ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Wiley-Blackwell  (71)
  • Springer  (52)
  • American Meteorological Society
  • 1975-1979  (123)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Mathematical principles in afferent visual neurons: Differentiation, integration and transient proportionality related to receptive fields and shift-effect (1976)
    Springer
    Bulletin of mathematical biology 38 (1976), S. 253-267 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The dual reciprocal and antagonistic organization of B- and D-neurons of the afferent visual system is obtained using differentiation and integration as mathematical equivalents of visual information processing by an impulse frequency code. The spatial and temporal derivatives lead to the transient responses. A constant and a time-dependent term proportional to the luminance distribution describe the sustained response components and the shift-effect of retinal on- and off-center ganglion cells. Receptive field properties of lateral geniculate cells and their antagonistic shift-effect are obtained by passing the retinal output, i.e. the difference between B- and D-neurons' activity, once again through the same operations. However, the factor of proportionality is applied to the retina alone. The surprisingly small difference between retinal and geniculate receptive field properties on the one hand and the dramatic change from a synergistic to an antagonistic shift-effect on the other hand are thereby explained. The theory offers an understanding of a a possible functional significance of the shift-effect as a mechanism of transientrestoration of visual information, which prevents the system from total fading by means of shifts of the retinal image, normally produced by eye movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02459558
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Der Einfluß von Koffein auf die motorische Reaktions- und die visuell-mentale Verarbeitungszeit (1979)
    Springer
    European journal of nutrition 18 (1979), S. 51-61 
    Details
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The effect of coffee without and with caffeine (200 mg) on the performance of “awake” respectively “fatigued” subjects was proved. 5 females and 7 males (22 to 32 years) were chosen for the cross-over double-blind study. Motor reaction time, visual-mental processing time, reading-speed and reading-errors were recorded. Further experiments under aggravated conditions were carried out. In the morning (“awake”) caffeine increases the efficiency of all parameters excepted the reading errors. At night (“fatigued”) the increase by caffeine is insignificant. Even in some subjects caffeine decreases the speed of reading and increases the number of errors. Under test-conditions, which were aggravated by strong acoustical disturbance, caffeine does not improve efficiency, compared with caffeine-free coffee. Overriding into the range of decreasing performance in spite of increasing central activity was not found under any test-condition.
    Notes: Zusammenfassung In einer Doppelblindstudie wurden an 12 Probanden im Alter von 22 bis 32 Jahren die Wirkung von koffeinhaltigem und koffeinfreiem Kaffee für zwei Befindenszustände „wach“ und „müde“ untersucht. Bei gleicher Dosierung von 200 mg Koffein wurden die Parameter motorische Reaktions-, die visuell-mentale Verarbeitungszeit sowie die Lesegeschwindigkeit und die Lesefehler registriert. Zusätzlich wurden Messungen unter erschwerten Bedingungen durchgeführt. Im Befindenszustand „wach“ am Morgen wirkt koffeinhaltiger Kaffee bis auf die Lesefehler in allen Parametern signifikant leistungssteigernd. Nachts, im Befindenszustand „müde“, bewirkt koffeinhaltiger Kaffee nur eine unwesentliche Leistungsverbesserung. Bei den Parametern Lesegeschwindigkeit und Lesefehler ist mit Koffein bei einzelnen Versuchspersonen eine Leistungseinbuße feststellbar. Auch unter Versuchsbedingungen mit erhöhten Anforderungen durch akustischen Störeinfluß war unter Koffein keine Leistungserhöhung gegenüber koffeinfreiem Kaffee zu beobachten. Eine übersteuerung in den Bereich abnehmender Leistung bei zunehmender Aktivität fand unter keiner Versuchsbedingung statt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02026537
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Zur Mathematik des tierischen Wachstums (1978)
    Springer
    Helgoland marine research 31 (1978), S. 499-526 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The parameters of the Gompertz function, the Bertalanffy function, and the reciprocal function (Krüger, 1962) are calculated for comparison using growth data obtained by Weymouth et al. (1930, 1931) for the razor clam from ten localities and the tuna fish. An new method is employed for the determination of growth parameters under the conditions of linear relations between the power ofe and the linear values of size in the Bertalanffy function and its natural logarithm in the Gompertz function. Both equations may therefore be solved by the well known method of linear regressions analysis. The method delivering optimal parameters for the Bertalanffy and the Gompertz function is described in a methodological