25 research outputs found

    Does Experimental Anterior Knee Pain Alter Effects of Running on Femoral Articular Cartilage Thickness and Volume? A Pilot Study

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    Anterior knee pain is a common problem for runners that often alters running biomechanics. It is unclear how/if changes in running biomechanics due to anterior knee pain affect knee articular cartilage health. PURPOSE: To determine if experimental anterior knee pain during running acutely alters deformation in femoral articular cartilage due to running. METHODS: 10 runners completed three sessions that each in- volved a 60-min treadmill run: a control, sham, and pain session. Experimental anterior knee pain was in- duced during the pain session via a continuous infusion of hypertonic saline into the infrapatellar fat pad. The sham and control sessions involved a continuous infusion of physiological saline and no infusion, re- spectively. Before and after running, magnetic resonance imaging was used to quantify femoral articular cartilage thickness and volume. A repeated measures ANOVA was used to evaluate effects of running with experimental anterior knee pain on perceived knee pain and femoral articular cartilage deformation (α = 0.05). RESULTS: Perceived anterior knee pain was significantly greater during the pain session relative to the control and sham sessions (p p = 0.05), and more due to the pain session run (-57.7 ± 157.4 mm3) than the control session run (p = 0.09). No significant effects of session were observed for medial or lateral thickness or lateral volume. CONCLUSION: Articular cartilage response to running (medial femoral volume) was different for the pain and sham sessions relative to the control session. The physiological and hypertonic saline infusions appeared to alter medial knee articular cartilage response to running. These changes might be due to altered biomechanics due to the infusions. Additional research is needed to clarify the cause of the altered response to running

    Dual-gated graphene devices for near-field nano-imaging

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    Graphene-based heterostructures display a variety of phenomena that are strongly tunable by electrostatic local gates. Monolayer graphene (MLG) exhibits tunable surface plasmon polaritons, as revealed by scanning nano-infrared experiments. In bilayer graphene (BLG), an electronic gap is induced by a perpendicular displacement field. Gapped BLG is predicted to display unusual effects such as plasmon amplification and domain wall plasmons with significantly larger lifetime than MLG. Furthermore, a variety of correlated electronic phases highly sensitive to displacement fields have been observed in twisted graphene structures. However, applying perpendicular displacement fields in nano-infrared experiments has only recently become possible (Ref. 1). In this work, we fully characterize two approaches to realizing nano-optics compatible top-gates: bilayer MoS2\text{MoS}_2 and MLG. We perform nano-infrared imaging on both types of structures and evaluate their strengths and weaknesses. Our work paves the way for comprehensive near-field experiments of correlated phenomena and plasmonic effects in graphene-based heterostructures

    Community-based organization perspectives on participating in state-wide community canvassing program aimed to reduce COVID-19 vaccine disparities in California

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    Background: Inequities in COVID-19 vaccine accessibility and reliable COVID-related information disproportionately affected marginalized racial and ethnic communities in the U.S. The Get Out the Vaccine (GOTVax) program, an innovative statewide government-funded COVID-19 vaccine canvassing program in California, aimed to reduce structural barriers to COVID-19 vaccination in high-risk communities with low vaccination rates. GOTVax consisted of a community-academic-government partnership with 34 local trusted community-based organizations’ (CBOs) to conduct COVID-19 vaccine outreach, education, and vaccine registration. The purpose of this qualitative evaluation study was to explore the barriers and facilitators of using local CBOs to deploy a geographically, racially, and ethnically diverse state-wide COVID-19 vaccine outreach program. Methods: Semi-structured online interviews were conducted with participating GOTVax CBO leaders from November 2021 to January 2022. Transcripts were analyzed using reflexive thematic analysis. Results: Thirty-one of 34 CBOs participated (91% response rate). Identified themes encompassed both facilitators and barriers to program participation. Key facilitators included leveraging trust through recognized entities; promoting empathetic, tailored outreach; and flexibility of milestone-based CBO funding contracts for rapid program implementation. Barriers included navigating community sociopolitical, geographic, and cultural factors; managing canvassers’ safety; desiring metrics for self-evaluation of outreach success; mitigating canvassing technology challenges; and concerns of program infrastructure initially limiting outreach. CBOs problem-solved barriers with academic and government partners. Conclusions: Between May and December 2021, the GOTVax program reached over 2 million California residents and registered over 60,000 residents for COVID-19 vaccination. Public health campaigns may improve benefits from leveraging the expertise of community-trusted CBOs and universities by providing flexible infrastructure and funding, allowing CBOs to seamlessly tailor outreach most applicable to local minoritized communities

