457 research outputs found

    Elastic Scattering of Neutrinos off Polarized Electrons

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    We calculate the cross sections for elastic nu_l + e -> nu_l + e and antinu_l + e -> antinu_l + e scattering (l=e, mu or tau) in the Born approximation and with exactly fixed polarization states of target and final-state electrons, discussing their sensitivity to the incident (anti)neutrino flavor. We suggest investigation of the flavor composition of a (anti)neutrino beam by a flux-independent analysis of the scattering of its constituents off polarized electrons.Comment: 6 pages, 2 figure

    The Role of M(W) in Precision Studies of the Standard Model

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    Recent calculations have significantly decreased the scheme and residual scale dependence of basic radiative corrections of the Standard Electroweak Model. This leads to a theoretically accurate prediction of the W-boson mass M(W), as well as a reduced upper bound for the Higgs boson mass M(H). The implications of a precise M(W) measurement on the M(H) estimate are emphasized.Comment: 8 pages, LaTeX. One reference and one paragraph added. Conclusions unchanged. To be published in Physics Letters

    A New Renormalization Scheme of Fermion Fields in Electroweak Standard Model

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    This paper has been withdrawn by the author,due a immature idea.Comment: 6 page

    A Guide to Cannabis Virology: From the Virome Investigation to the Development of Viral Biotechnological Tools

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    Cannabis sativa cultivation is experiencing a period of renewed interest due to the new opportunities for its use in different sectors including food, techno-industrial, construction, pharmaceutical and medical, cosmetics, and textiles. Moreover, its properties as a carbon sequestrator and soil improver make it suitable for sustainable agriculture and climate change mitigation strategies. The increase in cannabis cultivation is generating conditions for the spread of new pathogens. While cannabis fungal and bacterial diseases are better known and characterized, viral infections have historically been less investigated. Many viral infection reports on cannabis have recently been released, highlighting the increasing threat and spread of known and unknown viruses. However, the available information on these pathogens is still incomplete and fragmentary, and it is therefore useful to organize it into a single structured document to provide guidance to growers, breeders, and academic researchers. This review aims to present the historical excursus of cannabis virology, from the pioneering descriptions of virus-like symptoms in the 1940s/50s to the most recent high-throughput sequencing reports. Each of these viruses detected in cannabis will be categorized with an increasing degree of threat according to its potential risk to the crop. Lastly, the development of viral vectors for functional genetics studies will be described, revealing how cannabis virology is evolving not only for the characterization of its virome but also for the development of biotechnological tools for the genetic improvement of this crop

    Elimination of Threshold Singularities in the Relation Between On-Shell and Pole Widths

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    In a previous communication by two of us, Phys. Rev. Lett. 81, 1373 (1998), the gauge-dependent deviations of the on-shell mass and total decay width from their gauge-independent pole counterparts were investigated at leading order for the Higgs boson of the Standard Model. In the case of the widths, the deviation was found to diverge at unphysical thresholds, m_H = 2 root{xi_V} m_V (V = W,Z), in the R_xi gauge. In this Brief Report, we demonstrate that these unphysical threshold singularities are properly eliminated if a recently proposed definition of wave-function renormalization for unstable particles is invoked.Comment: 8 pages (Latex), 1 figure (Postscript

    Molecular typing of bois noir phytoplasma strains in the chianti classico area (Tuscany, Central Italy) and their association with symptom severity in vitis vinifera 'sangiovese'

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    Bois noir (BN) is the most widespread disease of the grapevine yellows complex in the Euro-Mediterranean area. BN is caused by 'Candidatus Phytoplasma solani' (BNP), transmitted from herbaceous plants to grapevine by polyphagous insect vectors. In this study, genetic diversity among BNP strains and their prevalence and possible association with grapevine symptom severity were investigated in a Sangiovese clone organic vineyard in the Chianti Classico area (Tuscany). Field surveys over 2 years revealed a range of symptom severity on grapevine and an increase of BN incidence. ATaqMan allelic discrimination assay detected only tufB type b among BNP strains, suggesting the prevalence of the bindweed-related ecology. Nucleotide sequence analyses of vmp1 and stamp genes identified 12 vmp1 and 16 stamp sequence variants, showing an overall positive selection for such genes. The prevalent genotype was Vm43/St10, reported for the first time in this study and closely related to strains identified only in the French Eastern Pyrenees. BNP strains identified in the examined vineyard and mostly grouped in separate bindweed-related phylogenetic clusters showed statistically significant differences in their distribution in grapevines exhibiting distinct symptom severity. These results suggest the possible occurrence of a range of virulence within BNP strain populations in the Chianti Classico area

    Towards nutrition-sensitive agriculture : an evaluation of biocontrol effects, nutritional value, and ecological impact of bacterial inoculants

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    Nutrition-Sensitive Agriculture (NSA) is a novel concept in agriculture that considers not only yield, but also nutritional value of produce, sustainability of production, and ecological impact of agriculture. In accordance with its goals, NSA would benefit from applying microbial-based products as they are deemed more sustainable than their synthetic counterparts. This study characterized 3 plant-beneficial bacterial strains (Paenibacillus pasadenensis strain R16, Pseudomonas syringae strain 260-02, Bacillus amyloliquefaciens strain CC2) on their biocontrol activity and effect on nutritional and texture quality of romaine lettuce plants (Lactuca sativa) in greenhouse. The pathogens used in the trials are Rhizoctonia solani and Pythium ultimum. The obtained results indicate that strain R16 had a significant ability to cause a statistically significant reduction in the symptoms caused by both P. ultimum ( reduction of 32%) and R. solani (reduction of 42%), while the other two strains showed a less efficient biocontrol ability. Indices of the nutritional quality (content in phenols, carotenoids and chlorophyll) were unaffected by the treatments, indicating that the product was equivalent to that obtained without using the bacteria, while the texture of the leaves benefits from the biocontrol treatments. In particular, the mechanical resistance of the leaves was significantly higher in non-treated plants affected by R. solani but was restored to the values of healthy plants when the bacterial inoculants were present as well. The ecological impact was evaluated by characterizing the bacterial microbiota in bulk soil, rhizosphere, and root in the presence or absence of the inoculants. The composition of the microbiota, analyzed with a Unifrac model to describe beta-diversity, was radically different in the rhizosphere and the root endosphere among treatments, while the bulk soil formed a single cluster regardless of treatment, indicating that the use of these treatments did not have an ecological impact outside of the plant
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