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  • Springer  (25)
  • 1995-1999  (11)
  • 1975-1979  (14)
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  • 1
    Electronic Resource
    Electronic Resource
    Reserves in sexual forms ofAcromyrmex octospinosus (Reich) (Formicidæ, Attini) (1979)
    Springer
    Insectes sociaux 26 (1979), S. 113-122 
    Details
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume 1 - Le couvain et les imagos de sexués proviennent de colonies d'Acromyrmex octospinosus élevées au laboratoire. 2 - Les sexués sont beaucoup plus grands que les ouvrières. 3 - Il existe une différence entre les mâles et les femelles non fécondées dans le métabolisme des lipides: celles-ci ont une quantité de lipides 7 fois plus élevée que les mâles. 4 - En l'absence de nourriture, la moyenne de vie des mâles adultes est en moyenne de 5,3 jours, alors qu'elle peut atteindre 109 jours (en moyenne 55,4 jours) chez les femelles adultes non fécondées. 5 - Pendant la période de privation de nourriture, les mâles utilisent presque toutes leurs réserves de lipides et d'hydrates de carbone, alors que les femelles non fécondées n'utilisent qu'une partie des lipides neutres. 6 - Le « comportement » des femelles non fécondées paraît adapté à la conservation des réserves énergétiques.
    Notes: Summary 1 - Sexual brood and adults were taken from laboratory colonies ofAcromyrmex octospinosus (Reich) for observation and analysis. 2 - The reproductive castes were much larger than the workers. 3 - A sex difference in lipid metabolism was found between the reproductive castes, adult gynes possessing seven times the amount of lipid found in males. 4 - Starved adult males lived for an average of 5.3 days, but gynes survived for up to 109 days (average = 55.4 days). 5 - During starvation, adult males used nearly all of their lipid and carbohydrate reserves, while gynes utilised only neutral lipids to any extent. 6 - The behaviour of gynes appeared to be adapted to the conservation of energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02223505
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  • 2
    Electronic Resource
    Electronic Resource
    Electrophoretic behaviour and viscosities of metal oxides in mixed surfactant systems (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 72-80 
    Details
    ISSN: 1435-1536
    Keywords: Key words Electrokinetics ; mixed surfactant adsorption ; viscosity ; anatase ; alumina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The electrokinetic behavior and viscosity of anatase and alumina in mixed-surfactant solutions were investigated. Sodium dodecylsulfate and nonionic polyoxyethylene ethers were investigated as model surfactants. Pure nonionic surfactants adsorbed on anatase and coated the particles, so that the zeta potential was nearly zero near the critical micelle concentration of surfactant. At higher surfactant concentrations, an increase in the zeta potentials was observed, suggesting a change in the microstructure of the adsorbed layer. Addition of nonionic surfactant to positively charged anatase and alumina with some preadsorbed sodium dodecylsulfate reversed the surface charge of the oxide to negative, indicating enhanced coadsorption of the anionic surfactant. At higher concentrations of the nonionic surfactant, the charge reversed back to positive. Nonionic surfactants did not reverse the surface charge of these oxides in the absence of the anionic surfactant. Coenhanced adsorption of nonionic and anionic surfactants was used to stabilize alumina at the isoelectric point, where neither surfactant adsorbed appreciably on its own. These results suggest a dramatic change in conformation of the surfactant chains in mixed systems. Further explanation and justification of the proposed changes in adsorbed surfactant conformation require spectroscopic evidence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050211
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  • 3
    Electronic Resource
    Electronic Resource
    An analysis of approximations for maximizing submodular set functions—I (1978)
    Springer
    Mathematical programming 14 (1978), S. 265-294 
    Details
    ISSN: 1436-4646
    Keywords: Heuristics ; Greedy Algorithm ; Interchange Algorithm ; Linear Programming ; Matroid Optimization ; Submodular Set Functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract LetN be a finite set andz be a real-valued function defined on the set of subsets ofN that satisfies z(S)+z(T)≥z(S⋃T)+z(S⋂T) for allS, T inN. Such a function is called submodular. We consider the problem maxS⊂N{a(S):|S|≤K,z(S) submodular}. Several hard combinatorial optimization problems can be posed in this framework. For example, the problem of finding a maximum weight independent set in a matroid, when the elements of the matroid are colored and the elements of the independent set can have no more thanK colors, is in this class. The uncapacitated location problem is a special case of this matroid optimization problem. We analyze greedy and local improvement heuristics and a linear programming relaxation for this problem. Our results are worst case bounds on the quality of the approximations. For example, whenz(S) is nondecreasing andz(0) = 0, we show that a “greedy” heuristic always produces a solution whose value is at least 1 −[(K − 1)/K] K times the optimal value. This bound can be achieved for eachK and has a limiting value of (e − 1)/e, where e is the base of the natural logarithm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01588971
