7,341 research outputs found
Spin and Orbital Splitting in Ferromagnetic Contacted Single Wall Carbon Nanotube Devices
We observed the coulomb blockade phenomena in ferromagnetic contacting single
wall semiconducting carbon nanotube devices. No obvious Coulomb peaks shift was
observed with existing only the Zeeman splitting at 4K. Combining with other
effects, the ferromagnetic leads prevent the orbital spin states splitting with
magnetic field up to 2 Tesla at 4K. With increasing magnetic field further,
both positive or negative coulomb peaks shift slopes are observed associating
with clockwise and anticlockwise orbital state splitting. The strongly
suppressed/enhanced of the conductance has been observed associating with the
magnetic field induced orbital states splitting/converging
Spectroscopic and redox properties of amine-unctionalized K_2[Os-^(II)(bpy)(CN)_4] complexes
We report the first examples of amine-functionalized K_2[Os^(II)(bpy)(CN)_4] (bpy = 2,2'-bipyridine) complexes. The tetracyanoosmate complexes were prepared by UV irradiation (λ = 254 nm) of K_4[Os^(II)(CN)_6] and primary amine-functionalized bpy ligands in acidic aqueous media. The aqueous solution pH dependences of the spectroscopic and redox properties of 4,4'- and 5,5'-substituted complexes have been investigated. The pendant amine functional groups and coordinated cyanide ligands are basic sites that can be sequentially protonated, thereby allowing systematic tuning of electrochemical and optical spectroscopic properties
Excitation lines and the breakdown of Stokes-Einstein relations in supercooled liquids
By applying the concept of dynamical facilitation and analyzing the
excitation lines that result from this facilitation, we investigate the origin
of decoupling of transport coefficients in supercooled liquids. We illustrate
our approach with two classes of models. One depicts diffusion in a strong
glass former, and the other in a fragile glass former. At low temperatures,
both models exhibit violation of the Stokes-Einstein relation,
, where is the self diffusion constant and is the
structural relaxation time. In the strong case, the violation is sensitive to
dimensionality , going as for , and as for . In the fragile case, however, we argue that
dimensionality dependence is weak, and show that for , . This scaling for the fragile case compares favorably with the
results of a recent experimental study for a three-dimensional fragile glass
former.Comment: 7 pages, 7 figures, submitted to Phys. Rev.
Classifying LISA gravitational wave burst signals using Bayesian evidence
We consider the problem of characterisation of burst sources detected with
the Laser Interferometer Space Antenna (LISA) using the multi-modal nested
sampling algorithm, MultiNest. We use MultiNest as a tool to search for
modelled bursts from cosmic string cusps, and compute the Bayesian evidence
associated with the cosmic string model. As an alternative burst model, we
consider sine-Gaussian burst signals, and show how the evidence ratio can be
used to choose between these two alternatives. We present results from an
application of MultiNest to the last round of the Mock LISA Data Challenge, in
which we were able to successfully detect and characterise all three of the
cosmic string burst sources present in the release data set. We also present
results of independent trials and show that MultiNest can detect cosmic string
signals with signal-to-noise ratio (SNR) as low as ~7 and sine-Gaussian signals
with SNR as low as ~8. In both cases, we show that the threshold at which the
sources become detectable coincides with the SNR at which the evidence ratio
begins to favour the correct model over the alternative.Comment: 21 pages, 11 figures, accepted by CQG; v2 has minor changes for
consistency with accepted versio
Metal matrix composite materials
COMPOSITF materials, especially metal matrix composite
materials are possible substitutes for metals in use today. However, because they can possess extremely high strengths, moduli and excellent high temperature prop-erties they may be employed most profitably in applicat-ions which do not presently exist,since no present mat-erial has the required capabilities.In addition, their present high cost and very early stage of development
make them unlikely candidates for materials substitut-
ion in the context of this meeting. This paper is orie-nted more towards the development of composite materials for aerospace structures
Financial phantasmagoria: corporate image-work in times of crisis
Our purpose in this article is to relate the real movements in the economy during 2008 to the ?image-work? of financial institutions. Over the period January?December 2008 we collected 241 separate advertisements from 61 financial institutions published in the Financial Times. Reading across the ensemble of advertisements for themes and evocative images provides an impression of the financial imaginaries created by these organizations as the global financial crisis unfolded. In using the term ?phantasmagoria? we move beyond its colloquial sense of a set of strange images designed to dazzle towards the more technical connotation used by Ranci�re (2004) who suggested that words and images can offer a trace of an overall determining set-up if they are torn from their obviousness so they become phantasmagoric figures. The key phantasmagoric figure we identify here is that of the financial institution as timeless, immortal and unchanging; a coherent and autonomous entity amongst other actors. This notion of uniqueness belies the commonality of thinking which precipitated the global financial crisis as well as the limited capacity for control of financial institutions in relation to market events. It also functions as a powerful naturalizing force, making it hard to question certain aspects of the recent period of ?capitalism in crisis?
