Akihiro Enomoto

Molecular communication for nanomachines using intercellular calcium signaling

Molecular communication is engineered biological communication (e.g., cell-to-cell signaling) that allows nanomachines (e.g., engineered organisms, artificial devices) to communicate through chemical signals in an aqueous environment. This paper describes the design of a molecular communication system based on intercellular calcium signaling networks. This paper also describes possible functionalities (e.g., signal switching and aggregation) that may be achieved in such networks.

A design of a molecular communication system for nanomachines using molecular motors

Molecular communication is one solution for nano-scale communication between nanomachines. Nanomachines (e.g., biological molecules, artificial devices) represent small devices or components that perform computation, sensing, or actuation. Molecular communication provides a mechanism for one nanomachine to encode or decode information into molecules and to send information to another nanomachine. This paper describes a molecular motor communication system in terms of a high level architecture for molecular communication. We also briefly discuss current and future work in molecular communication

Anonymity and roles associated with aggressive posts in an online forum

Cyberbullying is a growing concern in online communications. Cyberbullying has negative impacts such as distress or suicide of a victim. One common type of cyberbullying attack utilizes aggressive forum posts to insult or threaten a victim. Automated tools to classify cyberbullying may aid in avoiding or reducing the negative impacts of cyberbullying. One approach to produce an automated tool is to identify features of forum posts which may be indicators of cyberbullying. One feature of a forum post is the role of the author of the forum post, such as a bully, victim, or defender. Another feature is whether the forum post insults or threatens an individual (e.g., contains insults directed at a victim). Attackers may use aggressive forum posts to attack someone and defenders may use aggressive forum posts to retaliate against attackers. Another feature is whether the communication is anonymous (e.g., sending forum posts with no identifier) since cyberbullies utilize anonymity to reduce the ability of the victim to defend themselves and to shield the cyberbully from social consequences. In this paper, forum posts were labeled in an online forum for these features. Text matching techniques had some success in identifying aggressiveness forum posts including both attacks and defends. Anonymity of forum posts (i.e., forum posts with no identifier) was identified as a criterion to distinguish attackers (more anonymous relative to non-aggressive communications) from defenders (less anonymous relative to non-aggressive communications).

Molecular Communication Technology as a Biological ICT

This chapter provides a comprehensive overview of state-of-the art research on molecular communication—a molecule-based communication paradigm for biological machines. Unlike current telecommunications based on electric or optical signals, molecular communication exploits biological molecules as information carriers. In molecular communication, senders of communication encode information onto molecules and transmit to the environment. The information coded molecules then propagate in the environment to reach receivers of communication, which capture and biochemically react to the molecules (i.e., decode the information from the information coded molecules). Since biological molecules are compatible with biological systems, molecular communication is expected to impact medical domains such as human health monitoring where implant biological machines interact with biological cells through molecular communication. This chapter describes key concepts, architecture, potential applications of molecular communication as well as existing research on engineering molecular communication components and systems.

Solar cell module colored with fluorescent plate

In order to color the solar cell module with a small decrease in energy conversion efficiency, a fluorescent plate was used as a protecting plate for the module. The effect of the coloration on the energy conversion efficiency was discussed on the basis of a simple model for the absorption and re-emission of light in the fluorescent plate and spectral reflection of the solar cell module. The measured energy conversion efficiency of the colored solar cell module was comparable to that of the non-colored module, when the fluorescent quantum efficiency was nearly equal to 1.0. The coloration of green yielded a 2.7% increase in energy conversion efficiency, and the colorations of orange, pink, and red, could be made with 0.5%, 1.5% and 5.5% decrease in energy conversion efficiency. The small increase in energy conversion efficiency was attributable to the fact that the reflectivity of the colored module was a little less than that of the non-colored module.

Measuring Distance From Single Spike Feedback Signals in Molecular Communication

Systems of bionanomachines may benefit future applications which require interaction with biological systems at the nano- to microscale. Molecular communication is a suitable communication mechanism for autonomous bionanomachines which are limited in size and capability and for interfacing with biological systems. In molecular communication, a bionanomachine transmits information to a receiver bionanomachine by modulating the concentration of molecules in the environment. One promising direction for molecular communication is for a bionanomachine to measure the distance to another bionanomachine in order to perform location-based functionality or to adapt communications using the measured distance. In this paper, a bionanomachine measures the distance to another bionanomachine by requesting the other bionanomachine to transmit a feedback signal of many molecules transmitted over a short time interval (i.e., a single spike of molecules). Upon receiving the feedback signal, the bionanomachine which requested the feedback signal then estimates distance by measuring the Round Trip Time (RTT) or Signal Attenuation (SA) of the received feedback signal. The propagation of molecules and the receiving of molecules are modeled to investigate how distance impacts measured RTT and SA. Simulations are performed to measure the accuracy of the distance measurement, the time required to measure distance, and how the number of molecules transmitted affects accuracy.

