The possibility that methane hydrates form in sodium dodecyl sulfate (SDS) water solutions without the help of micelles formation has been investigated. To asses whether micelles are needed for the hydrate to form only one SDS molecule has been considered. To figure out the possible mechanism through which the SDS promotes the formation of methane clathrate the dynamics of CH(4) solvation in the presence and absence of the surfactant molecule is monitored. To carry out the dynamical calculations, the SDS-H(2)O, SDS-CH(4), and CH(4)-H(2)O interactions were described using a recently proposed model potential. The adopted model leverages both on the decomposition of the molecular polarizability in effective components associated with the interaction centers distributed on the molecular frame and on the use of an improved Lennard-Jones functional form to represent the effective pair interaction energies. Molecular dynamics simulations performed on such potential, contrary to some earlier assumptions, do not support mechanisms requiring the formation of micelles as suggested by the findings of more recent experiments.
Foundations and structure of the building blocks of GEMS, the ab initio molecular simulator designed for implementation on the EGEE computing Grid, are analyzed. The impact of the computational characteristics of the codes composing its blocks (the calculation of the ab initio potential energy values, the integration of the dynamics equations of the nuclear motion, and the statistical averaging of microscopic information to evaluate the relevant observable properties) on their Grid implementation when using rigorous ab initio quantum methods are discussed. The requests prompted by this approach for new computational developments are also examined by considering the present implementation of the simulator that is specialized in atom diatom reactive exchange processes.
A new six-dimensional (6D) global potential energy surface (PES) is proposed for the full range description of the interaction of the N2(1Σg+)+N2(1Σg+) system governing collisional processes, including N atom exchange. The related potential energy values were determined using high-level ab initio methods. The calculations were performed at a coupled-cluster with single and double and perturbative triple excitations level of theory in order to have a first full range picture of the PES. Subsequently, in order to accurately describe the stretching of the bonds of the two interacting N2 molecules by releasing the constraints of being considered as rigid rotors, for the same molecular geometries higher level of theory multi reference calculations were performed. Out of the calculated values a 6D 4-atoms global PES was produced for use in dynamical calculations. The ab initio calculations were made possible by the combined use of High Throughput Computing and High Performance Computing techniques within the frame of a computing grid empowered molecular simulator.
In this paper we propose a distributed architecture to provide machine learning practitioners with a set of tools and cloud services that cover the whole machine learning development cycle: ranging from the models creation, training, validation and testing to the models serving as a service, sharing and publication. In such respect, the DEEP-Hybrid-DataCloud framework allows transparent access to existing e-Infrastructures, effectively exploiting distributed resources for the most compute-intensive tasks coming from the machine learning development cycle. Moreover, it provides scientists with a set of Cloud-oriented services to make their models publicly available, by adopting a serverless architecture and a DevOps approach, allowing an easy share, publish and deploy of the developed models. INDEX TERMS Cloud computing, computers and information processing, deep learning, distributed computing, machine learning, serverless architectures.
The endoscope assisted transoral approach allows a better surgical control of the CVJ. It provides a better CVJ exposure, in sagittal and transverse planes, providing a larger working channel and an easier manoeuvrability. The transnasal approach is limited in caudal direction down to the NPL, otherwise the transoral approach is limited in the rostral direction with a maximum to the foramen magnum in normal specimen. In every individual case, pros and cons of the appropriate approach have to be taken into account as well as the choice of a combined transnasal and transoral approaches strategy.
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