227 research outputs found
Glycan-independent binding and internalization of human IgG to FCMR, its cognate cellular receptory
IgM is the first antibody to be produced in immune responses and plays an important role in the neutralization of bacteria and viruses. Human IgM is heavily glycosylated, featuring five N-linked glycan sites on the μ chain and one on the J-chain. Glycosylation of IgG is known to modulate the effector functions of Fcγ receptors. In contrast, little is known about the effect of glycosylation on IgM binding to the human Fcμ receptor (hFCMR). In this study, we identify the Cμ, omain of IgM as the target of hFCMR, and show that binding and internalization of IgM by hFCMR is glycan-independent. We generated a homology-based structure for hFCMR and used molecular dynamic simulations to show how this interaction with IgM may occur. Finally, we reveal an inhibitory function for IgM in the proliferation of T cells
GRDzhadzha: A code for evolving relativistic matter on analytic metric backgrounds
GRDzhadzha is an open-source code for relativistic simulations of matter
fields on curved spacetimes that admit an analytic description (e.g. stationary
black holes). It is based on the publicly available 3+1D numerical relativity
code GRChombo. Such a description is valid where the density of the matter is
small compared to the curvature scale of the spacetime, which is the case for
many physical scenarios - for example, dark matter environments. The approach
offers significant savings on memory and speed compared to running full
numerical relativity simulations, since the metric variables and their
derivatives are calculated analytically, and therefore are not evolved or
stored on the grid. This brief paper introduces the code and gives details of
some applications for which it has already been used.Comment: Submitted for review in the Journal of Open Source Software; Comments
welcome; The code can be found at https://github.com/GRChombo/GRDzhadzha.gi
Digital Signal Processing for Laser Printer Noise Source Detection and Identification
Presented here is the description of a software-based noise source detector that was developed to simplify the printing noise source identification process. The typical noise sources studied here were high frequency, stick-slip (squeaking) noises associated with rollers along the paper path. The detector was built by combining several digital signal processing procedures to first create a tone detector, and then to calculate the modulation spectrum of the tone. The latter is particularly important because it has been found that features appearing in the modulation spectrum can be directly associated with the rotational speed of various components in the printer; this allows the faulty part to be identified. By passing different printing noise samples through the detector, it was found that the detector accurately returned the acoustical characteristics of each noise sample, and then by matching those acoustical characteristics to the rotational speed of different parts, the detector was proven capable of providing robust and precise fault identification results
Simultaneous conversion of all cell wall components by an oleaginous fungus without chemi-physical pretreatment
Lignin utilization during biomass conversion has been a major challenge for lignocellulosic biofuel. In particular, the conversion of lignin along with carbohydrate for fungible fuels and chemicals will both improve the overall carbon efficiency and reduce the need for chemical pretreatments. However, few biomass-converting microorganisms have the capacity to degrade all cell wall components including lignin, cellulose, and hemicellulose. We hereby evaluated a unique oleaginous fungus strain, Cunninghamella echinulata FR3, for its capacity to degrade lignin during biomass conversion to lipid, and the potential to carry out consolidated fermentation without chemical pretreatment, especially when combined with sorghum (Sorghum bicolor) bmr mutants with reduced lignin content. The study clearly showed that lignin was consumed together with carbohydrate during biomass conversion for all sorghum samples, which indicates that this organism has the potential for biomass conversion without chemical pretreatment. Even though dilute acid pretreatment of biomass resulted in more weight loss during fungal fermentation than untreated biomass, the lipid yields were comparable for untreated bmr6/bmr12 double mutant and dilute acid-pretreated wild-type biomass samples. The mechanisms for lignin degradation in oleaginous fungi were further elucidated through transcriptomics and chemical analysis. The studies showed that in C. echinulata FR3, the Fenton reaction may play an important role in lignin degradation. This discovery is among the first to show that a mechanism for lignin degradation similar to those found in white and brown rot basidiomycetous fungi exists in an oleaginous fungus. This study suggests that oleaginous fungi such as C. echinulata FR3 can be employed for complete biomass utilization in a consolidated platform without chemical pretreatment or can be used to convert lignin waste into lipids
Retrieval study of cool, directly imaged exoplanet 51 Eri b
Retrieval methods are a powerful analysis technique for modelling
exoplanetary atmospheres by estimating the bulk physical and chemical
properties that combine in a forward model to best-fit an observed spectrum,
and they are increasingly being applied to observations of directly-imaged
exoplanets. We have adapted TauREx3, the Bayesian retrieval suite, for the
analysis of near-infrared spectrophotometry from directly-imaged gas giant
exoplanets and brown dwarfs. We demonstrate TauREx3's applicability to
sub-stellar atmospheres by presenting results for brown dwarf benchmark GJ 570D
which are consistent with previous retrieval studies, whilst also exhibiting
systematic biases associated with the presence of alkali lines. We also present
results for the cool exoplanet 51 Eri b, the first application of a free
chemistry retrieval analysis to this object, using spectroscopic observations
from GPI and SPHERE. While our retrieval analysis is able to explain
spectroscopic and photometric observations without employing cloud extinction,
we conclude this may be a result of employing a flexible temperature-pressure
profile which is able to mimic the presence of clouds. We present Bayesian
evidence for an ammonia detection with a 2.7 confidence, the first
indication of ammonia in an exoplanetary atmosphere. This is consistent with
this molecule being present in brown dwarfs of a similar spectral type. We
demonstrate the chemical similarities between 51 Eri b and GJ 570D in relation
to their retrieved molecular abundances. Finally, we show that overall
retrieval conclusions for 51 Eri b can vary when employing different spectral
data and modelling components, such as temperature-pressure and cloud
structures
Searching for non-Gaussianity in the VSA data
We have tested Very Small Array (VSA) observations of three regions of sky
for the presence of non-Gaussianity, using high-order cumulants, Minkowski
functionals, a wavelet-based test and a Bayesian joint power
spectrum/non-Gaussianity analysis. We find the data from two regions to be
consistent with Gaussianity. In the third region, we obtain a 96.7% detection
of non-Gaussianity using the wavelet test. We perform simulations to
characterise the tests, and conclude that this is consistent with expected
residual point source contamination. There is therefore no evidence that this
detection is of cosmological origin. Our simulations show that the tests would
be sensitive to any residual point sources above the data's source subtraction
level of 20 mJy. The tests are also sensitive to cosmic string networks at an
rms fluctuation level of (i.e. equivalent to the best-fit observed
value). They are not sensitive to string-induced fluctuations if an equal rms
of Gaussian CDM fluctuations is added, thereby reducing the fluctuations due to
the strings network to rms . We especially highlight the usefulness
of non-Gaussianity testing in eliminating systematic effects from our data.Comment: Minor corrections; accepted for publication to MNRA
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