Analysis and Ad-hoc Networking Solutions for Cooperative Relaying Systems

Users of mobile networks are increasingly demanding higher data rates from their service providers. To cater to this demand, various signal processing and networking algorithms have been proposed. Amongst them the multiple input multiple output (MIMO) scheme of wireless communications is one of the most promising options. However, due to certain physical restrictions, e.g., size, it is not possible for many devices to have multiple antennas on them. Also, most of the devices currently in use are single-antenna devices. Such devices can make use of the MIMO scheme by employing cooperative MIMO methods. This involves nearby nodes utilizing the antennas of each other to form virtual antenna arrays (VAAs). Nodes with limited communication ranges can further employ multi-hopping to be able to communicate with far away nodes. However, an ad-hoc communications scheme with cooperative MIMO multi-hopping can be challenging to implement because of its de-centralized nature and lack of a centralized controling entity such as a base-station. This thesis looks at methods to alleviate the problems faced by such networks.In the first part of this thesis, we look, analytically, at the relaying scheme under consideration and derive closed form expressions for certain performance measures (signal to noise ratio (SNR), symbol error rate (SER), bit error rate (BER), and capacity) for the co-located and cooperative multiple antenna schemes in different relaying configurations (amplify-and-forward and decode-and-forward) and different antenna configurations (single input single output (SISO), single input multiple output (SIMO) and MIMO). These expressions show the importance of reducing the number of hops in multi-hop communications to achieve a better performance. We can also see the impact of different antenna configurations and different transmit powers on the number of hops through these simplified expressions.We also look at the impact of synchronization errors on the cooperative MIMO communications scheme and derive a lower bound of the SINR and an expression for the BER in the high SNR regime. These expressions can help the network designers to ensure that the quality of service (QoS) is satisfied even in the worst-case scenarios. In the second part of the thesis we present some algorithms developed by us to help the set-up and functioning of cluster-based ad-hoc networks that employ cooperative relaying. We present a clustering algorithm that takes into account the battery status of nodes in order to ensure a longer network life-time. We also present a routing mechanism that is tailored for use in cooperative MIMO multi-hop relaying. The benefits of both schemes are shown through simulations.A method to handle data in ad-hoc networks using distributed hash tables (DHTs) is also presented. Moreover, we also present a physical layer security mechanism for multi-hop relaying. We also analyze the physical layer security mechanism for the cooperative MIMO scheme. This analysis shows that the cooperative MIMO scheme is more beneficial than co-located MIMO in terms of the information theoretic limits of the physical layer security.Nutzer mobiler Netzwerke fordern zunehmend höhere Datenraten von ihren Dienstleistern. Um diesem Bedarf gerecht zu werden, wurden verschiedene Signalverarbeitungsalgorithmen entwickelt. Dabei ist das "Multiple input multiple output" (MIMO)-Verfahren für die drahtlose Kommunikation eine der vielversprechendsten Techniken. Jedoch ist aufgrund bestimmter physikalischer Beschränkungen, wie zum Beispiel die Baugröße, die Verwendung von mehreren Antennen für viele Endgeräte nicht möglich. Dennoch können solche Ein-Antennen-Geräte durch den Einsatz kooperativer MIMO-Verfahren von den Vorteilen des MIMO-Prinzips profitieren. Dabei schließen sich naheliegende Knoten zusammen um ein sogenanntes virtuelles Antennen-Array zu bilden. Weiterhin können Knoten mit beschränktem Kommunikationsbereich durch mehrere Hops mit weiter entfernten Knoten kommunizieren. Allerdings stellt der Aufbau eines solchen Ad-hoc-Netzwerks mit kooperativen MIMO-Fähigkeiten aufgrund der dezentralen Natur und das Fehlen einer zentral-steuernden Einheit, wie einer Basisstation, eine große Herausforderung dar. Diese Arbeit befasst sich mit den Problemstellungen dieser Netzwerke und bietet verschiedene Lösungsansätze.Im ersten Teil dieser Arbeit werden analytisch in sich geschlossene Ausdrücke für ein kooperatives Relaying-System bezüglicher verschiedener Metriken, wie das Signal-Rausch-Verhältnis, die Symbolfehlerrate, die Bitfehlerrate und die Kapazität, hergeleitet. Dabei werden die "Amplify-and forward" und "Decode-and-forward" Relaying-Protokolle, sowie unterschiedliche Mehrantennen-Konfigurationen, wie "Single input single output" (SISO), "Single input multiple output" (SIMO) und MIMO betrachtet. Diese Ausdrücke zeigen die Bedeutung der Reduzierung der Hop-Anzahl in Mehr-Hop-Systemen, um eine höhere Leistung zu erzielen. Zudem werden die Auswirkungen verschiedener Antennen-Konfigurationen und Sendeleistungen auf die Anzahl der Hops analysiert.  Weiterhin wird der Einfluss von Synchronisationsfehlern auf das kooperative MIMO-Verfahren herausgestellt und daraus eine untere Grenze für das Signal-zu-Interferenz-und-Rausch-Verhältnis, sowie ein Ausdruck für die Bitfehlerrate bei hohem Signal-Rausch-Verhältnis entwickelt. Diese Zusammenhänge sollen Netzwerk-Designern helfen die Qualität des Services auch in den Worst-Case-Szenarien sicherzustellen. Im zweiten Teil der Arbeit werden einige innovative Algorithmen vorgestellt, die die Einrichtung und die Funktionsweise von Cluster-basierten Ad-hoc-Netzwerken, die kooperative Relays verwenden, erleichtern und verbessern. Darunter befinden sich ein Clustering-Algorithmus, der den Batteriestatus der Knoten berücksichtigt, um eine längere Lebensdauer des Netzwerks zu gewährleisten und ein Routing-Mechanismus, der auf den Einsatz in kooperativen MIMO Mehr-Hop-Systemen zugeschnitten ist. Die Vorteile beider Algorithmen werden durch Simulationen veranschaulicht. Eine Methode, die Daten in Ad-hoc-Netzwerken mit verteilten Hash-Tabellen behandelt wird ebenfalls vorgestellt. Darüber hinaus wird auch ein Sicherheitsmechanismus für die physikalische Schicht in Multi-Hop-Systemen und kooperativen MIMO-Systemen präsentiert. Eine Analyse zeigt, dass das kooperative MIMO-Verfahren deutliche Vorteile gegenüber dem konventionellen MIMO-Verfahren hinsichtlich der informationstheoretischen Grenzen der Sicherheit auf der physikalischen Schicht aufweist

