Showing papers by "Jagiellonian University published in 1991"

The genetic structure of the hybrid zone between the fire-bellied toads bombina bombina and b. variegata: comparisons between transects and between loci.

Abstract: We compare the pattern of morphological and electrophoretic variation in the hybrid zone between Bombina bombina and B. variegata across two transects: one near Cracow and one 200 km away, near Przemyśl in southeastern Poland. Morphological variation across the Przemyśl transect had been surveyed more than 50 years ago; though we found a significant shift at one site, there is no evidence for gross movement over this period. Morphological and electrophoretic changes coincide, and the average shape of the clines is the same across both transects. At the center, most of the change in frequency of six diagnostic allozymes occurs within w = 6.05 km (2-unit support limits 5.56-6.54 km). These steep gradients are generated not by selection on the allozymes themselves, but by associations with other loci: though these markers are unlinked, they are in strong linkage disequilibrium with each other [R = D/√pquv = 0.22 (0.15-0.29) at the center]. Disequilibria are broken up as alleles diffuse away from the zone and flow into the new genetic background. The net barrier to the flow of genes from bombina into variegata, which is generated by these disequilibria, is B = 51 (22-81) km. The fitness of hybrids must be substantially reduced to produce such a barrier [WH /WP = 0.58 (0.54-0.68)], and this selection must be spread over many loci [N = 55 (26-88)]. Alleles introgress significantly less far than would be expected from the age of the zone and the estimated dispersal rate [σ = 0.99 (0.82-1.14) km gen.1/2 ]: this implies selection of se = 0.37 (0.15-0.58)% on the enzymes themselves. There is weak but significant linkage disequilibrium well away from the center of the zone; this, together with the presence of parental and F1 genotypes, suggests some long-range migration. However, such migration is not likely to cause significant introgression.

Stochastic partial differential equations and turbulence

Abstract: Stochastic partial differential equations are proposed in order to model some turbulence phenomena. A particular case (the stochastic Burgers equations) is studied. Global existence of solutions is proved. Their regularity is also studied in detail. It is shown that the solutions cannot possess too high regularity.

An increased level of sperm abnormalities in mice with a partial deletion of the Y chromosome.

Abstract: Two congenic lines of mice, one with a partial deletion of the Y chromosome, differ in the percentage of spermatozoa with abnormal heads: B10.BR/SgSn males give 22·6%; and B10.BR-Ydel/Ms males give 64·2%; abnormal sperm. The F1s resulting from crosses of B10.BR/SgSn males with females of five common inbred strains exhibited significantly lower levels of abnormal sperm than the parental strains, as opposed to F1 hybrids sired by B10.BR-Ydel/Ms mutant males, where very high levels of abnormal spermatozoa were found. About 30%; of abnormal spermatozoa, produced by males with deletion on the Y chromosome, were characterized by a flat acrosomal cap. This class of abnormality was never observed in non-mutant males, suggesting a mutant-specific defect. These results demonstrate the important role of the Y chromosome in spermatogenesis.

Electronic structure of the ordered phases of Pt-Fe alloys.

Abstract: The electronic structure of several ordered phases of the Pt-Fe system is studied using the self-consistent linear muffin-tin-orbital method. The phases studied include nonmagnetic and ferromagnetic ${\mathrm{PtFe}}_{3}$, ferromagnetic ${\mathrm{Pt}}_{2}$${\mathrm{Fe}}_{2}$, antiferromagnetic and ferromagnetic ${\mathrm{Pt}}_{3}$Fe, and ferromagnetic ${\mathrm{Pt}}_{5}$${\mathrm{Fe}}_{3}$. The electronic structure, the densities of states, and the ground-state properties, such as equilibrium lattice constants, bulk moduli, local and average magnetic moments, and the state equations are calculated. The calculated parameters compare favorably with existing experimental data. The cohesive properties, chemical bonding, and the moment-stabilizing mechanism are discussed. A variation of all these aspects with alloy composition illustrates a continuous transition from itinerant to local-moment magnetism. An interplay of the covalent bonding, scalar relativistic effects, electronegativity, and the charge transfer is shown to be responsible for this transition. Homogeneity of the magnetic state of ${\mathrm{PtFe}}_{3}$ Invar is explained. On the basis of the calculated elastic properties and recently reported critical pressures at which the magnetic moment of ${\mathrm{PtFe}}_{3}$ collapses, the total energy difference between the ferromagnetic and nonmagnetic phase is estimated.

