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Search Results: 1 - 10 of 1652 matches for " Martina Hausner "
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Design and evaluation of 16S rRNA sequence based oligonucleotide probes for the detection and quantification of Comamonas testosteroni in mixed microbial communities
Stephan Bathe, Martina Hausner
BMC Microbiology , 2006, DOI: 10.1186/1471-2180-6-54
Abstract: We have designed an oligonucleotide probe for use in fluorescent in situ hybridization (FISH) and two pairs of PCR primers targeting a C. testosteroni subgroup. The FISH probe and one of the PCR primer pairs are suitable for quantification of C. testosteroni in mixed microbial communities using FISH followed by quantitative image analysis or real-time quantitative PCR, respectively. This has been shown by analysis of samples from an enrichment of activated sludge on testosterone resulting in an increase in abundance and finally isolation of C. testosteroni. Additionally, we have successfully used quantitative PCR to follow the C. testosteroni abundance during a laboratory scale wastewater bioaugmentation experiment.The oligonucleotides presented here provide a useful tool to study C. testosteroni population dynamics in mixed microbial communities.Comamonas testosteroni is a ubiquitously occuring β-proteobacterial species which has been isolated from aquatic as well as terrestrial environments. It has been shown to be capable of transformations of steroid compounds [1-4] and also of degradation of aromatic hydrocarbons [5-10]. C. testosteroni is thus of interest for potential biotechnological applications such as chemical transformations in fine chemical manufacturing [11] and bioremediation processes [7,12], as indicated by laboratory results.Due to the widespread environmental distribution and the potential relevance of C. testosteroni in biotransformation processes, it may be of interest to follow the population dynamics of this species over time in a mixed-species environment. Since culture-dependent methods are not sufficiently accurate to detect and quantify one particular species within a mixed bacterial community, methods targeting the 16S rRNA and/or its gene(s) need to be applied to such a problem, as has already been done in previous investigations [13-16]. Probes for species of the genera Comamonas and Delftia (COM1424 [17], and PPT [18]) as well as for s
Karsten Rodenacker,Andreas Brühl,Martina Hausner,Martin Kühn
Image Analysis and Stereology , 2000, DOI: 10.5566/ias.v19.p151-156
Abstract: Populations of bacteria in sludge flocs and biofilm marked by fluorescence marked with fluorescent probes are digitised with a confocal laser scanning microscope. These data are used to analyse the microbial community structure, to obtain information on the localisation of specific bacterial groups and to examine gene expression. This information is urgently required for an in-depth understanding of the function and, more generally, the microbial ecology of biofilms. Methods derived from quantitative image analysis are applied to digitised data from confocal laser scanning microscopes to obtain quantitative descriptions of volumetric, topological (and topographical) properties of different compartments of the components under research. In addition to free-moving flocs, also biofilms attached to a substratum in an experimental environment are analysed. Growth form as well as interaction of components are quantitatively described. Classical measurements of volume and intensity (shape, distribution) and distance dependent interaction measurements using methods from mathematical morphology are performed. Mainly image (volume) processing methods are outlined. Segmented volumes are globally and individually (in terms of 3Dconnected components) measured and used for distance mapping transform as well as for estimation of geodesic distances from the substrate. All transformations are applied on the 3D data set. Resulting distance distributions are quantified and related to information on the identity and activity of the probe-identified bacteria.
Simple approach for high-contrast optical imaging and characterization of graphene-based sheets
Inhwa Jung,Matthew Pelton,Richard Piner,Dmitriy A. Dikin,Sasha Stankovich,Supinda Watcharotone,Martina Hausner,Rodney S. Ruoff
Physics , 2007, DOI: 10.1021/nl0714177
Abstract: A simple optical method is presented for identifying and measuring the effective optical properties of nanometer-thick, graphene-based materials, based on the use of substrates consisting of a thin dielectric layer on silicon. High contrast between the graphene-based materials and the substrate is obtained by choosing appropriate optical properties and thickness of the dielectric layer. The effective refractive index and optical absorption coefficient of graphene oxide, thermally reduced graphene oxide, and graphene are obtained by comparing the predicted and measured contrasts.
