137 research outputs found

    Dispersión de los reproductores del ansar de Ross en la metapoblación del golfo de la Reina Maud

    Get PDF
    We estimated rates of breeding philopatry and complementary dispersal within the Queen Maud Gulf metapopulation of Ross’s Geese (Chen rossii) using multistate modeling of neckband observations at five breeding colonies, 1999–2003. Probability of philopatry was female–biased, but varied among colonies. Probabilies of annual movement among breeding colonies ranged 0.02 to 0.14 for females and 0.12 to 0.38 for males and was substantially higher than expected. These estimates (1) underscore the potential for dispersal to alter breeding distribution, (2) demonstrates that the influence of immigration on colony–specific rates of population growth is nontrivial, and (3) provides behavioral evidence for extensive gene flow among subpopulations. Sex differences in apparent survival estimated from multistate models likely resulted from a combination of higher rates of neckband loss by males compared to females, and higher rates of permanent emigration by males from our study area.Estimamos las tasas de filopatría de reproducción y la dispersión complementaria del ansar de Ross (Chen rossii) en la metapoblación del golfo de la Reina Maud utilizando la modelación multiestado a partir de las observaciones de animales marcados en el cuello en cinco colonias de reproducción, 1999–2003. La probabilidad de filopatría presentaba un sesgo a favor de las hembras, pero variaba de una colonia a otra. Las probabilidades de movimiento anual entre las colonias de reproducción oscilaban entre el 0,02 y el 0,14 para las hembras, y entre el 0,12 y el 0,38 para los machos, siendo considerablemente superiores a lo previsto. Estas estimaciones 1) subrayan las posibilidades de que la dispersión modifique la distribución de reproducción, 2) demuestran que la influencia de la inmigración en las tasas de crecimiento poblacional de cada colonia no es irrelevante y 3) proporcionan evidencia conductual acerca de un amplio flujo genético entre subpoblaciones. Las diferencias por sexo en la supervivencia aparente estimadas a partir de modelos multiestado probablemente fueron debidas a una combinación de tasas más elevadas de pérdida de marcaje en el cuello por parte de los machos en comparación con las hembras, y a tasas más elevadas de emigración permanente por parte de los machos de nuestra área de estudio

    The induced representations of Brauer algebra and the Clebsch-Gordan coefficients of SO(n)

    Get PDF
    Induced representations of Brauer algebra Df(n)D_{f}(n) from Sf1×Sf2S_{f_{1}}\times S_{f_{2}} with f1+f2=ff_{1}+f_{2}=f are discussed. The induction coefficients (IDCs) or the outer-product reduction coefficients (ORCs) of Sf1×Sf2↑Df(n)S_{f_{1}}\times S_{f_{2}}\uparrow D_{f}(n) with f≤4f\leq 4 up to a normalization factor are derived by using the linear equation method. Weyl tableaus for the corresponding Gel'fand basis of SO(n) are defined. The assimilation method for obtaining CG coefficients of SO(n) in the Gel'fand basis for no modification rule involved couplings from IDCs of Brauer algebra are proposed. Some isoscalar factors of SO(n)⊃SO(n−1)SO(n)\supset SO(n-1) for the resulting irrep [λ1, λ2, λ3, λ4,0˙][\lambda_{1},~\lambda_{2},~ \lambda_{3},~\lambda_{4},\dot{0}] with $\sum\limits_{i=1}^{4}\lambda_{i}\leq .Comment: 48 pages latex, submitted to Journal of Phys.

    More on coupling coefficients for the most degenerate representations of SO(n)

    Full text link
    We present explicit closed-form expressions for the general group-theoretical factor appearing in the alpha-topology of a high-temperature expansion of SO(n)-symmetric lattice models. This object, which is closely related to 6j-symbols for the most degenerate representation of SO(n), is discussed in detail.Comment: 9 pages including 1 table, uses IOP macros Update of Introduction and Discussion, References adde

    Componentes de la tasa de crecimiento poblacional en el negrón especulado de Saskatchewan, Canadá

