Characterization of optical systems for the ALPS II experiment

ALPS II is a light shining through a wall style experiment that will use the principle of resonant enhancement to boost the conversion and reconversion probabilities of photons to relativistic WISPs. This will require the use of long baseline low-loss optical cavities. Very high power build up factors in the cavities must be achieved in order to reach the design sensitivity of ALPS II. This necessitates a number of different sophisticated optical and control systems to maintain the resonance and ensure maximal coupling between the laser and the cavity. In this paper we report on the results of the characterization of these optical systems with a 20 m cavity and discuss the results in the context of ALPS II

The Working Sovereign: A conversation with Axel Honneth

In the summer of 2021, Axel Honneth was invited by the Centre for Social Critique Berlin to give the Walter Benjamin Lectures. The lectures have now been published in German under the title Der arbeitende Souverän (The Working Sovereign). In a conversation with the directors of the Centre for Social Critique, Rahel Jaeggi and Robin Celikates, Axel Honneth explains why he believes a political theory of labor is necessary, how the world of work has changed, and what opportunities and risks this entails for democratization processes.Peer Reviewe

The Working Sovereign: A conversation with Axel Honneth

In the summer of 2021, Axel Honneth was invited by the Centre for Social Critique Berlin to give the Walter Benjamin Lectures. The lectures have now been published in German under the title Der arbeitende Souverän (The Working Sovereign). In a conversation with the directors of the Centre for Social Critique, Rahel Jaeggi and Robin Celikates, Axel Honneth explains why he believes a political theory of labor is necessary, how the world of work has changed, and what opportunities and risks this entails for democratization processes

Adversarial Diffusion Distillation

We introduce Adversarial Diffusion Distillation (ADD), a novel training approach that efficiently samples large-scale foundational image diffusion models in just 1-4 steps while maintaining high image quality. We use score distillation to leverage large-scale off-the-shelf image diffusion models as a teacher signal in combination with an adversarial loss to ensure high image fidelity even in the low-step regime of one or two sampling steps. Our analyses show that our model clearly outperforms existing few-step methods (GANs, Latent Consistency Models) in a single step and reaches the performance of state-of-the-art diffusion models (SDXL) in only four steps. ADD is the first method to unlock single-step, real-time image synthesis with foundation models. Code and weights available under https://github.com/Stability-AI/generative-models and https://huggingface.co/stabilityai/

Bound states and local topological phase diagram of classical impurity spins coupled to a Chern insulator

The existence of bound states induced by local impurities coupled to an insulating host depends decisively on the global topological properties of the host's electronic structure. In this context, we consider magnetic impurities modelled as classical unit-length spins that are exchange-coupled to the spinful Haldane model on the honeycomb lattice. We investigate the spectral flow of bound states with the coupling strength $J$ in both the topologically trivial and Chern-insulating phases. In addition to conventional $k$-space topology, an additional, spatially local topological feature is available, based on the space of impurity-spin configurations forming, in case of $R$ impurities, an $R$-fold direct product of two-dimensional spheres. Global $k$-space and local $S$-space topology are represented by different topological invariants, the first ($k$-space) Chern number and the $R$-th ($S$-space) spin-Chern number. We demonstrate that there is a local $S$-space topological transition as a function of $J$ associated with a change in the spin Chern number and work out the implications of this for the $J$-dependent local electronic structure close to the impurities and, in particular, for in-gap bound states. The critical exchange couplings' dependence on the parameters of the Haldane model, and thus on the $k$-space topological state, is obtained numerically to construct local topological phase diagrams for systems with $R=1$ and $R=2$ impurity spins.Comment: 16 pages, 9 figure

Multiple conserved regulatory domains promote Fezf2 expression in the developing cerebral cortex.

BackgroundThe genetic programs required for development of the cerebral cortex are under intense investigation. However, non-coding DNA elements that control the expression of developmentally important genes remain poorly defined. Here we investigate the regulation of Fezf2, a transcription factor that is necessary for the generation of deep-layer cortical projection neurons.ResultsUsing a combination of chromatin immunoprecipitation followed by high throughput sequencing (ChIP-seq) we mapped the binding of four deep-layer-enriched transcription factors previously shown to be important for cortical development. Building upon this we characterized the activity of three regulatory regions around the Fezf2 locus at multiple stages throughout corticogenesis. We identified a promoter that was sufficient for expression in the cerebral cortex, and enhancers that drove reporter gene expression in distinct forebrain domains, including progenitor cells and cortical projection neurons.ConclusionsThese results provide insight into the regulatory logic controlling Fezf2 expression and further the understanding of how multiple non-coding regulatory domains can collaborate to control gene expression in vivo

Microstructure and mechanical properties of stable austenitic steel after thermomechanical treatment

The features of microstructure and mechanical properties of stable austenitic steel after thermomechanical treatment consist of low-temperature deformation, warm deformation and subsequent annealing have been investigated. It is shown that under these conditions in the steel direct (γ → α')- and inverse (α' → γ)-martensitic transformations are realized. As a result of the thermomechanical treatment submicrocrystalline structural states with a high density of micro- and nanotwins and localized deformation bands are formed. The yield strength of these structural states more than 3 times increases by the original value

A Fully-Coupled Electro-Mechanical Whole-Heart Computational Model: Influence of Cardiac Contraction on the ECG

The ECG is one of the most commonly used non-invasive tools to gain insights into the electrical functioning of the heart. It has been crucial as a foundation in the creation and validation of in silico models describing the underlying electrophysiological processes. However, so far, the contraction of the heart and its influences on the ECG have mainly been overlooked in in silico models. As the heart contracts and moves, so do the electrical sources within the heart responsible for the signal on the body surface, thus potentially altering the ECG. To illuminate these aspects, we developed a human 4-chamber electro-mechanically coupled whole heart in silico model and embedded it within a torso model. Our model faithfully reproduces measured 12-lead ECG traces, circulatory characteristics, as well as physiological ventricular rotation and atrioventricular valve plane displacement. We compare our dynamic model to three non-deforming ones in terms of standard clinically used ECG leads (Einthoven and Wilson) and body surface potential maps (BSPM). The non-deforming models consider the heart at its ventricular end-diastatic, end-diastolic and end-systolic states. The standard leads show negligible differences during P-Wave and QRS-Complex, yet during T-Wave the leads closest to the heart show prominent differences in amplitude. When looking at the BSPM, there are no notable differences during the P-Wave, but effects of cardiac motion can be observed already during the QRS-Complex, increasing further during the T-Wave. We conclude that for the modeling of activation (P-Wave/QRS-Complex), the associated effort of simulating a complete electro-mechanical approach is not worth the computational cost. But when looking at ventricular repolarization (T-Wave) in standard leads as well as BSPM, there are areas where the signal can be influenced by cardiac motion of the heart to an extent that should not be ignored