979 research outputs found

    Below ground efficiency of a parasitic wasp for Drosophila suzukii biocontrol in different soil types

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    The parasitoid wasp Trichopria drosophilae is promising as a biocontrol agent for controlling the ubiquitous pest Drosophila suzukii (Matsumura). Crucial for the successful implementation of any biocontrol agent is a high parasitisation rate by the parasitoid. Most studies investigating the parasitisation rate of D. suzukii pupae have focused on parasitisation in the fruit or in a petri dish. However, the predominant pupation site of D. suzukii in the field is the soil. Unfortunately, little is known on how well parasitoid wasps can detect and parasitise pupae of D. suzukii buried in the soil. Therefore, we conducted soil parasitisation experiments of T. drosophilae on D. suzukii pupae using two pupation depths in three different soil types (loamy sand, loam, and clay). In all three soil types, we found generally low D. suzukii pupae parasitisation rate by T. drosophilae, independent of the pupation depth. The pupation behaviour of D. suzukii and the parasitisation behaviour of T. drosophilae are discussed in detail. For pest control in most soil types, our results mean that the number of D. suzukii larvae pupating in the soil should be reduced, e.g., by adding a layer of sandy soil or covering the soil with plastic mulch. This might increase the probability of success when using T. drosophilae as a biocontrol agent

    Space-based geoengineering: challenges and requirements

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    The prospect of engineering the Earth's climate (geoengineering) raises a multitude of issues associated with climatology, engineering on macroscopic scales, and indeed the ethics of such ventures. Depending on personal views, such large-scale engineering is either an obvious necessity for the deep future, or yet another example of human conceit. In this article a simple climate model will be used to estimate requirements for engineering the Earth's climate, principally using space-based geoengineering. Active cooling of the climate to mitigate anthropogenic climate change due to a doubling of the carbon dioxide concentration in the Earth's atmosphere is considered. This representative scenario will allow the scale of the engineering challenge to be determined. It will be argued that simple occulting discs at the interior Lagrange point may represent a less complex solution than concepts for highly engineered refracting discs proposed recently. While engineering on macroscopic scales can appear formidable, emerging capabilities may allow such ventures to be seriously considered in the long term. This article is not an exhaustive review of geoengineering, but aims to provide a foretaste of the future opportunities, challenges, and requirements for space-based geoengineering ventures

    Lithium motion in the anode material LiC6 as seen via time-domain 7Li NMR

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    Since the commercialization of rechargeable lithium-ion energy storage systems in the early 1990s, graphite intercalation compounds (GICs) have served as the number one negative electrode material in most of today's batteries. During charging the performance of a battery is closely tied with facile Li insertion into the graphite host structure. So far, only occasionally time-domain nuclear magnetic resonance (NMR) measurements have been reported to study Li self-diffusion parameters in GICs. Here, we used several NMR techniques to enlighten Li hopping motions from an atomic-scale point of view. Li self-diffusion in the stage-1 GIC LiC6 has been studied comparatively by temperature-variable spin-spin relaxation NMR as well as (rotating frame) spin-lattice relaxation NMR. The data collected yield information on both the relevant activation energies and jump rates, which can directly be transformed into Li self-diffusion coefficients. At room temperature the Li self-diffusion coefficient turns out to be 10−15m2s−1, thus, slightly lower than that for layer-structured cathode materials such as Lix≈0.7TiS2. © 2013 American Physical Society

    Impairment of Procedural Learning and Motor Intracortical Inhibition in Neurofibromatosis Type 1 Patients

