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  • Springer  (64)
  • 1980-1984  (64)
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  • 1
    Electronic Resource
    Electronic Resource
    Physical and biological processes in a Macrocystis pyrifera community near Valdivia, Chile (1982)
    Springer
    Oecologia 55 (1982), S. 1-6 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary From October 10, 1979 to August 26, 1981 we investigated the effect of physical disturbance, herbivory and algal-algal competition on the dynamics of the Macrocystis community near Valdivia, Chile. The most abundant herbivore, Tegula atra, was continuously removed from one of two sites with high initial Tegula density (control and Tegula-removal rocks) and added to one of two sites where Tegula was initially absent (Tegula-addition and addition-control rocks). Macrocystis was rare at the beginning of the study. From October 1980 to April 1981 we continuously removed Macrocystis from an additional rock near the addition-control rock. On each site the response of the algal community was monitored by photographing 9, 0.25 m2 permanent quadrats at 2–4 week intervals. Tegula had little effect on Macrocystis and there were no other important herbivores present. Each summer Macrocystis dominated all 4 sites of the Tegula experiment and Tegula migrated towards the intertidal to feed. Macrocystis was reduced each winter by winter storms, the holdfasts (but not the canopy) surviving the first winter but not the second. The Macrocystis removal rock was dominated by lower growing perennial algae, indicating a competitive hierarchy among the algae of the form: Macrocystis〉perennial algae〉ephemeral algae〉encrusting algae. Except for the presence of a competitive hierarchy among the algae and the importance of winter storms, Chilean kelp communities share few of the organizational features of their northern hemisphere counterparts. Marine mammals (excluding man) do not prey on algal consumers (Tegula and the urchin, Loxechinus albus) and these consumers have little effect on perennial macroscopic algae. Urchins apparently feed only on drift algae. Species richness in the algal community is low.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386710
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  • 2
    Electronic Resource
    Electronic Resource
    Load size and energy delivery in birds feeding nestlings: Constraints on and alternative strategies to energy-maximization (1983)
    Springer
    Oecologia 56 (1983), S. 93-98 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Orians-Pearson model of central place foraging for multiple-prey loaders assumes, as does most of current foraging theory, (i) that the quantity to be maximized is rate of energy delivery, and (ii) that the capacity of the foraging animal is the only relevant constraint on this rate. When applied to the case of birds feeding nestlings the model predicts, therefore, that the parents should select whichever load size maximizes the rate of energy delivery to the young. We assume here (i) that the parents could alternatively maximize the rate of energy delivery to the nest (m-strategy), maximize the time available for activities other than foraging (e.g. brooding) (b-strategy), or minimize the frequency of visits to the nest (v-strategy). We further assume (ii) that the nestlings impose constraints on the foraging behaviour of their parents in that there is a maximum load size that a brood can receive, as well as a maximum and a minimum rate of energy delivery that is acceptable. These three quantities are increasing functions of the age of the nestlings. Load size as a function of the age of the nestlings is predicted to increase initially and then to approach either the load size corresponding to maximum parental efficiency (m- and b-strategies) or a larger load size (v-strategy). For the b- and v-strategies rate of energy delivery is predicted to correspond to the minimum requirement of the nestlings throughout the nestling period. For the m-strategy energy delivery is predicted to be the maximum energy requirements of the nestlings initially, and then to level off to the energy delivery rate that corresponds to the maximum parental efficiency. As these strategies are not always compatible, foraging behaviour in a particular case may be an adaptive compromise between them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378222
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  • 3
    Electronic Resource
    Electronic Resource
    Crystal growth of calcium apatites in dilute solutions containing fluoride (1981)
    Springer
    Calcified tissue international 33 (1981), S. 431-439 
