In aerodynamic and hydrodynamic devices and locomotive organisms, passive appendages have practical purposes such as drag reduction and flow control. Although these appendages also affect the dynamics of freely falling bodies, underlying principles of their functions remain elusive. We investigate experimentally the dynamics of a falling sphere with a filament appended on its rear side by varying the ratio of filament length to sphere diameter ($l/D=0{-}3.0$) and sphere-to-fluid density ratio ($\rho _s/\rho _f= 1.06{-}1.36$), and maintaining a similar dimensionless moment of inertia ($I^* \approx 0.96$). At the Reynolds number of $O(10^3)$, a sphere without any filament exhibits vertical descent. However, the falling of the sphere with a filament is accompanied by periodic horizontal displacements, and the degree of zigzag motion is maximised under specific filament length. The filament induces periodic rotation of the sphere by shifting the centre of mass of the entire model and through the hydrodynamic interaction of the filament with the surrounding fluid. The rotation of the sphere increases the drag force acting on the model, reducing tangential velocity along the trajectory by 14 % compared to a plain sphere. Furthermore, the sphere rotation enhances the lift force normal to the trajectory, extending trajectory length by 5 %. These combined effects improve falling time over a certain vertical distance by 20 % compared to the plain sphere. With increasing sphere density, the effects of the filament on the falling dynamics weaken, because the offset distance between the centre of mass of the model and the geometric centre of the sphere becomes smaller.

Scalar dissipation rate (SDR) evolution in a stopping turbulent jet was analysed using direct numerical simulations and a theoretical approach. After the jet is stopped, a deceleration wave for the SDR propagates downstream with a speed similar to that for axial velocity. Upstream of the deceleration wave, mean centreline SDR becomes proportional to axial distance, and inversely proportional to the square of time. After passing of the deceleration wave, normalised radial profiles of SDR and its axial, radial and azimuthal components reach self-similar states, denoted decelerating self-similar profiles, which are different from their steady-state counterparts. Production and destruction terms in the mean SDR transport equation remain dominant in the decelerating self-similar state. The theoretical approach provides an explicit prediction for the radial profile of a turbulent fluctuation term of the mean SDR transport equation. Three turbulent SDR models are validated, and modifications suitable for the decelerating jet are proposed, based on a self-similarity analysis.

Aerosol-cloud interactions contribute significant uncertainty to modern climate model predictions. Analysis of complex observed aerosol-cloud parameter relationships is a crucial piece of reducing this uncertainty. Here, we apply two machine learning methods to explore variability in in-situ observations from the NASA ACTIVATE mission. These observations consist of flights over the Western North Atlantic Ocean, providing a large repository of data including aerosol, meteorological, and microphysical conditions in and out of clouds. We investigate this dataset using principal component analysis (PCA), a linear dimensionality reduction technique, and an autoencoder, a deep learning non-linear dimensionality reduction technique. We find that we can reduce the dimensionality of the parameter space by more than a factor of 2 and verify that the deep learning method outperforms a PCA baseline by two orders of magnitude. Analysis in the low dimensional space of both these techniques reveals two consistent physically interpretable regimes—a low pollution regime and an in-cloud regime. Through this work, we show that unsupervised machine learning techniques can learn useful information from in-situ atmospheric observations and provide interpretable results of low-dimensional variability.

