Yang-Mills instantons and dyons on homogeneous G_2-manifolds

We consider Lie G-valued Yang-Mills fields on the space R x G/H, where G/H is a compact nearly K"ahler six-dimensional homogeneous space, and the manifold R x G/H carries a G_2-structure. After imposing a general G-invariance condition, Yang-Mills theory with torsion on R x G/H is reduced to Newtonian mechanics of a particle moving in R^6, R^4 or R^2 under the influence of an inverted double-well-type potential for the cases G/H = SU(3)/U(1)xU(1), Sp(2)/Sp(1)xU(1) or G_2/SU(3), respectively. We analyze all critical points and present analytical and numerical kink- and bounce-type solutions, which yield G-invariant instanton configurations on those cosets. Periodic solutions on S^1 x G/H and dyons on iR x G/H are also given.Comment: 1+26 pages, 14 figures, 6 miniplot

Sustainable Fertilization in Medicinal and Aromatic Plants

The nutrient level in the soil is one of the most investigated aspects of agricultural research, also including research into Medicinal and Aromatic plants. The effect of fertilization has been studied in detail for many species, with contrasting results as concerns above all the qualitative aspects of production. Generally speaking, an increased level of nutrients induces an enhancement of plant biomass, but when the goal of cultivation is different from herbage yield, i.e. when a special plant part (seeds, or roots, or flowers) is of interest, or when the quality features are especially important, the outcome of fertilization may be dramatically different. A fine-tuned fertilization practice is therefore necessary, and forms, rates and times of distribution of fertilizers must be accurately planned and managed

Human papillomavirus infection in oral verrucous carcinoma: genotyping analysis and inverse correlation with p53 expression.

OBJECTIVE: Verrucous carcinoma (VC) is a rare subtype of squamous cell carcinoma, occurring mostly in oral mucosa. To clarify the role of human papillomavirus (HPV) in VC tumorigenesis, we investigated localization and genotypes of HPV and p53 expression in oral VC. METHODS: We studied paraffin-embedded specimens of 23 VCs and 10 control non-neoplastic lesions in oral mucosa. To investigate HPV infection, HPV genotypes and p53 expression, we respectively employed in situ hybridization (ISH), sequence analysis following short PCR fragment-PCR assay and immunohistochemistry. RESULTS: Of the 23 VC specimens, 11 (48%) had HPV-DNA (detectable by PCR), and 6 (26%) had intranuclear HPV in the upper portion of the squamous epithelium (detectable by ISH). Nine of the 11 PCR-positive specimens showed multiple infections with low- and high-risk HPVs. No HPV-16 infection was detected. Although HPV-6 and HPV-18 were frequently detected by PCR, no HPV could be found in control specimens by ISH. p53 expression was inversely correlated with HPV infection. CONCLUSION: Thus, multiple infections with low- and high-risk HPVs and their rapid replication during hyperkeratinization may participate in the histogenesis of oral VC. Oral VC tumorigenesis may involve the inactivation of p53, which is associated with HPV infection