Psychiatric Aspects of COVID-19: Depression, Anxiety and Stress - A Case Report

The novel coronavirus has had an impact on our physical and mental health, as well as enforcing dramatic changes to our daily lives. On top of this, it has become more difficult for people to find outlets to release stress because of limited outdoor and indoor activities. In these circumstances, some people begin to feel depressed and/or anxious. This article reports a case of panic attacks and anxiety caused by the stress experienced due to the pandemic

How to achieve Financial Gains with Corporate Social Responsibility in businesses

This research paper presents a conceptual framework for companies to manage their financial gains or profitability with the help of Corporate Social Responsibility initiatives and attempts. A case of Sharp electronics and Samsung will also be discussed that how these companies gain profits through implementing CSR in companies. And we will also do a graphical analysis of Asian countries involve in CSR activities. The results of the present study showed that an organization can increase its output by effectively using corporate social responsibility activities. Key words: Corporate Social Responsibility, Financial gains, Conceptual framewor

Characterizing Information Diets of Social Media Users

With the widespread adoption of social media sites like Twitter and Facebook, there has been a shift in the way information is produced and consumed. Earlier, the only producers of information were traditional news organizations, which broadcast the same carefully-edited information to all consumers over mass media channels. Whereas, now, in online social media, any user can be a producer of information, and every user selects which other users she connects to, thereby choosing the information she consumes. Moreover, the personalized recommendations that most social media sites provide also contribute towards the information consumed by individual users. In this work, we define a concept of information diet -- which is the topical distribution of a given set of information items (e.g., tweets) -- to characterize the information produced and consumed by various types of users in the popular Twitter social media. At a high level, we find that (i) popular users mostly produce very specialized diets focusing on only a few topics; in fact, news organizations (e.g., NYTimes) produce much more focused diets on social media as compared to their mass media diets, (ii) most users' consumption diets are primarily focused towards one or two topics of their interest, and (iii) the personalized recommendations provided by Twitter help to mitigate some of the topical imbalances in the users' consumption diets, by adding information on diverse topics apart from the users' primary topics of interest.Comment: In Proceeding of International AAAI Conference on Web and Social Media (ICWSM), Oxford, UK, May 201

