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The UDSpace Institutional Repository collects and disseminates research material from the University of Delaware.
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Recent Submissions
Motors and Dampers: The Energetic Tradeoffs in the Shod Foot With Increasing Walking Velocity
(Journal of Foot and Ankle Research, 2025-11-11) Henderson, Adrienne; Bruening, Dustin; Arch, Elisa
Background
The dual influences of velocity and footwear on ankle-foot energetics are particularly relevant for clinical populations who rely on footwear during ambulation. Although walking velocity influences energetic demands of foot structures, footwear may modify these relationships by restricting joint motion. This study aimed to characterize ankle-foot energetics while participants walked at a wide range of velocities while wearing supportive shoes.
Methods
Eighteen healthy participants walked at four height-normalized velocities (0.4–1.0 statures/second) in supportive footwear while kinematic and kinetic data were collected. Ankle, midtarsal, and metatarsophalangeal (MTP) work was quantified and compared using repeated-measures ANOVAs with Holm pairwise tests.
Results
MTP positive and negative work increased with shod walking velocity, though negative work increased substantially more than positive work. Midtarsal positive work also increased while maintaining minimal negative work across all velocities. Ankle positive work significantly increased with velocity accompanied by small but significant increases in negative work.
Conclusions
At all velocities, the MTP joint functioned as a mechanical damper and its damping characteristics became more pronounced as velocity increased. The midtarsal joint functioned as a strut, with a small motor role which became more prominent as velocity increased. The ankle had mixed roles, primarily between strut and spring, with a small damper/motor role that traded off with velocity (less damper more motor as velocity increased). The presence of supportive footwear attenuated positive and negative work across velocities when compared to previous barefoot studies, with the largest difference in the midtarsal's negative work, suggesting footwear substantially modifies natural foot mechanics through increasing velocities.
Elevated LDL-C induces T-cell metabolic dysfunction and increasesinflammation and oxidative stress in midlife adults
(Journal of Applied Physiology, 2025-08-08) DeConne, Theodore M.; Ghosh, Arit; Awad, Catherine; Fancher, Ibra S.; Edwards, David G.; Trott, Daniel W.; Martens, Christopher R.
T-cells may contribute to chronic, low-grade, sustained inflammation and oxidative stress commonly observed with aging and chronic disease. T-cell metabolic alterations impact T-cell differentiation, inflammation, and oxidative stress in animal models Low-density lipoprotein cholesterol (LDL-C) has been identified as a novel antigen that activates T-cells via a canonical pathway .However, in humans, little is known about the direct effect of LDL-C on T-cells. Endogenous LDL-C concentration peaks during midlife in humans and may contribute to midlife chronic disease risk by inducing T-cell dysfunction. Thus, this study investigated the effects of exogenous LDL-C exposure on CD4 þ and CD8 þ T-cells from midlife adults. Compared with a physiologically “low” LDL-C concentration, we hypothesized that exposure to “borderline high” LDL-C would induce activation, alter metabolism, and increase mitochondrial reactive oxygen species and inflammatory cytokine production in T-cells from midlife adults. T-cell metabolism was assessed using extracellular flux analysis, and all other outcomes were assessed using flow cytometry. Our findings indicate that exposure to a borderline high concentration of LDL-C induced CD4 þ and CD8 þ T-cell activation, impaired mitochondrial respiration, and increased glycolytic metabolism. Further, we observed exogenous LDL-C exposure induced T-cell differentiation toward activated effector memory and effector memory re-expressing CD45RA subpopulations and increased inflammatory cytokine and mitochondrial reactive oxygen species production. These data suggest that borderline high LDL-C induces T-cell dysfunction that may increase the risk for age-related diseases. Future observational and clinical research should investigate the effects of endogenous LDL-C and other blood lipids on in vivo T-cell function and the implications for disease risk
Low-Q Asymptotic Behavior of the Effective Structure Factor Yields Model-Independent Radius of Interparticle Interaction (Ri)
(ACS Measurement Science Au, 2025-11-07) Edwards, Chelsea E. R.; Leite, Wellington C.; Liu, Yun
Guinier analysis has been extensively used in academic and industrial research settings to obtain the model-independent size of a polymer, protein, or colloid in solution from small-angle scattering data. Using the Guinier model, the radius of gyration (Rg) is extracted from the form factor at low Q. Here, we develop an analogous approach for analyzing the effective structure factor data at low Q to extract a model-independent radius of interaction potential, Ri. Whereas Rg describes how spread out the scattering length density distribution of particles is from their center of mass, Ri is an effective root-mean-square distance that quantifies how far the interparticle correlation deviates from its ideal gas configuration due to interactions. We demonstrate this novel analysis method by applying it to experimental small-angle neutron scattering data on lysozyme protein solutions. We discuss its broad implications for analysis of low-Q asymptotic X-ray and neutron scattering data, where Guinier analysis is traditionally applied.
