2,128 research outputs found

    In the name of status:Adolescent harmful social behavior as strategic self-regulation

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    Adolescent harmful social behavior is behavior that benefits the person that exhibits it but could harm (the interest of) another. The traditional perspective on adolescent harmful social behavior is that it is what happens when something goes wrong in the developmental process, classifying such behaviors as a self-regulation failure. Yet, theories drawing from evolution theory underscore the adaptiveness of harmful social behavior and argue that such behavior is enacted as a means to gain important resources for survival and reproduction; gaining a position of power This dissertation aims to examine whether adolescent harmful social behavior can indeed be strategic self-regulation, and formulated two questions: Can adolescent harmful social behavior be seen as strategic attempts to obtain social status? And how can we incorporate this status-pursuit perspective more into current interventions that aim to reduce harmful social behavior? To answer these questions, I conducted a meta-review, a meta-analysis, two experimental studies, and an individual participant data meta-analysis (IPDMA). Meta-review findings of this dissertation underscore that when engaging in particular behavior leads to the acquisition of important peer-status-related goals, harmful social behavior may also develop from adequate self-regulation. Empirical findings indicate that the prospect of status affordances can motivate adolescents to engage in harmful social behavior and that descriptive and injunctive peer norms can convey such status prospects effectively. IPDMA findings illustrate that we can reach more adolescent cooperation and collectivism than we are currently promoting via interventions. In this dissertation, I argue we can do this in two ways. One, teach adolescents how they can achieve status by behaving prosocially. And two, change peer norms that reward harmful social behavior with popularity

    Rules, frequency, and predictability in morphological generalization: behavioral and computational evidence from the German plural system

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    Morphological generalization, or the task of mapping an unknown word (such as a novel noun Raun) to an inflected form (such as the plural Rauns), has historically proven a contested topic within computational linguistics and cognitive science, e.g. within the past tense debate (Rumelhart and McClelland, 1986; Pinker and Prince, 1988; Seidenberg and Plaut, 2014). Marcus et al. (1995) identified German plural inflection as a key challenge domain to evaluate two competing accounts of morphological generalization: a rule generation view focused on linguistic features of input words, and a type frequency view focused on the distribution of output inflected forms, thought to reflect more domain-general cognitive processes. More recent behavioral and computational research developments support a new view based on predictability, which integrates both input and output distributions. My research uses these methodological innovations to revisit a core dispute of the past tense debate: how do German speakers generalize plural inflection, and can computational learners generalize similarly? This dissertation evaluates the rule generation, type frequency, and predictability accounts of morphological generalization in a series of behavioral and computational experiments with the stimuli developed by Marcus et al.. I assess predictions for three aspects of German plural generalization: distribution of infrequent plural classes, influence of grammatical gender, and within-item variability. Overall, I find that speaker behavior is best characterized as frequency-matching to a phonologically-conditioned lexical distribution. This result does not support the rule generation view, and qualifies the predictability view: speakers use some, but not all available information to reduce uncertainty in morphological generalization. Neural and symbolic model predictions are typically overconfident relative to speakers; simple Bayesian models show somewhat higher speaker-like variability and accuracy. All computational models are outperformed by a static phonologically-conditioned lexical baseline, suggesting these models have not learned the selective feature preferences that inform speaker generalization

    Temporal cascade model for analyzing spread in evolving networks

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    Current approaches for modeling propagation in networks (e.g., of diseases, computer viruses, rumors) cannot adequately capture temporal properties such as order/duration of evolving connections or dynamic likelihoods of propagation along connections. Temporal models on evolving networks are crucial in applications that need to analyze dynamic spread. For example, a disease spreading virus has varying transmissibility based on interactions between individuals occurring with different frequency, proximity, and venue population density. Similarly, propagation of information having a limited active period, such as rumors, depends on the temporal dynamics of social interactions. To capture such behaviors, we first develop the Temporal Independent Cascade (T-IC) model with a spread function that efficiently utilizes a hypergraph-based sampling strategy and dynamic propagation probabilities. We prove this function to be submodular, with guarantees of approximation quality. This enables scalable analysis on highly granular temporal networks where other models struggle, such as when the spread across connections exhibits arbitrary temporally evolving patterns. We then introduce the notion of ‘reverse spread’ using the proposed T-IC processes, and develop novel solutions to identify both sentinel/detector nodes and highly susceptible nodes. Extensive analysis on real-world datasets shows that the proposed approach significantly outperforms the alternatives in modeling both if and how spread occurs, by considering evolving network topology alongside granular contact/interaction information. Our approach has numerous applications, such as virus/rumor/influence tracking. Utilizing T-IC, we explore vital challenges of monitoring the impact of various intervention strategies over real spatio-temporal contact networks where we show our approach to be highly effective

