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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 178 (1996), S. 605-628 
    ISSN: 1432-1351
    Keywords: Crustacean ; Olfaction ; Mechanoreception ; Local interneurons ; Projection neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Neurons in the olfactory deutocerebrum of the spiny lobster, Panulirus argus, were recorded intracellularly and filled with biocytin. Recorded neurons arborized in the olfactory lobe (OL), a glomerular neuropil innervated by olfactory and some presumptive mechanosensory antennular afferents. The neurons responded to chemosensory input from the lateral antennular flagellum bearing the olfactory sensilla but not the medial flagellum bearing many non-olfactory chemosensory sensilla. Many neurons received additional mechanosensory input. Thus the OL integrates specifically olfactory with mechanosensory input. OL neurons had multiglomerular arborizations restricted to one or two of the three horizontal layers of the columnar glomeruli. OL local interneurons comprised “core” neurons with tree-like neurites and terminals in the base of the glomeruli and “rim” neurons with neurites surrounding the OL and terminals in the cap/subcap. The somata of OL local interneurons lay in the medial soma cluster (100000 somata). OL projection neurons arborized in the base of the glomeruli and ascended via the olfactory glomerular tract to the lateral protocerebrum. A parallel projection pathway is constituted by projection neurons of the accessory lobe, a glomerular neuropil without afferent innervation but intimate links to the OL. The projection neuron somata constituted the lateral soma cluster (200000 somata).
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 178 (1996), S. 579-604 
    ISSN: 1432-1351
    Keywords: Crustacean ; Chemoreception ; Mechanoreception ; Deutocerebrum ; Motoneurons ; Projection neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Neurons in the brain of the spiny lobster that respond to chemical and mechanical stimulation of the antennule (antenna I) were recorded and stained intracellularly. Described here are neurons that do not arborize in the olfactory and accessory lobes of the deutocerebrum, but rather primarily target the lateral and/or the median antennular neuropils of the deutocerebrum. Some of the neurons also extend into the antennal and tegumentary neuropils of the tritocerebrum and the neuropils of the median protocerebrum. Included are antennular sensory afferents, antennular motoneurons, projection neurons descending from the central brain, projection neurons ascending from the central brain and projection neurons descending from the eyestalk ganglia. Collectively, these neurons consitutute a novel antennular sensory pathway that is parallel to and independent of the antennular olfactory pathway. The novel pathway integrates mechanosensory and non-olfactory chemosensory information in the lateral and/or the median antennular neuropils, which also serve as lower motor centers of the antennule. Division of the arthropod deutocerebrum into two, functionally distinct chemosensory pathways may reflect differences in how chemosensory information is processed that is fundamental to understanding the origin of the sense of smell.
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  • 3
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The x-ray spectra of a plasma generated by heating CO2 and Ar clusters with high-intensity femtosecond laser pulses with q las≃1018 W/cm2 are investigated. Spatially resolved x-ray spectra of a cluster plasma are obtained for the first time. Photoionization absorption is observed to influence the spectral line profiles. The recorded features of the x-ray emission spectra definitely indicate the existence of a large relative number of excited ions (≃10−2–10−3) with energies of 0.1–1 MeV in such a plasma. Possible mechanisms underlying the acceleration of ions to high energies are discussed. It is shown that the experimental results can be attributed to the influence of ponderomotive forces in standing waves generated by the reflection of laser radiation from the clusters.
