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  • 1
    Electronic Resource
    Electronic Resource
    A dynamic specification of an AIDS import allocation model (1993)
    Springer
    Empirical economics 18 (1993), S. 57-73 
    Details
    ISSN: 1435-8921
    Keywords: C12 ; C32 ; C52 ; F14
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract In this paper we use the first-order autoregressive scheme in order to introduce dynamics into the AIDS model. We also consider the theoretical restrictions of additivity, homogeneity and symmetry, and use two different specifications of the covariance matrix. We estimate the models using import allocation data for the UK 1952–1979 of five EEC countries and test different specifications against each other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01238879
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  • 2
    Electronic Resource
    Electronic Resource
    Spreading of risk and stabilization of animal numbers (1968)
    Springer
    Acta biotheoretica 18 (1968), S. 165-194 
    Details
    ISSN: 1572-8358
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01556726
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  • 3
    Electronic Resource
    Electronic Resource
    Temperatur, Luftfeuchtigkeit und Fortpflanzung bei Mäusen (1970)
    Springer
    International journal of biometeorology 14 (1970), S. 85-93 
    Details
    ISSN: 1432-1254
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung 73 geschlechtsreife Mäuse des SEA- und CBA-Stammes wurden bei 36°C und 43–53% RF oder 83–100% RF sowie 22,5°C, 62–67% RF für 10 Tage (männliche Tiere) und 15 Tage (weibliche Tiere) gehalten. Die Resultate zeigten, dass sich hohe RF weniger negativ auf Körpergewichtsentwicklung und das Gewicht der Sexualorgane (gesamter Geschlechtstrakt) und Hoden auswirkten als niedrige RF. Als Erklärung wird angenommen, dass niedrige RF vor allem eine grössere Belastung des Organismus hervorruft die ihrerseits über die Respiration das Elektrolytgleichgewicht sowie über das endokrine System zur Wirkung gelangte.
    Abstract: Resume On a placé 73 souris complétement développées des races SEA et CBA dans trois atmosphères différentes: 35°C et 43 à 53% d'humidité relative, 36°C et 83 à 100%, 22,5°C et 62 à 67%. Les mâles y ont séjourné 10 jours, les femelles 15. Les résultats obtenus montrent qu'un haut degré d'humidité a de moins graves conséquences sur le poids du corps et des organes génitaux ainsi que sur la production de spermatozoïdes que de faibles humidités relatives. On admet, pour expliquer ces constatations, que de faibles humidités provoquent une contrainte plus marquée de l'organisme tout entier. Cette contrainte serait le résultat de modifications respiratoires, du bilan électrolytique et des fonctions endocrines.
    Notes: Abstract 73 mature mice of the SEA und CBA-strains were kept at 36°C, 43–53% RH or 83–100% RH and 22.5°C, 62–67% RH for 10 days (males) and 15 days (females). The results showed that high RH conditions decreased body and sexual organ weight (female and male genital tract) and inhibited spermatogenesis to a lesser degree than high ambient RH. This was assumed to be the result of a more pronounced stress on the whole organism due to changes in respiration, electrolyte balance, and endocrine functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01440679
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  • 4
    Electronic Resource
    Electronic Resource
    Simulation experiments illustrating stabilization of animal numbers by spreading of risk (1970)
    Springer
    Oecologia 5 (1970), S. 240-284 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. This paper discusses results of simulation studies with population models that were set up to illustrate the ideas about stabilization of population fluctuations and spreading of the risk of extinction expounded by den Boer (1968). In particular, the number of factors influencing net reproduction, the heterogeneity of the habitat and the possibility of a population's containing animals of different age classes were considered as possibly contributing to stabilization and to spreading of risk. 2. The model defined by equation (3.1.2), where r(t) denotes the net reproduction from t to t+1, f i (t) denotes the value of the i-th environmental factor in year t, and where the other symbols denote positive constants, was simulated by choosing for the f i(t) sequences of meteorological data from published tables. Such sequences may be serially correlated as well as correlated among themselves and using such real data was considered to be more realistic than working with sequences of independent random numbers, for example. Increasing the number k of factors turned out to stabilize fluctuations in the density. This fact could also be mathematically proved under not very restrictive assumptions. In a model where the logarithm of the net reproduction on the average is some-what greater than zero, and where “crashes” may occur at high densities, the population may persist for a very long time, even if the “size” of the crashes does not depend on density, and the times at which the crashes occur are chosen at random. 