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In December 2023, TICAS published new research on the College Affordability Gap--the gap between students' total cost of attendance and non-loan aid available to them--in California, Michigan, and New York, with a focus on students eligible for Pell Grants. Our new report builds on this research with data from nine additional states (Colorado, Indiana, Louisiana, Massachusetts, Minnesota, New Jersey, Oregon, Rhode Island, and Washington), all of whom are part of TICAS' State Policy Network to Advance Debt-Free College. This research helps to define the magnitude of the affordability crisis students face and offers recommendations for state and federal policymakers to incrementally improve college affordability.

One manifestation of classical ergodicity is a complete loss of memory of the initial conditions due to the eventual uniform exploration of phase space. In quantum versions of the same systems, classical ergodic traits can be broken. Here, we extend the concept of quantum scars in new directions, more focused on ergodicity and infinite time averages than individual eigenstates. We specifically establish a union of short and long-term enhancements in terms of a \emph{quantum birthmark} (QB). Subsequently, we show (1) that the birth and early evolution of a nonstationary state is remembered forever in infinite time averages, and (2) that early recurrences in the autocorrelation function inevitably lead to nonergodic flow over infinite times. We recount here that phase space cannot be explored ergodically if there are early recurrences (well before the Heisenberg time) in the autocorrelation of the initial nonstationary quantum state. Employing random matrix theory, we show that QB extends beyond individual states to entire subspaces or ``{\it birthplaces}" in Hilbert space. Finally, we visualize scar-amplified QBs unveiled within the time-averaged probability density of a wavepacket in a stadium system. By transcending the quantum scarring, QB delivers a new paradigm for understanding the elusive quantum nature of ergodicity.

Quantum error mitigation is regarded as a possible path to near-term quantum utility. The methods under the quantum error mitigation umbrella term, such as probabilistic error cancellation, zero-noise extrapolation or Clifford data regression are able to significantly reduce the error for the estimation of expectation values, although at an exponentially scaling cost, i.e., in the sampling overhead. In this work, we present a straightforward method for reducing the sampling overhead of PEC on Clifford circuits (and Clifford subcircuits) via Pauli error propagation alongside some classical preprocessing. While the methods presented in this work are restricted to Clifford circuits, we argue that Clifford sub circuits often occur in relevant calculations as for example the resource state generation in measurement based quantum computing.

The quantum acoustic framework has recently emerged as a non-perturbative, coherent approach to electron-lattice interactions, uncovering rich physics often obscured by perturbative methods with incoherent scattering events. Here, we model the coupled dynamics of electrons and acoustic lattice vibrations within this framework, representing lattice vibrations as coherent states and electrons as quantum wavepackets. We derive and numerically implement electron backaction on the lattice, providing both visual and quantitative insights into electron wavepacket evolution, self-trapping, and the formation of small acoustic polarons. We investigate polaron binding energies across varying material parameters and compute key observables-including mean square displacement, kinetic energy, potential energy, and vibrational energy-over time. Our findings reveal the conditions that favor polaron formation, which is enhanced by low temperatures, high deformation potential constants, slow sound velocities, high effective masses, and small Fermi surfaces. Additionally, we explore the impact of external electric and magnetic fields, showing that while polaron formation remains robust under moderate fields, it is weakly suppressed at higher field strengths. These results deepen our understanding of polaron dynamics and pave the way for future studies into non-trivial transport behavior in quantum materials., Comment: 11 pages, 5 figures

We find that Anderson localization ceases to exist when a random medium begins to move, but another type of fundamental quantum effect, Planckian diffusion $D = \alpha\hbar/m$, rises to replace it, with $\alpha $ of order of unity. Planckian diffusion supercedes the Planckian speed limit $\tau= \alpha \hbar/k_B T,$ as it not only implies this relation in thermal systems but also applies more generally without requiring thermal equilibrium. Here we model a dynamic disordered system with thousands of itinerant impurities, having random initial positions and velocities. By incrementally increasing their speed from zero, we observe a transition from Anderson localization to Planckian diffusion, with $\alpha$ falling within the range of $0.5$ to $2$. Furthermore, we relate the breakdown of Anderson localization to three additional, distinctly different confirming cases that also exhibit Planckian diffusion $D\sim \hbar/m$, including one experiment on solid hydrogen. Our finding suggests that Planckian diffusion in dynamic disordered systems is as universal as Anderson localization in static disordered systems, which may shed light on quantum transport studies.

Recent advancements in large language model(LLM) performance on medical multiple choice question (MCQ) benchmarks have stimulated interest from healthcare providers and patients globally. Particularly in low-and middle-income countries (LMICs) facing acute physician shortages and lack of specialists, LLMs offer a potentially scalable pathway to enhance healthcare access and reduce costs. However, their effectiveness in the Global South, especially across the African continent, remains to be established. In this work, we introduce AfriMed-QA, the first large scale Pan-African English multi-specialty medical Question-Answering (QA) dataset, 15,000 questions (open and closed-ended) sourced from over 60 medical schools across 16 countries, covering 32 medical specialties. We further evaluate 30 LLMs across multiple axes including correctness and demographic bias. Our findings show significant performance variation across specialties and geographies, MCQ performance clearly lags USMLE (MedQA). We find that biomedical LLMs underperform general models and smaller edge-friendly LLMs struggle to achieve a passing score. Interestingly, human evaluations show a consistent consumer preference for LLM answers and explanations when compared with clinician answers.

We demonstrate that vision language models (VLMs) are capable of recognizing the content in audio recordings when given corresponding spectrogram images. Specifically, we instruct VLMs to perform audio classification tasks in a few-shot setting by prompting them to classify a spectrogram image given example spectrogram images of each class. By carefully designing the spectrogram image representation and selecting good few-shot examples, we show that GPT-4o can achieve 59.00% cross-validated accuracy on the ESC-10 environmental sound classification dataset. Moreover, we demonstrate that VLMs currently outperform the only available commercial audio language model with audio understanding capabilities (Gemini-1.5) on the equivalent audio classification task (59.00% vs. 49.62%), and even perform slightly better than human experts on visual spectrogram classification (73.75% vs. 72.50% on first fold). We envision two potential use cases for these findings: (1) combining the spectrogram and language understanding capabilities of VLMs for audio caption augmentation, and (2) posing visual spectrogram classification as a challenge task for VLMs.

