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A posteriori error computation in finite element method for initial value problems
No full textIn space-time coupled and in space-time decoupled finite element methods of obtaining solutions of initial value problems, determination of the errors (a-posteriori computations) in the computed solution during the evolution is essential: 1) to ensure that the computed solution is meaningful, 2) if the errors are higher than the accepted threshold, then to be able to design an adaptive process based on these errors to improve the accuracy of the solution.
In this paper we present "a-posteriori" error computation methodologies, computational infrastrature and model problem studies for the finite element solutions of initial value problems (IVPs) obtained using space-time coupled (STC) and space-time decoupled (STDC) finite element methods. In initial value problems, the physics require simultaneous dependence of solutions in space and time. Solutions of initial value problems are evolutions i.e. the solution changes at spatial locations as time elapses. The most efficient way to calculate such solution is to consider increments of time Δt starting with initial condition at time t0 or zero and compute evolution for t0 ≤t ≤Δt. Upon obtaining a converged solution for this increment of time, we can then march to t0+Δt ≤ t ≤ 2Δt and so on.
In space-time decoupled methods, we consider a spatial discretization over the integral form of the initial value problem in space over the discretization. The local approximations consist of approximation dependent on spatial coordinates and the degrees of freedom dependent on time. Using the local approximations integrals over elements are evaluated in space, thereby eliminating spatial coordinates and leaving only time variations of the degrees of freedom. Upon assembly, we obtain a system of ordinary differential equations in time that need to be integrated to obtain solution for dofs and their time derivatives. Thus, in this approach, called space-time decoupled methods, treatment in space and time is not simultaneous as required by the initial value problem.
In both approaches, the solution is obtained for an increment of time. Thus, it is beneficial to consider "a-posteriori" error computations for each increment of time for space-time coupled as well as space-time decoupled finite element processes. In this paper we present details of the mathematical and computational infrastructure for a-posteriori error computations for space-time coupled as well as space-time decoupled methodologies for the solutions of initial value problems. This is followed by model problem studies to illustrate various aspects of a-posteriori error computation methodologies for the solutions of initial value problems obtained from space-time coupled and space-time decoupled finite element methods. Summary, the work presented in this paper and some conclusion drawn from it are presented in the last section of the paper
Phenotypic Variation among Populations of a Dominant Species from Remnant and Restored Prairies
No full textThese are the slides from a presentation given at the Ecological Society of America (ESA) held in Baltimore, Maryland on 08/12/2025.Common garden experiments can reveal the amount of phenotypic variation within and among populations of species. This information can be used to inform restoration. Restoration guidelines often recommend sourcing seeds locally to preserve adaptations to specific environmental conditions. Sourcing seed locally still presents decisions such as whether to collect seed from remnant or restored populations and whether amending soil with mutualists benefits establishment and growth species used in restorations. There are many restored grasslands in the tallgrass prairie region, along with prairies that have never been cultivated. To inform whether remnant or restored populations contain different phenotypes of a dominant species, we established a common garden of Andropogon gerardii (big bluestem) with seeds collected from four remnant and four restored prairies co-located in the same climate region. Seeds were propagated in a greenhouse before being planted in the common garden. An arbuscular mycorrhizal fungi (AMF) treatment was added to half of the plants from each population when planted. Plant height and phenology were measured weekly, and biomass of each plant was collected at the end of the season. Final height differed among the eight populations and between remnant and restored sources of plant material. Final plant height was not affected by the AMF treatment. More plants flowered sooner from restored than remnant populations. Biomass varied among the eight populations, but there was no difference between average biomass of remnant and restored populations, nor was there an effect of adding AMF. There was more variation in biomass among grasses sourced from remnant populations, whereas there were no differences in biomass among plants from the restored populations. These findings indicate that there can be significant phenotypic variation among populations within a climate region and that variation is greater in big bluestem among natural vs. restored populations. Understanding the extent of phenotypic variation among populations in area can inform local seed-sourcing strategies to create heterogeneity and the maximize adaptive potential of restorations
