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Navigators learn a local graph, not a global map
No full textIt is still an unresolved issue how humans represent navigable space and use this information to relate distant locations, as when shortcuting or pointing. In the present study we compare two competing theoretical approaches to the structure of this spatial knowledge. We contrast the metric embedding of spatial information in a global reference frame (i.e., a Euclidean mental map) with models that assume only local place-to-place information (i.e., a labeled graph), which can be used to estimate shortcuts and pointing direction when needed. Two groups of participants learned a multi-corridor virtual maze by walking around a zig-zag loop that connected seven objects placed on a circle. One group experienced a possible Euclidean maze, and the other group an impossible, non-Euclidean, ‘broken’ version of the maze. In the impossible environment, after walking one lap the participant was covertly teleported to the starting place again, despite having walked to a different Euclidean location. Thus, the local place-to-place metrics were globally inconsistent. During the test phase, participants pointed to targets in a clockwise or counterclockwise sequence around the circle from their current location. Whereas the possible maze group was fairly accurate, the estimates of the impossible maze group were systematically biased by the test sequence, as predicted by local place-to-place metrics. Despite being queried about the same target, participants pointed in significantly different directions, violating the metric postulates. The results suggest that human knowledge of navigable space is not a globally consistent Euclidean map, but can be characterized as a labeled graph
More Images, More Problems? A Controlled Analysis of VLM Failure Modes
No full textLarge Vision Language Models (LVLMs) have demonstrated remarkable capabilities, yet their proficiency in understanding and reasoning over multiple images remains largely unexplored. While existing benchmarks have initiated the evaluation of multi-image models, a comprehensive analysis of their core weaknesses and their causes is still lacking. In this work, we introduce MIMIC (Multi-Image Model Insights and Challenges), a new benchmark designed to rigorously evaluate the multi-image capabilities of LVLMs. Using MIMIC, we conduct a series of diagnostic experiments that reveal pervasive issues: LVLMs often fail to aggregate information across images and struggle to track or attend to multiple concepts simultaneously. To address these failures, we propose two novel complementary remedies. On the data side, we present a procedural data-generation strategy that composes single-image annotations into rich, targeted multi-image training examples. On the optimization side, we analyze layer-wise attention patterns and derive an attention-masking scheme tailored for multi-image inputs. Experiments substantially improved cross-image aggregation, while also enhancing performance on existing multi-image benchmarks, outperforming prior state of the art across tasks. Data and code will be made available at https://github.com/anurag-198/MIMIC
Theta operators on Hodge type Shimura varieties
No full textWe construct a new family of mod weight shifting differential operators on Hodge type Shimura varieties at hyperspecial level. First we construct basic theta operators, labelled by positive roots, that generalize Katz's theta operator for modular forms. Secondly we construct theta linkage maps, these are operators between automorphic vector bundles with linked weights, which can be thought of as generalizations of the classical theta cycle of Tate--Jochnowitz. In particular, there exist such maps within the -restricted region, whose weight shifts are directly related to the conjectures of Herzig on the weight part of Serre's conjecture. We explain the relation between the two operators, and we prove some properties about them, e.g., the injectivity of some of them in a generic locus of the -restricted region. As an application, we produce an example of a generic entailment of Serre weights for the groups and , by combining the method of arxiv:2410.09602 with our stronger results about theta operators
The arrangement of anisotropic spin couplings can optimize sensitivity of the cryptochrome radical pair to the direction of geomagnetic field
No full textSensing of the geomagnetic field direction by many living organisms is commonly thought to involve radical pairs, such as those formed photochemically between the flavin and tryptophan radicals in the cryptochrome proteins. Previous theoretical studies have shown that strongly axial hyperfine couplings in the cryptochrome radicals greatly enhance the formation of a signaling state of the protein when the magnetic field is directed perpendicular to the hyperfine axis of either of the radicals. However, further analysis led to the conclusion that sharpness of detecting those magnetic directions is strongly suppressed by the inter-radical electron spin coupling. Here, we perform theoretical simulations of the compass function for a set of arrangements of the intra- and inter-radical spin couplings in the idealized cryptochrome radical pair, and find certain arrangements that preserve the sharpness in detecting the direction of the geomagnetic field. One particular arrangement, with the hyperfine axes of the radicals orthogonal to the symmetry axis of inter-radical coupling, provides even sharper field-direction sensitivity than that contributed solely by the anisotropy of the hyperfine coupling
