3 resultados para global changes

em Repositório Científico da Universidade de Évora - Portugal


Relevância:

60.00% 60.00%

Publicador:

Resumo:

Portugal is characterized by a significant asymmetry in the population distribution/density and economic activity as well as in social and cultural dynamics. This means very diverse landscapes, differences in regional development, sustainability and quality of life, mainly between urban and rural areas. A consequence coherent with the contemporary dynamics: urbanization of many rural areas that loose their productive-agricultural identity and, simultaneously, the reintegration in urban areas of spaces and activities with more rural characteristics. In this process of increasing complexity of organization of the landscape is essential to restore the continuum naturale (between urban and rural areas) allowing closer links to both ways of life. A strategy supported in the landscape, which plays important functions for public interest, in the cultural, social, ecological and environmental fields. At the same time, constitutes an important resource for economic activity, as underlined in the European Landscape Convention. Based on this assumption, and using a multi-method approach, the study aims to analyse a) the links between urban and rural areas in Portugal and b) the reasons why these territories are chosen by individuals as places of work and mobility, residence or evasion, culture and leisure, tranquillity or excitement â meaning overall well-being. Primary information was obtained by a questionnaire survey applied to a convenience sample of the Portuguese population. Secondary data and information will be collected on the official Portuguese Statistics (INE and PORDATA). Understanding the urban-rural links is essential to support policy measures, take advantage from the global changes and challenge many of the existing myths.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

A climate study of the incidence of downward surface global solar radiation (SSRD) in the Iberian Peninsula (IP) based primarily on ERA-40 reanalysis is presented. NCEP/NCAR reanalysis and ground-based records from several Portuguese and Spanish stations have been also considered. The results showthat reanalysis can capture a similar inter-annual variability as compared to ground-based observations, especially on a monthly basis, even though annual ERA-40 (NCEP/NCAR) values tend to underestimate (overestimate) the observations with a mean relative difference of around 20Wmâ2 (40Wmâ2). On the other hand, ground-based measurements in Portuguese stations during the period 1964â1989 show a tendency to decrease until the mid-1970s followed by an increase up to the end of the study period, in line with the dimming/brightening phenomenon reported in the literature. Nevertheless, there are different temporal behaviours as a greater increase since the 1970s is observed in the south and less industrialized regions. Similarly, the ERA-40 reanalysis shows a noticeable decrease until the early 1970s followed by a slight increase up to the end of the 1990s, suggesting a dimming/brightening transition around the early 1970s, earlier in the south and centre and later in the north of the IP. Although there are slight differences in the magnitude of the trends as well as the turning year of the dimming/brightening periods, the decadal changes of ERA-40 fairly agree with the ground-based observations in Portugal and Spain, in contrast to most of the literature for other regions of the world, and is used in the climatology of the SSRD in the study area. NCEP/NCAR reanalysis does not capture the decadal variations of SSRD in the IP. The results show that part of the decadal variability of the global radiation in the IP is related to changes in cloud cover (represented in ERA-40).

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Soil salinity affects rhizobia both as free-living bacteria and in symbiosis with the host. The aim of this study was to examine the transcriptional response of the Lotus microsymbiont Mesorhizobium loti MAFF303099 to salt shock. Changes in the transcriptome of bacterial cells subjected to a salt shock of 10% NaCl for 30 min were analyzed. From a total of 7231 protein-coding genes, 385 were found to be differentially expressed upon salt shock, among which 272 were overexpressed. Although a large number of overexpressed genes encode hypothetical proteins, the two most frequently represented COG categories are "defense mechanisms" and "nucleotide transport and metabolism". A significant number of transcriptional regulators and ABC transporters genes were upregulated. Chemotaxis and motility genes were not differentially expressed. Moreover, most genes previously reported to be involved in salt tolerance were not differentially expressed. The transcriptional response to salt shock of a rhizobium with low ability to grow under salinity conditions, but enduring a salinity shock, may enlighten us concerning salinity stress response mechanisms.