Tootfinder

Reconstruction Bias in Timepix4 Subpixel Centroiding for Electron Imaging
Nina Dimova, Richard Plackett, Daniela Bortoletto
https://arxiv.org/abs/2608.21072 https://arxiv.org/pdf/2608.21072 https://arxiv.org/html/2608.21072
arXiv:2608.21072v1 Announce Type: new
Abstract: Subpixel centroiding is widely used to improve the spatial resolution of hybrid pixel detectors for electron imaging by estimating the true interaction position within an entry pixel. Existing centroiding strategies are typically optimised using localisation accuracy. However, observations show that improved localisation does not necessarily translate into improved modulation transfer function (MTF) or reliable virtual-pixel rebinning. This work proposes a unified interpretation of these observations based on the ambiguity of the centroid reconstruction problem. We show that observable-based centroid estimators solve an intrinsically non-unique inverse problem using deterministic reconstruction rules, which can introduce entry-phase-dependent reconstruction bias that governs the spatial distribution of reconstructed subpixel coordinates. This framework explains why localisation accuracy alone is insufficient to predict imaging performance and identifies approximate intra-pixel translational symmetry as a prerequisite for faithful virtual-pixel imaging. The proposed interpretation is evaluated using simulated 200 keV and 300 keV electron data together with measured 200 keV data acquired with a Timepix4 detector. Comparisons of charge-weighted, timing-based, and morphology-dependent centroiding strategies demonstrate that estimators with similar localisation performance can exhibit markedly different MTFs and rebinned flat-field behaviour. The results suggest that future centroid optimisation should consider subpixel phase bias and rebinnability alongside localisation accuracy.
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https://www.wsj.com/tech/apple-price…

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"These group exercises and private corrections resemble tactics used in Synanon, a notorious and controversial drug treatment program seen as one of the first versions of a therapeutic community model. The Other Side Academy leaders don’t claim a tie to that program. But Delancey Street Foundation — where several ear…

A Unified Framework for Uniform-Price Resource Allocation Mechanisms
Ioannis Caragiannis, Dimitris Fotakis, Stratis Skoulakis
https://arxiv.org/abs/2606.06151 https://arxiv.org/pdf/2606.06151 https://arxiv.org/html/2606.06151
arXiv:2606.06151v1 Announce Type: new
Abstract: Mechanisms for allocating a divisible resource among strategic agents have been widely studied. The prominent paradigm is the proportional (Kelly) mechanism, which elicits a scalar bid per agent, allocates the resource proportionally, and charges payments equal to the bids. Follow-up mechanisms improve social welfare, but sacrifice simplicity by introducing complex allocation rules or unintuitive payments.
We introduce a unified framework for designing simple resource allocation mechanisms with proportional-style allocations and uniform pricing. Our framework yields a family of mechanisms that interpolate between the Kelly mechanism and the first-price auction. These mechanisms strictly improve upon Kelly's efficiency guarantees, even achieving full efficiency in equilibrium, while also providing revenue guarantees relative to the VCG mechanism.
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A Unified Framework for Uniform-Price Resource Allocation Mechanisms
Ioannis Caragiannis, Dimitris Fotakis, Stratis Skoulakis
https://arxiv.org/abs/2606.06151 https://