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- Camilo, F., et al.
(author)
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Revival of the Magnetar PSR J1622-4950: Observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR
- 2018
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In: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 856:2
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Journal article (peer-reviewed)abstract
- New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100 larger than during its dormant state. The X-ray flux one month after reactivation was at least 800 larger than during quiescence, and has been decaying exponentially on a 111 19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.
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- Frenken, T., et al.
(author)
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Integrating chytrid fungal parasites into plankton ecology: research gaps and needs
- 2017
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In: Environmental Microbiology. - : Wiley. - 1462-2912. ; 19:10, s. 3802-3822
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Research review (peer-reviewed)abstract
- Chytridiomycota, often referred to as chytrids, can be virulent parasites with the potential to inflict mass mortalities on hosts, causing e.g. changes in phytoplankton size distributions and succession, and the delay or suppression of bloom events. Molecular environmental surveys have revealed an unexpectedly large diversity of chytrids across a wide range of aquatic ecosystems worldwide. As a result, scientific interest towards fungal parasites of phytoplankton has been gaining momentum in the past few years. Yet, we still know little about the ecology of chytrids, their life cycles, phylogeny, host specificity and range. Information on the contribution of chytrids to trophic interactions, as well as co-evolutionary feedbacks of fungal parasitism on host populations is also limited. This paper synthesizes ideas stressing the multifaceted biological relevance of phytoplankton chytridiomycosis, resulting from discussions among an international team of chytrid researchers. It presents our view on the most pressing research needs for promoting the integration of chytrid fungi into aquatic ecology.
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- van Houten, C. B., et al.
(author)
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Antibiotic misuse in respiratory tract infections in children and adultsa prospective, multicentre study (TAILORED Treatment)
- 2019
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In: European Journal of Clinical Microbiology & Infectious Diseases. - : Springer Science and Business Media LLC. - 0934-9723 .- 1435-4373. ; 38:3, s. 505-514
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Journal article (peer-reviewed)abstract
- Respiratory tract infections (RTI) are more commonly caused by viral pathogens in children than in adults. Surprisingly, little is known about antibiotic use in children as compared to adults with RTI. This prospective study aimed to determine antibiotic misuse in children and adults with RTI, using an expert panel reference standard, in order to prioritise the target age population for antibiotic stewardship interventions. We recruited children and adults who presented at the emergency department or were hospitalised with clinical presentation of RTI in The Netherlands and Israel. A panel of three experienced physicians adjudicated a reference standard diagnosis (i.e. bacterial or viral infection) for all the patients using all available clinical and laboratory information, including a 28-day follow-up assessment. The cohort included 284 children and 232 adults with RTI (median age, 1.3years and 64.5years, respectively). The proportion of viral infections was larger in children than in adults (209(74%) versus 89(38%), p<0.001). In case of viral RTI, antibiotics were prescribed (i.e. overuse) less frequently in children than in adults (77/209 (37%) versus 74/89 (83%), p<0.001). One (1%) child and three (2%) adults with bacterial infection were not treated with antibiotics (i.e. underuse); all were mild cases. This international, prospective study confirms major antibiotic overuse in patients with RTI. Viral infection is more common in children, but antibiotic overuse is more frequent in adults with viral RTI. Together, these findings support the need for effective interventions to decrease antibiotic overuse in RTI patients of all ages.
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- Lewandowska, A. M., et al.
(author)
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The influence of balanced and imbalanced resource supply on biodiversity-functioning relationship across ecosystems
- 2016
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In: Philosophical Transactions of the Royal Society B-Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 371:1694
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Journal article (peer-reviewed)abstract
- Numerous studies show that increasing species richness leads to higher ecosystem productivity. This effect is often attributed to more efficient portioning of multiple resources in communities with higher numbers of competing species, indicating the role of resource supply and stoichiometry for biodiversity ecosystern functioning relationships. Here, we merged theory on ecological stoichiometry with a framework of biodiversity ecosystem functioning to understand how resource use transfers into primary production. We applied a structural equation model to define patterns of diversity productivity relationships with respect to available resources. Meta-analysis was used to summarize the findings across ecosystem types ranging from aquatic ecosystems to grasslands and forests. As hypothesized, resource supply increased realized productivity and richness, but we found significant differences between ecosystems and study types. Increased richness was associated with increased productivity, although this effect was not seen in experiments. More even communities had lower productivity, indicating that biomass production is often maintained by a few dominant species, and reduced dominance generally reduced ecosystem productivity. This synthesis, which integrates observational and experimental studies in a variety of ecosystems and geographical regions, exposes common pattems and differences in biodiversity functioning relationships, and increases the mechanistic understanding of changes in ecosystems productivity.
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- Wohlrab, S., et al.
(author)
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Ocean acidification increases domoic acid contents during a spring to summer succession of coastal phytoplankton
- 2020
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In: Harmful Algae. - : Elsevier BV. - 1568-9883. ; 92
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Journal article (peer-reviewed)abstract
- Enrichment of the oceans with CO2 may be beneficial for some marine phytoplankton, including harmful algae. Numerous laboratory experiments provided valuable insights into the effects of elevated pCO(2) on the growth and physiology of harmful algal species, including the production of phycotoxins. Experiments close to natural conditions are the next step to improve predictions, as they consider the complex interplay between biotic and abiotic factors that can confound the direct effects of ocean acidification. We therefore investigated the effect of ocean acidification on the occurrence and abundance of phycotoxins in bulk plankton samples during a long-term mesocosm experiment in the Gullmar Fjord, Sweden, an area frequently experiencing harmful algal blooms. During the experimental period, a total of seven phycotoxin-producing harmful algal genera were identified in the fjord, and in accordance, six toxin classes were detected. However, within the mesocosms, only domoic acid and the corresponding producer Pseudo-nitzschia spp. was observed. Despite high variation within treatments, significantly higher particulate domoic acid contents were measured in the mesocosms with elevated pCO(2). Higher particulate domoic acid contents were additionally associated with macronutrient limitation. The risks associated with potentially higher phycotoxin levels in the future ocean warrants attention and should be considered in prospective monitoring strategies for coastal marine waters.
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- Veldhuis Kroeze, Edwin J. B., et al.
(author)
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Consecutive CT in vivo lung imaging as quantitative parameter of influenza vaccine efficacy in the ferret model
- 2012
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In: Vaccine. - : Elsevier. - 0264-410X .- 1873-2518. ; 30:51, s. 7391-7394
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Journal article (peer-reviewed)abstract
- Preclinical vaccine efficacy studies are generally limited to certain read out parameters such as assessment of virus titers in swabs and organs, clinical signs, serum antibody titers, and pathological changes. These parameters are not always routinely applied and not always scheduled in a logical standardized way. We used computed tomography (CT) imaging as additional and novel read out parameter in a vaccine efficacy study by quantifying alterations in aerated lung volumes in ferrets challenged with the 2009 pandemic A/H1N1 influenza virus.Vaccination protected from marked variations in aerated lung volumes compared to naive controls. The vaccinated group showed a daily gradual mean reduction with a maximum of 7.8%, whereas the controls showed a maximum of 14.3% reduction. The pulmonary opacities evident on CT images were most pronounced in the placebo-treated controls, and corresponded to significantly increased relative lung weights at necropsy.This study shows that consecutive in vivo CT imaging allows for a day to day read out of vaccine efficacy by quantification of altered aerated lung volumes.
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