1,720,967 research outputs found
Physical Layer Security for In-Body Wireless Cardiac Sensor Network
Full text linkThe thesis explores the physical layer security approaches for securing an in body multi-nodal leadless cardiac pacemaker (LCP) communication system. Pacemakers are implanted medical devices, used to treat different types of cardiac arrhythmias. The widely used version of these pacemakers is implanted with intravascular leads. Due to lead related complications, the next generation of pacemaker systems are becoming wireless i.e., connecting multiple nodes wirelessly without intravascular leads.
Besides the unquestionable benefits of LCPs such as less invasive surgery, there are also some concerns associated with it. The wireless nature of these devices is a significant security risk and could lead to threats like eavesdropping, data tampering, and device modification.
This thesis deals with the problem of quantifying the severity of risks associated with the wireless nature of these next generation LCPs and the corresponding countermeasures by utilizing the physical layer security (PLS) techniques.
To evaluate the system eavesdropping risk without PLS, we use the concept of communication link outage probability. A link is said to be in an outage if the received signal to noise (SNR) ratio falls below the threshold required for error free decoding. We compute the eavesdropper (Eve) link outage probability for evaluation of eavesdropping risk with respect to the distance around the body. Similarly, for developing the corresponding countermeasures, we explore two different approaches of PLS for securing LCP. The first approach provides a secure communication strategy via channel modeling and offers data secrecy and reliability simultaneously, without use of data encryption. The second approach provides an alternative for symmetric key generation between legitimate nodes and avoids the use of key management and distribution servers as in the case of conventional cryptographic methods.
For channel modeling strategy, our hypothesis is on the availability of positive secrecy capacity in the close proximity of the human body. Secrecy capacity is the performance metric that supports secrecy and reliability at the same time and is the maximum attainable secure communication rate without leakage of information to Eve. Secrecy capacity depends on the inherent noise within the wireless channels.
To implement a channel modeling approach, prior knowledge about wireless channels is required and can only be implemented when the legitimate nodes have superior channel quality over Eve on the physical layer.
To evaluate the secrecy capacity, the methodology of electromagnetic simulations and experimental measurements is adopted for modeling the in-body to in-body (legitimate) and in-body to off-body (Eve) wireless channels. The results show that the positive secrecy capacity is achievable within the human personal space of 25 cm, with practical antenna realizations. Furthermore, to examine the effect of electromagnetic radiations through the human body across different angles in three dimensional space, the spatial secrecy capacity is also evaluated. The angle from which the maximum leakage of information takes place is found to the left from front, just above the heart and is termed as the “Eve sweet spot angle”. Eve’s sweet spot angle has the least secrecy capacity among all the eavesdropper spatial positions with the human heart as a reference position. The results proved our hypothesis that the human body as a lossy medium for electromagnetic propagation inherently provides high attenuation to off-body Eve link, thus offering legitimate nodes an advantage on the physical layer for implementation of channel modeling approach.
For solving the issues related to key management and distribution in case of traditional cryptographic algorithms, the dissertation also explores the source modeling approach to establish symmetric keys between legitimate nodes. The source modeling approach exploit the correlated information source between legitimate nodes for key generation. We hypothesized that the electromagnetic reflections experienced due to in-body transmissions provide enough randomness to generate a symmetric key from wireless parameters like received signal strength (RSS), phase, angle of arrival, etc. Therefore, we generated a symmetric key string between the in-body nodes by utilizing the randomness in the RSS measurements. Similarly, due to the availability of inherent physiological signals, the feasibility of symmetric group key establishment across multiple nodes of the leadless pacemaker system is also analyzed. Both methods provide viable alternatives with RSS based key generation method outperforming the other with a bit mismatch rate of approximately 1%
Physical Layer Security for In-Body Wireless Cardiac Sensor Network
No full textThe thesis explores the physical layer security approaches for securing an in body multi-nodal leadless cardiac pacemaker (LCP) communication system. Pacemakers are implanted medical devices, used to treat different types of cardiac arrhythmias. The widely used version of these pacemakers is implanted with intravascular leads. Due to lead related complications, the next generation of pacemaker systems are becoming wireless i.e., connecting multiple nodes wirelessly without intravascular leads.
Besides the unquestionable benefits of LCPs such as less invasive surgery, there are also some concerns associated with it. The wireless nature of these devices is a significant security risk and could lead to threats like eavesdropping, data tampering, and device modification.
This thesis deals with the problem of quantifying the severity of risks associated with the wireless nature of these next generation LCPs and the corresponding countermeasures by utilizing the physical layer security (PLS) techniques.
To evaluate the system eavesdropping risk without PLS, we use the concept of communication link outage probability. A link is said to be in an outage if the received signal to noise (SNR) ratio falls below the threshold required for error free decoding. We compute the eavesdropper (Eve) link outage probability for evaluation of eavesdropping risk with respect to the distance around the body. Similarly, for developing the corresponding countermeasures, we explore two different approaches of PLS for securing LCP. The first approach provides a secure communication strategy via channel modeling and offers data secrecy and reliability simultaneously, without use of data encryption. The second approach provides an alternative for symmetric key generation between legitimate nodes and avoids the use of key management and distribution servers as in the case of conventional cryptographic methods.
For channel modeling strategy, our hypothesis is on the availability of positive secrecy capacity in the close proximity of the human body. Secrecy capacity is the performance metric that supports secrecy and reliability at the same time and is the maximum attainable secure communication rate without leakage of information to Eve. Secrecy capacity depends on the inherent noise within the wireless channels.
To implement a channel modeling approach, prior knowledge about wireless channels is required and can only be implemented when the legitimate nodes have superior channel quality over Eve on the physical layer.
To evaluate the secrecy capacity, the methodology of electromagnetic simulations and experimental measurements is adopted for modeling the in-body to in-body (legitimate) and in-body to off-body (Eve) wireless channels. The results show that the positive secrecy capacity is achievable within the human personal space of 25 cm, with practical antenna realizations. Furthermore, to examine the effect of electromagnetic radiations through the human body across different angles in three dimensional space, the spatial secrecy capacity is also evaluated. The angle from which the maximum leakage of information takes place is found to the left from front, just above the heart and is termed as the “Eve sweet spot angle”. Eve’s sweet spot angle has the least secrecy capacity among all the eavesdropper spatial positions with the human heart as a reference position. The results proved our hypothesis that the human body as a lossy medium for electromagnetic propagation inherently provides high attenuation to off-body Eve link, thus offering legitimate nodes an advantage on the physical layer for implementation of channel modeling approach.
For solving the issues related to key management and distribution in case of traditional cryptographic algorithms, the dissertation also explores the source modeling approach to establish symmetric keys between legitimate nodes. The source modeling approach exploit the correlated information source between legitimate nodes for key generation. We hypothesized that the electromagnetic reflections experienced due to in-body transmissions provide enough randomness to generate a symmetric key from wireless parameters like received signal strength (RSS), phase, angle of arrival, etc. Therefore, we generated a symmetric key string between the in-body nodes by utilizing the randomness in the RSS measurements. Similarly, due to the availability of inherent physiological signals, the feasibility of symmetric group key establishment across multiple nodes of the leadless pacemaker system is also analyzed. Both methods provide viable alternatives with RSS based key generation method outperforming the other with a bit mismatch rate of approximately 1%
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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