Stochastic resonance stimulation effect on stability during walking in people with Parkinson disease
(International Biomechanics, 2025-11-06) Alsaqabi, Eman; DiBianca, Stephen; Sansare, Ashwini; Verma, Khushboo; Reimann, Hendrik; Jeka, John
People with Parkinson disease (PwPD) often face challenges with maintaining balance while walking, which can stem from sensory dysfunction. Studies have identified different biomechanical strategies that aid in preserving upright balance control. Stochastic resonance (SR) stimulation delivers sub-threshold electrical noise to enhance the detection capabilities of dysfunctional sensory systems. Yet, the effectiveness of SR in enhancing gait stability in PwPD is undetermined. The purpose of this study was to investigate the effects of SR on balance control during visually perturbed walking in PwPD (NCT06829342).
Fourteen individuals with PD completed the study. We established individualized sensory thresholds for SR stimulation and identified the optimal SR intensity. Following this, the participants walked within a virtually perturbed environment. Center of mass (CoM) excursion, foot placement, and ankle roll responses were assessed bilaterally.
Peak CoM excursion showed a significant increase, indicating reduced stability, with the SR condition compared to no-SR at the more affected side. Outcome measures related to balance control mechanisms were insignificant.
With SR, PwPD were driven by the induced fall with more sway and without significant alterations in balance strategies, which might be due to adding more noise to sensory processing and misidentifying the more affected side.
Simultaneous population genomics of hosts and their parasites with selective whole genome amplification
(Parasites & Vectors, 2025-11-05) Ellis, Vincenzo A.; Theodosopoulos, Angela; Sharma, Ishika; Bardil, Amélie; Stjernman, Martin; Hellgren, Olof
Background Generating parasite genomes is challenging when little of the DNA in infected host tissue is from the parasite. We used selective whole genome amplification (SWGA) to generate genomic data from wildlife samples of the avian haemosporidian Haemoproteus majoris (lineage PARUS1) and its host, the blue tit (Cyanistes caeruleus). Methods We used SWGA to amplify the parasite DNA in nine avian blood samples collected between 1996 and 2021, and subsequently performed short-read sequencing and bioinformatically separated the host and parasite reads in each sample. Results SWGA increased the percentage of parasite reads significantly. Sequencing to a depth of about 56 million reads (forward and reverse) per sample resulted on average (± standard error [SE]) in 11.3X ± 1.85 for the host genome and 1.17X ± 0.446 mean depth of coverage for the host and parasite, respectively, after SWGA. Furthermore, about 74% of the host genome (genome size approx. 1.2 Gb) and 33% of the parasite genome (approx. 23.9 Mb) had at least 1X coverage on average; two samples had 1X coverage of approximately 60% of the parasite genome. Parasite sequencing success was positively correlated with parasitemia. When comparing the parasite sequences in the four best samples, we identified 9895 sites (minimum 5X coverage) that varied among the infections. When filtering the full dataset to at least six samples per variant, we identified 14,512,339 and 7068 sites that varied among samples in the host and parasite populations, respectively, revealing variation among samples and years. Conclusions SWGA facilitates dual host-parasite population genomics in this system and will greatly expand our understanding of host-parasite interactions over space and time.