Spinorial Characterizations of Surfaces into 3-dimensional pseudo-Riemannian Space Forms

We give a spinorial characterization of isometrically immersed surfaces of arbitrary signature into 3-dimensional pseudo-Riemannian space forms. For Lorentzian surfaces, this generalizes a recent work of the first author in $\mathbb{R}^{2,1}$ to other Lorentzian space forms. We also characterize immersions of Riemannian surfaces in these spaces. From this we can deduce analogous results for timelike immersions of Lorentzian surfaces in space forms of corresponding signature, as well as for spacelike and timelike immersions of surfaces of signature (0,2), hence achieving a complete spinorial description for this class of pseudo-Riemannian immersions.Comment: 9 page

Active phase and amplitude fluctuations of flagellar beating

The eukaryotic flagellum beats periodically, driven by the oscillatory dynamics of molecular motors, to propel cells and pump fluids. Small, but perceivable fluctuations in the beat of individual flagella have physiological implications for synchronization in collections of flagella as well as for hydrodynamic interactions between flagellated swimmers. Here, we characterize phase and amplitude fluctuations of flagellar bending waves using shape mode analysis and limit cycle reconstruction. We report a quality factor of flagellar oscillations, $Q=38.0\pm 16.7$ (mean$\pm$s.e.). Our analysis shows that flagellar fluctuations are dominantly of active origin. Using a minimal model of collective motor oscillations, we demonstrate how the stochastic dynamics of individual motors can give rise to active small-number fluctuations in motor-cytoskeleton systems.Comment: accepted for publication in Physical Review Letter

Comparison of long and short axis quantification of left ventricular volume parameters by cardiovascular magnetic resonance, with ex-vivo validation

<p>Abstract</p> <p>Background</p> <p>The purpose of the study was to compare the accuracy and evaluation time of quantifying left ventricular (LV), left atrial (LA) volume and LV mass using short axis (SAX) and long axis (LAX) methods when using cardiovascular magnetic resonance (CMR).</p> <p>Materials and methods</p> <p>We studied 12 explanted canine hearts and 46 patients referred for CMR (29 male, age 47 ± 18 years) in a clinical 1.5 T CMR system, using standard cine sequences. In standard short axis stacks of various slice thickness values in dogs and 8 mm slice thickness (gap 2 mm) in patients, we measured LV volumes using reference slices in a perpendicular, long axis orientation using certified software. Volumes and mass were also measured in six radial long axis (LAX) views.</p> <p>LV parameters were also assessed for intra- and inter-observer variability. In 24 patients, we also analyzed reproducibility and evaluation time of two very experienced (> 10 years of CMR reading) readers for SAX and LAX.</p> <p>Results</p> <p>In the explanted dog hearts, there was excellent agreement between ex vivo data and LV mass and volume data as measured by all methods for both, LAX (r²= 0.98) and SAX (r²= 0.88 to 0.98). LA volumes, however, were underestimated by 13% using the LAX views. In patients, there was a good correlation between all three assessed methods (r²≥ 0.95 for all). In experienced clinical readers, left-ventricular volumes and ejection fraction as measured in LAX views showed a better inter-observer reproducibility and a 27% shorter evaluation time.</p> <p>Conclusion</p> <p>When compared to an ex vivo standard, both, short axis and long axis techniques are highly accurate for the quantification of left ventricular volumes and mass. In clinical settings, however, the long axis approach may be more reproducible and more time-efficient. Therefore, the rotational long axis approach is a viable alternative for the clinical assessment of cardiac volumes, function and mass.</p

Allopolyploid speciation and ongoing backcrossing between diploid progenitor and tetraploid progeny lineages in the Achillea millefolium species complex: analyses of single-copy nuclear genes and genomic AFLP