Monte Carlo simulations of energetic particle transport in weakly inhomogeneous magnetic fields – I. Particle acceleration in relativistic shock waves with oblique magnetic fields

Abstract: An extended form of the Kirk J. G. and Schneider P. (1988, Astron. Astrophys., 201) method for simulation of energetic particle transport in weakly disturbed magnetic fields is presented. It is based on the mean field + perturbations decomposition of magnetic field, i.e. a particle is considered to propagate in the mean field along its undisturbed adiabatic trajectory, while the magnetic field inhomogeneities are allowed for by perturbing the trajectory parameters in finite time-steps. For the application of the method, a simulation of a particle shock acceleration in relativistic shock waves with oblique magnetic fields is realised.

Influence of partial deletion of the Y chromosome on mouse sperm phenotype.

Abstract: Two congenic strains of mice (control, B10.BR/SgSn; mutant, B10.BR-Ydel/Ms with partial deletion of the Y chromosome) were examined. In control males, 22.6% of spermatozoa had abnormal heads; in mutant males, there were 64.2%, the most common being heads with flat acrosomes. Sodium dodecyl sulphate polyacrylamide gel electrophoresis of mature sperm proteins, followed by acrosin assay and acrosome silver staining, revealed a reduced concentration of acrosin in acrosomal caps in 35.8% of the spermatozoa in mutant males. Electron microscope analysis showed that some of the round, early spermatids in the mutants had normally formed acrosomal caps but lacked the proacrosomal granule and had no, or only scarce, acrosomal material. These observations indicate that formation of the acrosomal cap is controlled separately from the synthesis of the acrosomal material and suggest that some factors linked on the Y chromosome are involved in the control of acrosome development.

Chitin and its derivative as supports for immobilization of enzymes

Abstract: The ideal enzyme support should show high affinity to proteins, availability of reactive groups for direct reactions with proteins or for chemical modifications, easiness of preparing in different physical forms, nontoxicity and physiological compatability if required (food industry, biomedicine), as well as low cost. Chitin and its derivatives fullfil most of these requirements. The paper reviews enzymes immobilized on chitin and its derivatives along with techniques applied for their immobilization.

Theory of dressed-state lasers. I. Effective Hamiltonians and stability properties

Abstract: We present a detailed theory of dressed-state lasers, i.e., the lasers that operate due to the gain on an inverted transition between dressed states of a coupled atom-field system. We derive effective Hamiltonians that describe such lasers for the case of one- and two-photon resonances. We argue that, due to the presence of nearly resonant intermediate states, the use of gain media consisting of strongly driven two-level atoms provides an unorthodox yet promising means for achieving cw optical two-photon laser oscillation. We disscuss the stability properties of radiation generated by such media.

Reproductive biology of the fire-bellied toads, Bombina bombina and B. variegata (Anura: Discoglossidae): egg size, clutch size and larval period length differences

Abstract: Clutch size, egg size, larval size and duration of larval period were estimated for samples of Bombina bombina and B. variegata from several populations. Bombina variegata lays fewer eggs per batch (mean 17.4) than B. bombina (mean 32.5). The volume of B. variegata eggs is 2.4 times greater and the dry weight 2.3 times greater than that of B. bombina. As a consequence, the volume of B. variegata hatchlings and their dry weight are respectively 1.9 times and 2.5 times greater than that of B. bombina. Analysis of variance showed that variation of egg size in B. variegata is significantly greater than in B. bombina. When reared under laboratory conditions freshly metamorphosed individuals of both species showed no difference in body size or weight. Although growth rates are equal, tadpoles of B. variegata reached metamorphosis 14 days earlier than B. bombina tadpoles because of differences in size of hatchlings. Differences in reproductive parameters found for the two European Bombina species can be interpreted as adaptations to contrasting environments in which they breed.