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    AbstractBackgroundCognitive difficulties are the most common neurological complications in neurofibromatosis type 1 (NF1) patients. Recent animal models proposed increased GABA-mediated inhibition as one underlying mechanism directly affecting the induction of long-term potentiation (LTP) and learning. In most adult NF1 patients, apparent cognitive and attentional deficits, tumors affecting the nervous system and other confounding factors for neuroscientific studies are difficult to control for. Here we used a highly specific group of adult NF1 patients without cognitive or nervous system impairments. Such selected NF1 patients allowed us to address the following open questions: Is the learning process of acquiring a challenging motor skill impaired in NF1 patients? And is such an impairment in relation to differences in intracortical inhibition?MethodsWe used an established non-invasive, double-pulse transcranial magnetic stimulation (dp-TMS) paradigm to assess practice-related modulation of intracortical inhibition, possibly mediated by gamma-minobutyric acid (GABA)ergic-neurotransmission. This was done during an extended learning paradigm in a group of NF1 patients without any neuropsychological deficits, functioning normally in daily life and compared them to healthy age-matched controls.FindingsNF1 patients experienced substantial decline in motor skill acquisition (F=9.2, p=0.008) over five-consecutives training days mediated through a selective reduction in the early acquisition (online) and the consolidation (offline) phase. Furthermore, there was a consistent decrease in task-related intracortical inhibition as a function of the magnitude of learning (T=2.8, p=0.014), especially evident after the early acquisition phase.InterpretationsCollectively, the present results provide evidence that learning of a motor skill is impaired even in clinically intact NF1 patients based, at least partially, on a GABAergic-cortical dysfunctioning as suggested in previous animal work

    Manganese compounds with phthalate and terephthalate ligands: Synthesis, crystal structure, magnetic properties and catalase activity

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    The reactivity of carboxybenzoic acids substituted in ortho, meta and para positions (phthalic, isophthalic and terephthalic acids) has been explored. These acids have been used for the synthesis of dinuclear MnIII and polynuclear MnII compounds, obtaining unexpected results. From all the reactions, one dinuclear MnIII compound, [{Mn(H2O)(phen)}2(l-2-COOHC6H4COO)2(l-O)](ClO4)2 (1), one mixed valence compound, [{Mn(phen)2}2(l-O)2](NO3)3 (2), and four MnII compounds, [{Mn(H2O)(phen)2}2(l-4-COOC6H4- COO)](NO3)2 (3), [Mn3(l-4-COOC6H4COO)3(bpy)2]n (4), [{Mn(phen)2}2(l-2-COOHC6H4COO)2](ClO4)2 (5) and [Mn(l-2-COOC6H4COO)(H2O)2(phen)]n (6), (phen = 1,10-phenanthroline, bpy = 2,20-bipyridine) have been obtained and characterised by X-ray diffraction, showing different coordination modes for the carboxylate ligand: a bidentate bridge in a syn syn, syn-anti or anti-anti mode, a bis-monodentate bridge and a bis-bidentate bridge. The six compounds show antiferromagnetic coupling, with magnetic interaction constants of 3.7 and 332.5 cm 1 for the dinuclear MnIII (1) and MnIIIMnIV (2) compounds and 0.04, 4.5, 1.5 and 0.55 cm 1 for MnII compounds 4-6. Each MnII compound shows a different EPR spectrum at 4 K, which has been simulated including the ZFS parameters. The catalase activity of the compounds with phthalate and terephthalate ligands has been studied, the former being less active than the latter

    Immunization with recombinant FliD confers protection against Helicobacter pylori infection in mice

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    Nearly half of the world's population is infected with Helicobacter pylori. Clinical manifestations of this infection range from gastritis and peptic ulcers to gastric adenocarcinoma and lymphoma. Due to the emerging of antibiotic resistant strains and poor patient compliance of the antibiotic therapy, there is increasing interest in the development of a protective vaccine against H. pylori infection. The bacterial protein FliD forms a capping structure on the end of each flagellum which is critical to prevent depolymerization and structural degradation. In this study, the potential of FliD as a prospective H. pylori subunit vaccine was assessed. For this purpose, immunogenicity and protective efficacy of recombinant FliD (rFliD) from H. pylori was evaluated in C57BL/6 mice. Purified rFliD was formulated with different adjuvants and administered via subcutaneous or oral route. Subcutaneous immunization with rFliD elicited predominantly mixed Th1 and Th17 immune responses, with high titers of specific IgG 1 and IgG 2a . Splenocytes of immunized mice exhibited strong antigen-specific memory responses, resulting in the secretion of high amounts of IFN-γ and IL-17, and low levels of IL-4. Immunization with rFliD caused a significant reduction in H. pylori bacterial load relative to naïve control mice (p < 0.001), demonstrating a robust protective effect. Taken together, these results suggest that subcutaneous vaccination with rFliD formulated with CpG or Addavax could be considered as a potential candidate for the development of a subunit vaccine against H. pylori infection. © 2018 Elsevier Lt
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