<p>Abstract</p> <p>Background</p> <p>In the flowering plants, many polyploid species complexes display evolutionary radiation. This could be facilitated by gene flow between otherwise separate evolutionary lineages in contact zones. <it>Achillea collina </it>is a widespread tetraploid species within the <it>Achillea millefolium </it>polyploid complex (Asteraceae-Anthemideae). It is morphologically intermediate between the relic diploids, <it>A. setacea</it>-2x in xeric and <it>A. asplenifolia</it>-2x in humid habitats, and often grows in close contact with either of them. By analyzing DNA sequences of two single-copy nuclear genes and the genomic AFLP data, we assess the allopolyploid origin of <it>A. collina</it>-4x from ancestors corresponding to <it>A. setacea</it>-2x and <it>A. asplenifolia</it>-2x, and the ongoing backcross introgression between these diploid progenitor and tetraploid progeny lineages.</p> <p>Results</p> <p>In both the ncp<it>GS </it>and the <it>PgiC </it>gene tree, haplotype sequences of the diploid <it>A. setacea</it>-2x and <it>A. asplenifolia</it>-2x group into two clades corresponding to the two species, though lineage sorting seems incomplete for the <it>PgiC </it>gene. In contrast, <it>A. collina</it>-4x and its suspected backcross plants show homeologous gene copies: sequences from the same tetraploid individual plant are placed in both diploid clades. Semi-congruent splits of an AFLP Neighbor Net link not only <it>A. collina</it>-4x to both diploid species, but some 4x individuals in a polymorphic population with mixed ploidy levels to <it>A. setacea</it>-2x on one hand and to <it>A. collina</it>-4x on the other, indicating allopolyploid speciation as well as hybridization across ploidal levels.</p> <p>Conclusions</p> <p>The findings of this study clearly demonstrate the hybrid origin of <it>Achillea collina</it>-4x, the ongoing backcrossing between the diploid progenitor and their tetraploid progeny lineages. Such repeated hybridizations are likely the cause of the great genetic and phenotypic variation and ecological differentiation of the polyploid taxa in <it>Achillea millefolium </it>agg.</p

Mixtures of Regression Models for Time-Course Gene Expression Data: Evaluation of Initialization and Random Effects

Finite mixture models are routinely applied to time course microarray data. Due to the complexity and size of this type of data the choice of good starting values plays an important role. So far initialization strategies have only been investigated for data from a mixture of multivariate normal distributions. In this work several initialization procedures are evaluated for mixtures of regression models with and without random effects in an extensive simulation study on different artificial datasets. Finally these procedures are also applied to a real dataset from E. coli

The Realization of Redistribution Layers for FOWLP by Inkjet Printing

The implementation of additive manufacturing technology (e.g., digital printing) to the electronic packaging segment has recently received increasing attention. In almost all types of Fan-out wafer level packaging (FOWLP), redistribution layers (RDLs) are formed by a combination of photolithography, sputtering and plating process. Alternatively, in this study, inkjet-printed RDLs were introduced for FOWLP. In contrast to a subtractive method (e.g., photolithography), additive manufacturing techniques allow depositing the material only where it is desired. In the current study, RDL structures for different embedded modules were realized by inkjet printing and further characterized by electrical examinations. It was proposed that a digital printing process can be a more efficient and lower-cost solution especially for rapid prototyping of RDLs, since several production steps will be skipped, less material will be wasted and the supply chain will be shortened.EC/H2020/737487/EU/(Ultra)Sound Interfaces and Low Energy iNtegrated SEnsors/SILENS

Markov Properties of Electrical Discharge Current Fluctuations in Plasma

Using the Markovian method, we study the stochastic nature of electrical discharge current fluctuations in the Helium plasma. Sinusoidal trends are extracted from the data set by the Fourier-Detrended Fluctuation analysis and consequently cleaned data is retrieved. We determine the Markov time scale of the detrended data set by using likelihood analysis. We also estimate the Kramers-Moyal's coefficients of the discharge current fluctuations and derive the corresponding Fokker-Planck equation. In addition, the obtained Langevin equation enables us to reconstruct discharge time series with similar statistical properties compared with the observed in the experiment. We also provide an exact decomposition of temporal correlation function by using Kramers-Moyal's coefficients. We show that for the stationary time series, the two point temporal correlation function has an exponential decaying behavior with a characteristic correlation time scale. Our results confirm that, there is no definite relation between correlation and Markov time scales. However both of them behave as monotonic increasing function of discharge current intensity. Finally to complete our analysis, the multifractal behavior of reconstructed time series using its Keramers-Moyal's coefficients and original data set are investigated. Extended self similarity analysis demonstrates that fluctuations in our experimental setup deviates from Kolmogorov (K41) theory for fully developed turbulence regime.Comment: 25 pages, 9 figures and 4 tables. V3: Added comments, references, figures and major correction

