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Search Results: 1 - 10 of 27 matches for " Rodeva Velichka "
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In vitro answer of Bulgarian pepper (Capsicum annuum L.)
Rodeva Velichka,Grozeva Stanislava,Todorova Velichka
Genetika , 2006, DOI: 10.2298/gensr0602129r
Abstract: Callusogenesis and regeneration ability of cotyledon and hypocotyl explants from three Bulgarian pepper varieties in MS basal medium supplemented with l-3mg/l BAP. l.0mg/1 IAA and 0.5mg/l GA3 was studied. In the different variants of culture medium was registered high level of callusogenesis and organogenesis in both type of explants from the all varieties. The highest percentage of plant-regenerants is established in cotyledon explants (from 3.3 to 18.3) in variant 3 of the culture medium containing 3mg/l BA. In the process of micropropagation by stem explants of the same studied pepper varieties the addition of the vitamins C. B12. Casein hydrolysate and Ferulic acid had a stimulation effect on the plant growth in height and rooting. In result of anther cultivation from three pepper varieties and four breeding lines the highest percentage of embryo structure formation was registered in varieties Albena and Strjama (12.0 and 13.8 respectively). The Bulgarian peppers are recalcitrant and their in vitro answer is different depending from the explants type, genotype and the culture media composition.
L’Ouest face à l’Est : de l’idéal à la désillusion. Viktor Paskov, Milan Kundera, Philip Roth
Velichka Ivanova
Trans : Revue de Littérature Générale et Comparée , 2008,
Abstract: L’étude analyse d’un point de vue comparatiste l’opposition entre l’Est et l’Ouest telle qu’elle appara t dans le roman contemporain. Elle interroge trois espaces géographiques et littéraires : L’Europe de l’Est, l’Europe Centrale, et l’Occident. L’analyse associe dans ce but le Bulgare Viktor Paskov, le Tchèque Milan Kundera et l’Américain Philip Roth. Elle retient les romans Allemagne, conte cruel (1991) du premier, L’Insoutenable légèreté de l’être (1984) du deuxième et J’ai épousé un communiste (1998) du troisième. The study analyzes, in a comparative approach, the opposition between East and West in the contemporary novel. It considers three geographical and literary areas: Eastern Europe, Central Europe, and the West. For this purpose, the article associates the Bulgarian Viktor Paskov, the Czech Milan Kundera and the American Philip Roth. It includes Germany, a Dirty Tale (1991) by Paskov, The Unbearable Lightness of Being (1984) by Kundera, and I Married a Communist (1998) by Roth. El trabajo analiza desde un punto de vista comparatista, la oposición entre el Este y el Oeste tal como aparece en la novela contemporánea. Interroga así tres espacios geográficos y literarios: Europa del Este, Europa Central y Occidente. El artículo asocia con este fin al búlgaro Viktor Paskov, al checo Milan Kundera y al estadounidense Philip Roth, con las obras Allemagne, conte cruel (1991), L’Insoutenable légèreté de l’être (1984) J’ai épousé un communiste (1998) respectivamente de cada autor.
General Rotational Surfaces in $\R^4$ with Meridians Lying in Two-Dimensional Planes
Velichka Milousheva
Mathematics , 2010,
Abstract: We apply the invariant theory of surfaces in the four-dimensional Euclidean space to the class of general rotational surfaces with meridians lying in two-dimensional planes. We find all minimal super-conformal surfaces of this class.
Marginally trapped surfaces with pointwise 1-type Gauss map in Minkowski 4-space
Velichka Milousheva
Mathematics , 2014,
Abstract: A marginally trapped surface in the four-dimensional Minkowski space is a spacelike surface whose mean curvature vector is lightlike at each point. In the present paper we find all marginally trapped surfaces with pointwise 1-type Gauss map. We prove that a marginally trapped surface is of pointwise 1-type Gauss map if and only if it has parallel mean curvature vector field.
David Gooblar. The Major Phases of Philip Roth.
