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• 1
Article
Language: German
In: BIOspektrum, 2017, Vol.23(5), pp.525-528
Description: Single-cell RNA-seq has revolutionized our understanding of cellular heterogeneity in a wide spectrum of biological processes. Pioneering studies suggest complex mechanisms and division of labour employed by the bacterial pathogen Salmonella to subvert host cell functions during infection. Here we describe some of our findings from single-cell RNA-seq studies that have revealed and characterized heterogeneity between individual cells infected with this intracellular pathogen, and outline future challenges in this burgeoning field.
Keywords: Life Sciences ; Life Sciences, General ; Biochemistry, General ; Human Genetics ; Microbiology ; Pharmacology/Toxicology ; Sciences (General);
ISSN: 0947-0867
E-ISSN: 1868-6249
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• 2
Article
Language: English
In: Analytical and Bioanalytical Chemistry, 2009, Vol.395(3), pp.719-727
Description: To establish planar biomimetic membranes across large scale partition aperture arrays, we created a disposable single-use horizontal chamber design that supports combined optical–electrical measurements. Functional lipid bilayers could easily and efficiently be established across CO 2 laser micro-structured 8 × 8 aperture partition arrays with average aperture diameters of 301 ± 5 μm. We addressed the electro-physical properties of the lipid bilayers established across the micro-structured scaffold arrays by controllable reconstitution of biotechnological and physiological relevant membrane peptides and proteins. Next, we tested the scalability of the biomimetic membrane design by establishing lipid bilayers in rectangular 24 × 24 and hexagonal 24 × 27 aperture arrays, respectively. The results presented show that the design is suitable for further developments of sensitive biosensor assays, and furthermore demonstrate that the design can conveniently be scaled up to support planar lipid bilayers in large square-centimeter partition arrays. Figure Fluorescent image of a large 24 × 24 rectangular bilayer array
Keywords: Black lipid membrane ; Array ; Optical–electrical measurements ; Membrane-spanning peptides ; Membrane protein
ISSN: 1618-2642
E-ISSN: 1618-2650
Source: Springer Science & Business Media B.V.
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• 3
Article
Language: English
In: Plant and Soil, 2010, Vol.332(1), pp.163-176
Description: Water flow from soil to plants depends on the properties of the soil next to roots, the rhizosphere. Although several studies showed that the rhizosphere has different properties than the bulk soil, effects of the rhizosphere on root water uptake are commonly neglected. To investigate the rhizosphere’s properties we used neutron radiography to image water content distributions in soil samples planted with lupins during drying and subsequent rewetting. During drying, the water content in the rhizosphere was 0.05 larger than in the bulk soil. Immediately after rewetting, the picture reversed and the rhizosphere remained markedly dry. During the following days the water content of the rhizosphere increased and after 60 h it exceeded that of the bulk soil. The rhizosphere’s thickness was approximately 1.5 mm. Based on the observed dynamics, we derived the distinct, hysteretic and time-dependent water retention curve of the rhizosphere. Our hypothesis is that the rhizosphere’s water retention curve was determined by mucilage exuded by roots. The rhizosphere properties reduce water depletion around roots and weaken the drop of water potential towards roots, therefore favoring water uptake under dry conditions, as demonstrated by means of analytical calculation of water flow to a single root.
Keywords: Root water uptake ; Water retention curve ; Rhizosphere ; Neutron radiography ; Mucilage ; Hysteresis
ISSN: 0032-079X
E-ISSN: 1573-5036
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• 4
Article
Language: English
In: Transport in Porous Media, 2016, Vol.112(1), pp.207-227
Description: According to experimental observations, capillary trapping is strongly dependent on the roughness of the pore–solid interface. We performed imbibition experiments in the range of capillary numbers ( Ca ) from $$10^{-6}$$ 10 - 6 to $$5\times 10^{-5}$$ 5 × 10 - 5 using 2D-micromodels, which exhibit a rough surface. The microstructure comprises a double-porosity structure with pronounced macropores. The dynamics of precursor thin-film flow and its importance for capillary trapping are studied. The experimental data for thin-film flow advancement show a square-root time dependence. Based on the experimental data, we conducted inverse modeling to investigate the influence of surface roughness on the dynamic contact angle of precursor thin-film flow. Our experimental results show that trapped gas saturation decreases logarithmically with an increasing capillary number. Cluster analysis shows that the morphology and number of trapped clusters change with capillary number. We demonstrate that capillary trapping shows significant differences for vertical flow and horizontal flow. We found that our experimental results agree with theoretical results of percolation theory for $$Ca =10^{-6}$$ C a = 10 - 6 : (i) a universal power-like cluster size distribution, (ii) the linear surface–volume relationship of trapped clusters, and (iii) the existence of the cutoff correlation length for the maximal cluster height. The good agreement is a strong argument that the experimental cluster size distribution is caused by a percolation-like trapping process (ordinary percolation). For the first time, it is demonstrated experimentally that the transition zone model proposed by Wilkinson (Phys Rev A 30:520–531, 1984) can be applied to 2D-micromodels, if bicontinuity is generalized such that it holds for the thin-film water phase and the bulk gas phase.
