 Thank you very much. Richard Brude asked me to step back a little and reflect a bit on what the term quality of life might mean. So we step back a little from the difficult practical issues we've been dealing with. And I think a little more about the issue of the meaning of this term quality of life. I want to explore with you the concept of quality of life in cities and my own view can be stated very simply that the quality of life in a city is good when its inhabitants are capable of dealing with complexity. And conversely, the quality of life in cities is bad when its inhabitants are capable only of dealing with people like themselves. I don't know if this is useful if I put this in another way to you and this is something we can discuss that a healthy city can embrace and make productive use of the differences of class, ethnicity and lifestyle it contains while a sick city cannot. The sick city isolates and segregates difference drawing no collective strength from its mixture of different people. There are practical consequences that flow from this but I just wanted to say something personal about this. This is an idea that first came to me at the beginning of my career as a young man attending a conference somewhat like this one held in Washington in the late 1960s conference discussing mental health issues among urban poor residents. The conference focused on alienated often violent adolescents at a time when many of these people were rioting in the city. Perhaps because most of the professionals at the conference were psychiatrists they focused on individual psychology. To me it seemed that there was another way to understand the poor quality of life that these young violent adolescents were experiencing. We put it in a very general way that the process of human maturation particularly the passage into adulthood requires that young human beings learn how to deal with situations beyond their personal control and with persons who are strangers to them, strangers who are inter-radically different and difficult to understand. America's racially segregated ghettos offered no such opportunity to learn this nor do isolated ghettos today anywhere in the world. In my own work I've tried to elaborate this insight more largely. All adults in cities need to develop certain skills of living with strangers. These are stranger skills and the question I've asked in my own work is how the design of cities could promote this kind of human competence. You'll sense from this biographical note why I'm not happy with the preoccupation of economists today of equating the quality of life in cities with what are called happiness studies. All academics flourish by creating a field of study. Learning to interact well with strangers requires a toleration of ambiguity. The capacity to contain frustration and ability to listen carefully to people whose speech needs or desires may seem alien. None of these skills falls within the domain of pleasure, if that's what happiness is. Indeed the entry into adulthood occurs exactly when people become capable of feeling connected to and even solidarity with other people who give them no pleasure. And it's I believe for these reasons that instead of focusing on happiness we should stress the concept of social competence as a measure of an adult's quality of life. Because cities are complex social as well as economic and geographic organisms should be in principle a fertile soil for developing social competence. But we know that they are not. The reason for this is that in the development of modern cities we're seeing more and more isolation, segregation and withdrawal of different social groups from one another. The terrain of the city is not allowing people to develop that peculiar competence which adults need to manage a complex environment. Another way to put this is that the modern city has become more and more a homogeneous set of islands divorced from each other. And under these conditions it's difficult for people to develop an ability to manage diversity and competence. I'd say that the consequence is a diminished quality of life in ghetto-wise situations whether those are gated communities or the ghettos of the poor. A city of isolated human islands aborts the experience of difference rendering people less socially competent in dealing with each other. This is why urban designers like myself have focused on the issue of mixture, mixed use, mixture of people putting immigrants for instance together with long-term natives in the city as having not only a practical utility but also having if I can put it this way an ethical utility. The more that we isolate people into familiar neighborhoods into local communities where they have little difference of people unlike themselves, the more we are stunting the growth of both of individuals and diminishing the capacity of people in the city to live together. Now I don't know how this would bear on this attempt of urbanists like myself. It's a kind of holy grail, the notion of social integration for us, for practical and as I say for ethical and personal reasons. How this would bear on the question, the questions we've been dealing with this morning which deal with concrete issues of health. I have to say that the focus on providing local health rings a certain alarm bell for me since it would suggest that the provision of this important biological phenomenon might be at odds with another measure of urban quality which is not local, which is not focused on immediate circumstances but would be more urban in its terrain. So I think that's maybe a point in which we can engage the conversation we've had this morning with the conversation about what makes a healthy city socially and personally. Thank you very much.