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Search Results: 1 - 10 of 406010 matches for " Christoph M?hl "
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Coupling of cytoplasm and adhesion dynamics determines cell polarization and locomotion
Wolfgang Alt,Martin Bock,Christoph Mhl
Quantitative Biology , 2009,
Abstract: Observations of single epidermal cells on flat adhesive substrates have revealed two distinct morphological and functional states, namely a non-migrating symmetric unpolarized state and a migrating asymmetric polarized state. These states are characterized by different spatial distributions and dynamics of important biochemical cell components: F-actin and myosin-II form the contractile part of the cytoskeleton, and integrin receptors in the plasma membrane connect F-actin filaments to the substratum. In this way, focal adhesion complexes are assembled, which determine cytoskeletal force transduction and subsequent cell locomotion. So far, physical models have reduced this phenomenon either to gradients in regulatory control molecules or to different mechanics of the actin filament system in different regions of the cell. Here we offer an alternative and self-organizational model incorporating polymerization, pushing and sliding of filaments, as well as formation of adhesion sites and their force dependent kinetics. All these phenomena can be combined into a non-linearly coupled system of hyperbolic, parabolic and elliptic differential equations. Aim of this article is to show how relatively simple relations for the small-scale mechanics and kinetics of participating molecules may reproduce the emergent behavior of polarization and migration on the large-scale cell level.
Laser spectroscopy and cooling of Yb+ ions on a deep-UV transition
Hendrik M. Meyer,Matthias Steiner,Lothar Ratschbacher,Christoph Zipkes,Michael K?hl
Physics , 2011, DOI: 10.1103/PhysRevA.85.012502
Abstract: We perform laser spectroscopy of Yb+ ions on the 4f14 6s 2S_{1/2} - 4f13 5d 6s 3D[3/2]_{1/2} transition at 297 nm. The frequency measurements for 170Yb+, 172Yb+, 174Yb+, and 176Yb+ reveal the specific mass shift as well as the field shifts. In addition, we demonstrate laser cooling of Yb+ ions using this transition and show that light at 297 nm can be used as the second step in the photoionization of neutral Yb atoms.
Comprehensive Postmortem Analyses of Intestinal Microbiota Changes and Bacterial Translocation in Human Flora Associated Mice
Markus M. Heimesaat, Silvia Boelke, André Fischer, Lea-Maxie Haag, Christoph Loddenkemper, Anja A. Kühl, Ulf B. G?bel, Stefan Bereswill
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040758
Abstract: Background Postmortem microbiological examinations are performed in forensic and medical pathology for defining uncertain causes of deaths and for screening of deceased tissue donors. Interpretation of bacteriological data, however, is hampered by false-positive results due to agonal spread of microorganisms, postmortem bacterial translocation, and environmental contamination. Methodology/Principal Findings We performed a kinetic survey of naturally occurring postmortem gut flora changes in the small and large intestines of conventional and gnotobiotic mice associated with a human microbiota (hfa) applying cultural and molecular methods. Sacrificed mice were kept under ambient conditions for up to 72 hours postmortem. Intestinal microbiota changes were most pronounced in the ileal lumen where enterobacteria and enterococci increased by 3–5 orders of magnitude in conventional and hfa mice. Interestingly, comparable intestinal overgrowth was shown in acute and chronic intestinal inflammation in mice and men. In hfa mice, ileal overgrowth with enterococci and enterobacteria started 3 and 24 hours postmortem, respectively. Strikingly, intestinal bacteria translocated to extra-intestinal compartments such as mesenteric lymphnodes, spleen, liver, kidney, and cardiac blood as early as 5 min after death. Furthermore, intestinal tissue destruction was characterized by increased numbers of apoptotic cells and neutrophils within 3 hours postmortem, whereas counts of proliferative cells as well as T- and B-lymphocytes and regulatory T-cells decreased between 3 and 12 hours postmortem. Conclusions/Significance We conclude that kinetics of ileal overgrowth with enterobacteria and enterococci in hfa mice can be used as an indicator for compromized intestinal functionality and for more precisely defining the time point of death under defined ambient conditions. The rapid translocation of intestinal bacteria starting within a few minutes after death will help to distinguish between relevant bacteria and secondary contaminants thus providing important informations for routine applications and future studies in applied microbiology, forensic pathology, and criminal medicine.
Anti-Inflammatory Effects of Resveratrol, Curcumin and Simvastatin in Acute Small Intestinal Inflammation
Stefan Bereswill,Melba Mu?oz,André Fischer,Rita Plickert,Lea-Maxie Haag,Bettina Otto,Anja A. Kühl,Christoph Loddenkemper,Ulf B. G?bel,Markus M. Heimesaat
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015099
Abstract: The health beneficial effects of Resveratrol, Curcumin and Simvastatin have been demonstrated in various experimental models of inflammation. We investigated the potential anti-inflammatory and immunomodulatory mechanisms of the above mentioned compounds in a murine model of hyper-acute Th1-type ileitis following peroral infection with Toxoplasma gondii.