Silicon photo-multipliers (SiPM) have been replacing traditional photomultiplier tubes in most light sensing applications. However, when large detection surface coverage is needed, photomultipliers (PMTs) are still the preferred choice. The main reasons are the sensor thermal noise and the duration of the fast component of its signal, both increasing with the sensor surface. In this work we propose an application specific integrated circuit (ASIC), called Fast ANalog SiPM Integrated Circuit (FANSIC), for the readout of large SiPMs addressing these limitations. The ASIC has an active summation stage, which allows to divide a large detection surface into smaller ones offering faster response both in single ended and differential outputs. The high input bandwidth allows to reach full-width-half-maximum (FWHM) signals or the order of 3--5 ns which limits the impact of internal and external uncorrelated noise. The results of the first implementation of FANSIC, designed in CMOS 65 nm technology, is described in this paper., Comment: 21 pages, 17 figures, journal

In a supervised classification split conformal/inductive framework with $K$ classes, a calibration sample of $n$ labeled examples is observed for inference on the label of a new unlabeled example. In this work, we explore the case where a "batch" of $m$ independent such unlabeled examples is given, and a multivariate prediction set with $1-\alpha$ coverage should be provided for this batch. Hence, the batch prediction set takes the form of a collection of label vectors of size $m$, while the calibration sample only contains univariate labels. Using the Bonferroni correction consists in concatenating the individual prediction sets at level $1-\alpha/m$ (Vovk 2013). We propose a uniformly more powerful solution, based on specific combinations of conformal $p$-values that exploit the Simes inequality (Simes 1986). Intuitively, the pooled evidence of fairly "easy" examples of the batch can help provide narrower batch prediction sets. We also introduced adaptive versions of the novel procedure that are particularly effective when the batch prediction set is expected to be large. The theoretical guarantees are provided when all examples are iid, as well as more generally when iid is assumed only conditionally within each class. In particular, our results are also valid under a label distribution shift since the distribution of the labels need not be the same in the calibration sample and in the new `batch'. The usefulness of the method is illustrated on synthetic and real data examples., Comment: 27 pages, 6 figures, 6 tables

We present an autodifferentiable rejection sampling algorithm termed Rejection Sampling with Autodifferentiation (RSA). In conjunction with reweighting, we show that RSA can be used for efficient parameter estimation and model exploration. Additionally, this approach facilitates the use of unbinned machine-learning-based observables, allowing for more precise, data-driven fits. To showcase these capabilities, we apply an RSA-based parameter fit to a simplified hadronization model., Comment: 12 pages, 5 figures

The Water Cherenkov Detector Array (WCDA) is one of the components of Large High Altitude Air Shower Observatory (LHAASO) and can monitor any sources over two-thirds of the sky for up to 7 hours per day with >98\% duty cycle. In this work, we report the detection of two outbursts of the Fanaroff-Riley I radio galaxy NGC 1275 that were detected by LHAASO-WCDA between November 2022 and January 2023 with statistical significance of 5.2~$\sigma$ and 8.3~$\sigma$. The observed spectral energy distribution in the range from 500 GeV to 3 TeV is fitted by a power-law with a best-fit spectral index of $\alpha=-3.37\pm0.52$ and $-3.35\pm0.29$, respectively. The outburst flux above 0.5~TeV was ($4.55\pm 4.21)\times~10^{-11}~\rm cm^{-2}~s^{-1}$ and ($3.45\pm 1.78)\times~10^{-11}~\rm cm^{-2}~s^{-1}$, corresponding to 60\%, 45\% of Crab Nebula flux. Variation analysis reveals the variability time-scale of days at the TeV energy band. A simple test by one-zone synchrotron self-Compton model reproduces the data in the gamma-ray band well., Comment: 11 pages, 8 figures, 3 tables

Despite significant advancements in neural text-to-audio generation, challenges persist in controllability and evaluation. This paper addresses these issues through the Sound Scene Synthesis challenge held as part of the Detection and Classification of Acoustic Scenes and Events 2024. We present an evaluation protocol combining objective metric, namely Fr\'echet Audio Distance, with perceptual assessments, utilizing a structured prompt format to enable diverse captions and effective evaluation. Our analysis reveals varying performance across sound categories and model architectures, with larger models generally excelling but innovative lightweight approaches also showing promise. The strong correlation between objective metrics and human ratings validates our evaluation approach. We discuss outcomes in terms of audio quality, controllability, and architectural considerations for text-to-audio synthesizers, providing direction for future research., Comment: accepted to NeurIPS 2024 Workshop: Audio Imagination

Imaging atmospheric Cherenkov telescopes (IACTs) are used to observe very high-energy photons from the ground. Gamma rays are indirectly detected through the Cherenkov light emitted by the air showers they induce. The new generation of experiments, in particular the Cherenkov Telescope Array Observatory (CTAO), sets ambitious goals for discoveries of new gamma-ray sources and precise measurements of the already discovered ones. To achieve these goals, both hardware and data analysis must employ cutting-edge techniques. This also applies to the LST-1, the first IACT built for the CTAO, which is currently taking data on the Canary island of La Palma. This paper introduces a new event reconstruction technique for IACT data, aiming to improve the image reconstruction quality and the discrimination between the signal and the background from misidentified hadrons and electrons. The technique models the development of the extensive air shower signal, recorded as a waveform per pixel, seen by CTAO telescopes' cameras. Model parameters are subsequently passed to random forest regressors and classifiers to extract information on the primary particle. The new reconstruction was applied to simulated data and to data from observations of the Crab Nebula performed by the LST-1. The event reconstruction method presented here shows promising performance improvements. The angular and energy resolution, and the sensitivity, are improved by 10 to 20% over most of the energy range. At low energy, improvements reach up to 22%, 47%, and 50%, respectively. A future extension of the method to stereoscopic analysis for telescope arrays will be the next important step., Comment: Accepted in A&A

A quantum eigenstate of a classically chaotic system is referred as scarred by an unstable periodic orbit if its probability density is concentrated in the vicinity of that orbit. Recently, a new class of scarring - variational scarring - was discovered in numerical studies of disordered quantum dots, arising from near-degeneracies in the quantum spectrum associated with classical resonances of the unperturbed system. Despite the increasing body of theoretical evidence on variational scarring, its experimental observation has remained out of reach. Motivated by this dearth, we argue and demonstrate that variational scarring can occur in an elliptical quantum dot fabricated on monolayer graphene, and locally perturbed by a nanotip. Then, we further show that the fingerprint of these variational scars can potentially be detected via scanning tunneling microscopy, thus offering an attractive experimental pathway for the first validation of this puzzling quantum-chaotic phenomenon.

