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Direct Coupling of Continuum and Shell Elements in Large Deformation Problems
Full text linkIn many applications, thin shell-like structures are integrated within or attached to volumetric bodies. This includes reinforcements placed in soft matrix material in lightweight structure design, or hollow structures that are partially or completely filled. Finite element simulations of such setups are highly challenging. A brute force discretization of structural as well as volumetric parts using well-shaped three-dimensional elements may be accurate, but leads to problems of enormous computational complexity even for simple models. One desired alternative is the use of shell elements for thin-walled parts, as such a discretization greatly alleviates size restrictions on the underlying finite element mesh. However, the coupling of different formulations within a single framework is often not straightforward and may lead to locking if not done carefully. Neunteufel and Schöberl proposed a mixed shell element where, apart from displacements of the center surface, bending moments are used as independent unknowns. These elements were not only shown to be locking free and highly accurate in large-deformation regime, but also do not require differentiability of the shell surface and can handle kinked and branched shell structures. They can directly be coupled to classical volume elements of arbitrary order by sharing displacement degrees of freedom at the center surface, thus achieving the desired coupled discretization. As the elements can be used on unstructured meshes, adaptive mesh refinement based on local stress and bending moments can be used. We present computational results that confirm exceptional accuracy for problems where thin-walled structures are embedded as reinforcements within soft matrix material
Evaluating Nature-Based Versus Generic Physical Activity Programs to Address Chronic Health Conditions: Lessons from an Oregon (USA) Pilot Study
Full text linkEvidence appears to be building that direct exposure to natural landscapes characterized by significant green cover, such as forests, can help to reduce chronic health conditions such as obesity, stress, hypertension, chronic cardiovascular conditions, depression, anxiety, cancer, and diabetes. One way to encourage greater exposure to nature may be through the use of nature prescriptions, whereby clinicians formally recommend (or prescribe) time in nature to their patients. Based on self-reported data, we describe the implementation and lessons learned from a pilot field experiment examining the clinical use of nature-based versus conventional exercise recommendations in rural Oregon. We discuss the potential benefits of such recommendations, as well as identify several challenges and opportunities associated with field experiments seeking to evaluate whether nature prescriptions, offered as one part of patients’ overall treatment plans, meaningfully improve human health outcomes in clinical settings. We conclude with several recommendations for practitioners and researchers interested in implementing and evaluating nature-based exercise programs to improve public health
Predicting Strut Geometry of PCL and DMSO2 Biocomposites from Nozzle to Deposition in Bio-Scaffold 3D Printing
Full text linkThe field of tissue engineering increasingly demands accurate predictive models to optimize the 3D printing process of bio-scaffolds. This study presents a unified numerical model that predicts extrusion velocity and strut diameter based on printing conditions and the material properties of polycaprolactone (PCL) and dimethyl sulfone (DMSO2) composites. The extrusion velocity was simulated using Navier–Stokes equations, while the strut diameter was calculated via a surface energy model. For PCL, the extrusion velocity showed a temperature coefficient of 23.3%/°C and a pressure coefficient of 19.1% per 100 kPa; the strut diameter exhibited a temperature coefficient of 21.6%/°C and a pressure coefficient of 16.6% per 100 kPa. When blended with DMSO2, the lower viscosity and higher surface energy resulted in increased extrusion velocity and strut diameter. The proposed model achieved a high predictive accuracy, with determination coefficient (R²) values exceeding 0.95. These results demonstrate the model’s potential to optimize 3D printing parameters, guide biomaterial selection, and predict pore characteristics, ultimately supporting the rational design of tissue engineering scaffolds
Levels of the Nicotine Analog 6-Methyl Nicotine As a Naturally Formed Tobacco Alkaloid in Tobacco and Tobacco Products
Full text linkS-6-methyl nicotine (S-6MN) has appeared as a nicotine substitute in commercial electronic e-cigarette products and pouches, including with the claim that such use is not regulated under current U.S. law. This work describes an analytical chemistry based search for the natural S/R presence of 6MN and three other MN compounds in additive-free cured leaf tobaccos and in multiple commercial tobacco products. The samples were extracted using 5 N NaOH, then methyl t-butyl ether. The extracts were analyzed using gas chromatography (GC) with mass spectrometric (MS) detection, and liquid chromatography (LC) with high resolution MS/MS detection. GC peaks with the correct retention times and MS patterns were found and confirmed for 6MN. Further confirmation for the presence of 6MN was obtained by LC/MS/MS. The all-sample average level of 6MN was determined to be 0.32 µg per g of tobacco material; the levels were too low to determine the S/R distributions. For 2MN, strong but not fully confirmed (*) evidence was obtained; analytical results are presented for 2MN* at an all-sample average level of 0.10 µg per g of tobacco material. No evidence for either 4MN nor 5MN was found. Because most commercial nicotine is as extracted and purified from tobacco, 6MN can be expected in all such nicotine, and therefore in most nicotine-containing e-cigarettes (ENDS) as well as reagent-grade nicotine. Analyses of GC/MS data from past analyses of nine high-nicotine e-cigarette liquids purchased during the period 2018 to 2022 indicated a mean ± 1 s.d. result for 6MN of 6.3 ± 1.4 µg/mL
Testing Their Limits: Impact and Intentions of Standardized Testing in K-12 Schools
Full text linkThe integration of High-Stakes standardized testing into U.S. public education to serve as an accountability system has been a disputed issue since the No Child Left Behind Act (NCLB) mandated these assessments nationwide in 2002. NCLB aimed to locate and identify schools failing to reach Adequate Yearly Progress (AYP) and trigger a chain of interventions based on student performance, as an effort to track measurable outcomes from federal education funding. While supporters view these standardized tests as quantifiable data for school effectiveness in academics, critics challenge the claim of validity.
