Economics of Technology

Probing life scripts for important life events in a multi-ethnic society

Modelling life trajectories and mode choice using Bayesian belief networks

A high spatial resolution residential energy model based on American Time Use Survey data and the bootstrap sampling method

Ad hoc wireless networks have emerged as a solution to providing ubiquitous, on-demand connectivity without the need for significant infrastructure deployment. In this thesis we address the privacy problems in two types of emerging wireless ad hoc networks, namely sensor and vehicular networks. Although the content of sensor messages describing “events of interest” may be encrypted to provide confidentiality, the context surrounding these events may also be sensitive and therefore should be protected from eavesdroppers. The source-location privacy problem occurs in sensor networks when adversaries use RF localization techniques to perform hop-by-hop traceback of messages to the source sensor’s location. Our work provides a formal model for this problem and examines the privacy characteristics of different sensor routing protocols. In order to provide efficient and private sensor communications, we devise new techniques to enhance source-location privacy that augment these routing protocols. Similarly, an adversary armed with knowledge of the network deployment, routing algorithms, and the data sink location can infer the temporal patterns and track the spatio-temporal evolution of a sensed event, by monitoring the packet arrivals at the sink. We introduce the temporal privacy problem for delay-tolerant sensor networks, provide an information theoretic formulation and propose adaptive buffering to obfuscate temporal information from the adversary. Sensor networks are also characterized by distinctive traffic patterns, wherein traffic mostly exists when events of interests occur. Due to the direct correlation between the type of event and size of data generated by it, an adversary observing a traffic burst can infer information about the type of event simply from the observed message size. We formulate this traffic privacy problem in terms of information entropy, present a quantifiable means to measure traffic privacy and propose solutions to enhance it. Vehicular ad hoc networks represent a promising new communication paradigm that can facilitate many new forms of automotive applications. We present a robust and efficient security and privacy framework, for such networks, that uses identity-based cryptography. We show that our framework provides authentication, confidentiality, non-repudiation and message-integrity. Further, it supports scalable, user-customizable privacy through short-lived, unforgeable, pseudonyms.

Secondary Childcare in the Atus: What Does it Measure?

Early events in folding can determine if a protein is going to fold, misfold, or aggregate. Understanding these deterministic events is paramount for de novo protein engineering, the enhancement of biopharmaceutical stabilities, and understanding neurodegenerative diseases including amyotrophic lateral sclerosis and Alzheimer's disease. However, the physicochemical and structural biases within high energy states of protein biopolymers are poorly understood. A combined experimental and computational study was conducted on the small β/α-repeat protein CheY to determine the structural basis of its submillisecond misfolding reaction to an off-pathway intermediate. Using permutations, we were able to discriminate between the roles of two proposed mechanisms of folding; a nucleation condensation model, and a hydrophobic collapse model driven by the formation of clusters of isoleucine, leucine, and valine (ILV) residues. We found that by altering the ILV cluster connectivity we could bias the early folding events to either favor on or off-pathway intermediates. Structural biases were also experimentally observed in the unfolded state of a de novo designed synthetic β/α-repeat protein, Di-III_14. Although thermodynamically and kinetically 2-state, Di-III_14 has a well structured unfolded state that is only observable under native-favoring conditions. This unfolded state appears to retain native-like structure, consisting of a hydrophobic 7 core (69% ILV) stabilized by solvent exposed polar groups and long range electrostatic interactions. Together, these results suggest that early folding events are largely deterministic in these two systems. Generally, low contact order ILV clusters favor local compaction and, in specific cases, long range electrostatic interactions may have stabilizing effects in higher energy states.

This paper provides two puzzles for a theory of aspect. The first concerns the quirky behavior of the Russian imperfective with regard to its culmination properties: it seems to function like the perfect aspect in certain cases, but like the progressive in others. The other puzzle concerns how the Russian imperfective constrains the temporal location of a described event: it relates distinct event parts to a given temporal parameter. Which part is at play depends on how this parameter is specified. If it is specified by an adverbial, then an event is located in time. If it is specified by the discourse context, then a consequent state is located in time. I solve the former puzzle by appealing to the structure of atomic vs. non-atomic events and solve the latter by appealing to two temporal inputs required by an aspectual marker. These inputs reveal that aspectual meaning involves both temporal information and information about discourse connectivity.

