7,131 research outputs found
Spatiotemporal characteristics of the walk-to-run and run-to-walk transition when gradually changing speed
Quantum engineering of atomic phase-shifts in optical clocks
Quantum engineering of time-separated Raman laser pulses in three-level
systems is presented to produce an ultra-narrow optical transition in bosonic
alkali-earth clocks free from light shifts and with a significantly reduced
sensitivity to laser parameter fluctuations. Based on a quantum artificial
complex-wave-function analytical model, and supported by a full density matrix
simulation including a possible residual effect of spontaneous emission from
the intermediate state, atomic phase-shifts associated to Ramsey and
Hyper-Ramsey two-photon spectroscopy in optical clocks are derived. Various
common-mode Raman frequency detunings are found where the frequency shifts from
off-resonant states are canceled, while strongly reducing their uncertainties
at the 10 level of accuracy.Comment: accepted for publication in PR
Adaptively time stepping the stochastic Landau-Lifshitz-Gilbert equation at nonzero temperature: implementation and validation in MuMax3
Thermal fluctuations play an increasingly important role in micromagnetic
research relevant for various biomedical and other technological applications.
Until now, it was deemed necessary to use a time stepping algorithm with a
fixed time step in order to perform micromagnetic simulations at nonzero
temperatures. However, Berkov and Gorn have shown that the drift term which
generally appears when solving stochastic differential equations can only
influence the length of the magnetization. This quantity is however fixed in
the case of the stochastic Landau-Lifshitz-Gilbert equation. In this paper, we
exploit this fact to straightforwardly extend existing high order solvers with
an adaptive time stepping algorithm. We implemented the presented methods in
the freely available GPU-accelerated micromagnetic software package MuMax3 and
used it to extensively validate the presented methods. Next to the advantage of
having control over the error tolerance, we report a twenty fold speedup
without a loss of accuracy, when using the presented methods as compared to the
hereto best practice of using Heun's solver with a small fixed time step.Comment: 9 pages, 9 figure
Onderzoekingen over de voedingswaarde van zeevisch: de chemische anatomie van <i>Merlangus vulgaris</i> (wijting) - Recherches sur la valeur alimentaire du poisson de mer: l'anatomie chimique de <i>Merlangus vulgaris</i> (Merlan)
Mitochondrial and chloroplast stress responses are modulated in distinct touch and chemical inhibition phases
Previous studies have identified a range of transcription factors that modulate retrograde regulation of mitochondrial and chloroplast functions in Arabidopsis (Arabidopsis thaliana). However, the relative importance of these regulators and whether they act downstream of separate or overlapping signaling cascades is still unclear. Here, we demonstrate that multiple stress-related signaling pathways, with distinct kinetic signatures, converge on overlapping gene sets involved in energy organelle function. The transcription factor ANAC017 is almost solely responsible for transcript induction of marker genes around 3 to 6 h after chemical inhibition of organelle function and is a key regulator of mitochondrial and specific types of chloroplast retrograde signaling. However, an independent and highly transient gene expression phase, initiated within 10 to 30 min after treatment, also targets energy organelle functions, and is related to touch and wounding responses. Metabolite analysis demonstrates that this early response is concurrent with rapid changes in tricarboxylic acid cycle intermediates and large changes in transcript abundance of genes encoding mitochondrial dicarboxylate carrier proteins. It was further demonstrated that transcription factors AtWRKY15 and AtWRKY40 have repressive regulatory roles in this touch-responsive gene expression. Together, our results show that several regulatory systems can independently affect energy organelle function in response to stress, providing different means to exert operational control
Investigating nystagmus in patients with traumatic brain injury: A systematic review (1996 - 2016)
Background. Traumatic brain injury (TBI) is a health and socioeconomic concern worldwide. In patients with TBI, post-traumatic balance problems are often the result of damage to the vestibular system. Nystagmus is common in these patients, and can provide insight into the damage that has resulted from the trauma.Objective. To present a systematic overview of published literature regarding nystagmus in patients with TBI.Methods. Nine databases and platforms were searched during October 2016 for articles published between 1996 and 2016. Studies of any research design and published in English that focused on nystagmus in patients with TBI were considered for inclusion. A total of 110Â articles were screened once duplicates had been removed, and 29 full-text articles were assessed. Eleven articles were included in the quality appraisal phase (using the McMaster tool), after which 10 articles were included in this review.Results. This review describes nystagmus in 713 patients, and all articles reviewed described the type of assessment method that was used. However, the results lacked comprehensive data regarding the assessment, measurement and description of nystagmus in TBI patients, or the possible link and relationship between nystagmus and TBI.Conclusions. This systematic review indicated that: (i) there is a growing body of evidence that benign paroxysmal positional vertigo should be considered during the medical examination of all patients suffering from head trauma; (ii) all patients with TBI should undergo visual (eye movement) and vestibular examination; and (iii) future studies should include quantitative measurements of eye movements and nystagmus.
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