Browsing by Issue Date, starting with "1999"
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- Cloning, expression, and tissue localisation of prolactin in adult sea bream (Sparus aurata)Publication . Santos, Cecilia; Brinca, Lilia; Ingleton, P. M.; Power, DeborahA major action of prolactin (PRL) in teleost fish is the maintenance of hydromineral balance in euryhaline species in fresh water. The function of PRL in marine teleosts is less certain and unlike euryhaline teleosts, such as tilapia and salmon, there is relatively little information about protein or gene structure. Associated with studies to determine potential functions of PRL, pituitary prolactin cDNA has been cloned and sequenced from sea bream (Sparus aurata), a marine teleost. The sequence obtained spanned 1349 bp and contained an open reading frame encoding a protein of 212 amino acids composed of a putative signal peptide of 24 residues and a mature protein of 188 amino acids. N-terminal sequencing of the native protein confirmed unambiguously the cleavage site, Ala24, Val25, predicted from alignments of the sea bream PRL cDNA with that of other teleosts. The presence of only one form of PRL in sea bream was supported by identification using Northern blots of only a single transcript of 1.35 kb. Reverse transcription and polymerase chain reaction techniques coupled with Southern blot analysis resulted in the detection of PRL in the pituitary but also in the intestine, liver, ovary, and testes.
- Optical modulation at around 1550 nm in an InGaAlAs optical waveguide containing an InGaAs/AlAs resonant tunneling diodePublication . Figueiredo, J. M. L.; Boyd, A. R.; Stanley, C. R.; Ironside, C. N.; McMeekin, S. G.; Leite, A. M. P.We report electroabsorption modulation of light at around 1550 nm in a unipolar InGaAlAs optical waveguide containing an InGaAs/AlAs double-barrier resonant tunneling diode ~RTD!. The RTD peak-to-valley transition increases the electric field across the waveguide, which shifts the core material absorption band edge to longer wavelengths via the Franz–Keldysh effect, thus changing the light-guiding characteristics of the waveguide. Low-frequency characterization of a device shows modulation up to 28 dB at 1565 nm. When dc biased close to the negative differential conductance region, the RTD optical waveguide behaves as an electroabsorption modulator integrated with a wide bandwidth electrical amplifier, offering a potential advantage over conventional pn modulators.
- Photocurrents in P3MeT Schottky barrier diodesPublication . Jones, G. W.; Taylor, D. M.; Gomes, Henrique L.The photocurrent action spectrum of a Schottky diode formed from electrodeposited poly(3-methylthiophene) is shown to follow closely the UV-visible absorption spectrum. At low forward bias, the peak photocurrent asymptotes to the expected square-root dependence on total potential, V-t, across the depletion region. At high reverse bias the superlinear dependence of the photocurrent on V-t suggests that internal photoemission from the rectifying aluminium electrode may be the dominant process.
- Analysis of deep levels in a phenylenevinylene polymer by transient capacitance methodsPublication . Gomes, Henrique L.; Stallinga, Peter; Rost, H.; Holmes, A. B.; Harrison, M. G.; Friend, R. H.Transient capacitance methods were applied to the depletion region of an abrupt asymmetric n(+) -p junction of silicon and unintentionally doped poly[2-methoxy, 5 ethyl (2' hexyloxy) paraphenylenevinylene] (MEH-PPV). Studies in the temperature range 100-300 K show the presence of a majority-carrier trap at 1.0 eV and two minority traps at 0.7 and 1.3 eV, respectively. There is an indication for more levels for which the activation energy could not be determined. Furthermore, admittance data reveal a bulk activation energy for conduction of 0.12 eV, suggesting the presence of an additional shallow acceptor state. (C) 1999 American Institute of Physics. [S0003-6951(99)02308-6].
- As terminações nasais nas actas das vereações de Loulé (séc. XIV-XV)Publication . Cardeira, Esperança; Fernandes, Maria AliceA questão da convergência das terminações -am e -om em -ão tem sido longamente discutida.