Characterisation of a highly potent and near pan-neutralising anti-HIV monoclonal antibody expressed in tobacco plants

Background HIV remains one of the most important health issues worldwide, with almost 40 million people living with HIV. Although patients develop antibodies against the virus, its high mutation rate allows evasion of immune responses. Some patients, however, produce antibodies that are able to bind to, and neutralise different strains of HIV. One such ‘broadly neutralising’ antibody is ‘N6’. Identified in 2016, N6 can neutralise 98% of HIV-1 isolates with a median IC50 of 0.066 µg/mL. This neutralisation breadth makes N6 a very promising therapeutic candidate. Results N6 was expressed in a glycoengineered line of N. benthamiana plants (pN6) and compared to the mammalian cell-expressed equivalent (mN6). Expression at 49 mg/kg (fresh leaf tissue) was achieved in plants, although extraction and purification are more challenging than for most plant-expressed antibodies. N-glycoanalysis demonstrated the absence of xylosylation and a reduction in α(1,3)-fucosylation that are typically found in plant glycoproteins. The N6 light chain contains a potential N-glycosylation site, which was modified and displayed more α(1,3)-fucose than the heavy chain. The binding kinetics of pN6 and mN6, measured by surface plasmon resonance, were similar for HIV gp120. pN6 had a tenfold higher affinity for FcγRIIIa, which was reflected in an antibody-dependent cellular cytotoxicity assay, where pN6 induced a more potent response from effector cells than that of mN6. pN6 demonstrated the same potency and breadth of neutralisation as mN6, against a panel of HIV strains. Conclusions The successful expression of N6 in tobacco supports the prospect of developing a low-cost, low-tech production platform for a monoclonal antibody cocktail to control HIV in low-to middle income countries

Mechanisms of cell uptake and toxicity of the anticancer drug cisplatin

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Two major issues which hamper the use of the anticancer drug cisplatin are the development of cancer cell resistance and its nephrotoxicity. One possible mechanism by which resistance is reported to develop is a reduction in drug uptake across the cell membrane. While the passive uptake of cisplatin has long been cited as an important contribution, far greater attention has been given to active modes of uptake, particularly in recent research. Using unilamellar lipid vesicles together with the stopped-flow kinetic method we show here that the permeability coefficient of cisplatin increases significantly with the chloride concentration of the medium. This supports the hypothesis that cisplatin can enter cells via passive permeation through the lipid phase of the membrane, but becomes trapped within the cytoplasm because dissociation of chloride ligands yields a membrane-impermeant positively-charged aqua derivative. This is important evidence for a major role of passive membrane diffusion in the uptake of cisplatin, and suggests that reduced cell uptake is unlikely to be a significant mechanism leading to the development of drug resistance. Studies of rubidium ion uptake into the cytoplasm of Xenopus oocytes via the Na+,K+-ATPase show significant inhibition of this ion pump when cisplatin is present in the cytoplasm. Because Na+,K+-ATPase activity is essential to the survival of all animal cells, e.g. via maintenance of cell volume, and the Na+,K+-ATPase is expressed at particularly high levels within the membranes of kidney tubules where it plays a crucial role in nutrient reabsorption, these results suggest that cisplatin-induced inhibition of the Na+,K+-ATPase is a likely contributing cause for the nephrotoxicity of cisplatin.DFG, EXC 314, Unifying Concepts in Catalysi