Recency predicts bursts in the evolution of author citations

The citations process for scientific papers has been studied extensively. But while the citations accrued by authors are the sum of the citations of their papers, translating the dynamics of citation accumulation from the paper to the author level is not trivial. Here we conduct a systematic study of the evolution of author citations, and in particular their bursty dynamics. We find empirical evidence of a correlation between the number of citations most recently accrued by an author and the number of citations they receive in the future. Using a simple model where the probability for an author to receive new citations depends only on the number of citations collected in the previous 12-24 months, we are able to reproduce both the citation and burst size distributions of authors across multiple decades.Comment: 12 pages, 7 figure

Implications of Computational Cognitive Models for Information Retrieval

This dissertation explores the implications of computational cognitive modeling for information retrieval. The parallel between information retrieval and human memory is that the goal of an information retrieval system is to find the set of documents most relevant to the query whereas the goal for the human memory system is to access the relevance of items stored in memory given a memory probe (Steyvers & Griffiths, 2010). The two major topics of this dissertation are desirability and information scent. Desirability is the context independent probability of an item receiving attention (Recker & Pitkow, 1996). Desirability has been widely utilized in numerous experiments to model the probability that a given memory item would be retrieved (Anderson, 2007). Information scent is a context dependent measure defined as the utility of an information item (Pirolli & Card, 1996b). Information scent has been widely utilized to predict the memory item that would be retrieved given a probe (Anderson, 2007) and to predict the browsing behavior of humans (Pirolli & Card, 1996b). In this dissertation, I proposed the theory that desirability observed in human memory is caused by preferential attachment in networks. Additionally, I showed that documents accessed in large repositories mirror the observed statistical properties in human memory and that these properties can be used to improve document ranking. Finally, I showed that the combination of information scent and desirability improves document ranking over existing well-established approaches

Unveiling the path towards sustainability: scientific interest at HEIs from a scientometric approach in the period 2008-2017

