3,978 research outputs found
The upper critical magnetic field of holographic superconductor with conformally invariant power-Maxwell electrodynamics
The properties of -dimensional -wave holographic superconductor in
the presence of power-Maxwell field is explored. We study the probe limit in
which the scalar and gauge fields do not backreact on the background geometry.
Our study is based on the matching of solutions on the boundary and on the
horizon at some intermediate point. At first, the case without external
magnetic field is considered, and the critical temperature is obtained in terms
of the charge density, the dimensionality, and the power-Maxwell exponent.
Then, a magnetic field is turned on in the -dimensional bulk which can
influence the -dimensional holographic superconductor at the boundary.
The phase behavior of the corresponding holographic superconductor is obtained
by computing the upper critical magnetic field in the presence of power-Maxwell
electrodynamics, characterized by the power exponent . Interestingly, it is
observed that in the presence of magnetic field, the physically acceptable
phase behavior of the holographic superconductor is obtained for ,
which guaranties the conformal invariance of the power-Maxwell Lagrangian. The
case of physical interest in five spacetime dimensions (, and ) is
considered in detail, and compared with the results obtained for the usual
Maxwell electrodynamics in the same dimensions.Comment: 12 pages, 1 table, 5 figure
REinforcement learning based Adaptive samPling: REAPing Rewards by Exploring Protein Conformational Landscapes
One of the key limitations of Molecular Dynamics simulations is the
computational intractability of sampling protein conformational landscapes
associated with either large system size or long timescales. To overcome this
bottleneck, we present the REinforcement learning based Adaptive samPling
(REAP) algorithm that aims to efficiently sample conformational space by
learning the relative importance of each reaction coordinate as it samples the
landscape. To achieve this, the algorithm uses concepts from the field of
reinforcement learning, a subset of machine learning, which rewards sampling
along important degrees of freedom and disregards others that do not facilitate
exploration or exploitation. We demonstrate the effectiveness of REAP by
comparing the sampling to long continuous MD simulations and least-counts
adaptive sampling on two model landscapes (L-shaped and circular), and
realistic systems such as alanine dipeptide and Src kinase. In all four
systems, the REAP algorithm consistently demonstrates its ability to explore
conformational space faster than the other two methods when comparing the
expected values of the landscape discovered for a given amount of time. The key
advantage of REAP is on-the-fly estimation of the importance of collective
variables, which makes it particularly useful for systems with limited
structural information
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