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2602.10076 2026-02-11 cond-mat.str-el

Orbital piezomagnetic polarizability of pure insulating altermagnets in two dimensions

Beryl Bell, Jörn W. F. Venderbos

Comments 11 pages; 9 figures; 3 appendices

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The distinctive symmetry properties of pure altermagnets make them natural candidates for piezomagnetism. Previous work motivated by the piezomagnetic properties of altermagnets has primarily focused on the spin magnetization response to applied strain. In this paper we study orbital piezomagnetic effects--the orbital magnetization response to applied strain--in minimal lattice models of pure insulating altermagnets in two dimensions. We obtain general microscopic expressions for the orbital magnetization in the presence of strain, as well as the orbital piezomagnetic polarizability, i.e., the defining response characteristic of pure altermagnets. We apply these expressions to three specific tetragonal lattice models, two corresponding to $d$-wave altermagnets and one describing a $g$-wave altermagnet. Whereas the $d$-wave altermagnets are associated with a linear piezomagnetic polarizability, the $g$-wave altermagnet exhibits a nonlinear piezomagnetic effect. Our analysis reveals how the polarizabilities are related to and determined by the Berry curvature of the occupied bands. Connections to materials of current interest are discussed.

2602.10075 2026-02-11 hep-ph hep-ex hep-lat

Tensor states $ΥB_{c}^{\ast -}$ and $J/ψB_{c}^{\ast +}$

S. S. Agaev, K. Azizi, H. Sundu

Comments 11 Pages, 5 Figures and 1 Table

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Tensor states $\mathcal{M}_{\mathrm{T}}^{\mathrm{b}}=ΥB_{c}^{\ast -}$ and $\mathcal{M}_{\mathrm{T}}^{\mathrm{c}}=J/ψB_{c}^{\ast +}$ are explored using techniques of QCD sum rule method. These hadronic molecules, composed of only heavy quarks, have asymmetric quark contents $bb\overline{b} \overline{c}$ and $cc\overline{c}\overline{b}$, respectively. The masses $ m=(15864 \pm 85)~\mathrm{MeV} $ and $\widetilde{m}=(9870 \pm 82)~\mathrm{MeV} $ prove that these structures are unstable against dissociations to constituent mesons. Full widths of molecules $\mathcal{M}_{\mathrm{T}}^{ \mathrm{b}}$ and $\mathcal{M}_{\mathrm{T}}^{\mathrm{c}}$ are calculated by considering their dominant and subleading decay channels. The subleading channels are processes generated by annihilations of $\overline{b}b$ and $ \overline{c}c$ quarks. For the molecule $\mathcal{M}_{\mathrm{T}}^{\mathrm{b} }$ dominant decays are $\mathcal{M}_{\mathrm{T}}^{\mathrm{b}} \to ΥB_{c}^{\ast -}$ and $\mathcal{M}_{\mathrm{T}}^{\mathrm{b}} \to η_b B_{c}^{-}$, whereas subleading channels are transformations to $\mathcal{M}_{ \mathrm{T}}^{\mathrm{b}}\rightarrow B^{(\ast )-}\overline{D}^{(\ast )0}$ and $\overline{B}_{(s)}^{(\ast )0}D_{(s)}^{(\ast )-}$ mesons. In the case of $ \mathcal{M}_{\mathrm{T}}^{\mathrm{c}}$ we explore decays to $J/ψB_{c}^{\ast +}$, $η_{c}B_{c}^{+}$, $B^{(\ast)+}D^{(\ast )0}$ and $ B_{(s)}^{(\ast )0}D_{(s)}^{(\ast )+}$ mesons. Predictions $Γ[\mathcal{M} _{\mathrm{T}}^{\mathrm{b}}]=120^{+17}_{-12}~ \mathrm{MeV} $ and $Γ[ \mathcal{M}_{\mathrm{T}}^{\mathrm{c}}]=(71 \pm 9)~ \mathrm{MeV} $ for the widths of these molecules characterize them as relatively broad structures.

2602.10073 2026-02-11 cs.CC

Some conditions implying if P=NP then P=PSPACE

Ismael Rodriguez

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We identify a few conditions $X$ such that $(P=NP \wedge X) \;\Rightarrow\; P=PSPACE$.

2602.10072 2026-02-11 astro-ph.GA

SDSS-V Local Volume Mapper (LVM): Helix Nebula public data, Data Analysis Pipeline data products

S. F. Sánchez, J. E. Méndez-Delgado, A. Mejía-Narváez, C. Román-Zuñiga, O. V. Egorov, C. Morisset, N. Drory, G. A. Blanc, K. Kreckel, E. J. Johnston, Ivan Yu. Katkov, A. Roman Lopes, M. A. Villa-Durango, H. Ibarra-Medel, H. -W. Rix, R. de J. Zermeño, J. G. Fernández Trincado, A. Singh, P. García, G. S. Stringfellow, L. Sabin, J. Toalá, R. Orozco Duarte, A. M. Jones