With the broader dissemination of digital technologies, visionary concepts like the Internet of Things also affect an increasing number of use cases with interfaces to humans, e.g. manufacturing environments with technical operators monitoring the processes. This leads to additional challenges, as besides the technical issues also human aspects have to be considered for a successful implementation of strategic initiatives like Industrie 4.0. From a technical perspective, complex event processing has proven itself in practice to be capable of integrating and analyzing huge amounts of heterogeneous data and establishing a basic level of situation awareness by detecting situations of interests. Whereas this reactive nature of complex event processing systems may be sufficient for machine-to-machine use cases, the new characteristic of application fields with humans remaining in the control loop leads to an increasing action distance and delayed reactions. Taking human aspects into consideration leads to new requirements, with transparency and comprehensibility of the processing of events being the most important ones. Improving the comprehensibility of complex event processing and extending its capabilities towards an effective support of human operators allows tackling technical and non-technical challenges at the same time. The main contribution of this thesis answers the question of how to evolve state-of-the-art complex event processing from its reactive nature towards a transparent and holistic situation management system. The goal is to improve the interaction among systems and humans in use cases with interfaces between both worlds. Realizing a holistic situation management requires three missing capabilities to be introduced by the contributions of this thesis: First, based on the achieved transparency, the retrospective analysis of situations is enabled by collecting information related to a situation's occurrence and development. Therefore, CEP engine-specific situation descriptions are transformed into a common model, allowing the automatic decomposition of the underlying patterns to derive partial patterns describing the intermediate states of processing. Second, by introducing the psychological model of situation awareness into complex event processing, human aspects of information processing are taken into consideration and introduced into the complex event processing paradigm. Based on this model, an extended situation life-cycle and transition method are derived. The introduced concepts and methods allow the implementation of the controlling function of situation management and enable the effective acquisition and maintenance of situation awareness for human operators to purposefully direct their attention towards upcoming situations. Finally, completing the set of capabilities for situation management, an approach is presented to support the generation and integration of prediction models for predictive situation management. Therefore, methods are introduced to automatically label and extract relevant data for the generation of prediction models and to enable the embedding of the resulting models for an automatic evaluation and execution. The contributions are introduced, applied and evaluated along a scenario from the manufacturing domain.

We examine monthly variation in weekly work hours using data from 2003 to 2010. The data sources include the Current Population Survey (CPS) on hours/worker, the Current Employment Survey (CES) on hours/job, and the American Time Use Survey (ATUS) on both. The ATUS data minimize recall difficulties and constrain hours of work to accord with total available time. The ATUS hours/worker are less cyclical than the CPS series, but the hours/job are more cyclical than the CES series. We present alternative estimates of productivity based on ATUS data, and find that it is more pro-cyclical than other productivity measures.

SummaryThe American Time Use Survey (ATUS) accurately measures hours worked on a single day. We propose several estimators of elasticities of weekly labor supply in a linear regression model, despite certain impossibility results due to the time specific feature of the ATUS. We recommend the impute estimator, a simple modification of the standard two stage least squares estimator, that imputes the dependent variable using daily subsamples, based on our careful investigation of asymptotic and finite sample properties of the estimators under the potential outcome framework. We apply the impute estimator to the ATUS and find substantially different elasticity estimates from the Current Population Survey, especially for married women.

The authors argue that both the large variability in survey estimates of volunteering and the fact that survey estimates do not show the secular decline common to other social capital measures are caused by the greater propensity of those who do volunteer work to respond to surveys. Analyses of the American Time Use Survey (ATUS)--the sample for which is drawn from the Current Population Survey (CPS)--together with the CPS volunteering supplement show that CPS respondents who become ATUS respondents report much more volunteering in the CPS than those who become ATUS nonrespondents. This difference is replicated within subgroups. Consequently, conventional adjustments for nonresponse cannot correct the bias. Although nonresponse leads to estimates of volunteer activity that are too high, it generally does not affect inferences about the characteristics of volunteers.

This study examines the ways in which the Internet is utilized for progressive civic action, focusing on a detailed case study of Internet activism of South Korea. The goals of this study are to examine: the ways in which the Internet is utilized for progressive civic action; the extent to which Internet activism is differentiated from preexisting social movements; and the ways in which the Internet affects movement repertoires and organizational forms of civic action. Toward this end, this study encompasses four main areas: (1) historical background of Korean Internet activism; (2) social agents of Internet activism; (3) movement repertoires and awareness of citizenship; and (4) theoretical implications of the Korean case. This study employs multiple research methods including qualitative framing analysis, in-depth interviews, and focus-group interviews as well as quantitative methods. The findings of this study suggest that Korean Internet activism has had a huge impact on political and cultural environments. Korea’s liberal and critical younger generations have predominantly used the Internet, constituting amorphous and hybrid groups of Internet users who are aware of citizenship—namely netizens. Positing themselves distinctly from preexisting activist groups including social movement organizations (SMOs), Korean netizens have utilized the Internet for resource mobilization, virtual struggles, and alternative knowledge production for progressive civic action. Through serial events from 2002 to 2007, Korean netizens and SMOs have collaborated on the one hand and contended on the other hand. Netizens have expedited horizontal and decentralized networks for communication and mobilization while SMOs have maintained hierarchical organizational forms and centralized leadership. This study also found that Korean Internet activism has brought about noticeable changes in movement repertoires. Netizens have organically combined online and offline struggles, converged sub-cultural and political discourses, and constructed distributed trust and counter-hegemonic frames through interactive communications based on datgul [replies] and pumjil [copy-and-paste]. Different from Chadwick’s hybrid mobilization movement model based on Western experience, organizational innovations of civic action have mainly been led by netizens, rather than by SMOs. While many Korean SMOs have adopted new movement repertoires for resource mobilization, they have failed to internalize new values embedded in the netizens’ movement repertoires.%%%%

