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  • 1
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 39 (1998), S. 3530-3546 
    ISSN: 1089-7658
    Quelle: AIP Digital Archive
    Thema: Mathematik , Physik
    Notizen: It is known that in the Wentzel–Kramers–Brillouin approximation of multicomponent systems like the Dirac equation or Born–Oppenheimer approximation, an additional phase appears apart from the Berry phase. So far, this phase was only examined in special cases, or under certain restrictive assumptions, namely, that the eigenspaces of the matrix or endomorphism valued symbol of the Hamiltonian form trivial bundles. We give a completely global derivation of this phase which does not depend on any choice of local trivializing sections. This is achieved using a star product approach to quantization. Furthermore, we give a systematic and global approach to a reduction of the problem to a problem defined completely on the different "polarizations." Finally, we discuss to what extent it is actually possible to reduce the problem to a really scalar one, and make some comments on obstructions to the existence of global quasiclassical states. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 792 (1996), S. 0 
    ISSN: 1749-6632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 1 (1999), S. 347-376 
    ISSN: 1523-9829
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Technik allgemein , Medizin
    Notizen: Abstract The continuing accrual of positive results in clinical cancer trials of adjunctive, synergistic hyperthermia therapy remains a strong motivation for the development of improved hyperthermia equipment and software. Indeed, the lack of needed engineering tools can be viewed as the major stumbling block to hyperthermia's effective clinical implementation. Developing clinically effective systems will be difficult, however, because (a) it requires solving several complex engineering problems, for which (b) setting appropriate design and evaluation goals is currently difficult owing to a lack of critical biological, physiological, and clinical knowledge, two tasks which must (c) be accomplished within a complicated social/political structure.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Economics & politics 7 (1995), S. 0 
    ISSN: 1468-0343
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Politikwissenschaft
    Notizen: A model of elections is put forth in which there are two parties, each representing a different constituency of voters (the poor and the rich). The political issue is the choice of a proportional tax rate on income, revenues from which are used to finance a public good. There is a stochastic element in which party wins the elections, due to party uncertainty concerning voter preferences, or due to uncertainty concerning which voters will show up at the polls. A political equilibrium in one period consists in a tax policy put forth by each party, and a probability that each party wins. A long series of elections is simulated (100 periods). Voter preferences for the public good change adversely as a function of length of time the incumbent party has been in power and the level of the public good in the last period. Thus, if the party in power funds high levels of the public good, preferences start to move against the public good. This model generates dramatic political cycles, and it is argued that these cycles are of fundamentally different origin from that discussed in the realignment literature.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 115 (1996), S. 0 
    ISSN: 1439-0523
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: In a field experiment with topless faba beans, parental inbred lines and FI hybrids of a 7 × 7-diallel were evaluated for traits related to the P, N and K efficiency. In addition, the parental inbreds were cultivated in a pot experiment at two P levels (100 vs. 700 mg P per pot). Significant heterosis for grain yield, uptake and utilization efficiency of nutrients in the field experiment highlighted the enhancement of nutrient efficiency in the hybrids. Amongst both parental inbreds and hybrids, significant genotypic variation was found for nearly all recorded traits. In the diallel analysis, the GCA effects generally proved to be highly significant and in most cases considerably higher than the SCA effects. In the pot experiment, grain yield ranking of the parental lines at the high P level (= P700) was very similar to that in the field experiment, whereas at the low P level (= P100, – P deficiency) the ranking of the lines changed considerably. Correspondingly, the P level-line interaction was highly significant. High tolerance towards P deficiency was found for those two parental inbreds derived from cultivars bred under Syrian conditions. At the high P supply, P efficiency was more favoured by a high P uptake, but at P deficiency by a high internal P utilization.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Oxford BSL : Blackwell Science Ltd
    Clinical & experimental allergy 28 (1998), S. 0 
    ISSN: 1365-2222
