TY - JOUR AB - Writing concurrent code that is both correct and efficient is notoriously difficult. Thus, programmers often prefer to use synchronization abstractions, which render code simpler and easier to reason about. Despite a wealth of work on this topic, there is still a gap between the rich semantics provided by synchronization abstractions in modern programming languages—specifically, fair FIFO ordering of synchronization requests and support for abortable operations—and frameworks for implementing it correctly and efficiently. Supporting such semantics is critical given the rising popularity of constructs for asynchronous programming, such as coroutines, which abort frequently and are cheaper to suspend and resume compared to native threads. This paper introduces a new framework called CancellableQueueSynchronizer (CQS), which enables simple yet efficient implementations of a wide range of fair and abortable synchronization primitives: mutexes, semaphores, barriers, count-down latches, and blocking pools. Our main contribution is algorithmic, as implementing both fairness and abortability efficiently at this level of generality is non-trivial. Importantly, all our algorithms, including the CQS framework and the primitives built on top of it, come with formal proofs in the Iris framework for Coq for many of their properties. These proofs are modular, so it is easy to show correctness for new primitives implemented on top of CQS. From a practical perspective, implementation of CQS for native threads on the JVM improves throughput by up to two orders of magnitude over Java’s AbstractQueuedSynchronizer, the only practical abstraction offering similar semantics. Further, we successfully integrated CQS as a core component of the popular Kotlin Coroutines library, validating the framework’s practical impact and expressiveness in a real-world environment. In sum, CancellableQueueSynchronizer is the first framework to combine expressiveness with formal guarantees and solid practical performance. Our approach should be extensible to other languages and families of synchronization primitives. AU - Koval, Nikita AU - Khalanskiy, Dmitry AU - Alistarh, Dan-Adrian ID - 13179 JF - Proceedings of the ACM on Programming Languages TI - CQS: A formally-verified framework for fair and abortable synchronization VL - 7 ER - TY - JOUR AB - We study the density of everywhere locally soluble diagonal quadric surfaces, parameterised by rational points that lie on a split quadric surface AU - Browning, Timothy D AU - Lyczak, Julian AU - Sarapin, Roman ID - 13180 IS - 2 JF - Involve SN - 1944-4176 TI - Local solubility for a family of quadrics over a split quadric surface VL - 16 ER - TY - GEN AU - Elefante, Stefano AU - Stadlbauer, Stephan AU - Alexander, Michael F AU - Schlögl, Alois ID - 13162 T2 - ASHPC23 - Austrian-Slovenian HPC Meeting 2023 TI - Cryo-EM software packages: A sys-admins point of view ER - TY - GEN AU - Schlögl, Alois AU - Elefante, Stefano AU - Hodirnau, Victor-Valentin ID - 13161 T2 - ASHPC23 - Austrian-Slovenian HPC Meeting 2023 TI - Running Windows-applications on a Linux HPC cluster using WINE ER - TY - JOUR AB - A rotating organic cation and a dynamically disordered soft inorganic cage are the hallmark features of organic-inorganic lead-halide perovskites. Understanding the interplay between these two subsystems is a challenging problem, but it is this coupling that is widely conjectured to be responsible for the unique behavior of photocarriers in these materials. In this work, we use the fact that the polarizability of the organic cation strongly depends on the ambient electrostatic environment to put the molecule forward as a sensitive probe of the local crystal fields inside the lattice cell. We measure the average polarizability of the C/N–H bond stretching mode by means of infrared spectroscopy, which allows us to deduce the character of the motion of the cation molecule, find the magnitude of the local crystal field, and place an estimate on the strength of the hydrogen bond between the hydrogen and halide atoms. Our results pave the way for understanding electric fields in lead-halide perovskites using infrared bond spectroscopy. AU - Wei, Yujing AU - Volosniev, Artem AU - Lorenc, Dusan AU - Zhumekenov, Ayan A. AU - Bakr, Osman M. AU - Lemeshko, Mikhail AU - Alpichshev, Zhanybek ID - 13251 IS - 27 JF - The Journal of Physical Chemistry Letters KW - General Materials Science KW - Physical and Theoretical Chemistry TI - Bond polarizability as a probe of local crystal fields in hybrid lead-halide perovskites VL - 14 ER -