Comments 20 pages, 12 figures, accepted for publishing in RMxA&A

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We present a spatially resolved spectroscopic analysis of the Helix Nebula (NGC 7293) using data from the SDSS-V Local Volume Mapper (LVM), by applying the recently developed LVM Data Analysis Pipeline (LVM-DAP). Covering the full optical range (3600-9800 Å) over a contiguous ~ 0.5 degree field, the LVM data provide the first hexagonally sampled, wide-field emission-line maps of all major ionic species in this archetypal planetary nebula. The resulting flux, kinematic, and line-ratio maps reveal the well-known ionization stratification of the nebula, from the compact He++ core to the bright [O III] ring and the extended low-ionization envelope, enabling a detailed comparison with classical aperture spectroscopy. Owing to the sensitivity and uniform spatial sampling of the LVM, numerous faint auroral and diagnostic lines are detected across the nebula, including [O III] 4363, [N II] 5755, and He I lines, allowing precise measurements of weak-line morphology. The derived radial trends confirm the remarkably low dust content and the overall homogeneity of electron temperature and density across the main ring. Ionized-gas kinematics traced by Hα further support the scenario of a slowly expanding, limb-brightened shell consistent with previous studies. This work demonstrates the diagnostic power of LVM spectroscopy for extended nebulae and highlights its capability to recover both global and spatially resolved physical conditions across complex ionized structures.

2602.10066 2026-02-11 physics.optics

Programmable and nonvolatile computing with composition tuning in thin film lithium niobate

Abhiram Devata, Axel Magaña Ponce, David Barton

Comments 20 pages, 4 figures

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Matrix-vector multiplications are fundamental operations in artificial intelligence and high-throughput computations, and are executed repeatedly during training and inference. Their high energy cost in electronic processors motivate scalable photonic computing approaches that reduce the energy required per operation. Thin film lithium niobate (TFLN) is a dominant photonic platform due to its large electro-optic effect. However, it lacks nonvolatile index tuning mechanisms, which promise to pave the way for energy-efficient photonic computing. Here, we explore electrochemical lithiation as a route to nonvolatile matrix-vector multiplications in TFLN. The LiNbO3 phase is stable at room temperature over a 2% Li composition window with an associated composition-dependent refractive index. We computationally demonstrate this as a programmable, low-loss approach to perform matrix-vector multiplications by using composition to control matrix weights. We design Mach-Zehnder interferometers to perform image processing tasks under realistic material loss constraints. We also design microring resonators for iterative weight updates, using gradient descent training to program target matrix operations with matrix-vector multiplication accuracy validated at 1.5% average relative error. These demonstrations show a facile route towards nonvolatile photonic computing in TFLN, addressing a critical requirement for energy-efficient photonic matrix operations at scale.

2602.10065 2026-02-11 astro-ph.CO

Dark Energy Survey Year 6 Results: Cosmological Constraints from Cosmic Shear

DES Collaboration, T. M. C. Abbott, M. Aguena, A. Alarcon, O. Alves, A. Amon, D. Anbajagane, F. Andrade-Oliveira, W. d'Assignies, S. Avila, D. Bacon, J. Beas-Gonzalez, K. Bechtol, M. R. Becker, G. M. Bernstein, J. Blazek, S. Bocquet, D. Brooks, H. Camacho, G. Camacho-Ciurana, R. Camilleri, G. Campailla, A. Campos, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, F. J. Castander, R. Cawthon, C. Chang, A. Choi, J. M. Coloma-Nadal, C. Conselice, L. N. da Costa, M. Costanzi, M. Crocce, T. M. Davis, J. De Vicente, D. L. DePoy, J. DeRose, S. Desai, H. T. Diehl, P. Doel, C. Doux, A. Drlica-Wagner, T. F. Eifler, S. Everett, A. E. Evrard, A. Ferté, B. Flaugher, P. Fosalba, O. Friedrich, J. Frieman, J. García-Bellido, M. Gatti, G. Giannini, P. Giles, K. Glazebrook, D. Gruen, R. A. Gruendl, G. Gutierrez, I. Harrison, W. G. Hartley, K. Herner, S. R. Hinton, D. L. Hollowood, K. Honscheid, D. Huterer, B. Jain, D. J. James, M. Jarvis, N. Jeffrey, T. Jeltema, T. Kacprzak, S. Kent, E. Krause, O. Lahav, S. Lee, E. Legnani, H. Lin, J. L. Marshall, S. Mau, J. Mena-Fernández, F. Menanteau, R. Miquel, J. J. Mohr, J. Muir, J. Myles, R. C. Nichol, R. L. C. Ogando, A. Palmese, M. Paterno, W. J. Percival, D. Petravick, A. A. Plazas Malagón, A. Porredon, J. Prat, C. Preston, M. Raveri, M. Rodriguez-Monroy, A. K. Romer, A. Roodman, E. S. Rykoff, S. Samuroff, C. Sánchez, E. Sanchez, D. Sanchez Cid, T. Schutt, I. Sevilla-Noarbe, E. Sheldon, T. Shin, M. E. da Silva Pereira, M. Smith, M. Soares-Santos, E. Suchyta, M. E. C. Swanson, M. Tabbutt, G. Tarle, D. Thomas, C. To, M. A. Troxel, V. Vikram, M. Vincenzi, N. Weaverdyck, J. Weller, P. Wiseman, M. Yamamoto, B. Yanny, B. Yin, J. Zuntz