The NOvA collaboration reports cross-section measurements for $\nu_{\mu}$ charged-current interactions with low hadronic energy (maximum kinetic energy of 250 MeV for protons and 175 MeV for pions) in the NOvA Near Detector. The results are presented as a double-differential cross section as a function of the direct observables of the final-state muon kinematics. Results are also presented as a single-differential cross section as a function of the derived square of the four-momentum transfer, $Q^{2}$, and as a function of the derived neutrino energy. The data correspond to an accumulated 8.09$\times10^{20}$ protons-on-target (POT) in the neutrino mode of the NuMI beam, with a narrow band of neutrino energies peaked at 1.8 GeV. The analysis provides a sample of neutrino-nucleus interactions with an enhanced fraction of quasi-elastic and two-particle-two-hole (2p2h) interactions. This enhancement allows quantitative comparisons with various nuclear models. We find strong disagreement between data and theory-based models in various regions of the muon kinematic phase space, especially in the forward muon direction., Comment: 20 pages, 12 figures. The second version includes an additional citation and adds four previously missing authors

Regression analysis of non-normal correlated data is commonly performed using generalized linear mixed models (GLMM) and generalized estimating equations (GEE). The recent development of generalized joint regression models (GJRM) presents an alternative to these approaches by using copulas to flexibly model response variables and their dependence structures. This paper provides a simulation study that compares the GJRM with alternative methods. We focus on the case of the marginal distributions having the same form, for example, in models for longitudinal data. We find that for the normal model with identity link, all models provide accurate estimates of the parameters of interest. However, for non-normal models and when a non-identity link function is used, GLMMs in general provide biased estimates of marginal model parameters with inaccurately low standard errors. GLMM bias is more pronounced when the marginal distributions are more skewed or highly correlated. However, in the case that a GLMM parameter is estimated independently of the random effect term, we show it is possible to extract accurate parameter estimates, shown for a longitudinal time parameter with a logarithmic link model. In contrast, we find that GJRM and GEE provide unbiased estimates for all parameters with accurate standard errors when using a logarithmic link. In addition, we show that GJRM provides a model fit comparable to GLMM. In a real-world study of doctor visits, we further demonstrate that the GJRM provides better model fits than a comparable GEE or GLM, due to its greater flexibility in choice of marginal distribution and copula fit to dependence structures. We conclude that the GJRM provides a superior approach to current popular models for analysis of non-normal correlated data.

Double- and single-differential cross sections for inclusive charged-current neutrino-nucleus scattering are reported for the kinematic domain 0 to 2 GeV/c in three-momentum transfer and 0 to 2 GeV in available energy, at a mean muon-neutrino energy of 1.86 GeV. The measurements are based on an estimated 995,760 muon-neutrino CC interactions in the scintillator medium of the NOvA Near Detector. The subdomain populated by 2-particle-2-hole reactions is identified by the cross-section excess relative to predictions for neutrino-nucleus scattering that are constrained by a data control sample. Models for 2-particle-2- hole processes are rated by chi-square comparisons of the predicted-versus-measured muon-neutrino CC inclusive cross section over the full phase space and in the restricted subdomain. Shortfalls are observed in neutrino generator predictions obtained using the theory-based Val`encia and SuSAv2 2p2h models., Comment: 20 pages, 14 figures

In this paper we show for every sufficiently large integer $g$ the existence of a complete family of closed and embedded constant mean curvature (CMC) surfaces deforming the Lawson surfaces $\xi_{1,g}$ parametrized by their conformal type. When specializing to the minimal case, we discover a pattern resulting in the coefficients of the involved expansions being alternating multiple zeta values (MZVs), which generalizes the notion of Riemann's zeta values to multiple integer variables. This allows us to extend a new existence proof of the Lawson surfaces $\xi_{1,g}$ to all $g\geq 3$ using complex analytic methods and to give closed form expressions of their area expansion up to order $7$. For example, the third order coefficient is $\tfrac{9}{4}\zeta(3)$ (the first and second order term were shown to be $\log(2)$ and $0$ respectively in \cite{HHT}). As a corollary, we obtain that the area of $\xi_{1,g}$ is monotonically increasing in their genus $g$ for all $g\geq 0.$, Comment: 85 pages, 13 figures, 4 appendices. Includes ancillary Mathematica files verifying calculations. This paper supersedes arXiv:2108.10214

SST-1M is a prototype of a single-mirror Small Size Telescope developed by a consortium of institutes from Poland, Switzerland and the Czech Republic. With a wide field of view of 9 degrees, SST-1Ms are designed to detect gamma-rays in the energy range between 1 and 300 TeV. The design of the SST-1M follows the Davies-Cotton concept, with a 9.42m2 multi-segment mirror. SST-1M is equipped with DigiCam camera, which features a fully digital readout and trigger system using 250 MHz ADC, and a compact Photo-Detector Plane (PDP) composed of 1296 pixels, each made of a hexagonal light guide coupled to silicone photomultipliers (SiPM). Two SST-1M telescopes are currently being commissioned at the Ondrejov Observatory in the Czech Republic, where they are successfully observing Cerenkov events in stereo. This contribution will present an overview of calibration strategies and performance evaluation based on data collected at the observatory., Comment: Volume 444 - 38th International Cosmic Ray Conference (ICRC2023)

The SST-1M is a Small-Sized Telescope (SST) designed to provide a cost-effective and high-performance solution for gamma-ray astrophysics, particularly for energies beyond a few TeV. The goal is to integrate this telescope into an array of similar instruments, leveraging its lightweight design, earthquake resistance, and established Davies-Cotton configuration. Additionally, its optical system is designed to function without a protective dome, allowing it to withstand the harsh atmospheric conditions typical of mountain environments above 2000 m. The SST-1M utilizes a fully digitizing camera system based on silicon photomultipliers (SiPMs). This camera is capable of digitizing all signals from the UV-optical light detectors, allowing for the implementation of various triggers and data analysis methods. We detail the process of designing, prototyping, and validating this system, ensuring that it meets the stringent requirements for gamma-ray detection and performance. An SST-1M stereo system is currently operational and collecting data at the Ond\v{r}ejov observatory in the Czech Republic, situated at 500 m. Preliminary results from this system are promising. A forthcoming paper will provide a comprehensive analysis of the performance of the telescopes in detecting gamma rays and operating under real-world conditions., Comment: 28 pages, 45 figures, 9 tables, to be sumitted to JCAP