Photoinduced electron transfer reactions of rose bengal and selected electron donors

Abstract: The photoinduced electron transfer reactions of the triplet state of rose bengal (RB) and several electron donors were investigated by the complementary techniques of steady state and time-resolved electron paramagnetic resonance (EPR) and laser flash photolysis (LFP). The yield of radicals varied with the light fluence rate, RB concentration and, in particular, the electron donor used. Thus for L-dopa (dopa, dihydroxyphenylalanine) only 10% of RB anion radical (RB −) was produced, with double the yield observed with NADH (NAD, nicotinamide adenine dinucleotide) as quencher and more than three times the yield observed with ascorbate as quencher. Quenching of the RB triplet was both reactive and physical with total quenching rate constants of 4 × 10 8 mol −1 dm 3 s −1 and 8.5 × 10 8 mol −1 dm 3 s −1 for ascorbate and NADH respectively. The rate constant for the photoinduced electron transfer from ascorbate to RB triplet was 1.4 × 10 8 mol −1 dm 3 s −1 as determined by Fourier transform EPR (FT EPR). FT EPR spectra were spin polarized in emission at early times indicating a radical pair mechanism for the chemically induced dynamic electron polarization. Subsequent to the initial electron transfer production of radicals, a complex series of reactions was observed, which were dominated by processes such as recombination, disproportionation and secondary (bleaching) reactions. It was observed that back electron transfer reactions could be prevented by mild oxidants such as ferric compounds and duroquinone, which were efficiently reduced by RB −.

Activation of reproduction in nulliparous and primiparous voles is blocked by vomeronasal organ removal.

Abstract: Chemical cues from male voles activate reproduction in female prairie voles (Microtus ochrogaster). Twelve hours of contact with a male, followed by exposure to his soiled bedding for 2 days, is sufficient to initiate follicular maturation and induce uterine hypertrophy. Our recent work indicates that the chemosensory vomeronasal organ (VNO) can mediate this response. Here, we examined whether other sensory systems can acquire the ability to activate female reproduction as a result of learning or experience

Effects of interleukin-6 and leukemia inhibitory factor on the acute phase response and DNA synthesis in cultured rat hepatocytes.

Abstract: Human recombinant interleukin-6 (IL-6) and human recombinant leukemia inhibitory factor (LIF) similarly stimulate synthesis of typical acute-phase proteins in the primary rat hepatocyte cultures. LIF is, however, less effective in increasing uptake of alpha-aminoisobutyric acid than IL-6. Antiserum to human IL-6 abolishes induced protein synthesis and amino acid uptake elicited by hrIL-6 but has no effect on the acute-phase response of rat liver cells stimulated by LIF. Both IL-6 and LIF inhibit basal and epidermal growth factor-induced DNA synthesis in rat hepatocytes.

