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Tissue-like Fracture Toughness and Stress–Relaxation Ability in PVA-Agar-Based Hydrogels for Biomedical Applications
No full textSoft tissues exhibit remarkable stretchability, fracture toughness, and stress–relaxation ability. They possess a large water content to support cellular processes. Mimicking such a combination of mechanical and physical properties in hydrogels is important for tissue engineering applications but remains challenging. This work aims to develop a hydrogel that can combine excellent mechanical properties with cellular viability. The research focused on polyvinyl alcohol (PVA)/agar double-network (DN) hydrogels, fabricated by thermal gelation and freeze–thawing methods. Their mechanical properties were characterized through tension, compression, fracture, and stress–relaxation tests, and their cellular viability was measured through cytotoxicity tests. The results show that the PVA/agar DN gels are highly stretchable (\u3e200%) and compressible (\u3e30%) while containing high water content. The incorporation of agar by 6 wt% improved the fracture toughness of hydrogels from 1 to 1.76 kJ/m2. The degree of stress–relaxation, a key indicator of gel viscoelastic properties, improved by roughly 170% with an increase in agar content from 0 to 6 wt%. Cytotoxicity analysis showed that the gels, being physically cross-linked, were able to promote cellular proliferation. This work shows that tough and viscoelastic PVA/agar DN gels are suitable for soft tissue engineering applications, especially cartilage repair
Migration in the Early Chesapeake: Dorchester Co., MD, as a Case Study, 1650–1750
No full textThis article examines the migration patterns that shaped the early settlement of Dorchester County, Maryland. Dorchester County is located on Maryland’s Eastern Shore, an area distinctive in terms of its geography, history, and culture. In U.S. history, migration has generally proceeded from eastern areas to western ones and from northern areas to southern ones, a pattern dating back to the earliest colonial settlements. Settlement in Dorchester County proceeded primarily from east to west and south to north, with additional migration streams coming from the north out of Delaware and from the west out of Somerset County. This gave Dorchester County an unusual historical dynamic because of the different socio-cultural and religious backgrounds and settlement patterns from the regions in which those migrants came. The Eastern Shore’s geography, shaped by an extensive coastline and major riverways, contributed to this settlement pattern, for the Chesapeake Bay region, with its complex network of rivers and streams, forms one of the world’s three largest natural estuaries. In terms of genealogy and family history, this mix of settlers importantly shaped the cultural dynamics of the Eastern Shore, leading to complex family histories that blended different cultural, religious, and linguistic influences. Free European-American settlers dominated migration into early Dorchester, but unfree laborers, including slaves and, early on, white indentured servants, came to Dorchester in substantial numbers along these same routes and made important contributions to the cultural development of Dorchester and surrounding areas. In later years, out-migration from the Eastern Shore took settlers of all backgrounds throughout the growing United States and carried the influence of the Eastern Shore to the south and west as well as into the urban areas of the northeast
Patient-Defined Outcomes in Adults with Hip Dysplasia: What Activities Do Patients Hope to Improve with Treatment?
No full textIntroduction: Patient-reported outcome measures have widely been used in the field of orthopaedics to determine treatment outcomes; however, they may not always align with the patient\u27s goals for improvement following treatment. Therefore, we introduced the concept of patient-defined outcomes (PDOs): pretreatment goals or activities patients wish to improve following treatment, along with the patient-perceived difficulty and importance of these activities. This study aimed to evaluate PDOs in adults with hip dysplasia across 3 age groups while assessing patient variables for potential associations with choosing specific categories of activities.
Methods: We analyzed PDOs in 180 adults diagnosed with hip dysplasia, stratified into age groups: young adults (18-39 years), older adults (40-59 years), and senior adults (60 years or older). Patients listed at least 1 activity into the PDO questionnaire, followed by rating the difficulty and importance of the activity on a scale from zero to 10. PDOs were grouped into 6 thematic categories: sports, exercise, hobbies, activities of daily living (ADLs), work, and social engagement.
Results: ADLs were the most common PDO reported across all age groups, increasing from 47.2% of young adults to 68.2% of seniors, while exercise-related goals were the second most common reported PDO. Age and body mass index significantly positively related with choosing an ADL as a PDO (p = 0.017). Age (p = 0.041) and Pain Catastrophizing Score (p = 0.042) significantly negatively related, while University of California Activity Score (p = 0.020) showed a significant positive relationship, with reporting an exercise as a PDO. Almost all patients reported patient-perceived importance at the highest levels.
Conclusion: These findings underscore the impact hip dysplasia has on function, as most patients, regardless of age, expressed a desire to improve in basic ADLs. In addition, the importance levels of activities were consistently high across all age groups, highlighting the significance of aligning treatment goals with patient-centered outcomes.
