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You Thought You Ate: How Capitalism Constructs Black Women’s Body Image and Relationship to Food
No full textA High-Order Eulerian–Lagrangian Runge–Kutta Finite Volume (EL–RK–FV) Method For Scalar Nonlinear Conservation Laws
No full textWe present a class of high-order Eulerian–Lagrangian Runge–Kutta finite volume methods that can numerically solve Burgers’ equation with shock formations, which could be extended to general scalar conservation laws. Eulerian–Lagrangian (EL) and semi-Lagrangian (SL) methods have recently seen increased development and have become a staple for allowing large time-stepping sizes. Yet, maintaining relatively large time-stepping sizes post shock formation remains quite challenging. Our proposed scheme integrates the partial differential equation on a space-time region partitioned by linear approximations to the characteristics determined by the Rankine–Hugoniot jump condition. We trace the characteristics forward in time and present a merging procedure for the mesh cells to handle intersecting characteristics due to shocks. Following this partitioning, we write the equation in a time-differential form and evolve with Runge–Kutta methods in a method-of-lines fashion. High-resolution methods such as ENO and WENO-AO schemes are used for spatial reconstruction. Extension to higher dimensions is done via dimensional splitting. Numerical experiments demonstrate our scheme’s high-order accuracy and ability to sharply capture post-shock solutions with large time-stepping sizes
An Interpolation Approach To L\u3csup\u3e∞\u3c/sup\u3e A Priori Estimates For Elliptic Problems With Nonlinearity On The Boundary
No full textWe establish an explicit L∞(Ω) a priori estimate for weak solutions to subcritical elliptic problems with nonlinearity on the boundary, in terms of the powers of their ¹(Ω) norms. To prove our result, we combine in a novel way Moser type estimates together with elliptic regularity and Gagliardo–Nirenberg interpolation inequality. We illustrate our result with an application to subcritical problems satisfying Ambrosetti-Rabinowitz condition
Reduced Augmentation Implicit Low-Rank (RAIL) Integrators For Advection-Diffusion And Fokker–Planck Models
No full textThis paper introduces a novel computational approach termed the reduced augmentation implicit low-rank (RAIL) method by investigating two predominant research directions in low-rank solutions to time-dependent partial differential equations (PDEs): dynamical low-rank (DLR), and step-and-truncation (SAT) tensor methods. The RAIL method is designed to enhance the efficiency of traditional full-rank implicit solvers, while maintaining accuracy and stability. We consider spectral methods for spatial discretization, and diagonally implicit Runge–Kutta and implicit-explicit RK methods for time discretization. The efficiency gain is achieved by investigating low-rank structures within solutions at each Runge–Kutta (RK) stage. In particular, we develop a reduced augmentation procedure to predict the basis functions to construct projection subspaces. This procedure balances algorithm efficiency and accuracy by incorporating as many bases as possible from previous RK stages, and by optimizing the basis representation through a singular value decomposition truncation. As such, one can form implicit schemes for updating basis functions in a dimension-by-dimension manner, similar in spirit to the K-L step in the DLR framework. We propose applying a postprocessing step to maintain global mass conservation. We validate the RAIL method through numerical simulations of advection-diffusion problems and a Fokker–Planck model. Our approach generalizes and bridges the DLR and SAT approaches, offering a comprehensive framework for efficiently and accurately solving time-dependent PDEs in the low-rank format with implicit treatment
Single-Fibril Förster Resonance Energy Transfer Imaging And Deep Learning Reveal Concentration Dependence Of Amyloid β 42 Aggregation Pathways
No full textAmyloid fibril formation is a highly heterogeneous process as evidenced by polymorphism in fibril structure. It has been suggested that different polymorphs are associated with different diseases or disease subtypes. Detailed characterization of this heterogeneity is a key to understanding the aggregation mechanism and, possibly, the disease mechanism. In this work, we develop Förster resonance energy transfer (FRET) imaging of amyloid fibril formation in real time and investigate the concentration-dependent heterogeneous fibril formation of amyloid β 42 (Aβ42). We incubated a mixture of unlabeled and labeled (5% donor and 5% acceptor) Aβ42, followed aggregation, and characterized individual fibrils in terms of FRET efficiency, acceptor fluorescence lifetime, and stoichiometry of the donor- and acceptor-labeled monomers incorporated into the fibrils. By FRET efficiency, we found that there are two distinct species at a relatively low concentration, 2 μM. The high FRET species appears first, but the low FRET species becomes dominant at later times. On the other hand, the high FRET species dominates throughout aggregation at 4 μM. The broad FRET efficiency distributions are consistent with those calculated from various known fibril structures. In addition to the FRET efficiencies, different acceptor lifetimes at the two concentrations and broad acceptor density distributions indicate at least three structurally distinct fibril species exist at each concentration, which also differ between the two different concentrations. The distinct heterogeneity in fibril formation pathways depending on the monomer concentration highlights the importance of understanding heterogeneity in the context of the biologically relevant aggregation environment
