Brain-mediated Transfer Learning of Convolutional Neural Networks

The human brain can effectively learn a new task from a small number of samples, which indicate that the brain can transfer its prior knowledge to solve tasks in different domains. This function is analogous to transfer learning (TL) in the field of machine learning. TL uses a well-trained feature space in a specific task domain to improve performance in new tasks with insufficient training data. TL with rich feature representations, such as features of convolutional neural networks (CNNs), shows high generalization ability across different task domains. However, such TL is still insufficient in making machine learning attain generalization ability comparable to that of the human brain. To examine if the internal representation of the brain could be used to achieve more efficient TL, we introduce a method for TL mediated by human brains. Our method transforms feature representations of audiovisual inputs in CNNs into those in activation patterns of individual brains via their association learned ahead using measured brain responses. Then, to estimate labels reflecting human cognition and behavior induced by the audiovisual inputs, the transformed representations are used for TL. We demonstrate that our brain-mediated TL (BTL) shows higher performance in the label estimation than the standard TL. In addition, we illustrate that the estimations mediated by different brains vary from brain to brain, and the variability reflects the individual variability in perception. Thus, our BTL provides a framework to improve the generalization ability of machine-learning feature representations and enable machine learning to estimate human-like cognition and behavior, including individual variability

Relational Network of People Constructed on the Basis of Similarity of Brain Activities.

The relational network of people (RNP) model has been attracting the interest of not only researchers but also industrial engineers. RNP can be constructed from friend lists in online social networking services (SNSs) and from inter-contact logs between individuals. One of the killer applications of RNP is the prediction of user demands, which is key to maximizing user satisfaction in content delivery services such as video streaming and video advertising. It is well known that an RNP representing social closeness between individuals (a so-called social network) can estimate user preferences simply, as we expect that people close to each other will have similar preferences. However, although there are many metrics that enable the social closeness between individuals to be measured, it is unclear which metric is best suited for individual services. Therefore, this paper introduces a new approach based on brain imaging. Brain imaging using functional Magnetic Resonance Imaging (fMRI) is powerful because it enables us to directly observe how a video content stimulates the brains of individual people. We propose a brain imaging-based RNP that represents the similarity of video-evoked brain activities between people as a network graph. We show an application scenario featuring predictive content delivery using the proposed RNP in which, when a user shows interest in a video content in some way, other users close to him or her can be expected to also be interested in it because their brain activities are correlated. Through numerical evaluation using multiple real datasets obtained by fMRI, we demonstrate that the proposed RNP is generalizable across brain imaging results for different sets of video content, thus suggesting that brain imaging data can be used to robustly generate RNP for utilization as a powerful tool for estimating user preferences

Cryogenic deuterium target experiments with the GEKKO XII, green laser system

Copyright 1995 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Physics of Plasmas, 2(6), 2495-2503, 1995 and may be found at http://dx.doi.org/10.1063/1.87121

X-ray microscopy with compact pulsed sources

X-ray microscopy inherently possesses characteristics complementary to optical and electron microscopy. Short wavelength x-ray radiation, especially in the so-called, \u27water window\u27 (2.5 - 5 nm), permits a twenty-fold improvement in spatial resolution over optical microscopy while preserving a depth of field large enough (∼100 nm) to image whole biological specimens in their natural state. Whereas electron microscopy can access atomic-scale resolution, this can only be applied to biological and medical specimens at the expense of detrimental preparation procedures (staining, drying, fixing, sectioning, etc.) that preclude real-time analysis of structural changes in living organisms. We describe progress being made in an x-ray imaging technology that provides high-resolution (∼10 nm) single frame x-ray images of in-vitro specimens captured in a time sufficiently short that any radiation damage mechanisms to the structure are not recorded. Several different biology and medical research groups find this type of microscopy particularly well-suited to the detailed analysis of sub-cellular features, and to the study of live organisms subjected to various forms of external stimuli. This technology utilizes bright x-ray sources produced by compact pulse laser systems. The incorporation of advanced x-ray optical and electron-optical systems will lead to the development of a compact, real-time x-ray microscope, having a broad range of applications

