Persistence Bag-of-Words for Topological Data Analysis

Persistent homology (PH) is a rigorous mathematical theory that provides a robust descriptor of data in the form of persistence diagrams (PDs). PDs exhibit, however, complex structure and are difficult to integrate in today's machine learning workflows. This paper introduces persistence bag-of-words: a novel and stable vectorized representation of PDs that enables the seamless integration with machine learning. Comprehensive experiments show that the new representation achieves state-of-the-art performance and beyond in much less time than alternative approaches.Comment: Accepted for the Twenty-Eight International Joint Conference on Artificial Intelligence (IJCAI-19). arXiv admin note: substantial text overlap with arXiv:1802.0485

Data-Driven Grasp Synthesis - A Survey

We review the work on data-driven grasp synthesis and the methodologies for sampling and ranking candidate grasps. We divide the approaches into three groups based on whether they synthesize grasps for known, familiar or unknown objects. This structure allows us to identify common object representations and perceptual processes that facilitate the employed data-driven grasp synthesis technique. In the case of known objects, we concentrate on the approaches that are based on object recognition and pose estimation. In the case of familiar objects, the techniques use some form of a similarity matching to a set of previously encountered objects. Finally for the approaches dealing with unknown objects, the core part is the extraction of specific features that are indicative of good grasps. Our survey provides an overview of the different methodologies and discusses open problems in the area of robot grasping. We also draw a parallel to the classical approaches that rely on analytic formulations.Comment: 20 pages, 30 Figures, submitted to IEEE Transactions on Robotic

Persistence codebooks for topological data analysis

Persistent homology is a rigorous mathematical theory that provides a robust descriptor of data in the form of persistence diagrams (PDs) which are 2D multisets of points. Their variable size makes them, however, difficult to combine with typical machine learning workflows. In this paper we introduce persistence codebooks, a novel expressive and discriminative fixed-size vectorized representation of PDs that adapts to the inherent sparsity of persistence diagrams. To this end, we adapt bag-of-words, vectors of locally aggregated descriptors and Fischer vectors for the quantization of PDs. Persistence codebooks represent PDs in a convenient way for machine learning and statistical analysis and have a number of favorable practical and theoretical properties including 1-Wasserstein stability. We evaluate the presented representations on several heterogeneous datasets and show their (high) discriminative power. Our approach yields comparable-and partly even higher-performance in much less time than alternative approaches

Beyond Visual Words: Exploring Higher - Level Image Representation For Object Categorization

Ph.DDOCTOR OF PHILOSOPH

Negotiating (Inter)Disciplinary Identity in Integrative Graduate Education

abstract: Identity, or peoples’ situated sense of self, can be conceptualized and operationalized in a myriad of ways, including, among others, a person’s gender, socioeconomic status, degree of expertise, nationality, and disciplinary training. This study conceptualizes identity as fluid and constructed through social interaction with others, where individuals ask themselves “Who am I?” in relation to the people around them. Such a discursive conceptualization argues that we can observe peoples’ performance of identity through the close reading and examination of their talk and text. By discursively drawing boundaries around descriptions of “Who I am,” people inherently attribute value to preferred identities and devalue undesirable, “other” selves. This study analyzes ten workshops from the Toolbox Project conducted with graduate student scientists participating in the Integrative Graduate Education Research Traineeship (IGERT) program. The emotional tone, mood, and atmosphere of shared humor and laughter emerged as a context through which collaborators tested the limits of different identities and questioned taken for granted assumptions about their disciplinary identities and approaches to research. Through jokes, humorous comments, sarcasm, and laughter, students engaged in three primary forms of othering: 1) unifying the entire group against people outside the group, 2) differentiating group members against each other, and 3) differentiating oneself in comparison to the rest of the group. I use action-implicative discourse analysis to reconstruct these communicative practices at three levels—problem, technical, and philosophical—and explore the implications of group laughter and humor as sites of “othering” discursive strategies in graduate students’ efforts to negotiate and differentiate identity in the context of integrative collaboration.Dissertation/ThesisDoctoral Dissertation Communication 201

Snowedout Atlanta: An Analysis of how Stakeholders Engaged in a Facebook Online Support Group During a Crisis

