2,925 research outputs found
A Transfer Report on the Development of a Framework to Evaluate Search Interfaces for their Support of Different User Types and Search Tactics
No full textAs the understanding of search systems, user needs and seeking strategies is developing, the design of search user interfaces is evolving to support more complicated and exploratory forms of search. With the design of new search features that enable these richer modes of exploration, comes the need to better understand the support they provide. In this report a new evaluation framework is presented that analyses search features for how they a) contribute to an overall interface, b) allow users to carry out different search tactics, and c) support different types of users and their needs. The novel contributions of the framework improve on some of the limitations of typical user studies, and allow search systems to be systematically analysed in much more detail and in much less time. The presented evaluation framework is then validated in three ways. First the validity of the models used as the building blocks of the framework are investigated through related work. Second the method of integrating these building-block models is validated and strengthened by consensus of expert opinion. Third, the overall approach is validated by comparing its analyses to the results of previously carried out user studies. The validation process has shown both the value of the framework and identified areas of future work that should be addressed for the framework to be completed. This report concludes with the set of contributions that the framework makes, and why the remaining work will be challenging, but critical to the final design
Die Bestimmung von Forschungsthemen in Max-Planck-Instituten im Spannungsfeld wissenschaftlicher und außerwissenschaftlicher Interessen: Ein Forschungsbericht
No full textHeute steht im Zentrum der öffentlichen Diskussion die Frage, wie sich der praktische Nutzen der Wissenschaft für Wirtschaft und Gesellschaft maximieren lässt. Die empirische Untersuchung, deren Ergebnisse in diesem Bericht dargestellt werden, geht von der umgekehrten Frage aus: Wie beeinflusst die gesellschaftliche Einbettung von Forschungseinrichtungen, vermittelt über die Auswahl von Forschungsthemen, die Entwicklung der Wissenschaft? Gegenstand der Untersuchung waren Institute der Max-Planck-Gesellschaft. Zunächst wurden statistische Daten über die Außenbeziehungen von Max-Planck-Instituten, die die Generalverwaltung der MPG zur Verfügung stellte, analysiert. In den Jahren 1999 und 2000 führte die Verfasserin Interviews mit den Direktoren ausgewählter Institute aller drei Sektionen der MPG durch und wertete verfügbare schriftliche Unterlagen über ihre Forschungstätigkeit aus. Der Bericht schildert exemplarisch den Prozess der Bestimmung von Forschungsthemen in Max-Planck-Instituten und wie dieser vom institutionellen Rahmen, von den Beziehungen zur wissenschaftlichen Fachwelt und von den Beziehungen zu verschiedenen Praxisfeldern beeinflusst wird. In Abhängigkeit von der Eigenart der Forschungsfelder, in denen ein Institut tätig ist, und dessen potentieller Praxisrelevanz ergeben sich verschiedene Muster von Außenbeziehungen, in denen je nachdem die Beziehungen zur Praxis oder die Beziehungen zur wissenschaftlichen Fachwelt größere Bedeutung für die Themenwahl haben.Today the usefulness of science for society and economy is the focal issue in science policy. This report presents the results of an empirical study starting from a different perspective, i.e. how the societal embeddedness of research institutions affects the choice of research topics and thus, in the aggregate, the direction of scientific development. In this study, Max Planck institutes were the object of investigation. In a first phase, statistical data about the external relations of Max Planck institutes were analyzed. In 1999 and 2000, this was followed by a series of interviews which the author conducted with the directors of selected institutes, supplemented by the analysis of written documents. The report shows in an exemplary fashion how the process of choosing research topics in Max Planck institutes is affected by their institutional shape, their interaction with different fields of societal praxis, and their relations to the national and international scientific communities. The resulting patterns of external relations and the relative importance of links with the scientific community and of links with fields of (e.g. industrial, medical) praxis differ according to the potential applicability of given research fields
Identification of a chlorodibenzo-p-dioxin dechlorinating Dehalococcoides mccartyi by stable isotope probing
No full textPolychlorinated dibenzo-p-dioxins (PCDDs) are released into the environment from a variety of both anthropogenic and natural sources. While highly chlorinated dibenzo-p-dioxins are persistent under oxic conditions, in anoxic environments these organohalogens can be reductively dechlorinated to less chlorinated compounds that are then more amenable to subsequent aerobic degradation. Identifying the microorganisms responsible for dechlorination is an important step in developing bioremediation approaches. In this study, we demonstrated the use of a DNA-stable isotope probing (SIP) approach to identify the bacteria active in dechlorination of PCDDs in river sediments, with 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TeCDD) as a model. In addition, pyrosequencing of reverse transcribed 16S rRNA of TeCDD dechlorinating enrichment cultures was used to reveal active members of the bacterial community. A set of operational taxonomic units (OTUs) responded positively to the addition of 1,2,3,4-TeCDD in SIP microcosms assimilating 13C-acetate as the carbon source. Analysis of bacterial community profiles of the 13C labeled heavy DNA fraction revealed that an OTU corresponding to Dehalococcoides mccartyi accounted for a significantly greater abundance in cultures amended with 1,2,3,4-TeCDD than in cultures without 1,2,3,4-TeCDD. This implies the involvement of this Dehalococcoides mccartyi strain in the reductive dechlorination of 1,2,3,4-TeCDD, and suggests the applicability of SIP for a robust assessment of the bioremediation potential of organohalogen contaminated sites.Peer reviewe
