The lexicographic treatment of the demonstrative copulative in Sesotho sa Leboa — an exercise in multiple cross-referencing

In this research article an in-depth investigation is presented of the lexicographic treatment of the demonstrative copulative (DC) in Sesotho sa Leboa. This one case study serves as an example to illustrate the so-called 'paradigmatic lemmatisation' of closed-class words in the African languages. The need for such an approach follows a discussion, in Sections 1 and 2 respectively, of the present and missing directions in African-language metalexicography. A theoretical conspectus of the DC in Sesotho sa Leboa is then offered in Section 3, while Section 4 examines the treatment of the DC in the four existing desktop dictionaries for this language. The outcomes from the two latter sections are then used in Section 5, which analyses the problems of and options for a sound lexicographic treatment of the DC in bilingual and monolingual dictionaries. The next two sections proceed with a review of the practical implementation of the DC lemmatisation suggestions in PyaSsaL, i.e. the Pukuntšutlhaloši ya Sesotho sa Leboa 'Explanatory Sesotho sa Leboa Dictionary' — with Section 6 focussing on the hardcopy and Section 7 on the online version. In the process, the very first fully monolingual African-language dictionary on the Internet is introduced. Section 8, finally, concludes briefly. Keywords: lexicography, paradigmatic lemmatisation, african languages, sesotho sa leboa (northern sotho, sepedi), demonstrative copulative, cross-referencing, corpus, monolingual dictionary, bilingual dictionar

Do dictionary users really look up frequent words? — on the overestimation of the value of corpus-based lexicography

An innovative online Swahili–English dictionary project is presented. A careful study of some of the log files attached to this reference work reveals some hitherto unknown as-pects of true dictionary look-up behaviour, which results in the depreciation of the importance of corpora for dictionary making. Three lexicography software modules are advanced to further enhance the success of the online dictionary. Keywords: lexicography, software, online, dictionary, log file, corpus, frequency, rank, correlation, swahili, english, tshwanele

Resonance energy transfer: The unified theory revisited

Resonanceenergy transfer (RET) is the principal mechanism for the intermolecular or intramolecular redistribution of electronic energy following molecular excitation. In terms of fundamental quantum interactions, the process is properly described in terms of a virtual photon transit between the pre-excited donor and a lower energy (usually ground-state) acceptor. The detailed quantum amplitude for RET is calculated by molecular quantum electrodynamical techniques with the observable, the transfer rate, derived via application of the Fermi golden rule. In the treatment reported here, recently devised state-sequence techniques and a novel calculational protocol is applied to RET and shown to circumvent problems associated with the usual method. The second-rank tensor describing virtual photon behavior evolves from a Green’s function solution to the Helmholtz equation, and special functions are employed to realize the coupling tensor. The method is used to derive a new result for energy transfer systems sensitive to both magnetic- and electric-dipole transitions. The ensuing result is compared to that of pure electric-dipole–electric-dipole coupling and is analyzed with regard to acceptable transfer separations. Systems are proposed where the electric-dipole–magnetic-dipole term is the leading contribution to the overall rate

Intramolecular evolution from a locally excited state to an excimer-like state in a multichromophoric dendrimer evidenced by a femtosecond fluorescence upconversion study

A time-resolved fluorescence upconversion study on a polyphenylene dendrimer with eight peryleneimide chromophores on the surface and on a monochromophoric model compound is reported. The time-dependent fluorescence spectra of the dendrimer show that the initial excitation is into a locally excited chromophore. They further indicate the existence of a decay channel that leads to excited state interaction between chromophores in one dendrimer which takes place on a 5 ps timescale