156,009 research outputs found

    Deglaciation constraints in the Parâng Mountains, Southern Romania, using surface exposure dating

    Get PDF
    Cosmogenic nuclide surface exposure ages have been widely used to constrain glacial chronologies in the European regions. This paper brings new evidence that the Romanian Carpathians sheltered mountain glaciers in their upper valleys and cirques until the end of the last glaciation. Twenty-four 10Be surface exposure ages were obtained from boulders on moraine crests in the central area of the Parâng Mountains, Southern Carpathians. Exposure ages were used to constrain the timing of the deglaciation events during the Late Glacial. The lowest boulders yielded an age of 13.0 ± 1.1 (1766 m) and final deglaciation occurred at 10.2 ± 0.9 ka (2055 m). Timing of the Late Glacial events and complete deglaciation reported in this study are consistent with, and confirm, previously reported ages of deglaciation within the Carpathian and surrounding European region

    Size dependence of second-order hyperpolarizability of finite periodic chain under Su-Schrieffer-Heeger model

    Full text link
    The second hyperpolarizability γN(−3ωω,ω,ω)\gamma_N(-3\omega\omega,\omega,\omega) of NN double-bond finite chain of trans-polyactylene is analyzed using the Su-Schrieffer-Heeger model to explain qualitative features of the size-dependence behavior of γN\gamma_N. Our study shows that γN/N\gamma_N/N is {\it nonmonotonic} with NN and that the nonmonotonicity is caused by the dominant contribution of the intraband transition to γN\gamma_N in polyenes. Several important physical effects are discussed to reduce quantitative discrepancies between experimental and our resultsComment: 3 figures, 1 tabl

    Singularity problem in f(R) model with non-minimal coupling

    Full text link
    We consider the non-minimal coupling between matter and the geometry in the f(R) theory. In the new theory which we established, a new scalar ψ\psi has been defined and we give it a certain stability condition. We intend to take a closer look at the dark energy oscillating behavior in the de-Sitter universe and the matter era, from which we derive the oscillating frequency, and the oscillating condition. More importantly, we present the condition of coupling form that the singularity can be solved. We discuss several specific coupling forms, and find logarithmic coupling with an oscillating period ΔT∼Δz\Delta T\sim\Delta z in the matter era z>4z>4, can improve singularity in the early universe. The result of numerical calculation verifies our theoretic calculation about the oscillating frequency. Considering two toy models, we find the cosmic evolution in the coupling model is nearly the same as that in the normal f(R) theory when lna>4lna>4. We also discuss the local tests of the non-minimal coupling f(R) model, and show the constraint on the coupling form.Comment: 13 pages, 4 figure

    Stocking, Enhancement, and Mariculture of Penaeus orientalis and Other Species in Shanghai and Zhejiang Provinces, China

    Get PDF
    China's marine aquaculture landings provide only 18% of its combined freshwater and amrine capture and culture landings, at a per-capita consumption of only 3.2 kg/yr out of a total of 18.1 kg/yr. We described development and some of the results of long-term mariculture and stocking/enhancement projects that have been underway for up to 20 years in the Hangzhou Bay area. Penaeus orientalis (also referred to as P. chinensis) stocking provided up to 400 t/yr, at a total cost-benefit ratio of up to 8 Yuan of landed shrimp per Yuan invested in shrimp stocking. Over 40 t of Penaeus orientalis were produced commercially in 1993, with proceeds being used to fund mariculture and fisheries research. Large scale edible jellyfish restocking is also underway, while semicommercial culture of abalone, Haliotis diversicolor, has been successful. Technical problems limitig mariculture have been solved successfully for some species

    Holomorphic Poisson Manifolds and Holomorphic Lie Algebroids

    Full text link
    We study holomorphic Poisson manifolds and holomorphic Lie algebroids from the viewpoint of real Poisson geometry. We give a characterization of holomorphic Poisson structures in terms of the Poisson Nijenhuis structures of Magri-Morosi and describe a double complex which computes the holomorphic Poisson cohomology. A holomorphic Lie algebroid structure on a vector bundle A→XA\to X is shown to be equivalent to a matched pair of complex Lie algebroids (T0,1X,A1,0)(T^{0,1}X,A^{1,0}), in the sense of Lu. The holomorphic Lie algebroid cohomology of AA is isomorphic to the cohomology of the elliptic Lie algebroid T0,1X⋈A1,0T^{0,1}X\bowtie A^{1,0}. In the case when (X,π)(X,\pi) is a holomorphic Poisson manifold and A=(T∗X)πA=(T^*X)_\pi, such an elliptic Lie algebroid coincides with the Dirac structure corresponding to the associated generalized complex structure of the holomorphic Poisson manifold.Comment: 29 pages, v2: paper split into two, part 1 of 2, v3: two references added, v4: final version to appear in International Mathematics Research Notice
    • …
    corecore