This review integrates current psychological research in the area of stress, to examine the neurological impacts of High Stakes testing-induced stress on cognitive functions, such as working memory and memory recall. Ultimately, this explores how this might affect scores and data coming from these assessments given to K-12 students. While moderate stress can enhance performance and memory consolidation, excessive academic stress is shown to negatively impact learning and core executive functions. By combining educational policy review with neurobiological insight, this paper adds perspective to debate on current assessment methods and advocates for reform to prioritize holistic development
Range-Dependent Meso-Scale Geoacoustic Seabed Quantification
Full text linkThis study presents a probabilistic one-step two-dimensional (2D) inversion method of spherical-wave reflection coefficient data to estimate the range-dependent structure and geoacoustic parameters along a track. The approach of inverting such datasets independently as one-dimensional (1D) layered models and merging them to a 2D section is feasible but computationally expensive. This study demonstrates a more parsimonious 2D parametrization for active source data recorded on a towed hydrophone array. The comparison of data variance reduction for 1D- and 2D-based results clearly favors the 2D parametrization described here
Codifying Capital: Legal Power, Racial Hierarchy, and the Gendered Dynamics of Law
Full text linkThis paper analyzes how law operates as a structuring force within racial capitalism by applying Austin Turk\u27s law as power framework. It explores how legal institutions not only reflect but actively reproduce racial and gender hierarchies through their functions. Drawing from foundational work by Cedric Robinson, W.E.B. Du Bois, Angela Harris, Kimberlé Crenshaw, and others, this paper defines racial capitalism as a system in which economic exploitation is inseparable from racial and gender domination. The first section contextualizes the emergence of racial capitalism and its intersection with gender, emphasizing how bodies are commodified and governed through legal regimes. The core analysis maps Turk\u27s five forms of legal power: police/violence, political, economic, ideological, and diversionary, onto case studies, policies, and legal doctrines. From prison systems to affirmative action discourse and civil court structures, the paper demonstrates how law sustains systems of expropriation and legitimizes inequality under the guise of neutrality. By bridging sociolegal theory and critical race scholarship, the work promotes questioning the presumed objectivity of legal institutions and highlights the importance of law in codifying the logic of capital. Ultimately, the paper showcases research that works to confront the racial capitalist order, and how legal scholars must reframe law not as an impartial arbiter but as an instrument of power shaped by historical and material forces
Contemporary Echoes From the Progressive Era: A Historical Reclamation Project of Caroline Pratt and Her Play-Based Pedagogy
Full text linkCaroline Pratt is the early childhood educator most never heard of. Pratt was a progressive era educator and reformer in 1900s New York City. Pratt developed a play based theory of education. She opened City & Country School in 1914 and her school is still operating utilizing many of the methods Pratt developed. Using first hand field research, archival research, and scholarly articles, I examine how Pratt developed her methods and how modern educators can use them today. The study of Pratt\u27s work and her school reveal a pragmatic approach to learning that educators today can adopt. In conclusion, play is the method that is the most effective for young children and modern educators would be wise to consider incorporating play methods into their own practice
Beyond Traditional Education: Graduation Rates at an Alternative High School
Full text linkThe study addressed the problem of practice of improving on-time graduation rates for students in alternative education settings. Traditional educational systems often fail to meet the unique needs of students in alternative education programs, which could lead to increased barriers towards on-time graduation. Based on improvement science principles, this research utilized Plan-Do-Study-Act (PDSA) cycles to systematically test and refine prioritized change ideas to mitigate these barriers with the goal of increasing graduation rates at the focus school. These change ideas included improving social emotional learning through teacher coaching, personalizing attendance calls, and developing individualized student success plans. Through rapid iterative cycles, the study sought to create an adaptable model of effective practices that could be replicated in other schools to address similar challenges. This research provides practical strategies to increase graduation rates and promote equitable outcomes for students in alternative education
How Different Forms of Exercise Affect Bone Mineral Density in Postmenopausal Women
Full text linkThis paper analyzed 20 studies to understand how bone health in postmenopausal women is impacted by different forms of exercise. The primary aspect of bone health examined in this paper is bone mineral density (BMD). Resistance and impact training demonstrated clear signs of maintenance and increases in BMD, particularly in the lumbar spine and femoral neck. Aquatic exercise demonstrated mixed results in positively impacting BMD in a significant way, but it’s worth noting that there were still some signs of increased BMD. Impact exercise on its own can maintain BMD, and these effects can be seen in total hip BMD. Age also seems to play a factor in how BMD is affected by exercise. Postmenopausal women 60 years old and older experienced greater changes in BMD from aerobic exercise and stretching. This was also the case with postmenopausal women 70 years old and older experienced greater changes in BMD from maintaining a unipedal stance than postmenopausal women younger than 70 years. Performing a combination of aerobic exercise and strength training has also shown as an effective way to maintain lumbar spine BMD. Resistance training and impact training are safe, feasible, maintain BMD, and promote healthy aging