    Constructing a profile for proactive career self-management in public higher education institutions in Ghana

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    Text in English with abstracts and keywords in English, isiXhosa, and isiZuluThe principal focus of this research study was to investigate the relationship among psychosocial career pre-occupation, social connectedness, and organisational commitment, and to determine whether an overall proactive career management profile can be constructed to inform career self-management practices in public higher education institutions (HEIs) in Ghana. Again, the research study intended to provide a background for testing hypotheses and theories as well as moderating the effect of socio-demographic characteristics (age, gender, marital status and job level) on the relationship between psychosocial career pre-occupations, social connectedness and organisational commitment. A cross-sectional quantitative approach was conducted on a purposively selected sample of senior staff comprising academic and administrative staff (n = 288), from a single public higher educational institution in Ghana. The measuring instruments include a career pre-occupations inventory workplace friendship scale and an organisational commitment scale. Descriptive statistics (mean, standard deviation, skewness and kurtosis), bi-variate correlation analysis (Pearson product moment correlation coefficient), and inferential and multivariate statistics (SEM analysis, moderated regression analysis, ANOVAs and independent sample t-test) were used for the study. Descriptive, bi-variate correlation and inferential statistics revealed that individual psychosocial career pre-occupations, social connectedness and organisational commitment can be used as elements within a proactive career self-management framework within the Ghanaian higher education institutions. The results of the moderated analysis showed that respondents’ gender and job level moderated employees’ level of psychosocial career pre-occupations in predicting organisational commitment. Furthermore, the test for significant mean differences revealed that gender, marital status and job level differed marginally in their psychosocial career pre-occupations, social connectedness and commitment to the organisation. Theoretically and empirically, the results advanced the career construction theory by empirically validating the core elements of career self-management. Practically, a recommendation was made to inform human resource (HR) managers and HR practitioners in public higher education institutions in Ghana and the consequences indicated in the study offer the opportunity to monitor and provide strategies and interventions for employees in their quest for career choices.Ugqaliselo oluphambili kolu phononongo lophando yayikukuphanda ubudlelwane phakathi komsebenzi wangaphambi kwekhondo ngokwesimo sengqondo nangokwezentlalo (psychosocial career pre-occupation), ukuziphatha, nokunxulumana kwezinto zokuziphatha nezentlalo (social connectedness), kunye nokuzibophelela kulungelelaniso /kucwangciso lombutho (organisational commitment), nokuqonda ukuba ingaba