Sanchez J.M.,University of Texas at Austin |
Mohri T.,Sendai University
Computational Materials Science | Year: 2016
In this paper we obtain approximate solutions to the Cluster Variation free energy by carrying out a cluster expansion of the probabilities appearing in the free energy functional in terms of concentration-dependent basis functions, and by truncating the expansion at different cluster levels prior to minimization. We show that a significant improvement over the Bragg-Williams approximation can be achieved by truncating the expansion of the cluster probabilities at relatively small clusters, thus dramatically reducing the number of equations that need to be solved in order to minimize the free energy. Furthermore, the free energy functional in the Cluster Variation Method offers a well-controlled case study to infer the effects of truncating the expansion of the energy of alloy formation in the commonly used Cluster Expansion method, versus the effects of truncating the expansion when using a concentration-dependent basis. Examples of the approach are given for simple Ising models for fcc- and bcc-based prototype alloy systems. © 2016 Elsevier B.V.
Aso Y.,Howard Hughes Medical Institute |
Hattori D.,Howard Hughes Medical Institute |
Yu Y.,Howard Hughes Medical Institute |
Johnston R.M.,Howard Hughes Medical Institute |
And 7 more authors.
eLife | Year: 2014
We identified the neurons comprising the Drosophila mushroom body (MB), an associative center in invertebrate brains, and provide a comprehensive map describing their potential connections. Each of the 21 MB output neuron (MBON) types elaborates segregated dendritic arbors along the parallel axons of ∼2000 Kenyon cells, forming 15 compartments that collectively tile the MB lobes. MBON axons project to five discrete neuropils outside of the MB and three MBON types form a feedforward network in the lobes. Each of the 20 dopaminergic neuron (DAN) types projects axons to one, or at most two, of the MBON compartments. Convergence of DAN axons on compartmentalized Kenyon cell-MBON synapses creates a highly ordered unit that can support learning to impose valence on sensory representations. The elucidation of the complement of neurons of the MB provides a comprehensive anatomical substrate from which one can infer a functional logic of associative olfactory learning and memory.
Cotton L.M.,University of Virginia |
Rodriguez C.M.,Virginia Commonwealth University |
Suzuki K.,Sendai University |
Orgebin-Crist M.-C.,Center for Reproductive Biology Research |
Hinton B.T.,University of Virginia
Molecular Reproduction and Development | Year: 2010
Protection of cells from osmotic stress is crucial for their survival. Exposure to high osmolarity promotes rapid diffusion of water across cell membranes, dramatically increasing cellular ionic strength, leading to disruption of key proteins/DNA resulting in cell-cycle arrest and apoptosis. The luminal microenvironment of the epididymis is hypertonic; therefore, epididymal cells adapt to the higher osmolarity by accumulating organic osmolytes, such as L-carnitine. Osmolytes do not perturb cells when accumulated in high concentrations, nor do they affect key proteins or damage DNA. Therefore, osmolytes and their transporters are crucial for cell survival. Transporters that are responsible for the accumulation of organic osmolytes have been shown to be regulated at the transcriptional level by hypertonicity. The present study examines the gene expression of known osmoprotective/stress genes in epididymal cells exposed to changes in tonicity. We demonstrate that the osmoprotective/stress pathways present in other organs, such as the kidney, operate in the epididymis, potentially aiding in the protection of its luminal cells and spermatozoa. Further, it was also seen that OCTN2, a transporter that is thought to be responsible for the accumulation of L-carnitine in the epididymal lumen, is regulated in response to changes in tonicity. © 2009 Wiley-Liss, Inc.
Kuramitsu Y.,Osaka University |
Sakawa Y.,Osaka University |
Dono S.,Osaka University |
Gregory C.D.,Ecole Polytechnique - Palaiseau |
And 12 more authors.
Physical Review Letters | Year: 2012
We report the experimental results of a turbulent electric field driven by Kelvin-Helmholtz instability associated with laser produced collisionless shock waves. By irradiating an aluminum double plane target with a high-power laser, counterstreaming plasma flows are generated. As the consequence of the two plasma interactions, two shock waves and the contact surface are excited. The shock electric field and transverse modulation of the contact surface are observed by proton radiography. Performing hydrodynamic simulations, we reproduce the time evolutions of the reverse shocks and the transverse modulation driven by Kelvin-Helmholtz instability. © 2012 American Physical Society.
Oba T.,Nippon Telegraph and Telephone |
Oba T.,Sendai University |
Hori T.,Nippon Telegraph and Telephone |
Nakamura A.,Nippon Telegraph and Telephone |
Ito A.,Sendai University
IEEE Transactions on Audio, Speech and Language Processing | Year: 2012
Discriminative training has received a lot of attention from both the machine learning and speech recognition communities. The idea behind the discriminative approach is to construct a model that distinguishes correct samples from incorrect samples, while the conventional generative approach estimates the distributions of correct samples. We propose a novel discriminative training method and apply it to a language model for reranking speech recognition hypotheses. Our proposed method has round-robin duel discrimination (R2D2) criteria in which all the pairs of sentence hypotheses including pairs of incorrect sentences are distinguished from each other, taking their error rate into account. Since the objective function is convex, the global optimum can be found through a normal parameter estimation method such as the quasi-Newton method. Furthermore, the proposed method is an expansion of the global conditional log-linear model whose objective function corresponds to the conditional random fields. Our experimental results show that R2D2 outperforms conventional methods in many situations, including different languages, different feature constructions and different difficulties. © 2011 IEEE.