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匹配条件: “Horia V. Bogdan” ,找到相关结果约131798条。
Lissotriton vulgaris paedomorphs in south-western Romania: a consequence of a human modified habitat?
Severus D. Covaciu-Marcov,Istvan Sas,Alfred ?. Cicort-Lucaciu,Horia V. Bogdan
Acta Herpetologica , 2011,
Abstract: A Lissotriton vulgaris paedomorph population was identified for the first time ever in south-western Romania. The newts inhabiting a permanent but artificial habitat, surrounded by agricultural fields.
Implication upon Herpetofauna of a Road and its Reconstruction in Carei Plain Natural Protected Area (Romania)
Alfred-S. Cicort-Lucaciu,Severus-D. Covaciu-Marcov,Horia V. Bogdan,Istvan Sas
Ecologia Balkanica , 2012,
Abstract: In autumn 2011 we monitored a 5 km long road, paved with cobblestone, situated in Carei Plain Natural Protected Area, a road that is due to be modernized and continued across the border into Hungary. Dead bodies from eight different animal groups were observed on the road, amphibians presenting the greatest amount. The most frequent were the Triturus dobrogicus corps, a species with conservation importance. The amphibians were affected in the areas where the road is neighboring the wetlands, while on the opposite pole sits the area with acacia plantations. The high number of mortalities recorded on the road, despite the low traffic speed, is alarming. It is likely that the modernization of the road that will surely increase its traffic and the speed of the vehicles, will make the situation even worse. However, the rebuilding could contribute to the reduction in the impact on amphibians, if certain measures are considered while planning the action. Thus, in the areas near the wetlands, there should be undercrossings, fences and speed limits. In this way, the modernization would at least represent an experiment regarding the diminution of the road’s impact on amphibians.
Ungureanu Mihai Dragos,Stoian Florin Bogdan,Ionescu George Horia,Vilag Ruxandra Dana
Annals of the University of Oradea : Economic Science , 2009,
Abstract: The convergence is an essential objective of the integration process of Romania in the European Union. Minimizing gaps in the level of development that arise between Romania and the average European Union can not be achieved solely through the use of mar
Lissotriton vulgaris paedomorphs in south-western Romania: a consequence of a human modified habitat ?
Severus-Daniel Covaciu-Marcov,Istvan Sas,Alfred-Stefan Cicort-Lucaciu,Horia-Vlad Bogdan
Acta Herpetologica , 2011,
Abstract: A Lissotriton vulgaris paedomorph population was identified for the first time ever in south-western Romania. The occurrence of this paedomorphosis is explained by the particularities of the area, the newts inhabiting a permanent but artificial habitat, surrounded by agricultural fields. Thus, the presence of an acceptable aquatic habitat together with the absence of a suitable terrestrial one triggered the occurrence of paedomorphosis.
New cases of winter-active amphibians in the thermal waters of Banat, Romania
Bogdan Horia-Vlad,Covaciu-Marcov Severus-Daniel,Antal Cornel,Cicort-Lucaciu Alfred-?tefan
Archives of Biological Sciences , 2011, DOI: 10.2298/abs1104219b
Abstract: In the winter of 2010/2011 we identified 6 new thermal habitats, with winter-active amphibian populations in the Banat region of south-western Romania. The diversity of the amphibian species was small, only 2 species were observed: Bombina bombina and Pelophylax ridibundus. In waters with high flow and temperature, the number of winteractive frogs reached several hundred. All the new thermal habitats are artificial, being subjected to a powerful anthropogenic pressure.
Representations of analytic functions as infinite products and their application to numerical computations
Marcin Mazur,Bogdan V. Petrenko
Mathematics , 2012,
Abstract: Let $D$ be an open disk of radius $\le 1$ in $\mathbb C$, and let $(\epsilon_n)$ be a sequence of $\pm 1$. We prove that for every analytic function $f: D \to \mathbb C$ without zeros in $D$, there exists a unique sequence $(\alpha_n)$ of complex numbers such that $f(z) = f(0)\prod_{n=1}^{\infty} (1+\epsilon_nz^n)^{\alpha_n}$ for every $z \in D$. From this representation we obtain a numerical method for calculating products of the form $\prod_{p \text{prime}} f(1/p)$ provided $f(0)=1$ and $f'(0) = 0$; our method generalizes a well known method of Pieter Moree. We illustrate this method on a constant of Ramanujan $\pi^{-1/2}\prod_{p \text{prime}} \sqrt{p^2-p}\ln(p/(p-1))$. From the properties of the exponents $\alpha_n$, we obtain a proof of the following congruences, which have been the subject of several recent publications motivated by some questions of Arnold: for every $n \times n$ integral matrix $A$, every prime number $p$, and every positive integer $k$ we have $\text{tr} A^{p^k} \equiv \text{tr} A^{p^{k-1}} (\text{mod}\,{p^k})$.
On the conjectures of Atiyah and Sutcliffe
Marcin Mazur,Bogdan V. Petrenko
Mathematics , 2011,
Abstract: Motivated by certain questions in physics, Atiyah defined a determinant function which to any set of $n$ distinct points $x_1,..., x_n$ in $\mathbb R^3$ assigns a complex number $D(x_1,..., x_n)$. In a joint work, he and Sutcliffe stated three intriguing conjectures about this determinant. They provided compelling numerical evidence for the conjectures and an interesting physical interpretation of the determinant. The first conjecture asserts that the determinant never vanishes, the second states that its absolute value is at least one, and the third says that $|D(x_1,..., x_n)|^{n-2}\geq \prod_{i=1}^n |D(x_1,..., x_{i-1},x_{i+1},..., x_n)|$. Despite their simple formulation, these conjectures appear to be notoriously difficult. Let $D_n$ denote the Atiyah determinant evaluated at the vertices of a regular $n-$gon. We prove that $\lim_{n\to \infty} \frac{\ln D_n}{n^2}= \frac{7\zeta(3)}{2\pi^2}-\frac{\ln 2}{2}=0.07970479...$ and establish the second conjecture in this case. Furthermore, we prove the second conjecture for vertices of a convex quadrilateral and the third conjecture for vertices of an inscribed quadrilateral.
Reggeized quark -- Reggeized quark -- gluon effective vertex
Bogdan, A. V.;Grabovsky, A. V.
High Energy Physics - Phenomenology , 2007, DOI: 10.1016/j.nuclphysb.2007.03.017
Abstract: This paper is devoted to the calculation of the Reggeized quark-Reggeized quark-gluon effective vertex in perturbative QCD in the next-to-leading order. The case of QCD with massless quarks is considered and the correction is obtained in the D->4 limit. This vertex appears in the quark Reggeization theory, which next-to-leading order extension is now under construction.
Aerodynamics of Bladed Machinery (Aerodinamica masinilor cu palete) Corneliu BERBENTE, Marius BREBENEL “Editura Academiei Romane”, Bucharest, Romania, 2010, Book review
INCAS Bulletin , 2011, DOI: doi: 10.13111/2066-8201.2011.3.2.13
Professor Ion Stroescu and the boundary layer: a precursor of the flow control
INCAS Bulletin , 2011, DOI: 10.13111/2066-8201.2011.3.s4

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