In 2014, snowstorms hit the southern U.S. and paralyzed the Atlanta, Georgia metropolitan area. The people of Atlanta and the surrounding areas accessed a Facebook group page, SnowedOut Atlanta (SOA), and some used it to strategically survive the storm. The social media posts produced by the residents of Atlanta before and after the storm provide a rich case of study for health-related, crisis Communication and social media scholars. The objective of this thesis was to investigate the use of social media for the SOA Facebook group through the analyses of wall posts. In order to explore this line of inquiry, quantitative analyses were conducted. The study examined one online support group through a content analysis of member posts to the SOA Facebook page. This analysis examined the uses of affective and cognitive needs of members of an online support group during a crisis event through the lens of uses and gratification theory (Katz et al., 1973). A total of 986 posts were coded for seven categorical variables. The content analysis yielded interesting results that shed light on the adoption of social media during a crisis or disastrous event. The results concluded that the SOA Facebook page was used to satisfy more cognitive needs as oppose to affective needs. Analyses also indicated that women posted to the page more than men. This research had many implications for health and risk Communication professionals. Future research should aim to develop a deeper understanding of why and how social media supports strategic and tactical risk Communication efforts a community, organization or corporation may employ during a disastrous or crisis event

Data-Driven Grasp Synthesis—A Survey

We review the work on data-driven grasp synthesis and the methodologies for sampling and ranking candidate grasps. We divide the approaches into three groups based on whether they synthesize grasps for known, familiar, or unknown objects. This structure allows us to identify common object representations and perceptual processes that facilitate the employed data-driven grasp synthesis technique. In the case of known objects, we concentrate on the approaches that are based on object recognition and pose estimation. In the case of familiar objects, the techniques use some form of a similarity matching to a set of previously encountered objects. Finally, for the approaches dealing with unknown objects, the core part is the extraction of specific features that are indicative of good grasps. Our survey provides an overview of the different methodologies and discusses open problems in the area of robot grasping. We also draw a parallel to the classical approaches that rely on analytic formulations

A influência das alterações climáticas na escalada do conflito comunal entre pastores e agricultores: o caso da etnia Fulani na Nigéria

Current scientific evidence shows that human activities are causing interference at different levels in the global climate and availability of natural resources, and many authors already relate water scarcity to the increased risk of violent conflict, particularly i n rural societies on the African continent. Climate disruptions caused by climate change are reflected on a regional and local scale, and the greatest impacts are already being felt in the poorest areas of the planet. Nigeria, Africa's most populous country, has been facing environmental problems in its territory that can be associated with climate change, such as rising temperatures, reduced rainfall and advancing desertification. Considering that all these phenomena have been worsening since the early twentieth century in Nigeria and, due to the escalating of violent conflicts since the beginning of the current century, the objective of this paper is to analyse how climate change can interfere in the conflict between herdsmen and farmers, as well as the possible impact of seasonal variation in rainfall on the dynamics of these communal conflicts. The study focused on literature review and the case study took place in four Nigerian states (Plateau, Benue, Taraba and Nasarawa) for the period 2010-2017, focusing on the communal conflict involving the Fulani ethnic group. The approach adopted was the inductive method in which the behaviour of rainfall in the study area was compared with the number of deaths resulting from the conflict, in addition to using geo-processing software to understand the spatial and temporal distribution of casualties. The theoretical framework used was that proposed by Thomas Homer-Dixon (1994) and the information was collected from primary sources, with consultation of qualitative and quantitative data, and from secondary sources through book reviews, publications and papers in scientific journals. While it is not yet possible to establish a direct and linear relationship between climate change and violent conflict, the revised literature indicates that competition for water and other natural resources in certain parts of Nigeria is increasing, and that the violent conflicts between Fulani herdsmen and farmers are increasing due to the dispute over access to water sources and g razing lands. Data analysis shows that in the study area there are 46.4% more deaths in the dry season (November to April) than in the rainy season (May to October). While there are still not enough elements to conclude that climate change is the primary cause of the conflict, the analysis reinforces the need, in certain contexts, particularly in developing countries with populations highly dependent on the primary sector of the economy, for the impacts of climate change to be seriously considered as a risk to human security