Effect of population-based training programs on bystander willingness to perform cardiopulmonary resuscitation

Objective. This study was performed to determine the factors related to unwillingness of bystanders to perform cardiopulmonary resuscitation (CPR), and improvement of willingness among the lay public after CPR training. Design. Retrospective design Methods. We collected questionnaires received from laypersons attending CPR training courses implemented by the CPR Improvement Program of Chang Gung Memorial Foundation. Pre- and post-training questionnaires were given to participants attending CPR training courses between September 2013 and January 2014. Results. Among the 401 respondents at pre-training, higher educational level (odds ratio, 3.605; 95% confidence interval [CI], 3.055 – 8.284) and previous CPR training (odds ratio, 1.754; 95% CI, 1.049 – 2.932) were significantly associated with willingness to perform bystander CPR. Significant improvements in willingness to perform conventional CPR and hands-only CPR on a stranger were observed after training (P = 0.016 and P < 0.0001, respectively). Approximately half of the respondents claimed that fear of doing further harm was the primary reason for their lack of willingness to administer conventional CPR on a stranger. Conclusions. We showed that CPR training significantly increased the rate of willingness to perform CPR on strangers as well as acquaintances among the lay public. This study also showed that fear of doing further harm was the most significant barrier after training. This concern should be addressed in future training programs

Quantum Oscillation Signatures of Fermi Arcs in Tunnel Magnetoconductance

Fermi-arc surface states of Weyl semimetals exhibit a unique combination of localization to a surface and connectivity to the bulk Weyl fermions that can move along the localization direction. We predict anomalous quantum-oscillation signatures of Fermi arcs in the tunnel mangetoconductance across an interface between two Weyl semimetals. These oscillations stem from a momentum-space analog of Aharonov-Bohm interference of electrons moving along the interface Fermi arcs, driven by an external magnetic field normal to the interface. The Fermi arcs' connectivity to the bulk enables their characterization via transport normal to the interface, while their localization manifests in a strong field-angle anisotropy of the oscillations. This combination distinguishes these anomalous oscillations from conventional Shubnikov-de Haas oscillations and makes them identifiable even in complex oscillation spectra of real materials.Comment: 4 + 6 page

Magnetic breakdown and chiral magnetic effect at Weyl-semimetal tunnel junctions

We investigate magnetotransport across an interface between two Weyl semimetals whose Weyl nodes project onto different interface momenta. Such an interface generically hosts Fermi arcs that connect Weyl nodes of identical chirality in different Weyl semimetals (homochiral connectivity)—in contrast to surface Fermi arcs that connect opposite-chirality Weyl nodes within the same Weyl semimetal (heterochiral connectivity). We show that electron transport along homochiral-connectivity Fermi arcs, in the presence of a longitudinal magnetic field, results in a universal longitudinal magnetoconductance of e2/h per magnetic flux quantum. Furthermore, a weak tunnel coupling can result in a close encounter of two homochiral-connectivity Fermi arcs, enabling magnetic breakdown. Above the breakdown field the interface Fermi arc connectivity is effectively heterochiral, leading to a saturation of the conductance

Magnetic Breakdown and Chiral Magnetic Effect at Weyl-Semimetal Tunnel Junctions

We investigate magnetotransport across an interface between two Weyl semimetals whose Weyl nodes project onto different interface momenta. Such an interface generically hosts Fermi arcs that connect Weyl nodes of identical chirality in different Weyl semimetals (homochiral connectivity) -- in contrast to surface Fermi arcs that connect opposite-chirality Weyl nodes within the same Weyl semimetal (heterochiral connectivity). We show that electron transport along the arcs with homochiral connectivity, in the presence of a longitudinal magnetic field, leads to a universal longitudinal magnetoconductance of $e^2/h$ per magnetic flux quantum. Furthermore, a weak tunnel coupling can result in a close encounter of two homochiral-connectivity Fermi arcs, enabling magnetic breakdown. Above the breakdown field the interface Fermi arc connectivity is effectively heterochiral, leading to a saturation of the conductance

