1,245 research outputs found
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The circulatory impact of dust from dust profile assimilation
We present results from a reanalysis of temperatures, dust columns and dust vertical profiles focussing on the assimilation, distribution and transport of dust in the martian atmosphere. The assimilation of dust vertical information in particular is a valuable technique which has been shown to be of vital importance to a successful assimilation of the martian atmosphere, with the vertical representation of the dust distribution having a critical effect on assimilation results generally.
Atmospheric dust is a key driver of the martian circulation. Dust-induced heating and cooling is a potential feedback mechanism for dust lifting, for example, and can modify the circulation to either enhance or suppress dust storm activity. Accurately representing its complex spatial and temporal distribution is therefore crucial for understanding Marsâ atmospheric dynamics and transport
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Planetary wave reanalysis using satellite data
A key motivation to use data assimilation for plane-tary science is in order to recover information about day-to-day atmospheric variability, or âweatherâ. Whilst there is no immediate need for a regular weather forecast in most planetary science, data assimilation offers the prospect of a systematic rea-nalysis of past and present spacecraft data. This is especially valuable when, as is often the case, a planet is being observed from only one or two orbital platforms at any one time and synoptic-scale weather system may translate and change signifi-cantly between satellite passes. Observations are often sparse and incomplete. This leads to problems of aliasing and potential ambiguity in a convention-al data analysis
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Investigating the Role of Advection Processes in Improved Martian Dust Assimilation Techniques for ExoMars
Mineral dust is a key component in the atmosphere of Mars, and understanding its properties and behaviour is therefore key for planning and performing future activity on the planet. Data assimilation is a technique for combining observations with an atmospheric model, in this case the LMD-UK Mars General Circulation Model (MGCM). We describe its benefits and previous work in Martian data assimilation, and demonstrate its utility by examining a regional dust event in Mars Year 26 using Thermal Emission Spectrometer (TES) dust optical depth observations.
We set out aims to improve upon current dust assimilation techniques, specifically regarding the advection of dust within the assimilation, in preparation for forthcoming high-resolution dust observations from the ExoMars Trace Gas Orbiter (TGO) and its NOMAD spectrometer
Bright X-ray radiation from plasma bubbles in an evolving laser wakefield accelerator
We show that the properties of the electron beam and bright x-rays produced
by a laser wakefield accelerator can be predicted if the distance over which
the laser self-focuses and compresses prior to self-injection is taken into
account. A model based on oscillations of the beam inside a plasma bubble shows
that performance is optimised when the plasma length is matched to the laser
depletion length. With a 200~TW laser pulse this results in an x-ray beam with
median photon energy of \unit[20]{keV}, photons above
\unit[1]{keV} per shot and a peak brightness of \unit[3 \times
10^{22}]{photons~s^{-1}mrad^{-2}mm^{-2} (0.1\% BW)^{-1}}.Comment: 5 pages, 4 figure
Measuring fast electron spectra and laser absorption in relativistic laser-solid interactions using differential bremsstrahlung photon detectors
A photon detector suitable for the measurement of bremsstrahlung spectra
generated in relativistically-intense laser-solid interactions is described.
The Monte Carlo techniques used to back-out the fast electron spectrum and
laser energy absorbed into fast electrons are detailed. A
relativistically-intense laser-solid experiment using frequency doubled laser
light is used to demonstrate the effective operation of the detector. The
experimental data was interpreted using the 3-spatial-dimension Monte Carlo
code MCNPX (Pelowitz 2008), and the fast electron temperature found to be 125
keV
Effects of Yoga on Thalamic Gamma-Aminobutyric Acid, Mood and Depression: Analysis of Two Randomized Controlled Trials
Objective: The Vagal-Gamma-Aminobutyric Acid (GABA) theory proposes that some yoga postures and breathing practices exert their effects through stimulation of vagal nerves (parasympathetic system) with associated brain GABA increases. To evaluate this theory, we compared results from a 12-week randomized controlled trial (RCT) of yoga in participants with Major Depressive Disorder (MDD) with those of a similar RCT in healthy control participants (HC).
Methods: In an RCT, magnetic resonance spectroscopy (MRS) and mood measures were acquired in subjects with MDD (n=15) prior to and following a 12-week yoga intervention. The same measures were obtained in the HC (n=17) group. In both studies, thalamic GABA/Creatine was obtained using MEGAPRESS at 4 Telsa at baseline (Scan-1), post-intervention (Scan-2), and immediately following a yoga session (Scan-3). Clinical scales were completed prior to each scan.
Results: The MDD-group had significantly lower GABA compared to the HC at baseline (Scan-1, p=0.001), but not after 12 weeks of yoga, either before (Scan-2, p=0.12) or after a yoga session (Scan-3, p=0.20). Depressive symptoms decreased significantly in the MDD-group (p=0.0001), and anxiety improved in both groups.
Conclusion: After a 12-week yoga intervention, MDD-group mood and anxiety measures improved with scores equivalent to those of non-depressed individuals. This study provides the first evidence of brain GABA increases associated with specific yoga postures and breathing practices in MDD. These results suggest potential benefits of specific yoga postures and breathing practices as monotherapy or augmentation to other treatments to reduce anxiety and depression in MDD
Testimony at court: a randomised controlled trial investigating the art and science of persuading witnesses and victims to attend trial
The presence of civilian witnesses and victims in court is central to the effective operation of the criminal justice system. However, there is evidence of significant non-attendance which can result in ineffective and cracked trials. To address this, West Midlands Police Witness Care Unit and the Behavioural Insights Team designed an intervention using behavioural insight principles consisting of (1) a new conversation guide for Witness Care Officers (WCOs); (2) a redesigned âWarning Letterâ confirming details of the proceedings; and (3) a new reminder call and SMS. The impact of the new approach was evaluated through a randomised controlled trial in which 36 WCOs were randomly assigned to either âbusiness as usualâ (control) or treatment. The evaluation used an intention-to-treat design with implementation guided and encouraged at several points. Subgroup analysis was undertaken to explore whether differential effects were seen for domestic violence cases or between those that were victims and witnesses. Results indicated that the treatment approach was directionally positive in all cases, but that the increase in attendance was not statistically significant. This is in line with findings of other similar research in this area
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