Quantum scars refer to eigenstates with enhanced probability density along unstable classical periodic orbits (POs). First predicted 40 years ago, scars are special eigenstates that counterintuitively defy ergodicity in quantum systems whose classical counterpart is chaotic. Despite the importance and long history of scars, their direct visualization in quantum systems remains an open field. Here we demonstrate that, by using an in-situ graphene quantum dot (GQD) creation and wavefunction mapping technique, quantum scars are imaged for Dirac electrons with nanometer spatial resolution and meV energy resolution with a scanning tunneling microscope. Specifically, we find enhanced probability densities in the form of lemniscate-shaped and streak-like patterns within our stadium-shaped GQDs. Both features show equal energy interval recurrence, consistent with predictions for relativistic quantum scars. By combining classical and quantum simulations, we demonstrate that the observed patterns correspond to two unstable POs that exist in our stadium-shaped GQD, thus proving they are both quantum scars. In addition to providing the first unequivocal visual evidence of quantum scarring, our work offers insight into the quantum-classical correspondence in relativistic chaotic quantum systems and paves the way to experimental investigation of other recently proposed scarring species such as perturbation-induced scars, chiral scars, and antiscarring.

While large language models (LLMs) have shown promise for medical question answering, there is limited work focused on tropical and infectious disease-specific exploration. We build on an opensource tropical and infectious diseases (TRINDs) dataset, expanding it to include demographic and semantic clinical and consumer augmentations yielding 11000+ prompts. We evaluate LLM performance on these, comparing generalist and medical LLMs, as well as LLM outcomes to human experts. We demonstrate through systematic experimentation, the benefit of contextual information such as demographics, location, gender, risk factors for optimal LLM response. Finally we develop a prototype of TRINDs-LM, a research tool that provides a playground to navigate how context impacts LLM outputs for health.

Artificial Intelligence (AI) for health has the potential to significantly change and improve healthcare. However in most African countries, identifying culturally and contextually attuned approaches for deploying these solutions is not well understood. To bridge this gap, we conduct a qualitative study to investigate the best practices, fairness indicators, and potential biases to mitigate when deploying AI for health in African countries, as well as explore opportunities where artificial intelligence could make a positive impact in health. We used a mixed methods approach combining in-depth interviews (IDIs) and surveys. We conduct 1.5-2 hour long IDIs with 50 experts in health, policy, and AI across 17 countries, and through an inductive approach we conduct a qualitative thematic analysis on expert IDI responses. We administer a blinded 30-minute survey with case studies to 672 general population participants across 5 countries in Africa and analyze responses on quantitative scales, statistically comparing responses by country, age, gender, and level of familiarity with AI. We thematically summarize open-ended responses from surveys. Our results find generally positive attitudes, high levels of trust, accompanied by moderate levels of concern among general population participants for AI usage for health in Africa. This contrasts with expert responses, where major themes revolved around trust/mistrust, ethical concerns, and systemic barriers to integration, among others. This work presents the first-of-its-kind qualitative research study of the potential of AI for health in Africa from an algorithmic fairness angle, with perspectives from both experts and the general population. We hope that this work guides policymakers and drives home the need for further research and the inclusion of general population perspectives in decision-making around AI usage., Comment: added illustrative figures

Transiting planets around young stars are hard to find due to the enhanced stellar activity. Only a few transiting planets have been detected around stars younger than 100 Myr. We initially detected a transit-like signal in the K2 light curve of a very cool M dwarf star (EPIC 211101996) in the Pleiades open cluster, with an estimated age of about 100 Myr. Our detailed analysis of the per-pixel light curves, detrending with the W\={o}tan software and transit search with the Transit Least Squares algorithm showed that the source of the signal is a contaminant source (Gaia DR3 66767847894609792) 20" west of the target. The V-like shape of its phase-folded light curve and eclipse depth of ~15% suggest that it is a grazing eclipsing binary. The contaminant has hitherto been listed as a single star, which we now identify as an eclipsing stellar binary with a period of about 6 days., Comment: published in RNAAS, Aug. 2024, Vol. 8, No. 8, 3 pages, 1 col. Figure

Analytic continuations of holographic entanglement entropy in which the boundary subregion extends along a timelike direction have brought a promise of a novel, time-centric probe of the emergence of spacetime. We propose that the bulk carriers of this holographic timelike entanglement entropy are boundary-anchored extremal surfaces probing analytic continuation of holographic spacetimes into complex coordinates. This proposal not only provides a geometric interpretation of all the known cases obtained by direct analytic continuation of closed-form expressions of holographic entanglement entropy of a strip subregion but crucially also opens a window to study holographic timelike entanglement entropy in full generality. We initialize the investigation of complex extremal surfaces anchored on a timelike strip at the boundary of anti-de Sitter black branes. We find multiple complex extremal surfaces and discuss possible principles singling out the physical contribution., Comment: 8 pages, 6 figures

Survival is poor for patients with metastatic cancer, and it is vital to examine new biomarkers that can improve patient prognostication and identify those who would benefit from more aggressive therapy. In metastatic prostate cancer, two new assays have become available: one that quantifies the number of cancer cells circulating in the peripheral blood, and the other a marker of the aggressiveness of the disease. It is critical to determine the magnitude of the effect of these biomarkers on the discrimination of a model-based risk score. To do so, most analysts frequently consider the discrimination of two separate survival models: one that includes both the new and standard factors and a second that includes the standard factors alone. However, this analysis is ultimately incorrect for many of the scale-transformation models ubiquitous in survival, as the reduced model is misspecified if the full model is specified correctly. To circumvent this issue, we developed a projection-based approach to estimate the impact of the two prostate cancer biomarkers. The results indicate that the new biomarkers can influence model discrimination and justify their inclusion in the risk model; however, the hunt remains for an applicable model to risk-stratify patients with metastatic prostate cancer.

