennial cereal rye longevity and forage production when harvested at different stages of maturities and under grazing

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    Non-Peer ReviewedPerennial Cereal Rye (PC rye) (Secale cereale) has been promoted as a highly productive perennial forage crop for hay/silage and grazing for dryland areas. However earlier research done at Agriculture and Agri-Food Canada – Semiarid Prairie Agricultural Research Centre (AAFC-SPARC) have found that time of seeding and defoliation on PC rye can greatly affect the number of plants surviving through the winter. Current research at AAFC-SPARC indicated that the stage of harvest (preboot, boot and flowering) does affect stand survival and that PC rye longevity is lower (P<0.001) than other short lived forage species, such as, Dahurian wildrye and Slender wheatgrass under irrigation or dryland. Grazing studies at AAFC-SPARC also observed PC rye plant counts decline by over 48% after two years of moderate grazing at the boot to heading plant stage

    Analysis of Control Strategies for Aircraft Flight Upset Recovery

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    This paper proposes a framework for studying the ability of a control strategy, consisting of a control law and a command law, to recover an aircraft from ight conditions that may extend beyond the normal ight envelope. This study was carried out (i) by evaluating time responses of particular ight upsets, (ii) by evaluating local stability over an equilibrium manifold that included stall, and (iii) by bounding the set in the state space from where the vehicle can be safely own to wings-level ight. These states comprise what will be called the safely recoverable ight envelope (SRFE), which is a set containing the aircraft states from where a control strategy can safely stabilize the aircraft. By safe recovery it is implied that the tran- sient response stays between prescribed limits before converging to a steady horizontal ight. The calculation of the SRFE bounds yields the worst-case initial state corresponding to each control strategy. This information is used to compare alternative recovery strategies, determine their strengths and limitations, and identify the most e ective strategy. In regard to the control law, the authors developed feedback feedforward laws based on the gain scheduling of multivariable controllers. In regard to the command law, which is the mechanism governing the exogenous signals driving the feed- forward component of the controller, we developed laws with a feedback structure that combines local stability and transient response considera- tions. The upset recovery of the Generic Transport Model, a sub-scale twin-engine jet vehicle developed by NASA Langley Research Center, is used as a case study

    Cirrus Cloud Seeding has Potential to Cool Climate

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    Cirrus clouds, thin ice clouds in the upper troposphere, have a net warming effect on Earth s climate. Consequently, a reduction in cirrus cloud amount or optical thickness would cool the climate. Recent research indicates that by seeding cirrus clouds with particles that promote ice nucleation, their lifetimes and coverage could be reduced. We have tested this hypothesis in a global climate model with a state-of-the-art representation of cirrus clouds and find that cirrus cloud seeding has the potential to cancel the entire warming caused by human activity from pre-industrial times to present day. However, the desired effect is only obtained for seeding particle concentrations that lie within an optimal range. With lower than optimal particle concentrations, a seeding exercise would have no effect. Moreover, a higher than optimal concentration results in an over-seeding that could have the deleterious effect of prolonging cirrus lifetime and contributing to global warming

    Design optimization of RF lines in vacuum environment for the MITICA experiment

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    This contribution regards the Radio Frequency (RF) transmission line of the Megavolt ITER Injector and Concept Advancement (MITICA) experiment. The original design considered copper coaxial lines of 1″ 5/8, but thermal simulations under operating conditions showed maximum temperatures of the lines at regime not compatible with the prescription of the component manufacturer. Hence, an optimization of the design was necessary. Enhancing thermal radiation and increasing the conductor size were considered for design optimization: thermal analyses were carried out to calculate the temperature of MITICA RF lines during operation, as a function of the emissivity value and of other geometrical parameters. Five coating products to increase the conductor surface emissivity were tested, measuring the outgassing behavior of the selected products and the obtained emissivity values

    Neural correlates of working memory and its association with metabolic parameters in early-treated adults with phenylketonuria.