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  • 4
    Electronic Resource
    Electronic Resource
    Earthworm communities in native savannas and man-made pastures of the Eastern Plains of Colombia (1998)
    Springer
    Biology and fertility of soils 28 (1998), S. 101-110 
    Details
    ISSN: 1432-0789
    Keywords: Key words Abundance ; Biomass ; Diversity ; Earthworm community ; Tropical savannas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The structure and seasonal changes of earthworm communities were evaluated in a natural savanna and in a improved grass-legume pasture in a Colombian oxisol over a period of 18 months. One plot of 90×90 m was isolated in each of the systems and each month five samples of 1 m2×0.5 m and ten of 20×20×20 cm were randomly selected from a stratified block design. Species richness was similar in the two evaluated plots (seven species), whereas diversity measured by the index, H (Shannon and Weaver 1949) was clearly different, i.e. H=2.89 in natural savanna and H=1.29 in pasture. This is explained by differences in earthworm community structure. The average annual density in the savanna was 49.8, ranging from 10.8 to 135.8 individuals (ind) m–2, and biomass was 3.3 g m–2 (hand-sorting method), ranging from 0.9 to 11.5 g m–2. In the man-made pasture, density was 80.1 ind m–2 on average, ranging from 24 to 215.8 ind m–2 and biomass was more than tenfold higher, ranging from 29.2 to 110.4 g m–2. This was especially due to the presence of a large glossoscolecid anecic species, Martiodrilus carimaguensis Jiménez and Moreno, which has been greatly favoured by conversion of savanna to pasture. Endogeic species were dominant in the natural savanna whereas the anecic species accounted for 88% of total earthworm biomass in the pasture. Total earthworm density and biomass were significantly different in the two systems studied (t-test). The results indicate a clearly positive response of earthworm communities to improved pastures, a type of land use that is being increasingly adopted in moist neotropical savannas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050469
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  • 5
    Electronic Resource
    Electronic Resource
    Stability in a class of discrete time models of interacting populations (1977)
    Springer
    Journal of mathematical biology 4 (1977), S. 265-274 
    Details
    ISSN: 1432-1416
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Summary Effective Lyapunov and Lyapunov-like functions for a class of discrete time models of interacting populations are presented. These functions are constructed on the biologically meaningful principle that a viable population must absorb energy from external sources when its density is low and it must dissipate energy to the environment when its density is high. These functions can be used to establish that a discrete time model is globally stable or that its solutions are ultimately confined to an acceptable region of the state space. The latter is especially interesting when the model has chaotic solutions. These methods are applied to a single species model and a model of competition between two species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280976
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  • 6
    Electronic Resource
    Electronic Resource
    Comparison between pressure-volume and dewpoint-hygrometry techniques for determining the water relations characteristics of grass and legume leaves (1979)
    Springer
    Oecologia 41 (1979), S. 77-88 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The water relations characteristics of three grass species (Panicum maximum var. trichoglume, Cenchrus ciliaris, Heteropogon contortus), and a legume (Macroptilium atropurpureum) grown in the field were measured using both a modified pressure/volume technique with pressure bomb measurements on single leaves and a dewpoint hygrometry technique applied to fresh and to frozen and thawed leaf discs. The two techniques agreed well in the estimates of osmotic potential at full turgor and the water potential at zero turgor. However, for parameters such as the relative water content at zero turgor, bound water and bulk modulus of elasticity there was a poor correlation between the estimates from the two methods. The pressure/volume technique gave less variable results and is more convenient for field use than the hygrometry technique. The determination of the modulus of elasticity from various functions relating pressure potential to relative water content is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344838
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  • 7
    Electronic Resource
    Electronic Resource
    MetateM: An introduction (1995)
    Springer
    Formal aspects of computing 7 (1995), S. 533-549 
    Details
    ISSN: 1433-299X
