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Sleep disturbance at pre-deployment is a significant predictor of post-deployment re-experiencing symptoms.
Background: Insomnia is common in service members and associated with many mental and physical health problems. Recently, longitudinal data have been used to assess the impact of disturbed sleep on mental health outcomes. These studies have consistently shown relationships between sleep disturbance and development of mental illness. Objective: The present study examined the longitudinal relationship between sleep disturbance and PTSD symptomatology in a cohort of Marines and Navy Corpsmen deployed to Iraq and Afghanistan (n = 2,404) assessed prior to deployment, as well as at -3 and 6 months post-deployment. Additionally, we aimed to investigate the extent to which these relationships are moderated by combat-stress severity, and to what extent these findings are replicated in a second, separate cohort of Marines and Navy corpsmen (n = 938) assessed with identical measures prior to deployment and within 3 months of return. Method: The present study employed latent variable path models to examine the relationships between pre-deployment sleep disturbance and post-deployment re-experiencing symptoms. Initial cross-lagged path models were conducted on discovery and replication samples to validate the hypothesized predictive relationships. Follow up moderation path models were then conducted to include the effect of combat-stress severity on these relationships. Results: Initial cross-lagged models supported a significant relationship between pre-deployment sleep disturbance and future re-experiencing PTSD symptoms at all time points. Initial moderation models showed a small moderator effect of combat-stress severity, though the main predictive relationship between pre-deployment sleep disturbance and PTSD symptoms remained significant. The moderator effect was not significant in the replication sample. Conclusions: The results of this study support pre-deployment sleep disturbance as a risk factor for development of post-deployment PTSD symptoms. Interventions aimed at normalizing sleep may be important in preventive measures for PTSD
A Hybrid Lagrangian Variation Method for Bose-Einstein Condensates in Optical Lattices
Solving the Gross--Pitaevskii (GP) equation describing a Bose--Einstein
condensate (BEC) immersed in an optical lattice potential can be a numerically
demanding task. We present a variational technique for providing fast, accurate
solutions of the GP equation for systems where the external potential exhibits
rapid varation along one spatial direction. Examples of such systems include a
BEC subjected to a one--dimensional optical lattice or a Bragg pulse. This
variational method is a hybrid form of the Lagrangian Variational Method for
the GP equation in which a hybrid trial wavefunction assumes a gaussian form in
two coordinates while being totally unspecified in the third coordinate. The
resulting equations of motion consist of a quasi--one--dimensional GP equation
coupled to ordinary differential equations for the widths of the transverse
gaussians. We use this method to investigate how an optical lattice can be used
to move a condensate non--adiabatically.Comment: 16 pages and 1 figur
A Hybrid Lagrangian Variational Method for Bose–Einstein Condensates in Optical Lattices
Solving the Gross–Pitaevskii (GP) equation describing a Bose–Einstein condensate (BEC) immersed in an optical lattice potential can be a numerically demanding task. We present a variational technique for providing fast, accurate solutions of the GP equation for systems where the external potential exhibits rapid variation along one spatial direction. Examples of such systems include a BEC subjected to a one-dimensional optical lattice or a Bragg pulse. This variational method is a hybrid form of the Lagrangian variational method for the GP equation in which a hybrid trial wavefunction assumes a Gaussian form in two coordinates while being totally unspecified in the third coordinate. The resulting equations of motion consist of a quasi-one-dimensional GP equation coupled to ordinary differential equations for the widths of the transverse Gaussians. We use this method to investigate how an optical lattice can be used to move a condensate non-adiabatically
Front propagation into unstable and metastable states in Smectic C* liquid crystals: linear and nonlinear marginal stability analysis
We discuss the front propagation in ferroelectric chiral smectics (SmC*)
subjected to electric and magnetic fields applied parallel to smectic layers.
The reversal of the electric field induces the motion of domain walls or fronts
that propagate into either an unstable or a metastable state. In both regimes,
the front velocity is calculated exactly. Depending on the field, the speed of
a front propagating into the unstable state is given either by the so-called
linear marginal stability velocity or by the nonlinear marginal stability
expression. The cross-over between these two regimes can be tuned by a magnetic
field. The influence of initial conditions on the velocity selection problem
can also be studied in such experiments. SmC therefore offers a unique
opportunity to study different aspects of front propagation in an experimental
system
The Radio Sky at Meter Wavelengths: m-Mode Analysis Imaging with the Owens Valley Long Wavelength Array
A host of new low-frequency radio telescopes seek to measure the 21-cm
transition of neutral hydrogen from the early universe. These telescopes have
the potential to directly probe star and galaxy formation at redshifts , but are limited by the dynamic range they can achieve
against foreground sources of low-frequency radio emission. Consequently, there
is a growing demand for modern, high-fidelity maps of the sky at frequencies
below 200 MHz for use in foreground modeling and removal. We describe a new
widefield imaging technique for drift-scanning interferometers,
Tikhonov-regularized -mode analysis imaging. This technique constructs
images of the entire sky in a single synthesis imaging step with exact
treatment of widefield effects. We describe how the CLEAN algorithm can be
adapted to deconvolve maps generated by -mode analysis imaging. We
demonstrate Tikhonov-regularized -mode analysis imaging using the Owens
Valley Long Wavelength Array (OVRO-LWA) by generating 8 new maps of the sky
north of with 15 arcmin angular resolution, at frequencies
evenly spaced between 36.528 MHz and 73.152 MHz, and 800 mJy/beam thermal
noise. These maps are a 10-fold improvement in angular resolution over existing
full-sky maps at comparable frequencies, which have angular resolutions . Each map is constructed exclusively from interferometric observations
and does not represent the globally averaged sky brightness. Future
improvements will incorporate total power radiometry, improved thermal noise,
and improved angular resolution -- due to the planned expansion of the OVRO-LWA
to 2.6 km baselines. These maps serve as a first step on the path to the use of
more sophisticated foreground filters in 21-cm cosmology incorporating the
measured angular and frequency structure of all foreground contaminants.Comment: 27 pages, 18 figure
Non-linear Multi-level Dynamics of a SQUID Ring-resonator System in the Hysteretic Regime
We consider the dynamical behavior of a strongly hysteretic SQUID ring coupled to a radio frequency resonator. By experiment we show that this system can display novel multiple level structures in its rf voltage-current characteristics which are solutions of the nonlinear equations of motion describing the system
Sustainability appraisal: Jack of all trades, master of none?
Sustainable development is a commonly quoted goal for decision making and supports a large number of other discourses. Sustainability appraisal has a stated goal of supporting decision making for sustainable development. We suggest that the inherent flexibility of sustainability appraisal facilitates outcomes that often do not adhere to the three goals enshrined in most definitions of sustainable development: economic growth, environmental protection and enhancement, and the wellbeing of the human population. Current practice is for sustainable development to be disenfranchised through the interpretation of sustainability, whereby the best alternative is good enough even when unsustainable. Practitioners must carefully and transparently review the frameworks applied during sustainability appraisal to ensure that outcomes will meet the three goals, rather than focusing on a discourse that emphasises one or more goals at the expense of the other(s)
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