1,090 research outputs found

    Alfalfa mosaic virus: Occurrence and variation among isolates from forage legumes in Ethiopia

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    Filed samples and seedlings of 51 leguminous forage species were tested for alfalfa mosaic virus (AMV) in routine monitoring of seed multiplication fields of the International Livestock Research Institute (ILRI), Ethiopia. The virus was detected in 24 species and a solanaceous weed Solanum nigrum. Of these, the following 17 species are being reported for the first time as hosts of the virus in world literature: Aeschynomene falcata, Centrosema pascuorum, Chamaecrista rotundifolia, Desmanthus virgatus, Desmodium intortum, Leucaena leucocephala, Macroptilium atropurpureum, Macroptilium lathyroides, Macrotyloma axillare, Medicago truncatula, Neonotonia wightii, Sesbania sesban, Stylosanthes scabra, Trifolium calocephala, T. steudneri, T. tembense and Vigna parkeri. The solanaceous weed S. nigrum was suspected to play a role in the virus epidemiology. The level of seed infection varied from 0.00 percent to about 13.00 percent. Infectivity studies on 5 isolates of the virus revealed heterogeneity in prevalent AMV isolates. Two major strains were identified, based on the development of necrotic local lesions on Vigna unguiculata accessions. One of the isolates which failed to incite local necrotic lesions on unguiculata infected Phaseolus vulgaris cTop Crop systematically. Differences among isolates were also noticed in their concentration in different hosts as indicated by ELISA absorbance values

    Responses of vascular plant fine roots and associated microbial communities to whole-ecosystem warming and elevated CO2 in northern peatlands

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    Warming and elevated CO2 (eCO2) are expected to facilitate vascular plant encroachment in peatlands. The rhizosphere, where microbial activity is fueled by root turnover and exudates, plays a crucial role in biogeochemical cycling, and will likely at least partially dictate the response of the belowground carbon cycle to climate changes. We leveraged the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment, to explore the effects of a whole-ecosystem warming gradient (+0°C to 9°C) and eCO2 on vascular plant fine roots and their associated microbes. We combined trait-based approaches with the profiling of fungal and prokaryote communities in plant roots and rhizospheres, through amplicon sequencing. Warming promoted self-reliance for resource uptake in trees and shrubs, while saprophytic fungi and putative chemoorganoheterotrophic bacteria utilizing plant-derived carbon substrates were favored in the root zone. Conversely, eCO2 promoted associations between trees and ectomycorrhizal fungi. Trees mostly associated with short-distance exploration-type fungi that preferentially use labile soil N. Additionally, eCO2 decreased the relative abundance of saprotrophs in tree roots. Our results indicate that plant fine-root trait variation is a crucial mechanism through which vascular plants in peatlands respond to climate change via their influence on microbial communities that regulate biogeochemical cycles

    Healthcare satisfaction in older and younger patients with cancer

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    Objective Although older patients represent the most rapidly growing segment of the oncology population, clinical care is guided by very little data on patient-reported outcomes, particularly satisfaction with healthcare. Using a large cancer center registry, we sought to describe factors associated with satisfaction with care for older and younger oncology patients. Methods Data were collected through the University of North Carolina Health Registry Cancer Survivorship Cohort. Satisfaction was measured with the Patient Satisfaction Questionnaire Short Form. Quality of life (QOL) measures included were the Promis Global short form and the Functional Assessment of Cancer Therapy General (FACT-G). Results A total of 2385 patients were included. 460 (20%) were aged 70 and above (older group). Older patients reported significantly higher levels of satisfaction in domains of time spent with doctor (scores 3.84 versus 3.73 p = 0.03) and financial aspects (scores 4.03 versus 3.44 p < 0.001) compared to younger patients. In multivariable analysis, higher QOL scores and higher self-reported ECOG performance status were associated with higher satisfaction scores. African American race was associated with lower satisfaction scores in all age groups. QOL was more closely correlated with satisfaction in older patients compared to younger patients. Conclusions Older patients with cancer report higher levels of satisfaction with care, in part due to lesser financial burden of care. Better QOL is associated with satisfaction with care in older patients. Use of patient-reported outcomes such as patient satisfaction may help improve patient-centered geriatric oncology care