iprofayili yeendlela zokulawula ikhondo elisebenzayo elipheleleyo inokwakhelwa ukwazisa izenzo zekhondo lomsebenzi lokuzilawula kumaziko emfundo ephakamileyo karhulumente/oluntu (HEIs) eGhana. Kwakhona , uphononongo lophando lwaluzimisele ukunikezela ngomhlaba osisiseko wokuvavanya ingcinga ethathwa njengeyinyaniso engekaqinisekiswa (hypothesis) neethiyori kwakunye nokumodereyitha impembelelo yeempawu zedemografi yoluntu, i-socio-demographic characteristics (iminyaka, isini, imeko yomtshato,kunye nenqanaba lomsebenzi) kubudlelwane phakathi kwemisebenzi yangaphambi kwekhondo nemeko yezengqondo nabantu (psychosocial career pre-occupations), unxulumano lwabantu kunye nokuzibophelela kumbutho (organizational commitment). Inkqubo yophando ngokobungakanani enqamlezileyo ngokwamacandelo ahlukeneyo (cross sectional quantitative approach) yenziwe kwisampulu ekhethwe ngenjongo kujoliswe kubasebenzi abaphezulu/abadala ababandakanya izifundiswa nabasebenzi bezolawulo (n = 288), besuka kwiziko elinye loluntu lemfundo ephakamileyo eGhana. Izixhobo zokulinganisa zibandakanya uluhlu lwezinto kwisikali semisebenzi yangaphambi kwekhondo ubudlelwane kunye nokuzibophelela kumbutho kwindawo yokusebenzela. Iinkcukacha-manani ezichazayo (i-avareji, ukutenxa kumgangatho (standard deviation), ubugoso (skewness) kunye nomlinganiselo weenkcukacha-manani osetyenziselwa ukuchaza ukuhanjiswa kwedatha ephawulweyo malunga nentsingiselo (kurtosis), uhlalutyo lolungelelwaniso oluphindwe kabini kunye neenkcukacha-manani ezinokuthelelelekwa (i- Pearson product moment correlation coefficient), kunye neenkcukacha manani ezizintlobo-ntlobo ezininzi ezinokuthelekelelwa (uhlalutyo lwe-SEM, uhlalutyo oluhlehlayo olonganyelweyo/ olumodareyithiweyo, i-ANOVA kunye novavanyo oluzimeleyo lwe-t-test) zasetyenziswa kolu phando/phononongo. Inkcukacha-manani ezichazayo, ulungelelwaniso/unxulumaniso oluphindwe kabini kunye nezinokuthelekelelwa ezinentsingiselo zibonise ukuba imisebenzi yangaphambi kwekhondo,ngokwemeko yengqondo neyentlalo, unxulumano lwentlalo yoluntu kunye nokuzibophelela kumbutho kunokusetyenziswa njengezinto ezingaphakathi kwesakhelo solawulo esisebenzayo ngaphakathi kumaziko emfundo ephakamileyo yaseGhana.Iziphumo zohlalutyo olumodareyithiweyo zibonise ukuba isini sabaphenduli nenqanaba lomsebenzi samodareyitha inqanaba labasebenzi kwimisebenzi yangaphambi kwekhondo kwimeko yengqondo nezentlolontle ekuqikeleleni ukuzibophelela kumbutho. Ngaphaya koko, uvavanyo olubalulekileyo lweeyantlukwano lubonise ukuba isini, meko yomtshato kunye nenqanaba lomsebenzi lahlukile kancinci ngokwe-avareji kwimisebenzi yaphambi kwekhondo labo yengqondo nentlalontle, unxibelelwano lwentlalo kunye nokuzinikela embuthweni. Ngokwethiyori nangobungqina, iziphumo ziqhubele phambili ithiyori yolwakhiwo lwekhondo lomsebenzi ngokuqinisekisa ngobuchule izinto ezingundoqo zokuzilawula kwekhondo lomsebenzi.Ngokwenene, kwenziwa isindululo sokwazisa abaphathi bezabasebenzi neengcali ze-HR kumaziko emfundo ephakamileyo yoluntu eGhana kwaye iziphumo ezibonakaliswe kuphononongo zinika ithuba lokubeka esweni nokubonelela ngezicwangciso-qhinga nongenelelo ngoncedo kubaqeshwa kwiphulo labo