TY - JOUR AB - The electrolyte is one of the greatest challenges facing the development of the non‐aqueous Li–O2 battery. Although ether‐based electrolytes do from Li2O2 on the first discharge, it is shown by various techniques that they also decompose and that decomposition increases while Li2O2 decreases on cycling (see picture). Thus, these electrolytes are not suitable. AU - Freunberger, Stefan Alexander AU - Chen, Yuhui AU - Drewett, Nicholas E. AU - Hardwick, Laurence J. AU - Bardé, Fanny AU - Bruce, Peter G. ID - 7314 IS - 37 JF - Angewandte Chemie International Edition SN - 1433-7851 TI - The Lithium-Oxygen battery with ether-based electrolytes VL - 50 ER - TY - JOUR AB - Lithium-metal oxides with a high formal Li2O content, such as Li5FeO4 (5Li2O•Fe2O3) and a Li2MnO3•LiFeO2 composite ({Li2O•MnO2}•{Li2O•Fe2O3}) have been explored as electrocatalysts for primary and rechargeable Li-O2 cells. Activation occurs predominantly by Li2O removal, either electrochemically or chemically by acid-treatment. Superior electrochemical behavior is obtained if activation occurs by acid-treatment; Li2MnO3•LiFeO2 catalysts provide 2516 mAh/g (carbon) corresponding to 931 mAh/g (electrocatalyst + carbon) during the initial discharge. The reaction is reasonably reversible during the early cycles. The approach has implications for designing electrocatalysts that participate through electrochemical Li2O extraction/reformation reactions, offering exceptionally high capacities. AU - Trahey, L. AU - Johnson, C. S. AU - Vaughey, J. T. AU - Kang, S.-H. AU - Hardwick, L. J. AU - Freunberger, Stefan Alexander AU - Bruce, P. G. AU - Thackeray, M. M. ID - 7317 IS - 5 JF - Electrochemical and Solid-State Letters SN - 1099-0062 TI - Activated Lithium-Metal-Oxides as catalytic electrodes for Li–O2 cells VL - 14 ER - TY - JOUR AB - The nonaqueous rechargeable lithium–O2 battery containing an alkyl carbonate electrolyte discharges by formation of C3H6(OCO2Li)2, Li2CO3, HCO2Li, CH3CO2Li, CO2, and H2O at the cathode, due to electrolyte decomposition. Charging involves oxidation of C3H6(OCO2Li)2, Li2CO3, HCO2Li, CH3CO2Li accompanied by CO2 and H2O evolution. Mechanisms are proposed for the reactions on discharge and charge. The different pathways for discharge and charge are consistent with the widely observed voltage gap in Li–O2 cells. Oxidation of C3H6(OCO2Li)2 involves terminal carbonate groups leaving behind the OC3H6O moiety that reacts to form a thick gel on the Li anode. Li2CO3, HCO2Li, CH3CO2Li, and C3H6(OCO2Li)2 accumulate in the cathode on cycling correlating with capacity fading and cell failure. The latter is compounded by continuous consumption of the electrolyte on each discharge. AU - Freunberger, Stefan Alexander AU - Chen, Yuhui AU - Peng, Zhangquan AU - Griffin, John M. AU - Hardwick, Laurence J. AU - Bardé, Fanny AU - Novák, Petr AU - Bruce, Peter G. ID - 7316 IS - 20 JF - Journal of the American Chemical Society SN - 0002-7863 TI - Reactions in the rechargeable Lithium–O2 battery with alkyl carbonate electrolytes VL - 133 ER - TY - JOUR AB - Spectroscopic data (see picture) provide direct evidence that in non‐aqueous Li+ electrolyte, O2 is reduced to O2−, which then forms LiO2 on the electrode surface which disproportionates to Li2O2. On charging, Li2O2 decomposes directly, in a one‐step reaction to evolve O2 and does not pass through LiO2 as an intermediate. AU - Peng, Zhangquan AU - Freunberger, Stefan Alexander AU - Hardwick, Laurence J. AU - Chen, Yuhui AU - Giordani, Vincent AU - Bardé, Fanny AU - Novák, Petr AU - Graham, Duncan AU - Tarascon, Jean-Marie AU - Bruce, Peter G. ID - 7315 IS - 28 JF - Angewandte Chemie International Edition SN - 1433-7851 TI - Oxygen reactions in a non-aqueous Li+ electrolyte VL - 50 ER - TY - CONF AB - Synchronous distributed algorithms are easier to design and prove correct than algorithms that tolerate asynchrony. Yet, in the real world, networks experience asynchrony and other timing anomalies. In this paper, we address the question of how to efficiently transform an algorithm that relies on synchronization into an algorithm that tolerates asynchronous executions. We introduce a transformation technique from synchronous algorithms to indulgent algorithms [1], which induces only a constant overhead in terms of time complexity in well-behaved executions. Our technique is based on a new abstraction we call an asynchrony detector, which the participating processes implement collectively. The resulting transformation works for a large class of colorless tasks, including consensus and set agreement. Interestingly, we also show that our technique is relevant for colored tasks, by applying it to the renaming problem, to obtain the first indulgent renaming algorithm. AU - Alistarh, Dan-Adrian AU - Gilbert, Seth AU - Guerraoui, Rachid AU - Travers, Corentin ID - 757 TI - Generating fast indulgent algorithms VL - 6522 LNCS ER - TY - CONF AB - We study the complexity of renaming, a fundamental problem in distributed