- Identification of mandarin hybrids by isozyme and RAPD analysisPublication . Elisiário, P. J.; Justo, E. M.; Leitão, J. M.A cross between the monoembryonic Clementine MA3 SRA 649 used as seed parent and the polyembryonic Carvalhais mandarin used as pollen progenitor was carried out in the SRA INRA-CIRAD, S. Giuliano, Corsica. Cuttings of 61 plants putatively resulting from this cross were sent to the Centro de Citricultura, Fare, Portugal for further agronomic evaluation under field trials. Isozyme analysis allowed the identification of 59 plants as having sexual origin, however, two plants that showed isozyme patterns identical to their seed parent were impossible to identify as being either of zygotic or of somatic origin. Isozymes confirmed Carvalhais mandarin as the pollen parent of 42 progeny plants, while RAPD analysis confirmed Carvalhais paternity over the remaining 19 plants. A fast and low pollutant method for extraction of Citrus total genomic DNA suitable for RAPD analysis is reported. (C) 1999 Elsevier Science B.V. All rights reserved.
- The solution structure of a [3Fe-4S] ferredoxin: oxidised ferredoxin II from desulfovibrio gigasPublication . Goodfellow, B. J.; Macedo, Anjos L.; Rodrigues, Pedro; Moura, Isabel; Wray, Victor; Moura, José J. G.The use of standard 2D NMR experiments in combination with 1D NOE experiments allowed the assignment of 51 of the 58 spin systems of oxidised [3Fe-4S] ferredoxin isolated from Desulfovibrio gigas. The NMR solution structure was determined using data from 1D NOE and 2D NOESY spectra, as distance constraints, and information from the X-ray structure for the spin systems not detected by NMR in torsion angle dynamics calculations to produce a family of 15 low target function structures. The quality of the NMR family, as judged by the backbone r.m.s.d. values, was good (0.80 Å), with the majority of f/c angles falling within the allowed region of the Ramachandran plot. A comparison with the X-ray structure indicated that the overall global fold is very similar in solution and in the solid state. The determination of the solution structure of ferredoxin II (FdII) in the oxidised state (FdIIox) opens the way for the determination of the solution structure of the redox intermediate state of FdII (FdIIint), for which no X-ray structure is available.
- Development of alternative diet for the mass culture of the European cuttlefish Sepia officinalisPublication . Domingues, Pedro Miguel Rodrigues dos Santos; Andrade, José Pedro Andrade e Silva; Lee, Phillip G.O objectivo desta dissertação era o desenvolvimento de dietas económicas que permitissem o cultivo em grande escala do choco, Sepia oficinalis. Esta foi dividida em duas grandes áreas de investigação, referentes aos hábitos alimentares das diversas fases da vida do choco, associados ao tamanho e à idade. A primeira parte focou os aspectos de cultivo de misidáceos para alimentar os juvenis de choco. A segunda parte consistiu em determinar os efeitos de dietas artificiais (em substituição de dietas naturais como camarão ou peixe congelado) no cultivo do choco, e determinar se estas poderiam substituir com sucesso as dietas naturais que são normalmente utilizadas.
- B-splines neural networks assisted PID autotuningPublication . Azevedo, Ana Beatriz da Piedade de; Ruano, AntonioThis paper describes previous works (1), (2), on neural network pid autotuning. Basically, neural networks are employed to supply PID parameters, according to the ITAE criterion, to a standard PID controller.
- Isozyme analysis revealed that the Portuguese mandarin 'Carvalhais' originated as a single clonePublication . Elisiário, P. J.; Santos, G. G.; Guerreiro, A. R.; Ollitrault, P.; Luro, F.; Leitão, J. M.'Carvalhais' mandarin is a well-known Portuguese mandarin used in several Citrus breeding programmes throughout the world. The first step in the implementation of a breeding programme of this variety was to screen for its natural genetic variability. A significant number of adult trees and young seedlings were submitted to isozyme analysis. For better interpretation of the isozyme patterns of 'Carvalhais', several plants resulting from crosses between this Portuguese mandarin cultivar and the monoembryonic mandarin cultivar Clementine MA3 SRA 649, were also analysed. All the analysed trees of 'Carvalhais' showed similar monomorphic patterns for each isozyme system, indicating that this mandarin cultivar originated as a single initial clone. Young seedlings exhibited monomorphic isozyme patterns identical to the adult plants revealing a high level of apomixis in this cultivar. (C) 1999 Elsevier Science B.V. All rights reserved.