Velichka D. Ivanova
European Journal of American Studies , 2012, DOI: 10.4000/ejas.9466
Abstract: In his 1984 discussion of the art of fiction, Philip Roth observes that, although he has always pursued his own line of work, his books have never been detached from his country’s history and culture or from his personal experience and reading. Indeed, Roth agues, “[t]here’s always something behind a book to which it has no seeming connection, something invisible to the reader which has helped to release the writer’s initial impulse” (“The Art of Fiction” 234). In response to this remark, Dav...
On the Theory of Surfaces in the Four-dimensional Euclidean Space
Georgi Ganchev,Velichka Milousheva
Mathematics , 2007,
Abstract: For a two-dimensional surface in the four-dimensional Euclidean space we introduce an invariant linear map of Weingarten type in the tangent space of the surface, which generates two invariants k and kappa. The condition k = kappa = 0 characterizes the surfaces consisting of flat points. The minimal surfaces are characterized by the equality kappa^2=k. The class of the surfaces with flat normal connection is characterized by the condition kappa = 0. For the surfaces of general type we obtain a geometrically determined orthonormal frame field at each point and derive Frenet-type derivative formulas. We apply our theory to the class of the rotational surfaces, which prove to be surfaces with flat normal connection, and describe the rotational surfaces with constant invariants.
An Invariant Theory of Spacelike Surfaces in the Four-dimensional Minkowski Space
Georgi Ganchev,Velichka Milousheva
Mathematics , 2010, DOI: 10.1007/s00009-010-0108-2
Abstract: We consider spacelike surfaces in the four-dimensional Minkowski space and introduce geometrically an invariant linear map of Weingarten-type in the tangent plane at any point of the surface under consideration. This allows us to introduce principal lines and an invariant moving frame field. Writing derivative formulas of Frenet-type for this frame field, we obtain eight invariant functions. We prove a fundamental theorem of Bonnet-type, stating that these eight invariants under some natural conditions determine the surface up to a motion. We show that the basic geometric classes of spacelike surfaces in the four-dimensional Minkowski space, determined by conditions on their invariants, can be interpreted in terms of the properties of the two geometric figures: the tangent indicatrix, and the normal curvature ellipse. We apply our theory to a class of spacelike general rotational surfaces.
Chen Rotational Surfaces of Hyperbolic or Elliptic Type in the Four-dimensional Minkowski Space
Georgi Ganchev,Velichka Milousheva
Mathematics , 2010,
Abstract: We study the class of spacelike surfaces in the four-dimensional Minkowski space whose mean curvature vector at any point is a non-zero spacelike vector or timelike vector. These surfaces are determined up to a motion by eight invariant functions satisfying some natural conditions. The subclass of Chen surfaces is characterized by the condition one of these invariants to be zero. In the present paper we describe all Chen spacelike rotational surfaces of hyperbolic or elliptic type.
Quasi-minimal Rotational Surfaces in Pseudo-Euclidean Four-dimensional Space
Georgi Ganchev,Velichka Milousheva
Mathematics , 2012, DOI: 10.2478/s11533-014-0430-1
Abstract: In the four-dimensional pseudo-Euclidean space with neutral metric there are three types of rotational surfaces with two-dimensional axis - rotational surfaces of elliptic, hyperbolic or parabolic type. A surface whose mean curvature vector field is lightlike is said to be quasi-minimal. In this paper we classify all quasi-minimal rotational surfaces of elliptic, hyperbolic and parabolic type, respectively.
General Rotational Surfaces in the Four-dimensional Minkowski Space
Georgi Ganchev,Velichka Milousheva
Mathematics , 2013, DOI: 10.3906/mat-1312-10
Abstract: General rotational surfaces as a source of examples of surfaces in the four-dimensional Euclidean space have been introduced by C. Moore. In this paper we consider the analogue of these surfaces in the Minkowski 4-space. On the base of our invariant theory of spacelike surfaces we study general rotational surfaces with special invariants. We describe analytically the flat general rotational surfaces and the general rotational surfaces with flat normal connection. We classify completely the minimal general rotational surfaces and the general rotational surfaces consisting of parabolic points.
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