Computational Imaging Group, Department of Electrical and Computer Engineering, University of Canterbury, Christchurch, New Zealand.
Published: March 2014
AI Article Synopsis
Article Abstract
X-ray free-electron laser diffraction patterns from protein nanocrystals provide information on the diffracted amplitudes between the Bragg reflections, offering the possibility of direct phase retrieval without the use of ancillary experimental diffraction data [Spence et al. (2011). Opt. Express, 19, 2866-2873]. The estimated continuous transform is highly noisy however [Chen et al. (2014). Acta Cryst. A70, 143-153]. This second of a series of two papers describes a data-selection strategy to ameliorate the effects of the high noise levels and the subsequent use of iterative phase-retrieval algorithms to reconstruct the electron density. Simulation results show that employing such a strategy increases the noise levels that can be tolerated.
In keeping with the historical focus of this special issue of Hippocampus, this paper reviews the history of my development of the SPEAR model. The SPEAR model proposes that separate phases of encoding and retrieval (SPEAR) allow effective storage of multiple overlapping associative memories in the hippocampal formation and other cortical structures. The separate phases for encoding and retrieval are proposed to occur within different phases of theta rhythm with a cycle time on the order of 125 ms.
Hopfield neural networks (HNNs) promise broad applications in areas such as combinatorial optimization, memory storage, and pattern recognition. Among various implementations, optical HNNs are particularly interesting because they can take advantage of fast optical matrix-vector multiplications. Yet their studies so far have mostly been on the theoretical side, and the effects of optical imperfections and robustness against memory errors remain to be quantified.
In order to address the issue of low effective bandwidth ratio in off-axis digital holography, which is caused by the impact of zeroth- and first-order terms on the first-order term, an improved digital holographic reconstruction algorithm by zeroth-order term elimination based on the Riesz transform is proposed in this paper. First, an off-axis hologram is convolved with the Riesz kernels. Then, in the spectrum, the zeroth-order term is effectively eliminated by a singularity at the origin of the Riesz kernels, which can improve the effective bandwidth ratio and make the best use of the bandwidth.
G protein-coupled receptor 139 (GPR139), a highly conserved orphan receptor, is predominantly expressed in the habenula of vertebrate species. Habenula is an ancient epithalamic structure, which is critical to comprehending adaptive behaviors in vertebrates. We have previously demonstrated the role of GPR139 agonists in fear-associated decision-making processes in zebrafish.
Background: Understanding drug addiction as a disorder of maladaptive learning, where drug-associated or environmental cues trigger drug cravings and seeking, is crucial for developing effective treatments. Actin polymerization, a biochemical process, plays a crucial role in drug-related memory formation, particularly evident in conditioned place preference (CPP) paradigms involving drugs like morphine and methamphetamine. However, the role of actin polymerization in the reconsolidation of heroin-associated memories remains understudied.
