Label Space Reduction in All-Optical Label Switchiing Networks

Report for the scientific sojourn at the Department of Information Technology (INTEC) at the Ghent University, Belgium, from january to june 2007. All-Optical Label Swapping (AOLS) forms a key technology towards the implementation of All-Optical Packet Switching nodes (AOPS) for the future optical Internet. The capital expenditures of the deployment of AOLS increases with the size of the label spaces (i.e. the number of used labels), since a special optical device is needed for each recognized label on every node. Label space sizes are affected by the wayin which demands are routed. For instance, while shortest-path routing leads to the usage of fewer labels but high link utilization, minimum interference routing leads to the opposite. This project studies and proposes All-Optical Label Stacking (AOLStack), which is an extension of the AOLS architecture. AOLStack aims at reducing label spaces while easing the compromise with link utilization. In this project, an Integer Lineal Program is proposed with the objective of analyzing the softening of the aforementioned trade-off due to AOLStack. Furthermore, a heuristic aiming at finding good solutions in polynomial-time is proposed as well. Simulation results show that AOLStack either a) reduces the label spaces with a low increase in the link utilization or, similarly, b) uses better the residual bandwidth to decrease the number of labels even more.

Ecoetiques de serveis als establiments hotelers del Parc Natural de l'Alt Pirineu

En el present projecte s’analitza el turisme i la seva relació amb la figura del Parc Natural de l’Alt Pirineu (a partir d’ara PNAP). A la zona d’estudi el turisme és una de les principals activitats econòmiques, donat el notable valor ecologico-cultural de l’indret. L’activitat turística al PNAP és molt diversa, és per aquest motiu que s’observen diverses repercussions en l’entorn segons la tipologia de turisme que es doni. Donada aquesta realitat, l’estudi que es presenta està centrat en el sector hoteler de l’àmbit d’influència del PNAP. D’aquesta forma, s’analitza i diagnostica l’estat de qualitat ambiental dels hotels i pensions que componen el sector. Les eines emprades en aquest estudi han estat dues. Primerament, s’avalua la implantació del Distintiu de Garantia de Qualitat Ambiental (a partir d’ara DGQA). El DGQA és una ecoetiqueta de serveis, de recent creació, que atorga la Generalitat de Catalunya a partir de la revisió de l’establiment per mitjà d’un tècnic autoritzat. En segon terme, s’ha creat i emprat un producte anomenat Enquesta Bàsica d’Auto-xequeig de Qualitat Ambiental (a partir d’ara EBAQA). L’EBAQA té una doble finalitat. Per una banda respon a la necessitat d’autodiagnosi que tenen els propietaris, al ser aquests qui realitzen l’enquesta. Per altra banda, permet determinar quin és l’estat de qualitat ambiental del sector hoteler a la zona d’estudi a partir de l’avaluació de 35 dels 67 establiments existents a l’àmbit d’influència del PNAP, el qual representa una mostra del 61%.

The metazoan parasites of Stellifer minor (Tschudi, 1844): an ecological approach

A quantitative and qualitative analysis of the parasite fauna of the sciaenid Stellifer minor (Tschudi) from Chorrillos, Peru, was made. Some characteristics of the infectious processes, in terms of intensity and prevalence of infection, as a function of host sex and size, are given. Moreover, comments on the characteristics of the parasite fauna, related with host role in the marine food webs are included. The parasite fauna of Stellifer minor taken of Chorrillos, Peru, include the monogeneans Pedocotyle annakohni, Pedocotyle bravoi, Rhamnocercus sp. and Cynoscionicola sp., the digenean Helicometra fasciata, the adult acantocephalan Rhadinorhynchus sp. and the larval Corynosoma sp., the nematode Procamallanus sp., the copepods Caligus quadratus, Clavellotis dilatata and Bomolochus peruensis and one unidentified isopod of the family Cymothoidae. A distinctive characteristic of the parasite fauna (Metazoa) of S. minor is the almost absence of larval forms.

Ecological-economic modelling of interactions between wild and commercial bees and pesticide use

The decline in extent of wild pollinators in recent years has been partly associated with changing farm practices and in particular with increase of pesticide use. In this paper we combine ecological modelling with economic analysis of a single farm output under the assumption that both pollination and pest control are essential inputs. We show that the drive to increase farm output can lead to a local decline in the wild bee population. Commercial bees are often considered an alternative to wild pollinators, but we show that their introduction can lead to further decline and finally local extinction of wild bees. The transitions between different outcomes are characterised by threshold behaviour and are potentially difficult to predict and detect in advance. Small changes in economic (input prices) and ecological (wild bees carrying capacity and effect of pesticides on bees) can move the economic-ecological system beyond the extinction threshold. We also show that increasing the pesticide price or decreasing the commercial bee price might lead to reestablishment of wild bees following their local extinction. Thus, we demonstrate the importance of combining ecological modelling with economics to study the provision of ecosystem services and to inform sustainable management of ecosystem service providers.

