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The physical fidelity of turbulence models can significantly benefit from a partial resolution of fluctuations, but doing so often comes with a significant increase in computational cost. To explore this trade-off in the context of wall-bounded flows, this paper introduces a framework for Turbulence-Resolving Integral Simulations (TRIS) with the goal of efficiently resolving the largest motions using two-dimensional fields defined by instantaneous wall-normal integration of velocity and pressure. Self-sustaining turbulence with qualitatively realistic large-scale structures is demonstrated for TRIS on an open-channel (half-channel) flow using moment-of-momentum integral equations derived from Navier-Stokes with relatively simple closure approximations. Evidence from Direct Numerical Simulations (DNS) suggests that such an approach can resolve 35-40% of the Reynolds shear stress at arbitrarily high Reynolds number. The current implementation of TRIS can match this resolution while simulating one flow through time in ~1 minute on a single processor, even for very large Reynolds number. The present proof-of-concept TRIS results shown here rely on parameter tuning, and some quantitative differences with DNS spectra are observed, motivating ongoing and future efforts towards physics-based closures as well as extension to more general flow configurations such as boundary layers on immersed objects., Comment: Main Paper - 10 pages and 4 figures. Supplementary Material - 7 pages and 2 figures. JFM Rapids Article

$FeCr_2S_4$ is a ferrimagnet with two oppositely-ordered spin sublattices (Fe and Cr), connected via superexchange interaction, giving a non-zero net magnetic moment. We show how the magnetic dynamics of the sublattices can be selectively manipulated by resonantly perturbing the Fe sublattice using ultrashort laser pulses. The mid-infrared excitation through intra-atomic Fe $d-d$ transitions triggers a markedly slower magneto-optical Kerr effect dynamics compared to an off-resonant pumping affecting both the two sublattices simultaneously. The analysis and conclusions are supported by probing resonantly and off-resonantly to the Fe sublattice., Comment: 29 pages, 19 figures

We present an experimental implementation of a chirped mid-infrared (mid-IR) high-power laser source with variable center frequency between 4 THz to 30 THz and continuously tunable frequency sweep of up to 20 % within one pulse, with a pulse duration of 2 ps. The peak electric field obtained at 4 THz is 1.5 MV/cm. We generate the mid-IR light using a difference-frequency generation (DFG) process with two phase-locked, chirped IR pulses. The obtained mid-IR electric field waveform is characterized using electro-optic sampling. We compare our experimental results with the predictions of numerical simulations. The results indicate the potential for efficient driving of vibrational modes into a strongly anharmomic regime, in cases where using Fourier-transform-limited pulses to achieve similar vibrational amplitudes would lead to dielectric breakdown., Comment: 13 pages, 5 figures

Although there is strong evidence that many long GRBs are associated with the collapse of a massive star, tantalizing results in recent years have upended the direct association of all long GRBs with massive stars. In particular, kilonova signals in some long GRB light curves as well as a suggested uptick in the rate density of long GRBs at low redshifts (deviating significantly from the star formation rate) suggest that compact object mergers may be a non-negligible fraction of the long GRB population. Here we investigate the contribution of white dwarf-black hole mergers to the long GRB population. We present evidence for the deviation of the long GRB rate density from the star formation rate at low redshifts, and provide analytic and numerical arguments for why a white dwarf-black hole merger system may be a viable progenitor to explain this deviation. We show the range of parameter space in which the durations, energetics, and rates of these systems can account for a significant sub-population of low-redshift long GRBs., Comment: Accepted for publication in MNRAS

Traumatic brain injury (TBI) can cause a range of cognitive and communication challenges that negatively affect social participation in both face-to-face interactions and computer-mediated communication. In particular, individuals with TBI report barriers that limit access to participation on social media platforms. To improve access to and use of social media for users with TBI, we introduce the Social Media Accessibility and Rehabilitation Toolkit (\textbf{SMART-TBI}). The toolkit includes five aids (Writing Aid, Interpretation Aid, Filter Mode, Focus Mode, and Facebook Customization) designed to address the cognitive and communicative needs of individuals with TBI. We asked eight users with moderate-severe TBI and five TBI rehabilitation experts to evaluate each aid. Our findings revealed potential benefits of aids and areas for improvement, including the need for psychological safety, privacy control, and balancing business and accessibility needs; and overall mixed reactions among the participants to AI-based aids., Comment: In Proceedings The 26th International ACM SIGACCESS Conference on Computers and Accessibility (ASSETS'24)

Postsecondary readiness enables students to pursue their dreams, contribute to society, and thrive in the global economy. Since many accountability systems include a postsecondary readiness indicator in formal evaluations of schools and districts, it benefits educators, families, researchers, policymakers, and other education partners to understand how postsecondary readiness is defined, measured, and used. This brief, produced by the Region 15 Comprehensive Center, explains how states define and measure postsecondary readiness, an important step toward improving how such measures function within state accountability systems. Region 15 Comprehensive Center staff identified four main findings about the use of postsecondary readiness indicators, the types of measures included in the indicators, and how much weight indicators are given in accountability systems: (1) More than three of four ESSA plans contained a postsecondary readiness indicator; (2) States included three main types of measures in postsecondary readiness indicators: academic, career, and military; (3) Postsecondary readiness indicators focused most heavily on academic and career measures and less on military measures; and (4) Weighting of the postsecondary readiness indicator varies widely from state to state.

