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Essential Condition (essential + condition)
Selected AbstractsControlling factors of gullying in the Maracujá Catchment, southeastern BrazilEARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2005L. de A. P. Bacellar Abstract Hundreds of gullies (,voçorocas') of huge dimensions (up to 400,500 m long, 150 m wide and 50 m deep) are very common in the small Maracujá Catchment in southeastern Brazil. These erosional features, which occur with an uneven intensity throughout the area, started due to bad soil management practices at the beginning of European settlement, at the end of the 17th century, and nowadays are still evolving, but at a slower rate. As surface soils are usually very resistant to erosion, the outcrop of the more erodible basement saprolites seems to be an essential condition for their beginning. An analysis of well known erosion controlling factors was performed, aiming to explain the beginning and evolution of these gullies and to understand the reasons for their spatial distribution. Data shows that geology and, mainly, geomorphology are the main controlling factors, since gullies tend to be concentrated in basement rock areas with lower relief (domain 2) of Maracujá Catchment, mainly at the fringes of broad and flat interfluves. At the detailed scale (1:10 000), gullies are more common in amphitheatre-like headwater hollows that frequently represent upper Quaternary gullies (paleogullies), which demonstrate the recurrence of channel erosion. So, gullies occur in areas of thicker saprolites (domain 2), in places with a natural concentration of surface and underground water (hollows). Saprolites of the preserved, non-eroded hollows are usually pressurized (confined aquifer) due to a thick seal of Quaternary clay layer, in a similar configuration to the ones found in hollows of mass movement (mudflow) sites in southeastern Brazil. Therefore, the erosion of the resistant soils by human activities, such as road cuts and trenches (,valos'), or their mobilization by mudflow movements, seem to be likely mechanisms of gullying initiation. Afterwards, gullies evolve by a combination of surface and underground processes, such as wash and tunnel erosion and falls and slumps of gully walls. Copyright © 2005 John Wiley & Sons, Ltd. [source] The Limits of Unilateral Migration Control: Deportation and Inter-state Cooperation1GOVERNMENT AND OPPOSITION, Issue 2 2008Antje Ellermann Despite the recent proliferation of policy initiatives designed to curb illegal immigration, advanced industrialized states have made little headway towards the goal of effective migration control. Examining the case of deportation in Germany and the European Union, this article contends that one of the most fundamental reasons underlying this failure is a unilateral policy bias that fails to take into account two related conditions. First, policies of migration control directly and substantially impinge upon the interests of foreign governments. Secondly, the cooperation of foreign officials is an essential condition for policy implementation. To the extent that they disregard these basic conditions, then, migration control policies are bound to fail. By examining the implementation of deportation policy, the article illustrates the limited efficacy of control measures that are dominated by the interests of advanced industrialized states to the exclusion of the concerns of foreign governments. [source] The role of waves in ice-jam flooding of the Peace-Athabasca DeltaHYDROLOGICAL PROCESSES, Issue 19 2007Spyros Beltaos Abstract Since the late 1960s, a paucity of ice-jam flooding in the lower Peace River has resulted in prolonged dry periods and considerable reduction in the area covered by lakes and ponds that provide habitat for aquatic life in the Peace-Athabasca Delta (PAD) region. To identify the causes of this trend, and to develop mitigation or adaptation strategies under present and future climatic conditions, it is necessary to understand the mechanisms that lead to breakup of the ice cover and jamming within the delta reach of Peace River. Because the lower Peace is extremely flat, the long-period waves caused by spring snowmelt are not generally capable of dislodging the winter ice cover, even under conditions of very high flow. The ice cover decays in place and rubble generation, an essential condition for ice jamming, does not occur. However, major jams do, on occasion, form in the middle section of the river and make their way to the delta via repeated releases and stalls. Each release generates a steep wave which can greatly amplify the hydrodynamic forces that are applied on the ice cover and bring about its dislodgment. This is quantified for the lower Peace River by applying recently developed methodology to local hydrometric data. Detailed in situ observations in the spring of 2003, and additional data from 1997 