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  • 1
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    In:  Supplement to: de Carvalho Campos, Marília; Chiessi, Cristiano Mazur; Voigt, Ines; Piola, Alberto R; Kuhnert, Henning; Mulitza, Stefan (2017): d13C decreases in the upper western South Atlantic during Heinrich Stadials 3 and 2. Climate of the Past, 13, 345-358, https://doi.org/10.5194/cp-13-345-2017
    Publication Date: 2020-01-17
    Description: Abrupt millennial-scale climate change events of the last deglaciation (i.e. Heinrich Stadial 1 and the Younger Dryas) were accompanied by marked increases in atmospheric CO2 (CO2atm) and decreases in its stable carbon isotopic ratios (d13C), i.e. d13CO2atm, presumably due to outgassing from the ocean. However, information on the preceding Heinrich Stadials during the last glacial period is scarce. Here we present d13C records from two species of planktonic foraminifera from the western South Atlantic that reveal major decreases (up to 1 per mil) during Heinrich Stadials 3 and 2. These d13C decreases are most likely related to millennialscale periods of weakening of the Atlantic meridional overturning circulation and the consequent increase (decrease) in CO2atm (d13CO2atm). We hypothesise two mechanisms that could account for the decreases observed in our records, namely strengthening of Southern Ocean deep-water ventilation and weakening of the biological pump. Additionally, we suggest that air?sea gas exchange could have contributed to the observed d13C decreases. Together with other lines of evidence, our data are consistent with the hypothesis that the CO2 added to the atmosphere during abrupt millennial-scale climate change events of the last glacial period also originated in the ocean and reached the atmosphere by outgassing. The temporal evolution of d13C during Heinrich Stadials 3 and 2 in our records is characterized by two relative minima separated by a relative maximum. This ?w structure? is also found in North Atlantic and South American records, further suggesting that such a structure is a pervasive feature of Heinrich Stadial 2 and, possibly, also Heinrich Stadial 3.
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 2
    ISSN: 1610-7403
    Keywords: Cephalotaxus ; embryogenic callus ; somatic embryogenesis ; ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Somatic embryogenesis was initiated fromCephalotaxus harringtonia (Forbes) K. Koch embryo culture. Explants consisted of embryo and megagametophyte halves both cut longitudinally. They were removed aseptically from mature seeds and grown together on a solid Murashige and Skoog modified medium supplemented with 5 mg·l −1 2,4-dichlorophenoxyacetic acid. Embryogenic cultures started from callus after three or more months on the primary medium. The embryogenic callus originated from the suspensor region of the embryo. All chromosome counts made in the cells of the embryonic structures demonstrated a diploid stage, which suggest that they originated from zygotic embryo tissue. The early stages of somatic embryogenic development were achieved,i.e., formation of small clusters consisting of an embryonal region made up of isodiametric meristematic cells. A more advanced stage was reached in some cultures in which the distal embryonal end of the embryo appeared smooth and opaque. The ultrastructural characteristics of the embryos, the two types of embryo cells, embryonal and suspensor cells, as well as their contents were similar to those already reported in the case of somatic embryogenesis of other conifers.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0885-6125
    Keywords: Robotics ; Neural Networks ; Fuzzy Controllers ; Multistrategy Learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract One of the most significant cost factors in robotics applications is the design and development of real-time robot control software. Control theory helps when linear controllers have to be developed, but it doesn't sufficiently support the generation of non-linear controllers, although in many cases (such as in compliance control), nonlinear control is essential for achieving high performance. This paper discusses how Machine Learning has been applied to the design of (non-)linear controllers. Several alternative function approximators, including Multilayer Perceptrons (MLP), Radial Basis Function Networks (RBFNs), and Fuzzy Controllers are analyzed and compared, leading to the definition of two major families: Open Field Function Approximators and Locally Receptive Field Function Approximators. It is shown that RBFNs and Fuzzy Controllers bear strong similarities, and that both have a symbolic interpretation. This characteristic allows for applying both symbolic and statistic learning algorithms to synthesize the network layout from a set of examples and, possibly, some background knowledge. Three integrated learning algorithms, two of which are original, are described and evaluated on experimental test cases. The first test case is provided by a robot KUKA IR-361 engaged into the “peg-into-hole” task, whereas the second is represented by a classical prediction task on the Mackey-Glass time series. From the experimental comparison, it appears that both Fuzzy Controllers and RBFNs synthesised from examples are excellent approximators, and that, in practice, they can be even more accurate than MLPs.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0885-6125
    Keywords: Robotics ; Neural Networks ; Fuzzy Controllers ; Multistrategy Learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract One of the most significant cost factors in robotics applications is the design and development of real-time robot control software. Control theory helps when linear controllers have to be developed, but it doesn't sufficiently support the generation of non-linear controllers, although in many cases (such as in compliance control), nonlinear control is essential for achieving high performance. This paper discusses how Machine Learning has been applied to the design of (non-)linear controllers. Several alternative function approximators, including Multilayer Perceptrons (MLP), Radial Basis Function Networks (RBFNs), and Fuzzy Controllers are analyzed and compared, leading to the definition of two major families: Open Field Function Approximators and Locally Receptive Field Function Approximators. It is shown that RBFNs and Fuzzy Controllers bear strong similarities, and that both have a symbolic interpretation. This characteristic allows for applying both symbolic and statistic learning algorithms to synthesize the network layout from a set of examples and, possibly, some background knowledge. Three integrated learning algorithms, two of which are original, are described and evaluated on experimental test cases. The first test case is provided by a robot KUKA IR-361 engaged into the peg-into-hole task, whereas the second is represented by a classical prediction task on the Mackey-Glass time series. From the experimental comparison, it appears that both Fuzzy Controllers and RBFNs synthesised from examples are excellent approximators, and that, in practice, they can be even more accurate than MLPs.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-203X
    Keywords: Key words Abscisic acid ; Bud dormancy ; Cedrus libani microcuttings ; Endogenous hormonal quantification ; Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Axillary and apical buds of in-vitro-propagated cuttings of Cedrus libani are unable to burst at 24 °C, but this inhibition was overcome at 30 °C. Here we have used cedar microcuttings to investigate whether the levels of endogenous hormones vary with bud dormancy and temperature. We analysed the levels of abscisic acid, indole-3-acetic acid, zeatin, isopentenyladenine and their major metabolites using HPLC purification and fractionation of the samples coupled to an ELISA method for hormonal quantitation involving several antibodies elicited against each hormonal family. Abscisic acid levels in microcuttings with dormant buds were higher than those in microcuttings with growing buds. At 24 °C, needles accumulated more abscisic acid than at 30 °C. In addition, when needles were removed, but growth release was achieved at 24 °C. Abscisic acid supplied at 30 °C induced the formation of dormant buds. These results suggest that abscisic acid accumulation in the needles can explain the bud dormancy of cedar microcuttings at 24 °C.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2020-01-19
    Type: Dataset
    Format: text/tab-separated-values, 199 data points
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  • 7
    Publication Date: 2020-01-19
    Type: Dataset
    Format: text/tab-separated-values, 76 data points
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  • 8
    Publication Date: 2020-01-19
    Type: Dataset
    Format: text/tab-separated-values, 79 data points
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  • 9
    Publication Date: 2020-01-19
    Type: Dataset
    Format: text/tab-separated-values, 48 data points
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  • 10
    Publication Date: 2020-01-19
    Type: Dataset
    Format: text/tab-separated-values, 49 data points
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