10,383 research outputs found
Stellar wind-magnetosphere interaction at exoplanets: computations of auroral radio powers
We present calculations of the auroral radio powers expected from exoplanets
with magnetospheres driven by an Earth-like magnetospheric interaction with the
solar wind. Specifically, we compute the twin cell-vortical ionospheric flows,
currents, and resulting radio powers resulting from a Dungey cycle process
driven by dayside and nightside magnetic reconnection, as a function of
planetary orbital distance and magnetic field strength. We include saturation
of the magnetospheric convection, as observed at the terrestrial magnetosphere,
and we present power law approximations for the convection potentials, radio
powers and spectral flux densities. We specifically consider a solar-age system
and a young (1 Gyr) system. We show that the radio power increases with
magnetic field strength for magnetospheres with saturated convection potential,
and broadly decreases with increasing orbital distance. We show that the
magnetospheric convection at hot Jupiters will be saturated, and thus unable to
dissipate the full available incident Poynting flux, such that the magnetic
Radiometric Bode's Law (RBL) presents a substantial overestimation of the radio
powers for hot Jupiters. Our radio powers for hot Jupiters are 5-1300 TW
for hot Jupiters with field strengths of 0.1-10 orbiting a Sun-like star,
while we find that competing effects yield essentially identical powers for hot
Jupiters orbiting a young Sun-like star. However, in particular for planets
with weaker magnetic fields our powers are higher at larger orbital distances
than given by the RBL, and there are many configurations of planet that are
expected to be detectable using SKA.Comment: Accepted for publication in Mon. Not. R. Astron. So
NAIP/NLRC4 inflammasome activation in MRP8+ cells is sufficient to cause systemic inflammatory disease.
Inflammasomes are cytosolic multiprotein complexes that initiate protective immunity in response to infection, and can also drive auto-inflammatory diseases, but the cell types and signalling pathways that cause these diseases remain poorly understood. Inflammasomes are broadly expressed in haematopoietic and non-haematopoietic cells and can trigger numerous downstream responses including production of IL-1β, IL-18, eicosanoids and pyroptotic cell death. Here we show a mouse model with endogenous NLRC4 inflammasome activation in Lysozyme2 + cells (monocytes, macrophages and neutrophils) in vivo exhibits a severe systemic inflammatory disease, reminiscent of human patients that carry mutant auto-active NLRC4 alleles. Interestingly, specific NLRC4 activation in Mrp8 + cells (primarily neutrophil lineage) is sufficient to cause severe inflammatory disease. Disease is ameliorated on an Asc -/- background, and can be suppressed by injections of anti-IL-1 receptor antibody. Our results provide insight into the mechanisms by which NLRC4 inflammasome activation mediates auto-inflammatory disease in vivo
A guideline for heavy ion radiation testing for Single Event Upset (SEU)
A guideline for heavy ion radiation testing for single event upset was prepared to assist new experimenters in preparing and directing tests. How to estimate parts vulnerability and select an irradiation facility is described. A broad brush description of JPL equipment is given, certain necessary pre-test procedures are outlined and the roles and testing guidelines for on-site test personnel are indicated. Detailed descriptions of equipment needed to interface with JPL test crew and equipment are not provided, nor does it meet the more generalized and broader requirements of a MIL-STD document. A detailed equipment description is available upon request, and a MIL-STD document is in the early stages of preparation
Dynamic filtering of static dipoles in magnetoencephalography
We consider the problem of estimating neural activity from measurements
of the magnetic fields recorded by magnetoencephalography. We exploit
the temporal structure of the problem and model the neural current as a
collection of evolving current dipoles, which appear and disappear, but whose
locations are constant throughout their lifetime. This fully reflects the physiological
interpretation of the model.
