1,720,976 research outputs found
The response of thermocline ventilation to variability at the ocean surface from observations and offline tracer modeling
Get PDFThesis (Ph.D.)--University of Washington, 2016-03Variability in oceanic ventilation can arise from either changes at the surface of the ocean or the ocean interior. Four studies are presented which advance our understanding on how these changes can be diagnosed in both observational and modeling contexts. Chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF6) have been used extensively to infer transit time distributions (TTDs) and ventilation ages in the ocean. An offline tracer model (Offtrac) is combined with a simple model of gas exchange to simulate the mixed layer saturations of CFC-11, CFC-12, and SF6. The large wintertime undersaturations of these tracers arise from the increase in solubility due to the cooling of the mixed layer and also from the entrainment of relatively tracer-poor waters as the mixed layer deepens. In the mode waters of the North Pacific, this can cause a bias TTD mean ages of up to 24%. The Antarctic Circumpolar Current (ACC) is a strong dynamical feature in the Southern Ocean which transports water around the entirety of the Antarctic continent. Monte-Carlo simulations of a meandering Gaussian jet model in conjunction with distributions of sea level anomaly from 1992 to 2014 are used to determine the mean position and width of the fronts that form the boundaries of the ACC. The mean position of these fronts largely follow the underlying topography. Significant internannual variability in the location of the fronts was uncorrelated to changes in the Southern Annular Mode (SAM). Offtrac is used to simulate CFCs, SF6, oxygen, ideal age, and transit time distributions using a boundary impulse response technique (TTD-BIR). The output from these simulations are used to evaluate how well tracers can constrain the timescales of oceanic ventilation. The inverse Gaussian solution to the 1d transport equation is shown to be a reasonable approximation to the TTD-BIR within the ventilated thermocline of the subtropical gyres, but a poor approximation in regions with strong gradients in age. 1d TTDs constrained by modeled CFC-12 and SF6 have a strong bias towards diffusively dominated transport. By comparing variability in oxygen and tracer-inferred TTD mean ages to changes in ideal age, guidelines are developed as to where observations of these tracers may robustly diagnose changes in ventilation. The effect of how variability of a tracer at the surface maps to changes in the oceanic interior is examined using an analytic Fourier transform of the 1d TTD. The magnitude and phase of the Fourier coefficients of the 1d TTD demonstrate that interior variability is a result of ventilation behaving like a low-pass filter with nonlinear phase response applied to a time-varying surface boundary condition. Typical values of the parameters of the filter for the thermocline suggest that primarily the low-frequency (>5 years) part of the time-varying boundary condition are likely to observed within the interior. Both climatological and hindcast adjoint TTDs are calculated in Offtrac to understand variability of the formation of North Pacific Mode Water (NPMW) and South Indian Ocean Subantarctic Mode Water (ISAMW). Using volume fraction (Vf) and mean ages calculated from these adjoint TTDs, NPMW is found to be formed within one region of the North Pacific, whereas ISAMW likely has at least two formation regions, one within the Indian Ocean and another southwest of Australia. Empirical orthogonal function analysis shows that about 54% of ISAMW Vf variability is captured by a mode, uncorrelated to SAM (p<0.1), with a 30-year oscillation between the two climatological formation regions. For NPMW, 69% of the variability is explained by a meridional mode centered around 35N in the central North Pacific that is significantly correlated (p<0.05) with the Pacific Decadal Oscillation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Wahrnehmung und Steuerung von sozialökonomischem Wandel in Deutschland 1945-2000
Get PDFIn beiden deutschen Staaten wurden seit ihrer Gründung politische Anstrengungen unternommen, um den ökonomischen Strukturwandel in seinem Verlauf und seinen Wirkungen zu lenken. Trotz unterschiedlicher Rahmenbedingungen gestalteten sich die Problemkonstellationen ähnlich: Einseitige Branchenstrukturen und räumliche Ungleichgewichte sollten ausgeglichen, Arbeitsplätze bereitgestellt und die Infrastruktur entwickelt werden. Der Sammelband fragt nach Wahrnehmungen und Deutungen strukturpolitischer Herausforderungen sowie nach den Trägern und Mitgestaltern des strukturellen Wandels in West- und Ostdeutschland in der zweiten Hälfte des 20. Jahrhunderts. Dabei werden Möglichkeiten und Grenzen der Steuerungsansätze sowohl im nationalen Kontext analysiert als auch mit Blick auf kollektive Akteure und Betroffene wie Länderregierungen und Kommunen, Branchen und Unternehmen, Gewerkschaften und Arbeitnehmer
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Skandal!? Stadtgeschichten aus Marburg im 20. Jahrhundert
Get PDFSkandale bieten mit ihren schlüpfrigen Details, heftigen Emotionsausbrüchen und überkommenen Moralvorstellungen ein spannendes und innovatives Forschungsfeld für die Stadtgeschichte. Die Beiträger*innen des Bandes widmen sich am Beispiel Marburgs diesem politischen, sozialen und medialen Phänomen aus einer interdisziplinären Perspektive. Sie verstehen Skandale dabei als öffentliche Normkonflikte sowie gesellschaftliche und politische Selbstreinigungsmechanismen, die zum Alltag moderner Gesellschaften gehören. Ihre Analysen zu den Funktionsweisen, Verlaufsmustern und Auswirkungen machen deutlich: Die moderne Stadt- und Skandalgeschichte gehören zusammen
(Un-)Sicherheit und Stadtnacht : Ansätze, Konzepte und historisch-empirische Annäherungen
Get PDFZu den Standardstatements des herkömmlichen Narratives über die Stadtnacht gehören besondere Gefährdungen und Unsicherheiten, von denen vor allem (junge) Frauen betroffen seien; diese Betroffenheit reiche bis hin zum Ausschluss von Frauen aus der Stadtnacht. Im vorliegenden Beitrag wird diese Sichtweise jedoch hinterfragt. Als illustrativer Einstieg in diese Diskussion dienen einige Hinweise, die dem bis dato verfügbaren Korpus neuerer historischer und sozialwissenschaftlicher Forschungsergebnisse entnommen sind
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
„Saxa loquuntur, homines tacent?“. Holocaust-Denkmäler als geschichtskulturelle Herausforderung.
No full textFestschrift für Wolfgang Jacobmeyer zum 65. Geburtsta
- …