Comments See this https://www.darkenergysurvey.org/des-y6-cosmology-results-papers/ for the full DES Y6 3x2pt cosmology release

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We present legacy cosmic shear measurements and cosmological constraints using six years of Dark Energy Survey imaging data. From these data, we study ~140 million galaxies (8.29 galaxies/arcmin$^2$) that are 50% complete at i=24.0 and extend beyond z=1.2. We divide the galaxies into four redshift bins, and obtain cosmic shear measurement with a signal-to-noise of 83, a factor of 2 higher than the Year 3 analysis. We model the uncertainties due to shear and redshift calibrations, and discard measurements on small angular scales to mitigate baryon feedback and other small-scale uncertainties. We consider two fiducial models to account for the intrinsic alignment (IA) of the galaxies. We conduct a blind analysis in the context of the $Λ$CDM model and find $S_8 \equiv σ_8(Ω_m/0.3)^{0.5}=0.798^{+0.014}_{-0.015}$ (marginalized mean with 68% CL) when using the non-linear alignment model (NLA) and $S_{8} = 0.783^{+0.019}_{-0.015}$ with the tidal alignment and tidal torque model (TATT), providing 1.8% and 2.5% uncertainty on $S_8$. Compared to constraints from the cosmic microwave background from Planck 2018, ACT DR6 and SPT-3G DR1, we find consistency in the full parameter space at 1.1$σ$ (1.7$σ$) and in $S_8$ at 2.0$σ$ (2.3$σ$) for NLA (TATT). The result using the NLA model is preferred according to the Bayesian evidence. We find that the model choice for IA and baryon feedback can impact the value of our $S_8$ constraint up to $1σ$. For our fiducial model choices, the resultant uncertainties in $S_8$ are primarily degraded by the removal of scales, as well as the marginalization over the IA parameters. We demonstrate that our result is internally consistent and robust to different choices in calibrating the data, owing to methodological improvements in shear and redshift measurement, laying the foundation for next-generation cosmic shear programs.

2602.10064 2026-02-11 cond-mat.mtrl-sci physics.comp-ph

PySlice: Routine Vibrational Electron Energy Loss Spectroscopy Prediction with Universal Interatomic Potentials

Harrison A. Walker, Thomas W. Pfeifer, Paul M. Zeiger, Jordan A. Hachtel, Sokrates T. Pantelides, Eric R. Hoglund

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Vibrational spectroscopy in the electron microscope can reveal phonon excitations with nanometer spatial resolution, yet routine prediction remains out of reach due to fragmented workflows requiring specialized expertise. Here we introduce PySlice, the first publicly available implementation of the Time Autocorrelation of Auxiliary Wavefunction (TACAW) method, providing an automated framework that produces momentum- and energy-resolved vibrational electron energy-loss spectra directly from atomic structures. By integrating universal machine learning interatomic potentials with TACAW, PySlice eliminates the bottleneck of per-system potential development. Users input atomic structures and obtain phonon dispersions, spectral diffraction patterns, and spectrum images through a unified workflow spanning molecular dynamics, GPU-accelerated electron scattering, and frequency-domain analysis. We outline the formulation behind the code, demonstrate its application to canonical systems in materials science, and discuss its use for advanced analysis and materials exploration. The modular Python architecture additionally supports conventional electron microscopy simulations, providing a general-purpose platform for imaging and diffraction calculations. PySlice makes vibrational spectroscopy prediction routine rather than specialized, enabling computational screening for experimental design, systematic exploration of phonon physics across materials families, and high-throughput generation of simulated data for training of future machine learning models.

2602.10061 2026-02-11 math.AP physics.ao-ph

Confinement results near point vortices on the rotating sphere

Martin Donati, Emeric Roulley

Comments 46 pages

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We study the Euler equation on the rotating sphere in the case where the absolute vorticity is initially sharply concentrated around several points. We follow the literature already concerning vorticity confinement for the planar Euler equations, and obtain similar results on the rotating sphere, with new challenges due to the geometry. More precisely, we show the improbability of collisions for point-vortices, logarithmic in time absolute vorticity confinement for general configurations, the optimality of this last result in general, and the existence of configurations with power-law long confinement. We take this opportunity to write a unified, self-contained, and improved version of all the proofs, previously scattered across multiple papers on the planar case, with detailed exposition for pedagogical clarity.

2602.10060 2026-02-11 cond-mat.dis-nn

Early warning signals for phase transitions in networks

A. V. Goltsev, S. N. Dorogovtsev

Comments 12 pages

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The percolation phase transition in complex network systems attracts much attention and has numerous applications in various research fields. Finite size effects smooth the transition and make it difficult to predict the critical point of appearance or disappearance of the giant connected component. For this end, we introduce the susceptibility of arbitrary random undirected and directed networks and show that a strong increase of the susceptibility is the early warning signal of approaching the transition point. Our method is based on the introduction of `observers', which are randomly chosen nodes monitoring the local connectivity of a network. To demonstrate efficiency of the method, we derive explicit equations determining the susceptibility and study its critical behavior near continuous and mixed-order phase transitions in uncorrelated random undirected and directed networks, networks with dependency links, and $k$-cores of networks. The universality of the critical behavior is supported by the phenomenological Landau theory of phase transitions.