Hybrid zone analysis with the R package triangulaR: lessons learned from simulations and empirical datasets
No full textThese are the slides from a presentation given at the American Society of Ornithology held in St. Louis, Missouri on 08/13/2025.Describing patterns of genetic variation across populations and species is a fundamental goal of molecular phylogeography and population genetics. Within those fields, studies that use molecular data to investigate hybridization between two or more species present an opportunity to describe the evolutionary processes that contribute to or break down species boundaries, providing critical insight into the speciation process. Triangle plots, which use genetic data to show the relationship between hybrid index and interclass heterozygosity, can distinguish among multiple hybrid classes (e.g., F1s, F2s, backcrosses). They are also an effective method for distinguishing between continuous variation in a single taxon and hybridization between two taxa. Further, they can provide insight into the details of hybrid zone dynamics by describing the distribution of hybrid classes across the hybrid zone. Here, we introduce triangulaR, an R package for identifying ancestry-informative markers (AIMs) from genetic datasets, calculating hybrid index and interclass heterozygosity, and visualizing triangle plots. We validate our methods using simulations of genetic data from a hybrid zone of two parental groups at various levels of divergence. We explore how parental group sample sizes and the allele frequency difference threshold for AIM identification influence the accuracy and precision of hybrid index and interclass heterozygosity estimates. We contextualize interpretation of triangle plots by describing theoretical expectations under Hardy-Weinberg Equilibrium and provide recommendations for best practices for building triangle plots. Finally, we demonstrate the utility of triangulaR using case studies from empirical datasets
Parental Migration and the Well-being of Children Left Behind in Harare, Zimbabwe (Dataset)
No full textThis study investigates the effects of parental migration on the well-being of children left behind in Zimbabwe using a mixed-methods approach combining survey data and in-depth interviews. It investigates how migration reshapes parental dynamics and impacts children’s physical and mental health, education, financial stability, communication, and protection. A unique six-dimensional well-being index guides the analysis, encompassing physical health, psychological health, education, financial conditions, access to communication, and protection. Quantitative data offers a broad statistical view of migration’s impact across these dimensions, while qualitative insights from the interviews with caregivers offer a nuanced understanding of the lived experiences and personal perceptions within each dimension. The multi-dimensional index serves as an inclusive framework for assessing the complex consequences of parental migration, permitting a more well-rounded evaluation of the well-being of left-behind children. By combining both quantitative and qualitative approaches, this research aims to contribute refined insights into the multifaceted dynamics surrounding the impact of parental migration on the well-being of children in Zimbabwe. The findings aim to inform targeted interventions and policies that address the specific needs identified within each dimension, fostering a more holistic support system for children left behind in the context of migration
Error-Sensitive Dynamic Calibration for Online Optimization with Switching Cost
No full textThese are the slides from a presentation given at the Allerton conference held at the University of Illinois Urbana Champagne on 09/19/2025.Neural networks (NNs) have achieved state-of-the-art performance in a wide range of applications; however, their deployment in online settings often exposes a lack of robustness due to various dynamic and uncertain conditions. In contrast, traditional online algorithms offer formal robustness guarantees, yet generally do not attain the predictive accuracy of modern neural network models. To address this trade-off, we propose a novel neural network architecture that incorporates a dynamic calibration layer, designed to enhance robustness in online environments without sacrificing predictive performance.
The proposed dynamic calibration layer consists of a differentiable optimization component that adjusts the NN output in real time, enabling end-to-end training via standard backpropagation. We provide theoretical analysis establishing performance bounds relative to an offline optimal benchmark. Next, we leverage these bounds to constrain the function class used for dynamic calibration, ensuring both practical feasibility and theoretical soundness.