Keywords: 2D-micromodel with rough surface ; Precursor thin-film flow ; Snap-off trapping ; Universal power law ; Ordinary bond percolation
ISSN: 0169-3913
E-ISSN: 1573-1634
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• 5
Article
Language: English
In: Theory of Computing Systems, 2003, Vol.36(4), pp.375-386
Description: In 1977 Young proposed a voting scheme that extends the Condorcet Principle based on the fewest possible number of voters whose removal yields a Condorcet winner. We prove that both the winner and the ranking problem for Young elections is complete for \p || NP , the class of problems solvable in polynomial time by parallel access to NP. Analogous results for Lewis Carroll's 1876 voting scheme were recently established by Hemaspaandra et al. In contrast, we prove that the winner and ranking problems in Fishburn's homogeneous variant of Carroll's voting scheme can be solved efficiently by linear programming.
Keywords: Computation ; Elections ; Complexity ; Polynomials ; Linear Programming ; Ranking ; Voters ; Voting ; Computing Milieux (General) (Ci);
ISSN: 1432-4350
E-ISSN: 1433-0490
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• 6
Article
Language: English
In: Journal of neurology, March 2006, Vol.253(3), pp.349-56
Description: Motor dysfunction is an important clinical finding in patients with liver cirrhosis and mild forms of hepatic encephalopathy. The mechanisms and clinical appearance of motor impairment in patients with liver cirrhosis are not completely understood. We studied fine motor control in forty four patients with advanced liver cirrhosis (excluding those with hepatic encephalopathy grade II) and 48 healthy controls using a kinematic analysis of standardized handwriting tests. We analysed parameters of velocity, the ability to coordinate and the level of automatisation of handwriting movements. Furthermore, we studied the association between impairment of handwriting and clinical neuro-psychiatric symptoms. As compared with control subjects, patients showed a statistically significant reduction of movement peak velocity in all handwriting tasks as well as a substantial increase of number of velocity inversions per stroke. Using a z-score based assessment we found impairment of handwriting in fourteen out of forty four patients (31.8 %). The deterioration of handwriting was associated with clinical symptoms of motor dysfunction, such as bradykinesia, adiadochokinesia, dysmetria of upper extremities and gait ataxia. This is the first study that quantitatively investigates impairment of handwriting in patients with liver cirrhosis. Our findings suggest the application of kinematic analysis of handwriting for diagnostics of motor dysfunction in patients with mild forms of hepatic encephalopathy.
Keywords: Handwriting ; Liver Cirrhosis -- Complications ; Movement Disorders -- Etiology ; Psychomotor Performance -- Physiology
ISSN: 0340-5354
E-ISSN: 14321459
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• 7
Article
Language: English
In: Environmental Earth Sciences, 2013, Vol.69(2), pp.317-333
Description: Sustainable water quality management requires a profound understanding of water fluxes (precipitation, run-off, recharge, etc.) and solute turnover such as retention, reaction, transformation, etc. at the catchment or landscape scale. The Water and Earth System Science competence cluster (WESS, http://www.wess.info/ ) aims at a holistic analysis of the water cycle coupled to reactive solute transport, including soil–plant–atmosphere and groundwater–surface water interactions. To facilitate exploring the impact of land-use and climate changes on water cycling and water quality, special emphasis is placed on feedbacks between the atmosphere, the land surface, and the subsurface. A major challenge lies in bridging the scales in monitoring and modeling of surface/subsurface versus atmospheric processes. The field work follows the approach of contrasting catchments, i.e. neighboring watersheds with different land use or similar watersheds with different climate. This paper introduces the featured catchments and explains methodologies of WESS by selected examples.
