Northeast Climate Science Center

ScholarWorks@UMass Amherst
Not a member yet
    109958 research outputs found

    How likely is it that omitted variable bias will overturn your results?

    Full text link
    Building on a recently developed methodology for sensitivity analysis that parametrizes omitted variable bias in terms of partial R-Squared measures, I propose a simple statistic to capture the severity of omitted variable bias in any observational study: the probability of omitted variable bias overturning the reported result. The central element of my proposal is formal covariate benchmarking, whereby researchers choose an observed regressor (or a group of observed regressors) to benchmark the relative strength of association of the omitted regressor with the outcome variable and with the treatment variable. These relative strengths of association function as the two sensitivity parameters of the analysis. By allowing these sensitivity parameters to take all permissible values, we get the most conservative estimate of the probability that omitted variable bias can overturn the reported results. By using absolute and relative limits on the maximum values of the sensitivity parameters based on institutional knowledge or other details of the particular study, a researcher can generate less conservative estimates of that probability. For empirical studies with relatively large number of regressors and sample sizes, I suggest bounds for the sensitivity parameters based on simulation studies. I illustrate the methodology using an empirical example that studies the effect of exposure to violence on attitudes towards peace

    Separable graph Hamiltonian network: A graph deep learning model for lattice systems

    Full text link
    Addressing the challenges posed by nonlinear lattice models, which are vital across diverse scientific disciplines, we present a new deep learning approach that harnesses the power of graph neural networks. By representing the lattice system as a graph and leveraging the graph structures to identify complex nonlinear relationships, we have developed a flexible solution that outperforms traditional techniques. Our model not only offers precise trajectory predictions and energy conservation properties by incorporating separable Hamiltonians but also proves superior to existing top-tier models when tested on classic nonlinear oscillator lattice problems: a mixed Fermi-Pasta-Ulam Klein-Gordon, a Klein-Gordon system with long-range interactions, and a twodimensional Frenkel-Kontorova, highlighting its potential for wide-reaching applications

    TIBETAN INTERNATIONAL STUDENTS AND RETURNEES: EXPERIENCES, IDENTITIES, AND TRANSNATIONALISM

    No full text
    This dissertation situates current Tibetan international students and returnees in the unprecedented changing phenomenon of the global flow of people, knowledge, and culture within the trend of the higher education internationalization. Informed by the discourse of transnationalism, this research explores lived experiences and identity of Tibetan international students and returnees during their international education mobility journeys, it questions how their academic and social experiences in the U.S. are intertwined with their everyday negotiations of identity, network, and culture. In addition, the study examines how, why and to what extent have Tibetan international students’ overseas educational experiences impacted the personal, professional development and identities of those who returned to work in China/Tibet. Adopting a qualitative thematic analysis approach, the study recruits sixty-five Tibetan international students and returnees who are either currently studying at the U.S. universities or graduated from such higher education institutions. It collects data through interviews, surveys, texts, documents, and videos from Chinese social medias, in addition, through research memos. Data collection is centered around participants whose lived academic and social experiences, as well as cultural practices and perceptions on identity. Findings demonstrate significance of phayul, a Tibetan word for homeland, as an abstract transnational social field in Tibetan international students’ education mobility and its impact on their lived experience abroad. Tibetan international students bring their cultural practices and Buddhist values to their new transnational space, such practices including burning incense and chanting mantras. Such movements of cultures across borders are ways for the participants to reconnect with their homeland and rework their identity. In return, their everyday cultural practices, and rituals in the transnational space, reshape their identity

    QUANTUM CHAOS, INTEGRABILITY, AND HYDRODYNAMICS IN NONEQUILIBRIUM QUANTUM MATTER

    Full text link
    It is well-known that the Hilbert space of a quantum many-body system grows exponentially with the number of particles in the system. Drive the system out of equilibrium so that the degrees of freedom are now dynamic and the result is an extremely complicated problem. With that comes a vast landscape of new physics, which we are just recently starting to explore. In this proposal, we study the dynam- ics of two paradigmatic classes of quantum many-body systems: quantum chaotic and integrable systems. We leverage certain tools commonly employed in equilibrium many-body physics, as well as others tailored to the realm of non-equilibrium scenar- ios, in order to address various problems within this evolving field. Our contributions are the following: Inspired by random matrix theory and random unitary circuits subject to projective measurements, we first uncover a novel phase transition in a model of random tensor networks separating an area-law from a logarithmic-law in the scaling of entanglement entropy of a many-body wavefunction. Next, we study transport in the Rule 54 cellular automaton, a paradigmatic integrable model displaying just two species of solitons of different chiralities. Our contribution here is a sound numerical verification of some of the formulas for transport coefficients recently derived within a generalized hydrodynamic approach valid for integrable systems. Using the equations of generalized hydrodynamics as a starting point we then propose a new phenomenological scheme based on a relaxation-time approximation widely used in kinetics, but fundamentally different, to study the experimentally relevant regime where only a few conservation laws are present. We then aim at uncovering the hydrodynamics of integrability-breaking starting from fully microscopic dynamics. To do so we study a noisy version of the Rule 54 model and of the hard-rod gas, where the source of noise in both models is backscattering of solitons. We find that these models of integrability-breaking are atypical in that in the former relaxation occurs at long time scales owing to the presence of kinetic constraints, and the latter displays singular transport signatures as a result of infinitely many conserved charges despite the model being nonintegrable. Finally, we conclude by studying operator spreading in both integrable and chaotic quantum chains. Using hydrodynamics and tensor net- work simulations we find distinctive signatures of these two classes of models when looking at their operator front

