Browsing by Issue Date, starting with "1993"
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- Studies of the species barrier between Drosophila subobscura and D. madeirensis. III. How universal are the rules of speciation?Publication . Khadem, Mahnaz; Krimbas, Costas B.The prevalence of Haldane's rule and the large effect of the X chromosome are examined by analysing the genetics of seven abnormal characters in interspecies hybrids between D. subobscura and D. madeirensis. In two cases Haldane's rule is not obeyed (viability and abnormality of the head). In all characters except the abnormal abdominal tergites, an important effect of the X chromosome is observed. There is an asymmetry in the importance of the effect of the X chromosome. The X of D. madeirensis origin induces abnormality mostly in a mixed background. TheY chromosome plays an important role in determining male sterility.
- On the use of Fourier transform with acoustical fieldsPublication . Casimiro, António Manuel E. S.; Azevedo, Joaquim A. R.The Fourier Transform is a powerful tool to deal with the radiated far field pattern of source distributions [l], PI. In this paper it is made a theoretical introduction to the possibility of using the Fourier Transform to study the fields produced by distributions, either continuous or discrete, of acoustical source distributions. With this new approach we can have a deep insight in the field and it is possible to develop and simplify methods of analysis and synthesis of fields produced by acoustical sources. All the procedure is based on the Theorem of the Small Complex Translation presented. In this case, and with a convenient choice of variables, the far field pattern is related with an window on the Fourier Transform of source distribution. The analysis and synthesis are made using the Fourier Transform firoprieties and the tools provided by the signal processing theory using the Fourier Transform
- The phylogeny of nine species of the Drosophila obscura group inferred by the banding homologies of the chromosomal regions. IV. Element CPublication . Brehm, António; Krimbas, Costas B.Homologies of the sections of the polytene chromosomes of element C, among several species of the obscura group of the genus Drosophila, were established according to the similarity of their banding patterns. The information gathered was used to construct an unrooted phylogenetic tree based on qualitative criteria. This tree is compared to three other similar trees derived from independent information provided by the study of chromosomal elements B, D and E. The general congruence of the patterns of these trees proves the well-foundedness of this approach. A single exception to this congruence is discussed. Finally a consensus tree, encapsulating information from all chromosomal elements, is presented and its topology is compared to those derived from electrophoretic data.
- Liver coccidiosis in some marine fish species from Scottish watersPublication . Costa, Graça Maria Pereira da
- Single particle theory of AG-Synchrotrons taking into account momentum dependence and non-linearities of the focussing forcePublication . Hagel, Johannes; Schnizer, Bernhard
- Identifying vulnerable industries and regions: the proposed European single market and Portuguese manufacturingPublication . Pereira, Pedro Telhado; Seabra, Maria do Carmo