In order to conduct inference under this proposed model, it was necessary
to develop an algorithm based around state-of-the-art sequential Monte
Carlo methods employing carefully designed importance distributions. Previous
work employed a bootstrap filter and an artificial dynamic structure
where dipoles performed a random walk in space, yielding nonphysical artefacts
in the reconstructions; such artefacts are not observed when using the
proposed model. The algorithm is validated with simulated data, in which
it provided an average localisation error which is approximately half that of
the bootstrap filter. An application to complex real data derived from a somatosensory
experiment is presented. Assessment of model fit via marginal
likelihood showed a clear preference for the proposed model and the associated
reconstructions show better localisation
Weak Hopf algebras corresponding to Cartan matrices
We replace the group of group-like elements of the quantized enveloping
algebra of a finite dimensional semisimple Lie algebra
by some regular monoid and get the weak Hopf algebra
. It is a new subclass of weak Hopf algebras
but not Hopf algebras. Then we devote to constructing a basis of
and determine the group of weak Hopf algebra
automorphisms of when is not a root of
unity.Comment: 21 page
Cluster Mass Inference Method via Random Field Theory
Cluster extent and voxel intensity are two widely used statistics in neuroimaging inference. Cluster extent is sensitive to spatially extended signals while voxel intensity is better for intense but focal signals. In order to leverage strength from both statistics, several nonparametric permutation methods have been proposed to combine the two methods. Simulation studies have shown that of the different cluster permutation methods, the cluster mass statistic is generally the best. However, to date, there is no parametric cluster mass inference available. In this paper, we propose a cluster mass inference method based on random field theory (RFT). We develop this method for Gaussian images, extend it to Student’s t-statistic images and investigate its statistical properties via simulation studies and real data. Simulation results show that the method is valid under the null hypothesis and demonstrate that it can be more powerful than the cluster extent inference method. Further, analyses with a single-subject and a group fMRI dataset demonstrate better power than traditional cluster size inference, and good accuracy relative to a gold-standard permutation test
Bayesian log-Gaussian Cox process regression: applications to meta-analysis of neuroimaging working memory studies
Working memory (WM) was one of the first cognitive processes studied with
functional magnetic resonance imaging. With now over 20 years of studies on WM,
each study with tiny sample sizes, there is a need for meta-analysis to
identify the brain regions that are consistently activated by WM tasks, and to
understand the interstudy variation in those activations. However, current
methods in the field cannot fully account for the spatial nature of
neuroimaging meta-analysis data or the heterogeneity observed among WM studies.
In this work, we propose a fully Bayesian random-effects metaregression model
based on log-Gaussian Cox processes, which can be used for meta-analysis of
neuroimaging studies. An efficient Markov chain Monte Carlo scheme for
posterior simulations is presented which makes use of some recent advances in
parallel computing using graphics processing units. Application of the proposed
model to a real data set provides valuable insights regarding the function of
the WM
Radiation effects on silicon solar cells Final report, Dec. 1, 1961 - Dec. 31, 1962
Displacement defects in silicon solar cells by high energy electron irradiation using electron spin resonance, galvanometric, excess carrier lifetime, and infrared absorption measurement
Microdosing psychedelics: More questions than answers? An overview and suggestions for future research
Background: In the past few years, the issue of \u2018microdosing\u2019 psychedelics has been openly discussed in the public arena where claims have been made about their positive effect on mood state and cognitive processes such as concentration. However, there are very few scientific studies that have specifically addressed this issue, and there is no agreed scientific consensus on what microdosing is. Aim: This critique paper is designed to address questions that need to be answered by future scientific studies and to offer guidelines for these studies. Approach: Owing to its proximity for a possible approval in clinical use and short-lasting pharmacokinetics, our focus is predominantly on psilocybin. Psilocybin is allegedly, next to lysergic acid diethylamide (LSD), one of the two most frequently used psychedelics to microdose. Where relevant and available, data for other psychedelic drugs are also mentioned. Conclusion: It is concluded that while most anecdotal reports focus on the positive experiences with microdosing, future research should also focus on potential risks of (multiple) administrations of a psychedelic in low doses. To that end, (pre)clinical studies including biological (e.g. heart rate, receptor turnover and occupancy) as well as cognitive (e.g. memory, attention) parameters have to be conducted and will shed light on the potential negative consequences microdosing could have
NAIP proteins are required for cytosolic detection of specific bacterial ligands in vivo.
NLRs (nucleotide-binding domain [NBD] leucine-rich repeat [LRR]-containing proteins) exhibit diverse functions in innate and adaptive immunity. NAIPs (NLR family, apoptosis inhibitory proteins) are NLRs that appear to function as cytosolic immunoreceptors for specific bacterial proteins, including flagellin and the inner rod and needle proteins of bacterial type III secretion systems (T3SSs). Despite strong biochemical evidence implicating NAIPs in specific detection of bacterial ligands, genetic evidence has been lacking. Here we report the use of CRISPR/Cas9 to generate Naip1(-/-) and Naip2(-/-) mice, as well as Naip1-6(Δ/Δ) mice lacking all functional Naip genes. By challenging Naip1(-/-) or Naip2(-/-) mice with specific bacterial ligands in vivo, we demonstrate that Naip1 is uniquely required to detect T3SS needle protein and Naip2 is uniquely required to detect T3SS inner rod protein, but neither Naip1 nor Naip2 is required for detection of flagellin. Previously generated Naip5(-/-) mice retain some residual responsiveness to flagellin in vivo, whereas Naip1-6(Δ/Δ) mice fail to respond to cytosolic flagellin, consistent with previous biochemical data implicating NAIP6 in flagellin detection. Our results provide genetic evidence that specific NAIP proteins function to detect specific bacterial proteins in vivo
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