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Search Results: 1 - 10 of 6156 matches for " Carlo Thiel3 "
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Central energy metabolism remains robust in acute steatotic hepatocytes challenged by a high free fatty acid load
Jens Niklas1,*, Anne Bonin1, Stefanie Mangin1, Joachim Bucher1, Stephanie Kopacz2, Madlen Matz-Soja 3, Carlo Thiel3, Rolf Gebhardt3, Ute Hofmann2 & Klaus Mauch1
BMB Reports , 2012,
Abstract: Overnutrition is one of the major causes of non-alcoholic fattyliver disease (NAFLD). NAFLD is characterized by an accumulationof lipids (triglycerides) in hepatocytes and is often accompaniedby high plasma levels of free fatty acids (FFA). Inthis study, we compared the energy metabolism in acute steatoticand non-steatotic primary mouse hepatocytes. Acute steatosiswas induced by pre-incubation with high concentrationsof oleate and palmitate. Labeling experiments were conductedusing [U-13C5,U-15N2] glutamine. Metabolite concentrationsand mass isotopomer distributions of intracellular metaboliteswere measured and applied for metabolic flux estimation usingtransient 13C metabolic flux analysis. FFAs were efficientlytaken up and almost completely incorporated into triglycerides(TAGs). In spite of high FFA uptake rates and the high synthesisrate of TAGs, central energy metabolism was not significantlychanged in acute steatotic cells. Fatty acid β-oxidationdoes not significantly contribute to the detoxification ofFFAs under the applied conditions.
A Methodology to Assess the Safety of Aircraft Operations When Aerodrome Obstacle Standards Cannot Be Met  [PDF]
Hartmut Fricke, Christoph Thiel
Open Journal of Applied Sciences (OJAppS) , 2015, DOI: 10.4236/ojapps.2015.52007
Abstract: When Aerodrome Obstacle Standards cannot be met as a result of urban or technical development, an aeronautical study can be carried out with the permission of EASA, in conjunction with ICAO, to prove how aircrafts can achieve an equivalent level of safety. However currently, no detailed guidance for this procedure exists. This paper proposes such a safety assessment methodology in order to value obstacle clearance violations around airports. This method has already been applied to a safety case at Frankfurt Airport where a tower elevating 4 km out of threshold 25R severely violates obstacle limitation surfaces. The model data refers to a take-off and landing performance model (TLPM) computing precisely aircraft trajectories for both standard and engine out conditions at ground proximity. The generated tracks are used to estimate collision risk incrementally considering EASA/FAA, EU-OPS & ICAO clearance criteria. Normal operations are assessed with a probabilistic analysis of empirical take-off/landing track data generating the local actual navigation performance (ANP) on site. The ANP shows integration to collision risk for an aircraft with any obstacle. The obstacle is tested for clearance within a “5-step-plan” against all performance requirements for landing climb and take-off climb. The methodology thereby delivers a comprehensive risk picture: The presented safety case for Frankfurt Airport showed an equivalent safety level despite the violation of standards. The collision risk during both normal and degraded performance operations was still found to be within ICAO Collision Risk Model (CRM) limits, requiring only limited risk mitigation measures. The presented work should complement ICAO Doc 9774 Appendix 3.
Alternative Nitrogenases in Anabaena variabilis: The Role of Molybdate and Vanadate in Nitrogenase Gene  [PDF]
Teresa Thiel, Brenda S. Pratte
Advances in Microbiology (AiM) , 2013, DOI: 10.4236/aim.2013.36A011
Abstract: Anabaena variabilis ATCC 29413 has two distinct nitrogenases that function in heterocysts, a conventional Mo-nitrogenase and an alternative V-nitrogenase. Synthesis of these two enzymes was repressed in cells growing with a source of fixed nitrogen, such as ammonium; however, the V-nitrogenase was also repressed by Mo. Expression of the V-nitrogenase which was not affected by V and expression of the Mo-nitrogenase was not affected by the presence or absence of either Mo or V. In the absence of both Mo and V in an environment lacking fixed nitrogen, cells became starved for both metals; however, low levels of nitrogen fixation and slow growth persisted. A mutant lacking the V-nitrogenase was still able to grow very slowly in Mo-and V-free medium; however, loss of the Mo-nitrogenase in a nifDK1 mutant abolished the residual growth, suggesting that only the Mo-nitrogenase functioned under these conditions to support slow growth. The addition of vanadate, molybdate, or tungstate, which is transported by the molybdate transporter, to cells starved for these metals resulted in an increase in nitrogenase activity within two hours after the addition of the metal and this increase required new protein synthesis. While tungstate functioned about as well as vanadate in supporting acetylene reduction, the cells were not able to grow any better with tungstate than with no added metal. A mutant lacking the V-nitrogenase showed no increase in nitrogenase activity upon addition of tungstate, suggesting that the V-nitrogenase was able to incorporate tungstate. Tungstate was able to substitute for molybdate in repressing transcription of a Mo-transport gene, but it did not repress transcription of the vnfH gene, which was repressed by Mo. The availability of Mo and V plays an important role in controlling whether the Mo-or the V-nitrogenase is used for nitrogen fixation.