Objectives/Goals: The creatine (Cr) system is impaired in Alzheimer’s disease (AD). Data show that creatine monohydrate (CrM) supplementation may improve AD symptoms in AD mouse models, but no human studies have been reported. Thus, we investigated whether an eight-week CrM supplementation was feasible and associated with increased brain creatine in patients with AD. Methods/Study Population: Twenty participants with probable AD were allocated to an open-label, eight-week intervention of 20 g/day CrM. Fasting blood draws were taken at baseline, 4-, and 8-week visits to measure serum creatine (Quest Diagnostics). 1H magnetic resonance spectroscopy was performed at baseline and 8-week visits to measure brain Cr as a ratio to unsuppressed water. Self-reported compliance (with assistance from study partners) was assessed with daily CrM trackers. The mean compliance percentage across all participants was used to describe overall compliance with the intervention. We used paired t-tests to analyze the mean changes in serum Cr levels from baseline to 4- and 8-week visits and the mean change in brain Cr from baseline to 8-week visits. Statistical significance was set at p<0.05. Results/Anticipated Results: Participants were 65% male with a mean age of 73.1±6.3 years. All participants completed the study, with 19 out of 20 achieving the dose compliance target of ≥80%. The mean self-reported dose intake was 90%. Serum Cr levels were significantly increased at 4- and 8-week visits compared to baseline (0.6±0.4 mg/dL vs. 14.0±9.9 mg/dL and 15.0±13.6 mg/dL, respectively; p<0.001). Brain Cr levels also significantly increased (330.5±36.80 i.u. vs. 366.9±57.52 i.u., p<0.001). Discussion/Significance of Impact: We are the first to demonstrate that 20 g/day of CrM for eight weeks is feasible and associated with increased brain Cr in patients with AD. Our findings support further investigation of brain target engagement of CrM and its efficacy in AD. With AD cases expected to rise, CrM could serve as an effective, affordable therapeutic to slow AD progression.

For a finite group G, let $\operatorname { {AD}}(G)$ denote the Fourier norm of the antidiagonal in $G\times G$. The author showed recently in [‘An explicit minorant for the amenability constant of the Fourier algebra’, Int. Math. Res. Not. IMRN 2023 (2023), 19390–19430] that $\operatorname { {AD}}(G)$ coincides with the amenability constant of the Fourier algebra of G and is equal to the normalized sum of the cubes of the character degrees of G. Motivated by a gap result for amenability constants from Johnson [‘Non-amenability of the Fourier algebra of a compact group’, J. Lond. Math. Soc. (2) 50 (1994), 361–374], we determine exactly which numbers in the interval $[1,2]$ arise as values of $\operatorname { {AD}}(G)$. As a by-product, we show that the set of values of $\operatorname { {AD}}(G)$ does not contain all its limit points. Some other calculations or bounds for $\operatorname { {AD}}(G)$ are given for familiar classes of finite groups. We also indicate a connection between $\operatorname { {AD}}(G)$ and the commuting probability of G, and use this to show that every finite group G satisfying $\operatorname { {AD}}(G)< {61}/{15}$ must be solvable; here, the value ${61}/{15}$ is the best possible.

For many people outside the South Korean popular music (K-pop) world, the December 2017 death of pop star Kim Jonghyun was a sad, but abstract event. Jonghyun, and dozens more like him, is a type of Korean celebrity known as an “idol.” In addition to being popular within Korea, idols are the public face of K-pop, which has become a worldwide phenomenon. This has made idols into incarnations of Korea and Korean culture, and brought the public's powerful disciplining gaze to bear on these young performers. In this paper, we explore how characteristics of life in contemporary Korea—including a high suicide rate, and intense pressures in education and employment—compound with idols' years of intense training in singing and dancing without adequate attention to physical, much less mental, health. Although this is the first incident of an A-list K-pop idol committing suicide, we propose that the nature of contemporary Korean celebrity, together with specific factors defining the lives of Korean youth, create an environment where suicide may become even more prevalent, escalating Korea's suicide rate, which is already among the world's highest. Finally, we discuss the potential impact of Jonghyun's suicide on K-pop fans.

The essay “Specters of East Asia” is the contribution of playwright, actor, and scholar Choi Jinseok to the volume Still Hear the Wound. It is based on a presentation made by Choi in March, 2007, at the Sakima Art Museum in Okinawa, whose courtyard faces directly onto the U.S. Marine Air Station Futenma, itself bordered by winding roads and chain-link fences. While protests over construction of a new airstrip in the coastal fishing village of Henoko swelled and continued in Okinawa, protests which continue in 2016, the museum hosted workshops in 2004 and 2007 as part of a series of events organized by the Asia, Politics, Art Project founded by poet/philosopher Lee Chonghwa of Seikei University, Tokyo. Its members were scholars, critics, and young artists dedicated to exploring, through art, often marginalized and suppressed memories of colonial violence shared across national boundaries in East Asia.