The 23 Myr young star $\beta$ Pictoris is a laboratory for planet formation studies given its observed debris disk, its two directly imaged super-Jovian planets, and the evidence of transiting extrasolar comets. The most recent evidence of exocometary transits around $\beta$ Pic came from the TESS space mission. Previous analyses of these transits constrained the orbital distribution of the underlying exocomet population to range between about 0.03 and 1.3 AU assuming a fixed transit impact parameter. Here we examine the distribution of the observed transit durations (${\Delta}t$) to infer the orbital surface density distribution ($\delta$) of the underlying exocomet sample. We show that a narrow belt of exocomets around $\beta$ Pic, in which the transit impact parameters are randomized but the orbital semimajor axes are equal, results in a pile-up of long transit durations. This is contrary to observations, which reveal a pile-up of short transit durations (${\Delta}t \approx 0.1$ d) and a tail of only a few transits with ${\Delta}t > 0.4$ d. A flat density distribution of exocomets between about 0.03 and 2.5 AU results in a better match between the resulting ${\Delta}t$ distribution and the observations but the slope of the predicted ${\Delta}t$ histogram is not sufficiently steep. An even better match to the observations can be produced with a $\delta \propto a^{\beta}$ power law. Our modeling reveals a best fit between the observed and predicted ${\Delta}t$ distribution for $\beta = -0.15_{-0.10}^{+0.05}$. A more reasonable scenario in which the exocometary trajectories are modeled as hyperbolic orbits can also reproduce the observed ${\Delta}t$ distribution to some extent. Our results imply that cometary material exists on highly eccentric orbits with a more extended range of semimajor axes than suggested by previous spectroscopic observations., Comment: accepted in Astronomy & Astrophysics, 6 pages, 7 Figures (6 col., 1 b/w)

Neutron scattering experiments have played vital roles in exploring materials properties in the past decades. While user interfaces have been improved over time, neutron scattering experiments still require specific knowledge or training by an expert due to the complexity of such advanced instrumentation and the limited number of experiments each person may perform each year. This paper introduces an innovative chatbot application that leverages Large Language Models(LLM) and Retrieval-Augmented Generation (RAG) technologies to significantly enhance the user experience at the EQ-SANS, a small-angle neutron scattering instrument at the Spallation Neutron Source of Oak Ridge National Laboratory. Through a user-centric design approach, the EQ-SANS Assisting Chatbot (ESAC) serves as an interactive reference for users, thereby facilitating the use of the instrument by visiting scientists. By bridging the gap between the users of EQ-SANS and the control systems required to perform their experiments, the ESAC sets a new standard for interactive learning and support for the scientific community using large-scale scientific facilities.

This paper does not describe a novel method. Instead, it studies an essential foundation for reliable benchmarking and ultimately real-world application of AI-based image analysis: generating high-quality reference annotations. Previous research has focused on crowdsourcing as a means of outsourcing annotations. However, little attention has so far been given to annotation companies, specifically regarding their internal quality assurance (QA) processes. Therefore, our aim is to evaluate the influence of QA employed by annotation companies on annotation quality and devise methodologies for maximizing data annotation efficacy. Based on a total of 57,648 instance segmented images obtained from a total of 924 annotators and 34 QA workers from four annotation companies and Amazon Mechanical Turk (MTurk), we derived the following insights: (1) Annotation companies perform better both in terms of quantity and quality compared to the widely used platform MTurk. (2) Annotation companies' internal QA only provides marginal improvements, if any. However, improving labeling instructions instead of investing in QA can substantially boost annotation performance. (3) The benefit of internal QA depends on specific image characteristics. Our work could enable researchers to derive substantially more value from a fixed annotation budget and change the way annotation companies conduct internal QA., Comment: Accepted at ECCV 2024, preprint, Computer Vision, Data Annotation

We present the results of an extensive evaluation of strip and pixel AC-LGAD sensors tested with a 120 GeV proton beam, focusing on the influence of design parameters on the sensor temporal and spatial resolutions. Results show that reducing the thickness of pixel sensors significantly enhances their time resolution, with 20 $\mu$m-thick sensors achieving around 20 ps. Uniform performance is attainable with optimized sheet resistance, making these sensors ideal for future timing detectors. Conversely, 20 $\mu$m-thick strip sensors exhibit higher jitter than similar pixel sensors, negatively impacting time resolution, despite reduced Landau fluctuations with respect to the 50 $\mu$m-thick versions. Additionally, it is observed that a low resistivity in strip sensors limits signal size and time resolution, whereas higher resistivity improves performance. This study highlights the importance of tuning the n$^{+}$ sheet resistance and suggests that further improvements should target specific applications like the Electron-Ion Collider or other future collider experiments. In addition, the detailed performance of four AC-LGADs sensor designs is reported as examples of possible candidates for specific detector applications. These advancements position AC-LGADs as promising candidates for future 4D tracking systems, pending the development of specialized readout electronics.

Context: There are currently three pulsars firmly detected by imaging atmospheric Cherenkov telescopes (IACTs), two of them reaching TeV energies, challenging models of very-high-energy (VHE) emission in pulsars. More precise observations are needed to better characterize pulsar emission at these energies. The LST-1 is the prototype of the Large-Sized Telescope, that will be part of the Cherenkov Telescope Array Observatory (CTAO). Its improved performance over previous IACTs makes it well suited for studying pulsars. Aims: To study the Crab pulsar emission with the LST-1, improving and complementing the results from other telescopes. These observations can also be used to characterize the potential of the LST-1 to study other pulsars and detect new ones. Methods: We analyzed a total of $\sim$103 hours of gamma-ray observations of the Crab pulsar conducted with the LST-1 in the period from September 2020 to January 2023. The observations were carried out at zenith angles less than 50 degrees. A new analysis of the Fermi-LAT data was also performed, including $\sim$14 years of observations. Results: The Crab pulsar phaseogram, long-term light-curve, and phase-resolved spectra are reconstructed with the LST-1 from 20 GeV to 450 GeV for P1 and up to 700 GeV for P2. The pulsed emission is detected with a significance of 15.2$\sigma$. The two characteristic emission peaks of the Crab pulsar are clearly detected (>10$\sigma$), as well as the so-called bridge emission (5.7$\sigma$). We find that both peaks are well described by power laws, with spectral indices of $\sim$3.44 and $\sim$3.03 respectively. The joint analysis of Fermi-LAT and LST-1 data shows a good agreement between both instruments in the overlapping energy range. The detailed results obtained in the first observations of the Crab pulsar with LST-1 show the potential that CTAO will have to study this type of sources., Comment: Accepted by A&A

TICAS partnered with higher education researcher Dr. Donald E. Heller to examine the "affordability gap" that students are facing when paying for college. The report uses federal data to determine the so-called "college affordability gap" in three states--California, Michigan, and New York--with a focus on students who are eligible for the federal Pell Grant. The affordability gap is defined in this analysis as the gap between a student's total costs of attending college--including tuition, fees, housing, food, and other expenses--and the amount of non-loan aid available to them: a combination of family resources, grant aid, and earnings from a reasonable number of work hours. The report then examines how much the example states would need to invest close this gap for Pell-eligible students, with the goal of a $0 gap for such students. This analysis builds on TICAS' ongoing efforts to build a debt-free future for all students.

