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  • 1
    Digitale Medien
    Digitale Medien
    Spacial distribution of photosynthetic capacity and performance in a mountain spruce forest of northern Germany (1977)
    Springer
    Oecologia 29 (1977), S. 329-340 
    Details
    ISSN: 1432-1939
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Net photosynthesis of Picea abies was measured in a spruce forest in northern Germany with temperature- and humidity-controlled cuvettes in 4 different crown layers on shoots of different ages. These measurments were performed such that temperature and humidity either followed ambient conditions or were kept constant. Annual courses of light-, temperature-, and humidity-related net photosynthesis were determined. Spruce had a remarkably constant rate of CO2 uptake from April to September for 1-year and older needles. Light saturation was achieved at 25 klx. Current year needles had the highest rates of CO2 uptake in early summer, but these rates decreased by autumn. Photosynthetic capacity decreased with needle age and, on a dry weight basis, it was higher in the shade than in the sun crown. The temperature optimum was between 13 and 23° C. Photosynthesis in spruce decreased when air humidity was low. The effect of the natural weather conditions on photosynthetic capacity was determined. The habitat is characterized by a high frequency of low light intensities (75% of total daytime below 20 klx) and cool temperatures (80% of daytime between 9 and 21° C). Low air humidity was only present when light intensities were high. The major limiting factor for production was low light intensities, which reduced photosynthetic capacity in the sun crown to 42% below maximum possible rates. Adverse temperatures reduced CO2 uptake by 28% and large water vapor pressure deficits reduced rates by only 2% compared with maximum possible rates. The limited adaptation to light is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00345806
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  • 2
    Digitale Medien
    Digitale Medien
    Spacial distribution of photosynthetic capacity and performance in a mountain spruce forest of Northern Germany (1977)
    Springer
    Oecologia 30 (1977), S. 239-248 
    Details
    ISSN: 1432-1939
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Growth and CO2 uptake in the crown of a spruce tree is described and the production processes of this evergreen conifer are compared with those of a deciduous beech. Spruce had 60% lower rates of net photosynthesis per dry weight than beech. But, beech had a 30% shorter growing season and a 84% smaller biomass than spruce. The annual CO2 gain was 40% lower in beech than it was in spruce. An analysis shows the following conclusions for this habitat. (1) The effect of a prolonged growing season is small. The annual CO2 gain of spruce would be reduced only by 9% if the growing season was the same length as for beech. (2) The annual CO2 gain would increase 14% if all needles in spruce were deciduous, because the current year needles have a higher average rate of CO2 uptake than 3-year old and older needles, but a lower average rate than 1- and 2-year old ones. However, the carbon balance of the tree shows that spruce could not afford to produce the existing needle biomass (14 t ha-1) each year. (3) If spruce were to produce the same deciduous foliage biomass during the same growing season as beech then total production by spruce would be reduced 67%. (4) The annual CO2 uptake by evergreen spruce was higher than deciduous beech not because of a long growing season, but because of the longevity of its needles, which during their total life time (an average of 5 years) have a two to three times greater CO2 uptake than a deciduous leaf in one summer season. The relatively small investment in current year needles produces an annually low, but long lasting assimilation of CO2.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01833630
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  • 3
    Digitale Medien
    Digitale Medien
    Light scattering at the liquid to glass transition (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 7074-7085 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Light scattering in a viscoelastic liquid is studied. The change from liquid to solid-like Brillouin spectra is explained using frequency dependent elasto-optic constants. Within a standard dielectric model microscopic formulas for these generalized frequency dependent constants and the spectra are obtained. The phenomenological pictures of light scattering in an amorphous solid and in a liquid are obtained as high and low frequency limits. The observation of a Rytov Dip in a system of optically isotropic particles is predicted for slow enough viscoelastic relaxation. Approximations using the Mode Coupling Theory allow the spectra to be expressed in terms of density fluctuations alone. The predictions of this theory for the spectra are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.461436
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  • 4
    Digitale Medien
    Digitale Medien
    Erratum: Scattering of highly vibrationally excited Li2 from He and Kr [J. Chem. Phys. 85, 7062 (1986)] (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 5986-5986 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.454771
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  • 5
    Digitale Medien
    Digitale Medien