lokukhetha amakhondo omsebenzi.Lesi sifundo socwaningo sasigxile kakhulu ekuphenyeni ngobudlelwano phakathi kokucabanga ngomkhakha womsebenzi komuntu, ukuxhumana nabantu, ukuzibophezela komuntu emsebenzini, kanye nokunquma ukuthi iphrofayili yokukwazi ukuzilawula ngokuzenzela ekukhetheni umkhakha womsebenzi kungahlelwa yini ngendlela yokuthi kudlale indima ekuzilawuleleni maqondana nomkhakha womsebenzi ezikhungweni zezemfundo ephakeme zomphakathi (ama-HEI) eGhana. Kanti futhi, isifundo socwaningo sihlose ukunikeza umlando maqondana nokuhlola imicabango kanye nemibono yezinjulalwazi kanjalo nokulinganisa umphumela wezici zokuhleleka kwabantu emphakathini (iminyaka yobudala, ubulili, isimo somshado kanye nezinga lomsebenzi) ebudlelwaneni phakathi kokucabanga ngomkhakha womsebenzi komuntu, ukuxhumana nabantu, kanye nokuzibophezela emsebenzini. Kwalandelwa indlela yokubheka isibalo samaqoqo abantu emphakathini ngokukhetha ngokuqaphela isampula labasebenzi abasezikhundleni eziphezulu elibandakanya abasebenza ngezemfundo kanye nezokuphatha (n = 288), esikhungweni sezemfundo ephakeme somphakathi esisodwa eGhana. Amathuluzi okukala afaka kuwo isilinganiso sobungane basemsebenzini ekukhetheni ezinhlobeni zemikhakha ecatshangwayo kanye nesilinganiso maqondana nokuzibophezela kwabantu emsebenzini. Kulolu cwaningo kwasetshenziswa izibalo ezichazayo (okujwayelekile, ukuphambuka okuvamile, ukungalingani kanye nobukhali), ukuhlaziywa kokuhlobana okukhona phakathi kwezinombolo ezimbili (isilinganiso sokuxhumana kwezinombolo ezimbili ngokukaPearson), kanye nezibalo eziveza izimbangela nezibalo ezahlukahlukene (ukuhlaziywa kwe-SEM, ukuhlaziywa kokubuyelamuva okulingene, ama-ANOVA kanye nesampula elizimele lokuhlola). Izibalo ezichazayo, eziveza ukuhlobana phakathi kwezinombolo ezimbili kanye nezibalo eziveza izimbangela ziveze ukuthi ukucabanga ngomkhakha womsebenzi komuntu ngamunye, ukuxhumana nabantu nokuzibophezela emsebenzini kungasetshenziswa njengezinto ezikhona ohlakeni lokukwazi ukuzilawula ngokuzenzela ekukhetheni umkhakha ezikhungweni zezemfundo ephakeme zaseGhana. Imiphumela yokuhlaziywa okulingene yakhombisa ukuthi ubulili bababambiqhaza kanye nezinga labo ngokwezikhundla zomsebenzi kuhambisana nezinga abasebenzi abacabanga ngalo nomkhakha womsebenzi ekuqageleni indlela abazozibophezela ngayo emsebenzini. Ngaphezu kwalokho, ukuhlolwa komehluko omkhulu ojwayelekile kwaveza ukuthi ubulili, isimo somshado kanye nezinga ngokwesikhundla somsebenzi kwahluka kakhulu nendlela abacabanga ngayo ngomkhakha womsebenzi, ukuxhumana nabantu nokuzibophezela emsebenzini. Ngokombono wenjulalwazi nocwaningo olufakazelwe, imiphumela ithuthukise umbono wenjulalwazi wokuhlela umkhakha womsebenzi okuqinisekiswe ngokocwaningo olufakazelwe izinto ezinqala zokuzilawulela umkhakha womsebenzi. Ekusebenzeni, kwenziwa izincomo zokufundisa abaphathi babasebenzi (ba-HR) kanye nabasebenza ngezabasebenzi (ngezakwa-HR) ezikhungweni zezemfundo ephakeme zomphakathi eGhana, kanti nemiphumela evezwe ocwaningweni inikeza ithuba lokuqapha nokuhlinzeka amasu kanye nokungenelela kwabasebenzi ekwenzeni kwabo izinqumo zomsebenzi.Business ManagementPh. D. (Business Management