2602.10059 2026-02-11 math.AP

Convergence to equilibrium for a class of coagulation-fragmentation equations without detailed balance

Apratim Bhattacharya, Sebastian Throm

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We prove convergence to equilibrium for a class of coagulation-fragmentation equations that do not satisfy a detailed balance condition. More precisely, we consider perturbations of constant rate kernels. Our result provides in particular explicit convergence rates. Uniqueness of the stationary states is proven as well for the considered class of kernels.

2602.10055 2026-02-11 math.ST stat.TH

The weak law of large numbers for the friendship paradox index

Mingao Yuan

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The friendship paradox index is a network summary statistic used to quantify the friendship paradox, which describes the tendency for an individual's friends to have more friends than the individual. In this paper, we utilize Markov's inequality to derive the weak law of large numbers for the friendship paradox index in a random geometric graph, a widely-used model for networks with spatial dependence and geometry. For uniform random geometric graph, where the nodes are uniformly distributed in a space, the friendship paradox index is asymptotically equal to $1/4$. On the contrary, in nonuniform random geometric graphs, the nonuniform node distribution leads to distinct limiting properties for the index. In the relatively sparse regime, the friendship paradox index is still asymptotically equal to $1/4$, the same as in the uniform case. In the intermediate sparse regime, however, the index converges in probability to $1/4$ plus a constant that is explicitly dependent on the node distribution. Finally, in the relatively dense case, the index diverges to infinity as the graph size increases. Our results highlight the sharp contrast between the uniform case and its nonuniform counterpart.

2602.10054 2026-02-11 cs.HC

AIDED: Augmenting Interior Design with Human Experience Data for Designer-AI Co-Design

Yang Chen Lin, Chen-Ying Chen, Kai-Hsin Hou, Hung-Yu Chen, Po-Chih Kuo

Comments 29 pages, 14 figures, Accepted to CHI 2026

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Interior design often struggles to capture the subtleties of client experience, leaving gaps between what clients feel and what designers can act upon. We present AIDED, a designer-AI co-design workflow that integrates multimodal client data into generative AI (GAI) design processes. In a within-subjects study with twelve professional designers, we compared four modalities: baseline briefs, gaze heatmaps, questionnaire visualizations, and AI-predicted overlays. Results show that questionnaire data were trusted, creativity-enhancing, and satisfying; gaze heatmaps increased cognitive load; and AI-predicted overlays improved GAI communication but required natural language mediation to establish trust. Interviews confirmed that an authenticity-interpretability trade-off is central to balancing client voices with professional control. Our contributions are: (1) a system that incorporates experiential client signals into GAI design workflows; (2) empirical evidence of how different modalities affect design outcomes; and (3) implications for future AI tools that support human-data interaction in creative practice.

2602.10051 2026-02-11 math.GT math.SG

Infinitely many Lefschetz pencils on ruled surfaces

Seraphina Eun Bi Lee, Carlos A. Serván

Comments 50 pages, 10 figures

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We show that any ruled surface $X$ with $χ(X) < 0$ admits infinitely many inequivalent Lefschetz pencils of fixed genus and number of base points. Our proof proceeds by building infinitely many inequivalent Lefschetz fibrations on a blow-up $X \# 4 \overline{\mathbb{CP}^2}$ of $X$ with constant fiber class, via a mechanism known as partial conjugation. Furthermore, there exists a symplectic form on $X$ compatible with all such pencils, and similarly for the fibrations in $X\#4\overline{\mathbb{CP}^2}$. This provides the first example of this phenomenon and makes progress on Problem 4.98 of the K3 list of problems in low-dimensional topology in the case of ruled surfaces.

2602.10050 2026-02-11 cs.DS

Maximizing Diversity in (near-)Median String Selection

Diptarka Chakraborty, Rudrayan Kundu, Nidhi Purohit, Aravinda Kanchana Ruwanpathirana

Comments Accepted for publication at CPM 2026

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Given a set of strings over a specified alphabet, identifying a median or consensus string that minimizes the total distance to all input strings is a fundamental data aggregation problem. When the Hamming distance is considered as the underlying metric, this problem has extensive applications, ranging from bioinformatics to pattern recognition. However, modern applications often require the generation of multiple (near-)optimal yet diverse median strings to enhance flexibility and robustness in decision-making. In this study, we address this need by focusing on two prominent diversity measures: sum dispersion and min dispersion. We first introduce an exact algorithm for the diameter variant of the problem, which identifies pairs of near-optimal medians that are maximally diverse. Subsequently, we propose a $(1-ε)$-approximation algorithm (for any $ε>0$) for sum dispersion, as well as a bi-criteria approximation algorithm for the more challenging min dispersion case, allowing the generation of multiple (more than two) diverse near-optimal Hamming medians. Our approach primarily leverages structural insights into the Hamming median space and also draws on techniques from error-correcting code construction to establish these results.

