Search

Due to its peculiar and highly variable nature, the blazar 3C 454.3 has been extensively monitored by the WEBT team. Here, we present for the first time these long-term optical flux and color variability results using data acquired in B , V , R , and I bands over a time span of about two decades. We include data from WEBT collaborators and public archives such as SMARTS, Steward Observatory, and Zwicky Transient Facility. The data are binned and segmented to study the source over this long term when more regular sampling was available. During our study, the long-term spectral variability reveals a redder-when-brighter trend, which, however, stabilizes at a particular brightness cutoff of ∼14.5 mag in the I band, after which it saturates and evolves into a complex state. This trend indicates increasing dominance of jet emission over accretion disk (AD) emission until jet emission completely dominates. Plots of the variation in spectral index (following F _ν ∝ ν ^− ^α ) reveal a bimodal distribution using a one-day binning. These correlate with two extreme phases of 3C 454.3, an outburst or high-flux state and a quiescent or low-flux state, which are respectively jet- and AD-dominated. We have also conducted intraday variability studies of nine light curves and found that six of them are variable. Discrete correlation function analysis between different pairs of optical wave bands peaks at zero lags, indicating cospatial emission in different optical bands.

We study the broadband emission of Mrk 501 using multiwavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi's Large Area Telescope (LAT), NuSTAR, Swift, GASP-WEBT, and the Owens Valley Radio Observatory. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wave bands, with the highest occurring at X-rays and very-high-energy (VHE) γ -rays. A significant correlation (>3 σ ) between X-rays and VHE γ -rays is measured, supporting leptonic scenarios to explain the variable parts of the emission, also during low activity. This is further supported when we extend our data from 2008 to 2020, and identify, for the first time, significant correlations between the Swift X-Ray Telescope and Fermi-LAT. We additionally find correlations between high-energy γ -rays and radio, with the radio lagging by more than 100 days, placing the γ -ray emission zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501 showed a historically low activity in X-rays and VHE γ -rays from mid-2017 to mid-2019 with a stable VHE flux (>0.2 TeV) of 5% the emission of the Crab Nebula. The broadband spectral energy distribution (SED) of this 2 yr long low state, the potential baseline emission of Mrk 501, can be characterized with one-zone leptonic models, and with (lepto)-hadronic models fulfilling neutrino flux constraints from IceCube. We explore the time evolution of the SED toward the low state, revealing that the stable baseline emission may be ascribed to a standing shock, and the variable emission to an additional expanding or traveling shock.

