Proposal for a Topological Plasmon Spin Rectifier

We propose a device in which the spin-polarized AC plasmon mode in the surface state of a topological insulator nanostructure induces a static spin accumulation in a resonant, normal metal structure coupled to it. Using a finite-difference time-domain model, we simulate this spin-pump mechanism with drift, diffusion, relaxation, and precession in a magnetic field. This optically-driven system can serve as a DC "spin battery" for spintronic devices.Comment: Eq. 1 corrected; Figs 3 and 4 update

‘Dickens and the Middle-Class Weekly’

The 1830s saw an upsurge in cheap miscellanies of general reading material for the broadest of readerships. From the outset of his career, Charles Dickens was fascinated by the possibilities of addressing such an audience, but not until 1850, with his founding of the 2d. weekly magazine, Household Words, did he achieve his ambition of editing such a periodical. The chapter traces the development of this project, and shows how Dickens embraced hybridity of form and content to establish a secure place for his new journal in the crowded mid-century marketplace, one that straddled class identifiers. In 1859, the journal was incorporated into a new publication, All the Year Round, which carried an instalment of serial fiction as the opening article, rather than a specially-written leader. The switch anticipated the establishment of a series of upmarket monthlies that also privileged fiction over journalism, and gave Dickens and his sub-editor the opportunity to establish early readerships for their brand abroad—in Europe, the colonies, and above all in America. Two postscripts to the chapter outline the afterlife of Dickens’s weeklies following his death in 1870, and their resurrection, in digital form, in the twenty-first century

Electron spin relaxation in organic semiconductors probed through muSR

Muon spin spectroscopy and in particular the avoided level crossing technique is introduced, with the aim of showing it as a very sensitive local probe for electron spin relaxation in organic semiconductors. Avoided level crossing data on TMS-pentacene at different temperatures are presented, and they are analysed to extract the electron spin relaxation rate, that is shown to increase on increasing the temperature from 0.02 MHz to 0.33 MHz at 3 K and 300 K respectively.Comment: International Conference TSN2010 "Trends in spintronics and nanomagnetism

How should we interpret the two transport relaxation times in the cuprates ?

We observe that the appearance of two transport relaxation times in the various transport coefficients of cuprate metals may be understood in terms of scattering processes that discriminate between currents that are even, or odd under the charge conjugation operator. We develop a transport equation that illustrates these ideas and discuss its experimental and theoretical consequences.Comment: 19 pages, RevTeX with 8 postscript figures included. To appear in ``Non Fermi Liquid Physics'', J. Phys:Cond. Matt. (1997

Singular value decomposition applied to compact binary coalescence gravitational-wave signals

We investigate the application of the singular value decomposition to compact-binary, gravitational-wave data-analysis. We find that the truncated singular value decomposition reduces the number of filters required to analyze a given region of parameter space of compact binary coalescence waveforms by an order of magnitude with high reconstruction accuracy. We also compute an analytic expression for the expected signal-loss due to the singular value decomposition truncation.Comment: 4 figures, 6 page

Spike-timing computation properties of a feed-forward neural network model

Brain function is characterized by dynamical interactions among networks of neurons. These interactions are mediated by network topology at many scales ranging from microcircuits to brain areas. Understanding how networks operate can be aided by understanding how the transformation of inputs depends upon network connectivity patterns, e.g. serial and parallel pathways. To tractably determine how single synapses or groups of synapses in such pathways shape transformations, we modeled feed-forward networks of 7-22 neurons in which synaptic strength changed according to a spike-timing dependent plasticity rule. We investigated how activity varied when dynamics were perturbed by an activity-dependent electrical stimulation protocol (spike-triggered stimulation; STS) in networks of different topologies and background input correlations. STS can successfully reorganize functional brain networks in vivo, but with a variability in effectiveness that may derive partially from the underlying network topology. In a simulated network with a single disynaptic pathway driven by uncorrelated background activity, structured spike-timing relationships between polysynaptically connected neurons were not observed. When background activity was correlated or parallel disynaptic pathways were added, however, robust polysynaptic spike timing relationships were observed, and application of STS yielded predictable changes in synaptic strengths and spike-timing relationships. These observations suggest that precise input-related or topologically induced temporal relationships in network activity are necessary for polysynaptic signal propagation. Such constraints for polysynaptic computation suggest potential roles for higher-order topological structure in network organization, such as maintaining polysynaptic correlation in the face of relatively weak synapses