2602.10047 2026-02-11 math.AG math.CV math.DG math.DS

A lower bound for the Milnor number of vector fields

Maurício Corrêa, Gilcione Nonato Costa, Alejandra Salamanca Russi

Comments 21 pages

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We study holomorphic vector fields whose singular locus contains a local complete intersection smooth positive-dimensional component. We prove global and local formulas expressing the limiting Milnor/Poincare-Hopf contribution along such a component in terms of its embedded scheme structure, and we obtain sharp lower bounds for this contribution under holomorphic perturbations. We provide explicit families show optimality and illustrate how singularities may redistribute between a fixed neighborhood of the component and the part at infinity in projective compactifications.

2602.10046 2026-02-11 cs.SE

Artisan: Agentic Artifact Evaluation

Doehyun Baek, Michael Pradel

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Artifact evaluation has become standard practice in the software engineering community to ensure the reproducibility of research results. However, the current manual process is labor-intensive, and hence, done only as a one-time assessment for a subset of all papers. To support the artifact evaluation effort, we present Artisan, an automated LLM agent for reproducing research results given a paper and its artifact. The approach is enabled by two key contributions: First, we frame the reproduction problem as a code generation task where the goal is to generate a reproduction script that, when executed, reproduces the results reported in a paper. Unlike prior work on automatically reproducing research results in other domains, this formulation allows for running the script independently of the agent and for assessing the reproduction process at a fine-grained level. Second, we design automated judging mechanism that guides the agent toward the expected results without revealing them and that prevent trivial solutions, such as simply copying checked-in results. To evaluate Artisan, we introduce Artisan-Bench, the first benchmark assessing the ability to generate reproduction scripts and the first benchmark for automated artifact evaluation in software engineering. Artisan-Bench comprises 60 tasks derived from 23 software engineering papers, covering different research areas and programming languages. We validate all tasks in Artisan-Bench for reproducibility to ensure that the tasks are feasible. Our experiments show that Artisan is effective, producing 44/60 reproduction scripts and outperforming the best available baseline, a vanilla LLM agent (mini-swe-agent), by 3.14$\times$ in terms of reproduction scripts generated while taking $0.45 and 48 minutes, on average per task. Artisan also helped uncover 20 new errors in either the paper or artifact.

2602.10041 2026-02-11 physics.plasm-ph

Design of experiments characterising heat conduction in magnetised, weakly collisional plasma

T. A. Vincent, P. Ariyathilaka, L. Creaser, C. Danson, D. Lamb, J. Meinecke, C. A. J. Palmer, S. Pitt, H. Poole, C. Spindloe, P. Thomas, E. Tubman, L. Wilson, W. J. Garbett, G. Gregori, P. Tzeferacos, T. Hodge, A. F. A. Bott

Comments 34 pages, 17 figures, 2 tables

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Heat conduction in weakly collisional, magnetised plasma is challenging to model accurately due to multifaceted physics governing heat-carrying electrons, including microinstabilities that scatter electrons and modify heat transport. Capturing these effects requires multidimensional kinetic theory simulations, which are computationally expensive. Experimental constraints overcome this issue, resulting in improved understanding of thermal transport in systems such as the intra-cluster medium of galaxy clusters, and the hot-spot in inertial confinement fusion. In this paper, we present a new experimental platform that produces a weakly collisional high-\b{eta} plasma expected to be susceptible to the whistler heat-flux instability. This platform, to be fielded on the Orion laser, enables characterisation of whistler-regulated thermal conductivity. The platform design is assessed using radiation-magnetohydrodynamics simulations with the code FLASH. Simulations using three thermal conduction models predict conductivity suppression by over an order of magnitude relative to the Spitzer value at whistler saturation, demonstrating the efficacy of the platform.

2602.10039 2026-02-11 cs.CY

Budgeting Discretion: Theory and Evidence on Street-Level Decision-Making

Gaurab Pokharel, Sanmay Das, Patrick J. Fowler

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Street-level bureaucrats, such as caseworkers and border guards routinely face the dilemma of whether to follow rigid policy or exercise discretion based on professional judgement. However, frequent overrides threaten consistency and introduce bias, explaining why bureaucracies often ration discretion as a finite resource. While prior work models discretion as a static cost-benefit tradeoff, we lack a principled model of how discretion should be rationed over time under real operational constraints. We formalize discretion as a dynamic allocation problem in which an agent receives stochastic opportunities to improve upon a default policy and must spend a limited override budget K over a finite horizon T. We show that overrides follow a dynamic threshold rule: use discretion only when the opportunity exceeds a time and budget-dependent cutoff. Our main theoretical contribution identifies a behavioral invariance: for location-scale families of improvement distributions, the rate at which an optimal agent exercises discretion is independent of the scale of potential gains and depends only on the distribution's shape (e.g., tail heaviness). This result implies systematic differences in discretionary "policy personality." When gains are fat-tailed, optimal agents are patient, conserving discretion for outliers. When gains are thin-tailed, agents spend more routinely. We illustrate these implications using data from a homelessness services system. Discretionary overrides track operational constraints: they are higher at the start of the workweek, suppressed on weekends when intake is offline, and shift with short-run housing capacity. These results suggest that discretion can be both procedurally constrained and welfare-improving when treated as an explicitly budgeted resource, providing a foundation for auditing override patterns and designing decision-support systems.

