Fast radio bursts (FRBs) are millisecond-duration radio transients
of unknown origin. Two possible mechanisms that could generate extremely coherent emission from FRBs invoke neutron star ...magnetospheres
or relativistic shocks far from the central energy source
. Detailed polarization observations may help us to understand the emission mechanism. However, the available FRB polarization data have been perplexing, because they show a host of polarimetric properties, including either a constant polarization angle during each burst for some repeaters
or variable polarization angles in some other apparently one-off events
. Here we report observations of 15 bursts from FRB 180301 and find various polarization angle swings in seven of them. The diversity of the polarization angle features of these bursts is consistent with a magnetospheric origin of the radio emission, and disfavours the radiation models invoking relativistic shocks.
To better understand and quantify soiling rates on solar panels, we are investigating the adhesion mechanisms between dust particles and solar glass. In this work, we report on two of the fundamental ...adhesion mechanisms: van der Waals and capillary adhesion forces. The adhesion was determined using force versus distance (F-z) measurements performed with an atomic force microscope (AFM). To emulate dust interacting with the front surface of a solar panel, we measured how oxidized AFM tips, SiO2 glass spheres, and real dust particles adhered to actual solar glass. The van der Waals forces were evaluated by measurements performed with zero relative humidity in a glove box, and the capillary forces were measured in a stable environment created inside the AFM enclosure with relative humidity values ranging from 18% to 80%. To simulate topographic features of the solar panels caused by factors such as cleaning and abrasion, we induced different degrees of surface roughness in the solar glass. We were able to 1) identify and quantify both the van der Waals and capillary forces, 2) establish the effects of surface roughness, relative humidity, and particle size on the adhesion mechanisms, and 3) compare adhesion forces between well-controlled particles (AFM tips and glass spheres) and real dust particles.
•Determination of the initial soiling mechanisms on solar glass: van der Waals, capillary forces.•Measurements using simulated dust particles, AFM tips and glass spheres, and real dust particles.•Study of the influence of surface roughness, humidity, particle size on the soiling mechanisms.•Results explain report that hurricane-speed wind is not able to remove small particles from glass.•Theoretical model provides good agreement with the van der Waals interaction.
Social networks have recently been widely explored in many fields; these networks are composed of a set of autonomous social actors and the interaction relations among them. Multiagent computing has ...already been widely envisioned to be a powerful paradigm for modeling autonomous multientity systems; therefore, it is promising to connect the research on social networks and multiagent systems. In general, there are three views for research on social networks: the structure-oriented view, in which only the network structure characteristics among actors are considered, the actor-oriented view, in which only the behavior characteristics of actors are considered, and the actor-structure crossing view, in which both actors and network structures are considered and their crossing effects are explored. This survey paper mainly concerns studies on social networks that have the last two views and discusses the relationship between social networks and multiagent systems. Because coordination is critical for both multiagent systems and social networks, this paper classifies studies on social networks that are based on the coordination mechanisms among the actors in the social networks. By referring to typical types of coordination situations in multiagent systems, social networks in previous studies can be classified into three classes: cooperative social networks, noncooperative social networks, and multiple social networks; for each class, this paper reviews the existing studies and discusses the challenge issues and possible future research directions. From this survey, we find that social networks can be understood well via a multiagent coordination perspective and also that many multiagent coordination techniques can be cogently applied in research on social networks. Moreover, this paper discusses the advantages and disadvantages of the multiagent coordination perspective by comparing with other perspectives on studying social networks.
Evasion of immune system is a hallmark of cancer, which enables cancer cells to escape the attack from immune cells. Cancer cells can express many immune inhibitory signalling proteins to cause ...immune cell dysfunction and apoptosis. One of these inhibitory molecules is programmed death-ligand-1 (PD-L1), which binds to programmed death-1 (PD-1) expressed on T-cells, B-cells, dendritic cells and natural killer T-cells to suppress anti-cancer immunity. Therefore, anti-PD-L1 and anti-PD-1 antibodies have been used for the treatment of cancer, showing promising outcomes. However, only a proportion of patients respond to the treatments. Further understanding of the regulation of PD-L1 expression could be helpful for the improvement of anti-PD-L1 and anti-PD-1 treatments. Studies have shown that PD-L1 expression is regulated by signalling pathways, transcriptional factors and epigenetic factors. In this review, we summarise the recent progress of the regulation of PD-L1 expression in cancer cells and propose a regulatory model for unified explanation. Both PI3K and MAPK pathways are involved in PD-L1 regulation but the downstream molecules that control PD-L1 and cell proliferation may differ. Transcriptional factors hypoxia-inducible factor-1α and signal transducer and activation of transcription-3 act on the promoter of PD-L1 to regulate its expression. In addition, microRNAs including miR-570, miR-513, miR-197, miR-34a and miR-200 negatively regulate PD-L1. Clinically, it could increase treatment efficacy of targeted therapy by choosing those molecules that control both PD-L1 expression and cell proliferation.