    Keywords: Modal and temporal logics ; Reactive systems ; Specification ; Prototyping ; Mechanical verification ; Non-procedural languages ; Logic programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this paper a methodology for the use of temporal logic as an executable imperative language is introduced. The approach, which provides a concrete framework, calledMetateM, for executing temporal formulae, is motivated and illustrated through examples. In addition, this introduction provides references to further, more detailed, work relating to theMetateM approach to executable logics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01211631
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  • 8
    Electronic Resource
    Electronic Resource
    Inheritance of resistance to potyviruses in Phaseolus vulgaris L. IV. Inheritance, linkage relations, and environmental effects on systemic resistance to four potyviruses (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 204-212 
    Details
    ISSN: 1432-2242
    Keywords: Plant virus resistance ; Azuki bean mosaic virus ; Cowpea aphid-borne mosaic virus ; Soybean mosaic virus ; Watermelon mosaic virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have examined the genetics of systemic resistance in Phaseolus vulgaris to azuki bean mosaic virus (AzMV) and cowpea aphid-borne mosaic virus (CABMV) and the relationship of this resistance to a phenotypically similar resistance to watermelon mosaic virus (WMV) and soybean mosaic virus (SMV). In P. vulgaris cv ‘Great Northern 1140’ (GN1140), resistance to SMV and WMV has been attributed to the genes Smv and Wmv, respectively, which have been shown to segregate as a unit. Systemic resistance to AzMV is conferred by two incompletely dominant alleles, Azm1 and Azm2, at unlinked loci. At least three resistance alleles must be present at these two loci for systemic resistance to be expressed in the plant. Systemic resistance to CABMV in GN 1140 is conditioned by a dominant allele that has been designated Cam2. Under some environmental conditions, a recessive allele at an unlinked locus, cam3, also controls a resistant response to CABMV. Resistance to AzMV and CABMV does not assort independently from Wmv/Smv, but also does not consistently cosegregate, suggesting that perhaps in each case one of the factors involved in resistance is associated with Smv/Wmv.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223377
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  • 9
    Electronic Resource
    Electronic Resource
    Inheritance of resistance to potyviruses in Phaseolus vulgaris L. IV. Inheritance, linkage relations, and environmental effects on systemic resistance to four potyviruses (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 204-212 
    Details
    ISSN: 1432-2242
    Keywords: Key words Plant virus resistance  ;  Azuki bean mosaic virus  ;  Cowpea aphid-borne mosaic virus  ; Soybean mosaic virus  ;  Watermelon mosaic virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We have examined the genetics of systemic resistance in Phaseolus vulgaris to azuki bean mosaic virus (AzMV) and cowpea aphid-borne mosaic virus (CABMV) and the relationship of this resistance to a phenotypically similar resistance to watermelon mosaic virus (WMV) and soybean mosaic virus (SMV). In P. vulgaris cv ‘Great Northern 1140’ (GN1140), resistance to SMV and WMV has been attributed to the genes Smv and Wmv, respectively, which have been shown to segregate as a unit. Systemic resistance to AzMV is conferred by two incompletely dominant alleles, Azm1 and Azm2, at unlinked loci. At least three resistance alleles must be present at these two loci for systemic resistance to be expressed in the plant. Systemic resistance to CABMV in GN 1140 is conditioned by a dominant allele that has been designated Cam2. Under some environmental conditions, a recessive allele at an unlinked locus, cam3, also controls a resistant response to CABMV. Resistance to AzMV and CABMV does not assort independently from Wmv/Smv, but also does not consistently cosegregate, suggesting that perhaps in each case one of the factors involved in resistance is associated with Smv/Wmv.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050115
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  • 10
    Electronic Resource
    Electronic Resource
    Antihypertensive activity of some novel pyridinylidene arylurea derivatives in spontaneously hypertensive rats (1979)
    Springer
    Cellular and molecular life sciences 35 (1979), S. 799-801 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 3 novel pyridinylidene arylurea derivatives were found to lower arterial pressure in spontaneously hypertensive rats. Their relative oral potency ranged from 6 to 32 times that of guanethidine. The onset of antihypertensive action following their oral administration was less than 1 h and the duration of action ranged from 8 to over 24 h. The antihypertensive activity of the pyridinylidene arylureas was found to be associated with depletion of tissue catecholamines. Compound C depleted cardiac norepinephrine with little or no effect on total brain norepinephrine levels. It is suggested that compound C may have useful antihypertensive properties without CNS depressant activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01968258
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