46 research outputs found

    Advantage of Animal Models with Metabolic Flexibility for Space Research Beyond Low Earth Orbit

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    As the worlds space agencies and commercial entities continue to expand beyond Low Earth Orbit (LEO), novel approaches to carry out biomedical experiments with animals are required to address the challenge of adaptation to space flight and new planetary environments. The extended time and distance of space travel along with reduced involvement of Earth-based mission support increases the cumulative impact of the risks encountered in space. To respond to these challenges, it becomes increasingly important to develop the capability to manage an organisms self-regulatory control system, which would enable survival in extraterrestrial environments. To significantly reduce the risk to animals on future long duration space missions, we propose the use of metabolically flexible animal models as pathfinders, which are capable of tolerating the environmental extremes exhibited in spaceflight, including altered gravity, exposure to space radiation, chemically reactive planetary environments and temperature extremes.In this report we survey several of the pivotal metabolic flexibility studies and discuss the importance of utilizing animal models with metabolic flexibility with particular attention given to the ability to suppress the organism's metabolism in spaceflight experiments beyond LEO. The presented analysis demonstrates the adjuvant benefits of these factors to minimize damage caused by exposure to spaceflight and extreme planetary environments. Examples of microorganisms and animal models with dormancy capabilities suitable for space research are considered in the context of their survivability under hostile or deadly environments outside of Earth. Potential steps toward implementation of metabolic control technology in spaceflight architecture and its benefits for animal experiments and manned space exploration missions are discussed

    Deformed Harmonic Oscillators for Metal Clusters: Analytic Properties and Supershells

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    The analytic properties of Nilsson's Modified Oscillator (MO), which was first introduced in nuclear structure, and of the recently introduced, based on quantum algebraic techniques, 3-dimensional q-deformed harmonic oscillator (3-dim q-HO) with Uq(3) > SOq(3) symmetry, which is known to reproduce correctly in terms of only one parameter the magic numbers of alkali clusters up to 1500 (the expected limit of validity for theories based on the filling of electronic shells), are considered. Exact expressions for the total energy of closed shells are determined and compared among them. Furthermore, the systematics of the appearance of supershells in the spectra of the two oscillators is considered, showing that the 3-dim q-HO correctly predicts the first supershell closure in alkali clusters without use of any extra parameter.Comment: 25 pages LaTeX plus 21 postscript figure

    CraniologiCal CharaCteristiCs of wild boars from the region of sarnena sredna gora mountain, bulgaria

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    abstract Doychev, v., Е. Raychev and D. KostoV, 2012. craniological characteristics of wild boars from the region of sarnena sredna Gora Mountain, Bulgaria. Bulg. J. Agric. Sci., craniological analysis of 18 male wild boar skulls has been conducted at completed growth (fully-grown third molar tooth). 44 craniological measurements have been made characterizing both the basic skull shapes and proportions (length, height, width and profile line), and the shape and proportions of the various skull parts (facial and cerebral) and of the various bones (lacrimal, palatal, etc.). the values found have been compared to the ones obtained by other authors. Based on the values found a classification analysis has been made to establish the population appurtenance of wild boars inhabiting in the region of sarnena sredna Gora Mountain. It has been found out that male boars from the region of sarnena sredna Gora Mountain have an extended, relatively narrow and low skull, with a straight profile line. The lacrimal bone is extended, with a trapezoid shape. concerning their craniological characteristics, male wild boars from the region of sarnena sredna Gora Mountain are attributed to the wild boar population inhabiting North Bulgaria. the basic skull dimensions characterizing its length, height and width are in positive correlation

    Sequence of Potentials Interpolating between the U(5) and E(5) Symmetries

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    It is proved that the potentials of the form β2n\beta^{2n} (with nn being integer) provide a ``bridge'' between the U(5) symmetry of the Bohr Hamiltonian with a harmonic oscillator potential (occuring for n=1n=1) and the E(5) model of Iachello (Bohr Hamiltonian with an infinite well potential, materialized for infinite nn). Parameter-free (up to overall scale factors) predictions for spectra and B(E2) transition rates are given for the potentials β4\beta^4, β6\beta^6, β8\beta^8, corresponding to R4=E(4)/E(2)R_4=E(4)/E(2) ratios of 2.093, 2.135, 2.157 respectively, compared to the R4R_4 ratios 2.000 of U(5) and 2.199 of E(5). Hints about nuclei showing this behaviour, as well as about potentials ``bridging'' the E(5) symmetry with O(6) are briefly discussed. A note about the appearance of Bessel functions in the framework of E(n) symmetries is given as a by-product.Comment: LaTeX, 17 pages, 9 postscript figure

    Six-dimensional Davidson potential as a dynamical symmetry of the symplectic Interacting Vector Boson Model