    Get PDF
    Breeding range and abundance of White–winged Scoters (Melanitta fusca deglandi) have declined in northwestern North America. Hypotheses proposed to account for this trend are that survival and/or recruitment of females had declined. Thus, we used a reverse–time capture–recapture approach to directly estimate survival, seniority and capture probabilities for females of breeding age at Redberry Lake, Saskatchewan, Canada for 1975–1980 and 2000–2003. We also estimated population size of breeding females for 1975–1985 and 2000–2003 using capture–recapture data. Initially, this local population was in serious decline [95% CL ( ) = 0.89 ± 0.09], but has since stabilized and may be slowly increasing [95% CL ( ) = 1.07 ± 0.11]. This reversal in trajectory apparently resulted from increased recruitment rather than increased apparent survival. Importantly, recent recruitment of adult females appeared to be driven solely by immigration of adult females with no detectable in situ recruitment, suggesting a hypothesis that the local population is being rescued by females produced elsewhere.El rango reproductivo y la abundancia del negrón especulado (Melanitta fusca deglandi) han disminuido en la zona noroeste de América del Norte. La hipótesis propuesta para explicar esta tendencia es que se ha producido una disminución en la supervivencia y/o el reclutamiento de hembras. Por consiguiente, utilizamos un enfoque de captura–recaptura con el tiempo invertido para estimar directamente la supervivencia, la jerarquía y las probabilidades de captura de las hembras en edad reproductora del lago Redberry, Saskatchewan, Canadá, durante los periodos 1975–1980 y 2000– 2003. También estimamos el tamaño poblacional de las hembras reproductoras durante los periodos 1975–1985 y 2000–2003, mediante el empleo de datos de captura–recaptura. En un principio, esta población local experimentó una importante disminución [95% CL ( ) = 0,89 ± 0,09], pero posteriormente se estabilizó, y es posible que poco a poco vaya aumentando [95% CL ( ) = 1,07 ± 0,11]. Por lo visto, la inversión de esta trayectoria se produjo como consecuencia de un mayor reclutamiento, en lugar de una mayor supervivencia aparente. Es importante destacar que el reclutamiento reciente de hembras adultas parece haber obedecido exclusivamente a la migración de hembras adultas sin un reclutamiento detectable in situ, lo que sugiere la hipótesis de que la población local está siendo rescatada por hembras procedentes de otros lugares

    Breeding dispersal by Ross’s geese in the Queen Maud Gulf metapopulation

    Get PDF
    We estimated rates of breeding philopatry and complementary dispersal within the Queen Maud Gulf metapopulation of Ross’s Geese (Chen rossii) using multistate modeling of neckband observations at five breeding colonies, 1999–2003. Probability of philopatry was female–biased, but varied among colonies. Probabilies of annual movement among breeding colonies ranged 0.02 to 0.14 for females and 0.12 to 0.38 for males and was substantially higher than expected. These estimates (1) underscore the potential for dispersal to alter breeding distribution, (2) demonstrates that the influence of immigration on colony–specific rates of population growth is nontrivial, and (3) provides behavioral evidence for extensive gene flow among subpopulations. Sex differences in apparent survival estimated from multistate models likely resulted from a combination of higher rates of neckband loss by males compared to females, and higher rates of permanent emigration by males from our study area

    On the Implementation of the Canonical Quantum Simplicity Constraint

    Full text link
    In this paper, we are going to discuss several approaches to solve the quadratic and linear simplicity constraints in the context of the canonical formulations of higher dimensional General Relativity and Supergravity developed in our companion papers. Since the canonical quadratic simplicity constraint operators have been shown to be anomalous in any dimension D>2, non-standard methods have to be employed to avoid inconsistencies in the quantum theory. We show that one can choose a subset of quadratic simplicity constraint operators which are non-anomalous among themselves and allow for a natural unitary map of the spin networks in the kernel of these simplicity constraint operators to the SU(2)-based Ashtekar-Lewandowski Hilbert space in D=3. The linear constraint operators on the other hand are non-anomalous by themselves, however their solution space will be shown to differ in D=3 from the expected Ashtekar-Lewandowski Hilbert space. We comment on possible strategies to make a connection to the quadratic theory. Also, we comment on the relation of our proposals to existing work in the spin foam literature and how these works could be used in the canonical theory. We emphasise that many ideas developed in this paper are certainly incomplete and should be considered as suggestions for possible starting points for more satisfactory treatments in the future.Comment: 30 pages, 2 figures. v2: Journal version. Comparison to existing approaches added. Discussion extended. References added. Sign error in equation (2.15) corrected. Minor clarifications and correction

