228 research outputs found
Constructing exact representations of quantum many-body systems with deep neural networks
We develop a constructive approach to generate artificial neural networks
representing the exact ground states of a large class of many-body lattice
Hamiltonians. It is based on the deep Boltzmann machine architecture, in which
two layers of hidden neurons mediate quantum correlations among physical
degrees of freedom in the visible layer. The approach reproduces the exact
imaginary-time Hamiltonian evolution, and is completely deterministic. In turn,
compact and exact network representations for the ground states are obtained
without stochastic optimization of the network parameters. The number of
neurons grows linearly with the system size and total imaginary time,
respectively. Physical quantities can be measured by sampling configurations of
both physical and neuron degrees of freedom. We provide specific examples for
the transverse-field Ising and Heisenberg models by implementing efficient
sampling. As a compact, classical representation for many-body quantum systems,
our approach is an alternative to the standard path integral, and it is
potentially useful also to systematically improve on numerical approaches based
on the restricted Boltzmann machine architecture
Asynchronous Rhythm of Steroidogenic Factor 1 and Period Homolog 2 mRNA Expression in Mouse Y1 Adrenocorticol Tumor Cells
The relationship between the expression of Steroidogenic factor 1 (Sf1) and the circadian-related gene, period homolog 2 (Per2), in the adrenal cortex is still unknown. We show here that in Y1 adrenocortical tumor cells, expression of steroidogenic-related genes such as P450scc mRNA and Sf1 mRNA were asynchronous with Per2 mRNA. SF1 promoter analyses showed that the E-box element functions in a rhythmic pattern. Rhythmic expression of Upstream factor 1 mRNA, correlated well with Sf1 mRNA expression. We propose that tumorigenesis of adrenocortical lesions cause disruption of synchronous expression of steroidogenic-related and circadian-related genes
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