HrcQ Provides a Docking Site for Early and Late Type III Secretion Substrates from Xanthomonas
Christian Lorenz, Jens Hausner, Daniela Büttner
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0051063
Abstract: Pathogenicity of many Gram-negative bacteria depends on a type III secretion (T3S) system which translocates bacterial effector proteins into eukaryotic cells. The membrane-spanning secretion apparatus is associated with a cytoplasmic ATPase complex and a predicted cytoplasmic (C) ring structure which is proposed to provide a substrate docking platform for secreted proteins. In this study, we show that the putative C ring component HrcQ from the plant pathogenic bacterium Xanthomonas campestris pv. vesicatoria is essential for bacterial pathogenicity and T3S. Fractionation studies revealed that HrcQ localizes to the cytoplasm and associates with the bacterial membranes under T3S-permissive conditions. HrcQ binds to the cytoplasmic T3S-ATPase HrcN, its predicted regulator HrcL and the cytoplasmic domains of the inner membrane proteins HrcV and HrcU. Furthermore, we observed an interaction between HrcQ and secreted proteins including early and late T3S substrates. HrcQ might therefore act as a general substrate acceptor site of the T3S system and is presumably part of a larger protein complex. Interestingly, the N-terminal export signal of the T3S substrate AvrBs3 is dispensable for the interaction with HrcQ, suggesting that binding of AvrBs3 to HrcQ occurs after its initial targeting to the T3S system.
What Do the IUCN Categories Really Protect? A Case Study of the Alpine Regions in Spain
Lorena Mu?oz,Vera Helene Hausner
Sustainability , 2013, DOI: 10.3390/su5062367
Abstract: Protected area (PA) coverage is used as an indicator of biodiversity protection worldwide. The effectiveness of using PAs as indicators has been questioned due to the diversity of categories encompassed by such designations, especially in PAs established for purposes other than biodiversity protection. Although international standards have been developed by the International Union for Conservation of Nature (IUCN), the policies on the ground have been developed independently of the IUCN categories, thus making the IUCN categories dubious measures of biodiversity conservation. Management plans are crucial for the effective management of parks and for guidance on how biodiversity maintenance should be prioritized relative to other goals. We therefore analyzed the aims and regulations of the management plans of alpine PAs in Spain as a first step in evaluating conservation performance. We used content analysis and correspondence analysis of instrumental variables (CAiv) to assess how aims and regulations vary in relation to three explanatory factors: IUCN categories, vegetation zones and autonomous communities. We found that the aims of many parks were vague, without clear indications of how to prioritize biodiversity goals. Furthermore, only 50% of the parks studied had any management plan, which strengthens our argument concerning the lack of clear guidance in PA management. Although certain aims were correlated with the IUCN categories, the regulations showed no clear relationship to international policies, which indicates that these aims do not necessarily influence management practices. Devolution to autonomous communities could be one explanation for the large variation in management practices among parks. Further studies are needed to evaluate the impact of such management policies on biodiversity.
Alternative UV Sensors Based on Color-Changeable Pigments  [PDF]
Martina Vikova, Michal Vik
Advances in Chemical Engineering and Science (ACES) , 2011, DOI: 10.4236/aces.2011.14032
Abstract: Photochromism is a chemical process in which a compound undergoes a reversible change between two states having separate absorption spectra, i.e. different color [1]. In our previous work we have published some solutions of problems of measuring photochromic textile sample by standard commercial spectrophotometric systems [2]. Main problem with measurement of kinetic behavior of photochromic pigments by standard spectrophotometer is relatively long time period between individual measurements (5 s) and impossibility of measuring whole color change during exposure without interruption of illumination of sample during measurement. It means, standard commercial spectrophotometers enable off-line measurement of kinetic behavior during exposure period and quasi on-line measurement during reversion period. Based on this problem, it is only possible to obtain precise data during reversion—decay process and growth process (exposure) is affected by high variability of data. Following this knowledge, we developed original experimenttal system with short time scanning of color change of photochromic samples during growth and decay period of color change. In this study it is presented new view on the relationship between intensity of UV-A radiation and color change half-life t1/2. Via this relation, it is demonstrated the possibility of the flexible textile-based sensors construction in the area of the radiation intensity identification.