Rainfall intensity for a particular frequency and duration is one of the most important parameter for the hydrologic design of dam, reservoirs, storm sewers, culverts and many other hydraulic structures. This can be obtained from Intensity-Duration-Frequency (IDF) relationship, which is determined by frequency analysis of rainfall data. The goal of this research is to develop rainfall intensity-duration frequency relationship for the data scarce urbanized Guma catchment in Freetown the capital city of Sierra Leone using the Gumbel and Pearson Type III distributions. To achieve this goal, daily rainfall data for the period of 1991 to 2018 for the Guma catchment rainfall station was obtained from the Guma Valley Water Company and were converted to shorter duration (hourly) using the Indian Meteorological Department (IMD) method. Twenty-eight maximum daily rainfall events were converted to hourly rainfall events. Frequency analysis was conducted to develop the rainfall intensity-duration-frequency relationships using the Gumbel and Pearson Type III distributions. The Kolmogorov-Smirnov (K-S) goodness of fit test was utilized to determine which of the distributions have a better fit at 5 and 10% significant levels. The frequency analysis results show that the Gumbel distribution gives higher intensity for all return periods and durations than the Pearson Type III distribution. The result of the K-S goodness of fit test shows that all of the data fit the Gumbel distribution for different return periods (2, 5, 10, 25, 50 and 100 years) at the level of significance of which yield and which yield while the data do not give good fit using the Pearson Type III distribution at both levels of significance for the different return periods. Key words: Rainfall, Intensity-duration-frequency relationships, probability distributions, goodness of fit test.

textabstractThis paper proposes to understand the globalizing of online Social Network Sites (SNS) through the spatial metaphor of global parks. It builds upon a commonly accepted ideation of the city as socially-constructed and that which has been harnessed to understand the spatiality of the Internet. Over the decades we have learnt to conceptualize the Internet with the aid of metaphors, including that of the city to grasp its intricate information highways, networks and connectivity, the underlying logic that dictates movement within these spaces and nodes of concentrated social action. By equating the Internet to the city, we are compelled to extend our imagination by applying our understandings of urban planning and geography to current vital conversations on the shaping of Internet spaces. The persistence of this parallel has matured our thinking significantly from the utopic notion of the web as a frontier of limitless and depoliticized space to a more architected and socio-economic phenomenon of a propertied and contextual digital place. Given that the city has been a useful analogy for the Internet to confront its directionality and political intent in design and usage, this paper takes this parallel further, delving into a segment of the Internet that is currently in the midst of tremendous speculation- that of Social Network Sites (SNS) and its seemingly open, democratic, social and inclusive nature. If we narrow our attention to a domain of the city that is imbued with a similar rhetoric of being open, social and leisurely, we find ourselves in the presence of urban parks. By drawing this linkage, we become aware of the deeply historical and transnational character of public leisure spaces. This paper takes this dialogue further by investigating the globalization of the Internet and that of social network sites. This argument uses the metaphorical parallel of the city = Internet as a starting point and capitalizes on the rich literature surrounding the globalization of the cityscape or what is popularly referred to as the global city; these are spaces that serve as a fulcrum for the industrial, the creative, the leisurely, and the privileged as well as the temporal laboring and migrant class. This effort allows us to constructively borrow from the field of urban studies and extend important debates surrounding globalization of the material domain to its virtual counterpart- the Internet and its social network sites to better confront the political, socio-cultural and economic dimensions of globalization and its online/offline intermediations.

I. Chapter 1 presents a convenient notation for describing methods of aggregating information to form posterior distributions, allowing a description of Bayesian updating and many of the cognitive errors people commit in the lab. Chapter 2 looks at the monotone ordering problem: if the prior distributions are ordered in some manner, what updating operations will preserve that ordering? Bayesian updating is a member of a small class of operators which preserve the monotone likelihood ratio property, but is not in the class of functions which preserve first-order stochastic dominance. It also considers ordering distributions by their medians, which is useful for Political Science and other decisionmaking applications. II. Chapter 3 presents a literature review of existing models of information aggregation from one party, and gives the very weak conditions under which one or two biased advocates will always reveal full information. Chapter 4 then presents a model of a trial, in which events are grouped into causal stories. Each story may point to a specific verdict, but the judge has leeway in selecting a verdict when multiple stories are shown to simultaneously be sufficient to explain an event. Two judges may be `perfect Bayesians', share the same priors, and still arrive at different verdicts for the same trial. Unlike the information revelation literature to date, there may be apropos stories and facts that neither party will want to reveal in equilibrium. III. Chapter 5 presents a simultaneous model of goods or actions which demonstrate conformity effects. Previous models of such goods universally describe people as acting in sequence; actors in the model here act simultaneously, so they must decide what to do based only on prior information about the distribution of tastes in the society. The shape of this distribution (e.g., centered around zero, skewed upward, or fat-tailed) predicts the number of people who will act in some systematic ways, which I catalog here.