80 research outputs found

    Generalizations of a method for constructing first integrals of a class of natural Hamiltonians and some remarks about quantization

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    In previous papers we determined necessary and sufficient conditions for the existence of a class of natural Hamiltonians with non-trivial first integrals of arbitrarily high degree in the momenta. Such Hamiltonians were characterized as (n+1)-dimensional extensions of n-dimensional Hamiltonians on constant-curvature (pseudo-)Riemannian manifolds Q. In this paper, we generalize that approach in various directions, we obtain an explicit expression for the first integrals, holding on the more general case of Hamiltonians on Poisson manifolds, and show how the construction of above is made possible by the existence on Q of particular conformal Killing tensors or, equivalently, particular conformal master symmetries of the geodesic equations. Finally, we consider the problem of Laplace-Beltrami quantization of these first integrals when they are of second-degree.Comment: Presented at the conference Quantum Theory and Symmetries 7, Praha, August 7-13 2011. In v2 some typos corrected, a comment added after eq. (4), a comment about ref. [1] correcte

    Geometrical classification of Killing tensors on bidimensional flat manifolds

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    Valence two Killing tensors in the Euclidean and Minkowski planes are classified under the action of the group which preserves the type of the corresponding Killing web. The classification is based on an analysis of the system of determining partial differential equations for the group invariants and is entirely algebraic. The approach allows to classify both characteristic and non characteristic Killing tensors.Comment: 27 pages, 20 figures, pictures format changed to .eps, typos correcte

    Evaluation of the Efficiency of Some Antagonistic Trichoderma spp. in the Management of Plant Parasitic Nematodes

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    Plant parasitic nematodes cause great economic losses to agricultural crops worldwide. They along, with their hosts, are not isolated in the ecological system, but are strongly influenced by antagonists, parasites and pathogens. Though pesticides appear to be the most economical and efficacious means of controlling plant pathogens, toxicological, environmental and sociological concerns have led to drastic reductions in the availability of efficient commercial nematicides. These restrictions have forced farmers to look for an integral system that makes use of other means of disease control. Species of spiral nematodes, Helicotylenchus and Scutellonema, were among the most abundant plant parasitic nematodes of the mulberry plant. Eco-friendly control of the parasitic nematodes could be achieved by means of endoparasitic fungi (like Hirsutella, Meria, Nematophthora and Nematoctonus), trapping fungi (like Arthrobotrys and Duddingtonia) or parasitic fungi (like Paeceilomyces lilacinus). During the course of this present work, Trichoderma Pers. Ex. Fr. was found to be one of the most effective fungi in controlling the eggs and J2 of Meloidogyne javanica. The present study outlines the comparative efficacy of five Trichoderma species (T. viride, T. harzianum, T. longibrachiatum, T. koningii and T. hamatum) against Helicotylenchus sp. and Scutellonema sp. The study also outlines the effect of Trichoderma viride Persoon on Scutellonema spp. and Helicotylenchus sp., effect of Trichoderma harzianum Raifae on Scutellonema sp. and Helicotylenchus sp., effect of Trichoderma longibrachiatum Rifai on Scutellonema sp. and Helicotylenchus sp., effect of Trichoderma koningii Oudeom on Scutellonema sp. and Helicotylenchus sp., and lastly effect of Trichoderma hamatum (Bonord) Bainier on Scutellonema sp. and Helicotylenchus sp

    A modified Delphi approach to develop a trial protocol for antibiotic de-escalation in patients with suspected sepsis

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    Background: Early administration of antibiotics in sepsis is associated with improved patient outcomes, but safe and generalizable approaches to de-escalate or discontinue antibiotics after suspected sepsis events are unknown. Methods: We used a modified Delphi approach to identify safety criteria for an opt-out protocol to guide de-escalation or discontinuation of antibiotic therapy after 72 hours in non-ICU patients with suspected sepsis. An expert panel with expertise in antimicrobial stewardship and hospital epidemiology rated 48 unique criteria across 3 electronic survey rating tools. Criteria were rated primarily based on their impact on patient safety and feasibility for extraction from electronic health record review. The 48 unique criteria were rated by anonymous electronic survey tools, and the results were fed back to the expert panel participants. Consensus was achieved to either retain or remove each criterion. Results: After 3 rounds, 22 unique criteria remained as part of the opt-out safety checklist. These criteria included high-risk comorbidities, signs of severe illness, lack of cultures during sepsis work-up or antibiotic use prior to blood cultures, or ongoing signs and symptoms of infection. Conclusions: The modified Delphi approach is a useful method to achieve expert-level consensus in the absence of evidence suifficient to provide validated guidance. The Delphi approach allowed for flexibility in development of an opt-out trial protocol for sepsis antibiotic de-escalation. The utility of this protocol should be evaluated in a randomized controlled trial

    Directing cell therapy to anatomic target sites in vivo with magnetic resonance targeting

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    Cell-based therapy exploits modified human cells to treat diseases but its targeted application in specific tissues, particularly those lying deep in the body where direct injection is not possible, has been problematic. Here we use a magnetic resonance imaging (MRI) system to direct macrophages carrying an oncolytic virus, Seprehvir, into primary and metastatic tumour sites in mice. To achieve this, we magnetically label macrophages with super-paramagnetic iron oxide nanoparticles and apply pulsed magnetic field gradients in the direction of the tumour sites. Magnetic resonance targeting guides macrophages from the bloodstream into tumours, resulting in increased tumour macrophage infiltration and reduction in tumour burden and metastasis. Our study indicates that clinical MRI scanners can not only track the location of magnetically labelled cells but also have the potential to steer them into one or more target tissues

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    Not AvailableThe contribution of non timber forest products (NTFPs) has been recognized as an important element for achieving food security, diversifying income sources and generating ecosystem services. In forest landscape of India, non-timber forest products, which benefit the livelihoods of many people, is in threat due to many reasons such as over exploitation, deforestation, climate change, etc. In this context, use of remote sensing technologies can be considered as reliable and quick tools in mapping to improve the sustainable utilization of NTFPs.Not Availabl
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