Injective endomorphisms of algebraic and analytic sets

Abstract: We prove that every injective endomorphism of an affine algebraic variety over an algebraically closed field of characteristic zero is an automorphism. We also construct an analytic curve in C and its holomorphic bijection which is not a biholomorphism. Introduction. The Zariski Main Theorem (see e.g. [4]) asserts that every injective morphism of normal algebraic varieties over an algebraically closed field of characteristic zero is an automorphism onto its open image. For arbitrary complex algebraic varieties regularity of the inverse of a regular biholomorphic bijection is ensured by the Serre Theorem [7, 9]. The simple example C 3 t → (t, t) ∈ {x − y = 0} shows that in general, bijective morphisms are not isomorphisms. From the example {xy−1 = 0} 3 (u, v)→ (u, 0) ∈ {y = 0} we see that an injective morphism of non-singular algebraic sets may not be surjective. Grothendieck proved in [5, Prop. 17.9.6] a counterpart of the Zariski Main Theorem for the category of S-preschemes, where S is a fixed prescheme. His theorem says that every injective S-endomorphism of an Sprescheme of finite presentation is an automorphism. Note that his theorem is unapplicable to endomorphisms of algebraic sets. Our main result gives a geometric counterpart of the Grothendieck result; Theorem 2.2 says that every injective endomorphism of an affine algebraic variety over an algebraically closed field k of characteristic zero is an automorphism. This generalizes the well-known result of Bia lynicki-Birula and Rosenlicht [2] saying that every injective polynomial transformation of k is a polynomial automorphism. Note that surjectivity of an injective endomorphism of an affine algebraic variety was earlier proved by Ax [1]. In the proof Ax applied the so-called 1991 Mathematics Subject Classification: Primary: 14A10, 32C15; Secondary 14E99, 32C25. 30 S. Cynk and K. Rusek “transfer principle” and the metamathematical notion of an “elementary formula”. A topological proof of Ax’s Theorem was given by Borel in his unpublished paper [3]. One can also consider Theorem 2.2 as an analogue of the Clements– Osgood Theorem on analyticity of the inverse of a holomorphic bijection of a complex manifold. In Section 3 we show that there is no counterpart of Theorem 2.2 for the category of analytic sets. In order to obtain a suitable counterexample we construct an irreducible one-dimensional complex analytic space and its holomorphic but not biholomorphic bijection and next we prove that this analytic space is biholomorphic with an analytic curve in C. 1. Dominating regular mappings with finite fibres. Let F : V → W be a regular dominating mapping of irreducible affine algebraic varieties over k, i.e. F (V ) = W . Then the induced homomorphism F∗ : k[W ]→ k[V ] of rings of regular functions is injective, so it has a unique extension to a monomorphism of fields of rational functions, also denoted by F∗ : k(W )→ k(V ). If we assume additionally that dimV = dimW then the field k(V ) is a finite extension of the field F∗(k(W )); we put d(F ) = [k(V ) : F∗(k(W ))]. It is well known that d(F ) is equal to the number of points in the generic fibre of F (see e.g. [4]). In some cases we have more precise information about the number d(F ): Theorem 1.1. Let V and W be normal affine varieties and dimV = dimW . If F : V → W is a regular dominating mapping with finite fibres then d(F ) = max{#F−1(y) : y ∈W}. For the proof we need the following Lemma 1.2. Let V and W be irreducible affine algebraic varieties such that dimV = dimW and V is normal. Assume that F : V → W is a regular dominating mapping with finite fibres. Then, for every y ∈ W with F−1(y) = {x1, . . . , xm} ⊂ V , there exists a function f ∈ k[V ] which is integral over F∗(k[W ]) and f(xi) 6= f(xj) for i 6= j. P r o o f. By [4, Corollary 1, p. 136] we can find a normal affine algebraic variety W ′, a regular injective mapping F ′ : V → W ′ and a regular finite mapping G : W ′ →W such that F = G ◦ F ′. Then the points {F (xj) : j = 1, . . . ,m} ⊂ W ′ are pairwise different, so there exists g ∈ k[W ′] such that g(F (xi)) 6= g(F (xj)) for i 6= j. Since G is finite, the ring k[W ′] is integral over the ring G∗ (k[W ]). Therefore f = g ◦ F ′ = F ′ ∗(g) has all desired properties. P r o o f o f T h e o r e m 1.1. Take a y ∈ W and the function f ∈ k[V ] from Lemma 1.2 which is integral over the ring F∗(k[W ]) and separates the Injective endomorphisms 31 points in the fibre F−1(y) = {x1, . . . , xm} ⊂ V . In the extension of integral rings F∗(k[W ]) ⊂ k[V ] the ring F∗(k[W ]) is normal. One can easily verify that f ∈ k[V ] is algebraic over the field F∗(k(W )) and the coefficients of its minimal equation of degree d over F∗(k(W )) lie in F∗(k[W ]). Since all functions from F∗(k[W ]) are constant on the set F−1(y) whose elements are separated by f , we have m ≤ d ≤ d(F ). Hence d(F ) = max{#F−1(y) : y ∈W}. 2. Bijectivity implies biregularity. Assume that all varieties occurring in this section are defined over a field k (algebraically closed of characteristic zero). Lemma 2.1. Let V be an affine algebraic variety and let V = V1∪ . . .∪Vs be its decomposition into irreducible components. Denote by πi : V̂i → Vi a normalization of Vi for i = 1, . . . , s. Then MV = {f : V → k : f ◦ πi ∈ k[V̂i] for i = 1, . . . , s} is a noetherian k[V ]-module (under the standard operations). P r o o f. Since k[V̂i] is a noetherian k[Vi]-module, it is also a noetherian k[V ]-module for every i = 1, . . . , s (under the multiplication rf = (r ◦ πi)f for r ∈ k[V ], f ∈ k[V̂i].) The mapping MV 3 f → (f ◦ π1, . . . , f ◦ πs) ∈ s ⊕