Mención Internacional en el título de doctorLa humanidad ha experimentado el impacto de un modelo económico insostenible a todos los niveles. Este tema se ha cristalizado en diferentes cumbres y conferencias durante el siglo XX. Como resultado de esta preocupación, surgió el concepto de Desarrollo Sostenible (DS). Sin embargo, este concepto ha recibido muchas críticas por ser altamente antropocéntrico y compartimentado, carente de coherencia conceptual o interconexión entre todos los aspectos involucrados. Más tarde, la aparición de los Objetivos de Desarrollo del Milenio (ODM) en 2000 y los recientes Objetivos de Desarrollo Sostenible (ODS) en 2015 constituyen una nueva era. Este es el plan para lograr un futuro mejor y más sostenible para todos, en el que todos los agentes involucrados deben participar. En este punto, las instituciones de educación superior (IES) tienen un papel central y la sostenibilidad se ha convertido en una prioridad política para la ciencia. El objetivo de este estudio es conocer los patrones de la investigación llevada a cabo en investigación de sostenibilidad, incluido el flujo de actividad científica, así como la colaboración o el impacto que genera dicha investigación. Este estudio de doctorado explora cómo se puede delinear este concepto desde un enfoque bibliométrico, lo cual conduce a la ‘ciencia de la sostenibilidad’. La producción científica de artículos fue identificada y analizada en el período 2008-2017 en la Web of Science (WoS). Además, este estudio explora las instituciones de educación superior (IES) y su papel en el fomento de la sostenibilidad, mediante la evaluación de su investigación y la implementación de prácticas de sostenibilidad en las IES españolas. Además, presenta una delineación de los Objetivos de Desarrollo Sostenible (ODS) y propone una metodología para clasificar la producción científica en cada uno e los objetivos. El análisis de esta producción se realiza a través de indicadores bibliométricos unidimensionales y multidimensionales. Estos indicadores se han dividido y analizado en diferentes niveles de agregación, desde el más general hasta el más específico, comenzando con las características generales de investigación y descendiendo al nivel de país, instituciones o temática, entre otros. Los resultados muestran un interés creciente en la investigación de sostenibilidad y se observa una fuerte influencia del pilar medioambiental. Además, hay países con una alta producción científica pero no tan especializados en el tema como otros con una menor producción. En cuanto a las instituciones, los resultados obtenidos muestran que las IES realizaron un importante esfuerzo de investigación para el desarrollo sostenible y son las que producen un mayor número de documentos. Además, se observa que las instituciones tienden a colaborar con centros geográficamente próximos. Al analizar las Prácticas de sostenibilidad en las IES españolas, se encuentran asociaciones altas entre variables como la presencia de un Plan de Sostenibilidad y de una Oficina Verde. Sin embargo, este estudio demuestra claramente que, aunque se reconoce que el desarrollo sostenible es muy importante para las IES y la sociedad, todavía no está integrado en las estrategias, actividades y políticas de todo el sistema. Como conclusión, se afirma que es esencial identificar estrategias de sostenibilidad e introducir desarrollo sostenible en todas las actividades en el entorno de las IES. Finalmente, esta tesis contribuye a la literatura sobre instituciones de educación superior sostenibles, así como al análisis y la mejora de educación superior para el desarrollo sostenible, especialmente en el sistema de educación superior español. Además, este estudio contribuye al análisis bibliométrico al ofrecer dos propuestas de delineación científica para la ciencia de la sostenibilidad y los objetivos de desarrollo sostenible, así como metodologías para clasificar la producción científica. Este análisis denota la importancia de los estudios bibliométricos para el estudio y la caracterización de la producción científica en un campo transdisciplinario que, además, se puede extrapolar a otros campos de estudio.Humanity has experienced the impact of an unsustainable economic model at all levels. This topic has crystallized in different summits and conferences during the 20th century. As a result of this concern, the concept of sustainable development (SD) emerged. However, it has received much criticism for being highly anthropocentric and compartmentalized, and lacking conceptual coherence or interconnectedness among all the aspects involved. The introduction of the Millennium Development Goals (MDGs) in 2000 and the recent Sustainable Development Goals (SDGs) in 2015 heralded a new era. They represent a blueprint to achieve a better and more sustainable future for all, in which all stakeholders need to be involved. At this point, higher education institutions (HEIs) have a central role to play and sustainability has emerged as a policy priority for science. The objective of this study is to investigate the patterns of sustainability research, including the flow of scientific activity, as well as the collaboration or impact that such research generates. This doctoral study explores how can sustainability can be delineated from a bibliometric approach, leading to a new approach of “sustainability science”. The scientific production of articles was identified and analysed for the period 2008–2017 using the Web of Science (WoS). Moreover, this research study explores HEIs and their role in fostering sustainability, by assessing their research and the implementation of sustainability practices in Spanish HEIs. As well, it presents a delineation of the Sustainable Development Goals (SDGs) and proposes a methodology for classifying the output on each SDG. This analysis is done through unidimensional and multidimensional bibliometric indicators. These indicators have been divided and analysed in different levels of aggregation, from the most general to the most specific, starting with general research features and progressing to country, institutional, and thematic levels, among others. The results indicate a growing interest in sustainability research and a strong influence on the environmental pillar. Moreover, some countries with the highest scientific output are not as specialized in terms of topics as others with a lower output. Regarding institutions, the results obtained indicate that HEIs made an important research contribution to SD and are the ones that produce a higher number of documents. It was found that institutions tend to collaborate with other institutions that are close. By analysing sustainability practices in Spanish HEIs, it was found that there are more associations between variables such as having a sustainability plan and having a green office. However, this study clearly demonstrates that although SD is recognized as being very important to HEIs and society, it is not yet embedded in the whole system’s strategies, activities, and policies. In conclusion, this research study reveals that it is essential to identify sustainability strategies and introduce SD in all activities in the HEI environment. Finally, this thesis contributes to the literature on sustainable HEIs, as well as to how higher education for SD is understood and can be improved, especially in the Spanish higher education system. Moreover, this contributes to bibliometric study by offering two delineation approach to sustainability science and sustainable development goals as well as methodologies for classifying scientific output. This denotes the importante of bibliometric studies for the study and characterization of scientific output in a transdisciplinary field that can be extrapolated to other fields of study.Programa de Doctorado en Documentación: Archivos y Bibliotecas en el Entorno Digital por la Universidad Carlos III de MadridPresidente: Carlos Balaguer Bernaldo de Quirós.- Secretario: Birger Larsen.- Vocal: Sandra Sofía Ferreira Da Silva C