2602.10038 2026-02-11 physics.optics cond-mat.mes-hall cond-mat.str-el

Nonreciprocal lensing and backscattering suppression via magneto-optical nonlocality

Dmitry Vagin, Maxim A. Gorlach

Comments 6 pages + 10 pages of Supplementary Materials

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We introduce a special kind of nonreciprocal electromagnetic response which gives rise to backscattering suppression in the bulk, a long-sought feature in topological photonics, as well as nonreciprocal lensing - an effect when the same structure focuses light incident from one direction and defocuses light propagating in the opposite way. We predict this response in spin spirals and in specially designed metamaterials, validating the key predictions.

2602.10036 2026-02-11 cs.FL

Automata on Graph Alphabets

Hugo Bazille, Uli Fahrenberg

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The theory of finite automata concerns itself with words in a free monoid together with concatenation and without further structure. There are, however, important applications which use alphabets which are structured in some sense. We introduce automata over a particular type of structured data, namely an alphabet which is given as a (finite or infinite) directed graph. This constrains concatenation: two strings may only be concatenated if the end vertex of the first is equal to the start vertex of the second. We develop the beginnings of an automata theory for languages on graph alphabets. We show that they admit a Kleene theorem, relating rational and regular languages, and a Myhill-Nerode theorem, stating that languages are regular iff they have finite prefix or, equivalently, suffix quotient. We present determinization and minimization algorithms, but we also exhibit that regular languages are not stable by complementation. Finally, we mention how these structures could be generalized to presimplicial alphabets, where languages are no more freely generated.

2602.10034 2026-02-11 cond-mat.mtrl-sci

Multiscale Modeling of Metal/Oxide/Metal Conductive Bridging Random Access Memory Cells: from Ab Initio to Finite Element Calculations

Jan Aeschlimann, Fabian Durch, Christoph Weilenmann, Alexandros Emboras, Mathieu Luisier, Juerg Leuthold

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We present a multiscale simulation framework to compute the current vs. voltage (I-V ) characteristics of metal/oxide/metal structures building the core of conductive bridging random access memory (CBRAM) cells and to shed light on their resistance switching properties. The approach relies on a finite element model whose input material parameters are extracted either from ab initio or from machine-learned empirical calculations. The applied techniques range from molecular dynamics and nudged elastic band to electronic and thermal quantum transport. Such an approach drastically reduces the number of fitting parameters needed and makes the resulting modeling environment more accurate than traditional ones. The developed computational framework is then applied to the investigation of an Ag/a-SiO2/Pt CBRAM, reproducing experimental data very well. Moreover, the relevance of Joule heating is assessed by considering various cell geometries. It is found that self-heating manifests itself in devices with thin conductive filaments with few-nanometer diameters and at current concentrations in the 10s-microampere range. With the proposed methodology it is now possible to explore the potential of not-yet fabricated memory cells and to reliably optimize their design.

2602.10030 2026-02-11 cs.CC

Optimal PRGs for Low-Degree Polynomials over Polynomial-Size Fields

Gil Cohen, Dean Doron, Noam Goldgraber

Comments arXiv admin note: text overlap with arXiv:2402.11915 by other authors

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Pseudorandom generators (PRGs) for low-degree polynomials are a central object in pseudorandomness, with applications to circuit lower bounds and derandomization. Viola's celebrated construction gives a PRG over the binary field, but with seed length exponential in the degree $d$. This exponential dependence can be avoided over sufficiently large fields. In particular, Dwivedi, Guo, and Volk constructed PRGs with optimal seed length over fields of size exponential in $d$. The latter builds on the framework of Derksen and Viola, who obtained optimal-seed constructions over fields of size polynomial in $d$, although growing with the number of variables $n$. In this work, we construct the first PRG with optimal seed length for degree-$d$ polynomials over fields of polynomial size, specifically $q \approx d^4$, assuming sufficiently large characteristic. Our construction follows the framework of prior work and reduces the required field size by replacing the hitting-set generator used in previous constructions with a new pseudorandom object. We also observe a threshold phenomenon in the field-size dependence. Specifically, we prove that constructing PRGs over fields of sublinear size, for example $q = d^{0.99}$ where $q$ is a power of two, would already yield PRGs for the binary field with comparable seed length via our reduction, provided that the construction imposes no restriction on the characteristic. While a breakdown of existing techniques has been noted before, we prove that this phenomenon is inherent to the problem itself, irrespective of the technique used.