High resolution X-ray micrography of live Candida albicans using laser plasma pulsed point X-ray sources

Electron microscopy is still the most frequently used method for visualization of subcellular structures in spite of limitations due to the preparation required to visualize the specimen. High resolution X-ray microscopy is a relatively new technique, still under development and restricted to a few large synchrotron X-ray sources. We utilized a single-shot laser (nanosecond) plasma to generate X-rays similar to synchrotron facilities to image live cells of Candida albicans. The emission spectrum was tuned for optimal absorption by carbon-rich material. The photoresist was then scanned by an atomic force microscope to give a differential X-ray absorption pattern. Using this technique, with a sample image time of 90 min, we have visualized a distinct 152.24 nm thick consistent ring structure around cells of C. albicans representing the cell wall, and distinct \u27craters\u27 inside, one of 570.90 nm diameter and three smaller ones, each 400 nm in diameter. This technique deserves further exploration concerning its application in the ultrastructural study of live, hydrated microbiological samples and of macromolecules

Direct Ultrastructural Imaging Of Macrophages Using A Novel X-Ray Contact Microscopy

A compact, high-resolution, laser-plasma, x-ray contact microscopy method using a table-top Nd:glass laser system has been developed. This x-ray microscopy system was applied for the observation of macrophage ultrastructures. These images were produced using proximity imaging in which a 5-ns pulse of soft x-rays with wavelengths near and inside the water windows (23å-44Å) produced by the laser-plasma were absorbed by the specimen and then registered on a photo resist. The x-ray images imprinted on the photo resist were then developed and analyzed with an atomic force microscope (AFM). Mouse thioglycollate-elicited peritoneal macrophages in suspension were examined by this new x-ray microscope. The x-ray images of the macrophages were compared with those observed by conventional transmission electron microscopy (TEM). The x-ray images showed no obvious organelles, including the nucleus and endoplasmic reticulum, as can be seen with TEM, but highland low-contrast structures caused by mass distribution of carbon were observed. Thus, using the x-ray microscopy we visualized the first x-ray images of macrophage ultrastructures. The successful x-ray imaging of macrophage ultrastructure indicates that proximity x-ray microscopy may be of value in studying physiology linked to the dynamics of a cell. Copyright © 1999 by the Society for Experimental Biology and Medicine

Water Laser Plasma X-Ray Point Source and Apparatus

A high repetition-rate laser plasma target source system and lithography system is disclosed. The target source system comprises in a preferred embodiment a liquid tank source and freezer which freezes microscopic particles into crystal shapes which are projected by a nozzle jet from a high repetition rate liquid-droplet injector into the path of a flashing laser beam, which results in producing soft x-rays of approximately 13 nm. Uncollected and unshot target crystals are collected and reliquified by a heater source in order to be recycled back to the liquid tank source. Optionally an auxiliary source and detector system can be used to allow for instantaneous triggering of the laser beam. The target source system can be incorporated into well known EUV lithography systems for the production of wafer chips

X-ray micrography and imaging of Escherichia coli cell shape using laser plasma pulsed point x-ray sources

High-resolution x-ray microscopy is a relatively new technique and is performed mostly at a few large synchrotron x-ray sources that use exposure times of seconds. We utilized a bench-top source of single-shot laser (ns) plasma to generate x-rays similar to synchrotron facilities. A 5 μl suspension of Escherichia coli ATCC 25922 in 0.9% phosphate buffered saline was placed on polymethylmethyacrylate coated photoresist, covered with a thin (100 nm) SiN window and positioned in a vacuum chamber close to the x-ray source. The emission spectrum was tuned for optimal absorption by carbon- rich material. Atomic force microscope scans provided a surface and topographical image of differential x-ray absorption corresponding to specimen properties. By using this technique we observed a distinct layer around whole cells, possibly representing the Gram-negative envelope, darker stained areas inside the cell corresponding to chromosomal DNA as seen by thin section electron microscopy, and dent(s) midway through one cell, and 1/3- and 2/3-lengths in another cell, possibly representing one or more division septa. This quick and high resolution with depth-of-field microscopy technique is unmatched to image live hydrated ultrastructure, and has much potential for application in the study of fragile biological specimens