136 research outputs found

    The Yang-Mills equations on the universal cosmos

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    AbstractGlobal existence and regularity of solutions for the Yang-Mills equations on the universal cosmos M̃, which has the form R1 × S3 for each of an 8-parameter continuum of factorizations of M̃ as time × space, are treated by general methods. The Cauchy problem in the temporal gauge is globally soluble in its abstract evolutionary form with arbitrary data for the field ⊕ potential in L2,r(S3) ⊕ L2,r + 1(S3), where r is an integer >1 and L2,r denotes the class of sections whose first r derivatives are square-integrable; if r = 1, the problem is soluble locally in time. When r is 3 or more the solution is identifiable with a classical one; if infinite, the solution is in C∞(M̃). These results extend earlier work and approaches [1–5]. Solutions of the equations on Minkowski space-time M0 extend canonically (modulo gauge transformations) to solutions on M̃ provided their Cauchy data are moderately smooth and small near spatial infinity. Precise asymptotic structures for solutions on M0 follow, and in turn imply various decay estimates. Thus the energy in regions uniformly bounded in direction away from the light cone is O(¦x0¦−5), where x0 is the Minkowski time coordinate; analysis solely in M0 [8,9] earlier yielded the estimate O(¦x0¦−2) applicable to the region within the light cone. Similarly it follows that the action integral for a solution of the Yang-Mills equations in M0 is finite, in fact absolutely convergent

    Singular operators on boson fields as forms on spaces of entire functions on Hilbert space

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    AbstractInvariant scales of entire analytic functions on Hilbert space are introduced and applied. Singular operators represented by sesquilinear forms on spaces of regular vectors are given explicit integral representations via kernels that are entire functions on the direct sum of the Hilbert space with its dual. The Weyl (or, exponentiated boson field) operators act smoothly and irreducibly on corresponding spaces of entire functions. Arbitrary symplectic operators on a single-particle Hilbert space are shown to be implementable on the corresponding boson field by appropriate generalized operators

    The Effect of a Type I Photoinitiator on Cure Kinetics and Cell Toxicity in Projection-Microstereolithography

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    AbstractProjection-microstereolithography is an additive manufacturing technique based on the spatially controlled solidification of a liquid photopolymer on exposure to digitally manipulated light patterns. This study presents a methodology to evaluate the effect of a type-I photoinitiator on the reaction kinetics in the process and the cytocompatibility of the produced components. While the reaction speed and degree of conversion were heavily dependent on the applied amount of the initiator, a clear toxic effect was observed with all tested concentrations, and a post-processing step of 7 days was required to leach out the initiator residues

    Dynamics of FitzHugh-Nagumo excitable systems with delayed coupling

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    Small lattices of NN nearest neighbor coupled excitable FitzHugh-Nagumo systems, with time-delayed coupling are studied, and compared with systems of FitzHugh-Nagumo oscillators with the same delayed coupling. Bifurcations of equilibria in N=2 case are studied analytically, and it is then numerically confirmed that the same bifurcations are relevant for the dynamics in the case N>2N>2. Bifurcations found include inverse and direct Hopf and fold limit cycle bifurcations. Typical dynamics for different small time-lags and coupling intensities could be excitable with a single globally stable equilibrium, asymptotic oscillatory with symmetric limit cycle, bi-stable with stable equilibrium and a symmetric limit cycle, and again coherent oscillatory but non-symmetric and phase-shifted. For an intermediate range of time-lags inverse sub-critical Hopf and fold limit cycle bifurcations lead to the phenomenon of oscillator death. The phenomenon does not occur in the case of FitzHugh-Nagumo oscillators with the same type of coupling.Comment: accepted by Phys.Rev.

    What do people do with porn? qualitative research into the consumption, use and experience of pornography and other sexually explicit media

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    This article reviews qualitative research into the consumption of pornography and other sexually explicit media emerging from a range of subject areas. Taking a critique of quantitative methods and a focus on measuring sexual effects and attitudes as a starting point, it considers the proposition that qualitative work is more suited to an examination of the complex social, cultural and political constructions of sexuality. Examining studies into the way men, women and young people see, experience, and use explicit media texts, the article identifies the key findings that have emerged. Qualitative work shows that sexuality explicit media texts are experienced and understood in a variety of ways and evoke strong and often contradictory reactions, not all of which are represented in public debates about pornography. These texts function in a range of different ways, depending on context; as a source of knowledge, a resource for intimate practices, a site for identity construction, and an occasion for performing gender and sexuality. The article reviews these studies and their findings, identifying what they suggest about directions for future research, both in terms of developing methodology and refining approaches to sexuality and media consumption.</p

    Nucleosomes in gene regulation: theoretical approaches

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    This work reviews current theoretical approaches of biophysics and bioinformatics for the description of nucleosome arrangements in chromatin and transcription factor binding to nucleosomal organized DNA. The role of nucleosomes in gene regulation is discussed from molecular-mechanistic and biological point of view. In addition to classical problems of this field, actual questions of epigenetic regulation are discussed. The authors selected for discussion what seem to be the most interesting concepts and hypotheses. Mathematical approaches are described in a simplified language to attract attention to the most important directions of this field

    Corrigendum: Azole-resistance in aspergillus terreusand related species: An emerging problem or a rare phenomenon? (Frontiers in Microbiology (2018) 9 (516) DOI: 10.3389/fmicb.2018.00516)

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    Raquel Sabino was not included as an author in the published article. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated. © 2019 Zoran, Sartori, Sappl, Aigner, Sánchez-Reus, Rezusta, Chowdhary, Taj-Aldeen, Arendrup, Oliveri, Kontoyiannis, Alastruey-Izquierdo, Lagrou, Lo Cascio, Meis, Buzina, Farina, Drogari-Apiranthitou, Grancini, Tortorano, Willinger, Hamprecht, Johnson, Klingspor, Arsic-Arsenijevic, Cornely, Meletiadis, Prammer, Tullio, Vehreschild, Trovato, Lewis, Segal, Rath, Hamal, Rodriguez-Iglesias, Roilides, Arikan-Akdagli, Chakrabarti, Colombo, Fernández, Martin-Gomez, Badali, Petrikkos, Klimko, Heimann, Uzun, Roudbary, de la Fuente, Houbraken, Risslegger, Sabino, Lass-Flörl and Lackner
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