RISK FACTORS OF HUMAN RABIES IN SOUTH ASIA: A SYSTEMATIC REVIEW

Background Rabies as a zoonotic viral disease is one of the neglected tropical diseases with high incidence among the poorest communities of least developed and developing countries of Africa and Asia. Aim This study aims to investigate the risk factors of human rabies in south Asia, with focus on Bangladesh, India and Pakistan. Method A systematic review approach was adopted, which included studies that identified the risk factors of human rabies in the three south Asian countries from 2007 to 2016. Electronic databases searched include PsycINFO, PubMed Central [PMC] and Cumulative Index of Nursing and Allied Health Literature [CINAHL]. Appropriate data screening was carried out to extract relevant articles. Finally, the articles were quality appraised and synthesized with a narrative synthesis approach. Result Eight relevant studies were finally identified, with either moderate or high quality. The studies identified one or more risk factors of human rabies. The findings include; animal bite mostly from certain stray animals (dog, cat, monkey and rat). Secondly, poor knowledge/awareness of the people about human rabies, thus people were ignorant of the need to seek for immediate treatment following animal bites. Thirdly, poor traditional/cultural practices following bites from infected animals. Fourthly, socioeconomic factors and finally, poor use of preventive measures against rabies. Conclusion Based on the findings, it is concluded that most of the factors predisposing to rabies infection in south Asia are preventable, hence; Government authorities, non-governmental organizations and philanthropists should be more committed toward increasing awareness about the consequences of the infection as well as providing free and accessible treatments across each country. Keywords: risk, factors, rabies, Bangladesh, India, Pakista

Discrimination in Algorithmic Decision Making: From Principles to Measures and Mechanisms

The rise of algorithmic decision making in a variety of applications has also raised concerns about its potential for discrimination against certain social groups. However, incorporating nondiscrimination goals into the design of algorithmic decision making systems (or, classifiers) has proven to be quite challenging. These challenges arise mainly due to the computational complexities involved in the process, and the inadequacy of existing measures to computationally capture discrimination in various situations. The goal of this thesis is to tackle these problems. First, with the aim of incorporating existing measures of discrimination (namely, disparate treatment and disparate impact) into the design of well-known classifiers, we introduce a mechanism of decision boundary covariance, that can be included in the formulation of any convex boundary-based classifier in the form of convex constraints. Second, we propose alternative measures of discrimination. Our first proposed measure, disparate mistreatment, is useful in situations when unbiased ground truth training data is available. The other two measures, preferred treatment and preferred impact, are useful in situations when feature and class distributions of different social groups are significantly different, and can additionally help reduce the cost of nondiscrimination (as compared to the existing measures). We also design mechanisms to incorporate these new measures into the design of convex boundary-based classifiers.Die Vielzahl der Anwendungen, die Algorithmen immer stärker an Entscheidungsprozessen beteiligen, wächst stetig. Dadurch werden Bedenken über die potenzielle Diskriminierung bestimmter gesellschaftlicher Gruppen aufgeworfen. Die Aufnahme von Nichtdiskriminierungszielsetzungen bei der Gestaltung algorithmischer Entscheidungs- bzw. Klassifizierungssysteme hat sich jedoch als grosse Herausforderung herausgestellt. Zum einen sind die nötigen Berechnungen komplex und zum anderen sind die existierenden Metriken unzureichend, um Diskriminierung in bestimmten Situationen rechnerisch zu erfassen. Das Ziel dieser Arbeit ist es, diese Problematik anzugehen. Als erstes stellen wir einen Decision Boundary-basierten Kovarianzmechanismus vor, der genutzt werden kann, um existierende Diskriminierungsmetriken (also Disparate Treatment und Disparate Impact) beim Entwurf von gängigen Klassifizierungsalgorithmen einzusetzen. Der Ansatz kann für jeden konvexen Boundary-basierten Klassifizierungsalgorithmus in Form konvexer Constraints formuliert werden. Als nächstes definieren wir neue Diskriminierungsmetriken. Unsere erste Metrik namens Disparate Mistreatment kommt in Situationen zum Einsatz, in denen die Referenzdaten nicht zugunsten einer sozialen Gruppe verzerrt sind. Die übrigen beiden Metriken namens Preferred Treatment und Preferred Impact sind für Situationen konzipiert, in denen die Feature- und Klassenverteilungen unterschiedlicher sozialer Gruppen stark voneinander abweichen. Sie können dabei helfen, die Kosten von Nichtdiskriminierung im Vergleich zu bestehenden Metriken zu reduzieren. Wir zeigen ebenfalls, wie diese neuen Metriken in konvexen Boundary-basierten Klassifizierungsalgorithmen genutzt werden können

Reservoir Characterization and Modelling with Diagenetic Trends of carbonates of the Kawagarh Formation: A Section exposed in the Kala-Chitta Range, Pakistan

