Non-Integrability of Some Higher-Order Painlev\'e Equations in the Sense of Liouville

In this paper we study the equation $$w^{(4)} = 5 w" (w^2 - w') + 5 w (w')^2 - w^5 + (\lambda z + \alpha)w + \gamma,$$ which is one of the higher-order Painlev\'e equations (i.e., equations in the polynomial class having the Painlev\'e property). Like the classical Painlev\'e equations, this equation admits a Hamiltonian formulation, B\"acklund transformations and families of rational and special functions. We prove that this equation considered as a Hamiltonian system with parameters $\gamma/\lambda = 3 k$, $\gamma/\lambda = 3 k - 1$, $k \in \mathbb{Z}$, is not integrable in Liouville sense by means of rational first integrals. To do that we use the Ziglin-Morales-Ruiz-Ramis approach. Then we study the integrability of the second and third members of the $\mathrm{P}_{\mathrm{II}}$-hierarchy. Again as in the previous case it turns out that the normal variational equations are particular cases of the generalized confluent hypergeometric equations whose differential Galois groups are non-commutative and hence, they are obstructions to integrability

On the integrability of a system describing the stationary solutions in Bose--Fermi mixtures

We study the integrability of a Hamiltonian system describing the stationary solutions in Bose--Fermi mixtures in one dimensional optical lattices. We prove that the system is integrable only when it is separable. The proof is based on the Differential Galois approach and Ziglin-Morales-Ramis method.Comment: 21 page

Gard – An Intelligent System for Distributed Exploration of Landmine Fields Simulated by a Team of Khepera Robots

Manolov O, Iske B, Noykov S, et al. Gard – An Intelligent System for Distributed Exploration of Landmine Fields Simulated by a Team of Khepera Robots. In: Proceedings of the International Conference Automatics and Informatics’03. Vol 1. Sofia, Bulgaria; 2003: 199-202

Gard – An Intelligent System for Distributed Exploration of Landmine Fields Simulated by a Team of Khepera Robots

Manolov O, Iske B, Noykov S, et al. Gard – An Intelligent System for Distributed Exploration of Landmine Fields Simulated by a Team of Khepera Robots. In: Proceedings of the International Conference Automatics and Informatics’03. Vol 1. Sofia, Bulgaria; 2003: 199-202

[Reviews] Endocrine aspects of obstructive sleep apnea

publisher[Abstract] Obstructive sleep apnea (OSA) is a common clinical condition that has variety of adverse effects on human health. Studies suggest that OSA increases the cardiovascular risk, and a link between OSA and glucose metabolism has been described. Some endocrine and metabolic conditions (obesity, acromegaly, hypothyroidism, polycystic ovary disease, etc.) can be associated with OSA that may be improved by treatment of underlying endocrine disorders like hypothyroidism and acromegaly, where OSA is mainly related to upper airways narrowing due to reversible thickening of the pharyngeal walls. In other cases proper treatment of OSA has a beneficial effect on different endocrine disturbances. Central obesity is an important risk factor both in diabetes and sleep apnea, and recent evidence supports the direct association between them. There may be a positive feed back circle between the two disorders : sleep problems may affect endocrine function and metabolic conditions, while metabolic abnormalities potentially interfere with sleep regulation

New records of longhorn beetles (Coleoptera: Cerambycidae) in Bulgaria

During the period 1969-2019, longhorn beetles (Coleoptera: Cerambycidae) were studied in Bulgaria. In different regions of the country, 144 cerambycid taxa from six subfamilies were established: Prioninae (five species), Lepturinae (37 species and subspecies), Necydalinae (one species), Spondylidinae (nine species and subspecies), Cerambycinae (46 species and subspecies) and Lamiinae (46 species and subspecies). New localities of 14 rare cerambycid taxa were established (Pedostrangalia revestita, Alocerus moesiacus, Anisarthron barbipes, Icosium tomentosum atticum, Paraclytus sexguttatus, Aegomorphus krueperi, Agapanthia frivaldszkyi, Deroplia genei genei, Dorcadion equestre transsilvanicum, Phytoecia albovittigera, Phytoecia praetextata praetextata, Pogonocherus hispidus, Niphona picticornis and Saperda perforata). New longhorn beetles were also found in the West Balkan Range, the Eastern and Western Rhodopes, Maleshevska Planina Mt. and North-eastern Bulgaria. These new records enlarged the knowledge about the regional distribution of longhorn beetles in Bulgaria

[Reviews] Endocrine aspects of obstructive sleep apnea

[Abstract] Obstructive sleep apnea (OSA) is a common clinical condition that has variety of adverse effects on human health. Studies suggest that OSA increases the cardiovascular risk, and a link between OSA and glucose metabolism has been described. Some endocrine and metabolic conditions (obesity, acromegaly, hypothyroidism, polycystic ovary disease, etc.) can be associated with OSA that may be improved by treatment of underlying endocrine disorders like hypothyroidism and acromegaly, where OSA is mainly related to upper airways narrowing due to reversible thickening of the pharyngeal walls. In other cases proper treatment of OSA has a beneficial effect on different endocrine disturbances. Central obesity is an important risk factor both in diabetes and sleep apnea, and recent evidence supports the direct association between them. There may be a positive feed back circle between the two disorders : sleep problems may affect endocrine function and metabolic conditions, while metabolic abnormalities potentially interfere with sleep regulation

Clinical characteristics, treatment patterns, and socio-economic burden of COPD in Bulgaria

Background: While the impact of COPD in Western-Europe is known, data from Eastern-Europe is scarce. This study aimed to evaluate clinical characteristics, treatment patterns, and the socio-economic burden of COPD in Eastern-Europe, taking Bulgaria as a reference case. Methods: A representative sample of Bulgarian patients with COPD was randomly chosen by pulmonologists, based on the following inclusion criteria: COPD diagnosis with at least 1 year of living with COPD, >= 40 years of age, and use of COPD medication. Patient characteristics, treatment, quality-of-life, healthcare resource use, and costs were systematically assessed. Results: A total of 426 COPD patients were enrolled. Approximately 69% were male, 40% had occupational risk factors, 45% had severe and 11% had very severe COPD. Mean CAT scores were 13.80 (GOLD A), 21.80 (GOLD B), 17.35 (GOLD C), and 26.70 (GOLD D). Annual per-patient costs of healthcare utilization were Euro579. Yearly pharmacotherapy costs were Euro693. Indirect costs (reduced and lost work productivity) outnumbered direct costs three times. Conclusions: Bulgaria has relatively high percentages of (very) severe COPD patients, resulting in considerable socio-economic burden. High smoking rates, occupational risk factors, air pollution, and a differential health system may be related to this finding. Eastern-European COPD strategies should focus on prevention, risk-factor awareness, and early detection