3. A model formulated in terms of matrices and vectors, in which a population was supposed to consist of 9 subpopulations and of several age classes was simulated. It was assumed that after a reproduction period the animals migrate between the subpopulations or emigrate from the whole population. It turned out that increasing the number of age classes may increase stability and that models where there is exchange of individuals between subpopulations by \ldmigration\rd are more stable than populations consisting of isolated subpopulations. Letting the exchange between subpopulations be \lddensity-dependent\rd had some stabilizing effect too, but not very conspicuously so.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344886
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  • 5
    Electronic Resource
    Electronic Resource
    Density dependence and the stabilization of animal numbers (1986)
    Springer
    Oecologia 69 (1986), S. 507-512 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The claim of Varley and Gradwell that the highly density-dependent pupal predation (k 5) in the population of the winter moth in Wytham Wood, England would keep density within limits (regulate) is compared in this paper with the density limits in the null model: pupal predation causes the same mean generation mortality (35%) as in the field, but is not density-dependent, i.e. either constant or randomly fluctuating between years according to the actual frequency distribution, ceteris paribus. According to this null model the winter moth would have fluctuated between narrower limits than in the field; the claim of Varley & Gradwell must thus be rejected. It is more generally concluded that a regulating factor should be the key factor, but this is not a sufficient condition. It should also prevent in some way the low throughs in the time series that usually accompany the operation of a dominating density-dependent mortality factor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410355
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  • 6
    Electronic Resource
    Electronic Resource
    Boekbesprekingen - Reviews (1985)
    Springer
    De economist 133 (1985), S. 232-256 
    Details
    ISSN: 1572-9982
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01676410
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  • 7
    Electronic Resource
    Electronic Resource
    A change in the phosphorylation pattern of the 30000–33000 M r synaptonemal complex proteins of the rat between early and mid-pachytene (1995)
    Springer
    Chromosoma 104 (1995), S. 154-163 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The lateral elements (LEs) of synaptonemal complexes (SCs) of the rat contain major components with relative electrophoretic mobilities (M r s) of 30000–33000, which are the products of a single gene. After one-dimensional separation of SC proteins on polyacrylamide-SDS gels, these components show up as two major bands, whereas upon two-dimensional electrophoresis they are resolved in at least 24 spots, which focus at pH 6.5 to 9.5. In this paper we show that these spots represent phosphorylation variants. For the analysis of the phosphorylation of the 30000- to 33000-M r SC components during progression through meiotic prophase, we developed a procedure for isolation of fractions of testicular cells of the rat that are enriched in separate stages of meiotic prophase. Analysis of the 30000- to 33000-M r SC components in these fractions by two-dimensional electrophoresis and immunoblotting showed that phosphorylated variants of the 30000- to 33000-M r SC proteins occur throughout meiotic prophase. However, the extent of phosphorylation changes between early and mid-pachytene, when one phosphate group is probably added to each of the variants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00352179
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  • 8
    Electronic Resource
    Electronic Resource
    Association of the extra chromosome of tertiary trisomic male mice with the sex chromosomes during first meiotic prophase, and its significance for impairment of spermatogenesis (1979)
    Springer
    Chromosoma 73 (1979), S. 369-379 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Pachytene nuclei were studied in five tertiary trisomic male mice of Ts(113)70H and two of Ts(512)31H, with special attention given to the sex vesicles. Silver stained air dried cells analysed by light microscopy were used mainly, but in addition one sample of surface spread, ethanolic phosphotungstic acid stained nuclei was analysed by electron microscopy. With both techniques and both karyotypes, the extra chromosome (or the greater part of it) almost consistently aggregated with the sex chromosomes. Thereby, the chromatin structure of the extra chromosome as judged by a fine granular appearance resembled that of the sex chromosomes. The animals used ranged from almost azospermic to fertile oligospermic. This variation was not reflected in the position and morphology of the chromosomes 113 and 512. — Using the whole mount spreading EM technique within a Ts(113)70H tertiary trisomic, both 13;13;113 trivalents and 113 univalents were observed. The 13;13;113 trivalents showed a variety of morphologies, ranging from a situation showing classical partner exchange to complete synapsis between the two 13 homologues with the 113 telomeric region adhering. The latter configuration is thought not to lead to chiasma formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00288698
