Zobrazeno 1 - 10
of 451
pro vyhledávání: '"Ivanov Stefan"'
We consider certain fiber bundles over a paraquaternionic contact manifolds, called twistor and reflector spaces, and show that these carry an intrinsic geometric structure that is always integrable.
Externí odkaz:
http://arxiv.org/abs/2409.00539
Publikováno v:
Cybernetics and Information Technologies, Vol 20, Iss 6, Pp 140-154 (2020)
Alzheimer’s Disease (AD) is a neurodegenerative disorder with severe consequences and lethal outcome. One of the pathological hallmarks of the disease is the formation of insoluble intercellular beta-Amyloid (Aβ) plaques. The enzyme ACetylcholinEs
Externí odkaz:
https://doaj.org/article/062c886a1a0f4bf49631afdf02c34bae
Publikováno v:
Cybernetics and Information Technologies, Vol 20, Iss 6, Pp 194-200 (2020)
The AutoImmune ThyroiDitis (AITD), known as Hashimoto’s disease, is a chronic autoimmune thyroid disease progressively developed to hypothyroidism. The AITD is characterized by the formation of autoantibodies targeting two specific thyroid antigens
Externí odkaz:
https://doaj.org/article/893bf153f4544343b6799024a929f98d
Autor:
Ivanov, Stefan, Petkov, Alexander
We establish in the present paper two sub-gradient estimates for the quaternionic contact (qc) heat equation on a compact qc manifold of dimension $4n+3$, provided some positivity conditions are satisfied. These are qc versions of the prominent Li-Ya
Externí odkaz:
http://arxiv.org/abs/2405.14845
We introduce the notion of paraquaternionic contact structures (pqc structures), which turns out to be a generalization of the para 3-Sasakian geometry. We derive a distinguished linear connection preserving the pqc structure. Its torsion tensor is e
Externí odkaz:
http://arxiv.org/abs/2404.16713
A tensor invariant is defined on a paraquaternionic contact manifold in terms of the curvature and torsion of the canonical paraquaternionic connection involving derivatives up to third order of the contact form. This tensor, called paraquaternionic
Externí odkaz:
http://arxiv.org/abs/2404.16703
Autor:
Ivanov, Stefan, Petkov, Alexander
Curvature properties of the characteristic connection on an integrable $G_2$ space are investigated. It is proved that an integrable $G_2$ manifold has closed torsion if and only if the Ricci tensor of the characteristic connection is equal to the co
Externí odkaz:
http://arxiv.org/abs/2307.06438
Autor:
Ivanov, Stefan, Stanchev, Nikola
It is observed that on a compact almost complex Calabi-Yau with torsion 6-manifold the Nijenhuis tensor is parallel with respect to the torsion connection. If the torsion is closed then the space is a compact generalized gradient Ricci soliton. In th
Externí odkaz:
http://arxiv.org/abs/2307.05001
Autor:
Ivanov, Stefan, Stanchev, Nikola
Curvature properties of the characteristic connection on an integrable $G_2$ manifold are investigated. We consider integrable $G_2$ manifold of constant type, i.e. the scalar product of the exterior derivative of the $G_2$ form with its Hodge dual i
Externí odkaz:
http://arxiv.org/abs/2307.05619