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  • 4
    ISSN: 1432-2048
    Keywords: Chaperone ; Chloroplasts ; Chromoplasts ; Heat-shock protein ; Secale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A partial cDNA which codes for the β-subunit of a plastidic chaperonin 60 (cpn60-β) from rye (Secale cereale L.) leaves was identified and sequenced, except for 46 amino acids of the N-terminus of the mature protein and the transit sequence. This is the first cpn60-β sequence determined for a monocotyledonous plant. Specific antibodies against cpn60-β were affinity-purified from an antiserum raised against the total soluble protein fraction of ribosome-deficient plastids. The localization of cpn60-β in chloroplasts or non-green plastids was confirmed by immunodetection in Percoll gradient-purified organelles. The expression and occurrence of cpn60-β was analysed by immunoblotting with the specific antibodies and Northern hybridization. The cpn60-β protein was constitutively expressed in various green and non-green tissues. It was evenly distributed along the major part of a rye leaf, while highest transcript levels occurred in the youngest and oldest leaf sections. The expression of the cpn60-β protein was not enhanced by a heat-shock treatment at 42 °C. The cpn60-β transcript and protein were more strongly expressed in various non-green, for instance etiolated, 70S-ribosome-deficient 32 °C-grown, or herbicide-bleached tissues, than in green leaves of rye. A rapid increase in the cpn60-β transcript level was also observed when green leaves were transferred from light to darkness while the protein level was not affected. The dark-induced increase in the cpn60-β transcript was totally suppressed in the presence of 2% sucrose. Inhibitor treatments suggested that the change in cpn60-β transcript level was not related to changes of the ATP supply of the tissue. While the large subunit of the photosynthetic protein ribulose-1,5-bisphosphate carboxylase was largely degraded during ripening of tomato fruits, high levels of cpn60-β were detected in tomato chromoplasts and in the yellow flower petals of Narcissus. Low levels of cpn60-β were detected in root tissue.
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  • 5
    ISSN: 1432-1017
    Keywords: Iron superoxide dismutase ; SOD ; X-ray absorption ; XAS ; Extended X-ray absorption fine structure ; EXAFS ; P. shermanii ; E. coli ; Metalloproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The local structure of the iron site in ferric superoxide dismutase from P. shermanii was analyzed by X-ray absorption spectroscopy. The metal-ligand cluster of the enzyme is found to be similar to the crystallographically investigated ferric superoxide dismutase from E. coli. At pH 6.4 the enzyme is five-fold coordinated with three histidines, an aspartate and a water molecule. The average bond lengths between the metal and the histidines are about 2.10 Å, between metal and aspartate they are about 1.86 Å and between metal and water 1.96 Å. With an increase in pH a change in the coordination number from five to six is observed both in pre-edge peak and EXAFS spectra analysis. However, the bond lengths of the ligands do not change dramatically, they are conserved for the aspartate and increase slightly to 2.13 Å for the average metal - histidine distance at pH 9.3. The observation of the increase in coordination number is correlated with a decrease in enzymatic activity which occurs in the high pH range. The zinc EXAFS spectra of P. shermanii superoxide dismutase have shown that zinc can be incorporated in the active center instead of the iron.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Mechanics of time-dependent materials 3 (1999), S. 371-393 
    ISSN: 1573-2738
    Keywords: accuracy tests ; Laser Doppler Velocimetry ; polyethylene melts ; slit die ; velocity profiles ; viscosity function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The flow behaviour of a low-density polyethylene melt is investigated in a specifically developed flow channel by means of Laser Doppler Velocimetry (LDV). The used flow channel is a slit die with a planar contraction of 14:1. The investigation of the velocity fields was performed in the steady state of flow. The optics of the LDV system as well as the used frequency analyser proved to be reliable for measurements of velocities down to 250μm/s. By adding TiO2 tracer particles to the pellets the signal quality as well as the signal frequency were improved. It is demonstrated that the Laser Doppler Velocimeter is suited to detect velocities of polymer melts with an error of a few per cent by comparing the measured volume flow rate to the directly determined mass flow rate. Using simple fluid mechanics the viscosity function is obtained by measuring only one velocity profile within the fully developed flow in the slit die. Over a wide range of shear rates the viscosity function obtained via LDV measurement corresponds with the viscosity function which was determined by the classical mass-flow-rate method. Both resulting viscosity functions were additionally checked by performing measurements with a capillary rheometer. The LDV setup described in this paper is a powerful experimental tool to investigate the flow behaviour of polymer melts. Its accuracy and the high spatial and temporal resolution opens a way to get more quantitative insight into the flow of polymer melts and to check the validity of model calculations.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Physics and chemistry of minerals 26 (1999), S. 406-414 
