372 research outputs found

    Locally univalent approximations of analytic functions

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    In the present paper, we introduce a measure of the non-univalency of an analytic function, and we use it in order to find the best approximation of analytic function by a locally univalent normalized analytic function.</p

    0+ states and collective bands in 228Th studied by the (p,t) reaction

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    The excitation spectra in the deformed nucleus 228Th have been studied by means of the (p,t)-reaction, using the Q3D spectrograph facility at the Munich Tandem accelerator. The angular distributions of tritons were measured for about 110 excitations seen in the triton spectra up to 2.5 MeV. Firm 0+ assignments are made for 17 excited states by comparison of experimental angular distributions with the calculated ones using the CHUCK3 code. Assignments up to spin 6+ are made for other states. Sequences of states are selected which can be treated as rotational bands and as multiplets of excitations. Moments of inertia have been derived from these sequences, whose values may be considered as evidence of the two-phonon nature of most 0+ excitations. Experimental data are compared with interacting boson model and quasiparticle-phonon model calculations and with experimental data for 229Pa.Comment: 21 pages, 14 figure

    How general are risk preferences? Choices under uncertainty in different domains.

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    We examine the extent to which an individual's actual insurance and investment choices display a stable ranking in willingness to bear risk, relative to his peers, across different contexts. We do so by examining the same individuals' decisions regarding their 401(k) asset allocations and their choices in five different employer-provided insurance domains, including health and disability insurance. We reject the null that there is no domain-general component of preferences. Among the five insurance domains, the magnitude of the domain-general component of preferences appears substantial; we find for example that one's choices in other insurance domains are substantially more predictive of one's choice in a given insurance domain than either one's detailed demographic characteristics or one's claims experience in that domain. However, we find considerably less predictive power between one's insurance choices and the riskiness of one's 401(k) asset allocations, suggesting that the common element of an individual's preferences may be stronger among domains that are "closer" in context. We also find that the relationship between insurance and investment choices appears considerably larger for employees who may be associated with better "financial sophistication." Overall, we view our findings as largely consistent with an important domain-general component of risk preferences.

    Possible experimental signature of octupole correlations in the 02+^+_2 states of the actinides

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    JπJ^{\pi}= 0+^+ states have been investigated in the actinide nucleus 240{}^{240}Pu up to an excitation energy of 3 MeV with a high-resolution (p,t) experiment at EpE_{p}= 24 MeV. To test the recently proposed JπJ^{\pi}= 02+^+_2 double-octupole structure, the phenomenological approach of the spdf-interacting boson model has been chosen. In addition, the total 0+^+ strength distribution and the 0+0^+ strength fragmentation have been compared to the model predictions as well as to the previously studied (p,t) reactions in the actinides. The results suggest that the structure of the 02+^+_2 states in the actinides might be more complex than the usually discussed pairing isomers. Instead, the octupole degree of freedom might contribute significantly. The signature of two close-lying 0+^+ states below the 2-quasiparticle energy is presented as a possible manifestation of strong octupole correlations in the structure of the 02+^+_2 states in the actinides.Comment: 6 pages, 5 figures, published in Phys. Rev. C 88, 041303(R) (2013

    A state of the art of flat-slab frame tests for gravity and lateral loading

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    The research was carried out in preparation of the SlabSTRESS experimental campaign, that is a part of the Transnational Access activities of the SERA (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe) project.This paper presents a critical review of the state of the art of experimental research concerning the seismic response of reinforced concrete flat slab frames. After a summary of tests on connections, the paper examines tests carried out on frames with gravity and cyclic lateral loading, and shake table tests; scaled specimens and one real scale study are included. A discussion of the results reached so far is provided focusing on the global response, the different load types and effects; the ultimate rotations at failure in relation to the gravity shear and a classification of different failure modes for different types of connections. Based on this analysis, the research needs are highlighted. An experimental program launched to address these open questions is described. Further open topics are highlighted.authorsversionpublishe

    Positional Disorder, Spin-Orbit Coupling and Frustration in GaMnAs

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    We study the magnetic properties of metallic GaMnAs. We calculate the effective RKKY interaction between Mn spins using several realistic models for the valence band structure of GaAs. We also study the effect of positional disorder of the Mn on the magnetic properties. We find that the interaction between two Mn spins is anisotropic due to spin-orbit coupling within both the so-called spherical approximation and in the more realistic six band model. The spherical approximation strongly overestimates this anistropy, especially for short distances between Mn ions. Using the obtained effective Hamiltonian we carry out Monte Carlo simulations of finite and zero temperature magnetization and find that, due to orientational frustration of the spins, non-collinear states appear in both valence band approximations for disordered, uncorrelated Mn impurities in the small concentration regime. Introducing correlations among the substitutional Mn positions or increasing the Mn concentration leads to an increase in the remnant magnetization at zero temperature and an almost fully polarized ferromagnetic state.Comment: 17 Pages, 13 Figure
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