Ecological aspects of nematode parasites of introduced salmonids from Valdivia river basin, Chile

Between 1986 and 1987 fishes distributed among the following species introduced in Chile, and from different sectors of the Valdivia river basin (39º30' - 40º00', 73º30' - 71º45'W), were examined: 348 Salmo trutta, 242 Salmo gairdneri, 24 Cyprinus carpio and 52 Gambusia affinis holbrooki. The presence of Camallanus corderoi and Contracaecum sp. in S. gairdneri and of C. corderoi in S. trutta is recorded in Chile for the first time. Cyprinus carpio and G. a. holbrooki did not present infections by nematodes. The prevalence and mean intensity of the infections by nematodes presented significant differences among some sectors of the Valdivia river basin. In general, the prevalence and intensity of the infections by C. corderoi were greater than those by Contracaecum sp. The infections in S. gairdneri were higher than in S. trutta. The sex of the hosts had no influence on the prevalence and intensity of the infections by both nematodes. The length of the hosts did have an influence, except in the case of the infections by Contracaecum sp. in S, gairdneri. The infrapopulations of both nematode species showed over dispersion in most cases. The diet of the examined salmonids suggests that they would become infected principally throught the consuption of autochthonous fishes.

Ecological studies on the intermediate host snails and the relevance to schistosomiasis control

A detailed knoledge of distribution patterns schistosome intermediate hsts and their populations dynamics and factors affecting these patterns will provide useful information about the possibilities and desirability of conducting snail control measures in various transmission situations. On the basis of various case studies the association between the occurence of human water contacts and the presence of schistosome intermediate hosts or infections in the intermediate hosts is illustrated. Other parameters affecting snail distribution patterns and density fluctuations are discussed. It is concluded that ecological studies on the intermediate host are extremely relevant, either to optimally apply existing control measures or to develop alternative measures of snail control, such as ecological or biological control.

Deliberative ecological economics: emergence and research issues

We discuss the recent emergence of "deliberative ecological economics", a field that highlights the potential of deliberation for improving environmental governance. We locate the emergence of this literature in the long concern in ecological economics over the policy implications of limited views of human action and its encounter with deliberative democracy scholarship and the model of communicative rationality as an alternative to utilitarianism. Considering criticisms over methods used and the focus of research in deliberative decision-making, we put forward a research agenda for deliberative ecological economics. Given the promising potential of deliberative processes for improving the effectiveness and legitimacy of environmental decision-making, work in this area could help advance both theory and practice in environmental governance.

Studies on the sandfly fauna of Samuel Ecological Station, Porto Velho Municipality, Rondônia State, Brazil

In a study of sandfly species in the Samuel Ecological Station, in Porto Velho, Rondônia State, the following species were identified: Lutzomyia brasiliensis, L. evangelistai, L. gomezi, L. anduzei, L. flaviscutellata, L. richardwardi, L. shawi, L. umbratilis, L. yuilli yuilli, L. dendrophyla, L. puctigeniculata, L. shannoni, L. amazonensis, L. ayrozai, L. carrerai carrerai, L. claustrei, L. davisi and L. lainsoni. L. richardwardi, L. umbratilis and L. c. carrerai were the predominant species captured of man forming 60.30% of the total catch. L. richarwardi was the most frequent at ground level (29.9%), while L. umbratilis predominated in the canopy (48.5%).

Dengue in Brazil - situation, transmission and control: a proposal for ecological control

This article discusses dengue in terms of its conceptual and historical aspects, epidemiological and clinical/pathological nature, and evolution up to the present situation in Brazil. The author discusses the ecological relationship in both the production of dengue and its control. Comparison is made between traditional dengue-control programs and a proposed socially-controlled program of an ecological nature without the use of insecticides. Stress is placed on interdisciplinary technical and scientific activity, broadbased participation by communities in discussing methodological aspects involving them, and prospective evaluation comparing the communities selected for intervention and control communities with regard to clinical and subclinical dengue cases and vector infestation rates in relation to climatic, socio-economic, and behavioural factors.

The snail hosts of schistosomiasis: some evolutionary and ecological perspectives in relation to control

Despite opportunities for radiation provided by spatio-temporal isolation, the basic morphological plan of pulmonate snails has remained conservative. In consequence of the resulting dearth of morphological characters and their plasticity, there is a case for using biochemical characters such as exogenous chemicals released by the snails (e.g. amino acids) and their chemoreception niche as taxonomic aids to classify snails of medical importance. As these same chemicals are used by snails to distinguish conspecifics they could also be used as "environmental antibodies" in controlled release formulations (CRF's) designed to remove target snails in a specific, cost-effective and ecologically acceptable manner. The snails, surface-living bacteria, algae and macrophytic plants are considered as co-evolved, interactive modular systems with strong mutualistic elements. Recently, anthropogenic perturbations such as deforestation, and damming of flowing waters, have benefited these modules whereas others such as river canalization, acid deposition, accumulation of pesticide residues and eutrophication have harmed them. Research is needed to elucidate the factors which limit the growth of snails in primitive habitats, uninfluenced by man, as well as in those subject to harmful anthropogenic factors. The understanding thus gained could be applied to develop cost-effective primary health care strategies to reduce or prevent transmission of schistosomiasis and other water related diseases.