    ISSN: 1432-2021
    Keywords: Key words Lawsonite ; Equation of state ; X-ray diffraction ; High-pressure ; High-temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  A pressure-volume-temperature data set has been obtained for lawsonite [CaAl2Si2O7(OH)2.H2O], using synchrotron X-ray diffraction and an externally heated diamond anvil cell. Unit-cell volumes were measured to 9.4 GPa and 767 K by angle dispersive X-ray diffraction using imaging plates. Phase changes were not observed within this pressure-temperature range, and lawsonite compressed almost isotropically at constant temperature. The P-V-T data have been analyzed using a Birch- Murnaghan equation of state and a linear equation of state expressed as β=–1/V0 (∂V/∂P) T . At room temperature, the derived equation of state parameters are: K 0=124.1 (18) GPa K'0 set to 4) and β–1=142.0(24) GPa, respectively. Our results are intermediate between previously reported measurements. The high-temperature data show that the incompressibility of lawsonite decreases with increasing temperature to ∼500 K and then increases above. Hence, the second order temperature derivative of the bulk modulus is taken into account in the equation of state; a fit of the volume data yields K 0=123.9(18) GPa, (∂K/∂T)P=–0.111(3) GPa K–1, (∂2 K/∂T 2)P=0.28(6) 10–3 GPa K–2, α0=3.1(2) 10–5 K–1, assuming K'0=4.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of geodesy 73 (1999), S. 109-117 
    ISSN: 1432-1394
    Keywords: Key words. Multivariate Gauss ; Markoff model ; Eigenvalue decomposition ; Principal-component analysis ; Data reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract. Geodetic adjustment problems frequently require the solution of large systems of linear equations. An approximation method is presented based on the decomposition of the estimated covariance matrix of the observation matrix, calculated in a pre-processing step, into a system of eigenvalues and eigenvectors. Neglecting the non-dominant eigenvalues and the assigned eigenvectors, the matrix of the residuals is approximated applying the synthesis formula of principal-component analysis. Although the number of observation vectors in the multivariate Gauss–Markoff model is drastically reduced, all unknown parameters are estimated approximately. The described method is tested using a numerical example of satellite altimetry.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 93 (1996), S. 355-360 
    ISSN: 1432-2242
    Keywords: Somaclonal variation ; Cytoplasmic male sterility ; Triticale ; Regeneration ; Mitochondrial atp6 gene region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Comparative hybridization analyses of total DNA from fertile and cytoplasmic male-sterile (CMS) triticale plants which had been regenerated from embryogenic callus cultures revealed the organization and variation of the mitochondrial atp6 gene region. In order to compare different developmental phases, we analysed mitochondrial DNA (mtDNA) from both the shoots and full-grown regenerants. Somaclonal variants were identified on the basis of differences in the mtDNA from fertile and CMS triticale. Several shoots as well as all of the full-grown plants analysed showed somaclonal variation. This phenomenon could be traced back to having primarily orginated from the influence of the nuclear background, which give rise to a stoichiometric increase in a rye-specific orf25 gene copy, and a tissue culture-induced combination of fertile and CMS-specific mtDNA organization of the atp6 gene area. The latter event is probably caused by the homologous recombination of repetitive sequences that may be accompanied by selective amplifications.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 93 (1996), S. 355-360 
    ISSN: 1432-2242
    Keywords: Key words Somaclonal variation  ;  Cytoplasmic male sterility  ;  Triticale  ;  Regeneration  ;  Mitochondrial atp6 gene region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Comparative hybridization analyses of total DNA from fertile and cytoplasmic male-sterile (CMS) triticale plants which had been regenerated from embryogenic callus cultures revealed the organization and variation of the mitochondrial atp6 gene region. In order to compare different developmental phases, we analysed mitochondrial DNA (mtDNA) from both the shoots and full-grown regenerants. Somaclonal variants were identified on the basis of differences in the mtDNA from fertile and CMS triticale. Several shoots as well as all of the full-grown plants analysed showed somaclonal variation. This phenomenon could be traced back to having primarily orginated from the influence of the nuclear background, which give rise to a stoichiometric increase in a rye-specific orf25 gene copy, and a tissue culture-induced combination of fertile and CMS-specific mtDNA organization of the atp6 gene area. The latter event is probably caused by the homologous recombination of repetitive sequences that may be accompanied by selective amplifications.
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