847 resultados para life in Waterville
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Mineral surfaces were important during the emergence of life on Earth because the assembly of the necessary complex biomolecules by random collisions in dilute aqueous solutions is implausible. Most silicate mineral surfaces are hydrophilic and organophobic and unsuitable for catalytic reactions, but some silica-rich surfaces of partly dealuminated feldspars and zeolites are organophilic and potentially catalytic. Weathered alkali feldspar crystals from granitic rocks at Shap, north west England, contain abundant tubular etch pits, typically 0.4–0.6 μm wide, forming an orthogonal honeycomb network in a surface zone 50 μm thick, with 2–3 × 106 intersections per mm2 of crystal surface. Surviving metamorphic rocks demonstrate that granites and acidic surface water were present on the Earth’s surface by ∼3.8 Ga. By analogy with Shap granite, honeycombed feldspar has considerable potential as a natural catalytic surface for the start of biochemical evolution. Biomolecules should have become available by catalysis of amino acids, etc. The honeycomb would have provided access to various mineral inclusions in the feldspar, particularly apatite and oxides, which contain phosphorus and transition metals necessary for energetic life. The organized environment would have protected complex molecules from dispersion into dilute solutions, from hydrolysis, and from UV radiation. Sub-micrometer tubes in the honeycomb might have acted as rudimentary cell walls for proto-organisms, which ultimately evolved a lipid lid giving further shelter from the hostile outside environment. A lid would finally have become a complete cell wall permitting detachment and flotation in primordial “soup.” Etch features on weathered alkali feldspar from Shap match the shape of overlying soil bacteria.
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The fossil record of land plants is an obvious source of information on the dynamics of mass extinctions in the geological past. In conjunction with the end-Permian ecological crisis, ≈250 million years ago, palynological data from East Greenland reveal some unanticipated patterns. We document the significant time lag between terrestrial ecosystem collapse and selective extinction among characteristic Late Permian plants. Furthermore, ecological crisis resulted in an initial increase in plant diversity, instead of a decrease. Paradoxically, these floral patterns correspond to a “dead zone” in the end-Permian faunal record, characterized by a paucity of marine invertebrate megafossils. The time-delayed, end-Permian plant extinctions resemble modeled “extinction debt” responses of multispecies metapopulations to progressive habitat destruction.
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This report aims at understanding how persons aged 50 years and older are and can be integrated into the working society in Belgium. We are interested in how people in this age group can be induced to engage in various forms of employment and lifelong learning. Based on secondary literature, descriptive databases as well as interviews with experts and focus groups, we find that the discussion on active ageing in Belgium is well advanced with numerous contributions by academics, stakeholders, social partners, the public administration and interest groups. The wish to retire at 60 is widely shared, but at the same time the majority of Belgium’s elderly are able and would be willing to work under specific conditions. Therefore, we recommend that Belgium should invest in more flexible systems including a revision of the tax scheme, such as the part-time retirement system proposed by the insurance company Delta Lloyd. An equally relevant recommendation would be to ensure that public employment agencies, employers and agencies that provide training encourage all workers to work and learn regardless of their age.
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This report reviews national and private initiatives to allow the elderly to continue their participation in the Finnish labour market and provides an analysis of the labour market and living conditions of seniors. We are interested in how those over 50 can be engaged in various forms of employment and lifelong learning. We find strong evidence that Finland generally provides good institutional conditions for active ageing. The quick and early ageing process was tackled by the fundamental pension reform that already prolonged retirement substantially and will probably facilitate later retirement as the attitudes concerning retirement change. On the other hand, Finland still seems to lag behind the other Nordic welfare states, has considerable problems in providing the same health conditions to low educated people in physically demanding occupations and could - – with respect to family pension in particular – invest further efforts in reforming the pension system. While many of the reforms Finland has conducted seem to be favourable and transferable to other European countries that still face the steepest phases of ageing in their societies, a reluctance towards changing attitudes that we observe in Finland, shows that organizing active ageing is a long-term project.
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Bibliography: p. 177-181.
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Includes index.
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Mode of access: Internet.
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Mode of access: Internet.