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The rocky shores of the north-east Atlantic have been long studied. Our focus is from Gibraltar to Norway plus the Azores and Iceland. Phylogeographic processes shape biogeographic patterns of biodiversity. Long-term and broadscale studies have shown the responses of biota to past climate fluctuations and more recent anthropogenic climate change. Inter- and intra-specific species interactions along sharp local environmental gradients shape distributions and community structure and hence ecosystem functioning. Shifts in domination by fucoids in shelter to barnacles/mussels in exposure are mediated by grazing by patellid limpets. Further south fucoids become increasingly rare, with species disappearing or restricted to estuarine refuges, caused by greater desiccation and grazing pressure. Mesoscale processes influence bottom-up nutrient forcing and larval supply, hence affecting species abundance and distribution, and can be proximate factors setting range edges (e.g., the English Channel, the Iberian Peninsula). Impacts of invasive non-native species are reviewed. Knowledge gaps such as the work on rockpools and host–parasite dynamics are also outlined.
This paper describes a model of electron energization and cyclotron-maser emission applicable to astrophysical magnetized collisionless shocks. It is motivated by the work of Begelman, Ergun and Rees [Astrophys. J. 625, 51 (2005)] who argued that the cyclotron-maser instability occurs in localized magnetized collisionless shocks such as those expected in blazar jets. We report on recent research carried out to investigate electron acceleration at collisionless shocks and maser radiation associated with the accelerated electrons. We describe how electrons accelerated by lower-hybrid waves at collisionless shocks generate cyclotron-maser radiation when the accelerated electrons move into regions of stronger magnetic fields. The electrons are accelerated along the magnetic field and magnetically compressed leading to the formation of an electron velocity distribution having a horseshoe shape due to conservation of the electron magnetic moment. Under certain conditions the horseshoe electron velocity distribution function is unstable to the cyclotron-maser instability [Bingham and Cairns, Phys. Plasmas 7, 3089 (2000); Melrose, Rev. Mod. Plasma Phys. 1, 5 (2017)].
The chemical composition of soil from the Glasgow (UK) urban area was used to identify the controls on the availability of potentially harmful elements (PHEs) in soil to humans. Total and bioaccessible concentrations of arsenic (As), chromium (Cr) and lead (Pb) in 27 soil samples, collected from different land uses, were coupled to information on their solid-phase partitioning derived from sequential extraction data. The total element concentrations in the soils were in the range <0.1–135mgkg–1 for As; 65–3680mgkg–1 for Cr and 126–2160mgkg–1 for Pb, with bioaccessible concentrations averaging 27, 5 and 27% of the total values, respectively. Land use does not appear to be a predictor of contamination; however, the history of the contamination is critically important. The Chemometric Identification of Substrates and Element Distribution (CISED) sequential chemical extraction and associated self-modelling mixture resolution analysis identified three sample groupings and 16 geochemically distinct phases (substrates). These were related to iron (n=3), aluminium–silicon (Al–Si; n=2), calcium (n=3), phosphorus (n=1), magnesium (Mg; n=3), manganese (n=1) and easily extractable (n=3), which was predominantly made up of sodium and sulphur. As, Cr and Pb were respectively found in 9, 10 and 12 of the identified phases, with bioaccessible As predominantly associated with easily extractable phases, bioaccessible Cr with the Mg-dominated phases and bioaccessible Pb with both the Mg-dominated and Al–Si phases. Using a combination of the Unified Barge Method to measure the bioaccessibility of PHEs and CISED to identify the geochemical sources has allowed a much better understanding of the complexity of PHE mobility in the Glasgow urban environment. This approach can be applied to other urban environments and cases of soil contamination, and made part of land-use planning.
In this work we have conducted a study on the radiative and spectroscopic properties of the radiative precursor and the post-shock region from experiments with radiative shocks in xenon performed at the Orion laser facility. The study is based on post-processing of radiation-hydrodynamics simulations of the experiment. In particular, we have analyzed the thermodynamic regime of the plasma, the charge state distributions, the monochromatic opacities and emissivities, and the specific intensities for plasma conditions of both regions. The study of the intensities is a useful tool to estimate ranges of electron temperatures present in the xenon plasma in these experiments and the analysis performed of the microscopic properties commented above helps to better understand the intensity spectra. Finally, a theoretical analysis of the possibility of the onset of isobaric thermal instabilities in the post-shock has been made, concluding that the instabilities obtained in the radiative-hydrodynamic simulations could be thermal ones due to strong radiative cooling.
Theorists and researchers have linked resilience with a host of positive psychological and physical health outcomes. This paper examines perceptions of resilience and physical health symptoms in a sample of individuals exposed to multiple community disasters following involvement in integrated mental health services.
A multiwave naturalistic design was used to follow 762 adult clinic patients (72% female; 28% minority status), ages 18-92 years (mean age=40 years), who were evaluated for resilience and physical health symptoms prior to receiving services and at 1, 3, and 6 months’ follow-up.
Data indicated increases in perceptions of resilience and decreased physical health symptoms reported over time. Results also indicated that resilience predicted physical health symptoms, such that resilience and physical health symptoms were negatively associated (ie, improved resilience was associated with decreases in physical health symptoms). These effects were primarily observed for those individuals with previous exposure to natural disasters.
