Nano/Bio-Receiver Architectures and Detection Methods for Molecular Communications

Internet of Nano Things (IoNT) is an emerging technology, which aims at extending the connectivity into nanoscale and biological environments with collaborative networks of artificial nanomachines and biological entities integrated into the Internet. To enable the IoNT and its groundbreaking applications, such as real-time intrabody health monitoring, it is imperative to devise nanoscale communication techniques with low-complexity transceiver architectures. Bio-inspired molecular communications (MC), which uses molecules to transfer information, is the most promising technique to realise IoNT due to its inherent biocompatibility and reliability in physiologically-relevant environments. Despite the substantial body of work concerning MC, the implications of an interface between MC channel and practical MC transceiver architectures are largely neglected, leading to a major gap between theory and practice. As the first step to remove this discrepancy, in this thesis, I develop a realistic analytical ICT model for microfluidic MC with surface-based receivers as a convection-diffusion-reaction system. In the second part, I focus on biological MC receivers, which can be implemented in living cells using synthetic biology tools. In this direction, I theoretically develop low-complexity and reliable MC detection methods exploiting the various statistics of the stochastic ligand-receptor interactions at the membrane of biological MC receivers. The estimation and detection theoretical analysis of these detection methods demonstrate that even single type of receptors can provide sufficient statistics to overcome the receptor saturation problem, cope with the interference of non-cognate molecules, and simultaneously sense the concentration of multiple types of ligands. I also propose synthetic receptor designs for the transduction of decision statistics into a representation by concentration of intracellular molecules, and design chemical reaction networks performing decoding with intracellular reactions. Finally, I fabricate a micro/nanoscale MC receiver based on graphene field-effect transistor biosensors and perform its ICT characterisation in a custom-designed microfluidic MC system with the information encoded into the concentration of DNAs. This experimental platform is the first practical demonstration of micro/nanoscale MC, and can serve as a testbed for developing realistic MC methods

EVALUATION OF EFFECTIVENESS OF VITAMIN TEACHER PORTAL

Distance education systems have been developing rapidly in the field of education. Since the beginning of FATIH (Opportunities to Increase and Technology to Improve Motion) Project applications, educational softwares and the concept of e-learning have been important concerns. Besides the lack or insufficiency of softwares for tablets or smart boards, the education content websites which already exist have been struggling to take part in this field. As a result, it is inevitable that there has been a competition between government supported applications and private sector. Vitamin Teacher Portal is an application that serves as a teacher training program. It is a distance education website designed for teachers to improve their both personal and professional skills. It includes live courses, forum, shares, teachers’ resources and educational videos. It is a synchronous application with Vitamin Education website which is designed for students.In this study, qualitative research method has been used. It is conducted with teachers who use Vitamin Teacher Portal to have valid results. The aim of this study is to work out the sufficiency level of this application from the point of view of teachers. By this means, it could be work out whether it is sufficient enough to meet the needs of teachers or not. We also to find out how effectively teachers, what they acquired from the portal in class

EVALUATION OF EFFECTIVENESS OF VITAMIN TEACHER PORTAL

Distance education systems have been developing rapidly in the field of education. Since the beginning of FATIH (Opportunities to Increase and Technology to Improve Motion) Project applications, educational softwares and the concept of e-learning have been important concerns. Besides the lack or insufficiency of softwares for tablets or smart boards, the education content websites which already exist have been struggling to take part in this field. As a result, it is inevitable that there has been a competition between government supported applications and private sector. Vitamin Teacher Portal is an application that serves as a teacher training program. It is a distance education website designed for teachers to improve their both personal and professional skills. It includes live courses, forum, shares, teachers’ resources and educational videos. It is a synchronous application with Vitamin Education website which is designed for students.In this study, qualitative research method has been used. It is conducted with teachers who use Vitamin Teacher Portal to have valid results. The aim of this study is to work out the sufficiency level of this application from the point of view of teachers. By this means, it could be work out whether it is sufficient enough to meet the needs of teachers or not. We also to find out how effectively teachers, what they acquired from the portal in class

Frequency-Domain Model of Microfluidic Molecular Communication Channels with Graphene BioFET-based Receivers

Molecular Communication (MC) is a bio-inspired communication paradigm utilizing molecules for information transfer. Research on this unconventional communication technique has recently started to transition from theoretical investigations to practical testbed implementations, primarily harnessing microfluidics and sensor technologies. Developing accurate models for input-output relationships on these platforms, which mirror real-world scenarios, is crucial for assessing modulation and detection techniques, devising optimized MC methods, and understanding the impact of physical parameters on performance. In this study, we consider a practical microfluidic MC system equipped with a graphene field effect transistor biosensor (bioFET)-based MC receiver as the model system, and develop an analytical end-to-end frequency-domain model. The model provides practical insights into the dispersion and distortion of received signals, thus potentially informing the design of new frequency-domain MC techniques, such as modulation and detection methods. The accuracy of the developed model is verified through particle-based spatial stochastic simulations of pulse transmission in microfluidic channels and ligand-receptor binding reactions on the receiver surface

Modeling convection-diffusion-reaction systems for microfluidic molecular communications with surface-based receivers in Internet of Bio-Nano Things.

