927 resultados para HOMO-LUMO


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Mode of access: Internet.

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Mode of access: Internet.

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Mode of access: Internet.

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Advertising matter: p. [377]-384.

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A comprehensive study has been conducted to compare the adsorptions of alkali metals (including Li, Na, and K) on the basal plane of graphite by using molecular orbital theory calculations. All three metal atoms prefer to be adsorbed on the middle hollow site above a hexagonal aromatic ring. A novel phenomenon was observed, that is, Na, instead of Li or K, is the weakest among the three types of metal atoms in adsorption. The reason is that the SOMO (single occupied molecular orbital) of the Na atom is exactly at the middle point between the HOMO and the LUMO of the graphite layer in energy level. As a result, the SOMO of Na cannot form a stable interaction with either the HOMO or the LUMO of the graphite. On the other hand, the SOMO of Li and K can form a relatively stable interaction with either the HOMO or the LUMO of graphite. Why Li has a relatively stronger adsorption than K on graphite has also been interpreted on the basis of their molecular-orbital energy levels.

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Chimpanzees (Pan troglodytes) and young children (Homo sapiens) have difficulty with double invisible displacements in which an object is hidden in two nonadjacent boxes in a linear array. Experiment 1 eliminated the possibility that chimpanzees' previous poor performance was due to the hiding direction of the displacement device. As in Call (2001), subjects failed double nonadjacent displacements, showing a tendency to select adjacent boxes. In Experiments 2 and 3, chimpanzees and 24-month-old children were tested on a new adaptation of the task in which four hiding boxes were presented in a diamond-shaped array on a vertical plane. Both species performed above chance on double invisible displacements using this format, suggesting that previous poor performance was due to a response bias or inhibition problem rather than a fundamental limitation in representational capacity.

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In the recent four or five years, there have been abrupt and radical changes in the governance of Hungarian higher education. It can then be interesting to assess the state of “homo academicus“ as it looks currently in Hungary. The notion of “homo academicus“ is obvious: it concerns participants in the system of a country’s higher education. The paper as follows still comes back to the definition of “homo academicus“ by referring first to it as occupation, or rather as a profession that can be interpreted in terms of sociology. Secondly, some historic patterns can also be mobilised, based on the assumption that university is a very European institutions that is even rooted in the tradition of the Middle Ages. The elbow-room of seeking for identity and the role to be filled by academics are limited by the effective system of the governance of higher education. It is a key to the chances of academics of meeting the historically corroborated professional standards that they exercise academic freedom. As it cannot be done individually, but in cooperation (through a collegial system), academic freedom is always combined with collective action. The field where this freedom can be exercised can be specified through university autonomy, the lack of which makes a serious barrier to the full development of a character of “homo academicus“. This is now the case in Hungary, the paper suggests. The paper seeks to gain deeper understanding of the character of academics, their vocation and professional roles, and the governance of higher education, serving as the environment for academic activity, by creating a conceptual framework. The paper is established on the results of sociological research and the experience of legal management, although it remains to be of theoretical nature. It criticises the current Hungarian situation of the governance of higher education, arguing for the reconstruction of university autonomy and financial stability. It also emphasises the importance of predictable regulations.

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Acknowledgements We wish to express our gratitude to the National Geographic Society and the National Research Foundation of South Africa for funding the discovery, recovery, and analysis of the H. naledi material. The study reported here was also made possible by grants from the Social Sciences and Humanities Research Council of Canada, the Canada Foundation for Innovation, the British Columbia Knowledge Development Fund, the Canada Research Chairs Program, Simon Fraser University, the DST/NRF Centre of Excellence in Palaeosciences (COE-Pal), as well as by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada, a Young Scientist Development Grant from the Paleontological Scientific Trust (PAST), a Baldwin Fellowship from the L.S.B. Leakey Foundation, and a Seed Grant and a Cornerstone Faculty Fellowship from the Texas A&M University College of Liberal Arts. We would like to thank the South African Heritage Resource Agency for the permits necessary to work on the Rising Star site; the Jacobs family for granting access; Wilma Lawrence, Bonita De Klerk, Merrill Van der Walt, and Justin Mukanku for their assistance during all phases of the project; Lucas Delezene for valuable discussion on the dental characters of H. naledi. We would also like to thank Peter Schmid for the preparation of the Dinaledi fossil material; Yoel Rak for explaining in detail some of the characters used in previous studies; William Kimbel for drawing our attention to the possibility that there might be a problem with Dembo et al.’s (2015) codes for the two characters related to the articular eminence; Will Stein for helpful discussion about the Bayesian analyses; Mike Lee for his comments on this manuscript; John Hawks for his support in organizing the Rising Star workshop; and the associate editor and three anonymous reviewers for their valuable comments. We are grateful to S. Potze and the Ditsong Museum, B. Billings and the School of Anatomical Sciences at the University of the Witwatersrand, and B. Zipfel and the Evolutionary Studies Institute at the University of the Witwatersrand for providing access to the specimens in their care; the University of the Witwatersrand, the Evolutionary Studies Institute, and the South African National Centre of Excellence in PalaeoSciences for hosting a number of the authors while studying the material; and the Western Canada Research Grid for providing access to the high-performance computing facilities for the Bayesian analyses. Last but definitely not least, we thank the head of the Rising Star project, Lee Berger, for his leadership and support, and for encouraging us to pursue the study reported here.