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  • 9
    Electronic Resource
    Electronic Resource
    Meiosis of T70H translocation trisomic male mice (1982)
    Springer
    Chromosoma 87 (1982), S. 303-313 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Meiosis of T70H/+,Ts(113)70H translocation trisomic male mice has been studied using C-banded preparations of multivalents at the first meiotic division, marker chromosomes at the second meiotic division, and sucrose-spread pachytene spermatocytes for the observation of synaptonemal complexes. During zygotene and pachytene the three marker chromosomes, 131 (long) and 113 (2 x, small) associate with the chromosomes 1 and 13 to form either a Chain of three plus bivalent (CIII+II), a Chain of four plus univalent (CIV+I) or a Chain of five (CV). During pachytene, the 113 univalent of the CIV+I configuration shows association with the sex chromosomes in the sex vesicle while for CV, the unpaired segment of chromosome 1 can do so. — The frequencies of the multivalent configurations during late diplotenemetaphase I were CIII+II, 47.6%, CIV+I, 34.5% and CV, 14.4%. However, among late diplotene-early diakinesis cells, the frequency of CIV+I was 12.9% while in (late) spermatocytes with contracted bivalents it was 45.7%. — The notion that proximity of the interstitital chiasma of chromosome 13 to the centromere affects the chances of non-disjunction for these centromeres within the multivalent (i.e., adjacent 2 segregation) has been strengthened by the observed adjacent 2 frequency of 13.0% in the translocation trisomics compared to the 26.3% found in T70H/+ translocation heterozygotes with more proximal chiasmata. Thus, for reciprocal translocations between acrocentric chromosomes, a proximally located chiasma in an interstitial segment enhances the chance of adjacent 2 segregation. — Other parameters of irregular chromosome behaviour at anaphase I, such as equational separation of chromosome 113 into chromatids and non-disjunction of normal bivalents, were increased in the translocation trisomics when compared with T70H/+ translocation heterozygotes, especially among adjacent 2 segregating cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327632
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  • 10
    Electronic Resource
    Electronic Resource
    Meiosis of T70H translocation trisomic male mice (1982)
    Springer
    Chromosoma 87 (1982), S. 315-325 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Meiosis of T70H/+, Ts(113)70H translocation trisomic male mice has been studied using C-banded preparations and 3H-thymidine autoradiography of the first meiotic division. Epididymal sperm counts and sperm morphology scores were also collected. As reported earlier, at the first meiotic division the translocation involved chromosomes 1, 13, 131 and 113 (twice) formed mainly three multivalent configurations: Chain III+II, CIV+I and CV. — The autoradiographic study indicated an abnormal, precocious spiralization pattern for the chromatin in CIV+I primary spermatocytes. These cells, occurring together with the CIII+II and CV configurations in recognizable groups, usually descending from single spermatogonial stem cells, are delayed through meiotic prophase. Both delay and disturbed chromosome spiralization in these cells are attributed to the uniform association of the univalent (I) chromosome 113 with the sex chromosomes during pachytene. Primary spermatocytes of the CIV+I configuration and those carrying a CV take longer to develop from metaphase I into secondary spermatocytes than does the CIII+II type. — In T70H tertiary trisomics with a similar chromosome imbalance, the majority of primary spermatocytes degenerates during the diakinesis-metaphase I stages of meiosis. Fertility is low in contrast to the translocation trisomics. Comparison between the two types leads to the conclusion, that trisomy per se reduces the size of the testes and that the univalent containing CIV+I primary spermatocytes, contrary to the almost uniformly 113 univalent carrying spermatocytes of the T70H tertiary trisomics are rescued by the neighbouring CIII+II and CV carrying cells to form normal secondary spermatocytes and morphologically normal sperm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327633
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