and 2002, fully corroborate this conclusion. Implications to other flat rivers of northern Canada are discussed. Copyright © 2007 Crown in the right of Canada. Published by John Wiley & Sons, Ltd. [source] Chromogenic polymer gels for reversible transparency and color control with temperature at a constant volumePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7 2002A. Seeboth Abstract The preparation and characterization of novel chromogenic materials has developed extremely rapid in the last years. Among them, thermotropic and thermochromic polymer gel networks have met with growing interest, because of their advanced properties. These novel polymer gels exhibit pronounced changes in transparency and/or color intensity in a practically relevant temperature range. For many future technical applications it is an essential condition, that the volume of the used gel materials is independent of temperature. A current overview of this field is given. Copyright © 2002 John Wiley & Sons, Ltd. [source] Exercising power in a prisoner's dilemma: transnational collective bargaining in an era of corporate globalisation?INDUSTRIAL RELATIONS JOURNAL, Issue 4 2005William N. CookeArticle first published online: 21 JUN 200 ABSTRACT The extraordinary growth in foreign direct investment coupled with the widespread declination of union penetration has increasingly allowed multinationals to pit unions across borders as competitors for investment and jobs. Based on a theoretical analysis of the exercise of power in a prisoner's dilemma game, the essential conditions and incentives for cooperation among unions across borders for the purpose of collective bargaining with multinationals are identified and practical, strategic-level implications for transnational interunion partnerships are addressed. [source] RECENT DEVELOPMENTS IN GERMAN CAPITAL MARKETS AND CORPORATE GOVERNANCEJOURNAL OF APPLIED CORPORATE FINANCE, Issue 3 2001Eric Nowak Financial economists continue to point to Germany as a relatively successful model of a "bank-centered," as opposed to a market-based, economy. But few seem to recognize that, in the years leading up to World War I, German equity capital markets were among the most highly developed in the world. Although there are now only about 750 companies listed on German stock exchanges, in 1914 there were almost 1,200 (as compared to only about 600 stocks then listed on the New York Stock Exchange). Since German reunification in 1990, there have been signs of a possible restoration of the country's equity markets to something like their former prominence. The last 10 years have seen important legal and institutional developments that can be seen as preparing the way for larger and more active German equity markets, together with a more "shareholder-friendly" corporate governance system. In particular, the 1994 Securities Act, the Corporation Control and Transparency Act passed in 1998, and the just released Takeover Act and Fourth Financial Market Promotion Act all contain legal reforms that are essential conditions for well functioning equity markets. Such legal and regulatory changes have helped lay the groundwork for more visible and dramatic milestones, such as the Deutsche Telekom IPO in 1996, the opening of the Neuer Market in 1997, and, perhaps most important, the acquisition in 2000 of Mannesmann by Vodafone, the first successful hostile takeover of a German company. [source] ZnO nanowire arrays , Pattern generation, growth and applicationsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2010Margit Zacharias Abstract ZnO nanowires and related materials are in the focus of attention for electronic, optical or sensor applications. However, size, position and arrangement control are essential conditions for the development of future nanowire based devices. Various kinds of template methods including nanosphere lithography and UV laser interference lithography are powerful tools for the preparation of the starting metal catalyst arrays and will be demonstrated and discussed. However, only if the growth mechanism and its guiding parameters are understood in detail, the template will force a pattern arranged growth of nanowires. The paper gives an overview of the various kinds of growth modes for vertical arranged nanowires. Specific experimental conditions establishing the VS or the VLS growth are discussed. In addition, insight is given why the patterning is not all the time conserved and how to overcome these obstacles. In the second part different kinds of applications are summarized. Electronic properties are discussed based on metal,semiconductor,metal devices. The influence of a core,shell nanowire structure on the optical properties is demonstrated. In addition, a simple approach for ZnO nanowire based gas sensors is discussed and shown. As a last example, the transfer of Al2O3 coated nanowires into spinel tubes is reported. [source] | ||||||||||