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Institution

Vienna University of Technology

EducationVienna, Austria
About: Vienna University of Technology is a education organization based out in Vienna, Austria. It is known for research contribution in the topics: Laser & Cloud computing. The organization has 16723 authors who have published 49341 publications receiving 1302168 citations.


Papers
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Journal ArticleDOI
TL;DR: The authors in this paper provide an overview of what the Millennium Ecosystem Assessment (MA) call "indirect and direct drivers" of change in ecosystem services at a global level.
Abstract: This paper provides an overview of what the Millennium Ecosystem Assessment (MA) call "indirect and direct drivers" of change in ecosystem services at a global level. The MA definition of a driver is any natural or human-induced factor that directly or indirectly causes a change in an ecosystem. A direct driver unequivocally influences ecosystem processes. An indirect driver operates more diffusely by altering one or more direct drivers. Global driving forces are categorized as demographic, economic, sociopolitical, cultural and religious, scientific and technological, and physical and biological. Drivers in all categories other than physical and biological are considered indirect. Important direct drivers include changes in climate, plant nutrient use, land conversion, and diseases and invasive species. This paper does not discuss natural drivers such as climate variability, extreme weather events, or volcanic eruptions.

351 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a survey of water resources engineering at the International Institute of Hydraulic and Water Resources Engineering, Vienna University of Technology, Karlsplatz 13, A-1040 Vienna, Austria.
Abstract: 1 Institute of Hydraulic and Water Resources Engineering, Vienna University of Technology, Karlsplatz 13, A-1040 Vienna, Austria 2 UMR HydroSciences Montpellier, France 3 UNESCO Division of Water Sciences, Paris, France 4 University of Vienna, Austria 5 USDA-ARS-SWRC, Tucson, AZ, USA 6 FIMCM-ESPOL, Campus Gustavo Galindo, Guayaquil, Ecuador 7 GeoForschungsZentrum Potsdam, Germany 8 CSIRO Land and Water, Glen Osmond, Australia 9 Slovak University of Technology, Bratislava, Slovakia

350 citations

Journal ArticleDOI
TL;DR: In this paper, 14C was determined in elemental carbon (EC) and different organic carbon (OC) fractions from ambient urban aerosols with aerodynamic diameter <10 μm collected in Zurich (Switzerland).
Abstract: [1] Many open questions exist about the importance of different sources of carbonaceous aerosol, which is a substantial contributor to the global aerosol budget and, therefore, to climate change and human mortality. In this work, 14C was determined in elemental carbon (EC) and different organic carbon (OC) fractions from ambient urban aerosols with aerodynamic diameter <10 μm collected in Zurich (Switzerland). This enabled a more detailed source attribution of the carbonaceous aerosol mass than is possible with other currently available methods. The three major sources, fossil fuel, wood combustion (both anthropogenic emissions), and biogenic emissions, were quantified, making specific regulatory air quality management measures possible. EC originates nearly exclusively from fossil fuel usage during summer, whereas biomass-burning emissions become substantial during winter with ∼25%, even though this source contributes only marginally to the local energy consumption. For OC, biogenic sources are dominant in summer with ∼60%, where secondary organic aerosol prevails. Wood combustion accounts for up to ∼41% of OC in winter. Fossil fuels represent ∼30% of OC throughout the year.