Kidney cancer is a global health concern, and accurate assessment of patient frailty is crucial for optimizing surgical outcomes. This paper introduces AI Age Discrepancy, a novel metric derived from machine learning analysis of preoperative abdominal CT scans, as a potential indicator of frailty and postoperative risk in kidney cancer patients. This retrospective study of 599 patients from the 2023 Kidney Tumor Segmentation (KiTS) challenge dataset found that a higher AI Age Discrepancy is significantly associated with longer hospital stays and lower overall survival rates, independent of established factors. This suggests that AI Age Discrepancy may provide valuable insights into patient frailty and could thus inform clinical decision-making in kidney cancer treatment., Comment: 10 pages, 3 figures, 2 tables

To understand how martensitic transformation (MT) in polycrystalline NiTi shape memory alloy (SMA) proceeds under external stress, we evaluated recoverable transformation strains and plastic strains generated by the forward MT in nanocrystalline NiTi wire cooled under tensile stresses 0-600 MPa, determined textures in martensite and reconstructed martensite variant microstructures within the selected grains of the cooled wire. The obtained findings show that the forward MT proceeding under external stresses gives rise to characteristic recoverable transformation strains, plastic strains, martensite variant microstructures and martensite textures. MT occurring upon cooling under stresses exceeding 100 MPa creates martensite variant microstructures consisting of single domain of partially detwinned laminate of (001) compound twins filling entire grains. The recoverable transformation strain increases with increasing stress, reaches maximum ~5% at ~200 MPa stress, and remains constant with further increasing stress up to 600 MPa. Starting from 100 MPa stress, the forward MT generates also plastic strains, the magnitude of which also increases with increasing stress. We propose that, in the absence of external stress, the forward MT takes place via propagation of strain compatible habit plane interfaces between austenite and second order laminate of (001) compound twins. When the forward MT takes place under external tensile stress, it occurs equally, but the newly created martensite immediately reorients into single domains of (001) compound twins, partially detwins and deforms plastically under the action of the external stress. The plastic strain generated by the forward MT upon cooling under stress is attributed to the [100](001) dislocation slip in martensite at low stresses and plastic deformation of martensite by kwinking at high stresses., Comment: 35 pages, 15 figures

Superelastic NiTi 1 shape memory alloy (SMA) wire was subjected to thermomechanical loading tests in tension to evaluate stress and temperature conditions under which the wire deforms plastically. Although the alloy demonstrated a very high resistance to plastic deformation in both the austenite and martensite phases, incremental plastic strains were recorded whenever the B2 cubic to B19' monoclinic martensitic transformation (MT) took place under external stress. To shed light on the origin of the functional fatigue presumably originating from the accumulated plastic strains, special closed-loop thermomechanical loading tests were performed to evaluate recoverable and plastic strains generated by the forward and reverse MTs under external stress. These experiments revealed that both forward and reverse MTs generate well-defined incremental plastic strains only if they occur above certain stress thresholds. Specifically, the forward MT upon cooling under stresses up to 500 MPa does not produce plastic strain or lattice defects, whereas the reverse MT upon heating generates plastic strains even under stress as low as 100 MPa. It is proposed that plastic deformation generated by martensitic transformations under low stresses takes place by [100](001) dislocation slip in martensite and while under high stresses it occurs via kwinking deformation in martensite. The characteristic thresholds and magnitudes of plastic strains generated by the forward and reverse MTs define the functional fatigue limits for NiTi. Specifically, the stress-strain-temperature responses recorded in closed-loop thermomechanical tests remain stable if both forward and reverse MTs occur below these thresholds. Conversely, they become unstable and exhibit predictable ratcheting if the MTs exceed these thresholds., Comment: 37 pages, 14 figures

Functional behavior of NiTi shape memory alloys is restricted to temperatures below 150 {\deg}C. To shed light on the origin of the loss of functional properties of NiTi with increasing temperature, we have investigated stress induced martensitic transformations in nanocrystalline NiTi shape memory wire by thermomechanical testing supplemented with post-mortem reconstruction of martensite variant microstructures in grains by transmission electron microscopy. It was found that the forward stress induced martensitic transformation proceeding via propagation of macroscopic Luders band fronts in stress plateaus is not completed at the end of the stress plateau and generates unrecoverable plastic strain in addition to recoverable transformation strain. The higher the test temperature, the larger is the plastic strain as well as the volume fraction of retained austenite. The reconstructed martensite variant microstructures in grains of the NiTi wire deformed up to the end of the stress plateau at 120 {\deg}C were found to be filled with single domains of (001) compound twin laminate, some grains were nearly detwinned and some grains contained (100) deformation twins. The recoverable transformation strain (~6%) generated by the forward martensitic transformation is nearly independent on the test temperature (plateau stress) because detwinning of (001) compound twins in the microstructure is prohibited by lateral constraint from the surrounding grains in nanocrystalline wire. It is concluded that the gradual loss of functionality of NiTi with increasing temperature does not originate from the plastic deformation of austenite, but that it derives from the lack of resistance of the stress induced martensite to the plastic deformation under increasing stress., Comment: 35 pages, 19 figures

We study compact minimal surfaces in the 3-sphere which are constructed by successive reflections from a minimal $n$-gon -- so-called minimal reflection surfaces. The minimal $n$-gon solves a free boundary problem in a fundamental piece of the respective reflection group. We investigate the combinatorics of the curvature lines of reflection surfaces, and construct new examples of minimal reflection surfaces based on pentagons. We end the paper by discussing the area of these minimal surfaces., Comment: 32 pages, 9 figures

Ge1-xSnx and Si1-x-yGeySnx alloys are promising materials for future opto- and nanoelectronics applications. These alloys enable effective band-gap engineering, broad adjustability of their lattice parameter, exhibit much higher carrier mobility than pure Si, and are compatible with the CMOS technology. Unfortunately, the equilibrium solid solubility of Sn in Si1-xGex is less than 1% and the pseudomorphic growth of Si1-x-yGeySnx on Ge or Si can cause in-plane compressive strain in the grown layer, degrading the superior properties of these alloys. Therefore, post-growth strain engineering by ultrafast non-equilibrium thermal treatments like pulse laser annealing (PLA) is needed to improve the layer quality. In this article, Ge0.94Sn0.06 and Si0.14Ge0.8Sn0.06 thin films grown on silicon-on-insulator substrates by molecular beam epitaxy were post growth thermally treated by PLA. The material is analyzed before and after the thermal treatments by transmission electron microscopy, X-ray diffraction (XRD), Rutherford backscattering spectrometry, secondary ion mass spectrometry, and Hall effect measurements. It is shown that after annealing, the material is single-crystalline with improved crystallinity than the as-grown layer. This is reflected in a significantly increased XRD reflection intensity, well-ordered atomic pillars, and increased active carrier concentrations up to 4x1019 cm-3.