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    A six-dimensional Davidson potential, introduced within the framework of the Interacting Vector Boson Model (IVBM), is used to describe nuclei that exhibit transitional spectra between the purely rotational and vibrational limits of the theory. The results are shown to relate to a new dynamical symmetry that starts with the Sp(12,R)SU(1,1)×SO(6)Sp(12,R) \supset SU(1,1) \times SO(6) reduction. Exact solutions for the eigenstates of the model Hamiltonian in the basis defined by a convenient subgroup chain of SO(6) are obtained. A comparison of the theoretical results with experimental data for heavy nuclei with transitional spectra illustrates the applicability of the theory.Comment: 9 pages, 4 figure

    q-Analogue of Am1An1Amn1A_{m-1}\oplus A_{n-1}\subset A_{mn-1}

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    A natural embedding Am1An1Amn1A_{m-1}\oplus A_{n-1}\subset A_{mn-1} for the corresponding quantum algebras is constructed through the appropriate comultiplication on the generators of each of the Am1A_{m-1} and An1A_{n-1} algebras. The above embedding is proved in their qq-boson realization by means of the isomorphism between the Aq\mathcal{A}_q^{-} (mn)nAq\sim {\otimes} ^n \mathcal{A}_q^{-}(m)mAq\sim {\otimes}^m\mathcal{A}_q^{-}(n) algebras.Comment: 11 pages, no figures. In memory of professor R. P. Rousse

    In memoriam two distinguished participants of the Bregenz Symmetries in Science Symposia: Marcos Moshinsky and Yurii Fedorovich Smirnov

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    Some particular facets of the numerous works by Marcos Moshinsky and Yurii Fedorovich Smirnov are presented in these notes. The accent is put on some of the common interests of Yurii and Marcos in physics, theoretical chemistry, and mathematical physics. These notes also contain some more personal memories of Yurii Smirnov.Comment: Submitted for publication in Journal of Physics: Conference Serie

    Remarcs on the shape transition from spherical to deformed gamma unstable nuclei

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    Energies and transition probabilities for low lying states in 134^{134}Ba and ^{104Ru were calculated within a hybrid model.The ground and the first 2+2^+ states are described alternatively as a harmonic and anharmonic vibrator states while the remaining states as states with E(5) symmetry. One concludes that a gradual setting of the 'critical' potential yields a better agreement with the experimental data. Very good agreement with the data is obtained for 104^{104}Ru. Comparing the present results with those of E(5) symmetry, it is conspicuous that the present formalism add corrections to the E(5) formalism by bringing the predictions closer to the experimental data. Analytical relationship between the states with U(5) symmetry and those given by the E(5) description is established.Comment: 21 pages, 3 figures, submitted for publicatio

    Unified description of magic numbers of metal clusters in terms of the 3-dimensional q-deformed harmonic oscillator

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    Magic numbers predicted by a 3-dimensional q-deformed harmonic oscillator with Uq(3)>SOq(3) symmetry are compared to experimental data for atomic clusters of alkali metals (Li, Na, K, Rb, Cs), noble metals (Cu, Ag, Au), divalent metals (Zn, Cd), and trivalent metals (Al, In), as well as to theoretical predictions of jellium models, Woods-Saxon and wine bottle potentials, and to the classification scheme using the 3n+l pseudo quantum number. In alkali metal clusters and noble metal clusters the 3-dimensional q-deformed harmonic oscillator correctly predicts all experimentally observed magic numbers up to 1500 (which is the expected limit of validity for theories based on the filling of electronic shells), while in addition it gives satisfactory results for the magic numbers of clusters of divalent metals and trivalent metals, thus indicating that Uq(3), which is a nonlinear extension of the U(3) symmetry of the spherical (3-dimensional isotropic) harmonic oscillator, is a good candidate for being the symmetry of systems of several metal clusters. The Taylor expansions of angular momentum dependent potentials approximately producing the same spectrum as the 3-dimensional q-deformed harmonic oscillator are found to be similar to the Taylor expansions of the symmetrized Woods-Saxon and wine-bottle symmetrized Woods-Saxon potentials, which are known to provide successful fits of the Ekardt potentials.Comment: 23 pages including 7 table

    ΔI=4\Delta I=4 and ΔI=8\Delta I=8 bifurcations in rotational bands of diatomic molecules

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    It is shown that the recently observed ΔI=4\Delta I=4 bifurcation seen in superdeformed nuclear bands is also occurring in rotational bands of diatomic molecules. In addition, signs of a ΔI=8\Delta I=8 bifurcation, of the same order of magnitude as the ΔI=4\Delta I=4 one, are observed both in superdeformed nuclear bands and rotational bands of diatomic molecules.Comment: LaTex twice, 10 pages and 5 PS figures provided upon demand by the Author
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