Empirical evaluation is conducted on a real-world case study involving data center energy management. Comparative results against existing online and hybrid approaches demonstrate that our architecture consistently outperforms baseline methods, both in terms of average performance and robustness measured in terms of competitive ratio
QUIXOTE IN THE CLASSROOM The Rise and Fall of KU’s Integrated Humanities Program
No full textSubmitted to the Department of History of the University of Kansas in partial fulfillment of the requirements for departmental honorsThe University of Kansas in the 1970’s played host to a singular experiment in the world of higher education, the Integrated Humanities Program (IHP). The IHP promoted a unique style of learning, a study of the Great Books founded upon the “poetical mode”. Students in the program had mandatory stargazing hours, memorized poetry, and were forbidden from taking notes in class. Alongside the uniqueness of the program’s educational style was the unique fervor with which people protested it, and the IHP would last only nine years, from 1970-1979. Despite its relatively short lifespan, the IHP has left a long memory in the vibrant Classical Education and Catholic intellectual communities. Few books have been written about the IHP, and the few that have are from graduates of, or men associated with, the program. My research into the IHP interrogates the origins and development of this novel educational movement, discourses of academic independence and free inquiry, and how IHP reveals the relationship between the humanities, education, and asking questions and finding answers old and new at a time of great transformation
Fiscal Stimulus and Housing Booms: Evidence from the 2003 Tax Cuts
No full textThese are> the slides from a presentation given at the 2025 Financial Management Association Annual Meeting held in Vancouver, Canada on 10/23/2025.This paper examines how the Bush-era tax cuts contributed to the U.S. housing boom that preceded the Great Recession. We focus on the 2003 reductions in dividend and capital gains tax rates and use a difference-in-differences design that exploits cross-county variation in stock market exposure to identify the effects. Counties more exposed to the tax cuts experienced significantly faster house price growth after 2003 and greater housing activity, including home purchases and improvements---particularly for investment properties. We uncover a novel portfolio rebalancing channel linking equity payouts to housing demand, suggesting that the surge in corporate distributions following the tax cuts amplified their impact on house prices. Complementary evidence indicates that the concurrent reduction in regular income taxes also stimulated housing demand. Taken together, the findings imply that the Bush-era tax cuts played a meaningful role in fueling the early-2000s housing boom and highlight housing as an important transmission channel of fiscal stimulus
Reorganizing bonds: A qualitative exploration of the bereavement experience of the adult only children who lost their parent
No full textThese are the slides from a presentation given at Society for Social Work and Research 29th Annual Conference on 01/16/2025.Background and Purpose:
Losing parents is one of the most traumatic life events, exerting profound effects on the physical, psychological, and spiritual well-being of adult children. Despite extensive literature on bereavement experiences, the unique challenges faced by China's only-child generation following parental loss remain insufficiently explored. Since its implementation in 1970s, China's one-child policy has shaped a unique generation of individuals who have been raised and grown up under its influence. Up to date, a significant portion of this population has experienced parental loss. This study seeks to delve into the bereavement experiences of only-child populations who have lost their parent(s) within the past five years.
Methods:
Qualitative methods were employed. Participants were required to be aged 18 or older, have suffered a non-accidental parent loss between 2018 and 2023, and have provided end-of-life care for at least one month. Recruitment flyers were posted on four major social media in China from November 2023 to March 2024. Eligible participants were provided with consent forms. One-on-one interviews were conducted either online through Tencent Meeting or WeChat, or in person. Interviews were recorded and transcribed verbatim. Interview transcripts were analyzed using ATLAS.ti software, applying thematic analysis for qualitative data. The study protocol was approved by the Institutional Review Board at Renmin University of China.
Results:
A total of 15 eligible participants were included in the study. Most of the participants were female (73.3%), with an age range of 21 to 43, and half of them served as the end-of-life caregivers of their fathers (53.3%). From a Continuing Bonds perspective, three phases emerged from data analysis: (1) Deconstructing bonds: feelings of loss, owedness, and loneliness; (2) Reconstructing bonds: connecting with decedents through spiritual rites, memories, and new recognitions; (3) Reorganizing bonds: internalization, maturity, and resilience. In the deconstruction phase, the bereaved only-children described senses of loss, loneliness, and owedness for digesting the death of their parents and the physical disconnections with the deceased. Subsequently, the bereaved only-children involved connections with the deceased such as holding spiritual rites, recalling memories, and gaining new recognition of their parents. For the reorganizing phase, participants reported that they inherited their parents’ qualities and found personal growth such as maturity and resilience. These findings illustrate an adaptive process of maintaining connections with deceased parents. Three phases might overlap and be ongoing simultaneously.