2602.10028 2026-02-11 cs.IT math.IT

On the generalization of $g$-circulant MDS matrices

Atif Ahmad Khan, Shakir Ali, Bhupendra Singh

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英文摘要

A matrix $M$ over the finite field $ \mathbb{F}_q $ is called \emph{maximum distance separable} (MDS) if all of its square submatrices are non-singular. These MDS matrices are very important in cryptography and coding theory because they provide strong data protection and help spread information efficiently. In this paper, we introduce a new type of matrix called a \emph{consta-$g$-circulant matrix}, which extends the idea of $g$-circulant matrices. These matrices come from a linear transformation defined by the polynomial $ h(x) = x^m - λ+ \sum_{i=0}^{m-1} h_i x^i $ over $ \mathbb{F}_q $. We find the upper bound of such matrices exist and give conditions to check when they are invertible. This helps us know when they are MDS matrices. If the polynomial $ x^m - λ$ factors as $ x^m - λ= \prod_{i=1}^{t} f_i(x)^{e_i}, $ where each \( f_i(x) \) is irreducible, then the number of invertible consta-$g$-circulant matrices is $ N \cdot \prod_{i=1}^{t} \left( q^{°f_i} - 1 \right), $ where $r$ is the multiplicative order of $λ$, and \( N \) is the number of integers \( k \) such that $ 0 \leq k < \left\lfloor \frac{m - 1}{r} \right\rfloor + 1 \quad \text{and} \quad \gcd(1 + rk, m) = 1. $ This formula help us to reduce the number of cases to check whether such matrices is MDS. Moreover, we give complete characterization of $g$-circulant MDS matrices of order 3 and 4. Additionally, inspired by skew polynomial rings, we construct a new variant of $g$-circulant matrix. In the last, we provide some examples related to our findings.

2602.10027 2026-02-11 cs.DB

Optimal Bounds-Only Pruning for Spatial AkNN Joins

Dominik Winecki

详情
英文摘要

We propose a bounds-only pruning test for exact Euclidean AkNN joins on partitioned spatial datasets. Data warehouses commonly partition large tables and store row group statistics for them to accelerate searches and joins, rather than maintaining indexes. AkNN joins can benefit from such statistics by constructing bounds and localizing join evaluations to a few partitions before loading them to build spatial indexes. Existing pruning methods are overly conservative for bounds-only spatial data because they do not fully capture its directional semantics, thereby missing opportunities to skip unneeded partitions at the earliest stages of a join. We propose a three-bound proximity test to determine whether all points within a partition have a closer neighbor in one partition than in another, potentially occluded partition. We show that our algorithm is both optimal and efficient.

2602.10026 2026-02-11 stat.ME

Degrees-of-Freedom Approximations for Conditional-Mean Inference in Random-Lot Stability Analysis

Andrew T. Karl, Heath Rushing, Richard K. Burdick, Jeff Hofer

详情
英文摘要

Linear mixed models are widely used for pharmaceutical stability trending when sufficient lots are available. Expiry support is typically based on whether lot-specific conditional-mean confidence limits remain within specification through a proposed expiry. These limits depend on the denominator degrees-of-freedom (DDF) method used for $t$-based inference. We document an operationally important boundary-proximal phenomenon: when a fitted random-effect variance component is close to zero, Satterthwaite DDF for conditional-mean predictions can collapse, inflating $t$ critical values and producing unnecessarily wide and sometimes nonmonotone pointwise confidence limits on scheduled time grids. In contrast, containment DDF yields stable degrees of freedom and avoids sharp discontinuities as variance components approach the boundary. Using a worked example and simulation studies, we show that DDF choice can materially change pass/fail conclusions even when observed data comfortably meet specifications. Containment-based inference with the full random-effects model provides a single modeling framework that avoids the discontinuities introduced by data-dependent model reduction at arbitrary cutoffs. When containment is unavailable, a 10\% variance-contribution reduction workflow mitigates extreme Satterthwaite behavior by simplifying the random-effects structure only when fitted contributions at the proposed expiry are negligible. An AICc step-down is also evaluated but is best treated as a sensitivity analysis, as it can be liberal when the margin between the mean trend and the specification limit at the proposed expiry is small.

2602.10025 2026-02-11 eess.SP

RIS-Assisted Rank Enhancement With Commodity WiFi Transceivers: Real-World Experiments

Aymen Khaleel, Aydin Sezgin

Comments 5 pages, 3 figures, 2 tables, submitted for publication

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英文摘要

Reconfigurable intelligent surfaces (RISs) are a promising enabling technology for the sixth-generation ($6$G) of wireless communications. RISs, thanks to their intelligent design, can reshape the wireless channel to provide favorable propagation conditions for information transfer. In this work, we experimentally investigate the potential of RISs to enhance the effective rank of multiple-input multiple-output (MIMO) channels, thereby improving spatial multiplexing capabilities. In our experiment, commodity WiFi transceivers are used, representing a practical MIMO system. In this context, we propose a passive beam-focusing technique to manipulate the propagation channel between each transmit-receive antenna pair and achieve a favorable propagation condition for rank improvement. The proposed algorithm is tested in two different channel scenarios: low and medium ranks. Experimental results show that, when the channel is rank-deficient, the RIS can significantly increase the rank by $112\%$ from its default value without the RIS, providing a rank increment of $1.5$. When the rank has a medium value, a maximum of $61\%$ enhancement can be achieved, corresponding to a rank increment of $1$. These results provide the first experimental evidence of RIS-driven rank manipulation with off-the-shelf WiFi hardware, offering practical insights into RIS deployment for spatial multiplexing gains.