Transect for aerobiological studies from Antarctica to Poland

Abstract: While returning from the 13th Polish Scientific Expedition to Antarctica, one of the authors (M.O.) collected airborne biological samples along the transect from the South Shetland Islands to Gdynia on the Baltic Seacoast of Poland. The journey aboard the Polish ship ORP “Heweliusz”, lasted from 4 March until 13 April 1990. During this period, two samples a day, exposed 12 h each, were collected in Petri dishes. The authors made preliminary identifications of plant and animal fragments in the samples. The most important finding was the presence of propagules of lichens (fragments of thallus, isidia soredia) in all samples. The relatively small number of pollen grains in samples could be accounted for by the season of collection when few pollen grains are airborne.

Manifestation of wave chaos in pseudointegrable microwave resonators.

Abstract: We analyze the distribution of eigenfrequencies of microwave resonators which correspond to pseudointegrable billiards. The statistical properties of the measured spectra are explained by means of a model of additive random matrices.

1:1 Molybdenum(VI) citric acid complexes

Abstract: The complexes obtained by crystallisation from an aqueous solution of molybdate and citric acid (H4cit) at pH 4–8 have Mo:cit ratio 1∶1. The new complexes have been characterised by a variety of methods in the solid state and in solution. On this basis two dimeric species, [(MoO2)2O(citH)2]4− and [(MoO2)2O(cit)2]6−, and a monomeric species [MoO3(cit)OH2]4− are proposed.

On Dielectric Relaxation in Liquid Crystals

Abstract: A general expansion of the orientational distribution function in terms of the Wigner matrix is employed in order to calculate dipole moment correlation functions in liquid crystals. It is shown that the qualitative interpretation of dielectric relaxation spectra of liquid crystals is possible without explicit characterization of the molecular motions involved. Thus, a wide range of stochastic motions can be considered within the framework of the model. A fundamental influence of the orientational order of molecules in the liquid-crystalline state on the qualitative form of dielectric spectra is emphasized.

Nuclear microscopy of biological specimens

Abstract: Recent developments in technology have enabled the scanning proton microprobe to scan at submicron spatial resolution on a routine basis. The use of the powerful combination of techniques PIXE (proton induced X-ray emission), nuclear (or Rutherford) backscattering (RBS), and secondary electron detection operating at this resolution will open up new areas in many scientific disciplines. This paper describes some of the work carried out in the biological sciences over the last year, using the Oxford SPM facility. Collaborations with biological scientists have drawn attention to the wealth of information that can be derived when these techniques are applied to micro-organisms, cells and plant tissue. Briefly described here are investigations into the uptake of heavy metals by the alga Pandorina morum, the structure of the diatom Stephanopyxis turris, the presence of various types of crystal structures within the cells of Spirogyra, the heavy metal uptake of a mycorrhizal fungus present in the bracken (Pteridium aquilinum) root, the role of sphagnum moss in the absorption of inorganic elements, the measurement of heavy metals in environmentally-adapted cells of the yeast Saccharomyces cerevisiae, and the elemental distribution in the growing tip of a spore from the plant Equisetum arvense, with special emphasis placed on the visual interpretation of the elemental and secondary-electron maps provided by the nuclear microscopical techniques.

Normal (decoupled) representation of electronegativity equalization equations in a molecule

Abstract: The decoupled (normal) representation of the electronegativity (chemical potential) equalization equations, in which the hardness tensor {ηij}={∂μi/∂Nj} becomes diagonal, is examined in the atoms-in-a-molecule (AIM) approximation; μi=∂E/∂Ni is the chemical potential of the i-th AIM, Ni is its electron population, and E is the system energy. All relevant chemical potential, hardness, softness, and Fukui function quantities corresponding to the normal electron redistribution channels, Qy, are discussed and expressed in terms of the canonical AIM parameters. The normal chemical potentials, μγ=∂E/∂Qγ, provide a natural classification of the normal modes into three groups: (a) acceptor normal modes (μa 0, negative mode Fukui function, hardness, and softness), and (c) polarization normal modes (μp=0, zero mode Fukui function, hardness, and softness). The implications of the normal mode analysis for the theory of chemical reactivity are briefly summarized.