preparations for the Rosetta radio science investigations

Models of the thermal behavior of a cometary nucleus, the evolution of the neutral gas coma, the ionized cometary coma and of the interaction of the cometary plasma with the solar wind are studied in this work. The general aim is to develop a global model of the comet and its environment in order to characterize the physical conditions around comets 67P/Churyumov-Gerasimenko and 46P/Wirtanen with respect to the heliocentric distance. The results also provide estimates of the effects of the cometary environment on the radio science investigations experiment (RSI) aboard the spacecraft Rosetta. After the launch that is scheduled for February 2004, the Rosetta mission is planned to encounter comet 67P/Churyumov-Gerasimenko and accompany it on its orbit. Comet 46P/Wirtanen has been the original target comet, but serves now as back-up target due to the postponement of the Rosetta launch in January 2003. The model of the heat diffusion within the cometary nucleus is one-dimensional. A grid of one-dimensional models is distributed over the nucleus in order to determine the temperature distribution and the sublimation characteristics of the comet on the whole surface of the comet. A heat balance equation is applied as boundary condition on the surface. Many parameters that have to be accounted for in a heat diffusion model are not precisely known to date. The variation of these parameters within reasonable limits yields a wide range of possible results. The heat diffusion within the cometary nucleus is derived from an energy conservation equation that includes heat conduction through the porous cometary material and heat convection due to the transport of latent heat by the gas phase within the nucleus. Model results are evaluated by a comparison of modeled and observed global gas production rates ...thesi

Search for three alpha states around an 16^{16}O core in 28^{28}Si

We investigate the existence of weakly coupled gas-like states comprised of three $\alpha$ particles around an $^{16}$O core in $^{28}$Si. We calculate the excited states in $^{28}$Si using the multi-configuration mixing method based on the $^{16}$O + 3$\alpha$ cluster model. We also include the $^{16}$O + $^{12}$C and $^{24}$Mg + $\alpha$ basis wave functions prepared by the generator coordinate method. To identify the gas-like states, we calculate the isoscalar monopole transition strengths and the overlap of the obtained states with the geometrical cluster wave function and the Tohsaki-Horiuchi-Schuck-R\"{o}pke (THSR) wave function. The results show that the obtained fourth and twelfth states significantly overlap with the THSR wave function. These two states clearly coexist with the $^{16}$O + $^{12}$C cluster states, emerging at similar energies. The calculated isoscalar monopole strengths between those two states are significantly large, indicating that the states are members of the excitation mode. Furthermore, the calculated root-mean-squared (RMS) radii for these states also suggest that a layer of gas-like three $\alpha$ particles could exist around the surface of the $^{16}$O core, which can be described as a "two-dimensional gas" in the intermediate state before the Hoyle-like three $\alpha$ states emerge.Comment: 5 pages, 3 figure

Within-person structures of daily cognitive performance cannot be inferred from between-person structures of cognitive abilities

First published online: 09 June 2020Over a century of research on between-person differences has resulted in the consensus that human cognitive abilities are hierarchically organized, with a general factor, termed general intelligence or "g," uppermost. Surprisingly, it is unknown whether this body of evidence is informative about how cognition is structured within individuals. Using data from 101 young adults performing nine cognitive tasks on 100 occasions distributed over six months, we find that the structures of individuals' cognitive abilities vary among each other, and deviate greatly from the modal between-person structure. Working memory contributes the largest share of common variance to both between- and within-person structures, but the g factor is much less prominent within than between persons. We conclude that between-person structures of cognitive abilities cannot serve as a surrogate for within-person structures. To reveal the development and organization of human intelligence, individuals need to be studied over time

The antecedents of post-initial adoption behavior in a S-D logic context: leveraging the power of the viral metaphor to advance service innovation adoption

Repercussions of innovation adoption and diffusion studies have long been imperative to the success of novel introductions. However, perceptions and deductions of current innovation understandings have been changing over time. The paradigm shift from the goods-dominant (G-D) logic to the service-dominant (S-D) logic potentially makes the distinction between product (goods) innovation and service innovation redundant as the S-D logic lens views all innovations as service innovations (Vargo and Lusch, 2004; 2008; Lusch and Nambisan, 2015). From this perspective, product innovations are in essence service innovations, as goods serve as mere distribution mechanisms to deliver service. Nonetheless, the transition to such a broadened and transcending view of service innovation necessitates concurrently a change in the underlying models used to investigate innovation and its subsequent adoption. The present research addresses this gap by engendering a novel model for the most crucial period of service diffusion within the S-D logic context – the post-initial adoption phase, which demarcates an individual’s behavior after the initial adoption decision of a service. As a wellfounded understanding of service diffusion and the complementary innovation adoption still lingers in its infancy, the current study develops a model based on interdisciplinary domains mapping. Here fore, knowledge of the relatively established viral source domain is mapped to the comparatively undetermined target domain of service innovation adoption. To assess the model and test the importance of the explanatory variables, survey data from 750 respondents of a bank in Northern Germany is scrutinized by means of Structural Equation Modeling (SEM). The findings reveal that the continuance intention of a customer, actual usage of the service and the customer influencer value all constitute important postinitial adoption behavior that have meaningful implications for a successful service adoption. Second, the four constructs customer influencer value, organizational commitment, perceived usefulness and service customization are evidenced to have a differential impact on a iv customer’s post-initial adoption behavior. Third, this study indicates that post-initial adoption behavior further underlies the influence of a user’s age and besides that is also provoked by the internal and external environments of service adoption. Finally, this research amalgamates the broad view of service innovation by Nambisan and Lusch (2015) with the findings ensuing this enquiry’s model to arrive at a framework that it both, generalizable and practically applicable. Implications for academia and practitioners are captured along with avenues for future research

Enhanced excitation of Giant Pairing Vibrations in heavy-ion reactions induced by weakly-bound projectiles

The use of radioactive ion beams is shown to offer the possibility to study collective pairing states at high excitation energy, which are not usually accessible with stable projectiles because of large energy mismatch. In the case of two-neutron stripping reactions induced by 6He, we predict a population of the Giant Pairing Vibration in 208Pb or 116Sn with cross sections of the order of a millibarn, dominating over the mismatched transition to the ground state.Comment: 6 pages, 4 figure

Di-neutron elastic transfer in the 4He(6He,6He)4He reaction

Elastic $^{6}$He+$^4$He data measured at $E_{\rm c.m.}=11.6,$ 15.9, and 60.3 MeV have been analyzed within the coupled reaction channels (CRC) formalism, with the elastic-scattering and two-neutron ($2n$) transfer amplitudes coherently included. Contributions from the direct (one-step) and sequential (two-step) $2n$-transfers were treated explicitly based on a realistic assumption for the $2n$-transfer form factor. The oscillatory pattern observed in $^4$He($^6$He,$^6$He)$^4$He angular distribution at low energies was found to be due to an interference between the elastic scattering and $2n$-transfer amplitudes. Our CRC analysis shows consistently that the direct $2n$-transfer strongly dominates over the sequential transfer and thus confirms the dominance of 2$n-^4$He configuration over the $n-^5$He one in the $^6$He wave function. This result suggests a strong clusterization of the two valence neutrons and allows, therefore, a reliable estimate for the \emph{di-neutron} spectroscopic amplitude.Comment: Accepted for publication in Phys. Lett.