350 citations

Journal ArticleDOI
TL;DR: Examination of the growth behavior of the different mutant strains of the H. jecorina genome pointed to the strongly reduced ability of the xyr1 deletion strain to utilize d-xylose and xylan, and transcriptional regulation of the major hydrolytic enzyme-encoding genes xyn1 and xyn2, cbh1 and cbh2, and egl1 (endoglucanase 1 and 2) is strictly dependent on Xyr1.
Abstract: Hypocrea jecorina (anamorph Trichoderma reesei) is a fungus of noteworthy industrial importance, mainly because of its employment in both fermentative production of native extracellular enzymes and heterologous protein production. Hydrolases secreted by this fungus have achieved broad areas of applications, e.g., in pulp and paper (4, 35, 50), food and feed (9, 27, 49), and textile (23, 26, 36) industries. The set of hydrolytic enzymes produced by H. jecorina comprises two main cellobiohydrolases, CBHI and CBHII (EC 3.2.1.91) (43); endo-β-1,4-glucanases EGI to EGV (EC 3.2.1.4) (37); 1,4-β-glucosidases BGLI and BGLII (EC 3.2.1.21) (8, 40); two major specific endo-β-1,4-xylanases, XYNI and XYNII (EC 3.2.1.8) (45); and one β-xylosidase, BXLI (EC 3.2.1.37) (17), to mention only the best characterized. This set of hydrolases is synergistically working together to attain a complete degradation of biopolymeric substrates, of which cellulose and xylan are predominant. In this particular breakdown process, these enzymes cause hydrolysis to smaller, soluble oligo- and monosaccharides which finally either act directly as low-molecular-weight inducer substances (e.g., xylobiose and xylose) (29, 53) or are converted to their respective inducers (e.g., sophorose) via the transglycosylation activity of some of these enzymes (46). Whereas in Aspergillus spp. the xylanolytic and cellulolytic systems are strictly coregulated via the inducer xylose (10, 15), enzymes participating in the respective T. reesei hydrolytic systems are not. Their differential expression levels have been reported in several studies. Briefly summarizing these findings, all discussed hydrolytic genes are inducible by their respective degradation and/or transglycosylation products of xylan and/or cellulose, e.g., the xyn1 (xylanase 1-encoding) gene is inducible by xylose (30), the xyn2 (xylanase 2-encoding) gene by xylobiose and sophorose (53), and the bxl1 (β-xylosidase 1-encoding) gene by xylobiose (33); cellulases such as the cbh1 (cellobiohydrolase 1-encoding) gene, the cbh2 (cellobiohydrolase 2-encoding) gene, and the egl1 (endoglucanase 1-encoding) gene (20); and the bgl1 (β-glucosidase 1-encoding) gene (8) and the bgl2 (β-glucosidase 2-encoding) gene (40) by soph-orose. We recently reported that during xylose-mediated induction of xyn1, Xyr1 (xylanase regulator 1) plays a main role in H. jecorina (38). Xyr1 is a zinc binuclear cluster protein binding to a GGCTAA motif arranged as an inverted repeat in the xyn1 promoter (38), closely resembling the consensus sequence for binding of the Aspergillus niger XlnR transactivator (48). XlnR is not only a central regulator protein responsible for activation of more than 10 genes involved in degradation of xylan and cellulose, it also contributes to the regulation of d-xylose metabolism (10, 15, 47). Ancillary to Xyr1/XlnR-mediated induction, the carbon catabolite repressor Cre1/A has for both organisms been described as a wide domain repressor of particular hydrolase-encoding genes (6, 7, 21, 30). In T. reesei, only some of the major hydrolases, namely cbh1 and xyn1, are under direct Cre1 control (21, 30), whereas other hydrolytic genes such as cbh2, xyn2, and bgl1 are not Cre1 regulation dependent (31, 33). In addition, the isolation of the two transcription factors Ace1 and Ace2, potentially involved in the regulation of hydrolase formation in H. jecorina, has been reported (2, 39). While the previously described repressor Ace1 (1) was proven to directly antagonize Xyr1 function by competing for one of its binding sites in the xyn1 promoter (38), deletion of ace2 was demonstrated to clearly reduce expression levels of the main cellulase genes and of the xyn2 gene cultivated on cellulose but did not affect induction on sophorose (2). A more detailed study revealed that Ace2 contacts the xylanase-activating element XAE (essential for xyn2 expression) in the xyn2 promoter (52) but is not involved in xyn1 transcription (2, 38). Up until now, no mechanisms involving respective orthologous regulators have been identified in the expression of Aspergillus hydrolases. In this study, we report the deletion of xyr1 from the H. jecorina genome. Strikingly reduced growth on d-xylose and restricted utilization of xylan by the xyr1 deletion strain could be observed compared to that of the wild type. Consequently, we identified Xyr1 as a general and essential transcriptional activator of not only xyn1 but also xyn2, cbh1, cbh2, and egl1 gene transcription. Furthermore, Xyr1 was demonstrated to strictly control xylanolytic as well as cellulolytic enzyme formation under inducing and noninducing conditions in H. jecorina. Moreover, Xyr1 could be shown to regulate the gene expression of at least some inducer-providing enzymes, e.g., BGLI and BXLI. Finally, we have proven the involvement of Xyr1 in d-xylose metabolism, namely, its strong impact on the expression of d-xylose reductase activity. Summarizing, we revealed Xyr1 to govern the expression of the xylanolytic and cellulolytic enzyme system as well as d-xylose metabolism in H. jecorina.

350 citations

Journal ArticleDOI
TL;DR: A negative answer is given by proving the NP-completeness of the problem whether for each constant k it can be determined in polynomial time if a query has query-width at most k, and the new concept of hypertree decomposition of a query and the corresponding notion ofhypertree-width is introduced.

350 citations


Authors

Showing all 16934 results

NameH-indexPapersCitations
Krzysztof Matyjaszewski1691431128585
Wolfgang Wagner1562342123391
Marco Zanetti1451439104610
Sridhara Dasu1401675103185
Duncan Carlsmith1381660103642
Ulrich Heintz136168899829
Matthew Herndon133173297466
Frank Würthwein133158494613
Alain Hervé132127987763
Manfred Jeitler132127889645
David Taylor131246993220
Roberto Covarelli131151689981
Patricia McBride129123081787
David Smith1292184100917
Lindsey Gray129117081317
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023171
2022379
20212,527
20202,811
20192,846
20182,650