1,721,125 research outputs found
Thermodynamics and kinetics of ion translocation in the human wild-type and E-1' A α7 nicotinic receptor
No full textWe use an all-atom model of the human nicotinic acetylcholine receptor α7 in a conductive conformation, to provide the first available mapping of the potential of mean force for the ion translocation across the channel. The modeling is based on MD simulations combined with the milestoning method with Voronoi tessellation. The quality of the protein model and description is confirmed by the agreement with experimental data for proteins of the same family. The specific mutation E-1' A at the cytoplasmatic filter is here shown to strongly affect both sodium and chloride permeation, leading to a complete inversion of selectivit
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Computational modeling of geminate recombination and energy relaxation of nitric oxide in myoglobin under constant illumination.
No full text
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Multiphoton Absorption of Myoglobin–Nitric Oxide Complex: Relaxation by D-NEMD of a Stationary State
No full textThe photodissociation and geminate recombination of nitric oxide in myoglobin, under continuous illumination, is modeled computationally. The relaxation of the photon energy into the protein matrix is also considered in a single simulation scheme that mimics a complete experimental setup. The dynamic approach to non-equilibrium molecular dynamics is used, starting from a steady state, to compute its relaxation to equilibrium. Simulations are conducted for the native form of sperm whale myoglobin and for two other mutants, V68W and L29F, illustrating a fair diversity of spatial and temporal geminate recombination processes. Energy flow to the heme and immediate protein environment provide hints to allostery. In particular, a pathway of energy flow between the heme and the FG loop is illustrated. Although the simulations were conducted for myoglobin only, the thermal fluctuations of the FG corner are in agreement with the large structural shifts of FG during the allosteric transition of tetrameric hemoglobin
A microplane model for plane-stress masonry structures
No full textA microplane model is presented for the nonlinear finite element analysis of masonry structures. The model is developed for plane-stress problems. For each microplane a damage constitutive law is defined which correlates normal and tangential components of the strain vector acting on the specific microplane with the corresponding stress vector components. Some numerical analyses are performed on masonry panels and the results compared with experimental data
A possible desensitized state conformation of the human alpha7 nicotinic receptor: A molecular dynamics study
No full textThe determination of the conformational states corresponding to diverse functional roles of ligand gated ion channels is subject of intense investigation with various techniques, from X-rays structure determination to electrophysiology and computational modeling. Even with a certain number of structures becoming recently available, only few major structural features distinguishing conductive open channel from the non conductive resting protein have been highlighted, while high-resolution details are still missing. The characterization of the desensitized conformation(s) is even more complex, and only few specific characteristics have been identified. Furthermore, experimental data provide conflicting information for different ion channels, adding further complexity to the topic. Desensitization is defined as the transition of the agonist-bound open channel into an ion channel configuration inactive even in the presence of agonists. In this work, we analyze a conformation corresponding to a non conductive state obtained via molecular dynamics simulations of a homology model of the human α7 nicotinic receptor complexed with agonists. We highlight some characteristics that could associate it to a desensitized state. The obtained structure is assessed against experimental data for other ligand gated ion channels that have been putatively associated to active, inactive and desensitized conditions
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