Homeostasis of continuously renewing tissues, such as the epidermis, is maintained by somatic undifferentiated, self-renewing stem cells, which are thought to persist throughout life. Through a series of labeling experiments, we previously showed that stem cells from mouse skin did not divide often, but they did divide at a steady rate in vivo. Using our recently redefined sorting method, we isolated epidermal stem and transit amplifying (TA) cells from mouse skin. When injected into a developing blastocyst or into damaged tissues, the stem cells, but not the TA cells, could participate in the formation of new tissues. We hypothesize that all tissues contain reserved undifferentiated stem cells that are primed to react if needed. These reserve stem cells could restore the tissue in which they reside or they could be called upon to help restore another tissue that was severely damage.
Water is a scarce resource and must be efficiently managed. One of the purposes of efficient management should be reducing water losses and increasing supply performance in the networks through a profound knowledge of water supply networks (WSN). Obtaining this knowledge in real networks is a complex task because distribution systems may consist of thousands of consumption nodes interconnected by thousands of lines and the necessary elements to feed the network. These networks are not usually the outcome of a single process of design and are the consequence of years of anarchic responses to continually rising new demands. As a result, layouts lack a clear structure from a topological point of view.The division of a water supply network into supply clusters enables sufficient hydraulic knowledge to be gathered to carry out maintenance tasks and guarantee quantity and regularity to the final consumer. This approach divides large and highly interconnected distribution networks into smaller sub-networks. These smaller networks are virtually independent and fed by a prefixed number of sources. Independence can be physically enforced in a number of ways. For instance, by closing valves in existing pipes, by sectioning existing pipes, or by introducing new pipes to redistribute the flow. Each supply cluster inlet must be equipped with at least one flowmeter to accurately measure and record consumption in short time periods.However, gauges and meters must also be placed to measure and control pressure, chlorine concentrations, and other supply parameters.Water network division into supply clusters should not be understood only in network configuration terms, but also as a permanent method of management. It is essential to provide the system with a main centre that can receive and sort daily data, as well as analyse other information (such as financial, climatological, inventory, and maintenance data). In this way, we can establish the real performance of sectors and take appropriate decisions regarding both operational maintenance and investment. From a classical perspective, the division of a water supply network into sectors is used with the aim of controlling leaks, since it helps maintain a permanent pressure control system. Nevertheless, this target has recently become more ambitious and incorporates new operational and management tasks.This thesis proposes a suitable framework to establish efficient methods to divide the network into sectors and manage a WSN by taking advantage of this structure. These tasks will be addressed using kernel methods and multi-agent systems. Spectral clustering and semi-supervised learning have been shown to behave well when defining a sectorised network with a minimum number of cut-off valves. However, their algorithms are slow (and sometimes infeasible) when tackling divisions in a large WSN. The multi-agent system approach, firstly created as an alternative solution, is an excellent complementary tool for clustering kernel methods that use a boosting methodology. It is ther...
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