Predictive Modeling for Navigating Social Media

Social media changes the way people use the Web. It has transformed ordinary Web users from information consumers to content contributors. One popular form of content contribution is social tagging, in which users assign tags to Web resources. By the collective efforts of the social tagging community, a new information space has been created for information navigation. Navigation allows serendipitous discovery of information by examining the information objects linked to one another in the social tagging space. In this dissertation, we study prediction tasks that facilitate navigation in social tagging systems. For social tagging systems to meet complex navigation needs of users, two issues are fundamental, namely link sparseness and object selection. Link sparseness is observed for many resources that are untagged or inadequately tagged, hindering navigation to the resources. Object selection is concerned when there are a large number of information objects that are linked to the current object, requiring to select the more interesting or relevant ones for guiding navigation effectively. This dissertation focuses on three dimensions, namely the semantic, social and temporal dimensions, to address link sparseness and object selection. To address link sparseness, we study the task of tag prediction. This task aims to enrich tags for the untagged or inadequately tagged resources, such that the predicted tags can serve as navigable links to these resources. For this task, we take a topic modeling approach to exploit the latent semantic relationships between resource content and tags. To address object selection, we study the task of personalized tag recommendation and trend discovery using social annotations. Personalized tag recommendation leverages the collective wisdom from the social tagging community to recommend tags that are semantically relevant to the target resource, while being tailored to the tagging preferences of individual users. For this task, we propose a probabilistic framework which leverages the implicit social links between like-minded users, i.e. who show similar tagging preferences, to recommend suitable tags. Social tags capture the interest of the users in the annotated resources at different times. These social annotations allow us to construct temporal profiles for the annotated resources. By analyzing these temporal profiles, we unveil the non-trivial temporal trends of the annotated resources, which provide novel metrics for selecting relevant and interesting resources for guiding navigation. For trend discovery using social annotations, we propose a trend discovery process which enables us to analyze trends for a multitude of semantics encapsulated in the temporal profiles of the annotated resources

Online discussions through the lens of interaction patterns

Computer-mediated communication is arguably prevailing over face-to-face. However, many of the subtleties that make in-person communication personal, cues such as an ironic tone of voice or an effortless posture, are inherently impossible to render through a screen. The context vanishes from the conversation - what is left is therefore mostly text, enlivened by occasional multimedia. At least, this seems the dominant opinion of both industry and academia, that recently focused considerable resources on a deeper understanding of natural and visual language. I argue instead that richer cues are missing from online interaction only because current applications do not acknowledge them -- indeed, communication online is already infused with nonverbal codes, and the effort needed to leverage them is well worth the amount of information they carry. This dissertation therefore focuses on what is left out of the traditional definition of content: I refer to these aspects of communication as content-agnostic. Specifically, this dissertation makes three contributions. First, I formalize what constitutes content-agnostic information in computer-mediated communication, and prove content-agnostic information is as personal to each user as its offline counterpart. For this reason, I choose as a venue of research the web forum, a supposedly text-based, impersonal communication environment, and show that it is possible to attribute a message to the corresponding author solely on the basis of its content-agnostic features -- in other words, without looking at the content of the message at all. Next, I display how abundant and how varied is the content-agnostic information that lies untapped in current applications.To this end, I analyze the content-agnostic aspects of one type of interaction, the quote, and draw conclusions on how these may support discussion, signal user status, mark relationships between users, and characterize the discussion forum as a community. One interesting implication is that discussion platforms may not need to introduce new features for supporting social signals, and conversely social networks may better integrate discussion by enhancing its content-agnostic qualities. Finally, I demonstrate how content-agnostic information reveals user behavior. I focus specifically on trolls, malicious users that disrupt communities through deceptive or manipulative actions. In fact, the language of trolls blends in with that of civil users in heated discussions, which makes collecting irrefutable evidence of trolling difficult even for human moderators. Nonetheless, I show that a combination of content-agnostic and linguistic features sets apart discussions that will eventually be trolled, and reactions to trolling posts. This provides evidence of how content-agnostic information can offer a point of view on user behavior that is at the same time different from, and complementary to, that offered by the actual content of the contribution. Popular up and coming platforms, such as Snapchat, Tumblr, or Yik Yak, are increasingly abandoning persistent, threaded, text-based discussion, in favor of ephemeral, loosely structured, mixed-media content. Although the results of this dissertation are mostly drawn from discussion forums, its research frame and methods should apply directly to these other venues, and to a broad range of communication paradigms. Also, this is but a preliminary step towards a fuller understanding of what additional cues can or should complement content to overcome the limitations of computer-mediated communication