    Design and Real-World Evaluation of Dependable Wireless Cyber-Physical Systems

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    The ongoing effort for an efficient, sustainable, and automated interaction between humans, machines, and our environment will make cyber-physical systems (CPS) an integral part of the industry and our daily lives. At their core, CPS integrate computing elements, communication networks, and physical processes that are monitored and controlled through sensors and actuators. New and innovative applications become possible by extending or replacing static and expensive cable-based communication infrastructures with wireless technology. The flexibility of wireless CPS is a key enabler for many envisioned scenarios, such as intelligent factories, smart farming, personalized healthcare systems, autonomous search and rescue, and smart cities. High dependability, efficiency, and adaptivity requirements complement the demand for wireless and low-cost solutions in such applications. For instance, industrial and medical systems should work reliably and predictably with performance guarantees, even if parts of the system fail. Because emerging CPS will feature mobile and battery-driven devices that can execute various tasks, the systems must also quickly adapt to frequently changing conditions. Moreover, as applications become ever more sophisticated, featuring compact embedded devices that are deployed densely and at scale, efficient designs are indispensable to achieve desired operational lifetimes and satisfy high bandwidth demands. Meeting these partly conflicting requirements, however, is challenging due to imperfections of wireless communication and resource constraints along several dimensions, for example, computing, memory, and power constraints of the devices. More precisely, frequent and correlated message losses paired with very limited bandwidth and varying delays for the message exchange significantly complicate the control design. In addition, since communication ranges are limited, messages must be relayed over multiple hops to cover larger distances, such as an entire factory. Although the resulting mesh networks are more robust against interference, efficient communication is a major challenge as wireless imperfections get amplified, and significant coordination effort is needed, especially if the networks are dynamic. CPS combine various research disciplines, which are often investigated in isolation, ignoring their complex interaction. However, to address this interaction and build trust in the proposed solutions, evaluating CPS using real physical systems and wireless networks paired with formal guarantees of a system’s end-to-end behavior is necessary. Existing works that take this step can only satisfy a few of the abovementioned requirements. Most notably, multi-hop communication has only been used to control slow physical processes while providing no guarantees. One of the reasons is that the current communication protocols are not suited for dynamic multi-hop networks. This thesis closes the gap between existing works and the diverse needs of emerging wireless CPS. The contributions address different research directions and are split into two parts. In the first part, we specifically address the shortcomings of existing communication protocols and make the following contributions to provide a solid networking foundation: • We present Mixer, a communication primitive for the reliable many-to-all message exchange in dynamic wireless multi-hop networks. Mixer runs on resource-constrained low-power embedded devices and combines synchronous transmissions and network coding for a highly scalable and topology-agnostic message exchange. As a result, it supports mobile nodes and can serve any possible traffic patterns, for example, to efficiently realize distributed control, as required by emerging CPS applications. • We present Butler, a lightweight and distributed synchronization mechanism with formally guaranteed correctness properties to improve the dependability of synchronous transmissions-based protocols. These protocols require precise time synchronization provided by a specific node. Upon failure of this node, the entire network cannot communicate. Butler removes this single point of failure by quickly synchronizing all nodes in the network without affecting the protocols’ performance. In the second part, we focus on the challenges of integrating communication and various control concepts using classical time-triggered and modern event-based approaches. Based on the design, implementation, and evaluation of the proposed solutions using real systems and networks, we make the following contributions, which in many ways push the boundaries of previous approaches: • We are the first to demonstrate and evaluate fast feedback control over low-power wireless multi-hop networks. Essential for this achievement is a novel co-design and integration of communication and control. Our wireless embedded platform tames the imperfections impairing control, for example, message loss and varying delays, and considers the resulting key properties in the control design. Furthermore, the careful orchestration of control and communication tasks enables real-time operation and makes our system amenable to an end-to-end analysis. Due to this, we can provably guarantee closed-loop stability for physical processes with linear time-invariant dynamics. • We propose control-guided communication, a novel co-design for distributed self-triggered control over wireless multi-hop networks. Self-triggered control can save energy by transmitting data only when needed. However, there are no solutions that bring those savings to multi-hop networks and that can reallocate freed-up resources, for example, to other agents. Our control system informs the communication system of its transmission demands ahead of time so that communication resources can be allocated accordingly. Thus, we can transfer the energy savings from the control to the communication side and achieve an end-to-end benefit. • We present a novel co-design of distributed control and wireless communication that resolves overload situations in which the communication demand exceeds the available bandwidth. As systems scale up, featuring more agents and higher bandwidth demands, the available bandwidth will be quickly exceeded, resulting in overload. While event-triggered control and self-triggered control approaches reduce the communication demand on average, they cannot prevent that potentially all agents want to communicate simultaneously. We address this limitation by dynamically allocating the available bandwidth to the agents with the highest need. Thus, we can formally prove that our co-design guarantees closed-loop stability for physical systems with stochastic linear time-invariant dynamics.:Abstract Acknowledgements List of Abbreviations List of Figures List of Tables 1 Introduction 1.1 Motivation 1.2 Application Requirements 1.3 Challenges 1.4 State of the Art 1.5 Contributions and Road Map 2 Mixer: Efficient Many-to-All Broadcast in Dynamic Wireless Mesh Networks 2.1 Introduction 2.2 Overview 2.3 Design 2.4 Implementation 2.5 Evaluation 2.6 Discussion 2.7 Related Work 3 Butler: Increasing the Availability of Low-Power Wireless Communication Protocols 3.1 Introduction 3.2 Motivation and Background 3.3 Design 3.4 Analysis 3.5 Implementation 3.6 Evaluation 3.7 Related Work 4 Feedback Control Goes Wireless: Guaranteed Stability over Low-Power Multi-Hop Networks 4.1 Introduction 4.2 Related Work 4.3 Problem Setting and Approach 4.4 Wireless Embedded System Design 4.5 Control Design and Analysis 4.6 Experimental Evaluation 4.A Control Details 5 Control-Guided Communication: Efficient Resource Arbitration and Allocation in Multi-Hop Wireless Control Systems 5.1 Introduction 5.2 Problem Setting 5.3 Co-Design Approach 5.4 Wireless Communication System Design 5.5 Self-Triggered Control Design 5.6 Experimental Evaluation 6 Scaling Beyond Bandwidth Limitations: Wireless Control With Stability Guarantees Under Overload 6.1 Introduction 6.2 Problem and Related Work 6.3 Overview of Co-Design Approach 6.4 Predictive Triggering and Control System 6.5 Adaptive Communication System 6.6 Integration and Stability Analysis 6.7 Testbed Experiments 6.A Proof of Theorem 4 6.B Usage of the Network Bandwidth for Control 7 Conclusion and Outlook 7.1 Contributions 7.2 Future Directions Bibliography List of Publication

