Search results for "REVERSAL"
showing 10 items of 72 documents
Ultrafast Optical Demagnetization manipulates Nanoscale Spin Structure in Domain Walls
2012
During ultrafast demagnetization of a magnetically ordered solid, angular momentum has to be transferred between the spins, electrons, and phonons in the system on femto- and picosecond timescales. Although the intrinsic spin-transfer mechanisms are intensely debated, additional extrinsic mechanisms arising due to nanoscale heterogeneity have only recently entered the discussion. Here we use femtosecond X-ray pulses from a free-electron laser to study thin film samples with magnetic domain patterns. We observe an infrared-pump-induced change of the spin structure within the domain walls on the sub-picosecond timescale. This domain-topography-dependent contribution connects the intrinsic dem…
Finitary Representations and Images of Transitive Finitary Permutation Groups
1999
Abstract We characterize the point stabilizers and kernels of finitary permutation representations of infinite transitive groups of finitary permutations. Moreover, the number of such representations is determined.
Energy generation and abatement of Acid Orange 7 in reverse electrodialysis cells using salinity gradients
2015
Abstract The simultaneous generation of electric energy and the treatment of wastewaters contaminated by an organic pollutant resistant to conventional biological processes, Acid Orange 7 (AO7), was achieved for the first time using proper redox processes by reverse electrodialysis using salinity gradients. The stack was fed with two aqueous solutions with different concentrations of NaCl and a synthetic wastewater contaminated by AO7. Various electrochemical approaches including electro-Fenton, electrogeneration of active chlorine (IOAC) and coupled process were performed in a stack equipped with 40–60 cell pairs and studied by focused electrolyses. The effect of the number of cell pairs a…
On the Greedy Algorithm for the Shortest Common Superstring Problem with Reversals
2015
We study a variation of the classical Shortest Common Superstring (SCS) problem in which a shortest superstring of a finite set of strings $S$ is sought containing as a factor every string of $S$ or its reversal. We call this problem Shortest Common Superstring with Reversals (SCS-R). This problem has been introduced by Jiang et al., who designed a greedy-like algorithm with length approximation ratio $4$. In this paper, we show that a natural adaptation of the classical greedy algorithm for SCS has (optimal) compression ratio $\frac12$, i.e., the sum of the overlaps in the output string is at least half the sum of the overlaps in an optimal solution. We also provide a linear-time implement…
Quantum lower bound for inverting a permutation with advice
2014
Given a random permutation $f: [N] \to [N]$ as a black box and $y \in [N]$, we want to output $x = f^{-1}(y)$. Supplementary to our input, we are given classical advice in the form of a pre-computed data structure; this advice can depend on the permutation but \emph{not} on the input $y$. Classically, there is a data structure of size $\tilde{O}(S)$ and an algorithm that with the help of the data structure, given $f(x)$, can invert $f$ in time $\tilde{O}(T)$, for every choice of parameters $S$, $T$, such that $S\cdot T \ge N$. We prove a quantum lower bound of $T^2\cdot S \ge \tilde{\Omega}(\epsilon N)$ for quantum algorithms that invert a random permutation $f$ on an $\epsilon$ fraction of…
Commentary: "Nitric oxide releases Cl(-) from acidic organelles in retinal amacrine cells".
2015
In their recent article (Krishnan and Gleason, 2015) Vijai Krishnan and Evanna Gleason investigate the cellular mechanisms underlying the shift in the GABA reversal potential upon application of nitric oxide (NO). Functional alteration in GABAergic signaling by alterations in the GABA reversal potential has been identified as an important mechanism of plasticity (Raimondo et al., 2012) and NO is clearly one key substance involved in plasticity (Prast and Philippu, 2001). Therefore, the investigation of the mechanisms behind the NO induced shift in GABAergic effects is an important issue. However, in my opinion the authors neglected a possible explanation of their observations in the discuss…
Measurement of CP asymmetry in D 0 → K - K + and D 0 → π - πdecays
2014
Time-integrated $CP$ asymmetries in $D^0$ decays to the final states $K^- K^+$ and $\pi^- \pi^+$ are measured using proton-proton collisions corresponding to $3\mathrm{\,fb}^{-1}$ of integrated luminosity collected at centre-of-mass energies of $7\mathrm{\,Te\kern -0.1em V}$ and $8\mathrm{\,Te\kern -0.1em V}$. The $D^0$ mesons are produced in semileptonic $b$-hadron decays, where the charge of the accompanying muon is used to determine the initial flavour of the charm meson. The difference in $CP$ asymmetries between the two final states is measured to be \begin{align} \Delta A_{CP} = A_{CP}(K^-K^+)-A_{CP}(\pi^-\pi^+) = (+0.14 \pm 0.16\mathrm{\,(stat)} \pm 0.08\mathrm{\,(syst)})\% \ . \nonu…
Controlling the cohesion of cement paste
2005
The main source of cohesion in cement paste is the nanoparticles of calcium silicate hydrate (C-S-H), which are formed upon the dissolution of the original tricalcium silicate (C(3)S). The interaction between highly charged C-S-H particles in the presence of divalent calcium counterions is strongly attractive because of ion-ion correlations and a negligible entropic repulsion. Traditional double-layer theory based on the Poisson-Boltzmann equation becomes qualitatively incorrect in these systems. Monte Carlo (MC) simulations in the framework of the primitive model of electrolyte solution is then an alternative, where ion-ion correlations are properly included. In addition to divalent calciu…
Can re-regulation of the financial sector strike back public debt?
2015
This paper analyzes the impact of financial sector policy changes on the dynamics of public debt. Using a panel of 89 countries from 1973 to 2005, we find that while the implementation of (large) financial liberalisation policies significantly raises the public debt growth rate, the adoption of financial re-regulation measures leads to a mild reduction of public debt. Looking at the different typologies of financial sector policy changes, we show that stricter banking supervision, privatisations and restrictions to international capital flows contribute to a fast decline of the growth rate of public debt. In contrast, the removal of entry barriers and the elimination of interest rate contro…
Sex roles and the evolution of parental care specialization
2019
Males and females are defined by the relative size of their gametes (anisogamy), but secondary sexual dimorphism in fertilization, parental investment and mating competition is widespread and often remarkably stable over evolutionary timescales. Recent theory has clarified the causal connections between anisogamy and the most prevalent differences between the sexes, but deviations from these patterns remain poorly understood. Here, we study how sex differences in parental investment and mating competition coevolve with parental care specialization. Parental investment often consists of two or more distinct activities (e.g. provisioning and defence) and parents may care more efficiently by s…