Keywords: Water and solute fluxes ; Water quality ; Catchments ; Land-surface atmosphere exchange ; Processes and feedbacks ; Modeling ; Monitoring
ISSN: 1866-6280
E-ISSN: 1866-6299
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• 8
Article
Language: English
In: Environmental Earth Sciences, 2017, Vol.76(1), pp.1-25
Description: This article provides an overview about the Bode River catchment that was selected as the hydrological observatory and main region for hydro-ecological research within the TERrestrial ENvironmental Observatories Harz/Central German Lowland Observatory. It first provides information about the general characteristics of the catchment including climate, geology, soils, land use, water quality and aquatic ecology, followed by the description of the interdisciplinary research framework and the monitoring concept with the main components of the multi-scale and multi-temporal monitoring infrastructure. It also shows examples of interdisciplinary research projects aiming to advance the understanding of complex hydrological processes under natural and anthropogenic forcings and their interactions in a catchment context. The overview is complemented with research work conducted at a number of intensive research sites, each focusing on a particular functional zone or specific components and processes of the hydro-ecological system.
Keywords: Monitoring ; Catchment ; Water quality ; Observatory ; Water fluxes
ISSN: 1866-6280
E-ISSN: 1866-6299
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• 9
Article
Language: English
In: Wireless Personal Communications, 1999, Vol.11(1), pp.45-62
Description: One of the most widely used buzzwords in mobile communications of the recent years is Space Division Multiple Access (SDMA). The introduction of an additional space domain multiple access component is likely to boost system capacity, due to the spatial reuse of physical channels within one cell. While early approaches of SDMA system modelling show capacity to be gained in the order of 300 to 400%, there remains some more in depth system analysis to be done, as inhomogeneities in the user distribution are expected to likely cause dramatic drops in the additional capacity gained by SDMA. The spatial distribution of terminals directly influences the number of channels to be gained by spatial multiplexing. Therefore, it is not until detailed models for user distribution, user mobility and the traffic load generated by users are combined with a model of the SDMA radio subsystem, that realistic approximations for these capacity gains are possible. In this paper, we discuss the issues in modelling and simulation of SDMA systems. We present an approach for integrated SDMA system modelling, discuss analytic teletraffic dimensioning methods for macro- and microcellular environments and their relevance to SDMA systems, and present some early simulation results.
Keywords: SDMA ; smart antenna systems ; capacity ; traffic models ; mobility models ; simulation
ISSN: 0929-6212
E-ISSN: 1572-834X
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• 10
Article
Language: English
In: European Journal of Applied Physiology, 2018, Vol.118(1), pp.195-203
Description: Purpose Testing of investigational drugs in animal models is a critical step in drug development. Current models of pulmonary hypertension (PH) have limitations. The most relevant outcome parameters such as pulmonary artery pressure (PAP) are measured invasively which requires anesthesia of the animal. We developed a new canine PH model in which pulmonary vasodilators can be characterized in conscious dogs and lung selectivity can be assessed non-invasively. Methods Telemetry devices were implanted to measure relevant hemodynamic parameters in conscious dogs. A hypoxic chamber was constructed in which the animals were placed in a conscious state. By reducing the inspired oxygen fraction (FiO2) to 10%, a hypoxic pulmonary vasoconstriction was induced leading to PH. The PDE-5 inhibitor sildenafil, the current standard of care was compared to atrial natriuretic peptide (ANP). Results The new hypoxic chamber provided a stable hypoxic atmosphere during all experiments. The mean PAP under normoxic conditions was 15.8 ± 1.8 mmHg. Hypoxia caused a reliable increase in mean PAP (+ 12.2 ± 3.2 mmHg, p 〈 0.0001). Both, sildenafil (− 6.8 ± 4.4 mmHg) and ANP (− 6.4 ± 3.8 mmHg) significantly (p 〈 0.05) decreased PAP. Furthermore sildenafil and ANP showed similar effects on systemic hemodynamics. In subsequent studies, the in vitro effects and gene expression pattern of the two pathways were exemplified. Conclusions By combining the hypoxic environment with the telemetric approach, we could successfully establish a new acute PH model. Sildenafil and ANP demonstrated equal effects regarding pulmonary selectivity. This non-invasive model could help to rapidly screen pulmonary vasodilators with decreased animal burden.
Keywords: Pulmonary hypertension ; Atrial natriuretic peptide ; Drug development ; Sildenafil ; Dog ; Animal model
ISSN: 1439-6319
E-ISSN: 1439-6327
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