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Drainage and deforestation of tropical peat swamp forests (PSF) in Southeast Asia cause carbon emissions and biodiversity loss of global concern. Restoration efforts to mitigate these impacts usually involve peatland rewetting by blocking canals. However, there have been no studies to date of the optimal rewetting approach that will reduce carbon emission whilst also promoting PSF regeneration. Here we present results of a large-scale restoration trial in Sumatra (Indonesia), monitored for 7.5 years. Water levels in a former plantation were raised over an area of 4800 ha by constructing 257 compacted peat dams in canals. We find peat surface subsidence rates in the rewetted restoration area and adjoining PSF to be halved where water tables were raised from ~ − 0.6 m to ~ − 0.3 m, demonstrating the success of rewetting in reducing carbon emission. A total of 57 native PSF tree species were found to spontaneously grow in the most rewetted conditions and in high densities, indicating that forest regrowth is underway. Based on our findings we propose that an effective PSF restoration strategy should follow stepwise rewetting to achieve substantial carbon emission reduction alongside unassisted regrowth of PSF, thereby enabling the peat, forest and canal vegetation to establish a new nature-based ecosystem balance. [ABSTRACT FROM AUTHOR]

For data rates above 100 Mbits s multimode optical fibre systems are generally modal dispersion rather than loss limited and some form of equalization is highly desirable. In this paper a new strategy for the optimum design of an equalized receiver is introduced with the aim of maximizing the repeater spacing. Linear and nonlinear equalizers are briefly reviewed and their relative merits discussed. In the receiver design, Poisson signal statistics and additive Gaussian noise are considered. A new upper bound on the bit error rate which allows an adequate accuracy is proposed. Results obtained for 140 and 560 Mbits s show a noticeable increase of the repeater spacing when the proposed design strategy is introduced. [ABSTRACT FROM AUTHOR]

Cet article calcule la variance de l'erreur de phase en sortie d'une boucle de Costas en modulation numérique à 16 états d'amplitude et de phase ( Maq 16) en présence d'évanouissements sélectifs, représentés par un modèle à trois rayons simplifié. La densité spectrale de puissance du signal d'erreur est calculée par une méthode d'estimation spectrale. La variance de la phase est calculée pour différentes valeurs de la profondeur de l'évanouissement, de son décentrement ainsi que du retard du rayon réfléchi. L'influence d'un correcteur compensant partiellement ou totalement les distorsions d'amplitude est évaluée. Enfin on donne la correspondance entre la variance du bruit de phase et la dégradation des performances. This paper gives the variance of the phase recovered by a conventional quadriphase Costas loop in 16 Qam modulation in the presence of a selective fading, represented as a three rays simplified model. The power spectral density of the phase error is computed using a spectral estimation technique. The phase error variance is evaluated for different values of the fade depth, the location of the maximum attenuation in the frequency band and the delay of the reflected ray. Finally the relation between the performance degradation and phase noise is given, assuming a gaussian p.d.f. of the phase error. [ABSTRACT FROM AUTHOR]