Objectives: Preeclampsia (PE) is a major cause of maternal and fetal mortality, and preterm birth. Previous studies indicate that lipid-apheresis may prolong pregnancy, namely heparin-mediated extracorporeal LDL-precipitation (HELP)- and dextran sulfate cellulose (DSC)-apheresis. We now report on double membrane plasmapheresis (DFPP) in early-onset preeclampsia (eoPE)., Study Design: Open pilot study assessing the prolongation of pregnancy in PE by lipoprotein-apheresis (DRKS00004527). Two women with eoPE were treated by DFPP and compared to a historical cohort of 6 patients with eoPE treated by HELP-apheresis (NCT01967355)., Main Outcome Measures: Clinical outcome of mothers and babies and prolongation of pregnancies (time of admission to birth)., Results: Patient 1 (33y; 22 + 5/7GW) received 4 DFPP. Delivery day 19; birthweight 270 g; weight at discharge 2134 g on day 132. Patient 2 (35y; 21 + 4/7GW) received 2 DFPP. Delivery day 19; birthweight 465 g; weight at discharge 2540 g on day 104. DFPP was well tolerated by both patients., Conclusions: DFPP proved to be save and pregnancies remained stable as long as 19 days. Although babies were born very preterm both babies could finally be dismissed from hospital. No relevant clinical differences between DFPP and HELP-apheresis could be observed. Therefore, DFPP may extend the range of available apheresis techniques to prolong pregnancies in early-onset preeclampsia. However, further studies are necessary to gain more information. REGISTER: (DRKS00004527)., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Blazars are active galactic nuclei (AGN) with relativistic jets whose non-thermal radiation is extremely variable on various timescales 1-3 . This variability seems mostly random, although some quasi-periodic oscillations (QPOs), implying systematic processes, have been reported in blazars and other AGN. QPOs with timescales of days or hours are especially rare 4 in AGN and their nature is highly debated, explained by emitting plasma moving helically inside the jet 5 , plasma instabilities 6,7 or orbital motion in an accretion disc 7,8 . Here we report results of intense optical and γ-ray flux monitoring of BL Lacertae (BL Lac) during a dramatic outburst in 2020 (ref.  9 ). BL Lac, the prototype of a subclass of blazars 10 , is powered by a 1.7 × 10 8  M Sun (ref.  11 ) black hole in an elliptical galaxy (distance = 313 megaparsecs (ref.  12 )). Our observations show QPOs of optical flux and linear polarization, and γ-ray flux, with cycles as short as approximately 13 h during the highest state of the outburst. The QPO properties match the expectations of current-driven kink instabilities 6 near a recollimation shock about 5 parsecs (pc) from the black hole in the wake of an apparent superluminal feature moving down the jet. Such a kink is apparent in a microwave Very Long Baseline Array (VLBA) image., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Microplastics are solid polymer particles with a wide variety of surface properties, found in most waterbodies, and known as carriers of distinct microbial communities affecting the fate of the particles in the environment. Little is known about the formation of mineral deposits on microplastics and how these deposits connect to microbial assemblages and affect the physicochemical properties of the particles. In addition, most of the available research on this topic is based on large microplastics with sizes between 100 μm and up to 5 mm, rather than the small microplastics often found in drinking water sources. To narrow this gap in our understanding of environmental effects on small microplastics, two types of small microplastics made of two distinct polymers, poly(methyl methacrylate) (PMMA) and poly(tetrafluoroethylene) (PTFE) with sizes ranging from 15 to 150 μm, were incubated for six months in unprocessed and processed drinking water with increasing ionic concentration to allow for the formation of mineral deposits and microbial assemblages. Spatially resolved analysis with fluorescent in situ hybridization and confocal Raman microscopic imaging revealed deposits of calcium carbonates and scattered microbial assemblages on all microplastics, with structure, extend, and microbial association with the carbonates depending on the respective microplastic. Notably, PTFE floatation was overcome after three months in unprocessed drinking water but remained unchanged in processed drinking water, whereas PMMA appeared unaffected, indicating that the fate of microplastics in the environment may depend on polymer type and the encountered aquatic conditions forming mineral and microbial attachments to the particle surface., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The membrane-bound proton-pumping pyrophosphatase (V-PPase), together with the V-type H + -ATPase, generates the proton motive force that drives vacuolar membrane solute transport. Transgenic plants constitutively overexpressing V-PPases were shown to have improved salinity tolerance, but the relative impact of increasing PP i hydrolysis and proton-pumping functions has yet to be dissected. For a better understanding of the molecular processes underlying V-PPase-dependent salt tolerance, we transiently overexpressed the pyrophosphate-driven proton pump (NbVHP) in Nicotiana benthamiana leaves and studied its functional properties in relation to salt treatment by primarily using patch-clamp, impalement electrodes and pH imaging. NbVHP overexpression led to higher vacuolar proton currents and vacuolar acidification. After 3 d in salt-untreated conditions, V-PPase-overexpressing leaves showed a drop in photosynthetic capacity, plasma membrane depolarization and eventual leaf necrosis. Salt, however, rescued NbVHP-hyperactive cells from cell death. Furthermore, a salt-induced rise in V-PPase but not of V-ATPase pump currents was detected in nontransformed plants. The results indicate that under normal growth conditions, plants need to regulate the V-PPase pump activity to avoid hyperactivity and its negative feedback on cell viability. Nonetheless, V-PPase proton pump function becomes increasingly important under salt stress for generating the pH gradient necessary for vacuolar proton-coupled Na + sequestration., (© 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.)

Carnivorous plants, such as the Venus flytrap (Dionaea muscipula), depend on an animal diet when grown in nutrient-poor soils. When an insect visits the trap and tilts the mechanosensors on the inner surface, action potentials (APs) are fired. After a moving object elicits two APs, the trap snaps shut, encaging the victim. Panicking preys repeatedly touch the trigger hairs over the subsequent hours, leading to a hermetically closed trap, which via the gland-based endocrine system is flooded by a prey-decomposing acidic enzyme cocktail. Here, we asked the question as to how many times trigger hairs have to be stimulated (e.g., now many APs are required) for the flytrap to recognize an encaged object as potential food, thus making it worthwhile activating the glands. By applying a series of trigger-hair stimulations, we found that the touch hormone jasmonic acid (JA) signaling pathway is activated after the second stimulus, while more than three APs are required to trigger an expression of genes encoding prey-degrading hydrolases, and that this expression is proportional to the number of mechanical stimulations. A decomposing animal contains a sodium load, and we have found that these sodium ions enter the capture organ via glands. We identified a flytrap sodium channel DmHKT1 as responsible for this sodium acquisition, with the number of transcripts expressed being dependent on the number of mechano-electric stimulations. Hence, the number of APs a victim triggers while trying to break out of the trap identifies the moving prey as a struggling Na(+)-rich animal and nutrition for the plant., (Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.)