    On Verification of the Non-Generational Conjectural- Derivation of First Class constraints: HP Monopole's Field case

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    In [7] we proposed a non-generational conjectural derivation of all first class constraints (involving, only, variables compatible with canonical Poisson brackets) for realistic gauge (singular) field theories; and we verified the conjecture in cases of electromagnetic field, Yang Mills fields interacting with scalar and spinor fields, and the gravitational field. Here we will further verify our conjecture for the case of 't Hooft- Polyakov (HP) monopole's field (i.e. in the Higgs Vacuum); and show that we will reproduce the results in Ref.[6], which we reached at using Dirac's standard multi-generational algorithm

    On the covariant quantization of tensionless bosonic strings in AdS spacetime

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    The covariant quantization of the tensionless free bosonic (open and closed) strings in AdS spaces is obtained. This is done by representing the AdS space as an hyperboloid in a flat auxiliary space and by studying the resulting string constrained hamiltonian system in the tensionless limit. It turns out that the constraint algebra simplifies in the tensionless case in such a way that the closed BRST quantization can be formulated and the theory admits then an explicit covariant quantization scheme. This holds for any value of the dimension of the AdS space.Comment: 1+16 pages; v4 two clarifications adde

    Detecting a stochastic gravitational wave background with the Laser Interferometer Space Antenna

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    The random superposition of many weak sources will produce a stochastic background of gravitational waves that may dominate the response of the LISA (Laser Interferometer Space Antenna) gravitational wave observatory. Unless something can be done to distinguish between a stochastic background and detector noise, the two will combine to form an effective noise floor for the detector. Two methods have been proposed to solve this problem. The first is to cross-correlate the output of two independent interferometers. The second is an ingenious scheme for monitoring the instrument noise by operating LISA as a Sagnac interferometer. Here we derive the optimal orbital alignment for cross-correlating a pair of LISA detectors, and provide the first analytic derivation of the Sagnac sensitivity curve.Comment: 9 pages, 11 figures. Significant changes to the noise estimate

    The Hamiltonian formulation of General Relativity: myths and reality

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    A conventional wisdom often perpetuated in the literature states that: (i) a 3+1 decomposition of space-time into space and time is synonymous with the canonical treatment and this decomposition is essential for any Hamiltonian formulation of General Relativity (GR); (ii) the canonical treatment unavoidably breaks the symmetry between space and time in GR and the resulting algebra of constraints is not the algebra of four-dimensional diffeomorphism; (iii) according to some authors this algebra allows one to derive only spatial diffeomorphism or, according to others, a specific field-dependent and non-covariant four-dimensional diffeomorphism; (iv) the analyses of Dirac [Proc. Roy. Soc. A 246 (1958) 333] and of ADM [Arnowitt, Deser and Misner, in "Gravitation: An Introduction to Current Research" (1962) 227] of the canonical structure of GR are equivalent. We provide some general reasons why these statements should be questioned. Points (i-iii) have been shown to be incorrect in [Kiriushcheva et al., Phys. Lett. A 372 (2008) 5101] and now we thoroughly re-examine all steps of the Dirac Hamiltonian formulation of GR. We show that points (i-iii) above cannot be attributed to the Dirac Hamiltonian formulation of GR. We also demonstrate that ADM and Dirac formulations are related by a transformation of phase-space variables from the metric gμνg_{\mu\nu} to lapse and shift functions and the three-metric gkmg_{km}, which is not canonical. This proves that point (iv) is incorrect. Points (i-iii) are mere consequences of using a non-canonical change of variables and are not an intrinsic property of either the Hamilton-Dirac approach to constrained systems or Einstein's theory itself.Comment: References are added and updated, Introduction is extended, Subsection 3.5 is added, 83 pages; corresponds to the published versio
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