Extended parental care in crustaceans: an update
THIEL,MARTIN;
Revista chilena de historia natural , 2003, DOI: 10.4067/S0716-078X2003000200007
Abstract: many crustacean species show extended parental care (xpc) for fully developed juvenile offspring. herein, the present state of knowledge of the major patterns and consequences of xpc is reviewed, and furthermore important future research topics are identified. crustaceans with xpc are found in marine, freshwater and terrestrial environments, but care for late juvenile stages appears to be more common in terrestrial environments. in all species, females participate or even take the main share of xpc activities. crustaceans that carry their offspring during xpc commonly release early juvenile stages, while species inhabiting particular microhabitats may host offspring until these have reached subadult or adult stages. apart from providing a suitable and safe microhabitat to small offspring, parents share food with, groom or actively defend their juveniles. some of the most important benefits of xpc include improved juvenile growth and survival. xpc may also lead to conflicts among developing offspring or between parents and offspring, especially during later phases of xpc when resources (food and space) become increasingly limiting. similarly, during long-lasting cohabitation, epibionts (e.g., parasites) may be transferred from parents to offspring, as is indicated by observational evidence. for several species, local recruitment, where juveniles recruit in the immediate vicinity of their parents, has been observed. under these conditions, local populations may rapidly increase, potentially leading to intra-specific competition for space, thereby possibly causing a decrease in reproductive activity or a reduction in length of xpc. another consequence of xpc and local recruitment could be limited dispersal potential, but some marine crustaceans with xpc and local recruitment nevertheless have a wide geographic distribution. it is hypothesized that the existence of suitable dispersal vectors such as floating macroalgae or wood can lead to a substantial increase in dispe
Extended parental care in crustaceans: an update Cuidado parental extendido en crustáceos: conocimiento actual
MARTIN THIEL
Revista chilena de historia natural , 2003,
Abstract: Many crustacean species show extended parental care (XPC) for fully developed juvenile offspring. Herein, the present state of knowledge of the major patterns and consequences of XPC is reviewed, and furthermore important future research topics are identified. Crustaceans with XPC are found in marine, freshwater and terrestrial environments, but care for late juvenile stages appears to be more common in terrestrial environments. In all species, females participate or even take the main share of XPC activities. Crustaceans that carry their offspring during XPC commonly release early juvenile stages, while species inhabiting particular microhabitats may host offspring until these have reached subadult or adult stages. Apart from providing a suitable and safe microhabitat to small offspring, parents share food with, groom or actively defend their juveniles. Some of the most important benefits of XPC include improved juvenile growth and survival. XPC may also lead to conflicts among developing offspring or between parents and offspring, especially during later phases of XPC when resources (food and space) become increasingly limiting. Similarly, during long-lasting cohabitation, epibionts (e.g., parasites) may be transferred from parents to offspring, as is indicated by observational evidence. For several species, local recruitment, where juveniles recruit in the immediate vicinity of their parents, has been observed. Under these conditions, local populations may rapidly increase, potentially leading to intra-specific competition for space, thereby possibly causing a decrease in reproductive activity or a reduction in length of XPC. Another consequence of XPC and local recruitment could be limited dispersal potential, but some marine crustaceans with XPC and local recruitment nevertheless have a wide geographic distribution. It is hypothesized that the existence of suitable dispersal vectors such as floating macroalgae or wood can lead to a substantial increase in dispersal distances of crustaceans with XPC via rafting, surpassing that of crustaceans with pelagic larvae. Since crustaceans with XPC may be particularly susceptible to changing environmental conditions, especially in the terrestrial environment where populations are often small and locally restricted, conservation of biodiversity should focus on these (and other invertebrate) species with XPC Muchas especies de crustáceos presentan cuidado parental extendido (XPC), donde individuos juveniles completamente desarrollados son cuidados por los padres. En la presente contribución se revisa el conocim
Europeanisation and the rescaling of water services: Agency and state spatial strategies in the Algarve, Portugal
Andreas Thiel
Water Alternatives , 2009,
Abstract: Institutional arrangements to provide water services have been reshaped extensively worldwide. This paper provides a theory-informed account of the way in which water service provision has been physically and institutionally restructured in the Algarve, Portugal over the years. Ever-expanding demands for water services by the tourism sector, along with European Union (EU) regulations and money, made the local people dependent on national policy for water service provision. Parts of the Portuguese national elite, favouring the construction of water resources as "strategic", "social" goods rather than "economic", "scarce" goods, worked towards installing national level control over water services. They became part of the state’s decentralised hegemonic spatial strategy for expansion of tourism in the Algarve. The district level was constituted as a decentralised level of national resource governance. The case study shows the role of European policies in restructuring the spatio-temporal order in the Algarve and strengthening the influence of the national state within the region. The reconfiguration of the water sector in Portugal illustrates 'Spatial Keynesianism' with half-hearted mercantilisación of water services as an outcome of a juxtaposition of a nationally rooted state-led water service provision within more flexible approaches originating at the European level. A consequential outcome has been that water quality, sewage treatment and reliability of services, has significantly improved in line with European requirements.