We consider a microfluidic molecular communication (MC) system, where the concentration-encoded molecular messages are transported via fluid flow-induced convection and diffusion, and detected by a surface-based MC receiver with ligand receptors placed at the bottom of the microfluidic channel. The overall system is a convection-diffusion-reaction system that can only be solved by numerical methods, e.g., finite element analysis (FEA). However, analytical models are key for the information and communication technology (ICT), as they enable an optimisation framework to develop advanced communication techniques, such as optimum detection methods and reliable transmission schemes. In this direction, we develop an analytical model to approximate the expected time course of bound receptor concentration, i.e., the received signal used to decode the transmitted messages. The model obviates the need for computationally expensive numerical methods by capturing the nonlinearities caused by laminar flow resulting in parabolic velocity profile, and finite number of ligand receptors leading to receiver saturation. The model also captures the effects of reactive surface depletion layer resulting from the mass transport limitations and moving reaction boundary originated from the passage of finite-duration molecular concentration pulse over the receiver surface. Based on the proposed model, we derive closed form analytical expressions that approximate the received pulse width, pulse delay and pulse amplitude, which can be used to optimize the system from an ICT perspective. We evaluate the accuracy of the proposed model by comparing model-based analytical results to the numerical results obtained by solving the exact system model with COMSOL Multiphysics

Maximum Likelihood Detection With Ligand Receptors for Diffusion-Based Molecular Communications in Internet of Bio-Nano Things.

Molecular Communication (MC) is a bio-inspired communication technique that uses molecules as a method of information transfer among nanoscale devices. MC receiver is an essential component having profound impact on the communication system performance. However, the interaction of the receiver with information bearing molecules has been usually oversimplified in modeling the reception process and developing signal detection techniques. In this paper, we focus on the signal detection problem of MC receivers employing receptor molecules to infer the transmitted messages encoded into the concentration of molecules, i.e., ligands. Exploiting the observable characteristics of ligand-receptor binding reaction, we first introduce a Maximum Likelihood (ML) detection method based on instantaneous receptor occupation ratio, as aligned with the current MC literature. Then, we propose a novel ML detection technique, which exploits the amount of time the receptors stay unbound in an observation time window. A comprehensive analysis is carried out to compare the performance of the detectors in terms of bit error probability. In evaluating the detection performance, emphasis is given to the receptor saturation problem resulting from the accumulation of messenger molecules at the receiver as a consequence of intersymbol interference. The results reveal that detection based on receptor unbound time is quite reliable even in saturation, whereas the reliability of detection based on receptor occupation ratio substantially decreases as the receiver gets saturated. Finally, we also discuss the potential methods of implementing the detectors

Analyzing Factors Affecting Repurchase Intention During Gezi Park Brand Protests

During the Gezi Park protests, some major brands were criticized within social media either for what they did or did not and social pressure to boycott those brands was highly apparent. Many newspaper articles highlighted that negative WOM during the protests might have affected consumers’ brand related knowledge. This notion is further supported by previous research. What happened during and after Gezi Park protests creates a perfect environment to analyze this effect. In addition, it was believed that only a portion of the consumers were highly affected by the protest calls. Consequently, this study aims to understand whether consumers have really changed their intention to buy from of a bank and a domestic coffee chain due to protest calls. The study also analyzes whether only a proportion of the consumers were affected and whether their trust, loyalty, awareness, perceived quality, and self-construal, and the company’s perceived social responsibility played a significant role in this change. A hierarchical logistic regression procedure (Forward Wald) with 357 usable cases was used with likelihood of change in purchase as the dependent variable. The results indicate that for the domestic coffee shop only perceived social responsibility plays a role in the change of consumers’ purchase intention. However, for the bank within the study, perceived social responsibility is found to be an insignificant contributor, whereas loyalty and awareness are found   to be significant contributors to consumers’ purchase decisions. Perceived quality/trust and consumers’ self-construal are found to have no effect on the change of consumers’ intention for both brands under study. Keywords: Brand Communication, Boycott, Brand Loyalty, Purchase Intentio