    Details
    ISSN: 1432-0827
    Keywords: Apatite ; Fluorhydroxyapatite ; Crystal growth ; Kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The kinetics of seeded crystal growth of calcium apatites were studied in dilute supersaturated solutions at various levels of fluoride concentrations. Initial precipitation rates were enhanced by fluoride concentrations higher than 0.05 ppm. The analytical results are consistent with the precipitation of fluoridated hydroxyapatites, Ca5Fx-(OH)1−x(PO4)3, FHA. The degree of fluoridation, X, appears to be determined by the activity of HF in solution, which varies for the various initial fluoride levels but remains fairly constant during precipitation. Thus the composition of the precipitating phase was the same for a given solution whether 25 or 10 mg of hydroxyapatite was added as seeds. All the experimental results are consistent with the BCF theory, which relates the mean linear rate of growth, RL, to the supersaturation, DS, by the expression RL=C1T(DS-1)1n(DS)tanh(C2/T 1n DS), in which DS is the supersaturation defined by mean molar activities with respect to the precipitating FHA, T the absolute temperature, and C1 and C2 are constants calculated from the experimental results. Consequently, the crystal growth appears to take place in surface kinks and to be controlled by surface diffusion. Since crystal growth in most biological systems takes place at fluoride concentrations within the experimental range used, it seems probable that it occurs along the model advanced in the present investigation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409467
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  • 4
    Electronic Resource
    Electronic Resource
    Equilibrium dialysis and ultrafiltration studies of calcium and phosphate binding by human salivary proteins. Implications for salivary supersaturation with respect to calcium phosphate salts (1982)
    Springer
    Calcified tissue international 34 (1982), S. 531-538 
    Details
    ISSN: 1432-0827
    Keywords: Saliva ; Calcium ; Phosphate ; Ion-binding ; Supersaturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Previous ultrafiltration studies indicated that up to one-half of the calcium and two-thirds of the phosphate in human salivary secretions may be bound by salivary proteins. Since this binding is an important variable in determining the extent of salivary supersaturation with respect to calcium phosphate salts, and since the amount of binding reported is surprisingly large, calcium and phosphate ion-binding by salivary macromolecules has been reexamined. From experiments using equilibrium dialysis, it was found that (1) the fraction of salivary calcium involved in macromolecular complexes ranges from a few percent for unstimulated secretions, to no more than about 10% for stimulated glandular salivas, and (2) salivary proteins do not bind phosphate ions to any significant extent. These findings, and experiments using an improved ultrafiltration membrane, indicate that the earlier results were artifacts of the ultrafiltration technique. Fractionation of salivary proteins, followed by equilibrium dialysis measurements, showed that the anionic proline-rich proteins and a basic proline-rich glycoprotein are responsible for most of the calcium binding now observed. The finding that macromolecular complexes of salivary calcium and phosphate have been overestimated in the past, leads to the conclusion that salivary calcium and phosphate ion activities in stimulated salivary secretions may be up to 50 to 100% higher than previously thought. Revised values were therefore used to recalculate the degree of salivary supersaturation with respect to calcium phosphate salts. The results indicate that stimulated salivary secretions are supersaturated with respect to dicalcium phosphate dihydrate; this is a substantially greater degree of supersaturation than previously reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411299
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  • 5
    Electronic Resource
    Electronic Resource
    Rapid spectrophotometric determination of chlorate with dimedone bisthiosemicarbazone monohydrochloride (1984)
    Springer
    Microchimica acta 84 (1984), S. 295-302 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Verwendbarkeit von I als Reagens für die rasche und empfindliche spektrophotometrische Bestimmung von 0,5–5,0 ppm Chlorat durch Oxydation von I in 70%iger Perchlorsäure und Messung des gelben Reaktionsproduktes wurde untersucht. Die molare Absorptivität bei 417 nm beträgt 1,86×104 l·mol−1·cm−1. Die relative Standardabweichung beträgt 1,6% für 2,5 ppm Chlorat.
