TY - CONF AB - We present the first deterministic wait-free long-lived snapshot algorithm, using only read and write operations, that guarantees polylogarithmic amortized step complexity in all executions. This is the first non-blocking snapshot algorithm, using reads and writes only, that has sub-linear amortized step complexity in executions of arbitrary length. The key to our construction is a novel implementation of a 2-component max array object which may be of independent interest. AU - Baig, Mirza Ahad AU - Hendler, Danny AU - Milani, Alessia AU - Travers, Corentin ID - 8382 SN - 9781450375825 T2 - Proceedings of the 39th Symposium on Principles of Distributed Computing TI - Long-lived snapshots with polylogarithmic amortized step complexity ER - TY - JOUR AB - In the superconducting regime of FeTe(1−x)Sex, there exist two types of vortices which are distinguished by the presence or absence of zero-energy states in their core. To understand their origin, we examine the interplay of Zeeman coupling and superconducting pairings in three-dimensional metals with band inversion. Weak Zeeman fields are found to suppress intraorbital spin-singlet pairing, known to localize the states at the ends of the vortices on the surface. On the other hand, an orbital-triplet pairing is shown to be stable against Zeeman interactions, but leads to delocalized zero-energy Majorana modes which extend through the vortex. In contrast, the finite-energy vortex modes remain localized at the vortex ends even when the pairing is of orbital-triplet form. Phenomenologically, this manifests as an observed disappearance of zero-bias peaks within the cores of topological vortices upon an increase of the applied magnetic field. The presence of magnetic impurities in FeTe(1−x)Sex, which are attracted to the vortices, would lead to such Zeeman-induced delocalization of Majorana modes in a fraction of vortices that capture a large enough number of magnetic impurities. Our results provide an explanation for the dichotomy between topological and nontopological vortices recently observed in FeTe(1−x)Sex. AU - Ghazaryan, Areg AU - Lopes, P. L.S. AU - Hosur, Pavan AU - Gilbert, Matthew J. AU - Ghaemi, Pouyan ID - 7428 IS - 2 JF - Physical Review B SN - 24699950 TI - Effect of Zeeman coupling on the Majorana vortex modes in iron-based topological superconductors VL - 101 ER - TY - JOUR AB - We demonstrate that releasing atoms into free space from an optical lattice does not deteriorate cavity-generated spin squeezing for metrological purposes. In this work, an ensemble of 500000 spin-squeezed atoms in a high-finesse optical cavity with near-uniform atom-cavity coupling is prepared, released into free space, recaptured in the cavity, and probed. Up to ∼10 dB of metrologically relevant squeezing is retrieved for 700μs free-fall times, and decaying levels of squeezing are realized for up to 3 ms free-fall times. The degradation of squeezing results from loss of atom-cavity coupling homogeneity between the initial squeezed state generation and final collective state readout. A theoretical model is developed to quantify this degradation and this model is experimentally validated. AU - Wu, Yunfan AU - Krishnakumar, Rajiv AU - Martínez-Rincón, Julián AU - Malia, Benjamin K. AU - Hosten, Onur AU - Kasevich, Mark A. ID - 8319 IS - 1 JF - Physical Review A SN - 24699926 TI - Retrieval of cavity-generated atomic spin squeezing after free-space release VL - 102 ER - TY - JOUR AB - Markov decision processes (MDPs) are the defacto framework for sequential decision making in the presence of stochastic uncertainty. A classical optimization criterion for MDPs is to maximize the expected discounted-sum payoff, which ignores low probability catastrophic events with highly negative impact on the system. On the other hand, risk-averse policies require the probability of undesirable events to be below a given threshold, but they do not account for optimization of the expected payoff. We consider MDPs with discounted-sum payoff with failure states which represent catastrophic outcomes. The objective of risk-constrained planning is to maximize the expected discounted-sum payoff among risk-averse policies that ensure the probability to encounter a failure state is below a desired threshold. Our main contribution is an efficient risk-constrained planning algorithm that combines UCT-like search with a predictor learned through interaction with the MDP (in the style of AlphaZero) and with a risk-constrained action selection via linear programming. We demonstrate the effectiveness of our approach with experiments on classical MDPs from the literature, including benchmarks with an order of 106 states. AU - Brázdil, Tomáš AU - Chatterjee, Krishnendu AU - Novotný, Petr AU - Vahala, Jiří ID - 15055 IS - 06 JF - Proceedings of the 34th AAAI Conference on Artificial Intelligence KW - General Medicine SN - 2374-3468 TI - Reinforcement learning of risk-constrained policies in Markov decision processes VL - 34 ER - TY - JOUR AB - Vaccinia virus–related kinase (VRK) is an evolutionarily conserved nuclear protein kinase. VRK-1, the single Caenorhabditis elegans VRK ortholog, functions in cell division and germline proliferation. However, the role of VRK-1 in postmitotic cells and adult life span remains unknown. Here, we show that VRK-1 increases organismal longevity by activating the cellular energy sensor, AMP-activated protein kinase (AMPK), via direct phosphorylation. We found that overexpression of vrk-1 in the soma of adult C. elegans increased life span and, conversely, inhibition of vrk-1 decreased life span. In addition, vrk-1 was required for longevity conferred by mutations that inhibit C. elegans mitochondrial respiration, which requires AMPK. VRK-1 directly phosphorylated and up-regulated AMPK in both C. elegans and cultured human cells. Thus, our data show that the somatic nuclear kinase, VRK-1, promotes longevity through AMPK activation, and this function appears to be conserved between C. elegans and humans. AU - Park, Sangsoon AU - Artan, Murat AU - Han, Seung Hyun AU - Park, Hae-Eun H. AU - Jung, Yoonji AU - Hwang, Ara B. AU - Shin, Won Sik AU - Kim, Kyong-Tai AU - Lee, Seung-Jae V. ID - 15057 IS - 27 JF - Science Advances TI - VRK-1 extends life span by activation of AMPK via phosphorylation VL - 6 ER -