In this work we try to search for signals generated by ultra-heavy dark matter at the Large High Altitude Air Shower Observatory (LHAASO) data. We look for possible gamma-ray by dark matter annihilation or decay from 16 dwarf spheroidal galaxies in the field of view of LHAASO. Dwarf spheroidal galaxies are among the most promising targets for indirect detection of dark matter which have low fluxes of astrophysical $\gamma$-ray background while large amount of dark matter. By analyzing more than 700 days observational data at LHAASO, no significant dark matter signal from 1 TeV to 1 EeV is detected. Accordingly we derive the most stringent constraints on the ultra-heavy dark matter annihilation cross-section up to EeV. The constraints on the lifetime of dark matter in decay mode are also derived., Comment: 17 pages, 12 figures, accepted by PRL

Using numerical simulations of barred disk galaxy embedded in nonspinning and spinning dark matter (DM) halos, we present a novel mechanism of `cooling' the vertical oscillations of DM particles, which acquire the disk kinematics. The underlying mechanism consists of resonant interactions between halo particles and the stellar bar, facilitated by chaotic phase space of the system. The cooling mechanism acts both on dynamical and secular timescales, from $\sim 0.5$\,Gyr to few Gyr. The stellar bar acts to absorb kinetic energy of the vertical motions. Using Milky Way-type stellar halo, we estimate the population of metal-poor disk stars trapped by the MW disk and analyze its kinematics. We find that population of metal-poor MW disk stars with $|z|\ltorder 3$\,kpc detected by the Gaia DR3 and other surveys can have their origin in the stellar halo. The cooled population also migrates radially outwards by exchanging energy and angular momentum with the spinning bar, and prograde-moving stars have a different distribution from the retrograde ones. Next, we have calculated the ratio of the prograde-to-retrograde orbits of the cooled population and found that this ratio varies radially, with the fast-spinning stellar halo resulting in the shallower radial increase of this ratio outside of the corotation. The nonspinning stellar halo shows a monotonic increase of this ratio with radius outside the corotation. Together with analyzed radial migration of these halo stars, the cooling phenomenon of halo metal-poor stars can explain their current disk population, and has corollaries for chemical evolution of disk galaxies in general., Comment: 13 pages, 9 figures, 1 table. A shortened version has been accepted by ApJ Letters

PLATO (PLAnetary Transits and Oscillations of stars) is ESA's M3 mission designed to detect and characterise extrasolar planets and perform asteroseismic monitoring of a large number of stars. PLATO will detect small planets (down to <2 R_(Earth)) around bright stars (<11 mag), including terrestrial planets in the habitable zone of solar-like stars. With the complement of radial velocity observations from the ground, planets will be characterised for their radius, mass, and age with high accuracy (5 %, 10 %, 10 % for an Earth-Sun combination respectively). PLATO will provide us with a large-scale catalogue of well-characterised small planets up to intermediate orbital periods, relevant for a meaningful comparison to planet formation theories and to better understand planet evolution. It will make possible comparative exoplanetology to place our Solar System planets in a broader context. In parallel, PLATO will study (host) stars using asteroseismology, allowing us to determine the stellar properties with high accuracy, substantially enhancing our knowledge of stellar structure and evolution. The payload instrument consists of 26 cameras with 12cm aperture each. For at least four years, the mission will perform high-precision photometric measurements. Here we review the science objectives, present PLATO's target samples and fields, provide an overview of expected core science performance as well as a description of the instrument and the mission profile at the beginning of the serial production of the flight cameras. PLATO is scheduled for a launch date end 2026. This overview therefore provides a summary of the mission to the community in preparation of the upcoming operational phases.

INTRODUCTION: The pharmacological treatment of Major Depressive Disorder (MDD) relies on a trial-and-error approach. We introduce an artificial intelligence (AI) model aiming to personalize treatment and improve outcomes, which was deployed in the Artificial Intelligence in Depression Medication Enhancement (AIDME) Study. OBJECTIVES: 1) Develop a model capable of predicting probabilities of remission across multiple pharmacological treatments for adults with at least moderate major depression. 2) Validate model predictions and examine them for amplification of harmful biases. METHODS: Data from previous clinical trials of antidepressant medications were standardized into a common framework and included 9,042 adults with moderate to severe major depression. Feature selection retained 25 clinical and demographic variables. Using Bayesian optimization, a deep learning model was trained on the training set, refined using the validation set, and tested once on the held-out test set. RESULTS: In the evaluation on the held-out test set, the model demonstrated achieved an AUC of 0.65. The model outperformed a null model on the test set (p = 0.01). The model demonstrated clinical utility, achieving an absolute improvement in population remission rate in hypothetical and actual improvement testing. While the model did identify one drug (escitalopram) as generally outperforming the other drugs (consistent with the input data), there was otherwise significant variation in drug rankings. On bias testing, the model did not amplify potentially harmful biases. CONCLUSIONS: We demonstrate the first model capable of predicting outcomes for 10 different treatment options for patients with MDD, intended to be used at or near the start of treatment to personalize treatment. The model was put into clinical practice during the AIDME randomized controlled trial whose results are reported separately.

