6,146 research outputs found
Effect of Polyethylene Glycol Treatment on Acetic Acid Emissions from Wood
Acetic acid is known to be emitted from sound wood and can accelerate damage to heritage materials, particularly metals. However, few studies have investigated the extent of acetic acid emissions from archaeological wood. This research utilised Solid-Phase-Micro-Extraction (SPME) GC–MS and lead coupon corrosion to identify volatile emissions from polyethylene glycol (PEG)-treated archaeological wood from the Mary Rose collection and assess if they could cause accelerated damage. In addition, the effect of PEG treatment on acetic acid emissions was investigated using sound wood samples. For sound wood, the PEG treatment acted as a barrier to acetic acid emissions, with higher-molecular-weight PEGs preventing more emissions. Archaeological wood, despite its age and high-molecular-weight PEG treatment, still emitted detectable concentrations of acetic acid. Moreover, they emitted a wider array of compounds compared to sound wood, including carbon disulphide. Like sound wood, when the archaeological wood samples were in a sealed environment with lead coupons, they caused accelerated corrosion to lead. This evidences that archaeological wood can emit high enough concentrations of volatile compounds to cause damage and further investigation should be performed to evaluate if this can occur inside museum display cases
Correlated magnetic noise in global networks of gravitational-wave detectors: Observations and implications
One of the most ambitious goals of gravitational-wave astronomy is to observe the stochastic gravitational-wave background. Correlated noise in two or more detectors can introduce a systematic error, which limits the sensitivity of stochastic searches. We report on measurements of correlated magnetic noise from Schumann resonances at the widely separated LIGO and Virgo detectors. We investigate the effect of this noise on a global network of gravitational-wave detectors and derive a constraint on the allowable coupling of environmental magnetic fields to test mass motion in gravitational-wave detectors. We find that while correlated noise from global electromagnetic fields could be safely ignored for initial LIGO stochastic searches, it could severely impact Advanced LIGO, Advanced Virgo, KAGRA, as well as third-generation detectors
Colloid-stabilized emulsions: behaviour as the interfacial tension is reduced
We present confocal microscopy studies of novel particle-stabilized
emulsions. The novelty arises because the immiscible fluids have an accessible
upper critical solution temperature. The emulsions have been created by
beginning with particles dispersed in the single-fluid phase. On cooling,
regions of the minority phase nucleate. While coarsening these nuclei become
coated with particles due to the associated reduction in interfacial energy.
The resulting emulsion is arrested, and the particle-coated interfaces have
intriguing properties. Having made use of the binary-fluid phase diagram to
create the emulsion we then make use of it to study the properties of the
interfaces. As the emulsion is re-heated toward the single-fluid phase the
interfacial tension falls and the volume of the dispersed phase drops.
Crumpling, fracture or coalescence can follow. The results show that the
elasticity of the interfaces has a controlling influence over the emulsion
behaviour.Comment: Submitted for the proceedings of the 6th Liquid Matter Conference,
held in Utrecht (NL) in July 200
Encapsulation of phosphorus dopants in silicon for the fabrication of a quantum computer
The incorporation of phosphorus in silicon is studied by analyzing phosphorus
delta-doped layers using a combination of scanning tunneling microscopy,
secondary ion mass spectrometry and Hall effect measurements. The samples are
prepared by phosphine saturation dosing of a Si(100) surface at room
temperature, a critical annealing step to incorporate phosphorus atoms, and
subsequent epitaxial silicon overgrowth. We observe minimal dopant segregation
(5 nm), complete electrical activation at a silicon growth temperature of 250
degrees C and a high two-dimensional electron mobility of 100 cm2/Vs at a
temperature of 4.2 K. These results, along with preliminary studies aimed at
further minimizing dopant diffusion, bode well for the fabrication of
atomically precise dopant arrays in silicon such as those found in recent
solid-state quantum computer architectures.Comment: 3 pages, 4 figure
Sleep quality is associated with emotion experience and adaptive regulation of positive emotion: An experience sampling study
Poor sleep patterns have been strongly linked to disrupted emotional experiences. Emotion regulation, defined as the capacity to manage one's own emotional responses, comprises strategies to increase, maintain, or decrease the intensity, duration, and trajectory of positive and negative emotions. Poor sleep has been identified as a risk factor for emotional dysregulation, but most of the focus has been on negative emotion regulation. We therefore asked whether natural variations in sleep are associated with the experience and regulation of both positive and negative emotion. Young adults, aged between 18–24 years (N = 101), completed 7 days of ecological momentary assessments using a smartphone application. Duration and quality of the previous night's sleep was reported each morning. Levels of positive and negative emotions, and strategies used to regulate emotions, were measured at pseudorandom timepoints four times a day. Multilevel modelling indicated that higher self-reported sleep quality was significantly associated with increased intensity and duration of positive emotion, and decreased intensity of negative emotion. There were no statistically significant associations between sleep duration and emotion intensity or duration. Sleep quality, and not sleep duration, was also associated with the reported use of positive emotion regulation strategies. For negative emotion regulation strategy use, we found no associations with sleep quality or duration. Naturally occurring fluctuations in daily sleep quality may be important for the experience and regulation of positive emotion in young adults. These findings emphasise the need to examine both positive and negative emotion, and emotion regulation to understand the links between sleep and mood
A Single-Photon-compatible Telecom-C-Band Quantum Memory in a Hot Atomic Gas
The efficient storage and on-demand retrieval of quantum optical states that
are compatible with the telecommunications C-band is a requirement for future
terrestrial-based quantum optical networking. Spectrum in the C-band minimises
optical fiber-propagation losses, and broad optical bandwidth facilitates
high-speed networking protocols. Here we report on a telecommunication
wavelength and bandwidth compatible quantum memory. Using the Off-Resonant
Cascaded Absorption protocol in hot Rb vapour, we demonstrate a total
memory efficiency of with a Doppler-limited storage time of
ns. We characterise the memory performance with weak coherent
states, demonstrating signal-to-noise ratios greater than unity for mean photon
number inputs above per pulse
Langevin equation for the extended Rayleigh model with an asymmetric bath
In this paper a one-dimensional model of two infinite gases separated by a
movable heavy piston is considered. The non-linear Langevin equation for the
motion of the piston is derived from first principles for the case when the
thermodynamic parameters and/or the molecular masses of gas particles on left
and right sides of the piston are different. Microscopic expressions involving
time correlation functions of the force between bath particles and the piston
are obtained for all parameters appearing in the non-linear Langevin equation.
It is demonstrated that the equation has stationary solutions corresponding to
directional fluctuation-induced drift in the absence of systematic forces. In
the case of ideal gases interacting with the piston via a quadratic repulsive
potential, the model is exactly solvable and explicit expressions for the
kinetic coefficients in the non-linear Langevin equation are derived. The
transient solution of the non-linear Langevin equation is analyzed
perturbatively and it is demonstrated that previously obtained results for
systems with the hard-wall interaction are recovered.Comment: 10 pages. To appear in Phys. Rev.
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
The spectrum of BPS branes on a noncompact Calabi-Yau
We begin the study of the spectrum of BPS branes and its variation on lines
of marginal stability on O_P^2(-3), a Calabi-Yau ALE space asymptotic to
C^3/Z_3. We show how to get the complete spectrum near the large volume limit
and near the orbifold point, and find a striking similarity between the
descriptions of holomorphic bundles and BPS branes in these two limits. We use
these results to develop a general picture of the spectrum. We also suggest a
generalization of some of the ideas to the quintic Calabi-Yau.Comment: harvmac, 45 pp. (v2: added references
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