    Localization of current dipoles with multichannel SQUID systems (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 3053-3060 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Current sources in the human body can be localized by measuring the biomagnetic fields with multichannel SQUID systems. Important system aspects are the noise level, the ambient field suppression, the dynamic range, the reliability, the number of channels, and the arrangement of gradiometers. From the user's point of view the most important quality factor is the accuracy with which a current dipole can be localized. A test procedure is proposed to determine the localization power of the system. A 31-channel-SQUID system is presented together with the results of the test. The crucial parts of the system determining the accuracy are pointed out.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1144359
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  • 6
    Digitale Medien
    Digitale Medien
    Distributed feedback laser line narrowing with external fiber resonators (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 1936-1938 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A simple distributed feedback (DFB) laser line narrowing arrangement consisting of an adapted coupler and a cleaved fiber end resonator has been realized. Linewidths below 100 kHz have been obtained for different commercial 1300 nm and 1550 nm DFB lasers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.99603
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  • 7
    Digitale Medien
    Digitale Medien
    Tracheal intubation and cervical spine excursion: direct laryngoscopy vs. intubating laryngeal mask (2001)
    Oxford, UK : Blackwell Science Ltd
    Anaesthesia 56 (2001), S. 0 
    Details
    ISSN: 1365-2044
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Until recently, the most appropriate technique of intubating a patient with a cervical spine injury has been the subject of debate. Tracheal intubation by means of the intubating laryngeal mask (Fastrach™), a modified conventional laryngeal mask airway, seems to require less neck manipulation. The aim of this study was to compare the excursion of the upper cervical spine during tracheal intubation using direct laryngoscopy with that during intubation via the laryngeal mask (Fastrach™), by examination of lateral cervical spine radiographs in healthy young patients. The intubating laryngeal mask (Fastrach™) caused less extension (at C1−2 and C2−3) than intubation by direct laryngoscopy. Direct laryngoscopy is still the fastest method to secure an airway provided no intubating difficulties are present. However, in trauma patients requiring rapid sequence induction and in whom cervical spine movement is limited or undesirable, the intubating laryngeal mask (Fastrach™) is a safe and fast method by which to secure the airway.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2044.2001.01869.x
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  • 8
    Digitale Medien
    Digitale Medien
    Portable cardiopulmonary support (ECPS) in the emergency room (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 53 (1998), S. 0 
    Details
    ISSN: 1365-2044
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2044.1998.tb15130.x
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  • 9
    Digitale Medien
    Digitale Medien
    Scattering of highly vibrationally excited Li2 from He and Kr (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 7062-7076 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Total integral scattering cross sections have been measured for Li2 molecules in selected rotational and vibrational states up to v=21. The vibrationally highly excited states with energies up to 80% of the dissociation energy were prepared by Franck–Condon laser pumping. With increasing vibrational quantum number the observed cross sections show first a 10% decrease followed by a 20%–25% rise. A model potential has been developed based on an ab initio potential for the vibrational ground state to account for the effect of vibrational stretching. The results provide for the first time direct information on the bond-distance dependence r of the complete potential hypersurface V(R,r,γ) (R distance between centers of mass and γ angle between r and R) of an atom–molecule system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.451393
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  • 10
    Digitale Medien
    Digitale Medien
    Water uptake profile response of corn to soil moisture depletion (2002)
    Oxford, UK : Blackwell Science, Ltd
    Plant, cell & environment 25 (2002), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The effects of soil moisture distribution on water uptake of drip-irrigated corn were investigated by simultaneously monitoring the diurnal evolution of sap flow rate in stems, of leaf water potential, and of soil moisture, during intervals between successive irrigations. The results invalidate the steady-state resistive flow model for the continuum. High hydraulic capacitance of wet soil and low hydraulic conductivity of dry soil surrounding the roots damped significantly diurnal fluctuations of water flow from bulk soil to root surface. By contrast, sap flow responded directly to the large diurnal variation of leaf water potential. In wet soil, the relation between the diurnal courses of uptake rates and leaf water potential was linear. Water potential at the root surface remained nearly constant and uniformly distributed. The slope of the lines allowed calculating the resistance of the hydraulic path in the plant. Resistances increased in inverse relation with root length density. Soil desiccation induced a diurnal variation of water potential at the root surface, the minimum occurring in the late afternoon. The increase of root surface water potential with depth was directly linked to the soil desiccation profile. The development of a water potential gradient at the root surface implies the presence of a significant axial resistance in the root hydraulic path that explains why the desiccation of the soil upper layer induces an absolute increase of water uptake rates from the deeper wet layers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3040.2002.00825.x
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