When is Archaeology?: A flotation machine, an art exhibition and the (un)sievable realm of possibilities
No full textWhen a flotation machine, an object routinely employed at archaeological sites, was featured prominently in an art exhibition, its significance did not simply change. As well as interrupting the machine’s meaning (function), the act and event also made possible the emergence of new forms of attention, and of different means of engagement with the object. This paper explores the collaboration between archaeology and art where this occurred, the exhibition Geography of Looking in the Ar/Ge Kunst art space in the city of Bolzano in northeast Italy. The introduction of a flotation machine into the art space initiated a dialogue about the perception, interpretation and disciplinary boundaries of archaeology. Entangled in artistic discursive practice and curated as such, the flotation machine unexpectedly became more “archaeological”. The implications of this collaboration on our understanding and framing of archaeological practice elicited a new question: when is archaeology? This question foregrounds the potential of archaeology to become more democratic, inclusive and responsive, and proposes a more collective and boundary-crossing looking. The paper contributes to the growing discourse on contemporary archaeology and art, inviting further collaborations and co-creations. What role is there for archaeology approaching the contemporary, and is there a prospect for a deep and enduring looking into an alternative, otherwise world building
Two-body currents at finite momentum transfer and applications to M1 transitions
No full textWe explore the impact of two-body currents (2BCs) at finite momentum transfer with a focus on magnetic- dipole properties in 48Ca and 48Ti. To this end, we derive a multipole decomposition of 2BCs to fully include the momentum-transfer dependence in ab initio calculations. As application, we investigate the effects of 2BCs on the strong M1 transition at 10.23 MeV in 48Ca using the valence-space in-medium similarity renormalization group (VS-IMSRG) with a set of nonimplausible interactions as well as the 1.8/2.0 (EM) interaction. Experiments, such as (e, e′) and (γ , n), disagree on the magnetic-dipole strength B(M1) for this transition. Our VS-IMSRG results favor larger B(M1) values similar to recent coupled-cluster calculations. However, for this transition there are larger cancellations between the leading pion-in-flight and seagull 2BCs, so that future calculations including higher-order 2BCs are important. For validation of our results, we investigate additional observables in 48Ca as well as M1 transitions in 48Ti. For these, our results agree with experiment. Finally, our results show that for medium-mass nuclei 2BC contributions to M1 and Gamow-Teller transitions are, as expected, very different. Therefore, using similar quenching factors for both in phenomenological calculations is not supported from first principles
Eemian climate seasonality reconstructed from intra-tooth oxygen, carbon, and nitrogen stable isotopes in equid enamel from Neumark-Nord 2, Germany
No full textReconstructing the climate of central Europe during the Eemian serves a dual purpose. First, the Eemian represents the most recent pre-Holocene period of widespread climate warming, and its vegetation structure offers a potential natural baseline for temperate European vegetation, as it was unaffected by large-scale anthropogenic alterations. Second, because Neanderthals lived in Europe during this period, understanding the climate provides insights into their environmental adaptations.Here we examined seasonal climate variation at a sub-annual scale during the early Eemian (ca. 121 ± 5 ka) by analyzing oxygen isotopes (δ18OCO3) in tooth enamel of 14 serially sampled equid third molars from the Neanderthal occupation site of Neumark-Nord 2 (NN2), Germany. These specimens were retrieved from find level NN2/2B, which spans less than 500 years. Stable carbon (δ13CCO3) and mineral-bound nitrogen isotopes (δ15Nmb) were measured in the same enamel aliquots to assess seasonal influences on diet.Intra-tooth δ18OCO3 values show clear sinusoidal seasonal patterns, indicating mean annual temperatures of 11 ± 1 °C, which are closely aligned with previously published Eemian estimates and slightly higher than present-day values. However, modeled water δ18O suggest stronger seasonal contrasts than today, with summers ∼5 °C warmer and similar winter conditions. δ13CCO3 values indicate a semi-open habitat and more annual precipitation than today. Notably, δ13CCO3 and δ15Nmb values show no seasonal variation, implying stable year-round equid diets and consistent plant availability despite pronounced climate seasonality