computing in which a set of processes need to pick distinct names from a given namespace. We prove an individual lower bound of Ω(k) process steps for deterministic renaming into any namespace of size sub-exponential in k, where k is the number of participants. This bound is tight: it draws an exponential separation between deterministic and randomized solutions, and implies new tight bounds for deterministic fetch-and-increment registers, queues and stacks. The proof of the bound is interesting in its own right, for it relies on the first reduction from renaming to another fundamental problem in distributed computing: mutual exclusion. We complement our individual bound with a global lower bound of Ω(k log (k/c)) on the total step complexity of renaming into a namespace of size ck, for any c ≥ 1. This applies to randomized algorithms against a strong adversary, and helps derive new global lower bounds for randomized approximate counter and fetch-and-increment implementations, all tight within logarithmic factors. AU - Alistarh, Dan-Adrian AU - Aspnes, James AU - Gilbert, Seth AU - Guerraoui, Rachid ID - 759 TI - The complexity of renaming ER - TY - CONF AB - We give two new randomized algorithms for strong renaming, both of which work against an adaptive adversary in asynchronous shared memory. The first uses repeated sampling over a sequence of arrays of decreasing size to assign unique names to each of n processes with step complexity O(log3 n). The second transforms any sorting network into a strong adaptive renaming protocol, with an expected cost equal to the depth of the sorting network. Using an AKS sorting network, this gives a strong adaptive renaming algorithm with step complexity O(log k), where k is the contention in the current execution. We show this to be optimal based on a classic lower bound of Jayanti. We also show that any such strong renaming protocol can be used to build a monotone-consistent counter with logarithmic step complexity (at the cost of adding a max register) or a linearizable fetch-and-increment register (at the cost of increasing the step complexity by a logarithmic factor). AU - Alistarh, Dan-Adrian AU - Aspnes, James AU - Censor Hillel, Keren AU - Gilbert, Seth AU - Zadimoghaddam, Morteza ID - 761 TI - Optimal-time adaptive strong renaming, with applications to counting ER - TY - CONF AB - A randomized implementation is given of a test-and-set register with O(log log n) individual step complexity and O(n) total step complexity against an oblivious adversary. The implementation is linearizable and multi-shot, and shows an exponential complexity improvement over previous solutions designed to work against a strong adversary. AU - Alistarh, Dan-Adrian AU - Aspnes, James ID - 760 TI - Sub-logarithmic test-and-set against a weak adversary VL - 6950 LNCS ER - TY - JOUR AU - Robinson, Matthew Richard ID - 7750 IS - 6 JF - Behavioral Ecology SN - 1465-7279 TI - Understanding intrasexual competition and sexual selection requires an evolutionary ecology framework VL - 22 ER - TY - JOUR AB - Chandelier (axoaxonic) cells (ChCs) are a distinct group of GABAergic interneurons that innervate the axon initial segments of pyramidal cells. However, their circuit role and the function of their clearly defined anatomical specificity remain unclear. Recent work has demonstrated that chandelier cells can produce depolarizing GABAergic PSPs, occasionally driving postsynaptic targets to spike. On the other hand, other work suggests that ChCs are hyperpolarizing and may have an inhibitory role. These disparate functional effects may reflect heterogeneity among ChCs. Here, using brain slices from transgenic mouse strains, we first demonstrate that, across different neocortical areas and genetic backgrounds, upper Layer 2/3 ChCs belong to a single electrophysiologically and morphologically defined population, extensively sampling Layer 1 inputs with asymmetric dendrites. Consistent with being a single cell type, we find electrical coupling between ChCs. We then investigate the effect of chandelier cell activation on pyramidal neuron spiking in several conditions, ranging from the resting membrane potential to stimuli designed to approximate in vivo membrane potential dynamics. We find that under quiescent conditions, chandelier cells are capable of both promoting and inhibiting spike generation, depending on the postsynaptic membrane potential. However, during in vivo-like membrane potential fluctuations, the dominant postsynaptic effect was a strong inhibition. Thus, neocortical chandelier cells, even from within a homogeneous population, appear to play a dual role in the circuit, helping to activate quiescent pyramidal neurons, while at the same time inhibiting active ones. AU - Woodruff, A. R. AU - McGarry, L. M. AU - Vogels, Tim P AU - Inan, M. AU - Anderson, S. A. AU - Yuste, R. ID - 8025 IS - 49 JF - Journal of Neuroscience SN - 0270-6474 TI - State-dependent function of neocortical chandelier cells VL - 31 ER -