Efikasnost ulja karanfilića kao anestetika za cverglana (Ictalurus punctatus raf.)

Cilj rada je bio da se odredi optimalna koncetracija ulja karanfilića potrebna za anesteziju i oporavak dvogodišnjeg cverglana. Eksperimenti su izvedeni u laboratorijskim uslovima. Ispitivano je dejstvo tri koncentracije: 0.02 ml.l-1, 0.04 ml.l-1 i 0.06 ml.l-1. Tokom procesa anesteziranja je praćeno i analizirano ponašanje riba. Koncetracija od 0.02 ml.l-1 je imala sedativan efekat na ribe i dovela do poremećaja ravnoteže. Pri koncentraciji od 0.04 ml.l-1 90% riba je bilo potpuno imobilisano u roku od 3.17 to 6 min. Pri najvišoj koncetraciji, od 0.06 ml.l-1, sve ribe su bile potpuno imobilisane u roku od 2 do 4 minuta

Apolarity, Hessian and Macaulay polynomials

A result by Macaulay states that an Artinian graded Gorenstein ring R of socle dimension one and socle degree b can be realized as the apolar ring of a homogeneous polynomial f of degree b. If R is the Jacobian ring of a smooth hypersurface g=0, then b is just equal to the degree of the Hessian polynomial of g. In this paper we investigate the relationship between f and the Hessian polynomial of g.Comment: 12 pages. Improved exposition, minor correction

Frames of reference in spaces with affine connections and metrics

A generalized definition of a frame of reference in spaces with affine connections and metrics is proposed based on the set of the following differential-geometric objects: (a) a non-null (non-isotropic) vector field, (b) the orthogonal to the vector field sub space, (c) an affine connection and the related to it covariant differential operator determining a transport along the given non-null vector filed. On the grounds of this definition other definitions related to the notions of accelerated, inertial, proper accelerated and proper inertial frames of reference are introduced and applied to some mathematical models for the space-time. The auto-parallel equation is obtained as an Euler-Lagrange's equation. Einstein's theory of gravitation appears as a theory for determination of a special frame of reference (with the gravitational force as inertial force) by means of the metrics and the characteristics of a material distribution. PACS numbers: 0490, 0450, 1210G, 0240VComment: 17 pages, LaTeX 2

Raman and Infrared-Active Phonons in Hexagonal HoMnO3_3 Single Crystals: Magnetic Ordering Effects

Polarized Raman scattering and infrared reflection spectra of hexagonal HoMnO$_3$ single crystals in the temperature range 10-300 K are reported. Group-theoretical analysis is performed and scattering selection rules for the second order scattering processes are presented. Based on the results of lattice dynamics calculations, performed within the shell model, the observed lines in the spectra are assigned to definite lattice vibrations. The magnetic ordering of Mn ions, which occurs below T$_N$=76 K, is shown to effect both Raman- and infrared-active phonons, which modulate Mn-O-Mn bonds and, consequently, Mn exchange interaction.Comment: 8 pages, 6 figure