1,452 research outputs found

    MinE conformational switching confers robustness on self-organized Min protein patterns

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    Protein patterning is vital for many fundamental cellular processes. This raises two intriguing questions: Can such intrinsically complex processes be reduced to certain core principles and, if so, what roles do the molecular details play in individual systems? A prototypical example for protein patterning is the bacterial Min system, in which self-organized pole-to-pole oscillations of MinCDE proteins guide the cell division machinery to midcell. These oscillations are based on cycling of the ATPase MinD and its activating protein MinE between the membrane and the cytoplasm. Recent biochemical evidence suggests that MinE undergoes a reversible, MinD-dependent conformational switch from a latent to a reactive state. However, the functional relevance of this switch for the Min network and pattern formation remains unclear. By combining mathematical modeling and in vitro reconstitution of mutant proteins, we dissect the two aspects of MinE's switch, persistent membrane binding and a change in MinE's affinity for MinD. Our study shows that the MinD-dependent change in MinE's binding affinity for MinD is essential for patterns to emerge over a broad and physiological range of protein concentrations. Mechanistically, our results suggest that conformational switching of an ATPase-activating protein can lead to the spatial separation of its distinct functional states and thereby confer robustness on an intracellular protein network with vital roles in bacterial cell division

    Space of State Vectors in PT Symmetrical Quantum Mechanics

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    Space of states of PT symmetrical quantum mechanics is examined. Requirement that eigenstates with different eigenvalues must be orthogonal leads to the conclusion that eigenfunctions belong to the space with an indefinite metric. The self consistent expressions for the probability amplitude and average value of operator are suggested. Further specification of space of state vectors yield the superselection rule, redefining notion of the superposition principle. The expression for the probability current density, satisfying equation of continuity and vanishing for the bound state, is proposed.Comment: Revised version, explicit expressions for average values and probability amplitude adde

    Improved limits on nuebar emission from mu+ decay

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    We investigated mu+ decays at rest produced at the ISIS beam stop target. Lepton flavor (LF) conservation has been tested by searching for \nueb via the detection reaction p(\nueb,e+)n. No \nueb signal from LF violating mu+ decays was identified. We extract upper limits of the branching ratio for the LF violating decay mu+ -> e+ \nueb \nu compared to the Standard Model (SM) mu+ -> e+ nue numub decay: BR < 0.9(1.7)x10^{-3} (90%CL) depending on the spectral distribution of \nueb characterized by the Michel parameter rho=0.75 (0.0). These results improve earlier limits by one order of magnitude and restrict extensions of the SM in which \nueb emission from mu+ decay is allowed with considerable strength. The decay \mupdeb as source for the \nueb signal observed in the LSND experiment can be excluded.Comment: 10 pages, including 1 figure, 1 tabl

    Increasing Dominance - the Role of Advertising, Pricing and Product Design

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    Despite the empirical relevance of advertising strategies in concentrated markets, the economics literature is largely silent on the effect of persuasive advertising strategies on pricing, market structure and increasing (or decreasing) dominance. In a simple model of persuasive advertising and pricing with differentiated goods, we analyze the interdependencies between ex-ante asymmetries in consumer appeal, advertising and prices. Products with larger initial appeal to consumers will be advertised more heavily but priced at a higher level - that is, advertising and price discounts are strategic substitutes for products with asymmetric initial appeal. We find that the escalating effect of advertising dominates the moderating effect of pricing so that post-competition market shares are more asymmetric than pre-competition differences in consumer appeal. We further find that collusive advertising (but competitive pricing) generates the same market outcomes, and that network effects lead to even more extreme market outcomes, both directly and via the effect on advertising

    Ambient habitat noise and vibration at the Georgia Aquarium

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    Underwater and in-air noise evaluations were completed in performance pool systems at Georgia Aquarium under normal operating conditions and with performance sound tracks playing. Ambient sound pressure levels at in-pool locations, with corresponding vibration measures from life support system (LSS) pumps, were measured in operating configurations, from shut down to full operation. Results indicate noise levels in the low frequency ranges below 100ā€‰Hz were the highest produced by the LSS relative to species hearing thresholds. The LSS had an acoustic impact of about 10ā€‰dB at frequencies up to 700ā€‰Hz, with a 20ā€‰dB re 1ā€‰Ī¼Pa impact above 1000ā€‰Hz

    Aortomonoiliac Endografting after Failed Endovascular Aneurysm Repair: Indications and Long-term Results

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    AbstractObjectivesTo present long-term results of endoleak/endograft migration treatment by aortomonoiliac (AMI) endografting after failed endovascular aneurysm repair (EVAR) of infrarenal abdominal aortic aneurysms.DesignPost hoc analysis of a prospectively gathered database at a tertiary care university hospital.Materials and methodsFrom March 1995 to November 2010, 23 patients were identified who underwent modification into AMI configuration after failed elective EVAR. Major causes for modification were type I (with/without endograft migration) or type III endoleaks with aneurysm expansion. An average increase in aneurysm size of 1.6Ā cm (range: āˆ’1.5 to 10.5Ā cm) since initial aneurysm treatment was observed. Interventional outcomes and long-term results were recorded for analysis.ResultsTechnical success rate of AMI endografting was 95.65% (nĀ =Ā 22). All except two endoleaks could be successfully sealed with this manoeuvre (94.44%). Median time to modification was 5.3 years (interquartile range Q1ā€“Q3: 1.3ā€“9.3 years). No intra-operative conversion to open surgery was necessary and mortality was 0%. Median follow-up was 44 months (interquartile range Q1ā€“Q3: 17ā€“69 months).ConclusionsTreatment of graft-related endoleaks/endograft migration by AMI endografting after failed EVAR represents a safe and feasible procedure. This approach broadens the minimal invasive opportunities of aneurysm treatment, and open surgical conversion may be avoided except in selected patients

    The politics of the digital single market:Culture vs. competition vs. copyright

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    This paper examines the implications for European music culture of the European Unionā€™s Digital Single Market strategy. It focuses on the regulatory framework being created for the management of copyright policy, and in particular the role played by Collective Management Organisations (or Collecting Societies). One of the many new opportunities created by digitalization has been the music streaming services. These depend on consumers being able to access music wherever they are, but such a system runs counter to the management of rights on a national basis and through collecting organisations who act as monopolies within their own territories. The result has been ā€˜geo-blockingā€™. The EU has attempted to resolve this problem in a variety of ways, most recently in a Directive designed to reform the CMOs. In this paper, we document these various efforts, showing them to be motivated by a deep-seated and persisting belief in the capacity of ā€˜competitionā€™ to resolve problems that, we argue, actually lie elsewhere - in copyright policy itself. The result is that the EUā€™s intervention fails to address its core concern and threatens the diversity of European music culture by rewarding those who are already commercially successful
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