Abstract
Planet formation is thought to occur in discs around young stars by the aggregation of small dust grains into much larger objects. The growth from grains to pebbles and from planetesimals to ...planets is now fairly well understood. The intermediate stage has however been found to be hindered by the radial-drift and fragmentation barriers. We identify a powerful mechanism in which dust overcomes both barriers. Its key ingredients are (i) backreaction from the dust on to the gas, (ii) grain growth and fragmentation and (iii) large-scale gradients. The pile-up of growing and fragmenting grains modifies the gas structure on large scales and triggers the formation of pressure maxima, in which particles are trapped. We show that these self-induced dust traps are robust: they develop for a wide range of disc structures, fragmentation thresholds and initial dust-to-gas ratios. They are favoured locations for pebbles to grow into planetesimals, thus opening new paths towards the formation of planets.
It is well known that sexual selection can target reproductive traits during successive pre‐ and post‐mating episodes of selection. A key focus of recent studies has been to understand and quantify ...how these episodes of sexual selection interact to determine overall variance in reproductive success. In this article, we review empirical developments in this field but also highlight the considerable variability in patterns of pre‐ and post‐mating sexual selection, attributable to variation in patterns of resource acquisition and allocation, ecological and social factors, genotype‐by‐environment interaction and possible methodological factors that might obscure such patterns. Our aim is to highlight how (co)variances in pre‐ and post‐mating sexually selected traits can be sensitive to changes in a range of ecological and environmental variables. We argue that failure to capture this variation when quantifying the opportunity for sexual selection may lead to erroneous conclusions about the strength, direction or form of sexual selection operating on pre‐ and post‐mating traits. Overall, we advocate for approaches that combine measures of pre‐ and post‐mating selection across contrasting environmental or ecological gradients to better understand the dynamics of sexual selection in polyandrous species. We also discuss some directions for future research in this area.
Numerical schemes to approximate the Cahn–Hilliard equation have been widely studied in recent times due to its connection with many physically motivated problems. In this work we propose two type of ...linear schemes based on different ways to approximate the double-well potential term. The first idea developed in the paper allows us to design a linear numerical scheme which is optimal from the numerical dissipation point of view meanwhile the second one allows us to design unconditionally energy-stable linear schemes (for a modified energy). We present first and second order in time linear schemes to approximate the CH problem, detailing their advantages over other linear schemes that have been previously introduced in the literature. Furthermore, we compare all the schemes through several computational experiments.
We study Primordial Black Holes (PBHs) as sources of massive neutrinos via Hawking radiation. Under the hypothesis that black holes emit neutrino mass eigenstates, we describe quantitatively how the ...PBH evolution and lifetime is affected by the mass and fermionic—Dirac or Majorana—nature of neutrinos. In the case of Dirac neutrinos, PBHs radiate right-handed and left-handed neutrinos in equal amounts, thus possibly increasing the effective number of neutrino species, Neff. Assuming an initially monochromatic PBH mass spectrum, with the initial mass Mi related to the particle horizon mass, and considering the current constraint on Neff, we derive a bound on the initial PBH fraction β′ in the interval 4.3×107g≲Mi≲109 g. Future measurements of Neff may be able to constraint the initial fraction for black hole masses as low as 1 g. If an excess in Neff is found, PBHs with Dirac neutrinos could provide a minimal explanation of it. For example, for 107g≲Mi≲109 g and β′≳10−13, an excess radiation at the level of 0.2≲ΔNeff≲0.37 is produced, which can alleviate the tension of the Hubble parameter measurements. Finally, we obtain the diffuse flux of right-helical neutrinos from PBHs at the Earth, and show that their detection in a PTOLEMY-like detector (using neutrino capture on tritium) would be difficult.
Stromal-derived follicular dendritic cells (FDCs) are a major reservoir for antigen that are essential for formation of germinal centers, the site where memory and effector B cells differentiate. A ...long-standing question is how FDCs retain antigen in its native form for extended periods and how they display it to specific B cells. Here we found that FDCs acquired complement-coated immune complexes (ICs) from noncognate B cells via complement receptors 1 and 2 (CD35 and CD21, respectively) and rapidly internalized them by an actin-dependent pathway. ICs were retained intact within a nondegradative cycling compartment and were displayed periodically on the cell surface where they were accessible to antigen-specific B cells. This would explain how antigens are protected from damage and retained over long periods of time, while remaining accessible for B cells.
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•Visualizing direct immune complex transfer from noncognate B cells to FDCs in vivo•Uptake of immune complexes from noncognate B cells by FDCs is actin dependent•Immune complexes cycling to the FDC surface are displayed for B cell acquisition•In vivo, FDCs retain immune complexes in a cycling compartment for at least 16 days
Abstract
The Allele Frequency Net Database (AFND, www.allelefrequencies.net) provides the scientific community with a freely available repository for the storage of frequency data (alleles, genes, ...haplotypes and genotypes) related to human leukocyte antigens (HLA), killer-cell immunoglobulin-like receptors (KIR), major histocompatibility complex Class I chain related genes (MIC) and a number of cytokine gene polymorphisms in worldwide populations. In the last five years, AFND has become more popular in terms of clinical and scientific usage, with a recent increase in genotyping data as a necessary component of Short Population Report article submissions to another scientific journal. In addition, we have developed a user-friendly desktop application for HLA and KIR genotype/population data submissions. We have also focused on classification of existing and new data into ‘gold–silver–bronze’ criteria, allowing users to filter and query depending on their needs. Moreover, we have also continued to expand other features, for example focussed on HLA associations with adverse drug reactions. At present, AFND contains >1600 populations from >10 million healthy individuals, making AFND a valuable resource for the analysis of some of the most polymorphic regions in the human genome.
