197,805 research outputs found
Biotic responses to rapid climatic changes
No full textQualitative and quantitative changes in fossil flora and fauna have been used in many studies to infer climatic change. Here we ask a different question: how do flora and fauna respond to climatic changes such as rapid warming or cooling? As an independent proxy for paleotemperature we take the ratio of oxygen isotopes in biogenically precipitated lake marl and in ostracod shells. This introductory paper describes the project design and the five sites on an altitudinal transect from 600 m to about 2300 m asl in the western Swiss Alps. As cases of climatic cooling and warming we use the beginning and end of the Younger Dryas as major changes, and the Gerzensee and Preboreal oscillations as minor changes. At the two sites of Gerzensee and Leysin these changes are recorded in stable-isotope ratios, and there the time scales can be derived by correlations to the GRIP ice core (Schwander et al., 2000 and von Grafenstein et al., 2000). Biotic responses to climate changes are treated in individual papers using pollen (Wick, 2000), plant macrofossils (Tobolski and Ammann, 2000), and remains of chironomids (Brooks, 2000), beetles and other insects (Lemdahl, 2000), and chydorid Cladocera (Hofmann, 2000). They are followed by a synthesis focusing on quantification of biotic responses (Ammann et al., 2000).
In addition, a reconstruction of summer temperatures for the Allerød and the Younger Dryas at Gerzensee is provided by Lotter et al. (2000)
Athanase III Patellaros, patriarche de Constantinople, ex-catbolique et saint russe
No full textAmmann A. M. Athanase III Patellaros, patriarche de Constantinople, ex-catbolique et saint russe. In: Revue des études slaves, tome 28, fascicule 1-4, 1951. pp. 7-16
Today’s vegetation and woody flora
No full textConsidered over long time scales, today's vegetation is only the last realization of a dynamic process and not a static concept. On the one hand, knowledge of modern vegetation is essential for our understanding of vegetation history, on the other hand, considering this history allows a deeper understanding of the present vegetation. In Europe this comparison is made difficult because of the human impact on the environment over millennia: what we observe as the modern plant cover is only rarely the end product of a natural vegetation history.
A distinction was often made between ‘modern natural vegetation’ (plant cover without any human impact) and ‘modern potential natural vegetation’ (plant cover including human impact but as it would be after the cessation of this influence). Both are concepts based on soils, climate and biogeography, but they remain constructions with large uncertainties (Tüxen, 1956; Frenzel, 1968; Neuhäusl, 1991; Bohn et al., 2003; Birks, 2019).
For our purpose a map of the modern potential natural vegetation on a small scale will be sufficient showing the ‘zonal vegetation’ that depends on large-scale factors such as temperature and precipitation and that omits the ‘azonal vegetation’ depending on edaphic conditions (for example riparian forests, mires, halophytic habitats). Moreover, the elevational belts of mountain systems cannot be fully shown on this scale. A higher spatial resolution can be found in Ozenda (1979) and Bohn et al. (2003). As an overview we can distinguish five vegetation zones (biomes) in Europe:
• The arctic and alpine zone with treeless dwarf shrub, meadow or tall herb vegetation (A)
• The boreal zone with a dominance of conifers (B)
• The temperate zone with mainly forests of deciduous trees (T)
• The Mediterranean zone with co-dominance (mesomediterranean) or dominance (thermomediterranean) of evergreen broadleaved trees and shrubs (M)
• The Pannonic-Pontic-Anatolian zone with forest steppes, steppes and semi-deserts (P) Most limits are spatially not clearly delimited and this can be expressed in terms such as ‘forest- tundra’ or ‘subarctic’ – belts that can be very broad for example in north-west Russia
Verba et locutiones oratoriae decerptae ex libris oratoriis M. T. Ciceronis : quibus accedunt locutiones dialecticae, ac forenses, ex iisdem libris Ciceronis collectae
No full textopera Ammiani professoris TiguriniBogensignaturen: a-e
Evaluation of Antenna Types for RF Breast Cancer Imaging using 2-Layer Planar Tissue Model
No full textComparison of Non-Coherent Linear Breast Cancer Detection Algorithms Applied to a 2-D Numerical Breast Model
No full textA comparative analysis of an imaging method based on a multifrequency Multiple Signal Classification (MUSIC) approach against two common linear detection algorithms based on noncoherent migration is made. The different techniques are tested using synthetic data generated through CST Microwave Studio and a phantom developed from MRI scans of a mostly fat breast. The multifrequency MUSIC approach shows an overall superior performance compared to the noncoherent techniques. This letter reports that this highly performing algorithm does not require any antenna calibration or phase response estimation and allows the use of efficient and complex antenna geometries without difficult algorithm redefinitions
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
Freiwilligkeit als soziales Kapital der Gesellschaft. Makrosoziologische Untersuchungen für die Schweizer Kantone
No full textReferate und Zusammenfassungen der 5. Tagung der Europäischen Freiwilligenuniversität vom 30. bis 31.5.2005 in Luzern.
Verschiedene gesellschaftliche Bereiche, die traditionell mit unbezahlter Arbeit abgedeckt worden sind, gehen in vermehrtem Ausmass in den Bereich der bezahlten Arbeit über. Dabei wird in der Regel mit der Notwendigkeit von vermehrter Professionalisierung argumentiert. Generell unterliegen immer grössere Bereiche der Lebenszusammenhänge einem Monetarisierungsprozess. Sie werden dem Markt erschlossen und werden so Gegegenstand von Erwerbsarbeit. Es hat den Anschein, dass sich diese Entwicklung in den letzten Jahrzehnten beschleunigt hat. Die Europäische Freiwilligenuniversität (EFU) 2005 Luzern hat sich in Referaten und Workshops mit Fragestellungen auseinandergesetzt, die sich aus dieser Entwicklung ergeben: Dem Stellenwert der Freiwilligenarbeit in der heutigen Gesellschaft, der Suche nach Modellen und Konzepten, die sich mit der angedeuteten Entwicklung auseinandersetzen, der Bewältigung der sich daraus ergebenden Spannungsfelder und Probleme. Das Buch enthält die Beiträge von Markus Freitag, Michael Nollert, Theo Wehner, Marianne Resch, Heidi Schelbert, Martina Ziegerer, Agnes Fritze, Jürgen Stremlow, Heinz Jannig, Gisela Jacob, Gerd Placke, Sandro Cattacin, Patrick Kenis, Annette Zimmer u. a. m
Bananes et ananas : production et commerce en Guinée française / par Yves Henry,... ; avec la collaboration de M. P. Ammann,... et de M. P. Teissonnier,...
No full textCollection : Bibliothèque d'agriculture colonialeCollection : Bibliothèque d'agriculture colonialeAppartient à l’ensemble documentaire : NmBA001Appartient à l’ensemble documentaire : NmBA003Contient une table des matièresAvec mode text
Field Penetration in MRI-based Breast Models: a Numerical Investigation
No full textThe use of reliable computational tools is fundamental to investigate different aspects of microwave breast cancer imaging. From the development of high-definition and realistic numerical breast models, different coupling mechanisms and the reaction of different tissues to microwave signals can be characterized. In this paper, field penetration inside four numerical breast phantoms with varying adipose content is evaluated in the frequency range 0.5 - 10 GHz across sagittal cuts
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