    The Drinfeld double gl(n) \oplus t_n

    Full text link
    The two isomorphic Borel subalgebras of gl(n), realized on upper and lower triangular matrices, allow us to consider the gl(n) \opus t_n algebra as a self-dual Drinfeld double. Compatibility conditions impose the choice of an orthonormal basis in the Cartan subalgebra and fix the basis of gl(n). A natural Lie bialgebra structure on gl(n) is obtained, that offers a new perspective for its standard quantum deformation.Comment: 8 page

    Ground-γ\gamma band coupling in heavy deformed nuclei and SU(3) contraction limit

    Full text link
    We derive analytic expressions for the energies and B(E2)B(E2)-transition probabilities in the states of the ground and γ\gamma bands of heavy deformed nuclei within a collective Vector-Boson Model with SU(3) dynamical symmetry. On this basis we examine the analytic behavior of the SU(3) energy splitting and the B(E2) interband transition ratios in the SU(3) contraction limits of the model. The theoretical analyses outline physically reasonable ways in which the ground-γ\gamma band coupling vanishes. The experimental data on the lowest collective states of even-even rare earth nuclei and actinides strongly support the theoretical results. They suggest that a transition from the ground-γ\gamma band coupling scheme to a scheme in which the ground band is situated in a separate irreducible representation of SU(3) should be realized towards the midshell regions. We propose that generally the SU(3) group contraction process should play an important role for such a kind of transitions in any collective band coupling scheme in heavy deformed nuclei.Comment: 24 pages (LaTeX), 7 figures (12 postscript files

    From Food to Offspring Down: Tissue-Specific Discrimination and Turn-Over of Stable Isotopes in Herbivorous Waterbirds and Other Avian Foraging Guilds

    Get PDF
    Isotopic discrimination and turn-over are fundamental to the application of stable isotope ecology in animals. However, detailed information for specific tissues and species are widely lacking, notably for herbivorous species. We provide details on tissue-specific carbon and nitrogen discrimination and turn-over times from food to blood, feathers, claws, egg tissues and offspring down feathers in four species of herbivorous waterbirds. Source-to-tissue discrimination factors for carbon (δ13C) and nitrogen stable isotope ratios (δ15N) showed little variation across species but varied between tissues. Apparent discrimination factors ranged between −0.5 to 2.5‰ for δ13C and 2.8 to 5.2‰ for δ15N, and were more similar between blood components than between keratinous tissues or egg tissue. Comparing these results with published data from other species we found no effect of foraging guild on discrimination factors for carbon but a significant foraging-guild effect for nitrogen discrimination factors

    Constraining the Evolution of Zz Ceti

    Get PDF
    We report our analysis of the stability of pulsation periods in the DAV star (pulsating hydrogen atmosphere white dwarf) ZZ Ceti, also called R548. On the basis of observations that span 31 years, we conclude that the period 213.13 s observed in ZZ Ceti drifts at a rate dP/dt ≤ (5:5 ± 1:9) x 10-15 s s-1, after correcting for proper motion. Our results are consistent with previous Ṗ values for this mode and an improvement over them because of the larger time base. The characteristic stability timescale implied for the pulsation period is ⎸P / Ṗ ⎸=⎹≥ 1:2 Gyr, comparable to the theoretical cooling timescale for the star. Our current stability limit for the period 213.13 s is only slightly less than the present measurement for another DAV, G117-B15A, for the period 215.2 s, establishing this mode in ZZ Ceti as the second most stable optical clock known, comparable to atomic clocks and more stable than most pulsars. Constraining the cooling rate of ZZ Ceti aids theoretical evolutionary models and white dwarf cosmochronology. The drift rate of this clock is small enough that we can set interesting limits on reflex motion due to planetary companions
    • …
    corecore