Identifying nurse staffing research in Medline: development and testing of empirically derived search strategies with the PubMed interface
Michael Simon, Elke Hausner, Susan F Klaus, Nancy E Dunton
BMC Medical Research Methodology , 2010, DOI: 10.1186/1471-2288-10-76
Abstract: A set of relevant references in PubMed/Medline was identified by means of three systematic reviews. This development set was used to detect candidate free-text and MeSH terms. The frequency of these terms was compared to a random sample from PubMed/Medline in order to identify terms specific to nurse staffing research, which were then used to develop a sensitive, precise and balanced search strategy. To determine their precision, the newly developed search strategies were tested against a) the pool of relevant references extracted from the systematic reviews, b) a reference set identified from an electronic journal screening, and c) a sample from PubMed/Medline. Finally, all newly developed strategies were compared to PubMed's Health Services Research Queries (PubMed's HSR Queries).The sensitivities of the newly developed search strategies were almost 100% in all of the three test sets applied; precision ranged from 6.1% to 32.0%. PubMed's HSR queries were less sensitive (83.3% to 88.2%) than the new search strategies. Only minor differences in precision were found (5.0% to 32.0%).As with other literature on health services research, nurse staffing studies are difficult to identify in PubMed/Medline. Depending on the purpose of the search, researchers can choose between high sensitivity and retrieval of a large number of references or high precision, i.e. and an increased risk of missing relevant references, respectively. More standardized terminology (e.g. by consistent use of the term "nurse staffing") could improve the precision of future searches in this field. Empirically selected search terms can help to develop effective search strategies. The high consistency between all test sets confirmed the validity of our approach.PubMed/Medline contains more than 18 million references. The identification of relevant literature in this wide-ranging source is of great importance to researchers in remaining up-to-date with the latest developments in the field of interest,
Routine development of objectively derived search strategies
Elke Hausner, Siw Waffenschmidt, Thomas Kaiser, Michael Simon
Systematic Reviews , 2012, DOI: 10.1186/2046-4053-1-19
Abstract: Our aim in this paper is to describe the empirically guided development process for search strategies as applied by the German Institute for Quality and Efficiency in Health Care (Institut für Qualit?t und Wirtschaftlichkeit im Gesundheitswesen, or "IQWiG"). This strategy consists of the following steps: generation of a test set, as well as the development, validation and standardized documentation of the search strategy.We illustrate our approach by means of an example, that is, a search for literature on brachytherapy in patients with prostate cancer. For this purpose, a test set was generated, including a total of 38 references from 3 systematic reviews. The development set for the generation of the strategy included 25 references. After application of textual analytic procedures, a strategy was developed that included all references in the development set. To test the search strategy on an independent set of references, the remaining 13 references in the test set (the validation set) were used. The validation set was also completely identified.Our conclusion is that an objectively derived approach similar to that used in search filter development is a feasible way to develop and validate reliable search strategies. Besides creating high-quality strategies, the widespread application of this approach will result in a substantial increase in the transparency of the development process of search strategies.Over the past few years, information retrieval has become more and more professionalized [1], and information specialists are considered full members of a research team conducting systematic reviews. Trial search coordinators in Cochrane Collaboration review groups are a good example of this development. They manage the search process in its entirety, from designing the search strategy to conducting and documenting the actual search and managing the references [2]. Information specialists also develop search filters that enable the efficient searching of bibliogr
The Ghost of Development Past: the Impact of Economic Security Policies on Saami Pastoral Ecosystems
Vera H. Hausner,Per Fauchald,Torkild Tveraa,Elisabeth Pedersen
Ecology and Society , 2011, DOI: 10.5751/es-04193-160304
Abstract: To ensure economic viability over time, any efforts to meet the Millennium Development Goals need to reconcile conservation with development interventions. Particularly, in marginal and risk prone areas erosion of resilience could make production systems more susceptible to environmental risks that compromise the economic security. By longitudinal analyses of long-term data records we investigated the impacts of big push policies on Saami pastoral ecosystems in Arctic Norway. The big push was accompanied by reindeer herd accumulation and a corresponding degradation of resilience, increasing the susceptibility to herd losses to predators and adverse winters. For the last 20 years the Norwegian government has worked to halt degradation of pasture ecosystems and reduce susceptibility to environmental risks. These intended win-win policies have mainly been based on economic incentives, which have been developed together with Saami pastoralists through negotiated agreements. We argue that the continued degradation of the Saami pastoral ecosystems is a "ghost of the development past", as the big push policies have resulted in an economic security trap (EST). The gradual reduction of resilience has persisted as the ex post payments of disaster relief and predator compensation have impeded the long-term actions to reduce susceptibility to environmental risks, i.e., ex ante policies, thereby increasing dependency on elevated economic inputs to manage the risks. The transfer of liability for managing risks to the benefactor, both through ex ante and ex post policies, has further discouraged and constrained opportunities for adaptation by the pastoralists.
Energy-Efficient Hardware Architectures for the Packet Data Convergence Protocol in LTE-Advanced Mobile Terminals
Shadi Traboulsi,Valerio Frascolla,Nils Pohl,Josef Hausner
VLSI Design , 2013, DOI: 10.1155/2013/369627
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