    Theory of Service: The User Perspective

    Full text link
    For development of the theory of service, the focus was on the constructs of service. The theory is expanded to encompass the various business models of service and the service encounter including but not limited to guest satisfaction, service quality, service and technology, service system design, and customer relationship management. The theory began with the observed differences in different service settings, the emergence of technology and defining the service experience across multiple sectors. Further consideration is given to the aspects of the service transaction and what constitutes service, where a labor component of a firm’s product has been transferred to the customer. Lastly, self-service and automation are considered in the context of the user experience. Implications for industry application are discussed

    The Art and Science of Promptgramming

    Full text link
    In this paper, I explore the emerging field of Promptgramming, a technique essential for harnessing the potential of generative AI. Promptgramming involves crafting strategic prompts to guide AI systems, a skill that becomes increasingly crucial as AI tools become more integrated into our daily technological landscape, particularly in education. I discuss the core principles and best practices of Promptgramming, emphasizing its importance in creating personalized and engaging educational content. Additionally, I address the ethical considerations and challenges that arise with the integration of AI in education, such as academic integrity, bias, privacy, and misinformation. Looking towards the future, I highlight the integration of AI into mainstream operating systems and its implications for society, calling for a focus on AI literacy and ethical usage. The paper synthesizes these concepts, underscoring the necessity for educators and society to adeptly navigate the emerging landscape of AI, ensuring its responsible and effective application in enhancing learning experiences and societal development

    A Conversation on Using AI to Create Interactive Open Educational Resources

    No full text
    During this session we will delve into the transformative potential of AI in enhancing educational content and pedagogy. Our discussion will begin with a brief introduction to AI technologies and their relevance to open educational resources, setting the stage for an engaging journey into the future of education. To ensure an interactive and participatory experience, we will employ real-time polls to gauge audience opinions on key topics and challenges. We will also encourage the use of a dedicated Twitter hashtag to extend our conversation beyond the physical confines of the conference room, enabling a dynamic exchange of ideas and best practices in real time. This session is designed for faculty, instructional designers, library staff, and technology specialists interested in the intersection of AI and education

    Open Resources, Open Minds: Building Global Communities with the World Librarians

    No full text
    The first 15 minutes of the presentation will feature a brief overview of the history of world librarians, our mission to deliver information as requested by our global partners who most commonly reside in the Global South, without bias or gatekeeping, and acknowledging the need for that service as members of the Global North. In the first part of the presentation, we’ll also be covering a brief overview of our technical workflow, and how we are able to support this type of information sharing with limited internet access. In the remaining 20 minutes of our presentation time, faculty advisors will pose questions to our student panel about their experiences, ranging from notable requests they’ve received (responses include questions about making toys out of trash, female genital mutilation, and the Bible) to how their involvement in the club has impacted them in their respective fields. A common theme will be centered around the role of Open in everything from their own reliance on the internet, their education, and global information sharing. Because we hope to expand this model to other campuses, a survey will be shared with attendees to gauge interest in doing so. A final 10 minutes will be devoted to answering questions from the audience

    Statewide Student Course Materials Surveys: Lessons from a Unique Partnership

    No full text
    As the end of grant funding neared, Affordable Learning PA (ALPA) sought to allocate resources to a statewide course materials survey. ALPA lacked the personnel and expertise to replicate surveys conducted in Florida and Virginia. They are labor intensive, especially data analysis and reporting. ALPA instead chose a partner with the necessary survey expertise. Given its prior OER survey experience, ALPA identified Bay View Analytics to assist with development and administration. Despite not having conducted a state-wide student survey such as this, Bay View saw this work as valuable and agreed to partner with ALPA. Panelists will discuss the evolution of their partnership in exploring their mutual interest in conducting a statewide student course materials survey. Special attention will be paid to barriers that arose and how the two partners worked collaboratively to overcome them. Attendees will learn how the survey was based on existing statewide surveys and modified for the current application. Panelists will share information and findings from the survey results in discussing the efficacy of the survey efforts, with comparisons to what other statewide surveys have found. They will discuss how similar/different the findings are and whether there is an expectation that future statewide course materials surveys would deviate little or a great deal from those findings of prior statewide surveys. Panelists will conclude with a set of recommendations for other state OER associations that will be considering conducting their own statewide survey. Audience engagement will be achieved through interactive polling and live chat activity

    Collaborative Caching and Computation Offloading for Intelligent Transportation Systems enabled by Satellite-Airborne-Terrestrial Networks

    No full text
    Intelligent Transportation Systems (ITS) face important challenges in remote areas due to the lack of terrestrial infrastructure and low traffic flow, complicating the update of fundamental data for different applications. The integration of Geosynchronous Orbit (GEO) satellites, Low Earth Orbit (LEO) satellites, and High Altitude Platforms (HAP) in ITS offers a unique and effective solution to address these challenges. In this work, we design an ITS-enabled satellite-airborne-terrestrial network in which HAPs and RSUs are organized into clusters and cooperate for caching and computing. In particular, we study caching, bandwidth allocation, and computation offloading strategies to minimize latency and energy consumption. To solve this problem, a multi-agent cluster-based attention weight algorithm with federated update (Cluster-FCMC-Att) is proposed. The abbreviation FCMC stands for federated caching, matching, and computing. Federated learning supports information exchange between RSUs, and the attention mechanism assists HAPs in computing resource allocation and caching decisions. Our extensive numerical results show that our approach achieves fast and stable convergence, significantly decreases the delay and energy consumption, and computes about six times more data than existing schemes

    31,896

    full texts

    124,888

    metadata records
    Updated in last 30 days.
    ScholarWorks@UMass Amherst is based in United States
    Access Repository Dashboard
    Do you manage Open Research Online? Become a CORE Member to access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard! 👇