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Living in a damp home has been associated with impaired respiratory health in previous studies, but objective data on lung function variability and atopy have been lacking from most studies.〈section xml:id="abs1-2"〉〈title type="main"〉ObjectivesData collected in the winter of 1993–1994 in the framework of the PEACE study (Pollution Effects on Asthmatic Children in Europe) were used to study the association between home dampness and Peak Flow (PEF) variability, frequency of respiratory symptoms and relief medication use during the period of observation.〈section xml:id="abs1-3"〉〈title type="main"〉MethodsChildren were selected with a screening questionnaire on the basis of positive answers to questions on symptoms of asthma and chronic cough. Children were instructed to perform PEF measurements with Miniwright PEF meters twice daily over a period of 2 months. Parents kept diaries on respiratory symptoms and medication use of their children. Data on demographic and housing characteristics were derived from a parent-administered questionnaire. As indicators for home dampness reported moisture stains and moulds were used. Children were tested for atopy with skin-prick tests. Data from 1614 children from 13 centres in 10 different countries were available for analysis. Linear regression models and prevalence rate ratios were used to investigate the association between home dampness and PEF variability and the period prevalence of cough, phlegm, lower and upper respiratory symptoms and bronchodilator use.〈section xml:id="abs1-4"〉〈title type="main"〉ResultsIn atopic children, PEF variability was positively related to self-reported moulds but not to moisture stains. The period prevalence of cough and upper respiratory symptoms was significantly higher in children living in houses with reported moulds, compared with ‘dry’ homes.〈section xml:id="abs1-5"〉〈title type="main"〉ConclusionsThese results show that self-reported moulds in homes are associated with objective as well as subjective markers of airway lability in European children with chronic respiratory symptoms.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 48 (1996), S. 0 
    ISSN: 1095-8649
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Environmental sex determination by temperature could be revealed significantly in 33 Apistogramma-species and in Poecilia melanogaster. In some, but not all, Apistogramma-species pH also influences the sex ratio, whereas neither temperature nor pH affect the sex ratio of Pseudocrenilabrus multicolor victoriae. The sex in offspring of A. trifasciata is determined within a sensitive period of about 30 to at least 40 days after spawning.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 182 (1998), S. 595-607 
    ISSN: 1432-1351
    Schlagwort(e): Key words Behaviour ; Sensory coding ; Sound intensity difference ; Insect ; Bushcricket
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The ability of the female bushcricket, Requena verticalis, to discriminate between two conspecific sound signals that differed in sound pressure level (SPL) was tested in a two-choice paradigm. Significant discrimination was achieved with a 2-dB difference. The property of each pair of receptors to establish binaural discharge differences was investigated in electrophysiological experiments. The threshold to the conspecific signal varies for each fibre from about 40 to 90 dB SPL, allowing for a range fractionation of the hearing organ. Each pair of receptors establishes significant binaural discharge differences only within a restricted intensity range about 10 dB above threshold. Based on a model of the intensity response function of a receptor the total discharge of the 22 receptors in both ears was calculated with monaural and binaural stimulation. The profile of receptors exhibiting significant discharge differences changes with increasing SPL, from the most sensitive fibres with a characteristic frequency between 12 kHz and 35 kHz at low SPLs to the least sensitive fibres at very low and high characteristic frequencies at medium to high SPLs. The discharge difference with an intensity difference of 2 dB is rather small (4% of the total receptor activity) and limited only to a few pairs of receptors.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] O'Neill et al. propose that epigenetic pro-cesses help to drive karyotypic evolution in marsupials. Here we present evidence that global methylation patterns do not undergo dramatic changes in interspecific hybrids among three orders of placental mammals, indicating that the mechanisms ...
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    [s.l.] : Macmillan Magazines Ltd.
    Nature 394 (1998), S. 773-776 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Ears of modern insects occur on a wide variety of body parts and are thought to have evolved from ubiquitous stretch or vibration receptors. This relationship, based on comparative anatomy and similarities in the embryological development of ears in divergent taxa, has led to the widespread ...
    Materialart: Digitale Medien
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