Present study is focused on the diagenetic studies and reservoir characterization of the Cretaceous KawagarhFormation exposed in the Gandab village, Kala-Chitta range, north-western Himalayan Fold-and-Thrust belt, Pakistan.The formation is composed of argillaceous limestone and dark grey marls. A total of thirty-three representativecarbonate rock samples were collected at equal intervals of three meters. Various diagenetic features includingcementation, micritization, pyrite precipitation, neomorphism, fracturing, sparitization and stylolitization were observedin the studied rocks which occur in the marine, meteoric and deep burial diagenetic environments respectively. Suchdiagenetic features control the reservoir quality of the rock unit. Porosity types include mostly vuggy and fracture,while minor stylolitic porosity were noted with quantity ranging from 2.66% to 3.88%. The carbonates of KawagarhFormation are highly fractured, but the filling of these fractures due to precipitation of calcite or micritic mud hasgreatly reduced its reservoir potential, while some unfilled fractures, stylolites and vuggs are the dominant factors thatenhance the reservoir potentiality of the Kawagarh Formation. However, the porosity values still do not mark the levelof reservoir rock. These diagenetic studies revealed very less chances for hydrocarbon accumulation as no significantporosity values have been observed and overall reservoir potential is characterized as poor

Moderating Role of Country Governance in the Relationship between Technological Innovation and Inward Foreign Direct Investment

Due to the significance of Foreign Direct Investment (FDI) in economic development, a growing body of literature aims to analyze its determinants. In this regard, this study examines the role of technological innovation in attracting FDI and explains how country governance affects thisrelationship. For empirical analysis, we analyzed panel data from a wide range of developed and emerging economies for a period of 24 years, stretching from 1993 to 2016. We used the random effect model to obtain results after applying the Hausman test. We examined the relationshipbetween technological innovation, governance (by investigating governance indicators individually), FDI and how governance moderates the relationship between technological innovation and FDI in emerging and developed economies. The findings indicated that technological innovationin the host country is important for attracting inward FDI, regardless of the recipient country’s developmental level. For developed economies, political stability showed a strengthening effect on inward FDI. However, for both emerging and developed economies, all the other governance indicators weakened the technological innovation and FDI nexus

Characterization of Diazotrophs associated with roots of Leptochloa fusca (L) Kunth

A group of nine diazotrophs were isolated from the rhizosphere of kallar grass and cultured on nitrogent-jree medium. K 5 , Ks' K9' KlD' Kl2, K13 showed high nitrogenase activity (> 18 n mol C#4 h-I viatl) whereas in K7 and K14 it was comparatively low « 5n mol C#4 h l viatl ). Maximum nitrogenase activity was found in young cultures (after 24 hours of incubation) except for K9 and Kl3 where it was maximum after 36 and 48 h, respectively. All strains were Gram-negat, produced smooth colonies and pellicles on semi-solid media. Cells of K5, K7' KID' KlI, Kl2 and K14 were pleiomorphic: Ks formed long fine rods; K9 was small, round or oval shaped; while KI4 formed beaded rods. Only Ks' K 13 and KI4were found to be motile. All isolates were able to reduce nitrate, and were positive for oxidase an catalese. None of them could denitrify or had urease activity except for K14 which was urease positive. Ks' Kl3 and KI4 were fermentative and produced red pigments. The isolates K5, KIO and KI2 are assigned to the genus Azotobacter while others remained unidentified

Radiographic evaluation of the margins of clinically acceptable metal-ceramic crowns

Objective: To radiographically evaluate the proximal marginal fit of the clinically acceptable metal-ceramic crowns. Methods: The prospective study was conducted at the dental clinics of Aga Khan University, Karachi, from July to December 2018, and comprised metal-ceramic crowns that were evaluated prior to the cementation. Clinical examinations were conducted by seating the crown on the tooth preparation and visual assessment was done using sharp explorer along the margins. Clinically acceptable crowns were then evaluated on the bite-wing radiograph. Any horizontal or vertical inaccuracy of \u3e0.5mm at the proximal margins was recorded as \u27discrepancy\u27. Data was analysed using SPSS 22. Results: Of the 230 interproximal margins of 115 crowns evaluated, 113(49.1%) sites had marginal discrepancies; 44(19.1%) horizontal discrepancies, 58(25.2%) vertical discrepancies, and 11(4.8%) having both horizontal and vertical discrepancies. Horizontal crown margin discrepancies were most associated with the mesial site of the maxillary crowns, while vertical discrepancies were commonly associated with the distal aspect of all crowns (p\u3c0.050). Conclusions: Almost half of the crowns that were considered clinically acceptable had some vertical or horizontal marginal discrepancy on radiographic evaluation