Development of endosperm transfer cells in barley
Johannes Thiel
Frontiers in Plant Science , 2014, DOI: 10.3389/fpls.2014.00108
Abstract: Endosperm transfer cells (ETCs) are positioned at the intersection of maternal and filial tissues in seeds of cereals and represent a bottleneck for apoplasmic transport of assimilates into the endosperm. Endosperm cellularization starts at the maternal-filial boundary and generates the highly specialized ETCs. During differentiation barley ETCs develop characteristic flange-like wall ingrowths to facilitate effective nutrient transfer. A comprehensive morphological analysis depicted distinct developmental time points in establishment of transfer cell (TC) morphology and revealed intracellular changes possibly associated with cell wall metabolism. Embedded inside the grain, ETCs are barely accessible by manual preparation. To get tissue-specific information about ETC specification and differentiation, laser microdissection (LM)-based methods were used for transcript and metabolite profiling. Transcriptome analysis of ETCs at different developmental stages by microarrays indicated activated gene expression programs related to control of cell proliferation and cell shape, cell wall and carbohydrate metabolism reflecting the morphological changes during early ETC development. Transporter genes reveal distinct expression patterns suggesting a switch from active to passive modes of nutrient uptake with the onset of grain filling. Tissue-specific RNA-seq of the differentiating ETC region from the syncytial stage until functionality in nutrient transfer identified a high number of novel transcripts putatively involved in ETC differentiation. An essential role for two-component signaling (TCS) pathways in ETC development of barley emerged from this analysis. Correlative data provide evidence for abscisic acid and ethylene influences on ETC differentiation and hint at a crosstalk between hormone signal transduction and TCS phosphorelays. Collectively, the data expose a comprehensive view on ETC development, associated pathways and identified candidate genes for ETC specification.
The generator rank for C*-algebras
Hannes Thiel
Mathematics , 2012,
Abstract: The invariant that assigns to a C*-algebra its minimal number of generators lacks natural permanence properties. In particular, it may increase when passing to ideals or inductive limits. It is therefore hard to compute this invariant directly. To obtain a better behaved theory, we not only ask if k generators exist, but also if such tuples are dense. This defines the generator rank, which we show has many of the permanence properties that are also satisfied by other noncommutative dimension theories. In particular, it does not increase when passing to ideals, quotients or inductive limits. The definition of the generator rank is analogous to that of the real rank, and we show that the latter always dominates the generator rank. The most interesting value of the generator rank is one, which means exactly that the generators form a generic set, that is, a dense G_delta-subset. We compute the generator rank of homgeneous C*-algebras, which allows us to deduce that certain AH-algebras have generator rank one. For example, every AF-algebra has generator rank one and therefore contains a dense set of generators.
The topological dimension of type I C*-algebras
Hannes Thiel
Mathematics , 2012, DOI: 10.1007/978-3-642-39459-1_16
Abstract: While there is only one natural dimension concept for separable, metric spaces, the theory of dimension in noncommutative topology ramifies into different important concepts. To accommodate this, we introduce the abstract notion of a noncommutative dimension theory by proposing a natural set of axioms. These axioms are inspired by properties of commutative dimension theory, and they are for instance satisfied by the real and stable rank, the decomposition rank and the nuclear dimension. We add another theory to this list by showing that the topological dimension, as introduced by Brown and Pedersen, is a noncommutative dimension theory of type I C*-algebras. We also give estimates of the real and stable rank of a type I C*-algebra in terms of its topological dimension.
A counter-example to Martino's conjecture about generic Calogero-Moser families
Ulrich Thiel
Mathematics , 2013, DOI: 10.1007/s10468-013-9449-4
Abstract: The Calogero-Moser families are partitions of the irreducible characters of a complex reflection group derived from the block structure of the corresponding restricted rational Cherednik algebra. It was conjectured by Martino in 2009 that the generic Calogero-Moser families coincide with the generic Rouquier families, which are derived from the corresponding Hecke algebra. This conjecture is already proven for the whole infinite series G(m,p,n) and for the exceptional group G4. A combination of theoretical facts with explicit computations enables us to determine the generic Calogero-Moser families for the nine exceptional groups G4, G5, G6, G8, G10, G23=H3, G24, G25, and G26. We show that the conjecture holds for all these groups - except surprisingly for the group G25, thus being the first and only-known counter-example so far.
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