2602.10020 2026-02-11 cs.IT math.IT

METTLE: Efficient Streaming Erasure Code with Peeling Decodability

Qianru Yu, Tianji Yang, Jingfan Meng, Jun Xu

Comments 31 pages

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英文摘要

In this work, we solve a long-standing open problem in coding theory with broad applications in networking and systems: designing an erasure code that simultaneously satisfies three requirements: (1) high coding efficiency, (2) low coding complexity, and (3) being a streaming code (defined as one with low decoding latency). We propose METTLE (Multi-Edge Type with Touch-less Leading Edge), the first erasure code to meet all three requirements. Compared to "streaming RaptorQ" (RaptorQ configured with a small source block size to ensure a low decoding latency), METTLE is only slightly worse in coding efficiency, but 47.7 to 84.6 times faster to decode.

2602.10018 2026-02-11 stat.ME math.ST stat.ML stat.TH

Online Selective Conformal Prediction with Asymmetric Rules: A Permutation Test Approach

Mingyi Zheng, Ying Jin

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英文摘要

Selective conformal prediction aims to construct prediction sets with valid coverage for a test unit conditional on it being selected by a data-driven mechanism. While existing methods in the offline setting handle any selection mechanism that is permutation invariant to the labeled data, their extension to the online setting -- where data arrives sequentially and later decisions depend on earlier ones -- is challenged by the fact that the selection mechanism is naturally asymmetric. As such, existing methods only address a limited collection of selection mechanisms. In this paper, we propose PErmutation-based Mondrian Conformal Inference (PEMI), a general permutation-based framework for selective conformal prediction with arbitrary asymmetric selection rules. Motivated by full and Mondrian conformal prediction, PEMI identifies all permutations of the observed data (or a Monte-Carlo subset thereof) that lead to the same selection event, and calibrates a prediction set using conformity scores over this selection-preserving reference set. Under standard exchangeability conditions, our prediction sets achieve finite-sample exact selection-conditional coverage for any asymmetric selection mechanism and any prediction model. PEMI naturally incorporates additional offline labeled data, extends to selection mechanisms with multiple test samples, and achieves FCR control with fine-grained selection taxonomies. We further work out several efficient instantiations for commonly-used online selection rules, including covariate-based rules, conformal p/e-values-based procedures, and selection based on earlier outcomes. Finally, we demonstrate the efficacy of our methods across various selection rules on a real drug discovery dataset and investigate their performance via simulations.

2602.10012 2026-02-11 stat.ME

Doubly Robust Estimation of Desirability of Outcome Ranking (DOOR) Probability with Application to MDRO Studies

Shiyu Shu, Toshimitsu Hamasaki, Scott Evans, Lauren Komarow, David van Duin, Guoqing Diao

详情
英文摘要

In observational studies, adjusting for confounders is required if a treatment comparison is planned. A crude comparison of the primary endpoint without covariate adjustment will suffer from biases, and the addition of regression models could improve precision by incorporating imbalanced covariates and thus help make correct inference. Desirability of outcome ranking (DOOR) is a patient-centric benefit-risk evaluation methodology designed for randomized clinical trials. Still, robust covariate adjustment methods could further expand the compatibility of this method in observational studies. In DOOR analysis, each participant's outcome is ranked based on pre-specified clinical criteria, where the most desirable rank represents a good outcome with no side effects and the least desirable rank is the worst possible clinical outcome. We develop a causal framework for estimating the population-level DOOR probability, via the inverse probability of treatment weighting method, G-Computation method, and a Doubly Robust method that combines both. The performance of the proposed methodologies is examined through simulations. We also perform a causal analysis of the Multi-Drug Resistant Organism (MDRO) network within the Antibacterial Resistant Leadership Group (ARLG), comparing the benefit:risk between Mono-drug therapy and Combination-drug therapy.

2602.10011 2026-02-11 physics.med-ph q-bio.OT

Towards a topological view of blood pressure regulation

Arturo Tozzi

Comments 9 pages, one figure

详情
英文摘要

Blood pressure regulation is commonly addressed in terms of local mechanisms such as vascular resistance, compliance and neurohumoral control. However, the human vasculature encompasses multiple quasi-closed flow loops under both physiological and pathological conditions. To test whether these loops could influence pressure dynamics beyond local control, we address the role of vascular topology in blood pressure regulation. Using one dimensional flow simulation models, we compared pressure dynamics in open vascular segments and closed vascular loops. We found that in open segments pressure fades away and remains spatially localized, whereas in closed loops pressure can keep circulating around the loop even if resistance in one spot is modified. Since parallel pathways within loops are dynamically coupled rather than independent, pressure changes in one place can affect the entire closed loop, allowing system level pressure patterns to emerge. Also, we assessed the temporal evolution of pressure fluctuations within closed vascular loops in normotensive and hypertensive parameter regimes, before and after loop breaking intervention. This topological approach helps clarifying why drugs or local interventions may fail to lower blood pressure in looped vascular architectures, providing a theoretical interpretation of some forms of resistant hypertension. Because disrupting a loop restores pressure relaxation, it may also help explain the disproportionate pressure changes observed after topology altering events like thrombosis, vascular surgery or embolization of arteriovenous malformations and shunts. Therefore, vascular topology can influence cardiovascular physiology by coupling local pressure flow relations to global constraints on blood pressure regulation, with physiological, pathological and clinical implications.