Level of evidence: Level IV. See Instructions for Authors for a complete description of levels of evidence
Perceived Political Party Divide During the Pandemic: A Framework Linking Attitude Strength Toward COVID-19 Vaccines to Affective Polarization
No full textThis study examines how perceived political party divide may foster affective polarization during the COVID-19 pandemic. Drawing on nationally representative sample surveys of U.S. and South Korean adults, we investigate the relationship between attitude strength toward COVID-19 vaccines, perceived polarization, and affective polarization. Results suggest that individuals with stronger attitudes toward vaccines are more likely to perceive a greater ideological divide between political parties, which in turn, is associated with increased animosity toward the opposing party. Applying the mediation model to the South Korean sample yielded consistent findings, suggesting that the mechanism by which strong attitudes relate to negative emotions through perceived polarization may be generalizable across countries with a competitive two-party system, particularly in the context of COVID-19 vaccination attitudes. Our findings highlight perceived polarization as an important intermediary in the process of affective polarization, shedding light on the mechanisms driving partisan hostility in contemporary democracies
Tackling the burden of envenomation in Africa: advances, challenges, and strategic priorities for enhanced diagnosis and treatment
No full textVenomous animal envenomation remains a significant but neglected public health problem worldwide, with an estimated 5.4 million cases and up to 138,000 deaths annually. The burden is particularly acute in tropical and subtropical regions, especially sub-Saharan Africa, where rural and vulnerable populations face limited access to effective antivenoms and healthcare. Despite this, comprehensive data on envenomation incidence, clinical management, and outcomes remain scarce, hampering efforts to develop effective prevention and treatment strategies. This review synthesizes current knowledge on venomous animal diversity, epidemiology, and clinical manifestations globally, with a focus on Africa’s unique challenges. We examine critical gaps in antivenom production, distribution, and affordability, and highlight international initiatives, including the World Health Organization’s 2019 roadmap for snakebite envenoming control. Recent advances in diagnostics, therapeutics, and community engagement are discussed alongside persistent barriers to implementation. Finally, we propose strategic recommendations to strengthen surveillance, improve antivenom accessibility, and foster regional collaborations to reduce envenomation morbidity and mortality in Africa. Addressing these challenges requires coordinated global and local efforts to translate scientific advances into sustainable health outcomes for affected populations
On old dogs and new tricks: CT perfusion predicts hemorrhagic transformation after thrombectomy
No full textIntroduction
Hemorrhagic transformation is a major complication of large vessel occlusion (LVO) recanalization after mechanical thrombectomy in acute ischemic stroke. The hypoperfusion index ratio (HIR) quantifies the severity of cerebral hypoperfusion in the setting of an acute ischemic stroke using CT perfusion (CTP) to compare the volume of severely hypoperfused tissue (time-to-maximum [Tmax] \u3e 10 s) to total hypoperfused tissue (Tmax \u3e6 s), and has emerged as a potential predictor of ischemic core growth and poor outcomes. We investigated whether computed tomography perfusion (CTP) derived hypoperfusion index ratio correlates with the rate of hemorrhagic transformation. Methods
We conducted a retrospective cohort analysis of a prospectively maintained patient database. Included patients underwent mechanical thrombectomy for large vessel ischemic stroke from January 2019 to December 2022 at a single comprehensive stroke center. Patients were separated into 2 groups depending on whether hemorrhagic transformation developed. Hemorrhagic transformation included any hemorrhage that could be classified according to the ECASS criteria as hemorrhagic infarction (HI)1, HI2, parenchymal hematoma (PH)1 and PH2. Hypoperfusion index ratio on admission CTP was determined using VizAI software. Data were analyzed using Chi-square and Mann-Whitney U tests. Results
Among the 289 patients included (median age, 72.5; 41.5% female), 55 (19%) had hemorrhagic transformation. Patients with hemorrhagic transformation had a significantly higher hypoperfusion index ratio (median, 0 vs 0.2; P = 0.004) compared with those with no hemorrhagic transformation. Multivariable analysis showed that for every 0.1 increase in the hypoperfusion index ratio, there was a significant 4.64-fold increase in hemorrhagic transformation (OR 4.64; 95% CI 1.40 to 15.18; p = 0.011). Conclusion
In patients with LVO who underwent mechanical thrombectomy, a higher hypoperfusion index ratio on admission CTP was associated with an increased rate of hemorrhagic transformation. This suggests that the hypoperfusion index ratio could be used as a predictor for hemorrhagic transformation after mechanical thrombectomy
Unveiling the Strategic Impacts of Extending Membership-Based Free Shipping Programs Beyond the Online Marketplaces