    Moiré metrology of energy landscapes in van der Waals heterostructures

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    The emerging field of twistronics, which harnesses the twist angle between two-dimensional materials, represents a promising route for the design of quantum materials, as the twist-angle-induced superlattices offer means to control topology and strong correlations. At the small twist limit, and particularly under strain, as atomic relaxation prevails, the emergent moiré superlattice encodes elusive insights into the local interlayer interaction. Here we introduce moiré metrology as a combined experiment-theory framework to probe the stacking energy landscape of bilayer structures at the 0.1 meV/atom scale, outperforming the gold-standard of quantum chemistry. Through studying the shapes of moiré domains with numerous nano-imaging techniques, and correlating with multi-scale modelling, we assess and refine first-principle models for the interlayer interaction. We document the prowess of moiré metrology for three representative twisted systems: bilayer graphene, double bilayer graphene and H-stacked MoSe2/WSe2. Moiré metrology establishes sought after experimental benchmarks for interlayer interaction, thus enabling accurate modelling of twisted multilayers

    Pregnancy, Microchimerism, and the Maternal Grandmother

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    A WOMAN OF REPRODUCTIVE AGE OFTEN HARBORS A SMALL NUMBER OF FOREIGN CELLS, REFERRED TO AS MICROCHIMERISM: a preexisting population of cells acquired during fetal life from her own mother, and newly acquired populations from her pregnancies. An intriguing question is whether the population of cells from her own mother can influence either maternal health during pregnancy and/or the next generation (grandchildren).Microchimerism from a woman's (i.e. proband's) own mother (mother-of-the-proband, MP) was studied in peripheral blood samples from women followed longitudinally during pregnancy who were confirmed to have uncomplicated obstetric outcomes. Women with preeclampsia were studied at the time of diagnosis and comparison made to women with healthy pregnancies matched for parity and gestational age. Participants and family members were HLA-genotyped for DRB1, DQA1, and DQB1 loci. An HLA polymorphism unique to the woman's mother was identified, and a panel of HLA-specific quantitative PCR assays was employed to identify and quantify microchimerism. Microchimerism from the MP was identified during normal, uncomplicated pregnancy, with a peak concentration in the third trimester. The likelihood of detection increased with advancing gestational age. For each advancing trimester, there was a 12.7-fold increase in the probability of detecting microchimerism relative to the prior trimester, 95% confidence intervals 3.2, 50.3, p<0.001. None of the women with preeclampsia, compared with 30% of matched healthy women, had microchimerism (p = 0.03).These results show that microchimerism from a woman's own mother is detectable in normal pregnancy and diminished in preeclampsia, supporting the previously unexplored hypothesis that MP microchimerism may be a marker reflecting healthy maternal adaptation to pregnancy

    Polariton design and modulation via van der Waals/doped semiconductor heterostructures

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    Abstract Hyperbolic phonon polaritons (HPhPs) can be supported in materials where the real parts of their permittivities along different directions are opposite in sign. HPhPs offer confinements of long-wavelength light to deeply subdiffractional scales, while the evanescent field allows for interactions with substrates, enabling the tuning of HPhPs by altering the underlying materials. Yet, conventionally used noble metal and dielectric substrates restrict the tunability of this approach. To overcome this challenge, here we show that doped semiconductor substrates, e.g., InAs and CdO, enable a significant tuning effect and dynamic modulations. We elucidated HPhP tuning with the InAs plasma frequency in the near-field, with a maximum difference of 8.3 times. Moreover, the system can be dynamically modulated by photo-injecting carriers into the InAs substrate, leading to a wavevector change of ~20%. Overall, the demonstrated hBN/doped semiconductor platform offers significant improvements towards manipulating HPhPs, and potential for engineered and modulated polaritonic systems
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