Refining and relating fundamentals of functional theory

To advance the foundation of one-particle reduced density matrix functional theory (1RDMFT) we refine and relate some of its fundamental features and underlying concepts. We define by concise means the scope of a 1RDMFT, identify its possible natural variables and explain how symmetries could be exploited. In particular, for systems with time-reversal symmetry, we explain why there exist six equivalent universal functionals, prove concise relations among them and conclude that the important notion of $v$-representability is relative to the scope and choice of variable. All these fundamental concepts are then comprehensively discussed and illustrated for the Hubbard dimer and its generalization to arbitrary pair interactions $W$. For this, we derive by analytical means the pure and ensemble functionals with respect to both the real- and complex-valued Hilbert space. The comparison of various functionals allows us to solve the underlying $v$-representability problems analytically and the dependence of its solution on the pair interaction is demonstrated. Intriguingly, the gradient of each universal functional is found to always diverge repulsively on the boundary of the domain. In that sense, this key finding emphasizes the universal character of the fermionic exchange force, recently discovered and proven in the context of translationally-invariant one-band lattice models

Refining and relating fundamentals of functional theory

To advance the foundation of one-particle reduced density matrix functional theory (1RDMFT), we refine and relate some of its fundamental features and underlying concepts. We define by concise means the scope of a 1RDMFT, identify its possible natural variables, and explain how symmetries could be exploited. In particular, for systems with time-reversal symmetry, we explain why there exist six equivalent universal functionals, prove concise relations among them, and conclude that the important notion of v-representability is relative to the scope and choice of variable. All these fundamental concepts are then comprehensively discussed and illustrated for the Hubbard dimer and its generalization to arbitrary pair interactions W. For this, we derive by analytical means the pure and ensemble functionals with respect to both the real- and complex-valued Hilbert space. The comparison of various functionals allows us to solve the underlying v-representability problems analytically, and the dependence of its solution on the pair interaction is demonstrated. Intriguingly, the gradient of each universal functional is found to always diverge repulsively on the boundary of the domain. In that sense, this key finding emphasizes the universal character of the fermionic exchange force, recently discovered and proven in the context of translationally invariant one-band lattice models

Hinge states of second-order topological insulators as a Mach-Zehnder interferometer

Three-dimensional higher-order topological insulators can have topologically protected chiral modes propagating on their hinges. Hinges with two copropagating chiral modes can serve as a “beam splitter” between hinges with only a single chiral mode. Here we show how such a crystal, with Ohmic contacts attached to its hinges, can be used to realize a Mach-Zehnder interferometer. We present concrete calculations for a lattice model of a first-order topological insulator in a magnetic field, which, for a suitable choice of parameters, is an extrinsic second-order topological insulator with the required configuration of chiral hinge modes

Evaluating a peer-to-peer storage system in presence of malicious peers

International audienceWe present a peer-to-peer based storage system and evaluate its resistance in the presence of malicious peers. To do so, we resort to simulation of the actual code borrowed from the production system. Our analysis allows to identify the main threats, prioritise them and propose directions for mitigating the attacks

Synthesis and characterisation of Li11RE18M4O39−δ: RE = Nd or Sm; M = Al, Co or Fe

Four new phases of general formula, Li11RE18M4O39−δ: REM = NdAl, NdCo, SmCo, SmFe, have been synthesised and characterised. The NdAl phase, and probably the others, is isostructural with the NdFe analogue, but some cation disorder and partial site occupancies prevent full structural refinement of powder neutron diffraction data. The NdCo phase also forms a solid solution with variable Li content (and charge compensation by either oxygen vacancies or variable transition metal oxidation state). The NdAl phase is a modest conductor of Li+ ions whereas the other three phases are electronic conductors, attributed to mixed valence of the transition metal ions. Subsolidus phase diagrams for the systems Li2O–Nd2O3– Al2O3, ‘CoO’ have been determined and an additional new phase, LiCoNd4O8, which appears to have a K2NiF4-related superstructure, identified

A study on the influence of lithium plating on battery degradation

Within Li-ion batteries, lithium plating is considered as one of the main reasons behind the capacity fade that occurs during low temperature and fast charging conditions. Previous studies indicate that plating is influenced by the levels of loss of lithium inventory (LLI) and the loss of active material (LAM) present in a battery. However, it is not clear from the literature on how lithium plating influences battery degradation in terms of LAM and LLI. Quantifying the undesirable impacts of lithium plating can help in understanding its impact on battery degradation and feedback effects of previous lithium plating on the formation of present plating. This study aims to quantify the degradation modes of lithium plating: LLI, LAM at the electrode level. A commercial Li-ion cell was first, aged using two different cases: with and without lithium plating. Second, a degradation diagnostic method is developed to quantify the degradation modes based on their measurable effects on open-circuit voltage (OCV) and cell capacity. The results highlight that LAMNE and LLI levels under the fast charge profile are increased by 10% and 12%, respectively, compared to those under the less aggressive charge profile. Further, limitations of the degradation analysis methods are discussed