Freedom And Its Discontents: A Relational Reconstruction
No full textWhile the value placed on freedom may be universal, the meaning of the concept and its implications vary widely across history and culture. It is the concept of freedom central to the Western tradition that I wish to explore in the present offering – with special attention to the concept of free will. As I will propose, there are tensions within the longstanding assumptions upon which the concept of free agency rests. These tensions not only create insoluble philosophic problems, but more importantly, foster a chronic condition of social conflict. Today, such conflict increases in both its reach and intensity. It is in this context that I will introduce a relational conception of human action, an alternative that removes these tensions from their regnant position in cultural life. Further, when the implications of this relational view are played out, alternative routes to the amelioration of conflict are opened – from the personal level to the global. I do not include in this account issues of slavery, incarceration, or other instances of full human confinement. My concerns are with the implications of presuming voluntary choice for the state of wellbeing in everyday life
University Keywords
No full textUniversity Keywords gathers, contextualizes, and develops original understandings of 27 key terms that define the study and operation of the American university today. Editor Andy Hines and the book\u27s contributors invite readers to rethink the university beyond its public image as a space of learning and understand how it also operates as a real estate powerhouse, a hedge fund, a debt machine, and even a crisis-producing entity embedded in the broader American economy.
Through essays written by over thirty contributors from a variety of disciplines, this book examines the university\u27s intersecting functions, from its financial entanglements to its often-contradictory roles in society. Contributors illustrate how universities simultaneously link and separate communities—faculty, students, nurses, janitors, and the surrounding public—through administrative processes that promote a sense of isolation and division, even within shared spaces. By defining and expanding the terms that drive public and scholarly conversations about postsecondary education, University Keywords situates what appear to be auxiliary aspects of colleges and universities as directly impacting and at times displacing the central academic mission of these institutions.
In its role as a crucible for societal hierarchies and economic interests, the university both drives and reflects major shifts in social structure, labor practices, and economic power. The book\u27s exploration of key terms like debt, police, and union offers readers a new framework for understanding the university\u27s transformation into an instrument of capital accumulation, as well as its ongoing relevance in the fight for a world where education, labor, and social justice converge
Nowcasting Disruptions To Human Capital Formation: Evidence From High-Frequency Household And Geospatial Data In Rural Malawi
No full textExposure to extreme weather events and other adverse shocks has led to an increasing number of humanitarian crises in developing countries in recent years. These events cause acute suffering and compromise future welfare by adversely impacting human capital formation among vulnerable populations. Early and accurate detection of adverse shocks to food security, health, and schooling is critical to facilitating timely and well-targeted humanitarian interventions to minimize these detrimental effects. Yet monitoring data are rarely available with the frequency and spatial granularity needed. This paper uses high-frequency household survey data from the Rapid Feedback Monitoring System, collected in 2020–23 in southern Malawi, to explore whether combining monthly data with publicly available remote-sensing features improves the accuracy of machine learning extrapolations across time and space, thereby enhancing monitoring efforts. In the sample, illnesses and schooling disruptions are not reliably predicted. However, when both lagged outcome data and geospatial features are available, intertemporal and spatiotemporal prediction of food insecurity indicators is promising
Counterintuitive Particle Confinement In A Helical Force-Free Plasma
No full textThe force-free magnetic field solution formed in a high-aspect ratio cylinder is a non-axisymmetric (��=1), closed magnetic structure that can be produced in laboratory experiments. Force-free equilibria can have strong field gradients that break the usual adiabatic invariants associated with particle motion, and gyroradii at measured conditions can be large relative to the gradient scale lengths of the magnetic field. Individual particle motion is largely unexplored in force-free systems without axisymmetry, and it is unclear how the large gradients influence confinement. To understand more about how particles remain confined in these configurations, we simulate a thermal distribution of protons moving in a high-aspect-ratio force-free magnetic field using a Boris stepper. The particle loss is logarithmic in time, which suggests trapping and/or periodic orbits. Many particles do remain confined in particular regions of the field, analogous to trapped particles in other magnetic configurations. Some closed flux surfaces can be identified, but particle orbits are not necessarily described by these surfaces. We show examples of orbits that remain on well-defined surfaces and discuss the statistical properties of confined and escaping particles