Design of self-organizing microtubule networks for molecular communication

In this paper, we investigated approaches to form a self-organizing microtubule network. Microtubules are protein filaments naturally occurring in the aqueous environment of cells. A microtubule network connects multiple nano- or micro-scale objects (i.e., nanomachines). In the paper, we propose two approaches to form an in vitro microtubule network in a self-organizing manner. The first approach utilizes polymerization and depolymerization of microtubules. The second approach utilizes molecular motors to reorganize a microtubule network. In addition, we conducted preliminary in vitro experiments to investigate the feasibility of the proposed approaches. In the preliminary experiments, we observed that a few sender and receiver nanomachines were interconnected with the first approach, and that distinct topologies of microtubules were reorganized with the second approach.

Interfacing with nanomachines through molecular communication

Molecular communication is a new paradigm for communication between biological nanomachines over a short-range (a nano- and micro-scale range). Biological nanomachines are nano- and micro-scale devices that either exist in the biological world or are artificially created from biological materials and that perform simple functions such as sensing, logic, and actuation. Molecular communication provides a mechanism for biological nanomachines to communicate information by propagating molecules that represent the information. Molecular communication is based on observations of existing biological systems which use molecules as communication carriers. With the advancement of current research in areas such as synthetic biology and bio-nanotechnologies, it may become relatively easy in the near future to develop systems of biological nanomachines communicating through molecules. In this paper, we present a framework for describing molecular communication systems.

Simulating molecular motor uni-cast information rate for molecular communication

For Workshop on Biological and Bio-Inspired Information Theory. Future applications may require communication mechanisms for nanomachines to coordinate with other nano-machines. Nanomachines are artificial or biological macromolecules that perform simple computing, sensing, or actuation. A molecular communication system is one method for communication among nanomachines: a nanomachine(s) releases molecules to represent information (sending), the information molecules propagate through the environment, and another nanomachine(s) reacts to the molecules as information (receiving). Developing advanced molecular communication systems may be simpler with generic uni-cast and broadcast mechanisms for transmission from one nanomachine to one or more nanomachines(s). All communication processes (encoding, sending, propagating, receiving, decoding) impact the design of a communication system. In this paper, we improve the design of a molecular communication system by characterizing several techniques for sending, propagating, and receiving information molecules. First, we measure the probability of receiving information molecules for three propagation techniques (diffusion-only, directional molecular motors, and a hybrid using both diffusion and motors). Next, we model bit transmission to measure signal, noise and information rate. Finally, we model techniques to modify signal and noise such as noise dissipation, sending multiple information molecules, and receiving multiple information molecules. We compare the information rates of the various techniques to identify promising approaches for uni-cast and broadcast transmission.

Molecular communication: Uni-cast communication on a microtubule topology

Molecular communication is one method for communication among nano-scale components (artificial or biological) that perform simple computation, sensing, or actuation. Future applications using nano-scale components may require communication mechanisms to coordinate with other components. For example, uni-cast is one primitive communication mechanism for transmission from one sender to one receiver and allows two nano-scale components to coordinate and perform some function. In this paper, we consider designing a molecular communication system that applies a molecular motor transport mechanism existing in biological cells. In molecular motor transport, a sender (nano-scale component) releases information molecules, and molecular motors transport the information molecules along protein filaments to a receiver (nano-scale component) up to hundreds of micrometers away. We consider a plus-centered aster (receiver with multiple protein filaments leading to the receiver) as one possible arrangement for protein filaments. We perform simulations to evaluate the probability of sending an information molecule to the receiver. The simulation results indicate that the proposed uni-cast molecular communication is limited in range (distance between sender and receiver with a reasonable success probability) and that the proposed molecular motor system transports simulated information molecules (100 nm radius spheres) with a greater success probability and than a passive diffusion-only system.