chapter. Compared to the other functions the Gompertz delivers the best results for the growth curves of the arctic mussels including an inflection point. For curves without inflection points less good results are obtained. Deviations in the numeration of age are compensated in the Gompertz function by the parameterB. This parameter represents the difference between the natural logarithms of the upper limit size and the size at the age zero (normally corresponding to the size at birth). The parameterC includes the description of the curvature of the growth curve. A disadvantage of the Gompertz function is, that the upper limit of the equation is very near to the highest numbers evaluated and may be exceeded by real observations. A disadvantage of the reciprocal function is that the calculated inflection point does not correspond to the real inflection point. The result obtained for the relationship between length and weight of tuna fish show that the Gompertz function is exactly compatible with the allometric formula. It delivers for the summing up of the allometric formula the same solution as that reached by the reciprocal function. The three formulas employed are of the same structure, differing only in the use of linear numbers, logarithms or powers ofe. They deliver good approximations of growth data, but cannot be regarded as exact solutions for the mathematica description of growth curves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02189497
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Dissociation constants of the ampholyte glycine in 50 mass % methanol-water from 5 to 55°C, with related thermodynamic quantities (1976)
    Springer
    Journal of solution chemistry 5 (1976), S. 333-343 
    Details
    ISSN: 1572-8927
    Keywords: Zwitterions ; ampholyte ; dissociation constant ; glycine ; solute-solvent interactions ; ionization ; activity coefficient ; methanol-water ; aqueous mixture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The two thermodynamic dissociation constants of glycine at 11 temperatures from 5 to 55°C in 50 mass % methanol-water mixed solvent have been determined from precise emf measurements with hydrogen-silver bromide electrodes in cells without liquid junction. The first acidic dissociation constant (K 1)for the process HG+⇌H++G± is expressed as a function ofT(oK) by the equation pK 1 = 2043.5/T − 9.6504 + 0.019308T. At 25°C, pK 1is 2.961 in the mixed solvent, as compared with 2.350 in water, with ΔH°=1497 cal-mole−1, ΔG°=4038 cal-mole−1, ΔS°=−8.52 cal-°K−1-mole−1, and ΔC p o =−53 cal-°K−1-mole−1. The second acidic dissociation constant (K 2)for the process G±⇌H++G− over the temperature range studied is given by the equation pK 2 = 3627.1/T − 7.2371 + 0.015587T. At 25°C, pK 2is 9.578 in MeOH−H2O as compared with 9.780 in water, whereas ΔH° is 10,257 cal-mole−1, ΔG° is 13,063 cal-mole−1, ΔS° is −9.41 cal-°K−1-mole−1, and ΔC p o is −43 cal-°K−1-mole−1. The protonated glycine becomes weaker in 50 mass % methanol-water, whereas the second dissociation process becomes stronger despite the lower dielectric constant of the mixed solvent (ω=56.3 at 25°C).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00647198
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Transition probabilities for N IV, O V and O VI (1979)
    Springer
    Astrophysics and space science 60 (1979), S. 99-117 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Dipole lengths and dipole velocities have been determined for a series of transitions in N IV, O V and O VI. Some of these transitions are of astrophysical interest and the remainder were computed to give a more complete picture of the transitions in the respective ions. With the dipole length and dipole velocity known the line strengths and, therefore, the transition probabilities can be readily obtained. Agreement between dipole length and dipole velocity has been obtained in most cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00648246
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    A simple calculation of the angular distribution of sputtered atoms (1975)
    Springer
    The European physical journal 272 (1975), S. 127-130 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Angular distributions of atoms sputtered with fast ions from smooth amorphous targets are estimated by a straightforward treatment of the collision cascade. When the geometrical situation at oblique ion impact is considered, the angle of maximum emission and the sputtering yield in dependence on the angle of ion incidence are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01408437
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Fourier transform nuclear magnetic resonance studies of199Hg (1975)
    Springer