    20th SC@RUG 2023 proceedings 2022-2023

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    Concept-aware clustering for decentralized deep learning under temporal shift

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    Decentralized deep learning requires dealing with non-iid data across clients, which may also change over time due to temporal shifts. While non-iid data has been extensively studied in distributed settings, temporal shifts have received no attention. To the best of our knowledge, we are first with tackling the novel and challenging problem of decentralized learning with non-iid and dynamic data. We propose a novel algorithm that can automatically discover and adapt to the evolving concepts in the network, without any prior knowledge or estimation of the number of concepts. We evaluate our algorithm on standard benchmark datasets and demonstrate that it outperforms previous methods for decentralized learning.Comment: 4 pages, 2 figure

    Towards Sybil Resilience in Decentralized Learning

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    Federated learning is a privacy-enforcing machine learning technology but suffers from limited scalability. This limitation mostly originates from the internet connection and memory capacity of the central parameter server, and the complexity of the model aggregation function. Decentralized learning has recently been emerging as a promising alternative to federated learning. This novel technology eliminates the need for a central parameter server by decentralizing the model aggregation across all participating nodes. Numerous studies have been conducted on improving the resilience of federated learning against poisoning and Sybil attacks, whereas the resilience of decentralized learning remains largely unstudied. This research gap serves as the main motivator for this study, in which our objective is to improve the Sybil poisoning resilience of decentralized learning. We present SybilWall, an innovative algorithm focused on increasing the resilience of decentralized learning against targeted Sybil poisoning attacks. By combining a Sybil-resistant aggregation function based on similarity between Sybils with a novel probabilistic gossiping mechanism, we establish a new benchmark for scalable, Sybil-resilient decentralized learning. A comprehensive empirical evaluation demonstrated that SybilWall outperforms existing state-of-the-art solutions designed for federated learning scenarios and is the only algorithm to obtain consistent accuracy over a range of adversarial attack scenarios. We also found SybilWall to diminish the utility of creating many Sybils, as our evaluations demonstrate a higher success rate among adversaries employing fewer Sybils. Finally, we suggest a number of possible improvements to SybilWall and highlight promising future research directions
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