    Notes: Summary Dimedone bisthiosemicarbazone monohydrochloride has been examined to evaluate its usefulness as a reagent for rapid and sensitive Spectrophotometric determination of chlorate (0.5–5.0 ppm) by oxidation of the reagent in 70% perchloric acid medium and measurement of the yellow product. The molar absorptivity at 417 nm is 1.86×104 l·mole−1·cm−1. The relative standard deviation is 1.6% for 2.5 ppm of chlorate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01212394
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  • 6
    Electronic Resource
    Electronic Resource
    *-Products on D 1 (ℂ), S 2 and related spectral analysis (1983)
    Springer
    Letters in mathematical physics 7 (1983), S. 181-193 
    Details
    ISSN: 1573-0530
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We provide expressions to find recursively any 2-cochain of each of two invariant formal differentiable deformations of C ∞(S 2), here called * and *″. They are obtained in ways similar to those followed to obtain, respectively, Wick's and Moyal's deformations on ℂ n . We provide the expression for the corresponding *-exponential, on Poincaré's disk and on S 2, and its proper spectral decomposition. No proofs are given in this letter. For detailed proofs in the case of D 1 (ℂ), see [1]. The proofs for the case S 2 follow the same pattern; however, [1] does not contain the spectral analysis given here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400432
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  • 7
    Electronic Resource
    Electronic Resource
    Professor Goodman's stories (1981)
    Springer
    Synthese 〈Dordrecht〉 46 (1981), S. 355-358 
    Details
    ISSN: 1573-0964
    Source: Springer Online Journal Archives 1860-2000
    Topics: Natural Sciences in General , Philosophy
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01130047
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  • 8
    Electronic Resource
    Electronic Resource
    Mendelian recessive ratios in acute poststreptococcal glomerulonephritis (1982)
    Springer
    Cellular and molecular life sciences 38 (1982), S. 918-920 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A prospective study of 15 families (61 siblings) of index cases of acute poststreptococcal glomerulonephritis detected a proportion of 0.260±0.016 SEM. This is an excellent fit for a single autosomal recessive trait.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01953653
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of EDITEMPA on dental calculus and caries formation in vivo (1983)
    Springer
    Calcified tissue international 35 (1983), S. 362-365 
    Details
    ISSN: 1432-0827
    Keywords: N,N,N',N'-ethylenediamine (tetramethylene phosphonic acid) ; Calculus in beagles ; Anticaries effects ; Rat caries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary N,N,N',N'-ethylene diamine tetra (methylene phosphonic acid)—EDITEMPA—was highly effective in reducing dental calculus formation in beagle dogs when applied topically as a 1% solution or in a mouth rinse. A dose-response study in 40 beagles for 12 weeks with dentifrices containing 1, 2, 2.75, and 2.75% EDITEMPA+0.1% NaF gave a significant (α=0.05) reduction in calculus formation. Based on these results, it was also concluded that 0.1% NaF did not affect the anticalculus activity of 2.75% EDITEMPA. The effect of EDITEMPA dentifrice on dental caries in rats was also studied. A dentifrice containing 1.69% EDITEMPA significantly (α〈0.01) reduced smooth and fissure caries in rats when applied topically. Collectively, the data suggested that EDITEMPA was an effective anticalculus agent and that it did not damage developing enamel in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405059
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  • 10
    Electronic Resource
    Electronic Resource
    Inhibition of apatite crystal growth by the amino-terminal segment of human salivary acidic proline-rich proteins (1984)
    Springer
    Calcified tissue international 36 (1984), S. 651-658 
    Details
    ISSN: 1432-0827
    Keywords: Salivary proteins ; Hydroxyapatite ; Adsorption ; Precipitation-inhibitor ; Phosphoserine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Inhibition of seeded apatitic crystal growth by human salivary acidic proline-rich phosphoproteins (PRP) has been related to their adsorption onto the apatite seeds. The amino-terminal 30-residue segment of the PRP makes an important contribution to this adsorption. This peptide (PRP1(T1)) and its dephosphorylated analogue from PRP3 (PRP3(T1)DP) were prepared. They have identical sequences, except the phosphates at residues 8 and 22 in PRP1(T1) are absent from PRP3(T1)DP. Adsorption of these peptides onto hydroxyapatite and their effect on crystal growth from a defined supersaturated solution was studied. Adsorption behavior was adequately described by the Langmuir adsorption isotherm. The adsorption affinity constant of PRP1(T1) (K=20,200 ml/µmol) was more than 10 times the corresponding value for PRP3(T1)DP (1,800 ml/µmol), and similar to that of the parent protein, PRP1 (26,200 ml/µmol). Inhibition of crystal growth by the peptides was interpreted in terms of the fractional coverage of the maximum number of adsorption sites (as derived from the adsorption isotherms), suggesting that the molecules block, by adsorption, specific growth sites on these surfaces. Comparison of precipitation kinetics showed that PRP1(T1) is a more effective inhibitor than PRP3(T1)DP at the same initial concentration (10−6−10−7 M). However, on the basis of per mol adsorbed, PRP3(T1)DP displays a greater inhibitory activity; such a behavior is consistent with a more open molecular structure which blocks more growth sites per mol adsorbed than PRP1(T1). Because of its high affinity constant, preadsorbed PRP1(T1) remains in the condensed state in the supersaturated solution used, whereas the preadsorbed PRP3(T1)DP molecules desorb to some extent, resulting in a decrease in inhibitory activity. The results show that the amino-terminal segment of the PRP and the two phosphoserine residues present in this segment are particularly important in the function proposed for these proteins in the oral environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405385
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