No full textOnline marketplaces, which facilitate transactions between consumers and sellers, have transformed the shopping experience across multiple product categories. Addressing the challenges related to shipping associated with online purchases of physical products, many marketplaces have introduced membership-based free shipping (MFS) programs and concomitantly invested heavily in their logistics and fulfillment capabilities. Seeking to monetize these capabilities, Amazon recently extended its program to encompass outside sellers, enabling member consumers to get free shipping even when purchasing from external sources. Although such an extension offers the potential for additional revenue in the form of “logistics as a service” (LaaS), it also pits marketplace sellers against external counterparts, potentially cannibalizing marketplace sales analogous to a manufacturer experiencing a decline in sales of existing products while extending its product line. Using a game-theoretic model, we examine the implications of the extended MFS program on the marketplace, sellers, and consumers, which have yet to be studied. Contrary to common belief, our findings suggest that the extended MFS program can be a means to bolster the profitability of the marketplace’s core business. It may increase the commission revenue and/or reduce the fulfillment costs related to member consumers’ purchases on the marketplace. Moreover, all stakeholders in the marketplace ecosystem—the marketplace, internal and external sellers, and member consumers—can stand to benefit from the extended MFS program, albeit at nonmember consumers’ expense. Furthermore, the marketplace may incur a loss from LaaS itself but still derive overall benefit from the extended MFS program. Our results challenge the view that the extended MFS program is an LaaS offering that serves as a new source of profit. Instead, our results demonstrate that the extended MFS program could represent a strategic approach with novel ramifications that are distinct from those of traditional product line extension
Targeting Gliomas with Beta-Amyloid-Specific Dyes: A Novel Approach for In Vivo Staining and Potential Therapeutic Applications
No full textGliomas, the most common primary brain tumors, present significant diagnostic and treatment challenges due to their infiltrative nature and heterogeneity. Our previous research revealed that glioma tumors in both animals and humans accumulate beta-amyloid protein (Aβ), detectable through immunohistochemical methods or staining with amyloid-specific dyes. We hypothesize that beta-amyloid-specific dyes could serve as glioma markers, potentially enabling the delineation of glioma tumors or targeted therapeutics delivery. In this study, the specificity and blood-brain barrier permeability of two fluorescent beta-amyloid-specific dyes, Brilliant Blue G (BBG) and BODIPY-based Amyloid Probe-1 (BAP-1), were evaluated in C57Bl/6 mouse glioma implantation models using GL261 and KR158 glioma cells. The findings demonstrate that both BBG and BAP-1 selectively stain gliomas, providing a clear contrast from normal brain tissue. The study results open avenues for further development of glioma visualization methods and targeted therapeutic delivery strategies for clinical applications
Gravitational Wave and Radio Observations of Galactic Inspiraling Double Neutron Stars
No full textWe integrate the key results of our previous studies [8, 9, 11], providing a unified view on multimessenger and multiband (dual-line) observations of inspiraling double neutron stars (DNSs) in our Galaxy. Future space-based gravitational wave (GW) detectors, such as LISA, TianQin, and Taiji, are poised to bridge the detection gap of tight DNSs with orbital periods of approximately 10 min, which remain challenging to detect with radio telescopes. Our investigation will first explore GW and radio follow-up detection capabilities for Galactic inspiraling DNSs. Furthermore, next-generation ground-based GW observatories, such as Cosmic Explorer and Einstein Telescope, which are projected to be operational in the mid-2030s concurrently with LISA, TianQin, and Taiji, are expected to detect high-frequency GWs emitted by spinning NSs. This development will advance the study of dual-line GWs from DNSs. We then focus on GW waveform modeling for the spinning NS in a tight DNS and consider its potential role in inferring binary geometry and NS physics parameters by dual-line GW detection
Re-evaluating causal inference: Bias reduction in confounder-effect modifier scenarios
No full textPropensity Score Matching (PSM) is a widely used method for estimating causal treatment effects, but its performance can be limited in complex scenarios. This paper examines cases where a confounder also serves as an effect modifier and compares the bias-reduction performance of PSM with Inverse Probability Weighting (IPW). Using the University of California, Berkeley graduate admission data as an illustrative example, we show that PSM can produce biased estimates of the Average Treatment Effect (ATE) in such contexts. Through a simulation study, we demonstrate that PSM generally fails to adequately reduce bias for the ATE when a confounder is also an effect modifier, while IPW yields less biased estimates with lower Mean Squared Error (MSE). To validate these findings in a more real-world setting, we analyse data generated from a well-known matched-pairs experimental study of Mexico\u27s Seguro Popular de Salud (Universal Health Insurance) Program. From this experiment we derive observational data that incorporates confounders and effect modifiers and compare the performance of PSM and IPW estimators. Our results confirm that IPW consistently provides more accurate and reliable estimates of the ATE, with smaller bias, compared to PSM