Exponential decay of spin-spin correlation between distant defect states produced by contour hydrogenation of polycyclic aromatic hydrocarbon molecules

The first few low-lying spin states of alternant polycyclic aromatic hydrocarbon (PAH) molecules of several shapes showing defect states induced by contour hydrogenation have been studied both by ab initio methods and by a precise numerical solution of Pariser-Parr-Pople (PPP) interacting model. In accordance with Lieb's theorem, the ground state shows a spin multiplicity equal to one for balanced molecules, and it gets larger values for imbalanced molecules (that is, when the number of π electrons on both subsets is not equal). Furthermore, we find a systematic decrease of the singlet-triplet splitting as a function of the distance between defects, regardless of whether the ground state is singlet or triplet. For example, a splitting smaller than 0.001 eV is obtained for a medium size C46H28 PAH molecule (di-hydrogenated [11]phenacene) showing a singlet ground state. We conclude that π electrons unbound by lattice defects tend to remain localized and unpaired even when long-range Coulomb interaction is taken into account. Therefore they show a biradical character (polyradical character for more than two defects) and should be studied as two or more local doublets. The implications for electron transport are potentially important since these unpaired electrons can trap traveling electrons or simply flip their spin at a very small energy cost.

The ectoparasitic mite Tropilaelaps mercedesae reduces western honey bee, Apis mellifera, longevity and emergence weight, and promotes Deformed wing virus infections

Historically an ectoparasite of the native Giant honey bee Apis dorsata, the mite Tropilaelaps mercedesae has switched hosts to the introduced western honey bee Apis mellifera throughout much of Asia. Few data regarding lethal and sub-lethal effects of T. mercedesae on A. mellifera exist, despite its similarity to the devastating mite Varroa destructor. Here we artificially infested worker brood of A. mellifera with T. mercedesae to investigate lethal (longevity) and sub-lethal (emergence weight, Deformed wing virus (DWV) levels and clinical symptoms of DWV) effects of the mite on its new host. The data show that T. mercedesae infestation significantly reduced host longevity and emergence weight, and promoted both DWV levels and associated clinical symptoms. Our results suggest that T. mercedesae is a potentially important parasite to the economically important A. mellifera honey bee.

Systems feasibility study: states' assistance in defect recall campaigns. Final report, Volume I.

National Highway Traffic Safety Administration, Washington, D.C.

Systems feasibility study: states' assistance in defect recall campaigns. Final report, Volume II.

National Highway Traffic Safety Administration, Washington, D.C.

Systems feasibility study: states' assistance in defect recall campaigns. Final report, Volume III.

National Highway Traffic Safety Administration, Washington, D.C.

Systems feasibility study: states' assistance in defect recall campaigns. Final report, Volume IV.

National Highway Traffic Safety Administration, Washington, D.C.

Motor vehicle safety defect recall campaigns from January 1, 1971 to December 31, 1971; reported to the National Highway Traffic Safety Administration by domestic and foreign vehicle manufacturers.

Mode of access: Internet.

Motor vehicle safety defect recall campaigns reported to the National Highway Traffic Safety Administration by domestic and foreign vehicle manufacturers, January 1, 1972 to December 31, 1972.

Mode of access: Internet.

Motor vehicle safety defect recall campaigns reported to the National Highway Traffic Safety Administration by domestic and foreign vehicle manufacturers. January 1, 1973 to December 31, 1973.

Mode of access: Internet.

Motor vehicle safety defect recall campaigns reported to the National Highway Traffic Safety Administration by domestic and foreign vehicle manufacturers. January 1, 1974 to December 31, 1974.

Mode of access: Internet.

Motor vehicle safety defect recall campaigns reported to the National Highway Traffic Safety Administration by domestic and foreign vehicle manufacturers. January 1, 1975 to December 31, 1975.

Mode of access: Internet.

Motor vehicle safety defect recall campaigns reported to the National Highway Traffic Safety Administration by domestic and foreign vehicle manufacturers. January 1, 1976 to December 31, 1976.

Mode of access: Internet.

Mendelism and the problem of mental defect.

Original imprint covered by label.