Abstract
Superconductivity in the cuprates is found to be intertwined with charge and spin density waves. Determining the interactions between the different types of order is crucial for ...understanding these important materials. Here, we elucidate the role of the charge density wave (CDW) in the prototypical cuprate La
1.885
Sr
0.115
CuO
4
, by studying the effects of large magnetic fields (
H
) up to 24 Tesla. At low temperatures (
T
), the observed CDW peaks reveal two distinct regions in the material: a majority phase with short-range CDW coexisting with superconductivity, and a minority phase with longer-range CDW coexisting with static spin density wave (SDW). With increasing magnetic field, the CDW first grows smoothly in a manner similar to the SDW. However, at high fields we discover a sudden increase in the CDW amplitude upon entering the vortex-liquid state. Our results signify strong coupling of the CDW to mobile superconducting vortices and link enhanced CDW amplitude with local superconducting pairing across the
H
−
T
phase diagram.
Fusion of heavy nuclei remains an area of intense research. Fusion reactions at extremely low energies between carbon and oxygen are important during the late stellar evolution and nucleosynthesis in ...massive stars. The quest to extend the periodic table of the elements relies on heavy-ion fusion to reach superheavy isotopes at the limit of mass and charge. Finally, fusion reactions involving radioactive nuclei elucidate the effects of loosely bound nucleons on many-particle quantum tunneling. In this article, recent experimental and theoretical developments in heavy-ion fusion research, in a wide range from deep sub-barrier energies to energies well above the interaction barrier, are reviewed. As several heavy-ion fusion reactions are of crucial importance in late-stage giant-star evolution, these reactions continue to be studied with better experimental and theoretical tools in order to provide improved input to astrophysical models. Also this area has seen significant progress in several different approaches to the problem of predicting the cross sections for formation and survival of these rare nuclei.
Label-free bio-sensing is a critical functionality underlying a variety of health- and security-related applications. Micro-/nano-photonic devices are well suited for this purpose and have emerged as ...promising platforms in recent years. Here we propose and demonstrate an approach that utilizes the optical spring effect in a high-Q coherent optomechanical oscillator to dramatically enhance the sensing resolution by orders of magnitude compared with conventional approaches, allowing us to detect single bovine serum albumin proteins with a molecular weight of 66 kDa at a signal-to-noise ratio of 16.8. The unique optical spring sensing approach opens up a distinctive avenue that not only enables biomolecule sensing and recognition at individual level, but is also of great promise for broad physical sensing applications that rely on sensitive detection of optical cavity resonance shift to probe external physical parameters.
Background
Oral fluconazole is used to treat vulvovaginal candidiasis during pregnancy. However, there are concerns regarding the pregnancy outcomes following exposure to fluconazole.
Objectives
To ...evaluate the pregnancy outcomes associated with exposure to oral fluconazole during the first trimester of pregnancy.
Search strategy
A systematic literature search was conducted to identify relevant studies published from inception until April 2019.
Selection criteria
Relevant English‐language citations using the terms oral fluconazole and pregnancy in humans.
Data collection
Two reviewers independently ed data and assessed study quality.
Main results
Oral fluconazole use during the first trimester of pregnancy was marginally associated with an increased risk of congenital malformations (odds ratio OR 1.09, 95% CI 0.99–1.2, P = 0.088; n = 6 studies), whereas in the subgroup analysis, this association existed only for high‐dose users (>150 mg) (OR 1. 19, 95% CI 1.01–1.4, P = 0.039; n = 2). Exposure to fluconazole also increased the risk of heart malformations (OR 1.31, 95% CI 1.09–1.57, P = 0.003; n = 4), cardiac septal defects (OR 1.3, 95% CI 1.1–1.67, P = 0.047; n = 3), and tetralogy of Fallot (OR 3.39 95% CI 1.71–6.74, P < 0.001; n = 2) in the offspring. In addition, exposure to fluconazole was significantly associated with an increased risk of spontaneous abortion (OR 1.99, 95% CI 1.38–2.88, P < 0.001; n = 3).
Conclusions
Oral fluconazole use during the first trimester of pregnancy appears to be associated with heart malformations and spontaneous abortion, but a causal link cannot be proven.
Tweetable
Oral fluconazole during the first trimester of pregnancy may be associated with unfavourable pregnancy outcomes.
Tweetable
Oral fluconazole during the first trimester of pregnancy may be associated with unfavourable pregnancy outcomes.
Continuum numerical modeling of dynamic crack propagation has been a great challenge over the past decade. This is particularly the case for anticracks in porous materials, as reported in sedimentary ...rocks, deep earthquakes, landslides, and snow avalanches, as material inter-penetration further complicates the problem. Here, on the basis of a new elastoplasticity model for porous cohesive materials and a large strain hybrid Eulerian-Lagrangian numerical method, we accurately reproduced the onset and propagation dynamics of anticracks observed in snow fracture experiments. The key ingredient consists of a modified strain-softening plastic flow rule that captures the complexity of porous materials under mixed-mode loading accounting for the interplay between cohesion loss and volumetric collapse. Our unified model represents a significant step forward as it simulates solid-fluid phase transitions in geomaterials which is of paramount importance to mitigate and forecast gravitational hazards.
The completion of the Arabidopsis thaliana genome sequence allows a comparative analysis of transcriptional regulators across the three eukaryotic kingdoms. Arabidopsis dedicates over 5% of its ...genome to code for more than 1500 transcription factors, about 45% of which are from families specific to plants. Arabidopsis transcription factors that belong to families common to all eukaryotes do not share significant similarity with those of the other kingdoms beyond the conserved DNA binding domains, many of which have been arranged in combinations specific to each lineage. The genome-wide comparison reveals the evolutionary generation of diversity in the regulation of transcription.
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