Materials with linear electronic dispersion often feature high carrier mobilities and unusually strong nonlinear optical interactions. In this work, we investigate the THz nonlinear dynamics of one such material, HgCdTe, with an electronic band dispersion heavily dependent on both temperature and stoichiometry. We show how the band gap, carrier concentration and band shape together determine the nonlinear response of the system. At low temperatures, carrier generation from Zener tunneling dominates the nonlinear response with a reduction in the overall transmission. At room temperature, quasi-ballistic electronic dynamics drive the largest observed nonlinear optical interactions, leading to a transmission increase. Our results demonstrate the sensitivity of these nonlinear optical properties of narrow-gap materials to small changes in the electronic dispersion and carrier concentration., Comment: 48 pages, 21 figures

The nature of the "failed" ferroelectric transition in SrTiO3 has been a long-standing puzzle in condensed matter physics. A compelling explanation is the competition between ferroelectricity and an instability with a mesoscopic modulation of the polarization. These polarization density waves, which should become especially strong near the quantum critical point, break local inversion symmetry and are difficult to probe with conventional x-ray scattering methods. Here we combine a femtosecond x-ray free electron laser (XFEL) with THz coherent control methods to probe inversion symmetry breaking at finite momenta and visualize the instability of the polarization on nanometer lengthscales in SrTiO3. We find polar-acoustic collective modes that are soft particularly at the tens of nanometer lengthscale. These precursor collective excitations provide evidence for the conjectured mesoscopic modulated phase in SrTiO3.

Assistive technologies for adults with Down syndrome (DS) need designs tailored to their specific technology requirements. While prior research has explored technology design for individuals with intellectual disabilities, little is understood about the needs and expectations of adults with DS. Assistive technologies should leverage the abilities and interests of the population, while incorporating age- and context-considerate content. In this work, we interviewed six adults with DS, seven parents of adults with DS, and three experts in speech-language pathology, special education, and occupational therapy to determine how technology could support adults with DS. In our thematic analysis, four main themes emerged, including (1) community vs. home social involvement; (2) misalignment of skill expectations between adults with DS and parents; (3) family limitations in technology support; and (4) considerations for technology development. Our findings extend prior literature by including the voices of adults with DS in how and when they use technology., Comment: 17 pages, 4 figures, to be published in ACM CHI 2024

The supermassive black holes (SMBHs) that power active galactic nuclei found at $z > 6$ were formed during the epoch of reionization. Because reionization is an inhomogeneous process, the physical properties of SMBH host galaxy environments will vary spatially during reionization. We construct a semi-analytic model to estimate the impact of reionization on SMBH growth. Using a series of merger trees, reionization models, and black hole growth models, we find that early reionization can reduce an SMBH's mass by up to [50, 70, 90] % within dark matter halos of mass [$10^{12}$, $10^{11}$, $10^{10}$] M$_{\odot}$ by $z$ = 6. Our findings also suggest that the redshift range in which black hole growth is impacted by reionization strongly depends on whether the Eddington accretion rate can be exceeded. If so, we find that black hole masses are significantly suppressed principally during the early phases of reionization ($z$ > 10), while they are more readily suppressed across the full redshift range if super-Eddington growth is not allowed. We find that the global average impact of reionization may be to reduce the masses of black holes residing in < 10$^{11}$ M$_{\odot}$ halos by a factor of > 2. The census of supermassive black holes being uncovered by the James Webb Space Telescope may offer a means to test the basic prediction that more massive black holes reside in cosmological volumes that are reionized at later times., Comment: 12 pages, 8 figures. Accepted to ApJ

Resonant driving of electronic transitions with coherent laser sources creates quantum coherent superpositions of the involved electronic states. Most time-resolved studies have focused on gases or isolated subsystems embedded in insulating solids, aiming for applications in quantum information. Here, we demonstrate coherent control of orbital wavefunctions in pyrochlore $Tb_{2}Ti_{2}O_{7}$, which forms an interacting spin liquid ground state. We show that resonant excitation with a strong THz pulse creates a coherent superposition of the lowest energy Tb 4f states before the magnetic interactions eventually dephase them. The coherence manifests itself as a macroscopic oscillating magnetic dipole, which is detected by ultrafast resonant x-ray diffraction. The induced quantum coherence demonstrates coherent control of orbital wave functions, a new tool for the ultrafast manipulation and investigation of quantum materials.