Browsing by Issue Date, starting with "2009-10"
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- Retinopatia pimentarPublication . Almeida , Andreia Patrícia Lourenço de; Leite, Eugénio Óscar Luiz BatistaRetinopatia Pigmentar é um termo que descreve um amplo grupo de retinopatias de tipo hereditário muito heterogéneo tanto a nível genético como clínico. A Retinopatia pigmentar tem uma prevalência de cerca de 1,5 milhões de pessoas no mundo e a sua incidência é de aproximadamente 1 por cada 4000. É a principal causa de cegueira em indivíduos adultos e não tem cura até à data. O primeiro sintoma que os infectados apresentam é uma nictalopia (cegueira nocturna) desde muito cedo e pode ser o único durante vários anos. Num estado mais avançado perde-se progressivamente a visão periférica (redução do campo visual) devido à degeneração dos bastonetes e em certos casos até à perda total da visão. Os tipos de retinopatia pigmentar hereditária classificam-se em várias categorias e têm prevalências sensivelmente diferentes para os vários autores.
- WLAN planning tool: a techno-economic perspectivePublication . Sebastião, Pedro; Tomé, Ricardo; Velez, Fernando J.; Grilo, António; Cercas, Francisco; Robalo, Daniel; Rodrigues, António; Varela, Frederico F.A simple wireless local area network (WLAN) planning tool was developed to optimize the position and number of access points (APs), as well as the total cost of the required equipment, according to different WLAN suppliers, in indoor and outdoor environments. This planning tool can be distinguished in two mains scopes: technical (defining the number and position of APs) and economic (generating a budget according to all planned equipment and its suppliers). The proposed planning tool enables manual and automatic planning modes. It only needs some inputs, like the digital format of the floor plan, the obstacle types and their positions, the areas to be covered, the user’s most probable position and the applications used by them. The propagation model used in this tool was validated using experimental results for some scenarios. In the manual mode, the APs positions are defined by the network designer. The output of the tool is the received power or the throughput, depending on the chosen option. However, in the automatic mode the tool defines the AP position and minimizes the total amount of APs in a given area. For the implementation of the latter mode, two hot spots position planning algorithms were developed and implemented; they depend on the values of the received power or throughput, while guaranteeing the total coverage or service supply for all users, respectively. This tool also provides an estimation of the budget for the required implementation, and can avoid several days of tedious site-survey work. Except for the lowest distances, experimental values for the received power generally agree with the DP model for the range of distances considered, from the terminal station to the AP, both for outdoor and indoor environments. The differences near the AP are due to different antenna radiation patterns between the tool (omnidirectional isotropic) and the experimental setup (dipole antenna). In the indoor paths, the slight differences between the results of two floors may be due to the interaction of the direct ray with the floor direction itself.
- Development of a new chitosan hydrogel for wound dressingPublication . Ribeiro, MP.; Espiga, Ana; Silva, Daniela; Baptista, Patrícia; Henriques, Joaquim; Ferreira, Catarina L.; Silva, Jorge; Borges, João; Pires, Eduardo; Chaves, Paula; Correia, Ilídio Joaquim SobreiraWound healing is a complex process involving an integrated response by many different cell types and growth factors in order to achieve rapid restoration of skin architecture and function. The present study evaluated the applicability of a chitosan hydrogel (CH) as a wound dressing. Scanning electron microscopy analysis was used to characterize CH morphology. Fibroblast cells isolated from rat skin were used to assess the cytotoxicity of the hydrogel. CH was able to promote cell adhesion and proliferation. Cell viability studies showed that the hydrogel and its degradation by-products are noncytotoxic. The evaluation of the applicability of CH in the treatment of dermal burns in Wistar rats was performed by induction of full-thickness transcutaneous dermal wounds. Wound healing was monitored through macroscopic and histological analysis. From macroscopic analysis, the wound beds of the animals treated with CH were considerably smaller than those of the controls. Histological analysis revealed lack of a reactive or a granulomatous inflammatory reaction in skin lesions with CH and the absence of pathological abnormalities in the organs obtained by necropsy, which supported the local and systemic histocompatibility of the biomaterial. The present results suggest that this biomaterial may aid the re-establishment of skin architecture.