    The European physical journal 273 (1975), S. 325-330 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract 199Hg Fourier Transform NMR studies of various solutions of diverse mercury salts in H2O and D2O or in the appropriate protonated and deuterated acids are reported for both Hg 2 ++ and Hg++. In the different solutions investigated the199Hg line positions depend on the concentration of the solution, on the solvents and their isotopic composition and on the temperature of the sample. A ratio of the Larmor frequency of199Hg and of2H in a Hg(NO3)2 solution in dilute DNO3 is given. Using this ratio and the measured chemical shifts, a ratio of the Larmor frequencies of199Hg for infinite dilution relative to2H in pure D2O is given. From this a gI-factor for199Hg is derived and compared with the gI-factor of an optical pumping experiment. The resulting shielding constant is σ* (hydrated199Hg++ versus199Hg atom)=−24.32(5) · 10−4. This yields an atomic reference scale for all measured NMR line shifts of mercury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01435574
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    On the accuracy of soft-photon approximations for resonance free-free transitions (1978)
    Springer
    The European physical journal 287 (1978), S. 7-13 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The connection between resonances occuring in the scattering of electrons on atoms (molecules) with or without the presence of a classical laser field is demonstrated for aN-state model-atom in 1st order perturbation theory with respect to the laser field. It is possible to predict the position, the shape and the background of resonances in the laser field from the sole knowledge of the corresponding scattering amplitudes without the laser field. At first, a soft-photon approximation for individual partial wave amplitudes is derived. This approximations is then tested numerically for a 2-state square well potential model. Details about the accuracy of the soft-photon approximation are obtained by comparing with the numerically exact results. Finally our findings are applied to give an interpretation of recent experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01408353
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Air ion action on bacteria (1975)
    Springer
    International journal of biometeorology 19 (1975), S. 65-71 
    Details
    ISSN: 1432-1254
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Earlier work by three different investigators suggests that a biologically active radical is formed when small air ions react with water. Experiments undertaken to determine whether the hypothetical radical participates in the lethal action of negative air ions on M. pyogenes aureus revealed no evidence of such an effect. Evidently, lethality requires direct contact of air ions with microorganisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01459843
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Population genetics of unequal crossing over (1975)
    Springer
    Journal of molecular evolution 4 (1975), S. 201-247 
    Details
    ISSN: 1432-1432
    Keywords: Crossing over ; Unequal Crossing over ; Gene Duplication ; Selection Relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The population genetics of unequal crossing over was examined for an infinite population with random mating. The following cases were considered: 1. There is an initial portion of duplicated genes which offer the opportunity for unequal crossing over, but the primary event leading to the duplication does not occur any more (model 1a). 2. This primary event occurs with a certain (small) probability (model 1b). For both possibilities the long-term consequences for the distribution of “alleles” (i.e. the single gene, the duplicated gene, the triplicated gene etc.) were considered with the following additional assumptions: 1. No selection. 2. Selection with maximum fitness for an optimum “allele length” (i.e. number of gene repeats). 3. For model 1a, selection with general advantage of longer alleles over shorter ones was also examined. The results are briefly the following: In model 1a under assumption 1 the distribution of allele length tends with increasing generation number to a stationary state which depends on the initial allele distribution (i.e. on the initial frequency of the duplicated gene) but not on the frequency, P, of unequal crossing over; the stationary frequencies of the alleles decrease with increasing allele length. Under assumption 2 there is likewise a stationary allele distribution, but this depends on P as on the strength of selection and not on the initial allele distribution; it is concentrated more or less tightly around the optimal allele length. Under assumption 3 no stationary state seems to be reached: the mean and the standard deviation of the allele distribution increase steadily with the generation number. In model 1b under assumption 1, with certainty no stationary distribution exists. Under assumption 2 the situation is the same as that in model 1a; the stationary distribution of allele length is identical with that in model 1a for the same P and same selection strength, quite independent of the probability of the primary event. The results were discussed with respect to empirical examples in which unequal crossing over is expected to be important, for example human haptoglobins, immune globulin determining cistrons, and nucleolus organizer regions. The consequences of selection relaxation were considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01732983
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...