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Many possible answers have been suggested for this puzzle : busy-ness and time pressure ; economic hard times ( or , according to alternative theories , material affluence ) ; residential mobility ; suburbanization ; the movement of women into the paid labor force and the stresses of two-career families ; disruption of marriage and family ties ; changes in the structure of the American economy , such as the rise of chain stores , branch firms , and the service sector ; the sixties ( most of which actually happened in the seventies ) ; including Vietnam , Watergate , and disillusion with public life ; and the cultural revolt against authority ( sex , drugs , and so on ) ; growth of the welfare state ; the civil rights revolution ; television , the electronic revolution , and other technological changes . Dr. Merklein was the first to investigate microstructural changes in the structure of aluminium alloys that arise as a result of such heating . It is clear from the studies reviewed here that small changes in the structure of sphingolipids alter their partitioning between lateral domains substantially . Pursuit of professionalism is leading to remarkable changes in the structure of the military . These processes often involve changes in the structures of the viral proteins , and our goal is to determine their conformations at the various stages of an infection . These developments were made possible by two important changes in the structure of the medical school . There was no overall change in the structure of the businesses ; they both used one address and had the same employees . The change in the structure of production explains this fact since during 1976 the wholesale price was 691 millimes per kg whereas the cost price ( not including profit margin and transport costs ) varied according to the type of farming between 583 millimes and 791 millimes . The Task Force on the Future of the Canadian Financial Services Sector established in December 1996 has not yet completed its consultation process and analysis and , therefore , we are not prepared to allow such a fundamental change in the structure of the financial sector . The change in the structure of production has also been dramatic .