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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Algebra universalis 28 (1991), S. 188-213 
    ISSN: 1420-8911
    Keywords: co-rectangular-band object in a category of algebras ; decomposition of an algebra as a coproduct ; sheaf or cosheaf of algebras on a Stone space ; bounded Boolean power of an object of a category ; Primary: 08B25 ; 18D35 ; 18F20 ; 20M17 ; secondary: 06E15 ; 18A30 ; 20M50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Conditions on a categoryC are studied which imply that every structure of rectangular band on an objectS ofC arises from a unique product decompositionS=S 1×S 2, especially in the case whereC is the opposite of a category of algebras. Sheaves on Stone spaces with values in opposites of categories of algebras are examined. The analog of the bounded Boolean power constructionR[B]* forR an object of a general category is described.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Algebra universalis 28 (1991), S. 153-187 
    ISSN: 1420-8911
    Keywords: action of a Boolean ring on a set, sheaf of sets on the spectrum of a Boolean ring, commuting rectangular band operations ; bounded Boolean power of a set or algebra ; least nontrivial hypervariety of algebras ; Primary: 06E15 ; 06E20 ; 18F20 ; secondary: 08A05 ; 08B25 ; 18C10 ; 20M50 ; 54H10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract LetB be a Boolean ring (with 1),S a sheaf of sets on the Stone space Spec(B), andS the set of global sections of S. For everya εB ands, t εS, leta(s, t) denote the element ofS which agrees withs on the support ofa, and witht elsewhere. We set down identities satisfied by this ternary operationB×S×S→S (involving also the Boolean operations ofB). For a fixed Boolean ringB, we call a setS given with a ternary operation satisfying these identities aBset. The above construction is shown to give a functorial equivalence between sheaves of setsS on Spec(B) with nonempty sets of global sections, and nonemptyB-setsS. For any setA, the bounded Boolean powerA[B]* is the freeB-set onA. The varieties ofB-sets, asB ranges over all Boolean rings, constitute (together with one trivial variety) the least nontrivial hypervariety of algebras, in the sense of W. Taylor.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Transportation 22 (1995), S. 295-323 
    ISSN: 1572-9435
    Keywords: densities ; development ; environment ; externalities ; land-use ; planning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract There are clear signs of a shift in the UK transport policy in response to concerns about the environmental impacts of road transport and anxieties about the implications of the projected future growth in demand. Much of the framework of UK transport policy is now determined at the overall European Union level. To date most European legislation and policy proposals have been concerned with reducing the specific externalities associated with the transport sector, with none of the measures involved likely to have more than a marginal impact on the growth in demand. The emerging research evidence suggests however that the private costs of car use in Europe may fall substantially short of its total social costs and there is an important emerging policy debate about how this gap might be closed. The UK has introduced a policy package designed to reduce the growth of car travel and its environmental impact, within which land-use planning measures feature prominently. The land-use policies, which to some extent represent a reassertion of many traditional UK planning policies, include: an emphasis on focussing new development in urban areas, increasing residential densities, strengthening the role of existing centres and improving provision for walking and cycling. A number of factors will constrain the effectiveness of the package in practice. There are also concerns about its impact on key environmental objectives, including air quality. There are important questions too about the welfare effects of increasing densities and about the wider impacts of the package on economic efficiency.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of assisted reproduction and genetics 15 (1998), S. 594-598 
    ISSN: 1573-7330
    Keywords: blastocyst ; development ; fertilization ; intracytoplasmic sperm injection ; in vitro fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: To examine the blastocyst formation rates of day-2 fertilized oocytes. Methods: A retrospective study of the outcomes/blastocyst formation of day-2 fertilized oocytes was undertaken. Results: Fertilization rates of day-1 and -2 oocytes by intracytoplasmic sperm injection were similar. The development frequencies to four cells were similar. However, the blastulation rates were significantly lower from the day-2 fertilized eggs. The fertilization rates from day-2 conventional in vitro fertilization reinsemination were lower than the fertilization rates of day-1 oocytes. The blastulation rates from day-2 fertilized eggs were also lower than the rates from day-1 fertilized eggs in the in vitro fertilization group. Conclusions: Fertilization is not a good indicator to predict the viability of fertilized oocytes. Day-2 fertilized oocytes had significantly lower blastocyst formation rates than the rates from day-1 fertilized oocytes.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of assisted reproduction and genetics 11 (1994), S. 303-307 
    ISSN: 1573-7330
    Keywords: mouse ; embryo ; culture medium ; development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose Our purpose was to find a medium to enhance mouse zygote development and, hopefully, to apply the results to a coculture system and to enhance the ART pregnancy rate. Design The study was designed to compare different media's support of mouse zygote development with/without serum supplement. The outcome measure was the percentage of mouse zygotes/embryos that developed to the expanded blastocyst and hatchout stage. Results (1) Using human tubal fluid (HTF), one-cell zygotes had a 34.6±5.2% (mean±standard deviation) development rate, and two-cell embryos a 86.5±3.2% development rate. (2) Minimum essential medium alpha (MEM) showed the best results (52.2±14.5%) among Ham's F-10 (19.1±6.3%), HTF (26.8±8.2%), NCTC-135 (38.8±12.6%), MEM with nuclei acid (24.6±10.0%), and Dulbecco's modified Eagle medium (28.0±20.2%). (3) With the serum supplement, there was no significant difference among Ham's F-10 (21.5±23.7), HTF (29.3±10.4%), NCTC-135 (36.5±6.2%), and MEM (38.8±17.9%). Conclusion MEM is the best medium among the six media examined. Preliminary study showed that MEM gave a good clinical pregnancy rate (29%).
    Type of Medium: Electronic Resource
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