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    BACKGROUND Phenylketonuria (PKU) is an inborn error of metabolism affecting the conversion of phenylalanine (Phe) into tyrosine. Previous research has found cognitive and functional brain alterations in individuals with PKU even if treated early. However, little is known about working memory processing and its association with task performance and metabolic parameters. The aim of the present study was to examine neural correlates of working memory and its association with metabolic parameters in early-treated adults with PKU. METHODS This cross-sectional study included 20 early-treated adults with PKU (mean age: 31.4 years ± 9.0) and 40 healthy controls with comparable age, sex, and education (mean age: 29.8 years ± 8.2). All participants underwent functional magnetic resonance imaging (fMRI) of working memory to evaluate the fronto-parietal working memory network. Fasting blood samples were collected from the individuals with PKU to acquire a concurrent plasma amino acid profile, and retrospective Phe concentrations were obtained to estimate an index of dietary control. RESULTS On a cognitive level, early-treated adults with PKU displayed significantly lower accuracy but comparable reaction time in the working memory task compared to the control group. Whole-brain analyses did not reveal differences in working memory-related neural activation between the groups. Exploratory region-of-interest (ROI) analyses indicated reduced neural activation in the left and right middle frontal gyri and the right superior frontal gyrus in the PKU group compared to the control group. However, none of the ROI analyses survived correction for multiple comparisons. Neural activation was related to concurrent Phe, tyrosine, and tryptophan concentrations but not to retrospective Phe concentrations. CONCLUSION In early-treated adults with PKU, cognitive performance and neural activation are slightly altered, a result that is partly related to metabolic parameters. This study offers a rare insight into the complex interplay between metabolic parameters, neural activation, and cognitive performance in a sample of individuals with PKU

    Alternative complement pathway inhibition does not abrogate meningococcal killing by serum of vaccinated individuals

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    Dysregulation of complement activation causes a number of diseases, including paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome. These conditions can be treated with monoclonal antibodies (mAbs) that bind to the complement component C5 and prevent formation of the membrane attack complex (MAC). While MAC is involved in uncontrolled lysis of erythrocytes in these patients, it is also required for serum bactericidal activity (SBA), i.e. clearance of encapsulated bacteria. Therefore, terminal complement blockage in these patients increases the risk of invasive disease by Neisseria meningitidis more than 1000-fold compared to the general population, despite obligatory vaccination. It is assumed that alternative instead of terminal pathway inhibition reduces the risk of meningococcal disease in vaccinated individuals. To address this, we investigated the SBA with alternative pathway inhibitors. Serum was collected from adults before and after vaccination with a meningococcal serogroup A, C, W, Y capsule conjugate vaccine and tested for meningococcal killing in the presence of factor B and D, C3, C5 and MASP-2 inhibitors. B meningococci were not included in this study since the immune response against protein-based vaccines is more complex. Unsurprisingly, inhibition of C5 abrogated killing of meningococci by all sera. In contrast, both factor B and D inhibitors affected meningococcal killing in sera from individuals with low, but not with high bactericidal anti-capsular titers. While the anti-MASP-2 mAb did not impair SBA, inhibition of C3 impeded meningococcal killing in most, but not in all sera. These data provide evidence that vaccination can provide protection against invasive meningococcal disease in patients treated with alternative pathway inhibitors

    Inhibition of the different complement pathways has varying impacts on the serum bactericidal activity and opsonophagocytosis against Haemophilus influenzae type b

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    Defense against Haemophilus influenzae type b (Hib) is dependent on antibodies and complement, which mediate both serum bactericidal activity (SBA) and opsonophagocytosis. Here we evaluated the influence of capsule-specific antibodies and complement inhibitors targeting the central component C3, the alternative pathway (AP; fB, fD), the lectin pathway (LP; MASP-2) and the terminal pathway (C5) on both effector functions. Findings may be relevant for the treatment of certain diseases caused by dysregulation of the complement system, where inhibitors of complement factors C3 or C5 are used. Inhibitors against other complement components are being evaluated as potential alternative treatment options that may carry a reduced risk of infection by encapsulated bacteria. Serum and reconstituted blood of healthy adults were tested for bactericidal activity before and after vaccination with the Hib capsule-conjugate vaccine ActHIB. Most sera had bactericidal activity prior to vaccination, but vaccination significantly enhanced SBA titers. Independently of the vaccination status, both C3 and C5 inhibition abrogated SBA, whereas inhibition of the LP had no effect. AP inhibition had a major inhibitory effect on SBA of pre- vaccination serum, but vaccination mitigated this inhibition for all disease isolates tested. Despite this, SBA-mediated killing of some Hib isolates remained retarded. Even for the most serum-resistant isolate, SBA was the dominating defense mechanism in reconstituted whole blood, as addition of blood cells to the serum did not enhance bacterial killing. Limited Fc receptor-mediated opsonophagocytosis was unmasked when bacterial killing by the membrane attack complex was blocked. In the presence of C3 or C5 inhibitors, addition of post-vaccination, but not of pre-vaccination serum to the blood cells triggered opsonophagocytosis, leading to suppression of bacterial multiplication. Taken together, our data indicate that for host defense against Hib, killing by SBA is more efficient than by blood cell opsonophagocytosis. However, additional defense mechanisms, such as bacterial clearance by spleen and liver, may play an important role in preventing Hib-mediated sepsis, in particular for Hib isolates with increased serum-resistance. Results indicate potentially improved safety profile of AP inhibitors over C3 and C5 inhibitors as alternative therapeutic agents in patients with increased susceptibility to Hib infection