Surveying threatened and invasive species to obtain accurate population estimates is an important but challenging task that requires a considerable investment in time and resources. Estimates using ...existing ground-based monitoring techniques, such as camera traps and surveys performed on foot, are known to be resource intensive, potentially inaccurate and imprecise, and difficult to validate. Recent developments in unmanned aerial vehicles (UAV), artificial intelligence and miniaturized thermal imaging systems represent a new opportunity for wildlife experts to inexpensively survey relatively large areas. The system presented in this paper includes thermal image acquisition as well as a video processing pipeline to perform object detection, classification and tracking of wildlife in forest or open areas. The system is tested on thermal video data from ground based and test flight footage, and is found to be able to detect all the target wildlife located in the surveyed area. The system is flexible in that the user can readily define the types of objects to classify and the object characteristics that should be considered during classification.
A
bstract
The detection of coherent neutrino-nucleus scattering by the COHERENT collaboration has set on quantitative grounds the existence of an irreducible neutrino background in direct detection ...searches of Weakly Interacting Massive Dark Matter candidates. This background leads to an ultimate discovery limit for these experiments: a minimum Dark Matter interaction cross section below which events produced by the coherent neutrino scattering will mimic the Dark Matter signal, the so-called
neutrino floor
. In this work we study the modification of such neutrino floor induced by non-standard neutrino interactions within their presently allowed values by the global analysis of oscillation and COHERENT data. By using the full likelihood information of such global analysis we consistently account for the correlated effects of non-standard neutrino interactions both in the neutrino propagation in matter and in its interaction in the detector. We quantify their impact on the neutrino floor for five future experiments: DARWIN (Xe), ARGO (Ar), Super-CDMS HV (Ge and Si) and CRESST phase III (CaWO
4
). Quantitatively, we find that non-standard neutrino interactions allowed at the 3
σ
level can result in an increase of the neutrino floor of up to a factor ∼ 5 with respect to the Standard Model expectations and impact the expected sensitivities of the ARGO, CRESST phase III and DARWIN experiments.
Objective
To evaluate the effectiveness of virtual reality as a distraction technique in the management of acute pain and anxiety during outpatient hysteroscopy.
Design
Parallel group, prospective ...randomised controlled trial.
Setting
UK University Hospital.
Methods
Forty consenting, eligible women were randomised to virtual reality intervention (immersive video content as a distraction method) or standard care during outpatient hysteroscopy from August to October 2018.
Main outcome measures
Pain and anxiety outcomes were measured as a numeric rating score (scale 0–10).
Results
Compared with standard care, women with virtual reality intervention experienced less average pain (score 6.0 versus 3.7, mean difference 2.3, 95% CI 0.61–3.99, P = 0.009) and anxiety (score 5.45 versus 3.3, mean difference 2.15, 95% CI 0.38–3.92, P = 0.02).
Conclusion
Virtual reality was effective in reducing pain and anxiety during outpatient hysteroscopy in a mixed‐methods randomised control trial. Its wide potential role in ambulatory gynaecological procedures needs further evaluation.
Tweetable
Virtual reality can be used as a part of a multimodal strategy to reduce acute pain and anxiety in patients undergoing outpatient hysteroscopy.
Tweetable
Virtual reality can be used as a part of a multimodal strategy to reduce acute pain and anxiety in patients undergoing outpatient hysteroscopy.
Albumins, in the form of nanoparticles, are increasingly used as drug carriers in the medical field, and the size effect of these nanomaterials is of major importance since it may affect their ...bioavailability and the in vivo behaviour after intravenous injection. This research provides a comprehensive study on the preparation of BSA nanoparticles, based on a simple coacervation method, with suitable size, size distribution, and surface charge for drug-delivery applications. Numerous experimental variables were examined in order to characterize their impact on nanoparticle size, distribution, electrophoretic mobility, and yield. Particle size was controlled by adjusting self-assembly phenomena of the protein molecules, which was affected by preparation conditions including BSA content, pH, and ionic strength (a parameter that strongly influences nanoparticle formation but surprisingly has not been previously studied in detail). Small particles with a narrow size distribution were obtained under experimental conditions where the repulsion between BSA molecules was high, i.e. at pH values far from the isoelectric point of the protein and low salt concentration. Changes in temperature, volume, and rate of addition of the dehydrating agent (ethanol) also affect nanoparticle characteristics, as they influence the nucleation rate and particle growth. The effect of these experimental conditions on the quantity of protein still dissolved in the aqueous phase after desolvation (i.e. the yield of BSA nanoparticles) was also studied. Nanoparticles surface charge was modulated with the extension of cross-linking. Finally, long-term colloidal stability of samples was evaluated after 2 months of storage.
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