Conclusions and Implications:
The study's findings emphasize the need to understand the bereavement experiences of adult only-children through the continuing bonds with their deceased parents and the adaptive process from deconstruction to reorganization. The results contribute to the social work literature and offer insights into the bereavement experiences of the upcoming millions of only-child individuals. Social workers can utilize these insights to provide psychosocial support and foster supportive communities, thereby alleviating loneliness and social isolation during the deconstruction phase and enhancing meaning-making during the reconstruction and reorganization phase
Estrogen Depletion Effects on Lipid Homeostasis and Myelination
No full textThese are the slides from a presentation given at Pittcon 2025 conference and expo on 03/04/2025.Nearly 75% of multiple sclerosis patients are female and have symptoms that improve during pregnancy and worsen during post-menopause, which correlates with changes in estrogen levels within the body.1,2 Studies have shown that the beneficial effects of estrogen on myelination may be attributed to lipid changes in the CNS.1,3 Menopause is associated with worsening symptoms in MS and a decrease in glucose metabolism in the brain which leads to the breakdown of myelin lipids.3 However, the effect of menopause on demyelination and the regulation of myelin lipid pathways has yet to be fully investigated. Our objective is to determine how estrogen loss affects CNS lipid metabolism during demyelination and remyelination. To achieve this goal, we are using the iCKO-Myrf (myelin regulatory factor) mouse strain as a model of demyelination, in which tamoxifen is used to induce ablation of Myrf and initiate demyelination. To mimic menopause, we perform ovariectomies to deplete estrogen prior to inducing demyelination. The experimental groups include ovariectomized females, sham surgery females, control females and control males. Rotarod and horizontal ladder tests are used to monitor motor disability and recovery of mice. Our preliminary results suggest that estrogen depletion accelerates the onset of motor disability after demyelination. Brain and spinal cord tissue will be collected from experimental mice at weeks 12 and 24 post-tamoxifen injection, which represents peak demyelination and remyelination recovery. Myelin and cellular markers of myelin will be analyzed by BlackGold staining, electron microscopy, and immunofluorescence. Lipidomic analysis will be performed using tandem mass spectrometry to measure how phosphatidylcholines, sphingomyelins, phosphatidylserines, and phosphatidylethanolamines are altered with estrogen depletion in demyelination. These studies will define how estrogen loss in the iCKO- Myrf mouse model affects remyelination and CNS lipid metabolism during demyelination. These experiments will enable us to identify mechanisms that mediate the connection between menopause and multiple sclerosis.
References:
1. Rankin, K.; Mei, F.; Kim, K.; Shen, Y.; Mayoral, S.; Desponts, C.; Lorrain, D.; Green, A.; Baranzini, S.; Chan, J.; Bove, R., J. Neurosci. Res., 2019, 39 (12), 2184.
2. Bove, R.; Okai, A.; Houtchens, M.; Elias-Hamp, B.; Lugaresi, A.; Hellwig, K.; Kubala, Havrdová, E., Front. Neurol., 2021, 12, 554375.
3. Voskuhl, R.; Itoh, N.; Tassoni, A.; Matsukawa, M.; Ren, E.; Tse, V.; Jang, E.; Suen, T.; Itoh, Y., PNAS, 2019, 116 (20), 10130
Evaluation of the Thermal Resilience of Residential Buildings with PCM Enhanced Envelope Under Different Climate Zone
No full textThese are the slides from a presentation given at 2025 ASHRAE winter meeting on 02/10/2025.The increasing frequency of heat wave events has significantly impacted residential buildings and the health of their occupants. Utilizing thermal storage to mitigate overheating presents a promising solution. To investigate this, we comprehensively assess the energy and thermal resilience performance of residential buildings with phase change material (PCM)-enhanced building envelopes in normal weather conditions and during heat wave events across different climate zones. The results show that integrating PCM-enhanced building envelopes can achieve 2.1-36.5% of energy saving for different climate zones. It can also significantly improve the thermal resilience in terms of the KPIs of indoor overheating degree (IOD), ambient warmness degree (AWD) and overheating escalation factor (OEF) during heat wave events with or without power outages for most of the climate zones. Further enhancement of thermal resilience during heat wave events with power outages has been achieved by combining natural ventilation at night with the PCM-enhanced building envelopes