    Towards Using Reinforcement Learning for Autonomous Docking of Unmanned Surface Vehicles

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    Author's accepted manuscriptProviding full autonomy to Unmanned Surface Vehicles (USV) is a challenging goal to achieve. Autonomous docking is a subtask that is particularly difficult. The vessel has to distinguish between obstacles and the dock, and the obstacles can be either static or moving. This paper developed a simulator using Reinforcement Learning (RL) to approach the problem. We studied several scenarios for the task of docking a USV in a simulator environment. The scenarios were defined with different sensor inputs and start-stop procedures but a simple shared reward function. The results show that the system solved the task when the IMU (Inertial Measurement Unit) and GNSS (Global Navigation Satellite System) sensors were used to estimate the state, despite the simplicity of the reward function.acceptedVersio

    In vaccinated individuals serum bactericidal activity against B meningococci is abrogated by C5 inhibition but not by inhibition of the alternative complement pathway

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    INTRODUCTION: Several diseases caused by the dysregulation of complement activation can be treated with inhibitors of the complement components C5 and/or C3. However, complement is required for serum bactericidal activity (SBA) against encapsulated Gram-negative bacteria. Therefore, C3 and C5 inhibition increases the risk of invasive disease, in particular by Neisseria meningitidis. As inhibitors against complement components other than C3 and C5 may carry a reduced risk of infection, we compared the effect of inhibitors targeting the terminal pathway (C5), the central complement component C3, the alternative pathway (FB and FD), and the lectin pathway (MASP-2) on SBA against serogroup B meningococci. METHODS: Serum from adults was collected before and after vaccination with the meningococcal serogroup B vaccine 4CMenB and tested for meningococcal killing. Since the B capsular polysaccharide is structurally similar to certain human polysaccharides, 4CMenB was designed to elicit antibodies against meningococcal outer membrane proteins. RESULTS: While only a few pre-vaccination sera showed SBA against the tested B meningococcal isolates, 4CMenB vaccination induced potent complement-activating IgG titers against isolates expressing a matching allele of the bacterial cell surface-exposed factor H-binding protein (fHbp). SBA triggered by these cell surface protein-specific antibodies was blocked by C5 and reduced by C3 inhibition, whereas alternative (factor B and D) and lectin (MASP-2) pathway inhibitors had no effect on the SBA of post-4CMenB vaccination sera. DISCUSSION: Compared to the SBA triggered by A,C,W,Y capsule polysaccharide conjugate vaccination, SBA against B meningococci expressing a matching fHbp allele was remarkably resilient against the alternative pathway inhibition

    Evaluating climate geoengineering proposals in the context of the Paris Agreement temperature goals

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    Current mitigation efforts and existing future commitments are inadequate to accomplish the Paris Agreement temperature goals. In light of this, research and debate are intensifying on the possibilities of additionally employing proposed climate geoengineering technologies, either through atmospheric carbon dioxide removal or farther-reaching interventions altering the Earth’s radiative energy budget. Although research indicates that several techniques may eventually have the physical potential to contribute to limiting climate change, all are in early stages of development, involve substantial uncertainties and risks, and raise ethical and governance dilemmas. Based on present knowledge, climate geoengineering techniques cannot be relied on to significantly contribute to meeting the Paris Agreement temperature goals
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