Optimal solution of the nearest correlation matrix problem by minimization of the maximum norm
No full textThe nearest correlation matrix problem is to find a valid (positive semidefinite) correlation matrix, R(m,m), that is nearest to a given invalid (negative semidefinite) or pseudo-correlation matrix, Q(m,m); m larger than 2. In the literature on this problem, 'nearest' is invariably defined in the sense of the least Frobenius norm. Research works of Rebonato and Jaeckel (1999), Higham (2002), Anjos et al. (2003), Grubisic and Pietersz (2004), Pietersz, and Groenen (2004), etc. use Frobenius norm explicitly or implicitly. However, it is not necessary to define 'nearest' in this conventional sense. The thrust of this paper is to define 'nearest' in the sense of the least maximum norm (LMN) of the deviation matrix (R-Q), and to obtain R nearest to Q. The LMN provides the overall minimum range of deviation of the elements of R from those of Q. We also append a computer program (source codes in FORTRAN) to find the LMN R from a given Q. Presently we use the random walk search method for optimization. However, we suggest that more efficient methods based on the Genetic algorithms may replace the random walk algorithm of optimization.Nearest correlation matrix problem; Frobenius norm; maximum norm; LMN correlation matrix; positive semidefinite; negative semidefinite; positive definite; random walk algorithm; Genetic algorithm; computer program; source codes; FORTRAN; simulation
Arctic tundra soil bacterial communities active at subzero temperatures detected by stable isotope probing
No full textArctic soils store vast amounts of carbon and are subject to intense climate change. While effects of thaw on the composition and activities of Arctic tundra microorganisms has been examined extensively, little is known about the consequences of temperature fluctuations within the subzero range in seasonally frozen or permafrost soils. This study identified tundra soil bacteria active at subzero temperatures using stable isotope probing (SIP). Soils from Kilpisjärvi, Finland were amended with 13C-cellobiose and incubated at 0, -4, and -16°C for up to 40 weeks. 16S rRNA gene sequence analysis of 13C-labelled DNA revealed distinct subzero-active bacterial taxa. The SIP experiments demonstrated that diverse bacteria, including members of Candidatus Saccharibacteria, Melioribacteraceae, Verrucomicrobiaceae, Burkholderiaceae, Acetobacteraceae, Armatimonadaceae, and Planctomycetaceae were capable of synthesizing 13C-DNA at subzero temperatures. Differences in subzero temperature optima were observed, for example with members of Oxalobacteraceae and Rhizobiaceae found to be more active at 0°C than at -4°C or -16°C, whereas Melioribacteriaceae were active at all subzero temperatures tested. Phylogeny of 13C-labelled 16S rRNA genes from the Melioribacteriaceae, Verrucomicrobiaceae, and Candidatus Saccharibacteria suggested that these taxa formed subzero-active clusters closely related to members from other cryo-environments. This study demonstrates that subzero temperatures impact active bacterial community composition and activity which may influence biogeochemical cycles.Peer reviewe
Le nozioni di "lotta" e "selezione" nei Soziologische Grundbegriffe di Max Weber
No full textThe study gives an analysis of the ideal types of «conflict» and «selection» in Max Weber???s interpretive sociology. The author shows that Weber???s sociology distinguishes sharply the conflict from the selection (understood both as «social selection» than as «biological selection»). But the author also highlights the interest of Weber for the actual connection that exists between the two phenomena and that influences the socio-historical processes
A model-independent Dalitz plot analysis of B±→DK± with D→K0Sh+h− (h=π,K) decays and constraints on the CKM angle γ
No full textA binned Dalitz plot analysis of B ±→DK ± decays, with D→KS0π+π- and D→KS0K+K-, is performed to measure the CP-violating observables x ± and y ± which are sensitive to the CKM angle γ. The analysis exploits 1.0 fb -1 of data collected by the LHCb experiment. The study makes no model-based assumption on the variation of the strong phase of the D decay amplitude over the Dalitz plot, but uses measurements of this quantity from CLEO-c as input. The values of the parameters are found to be x -=(0.0±4.3±1.5±0.6)×10 -2, y -=(2.7±5.2±0.8±2.3)×10 -2, x +=(-10.3±4.5±1.8±1.4)×10 -2 and y +=(-0.9±3.7±0.8±3.0)×10 -2. The first, second, and third uncertainties are the statistical, the experimental systematic, and the error associated with the precision of the strong-phase parameters measured at CLEO-c, respectively. These results correspond to γ=(44-38+43)°, with a second solution at γ→γ+180°, and r B=0.07±0.04, where r B is the ratio between the suppressed and favoured B decay amplitudes
Generalized and Customizable Sets in R
No full textWe present data structures and algorithms for sets and some generalizations thereof (fuzzy sets, multisets, and fuzzy multisets) available for R through the sets package. Fuzzy (multi-)sets are based on dynamically bound fuzzy logic families. Further extensions include user-definable iterators and matching functions. (author´s abstract)Series: Research Report Series / Department of Statistics and Mathematic
De Max-Planck medaille
No full textDe Max-Planck-Medaille is een onderscheiding die sinds 1929 jaarlijks wordt uitgereikt door de toentertijd grootste vereniging van natuurkundigen ter wereld: de Deutsche Physikalische Gesellschaft. Het is als het ware de Nobelprijs voor de theoretische natuurkunde, volgens de natuurkundigen zelf. In 1962 werd deze prestigieuze prijs toegekend aan de Delftse hoogleraar in de theoretische natuurkunde, tevens Rector Magnificus van de TH Delft: Ralph Kronig (1904-1995). De medaille is, samen met een klein persoonlijk archief, in 2016 door de familie geschonken aan de TU Delft.Library Research Service
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