This article exposes human rights violations committed at Brothers Home in Busan, South Korea in the 1970s and 1980s, identifying their structural causes and discussing Korean society's efforts to address them. From 1975 to 1987, Brothers Home was the largest group residential facility for the homeless, the ill, the disabled, and the poor—a program that was even commended by the Korean government. However, over the years, various human rights abuses led to the death of 657 residents. While these violations remained hidden from public view for almost 25 years, survivors and supporters waged a long battle to bring them to light. Recently, the Truth and Reconciliation Commission investigated and confirmed the human rights violations as state violence. In this essay, the authors assess the significance this case holds for Korean society.

Monetary sanctions in law enforcement, including fines, forfeitures, and related fees, are susceptible to exploitation by agencies for self-serving profit motives. However, a key challenge in addressing this issue is disentangling the agencies’ profit-driven motives from their genuine commitment to upholding law and order. Against this backdrop, this study examines a novel policy design proposal: redirecting revenues from law enforcement to fund local nonprofits. This approach seeks to eliminate conflicts of interest without restricting the use of monetary sanctions as a tool for law enforcement, while simultaneously channeling revenues toward community benefits. Experimental evidence based on a representative sample of US adults (n = 1,030) further highlights this approach’s potential to improve public perceptions of, and attitudes toward, law enforcement agencies. The study concludes by discussing the broader implications of this proposal for the political economy of law enforcement, as well as key considerations and potential challenges for its implementation.

In this study, measurements and numerical analyses of the temperature distribution of exhaust gas passing through two types of mixers using a micro turbojet engine were performed to investigate the flow mixing performance based on the shape of the mixer, which mixes the bypass air and core air in a gas turbine turbofan engine. To study the mixing characteristics of the mixer, compressed air was supplied through an external duct mounted on a micro turbojet engine to simulate bypass flow, and a system in which hot gas and compressed air were mixed and ejected into the atmosphere was fabricated. A confluent-type mixer and a mixer with 8-lobed mixer channels in the form of a sine wave were used for the experiment. The exhaust gas temperature was measured based on the distance from the nozzle outlet at bypass ratios of 0.5, 1.0 and 1.4. The results showed that the lobed mixer is more effective than the confluent mixer in lowering the exhaust gas temperature as the bypass ratio increased. Numerical analysis results indicated that, in the case of the confluent mixer, flow mixing is primarily performed by shear flow owing to the velocity difference between the core gas and the bypass air. In contrast, in the case of a lobed mixer, flow mixing is achieved through rotational motion and transverse flow. In addition, when the number of lobe channels increased from 8 to 12, the rotational motion increased and the mixing performance improved. Furthermore, infrared signal calculation results confirmed that, as the number of lobe channels increased, improved flow mixing effectively reduced the infrared signal. We conclude that this study helps understand the mixing characteristics of the flow according to the shape of the mixer at various bypass ratios and determine their effect on the characteristics of the infrared signal.

This study examines Luciano Berio's integration of twentieth-century linguistic and semiotic concepts in his works Sinfonia and Coro, focusing on the interplay between sound, meaning, and structure. It highlights Berio's exploration of the unconscious mind and the idea of ‘universality of experience', suggesting that humans may possess an innate musical ability similar to that of language. The article also discusses the concept of the ‘theatre of the mind', where Berio combines musical and textual elements to evoke images or situations for the audience's interpretation. Through an analysis of the third movement of Sinfonia and Coro, the study illustrates how Berio implicitly develops a system of signification that evokes meaning, showcasing both musical and textual productivity, along with the notion of ‘the infinite use of finite means’. This exploration contributes to understanding how twentieth-century linguistics and semiotics can inform contemporary music and signify meaning within it.

We examine a variant of ultimatum bargaining in which principals may delegate their proposal decision to agents hired from a competitive market. Contrary to several prior studies, we find that when principals must use agents, the resulting proposals are significantly higher than when principals make proposals themselves. In reconciling our results with prior findings, we conclude that both the rejection power afforded to responders and the structure of principal-agent contracts can play significant roles in the nature of outcomes under delegated bargaining.