Habermas e a educa??o: racionalidade comunicativa, diagnóstico crítico e emancipa??o
Mühl, Eldon Henrique;
Educa??o & Sociedade , 2011, DOI: 10.1590/S0101-73302011000400008
Abstract: this work tries to clarify the impacts of the theory of communicative rationality and habermas' theory of modernity on the educational field. afer developing the main ideas of both theories, it presents a brief diagnostic of the current crisis of rationality and education. its references are two concepts that are central to the author: the world of life and the system. the text then analyzes the implications of the communicative theory in the educational field and evaluates the efficiency of the german thinker's theses from a pedagogical point of view. it highlights both the pedagogical consequences of the philosophical change from the paradigm of the philosophy of the subject to that of intersubjectivity and the role philosophy played in this reconstruction in order to found a critical pedagogical proposal based on habermas' theory of communicative action.
Novel Murine Infection Models Provide Deep Insights into the “Ménage à Trois” of Campylobacter jejuni, Microbiota and Host Innate Immunity
Stefan Bereswill,André Fischer,Rita Plickert,Lea-Maxie Haag,Bettina Otto,Anja A. Kühl,Javid I. Dashti,Andreas E. Zautner,Melba Mu?oz,Christoph Loddenkemper,Uwe Gro?,Ulf B. G?bel,Markus M. Heimesaat
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0020953
Abstract: Although Campylobacter jejuni-infections have a high prevalence worldwide and represent a significant socioeconomic burden, it is still not well understood how C. jejuni causes intestinal inflammation. Detailed investigation of C. jejuni-mediated intestinal immunopathology is hampered by the lack of appropriate vertebrate models. In particular, mice display colonization resistance against this pathogen.
SABA: A Testbed for a Real-Time MIMO System
Borkowski Daniel,Brühl Lars,Degen Christoph,Keusgen Wilhem
EURASIP Journal on Advances in Signal Processing , 2006,
Abstract: The growing demand for high data rates for wireless communication systems leads to the development of new technologies to increase the channel capacity thus increasing the data rate. MIMO (multiple-input multiple-output) systems are best qualified for these applications. In this paper, we present a MIMO test environment for high data rate transmissions in frequency-selective environments. An overview of the testbed is given, including the analyzed algorithms, the digital signal processing with a new highly parallel processor to perform the algorithms in real time, as well as the analog front-ends. A brief overview of the influence of polarization on the channel capacity is given as well.
A trapped single ion inside a Bose-Einstein condensate
Christoph Zipkes,Stefan Palzer,Carlo Sias,Michael K?hl
Physics , 2010, DOI: 10.1038/nature08865
Abstract: Improved control of the motional and internal quantum states of ultracold neutral atoms and ions has opened intriguing possibilities for quantum simulation and quantum computation. Many-body effects have been explored with hundreds of thousands of quantum-degenerate neutral atoms and coherent light-matter interfaces have been built. Systems of single or a few trapped ions have been used to demonstrate universal quantum computing algorithms and to detect variations of fundamental constants in precision atomic clocks. Until now, atomic quantum gases and single trapped ions have been treated separately in experiments. Here we investigate whether they can be advantageously combined into one hybrid system, by exploring the immersion of a single trapped ion into a Bose-Einstein condensate of neutral atoms. We demonstrate independent control over the two components within the hybrid system, study the fundamental interaction processes and observe sympathetic cooling of the single ion by the condensate. Our experiment calls for further research into the possibility of using this technique for the continuous cooling of quantum computers. We also anticipate that it will lead to explorations of entanglement in hybrid quantum systems and to fundamental studies of the decoherence of a single, locally controlled impurity particle coupled to a quantum environment.
Quantum transport through a Tonks-Girardeau gas
Stefan Palzer,Christoph Zipkes,Carlo Sias,Michael K?hl
Physics , 2009, DOI: 10.1103/PhysRevLett.103.150601
Abstract: We investigate the propagation of spin impurity atoms through a strongly interacting one-dimensional Bose gas. The initially well localized impurities are accelerated by a constant force, very much analogous to electrons subject to a bias voltage, and propagate as a one-dimensional impurity spin wave packet. We follow the motion of the impurities in situ and characterize the interaction induced dynamics. We observe a very complex non-equilibrium dynamics, including the emergence of large density fluctuations in the remaining Bose gas, and multiple scattering events leading to dissipation of the impurity's motion.
Controlling chemical reactions of a single particle
Lothar Ratschbacher,Christoph Zipkes,Carlo Sias,Michael K?hl
Physics , 2012, DOI: 10.1038/nphys2373
Abstract: The control of chemical reactions is a recurring theme in physics and chemistry. Traditionally, chemical reactions have been investigated by tuning thermodynamic parameters, such as temperature or pressure. More recently, physical methods such as laser or magnetic field control have emerged to provide completely new experimental possibilities, in particular in the realm of cold collisions. The control of reaction pathways is also a critical component to implement molecular quantum information processing. For these undertakings, single particles provide a clean and well-controlled experimental system. Here, we report on the experimental tuning of the exchange reaction rates of a single trapped ion with ultracold neutral atoms by exerting control over both their quantum states. We observe the influence of the hyperfine interaction on chemical reaction rates and branching ratios, and monitor the kinematics of the reaction products. These investigations advance chemistry with single trapped particles towards achieving quantum-limited control of chemical reactions and indicate limits for buffer gas cooling of single ion clocks.
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