From Scepticism to Liberalism? Bernard Williams, the Foundations of Liberalism and Political Realism.
Bernard Williams was an ethical sceptic, but he was also a proponent of liberalism. To what extent can one finally be both? This article explores this question through a particular emphasis on Williams, but seeks to draw wider lessons regarding what ethical scepticism should and should not amount to. It shows how ethical scepticism can be reconciled with a commitment to what Williams, following Judith Shklar, called ‘the liberalism of fear’, which is revealed as an ecumenical outlook for different stripes of ethical sceptic. The article concludes by drawing some lessons for the recent ‘realist’ turn in political theory.Research for this article was undertaken while I was the recipient of an Arts and Humanities Research Council PhD studentship at the University of Cambridge, and was later supported by the Cambridge Faculty of History’s Prince Consort and Thirlwall fund
Memory difficulties are not always a sign of incipient dementia: a review of the possible causes of loss of memory efficiency
n/
Statics and dynamics of domain patterns in hexagonal-orthorhombic ferroelastics
We study the statics and the dynamics of domain patterns in proper
hexagonal-orthorhombic ferroelastics; these patterns are of particular interest
because they provide a rare physical realization of disclinations in crystals.
Both our static and dynamical theories are based entirely on classical,
nonlinear elasticity theory; we use the minimal theory consistent with
stability, symmetry and ability to explain qualitatively the observed patterns.
After scaling, the only parameters of the static theory are a temperature
variable and a stiffness variable. For moderate to large stiffness, our static
results show nested stars, unnested stars, fans and other nodes, triangular and
trapezoidal regions of trapped hexagonal phase, etc observed in electron
microscopy of Ta4N and Mg-Cd alloys, and also in lead orthovanadate (which is
trigonal-monoclinic); we even find imperfections in some nodes, like those
observed. For small stiffness, we find patterns like those observed in the
mineral Mg-cordierite. Our dynamical studies of growth and relaxation show the
formation of these static patterns, and also transitory structures such as
12-armed bursts, streamers and striations which are also seen experimentally.
The major aspects of the growth-relaxation process are quite unlike those in
systems with conventional order parameters, for it is inherently nonlocal; for
example, the changes from one snapshot to the next are not predictable by
inspection.Comment: 9 pages, 3 figures (1 b&w, 2 colour); animations may be viewed at
http://huron.physics.utoronto.ca/~curnoe/sim.htm
Gravitational wave radiometry: Mapping a stochastic gravitational wave background
The problem of the detection and mapping of a stochastic gravitational wave
background (SGWB), either of cosmological or astrophysical origin, bears a
strong semblance to the analysis of CMB anisotropy and polarization. The basic
statistic we use is the cross-correlation between the data from a pair of
detectors. In order to `point' the pair of detectors at different locations one
must suitably delay the signal by the amount it takes for the gravitational
waves (GW) to travel to both detectors corresponding to a source direction.
Then the raw (observed) sky map of the SGWB is the signal convolved with a beam
response function that varies with location in the sky. We first present a
thorough analytic understanding of the structure of the beam response function
using an analytic approach employing the stationary phase approximation. The
true sky map is obtained by numerically deconvolving the beam function in the
integral (convolution) equation. We adopt the maximum likelihood framework to
estimate the true sky map that has been successfully used in the broadly
similar, well-studied CMB map making problem. We numerically implement and
demonstrate the method on simulated (unpolarized) SGWB for the radiometer
consisting of the LIGO pair of detectors at Hanford and Livingston. We include
`realistic' additive Gaussian noise in each data stream based on the LIGO-I
noise power spectral density. The extension of the method to multiple baselines
and polarized GWB is outlined. In the near future the network of GW detectors,
including the Advanced LIGO and Virgo detectors that will be sensitive to
sources within a thousand times larger spatial volume, could provide promising
data sets for GW radiometry.Comment: 24 pages, 19 figures, pdflatex. Matched version published in Phys.
Rev. D - minor change
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