The TEMPO (Transiting Exosatellites, Moons, and Planets in Orion) Survey is a proposed 30-day observational campaign using the Nancy Grace Roman Space Telescope. By providing deep, high-resolution, short-cadence infrared photometry of a dynamic star-forming region, TEMPO will investigate the demographics of exosatellites orbiting free-floating planets and brown dwarfs -- a largely unexplored discovery space. Here, we present the simulated detection yields of three populations: extrasolar moon analogs orbiting free-floating planets, exosatellites orbiting brown dwarfs, and exoplanets orbiting young stars. Additionally, we outline a comprehensive range of anticipated scientific outcomes accompanying such a survey. These science drivers include: obtaining observational constraints to test prevailing theories of moon, planet, and star formation; directly detecting widely separated exoplanets orbiting young stars; investigating the variability of young stars and brown dwarfs; constraining the low-mass end of the stellar initial mass function; constructing the distribution of dust in the Orion Nebula and mapping evolution in the near-infrared extinction law; mapping emission features that trace the shocked gas in the region; constructing a dynamical map of Orion members using proper motions; and searching for extragalactic sources and transients via deep extragalactic observations reaching a limiting magnitude of $m_{AB}=29.7$\,mag (F146 filter)., Comment: 15 pages, 6 figures, submitted to OJAp

Stars with about 45 to 80% the mass of the Sun, so-called K dwarf stars, have previously been proposed as optimal host stars in the search for habitable extrasolar worlds. These stars are abundant, have stable luminosities over billions of years longer than Sun-like stars, and offer favorable space environmental conditions. So far, the theoretical and experimental focus on exoplanet habitability has been on even less massive, though potentially less hospitable red dwarf stars. Here we present the first experimental data on the responses of photosynthetic organisms to a simulated K dwarf spectrum. We find that garden cress Lepidium sativum under K-dwarf radiation exhibits comparable growth and photosynthetic efficiency as under solar illumination on Earth. The cyanobacterium Chroococcidiopsis sp. CCMEE 029 exhibits significantly higher photosynthetic efficiency and culture growth under K dwarf radiation compared to solar conditions. Our findings of the affirmative responses of these two photosynthetic organisms to K dwarf radiation suggest that exoplanets in the habitable zones around such stars deserve high priority in the search for extrasolar life.

The intricate relationship between electrons and the crystal lattice is a linchpin in condensed matter, traditionally described by the Fr\"ohlich model encompassing the lowest-order lattice-electron coupling. Recently developed quantum acoustics, emphasizing the wave nature of lattice vibrations, has enabled the exploration of previously uncharted territories of electron-lattice interaction not accessible with conventional tools such as perturbation theory. In this context, our agenda here is two-fold. First, we showcase the application of machine learning methods to categorize various interaction regimes within the subtle interplay of electrons and the dynamical lattice landscape. Second, we shed light on a nebulous region of electron dynamics identified by the machine learning approach and then attribute it to transient localization, where strong lattice vibrations result in a momentary Anderson prison for electronic wavepackets, which are later released by the evolution of the lattice. Overall, our research illuminates the spectrum of dynamics within the Fr\"ohlich model, such as transient localization, which has been suggested as a pivotal factor contributing to the mysteries surrounding strange metals. Furthermore, this paves the way for utilizing time-dependent perspectives in machine learning techniques for designing materials with tailored electron-lattice properties., Comment: 14 pages, 9 figures

The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy was the construction of an observatory capable of characterizing habitable worlds. In this paper series we explore the detectability of and interference from exomoons and exorings serendipitously observed with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every star-planet-moon system. The cadence of these events can vary widely from ~yearly to multiple events per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI) lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable with observation of ~2-20 mutual events for systems within 10pc, and larger moons should remain detectable out to 20pc. We explore the extent to which exomoon mutual events can mimic planet features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 micron water band where large moons can outshine their host planet, will aid in differentiating exomoon signals from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin to our Moon are more likely to be detected in younger systems, where shorter orbital periods and favorable geometry enhance the probability and frequency of mutual events., Comment: 16 pages, 11 figures, in review at AJ, includes revisions from first round of review, comments welcome

Recent theoretical investigations have revealed unconventional transport mechanisms within high Brilliouin zones of two-dimensional superlattices. Electrons can navigate along channels we call superwires, gently guided without brute force confinement. Such dynamical confinement is caused by weak superlattice deflections, markedly different from the static or energetic confinement observed in traditional wave guides or one-dimensional electron wires. The quantum properties of superwires give rise to elastic dynamical tunneling, linking disjoint regions of the corresponding classical phase space, and enabling the emergence of several parallel channels. This paper provides the underlying theory and mechanisms that facilitate dynamical tunneling assisted by chaos in periodic lattices. Moreover, we show that the mechanism of dynamical tunneling can be effectively conceptualized through the lens of a paraxial approximation. Our results further reveal that superwires predominantly exist within flat bands, emerging from eigenstates that represent linear combinations of conventional degenerate Bloch states. Finally, we quantify tunneling rates across various lattice configurations, and demonstrate the tunneling can be suppressed in a controlled fashion, illustrating potential implications in future nanodevices., Comment: 12 pages, 6 Figures

Generating indistinguishable photons from independent nodes is an important challenge for the development of quantum networks. In this work, we demonstrate the generation of highly indistinguishable single photons from two dissimilar atomic quantum nodes. One node is based on a fully blockaded cold Rydberg ensemble and generates on-demand single photons. The other node is a quantum repeater node based on a DLCZ quantum memory and emits heralded single photons after a controllable memory time that is used to synchronize the two sources. We demonstrate an indistinguishability of ${94.6 \pm 5.2 \%}$ for a temporal window including ${90\%}$ of the photons. This advancement opens new possibilities for interconnecting quantum repeater and processing nodes with high fidelity Bell-state measurement without sacrificing its efficiency.

We investigate the impact of attending a free school in England -- that is, a new start-up school that enjoys considerable autonomy while remaining in the state sector. We analyse the effects of two secondary free schools with different teaching philosophies: one follows a 'no excuse' paradigm, while the other one adopts a 'classical liberal', knowledge-rich approach. We establish causal effects exploiting admission lotteries and a distance-based regression discontinuity design. Both schools have a strong positive impact on student test scores on average. However, we also find heterogeneous effects: the 'no excuse' school mostly benefits boys, while the 'classical liberal' school mainly benefits White British and non-poor students. Both schools similarly reduce student absences and school mobility. Peer quality, teacher characteristics, and inspectorate ratings cannot fully explain the schools' effectiveness. Instead, a quantitative text analysis of the schools' 'vision and ethos' statements shows that the 'no excuse' and 'classical liberal' philosophies adopted by the two free schools clearly set them apart from the counterfactual schools where rejected applicants enrol, and likely explain their heterogeneous effects.