Findings provide correlational evidence for behavioral health treatment provided as part of a stepped-care, collaborative model in reducing physical health symptoms and increasing resilience post-disaster. Controlled trials are warranted. (Disaster Med Public Health Preparedness. 2019;13:223–229)
The Neotoma Paleoecology Database is a community-curated data resource that supports interdisciplinary global change research by enabling broad-scale studies of taxon and community diversity, distributions, and dynamics during the large environmental changes of the past. By consolidating many kinds of data into a common repository, Neotoma lowers costs of paleodata management, makes paleoecological data openly available, and offers a high-quality, curated resource. Neotoma’s distributed scientific governance model is flexible and scalable, with many open pathways for participation by new members, data contributors, stewards, and research communities. The Neotoma data model supports, or can be extended to support, any kind of paleoecological or paleoenvironmental data from sedimentary archives. Data additions to Neotoma are growing and now include >3.8 million observations, >17,000 datasets, and >9200 sites. Dataset types currently include fossil pollen, vertebrates, diatoms, ostracodes, macroinvertebrates, plant macrofossils, insects, testate amoebae, geochronological data, and the recently added organic biomarkers, stable isotopes, and specimen-level data. Multiple avenues exist to obtain Neotoma data, including the Explorer map-based interface, an application programming interface, the neotoma R package, and digital object identifiers. As the volume and variety of scientific data grow, community-curated data resources such as Neotoma have become foundational infrastructure for big data science.
“Deep learning” is finding more and more applications everywhere, and astronomy is not an exception. This talk described the application of convolutional neural networks to time-domain astronomy, specifically to light-curves of sources. The work that is discussed is based on a published paper to which reference can be made for more detail. The talk finished with a note cautioning new practitioners about the pitfalls lurking in out-of-the-box use of deep-learning techniques.
The Universe is permeated by hot, turbulent, magnetized plasmas. Turbulent plasma is a major constituent of active galactic nuclei, supernova remnants, the intergalactic and interstellar medium, the solar corona, the solar wind and the Earth’s magnetosphere, just to mention a few examples. Energy dissipation of turbulent fluctuations plays a key role in plasma heating and energization, yet we still do not understand the underlying physical mechanisms involved. THOR is a mission designed to answer the questions of how turbulent plasma is heated and particles accelerated, how the dissipated energy is partitioned and how dissipation operates in different regimes of turbulence. THOR is a single-spacecraft mission with an orbit tuned to maximize data return from regions in near-Earth space – magnetosheath, shock, foreshock and pristine solar wind – featuring different kinds of turbulence. Here we summarize the THOR proposal submitted on 15 January 2015 to the ‘Call for a Medium-size mission opportunity in ESAs Science Programme for a launch in 2025 (M4)’. THOR has been selected by European Space Agency (ESA) for the study phase.
Twenty-two consecutive VLBI images of supernova 1993J in the galaxy M81 taken over 7 years show, in unprecedented detail, the dynamic evolution of the expanding radio shell of an exploded star. High precision astrometry using phase-referencing shows that the supernova expands isotropically, and that its geometric center has a formal proper motion of 190±110 km s−1 w.r.t. the core of M81. Systematic changes in the images most likely reflect a pattern of inhomogeneities in the medium left over from the progenitor star, or possibly instabilities in the expanding shell. As the shockfront sweeps up the medium, it is progressively decelerated, and after 7 years it has slowed to less than 1/2 its original expansion velocity. SN1993J is likely now entering the early stages of the adiabatic phase common in much older supernova remnants.
This triennium has in general not been one of spectacular new developments in photometric of polarimetric techniques; rather, existing techniques have been improved and are being exploited by more observatories than before. For this reason, the previous report (31.113.097) should be consulted for a broad survey of the subject, while the present has the character of a progress report.
Twenty consecutive VLBI images of supernova 1993J in M81 from the time of explosion to the present show the dynamic evolution of the expanding radio shell of an exploded star. No clear sign of a pulsar nebula, expected to have a spectral luminosity 10 to 1,000 times larger than that of the Crab, has yet been seen. The upper limit on the brightness at 8.4 GHz in the center of the shell in one of the latest images is 0.15 mJy per beam of 0.4 mas2, corresponding to a spectral luminosity of that of the Crab. Any nebula that may have formed in the center is probably still obscured by the surrounding thermal matter with no substantial filamentation having yet occurred in the latter.
The linear polarization of the Crab pulsar as a function of pulse phase was observed by the High Speed Photometer on the Hubble Space Telescope in March, 1993. Observations were obtained in a bandpass centered on 2770 A using a 0.25 ms sample time, corresponding to a time resolution of 0.0075 in pulse phase. The UV polarization of the pulsar [Fig. 1] is strikingly similar to that observed in the visible (cf. Smith et al. 1988). The same values of polarization and the same swing of position angle occur through the main and secondary pulses. The polarization pulse profile must be essentially wavelength independent at frequencies above the infrared.
The positions of circumstellar molecular masers relative to each other, to the central star, and to the compact extragalactic sources are of astrophysical and astrometrical interest. The SiO masers at λ = 7 mm are especially interesting as the maser spots are located very close to the photosphere of the star. For astrometry we would like to see a proper distribution of the maser spots and several epochs of observations in order to estimate the position of the central star and eventual motions of the spots.
The optical position of this star can be determined with ground-based astrometric facilities, and many of the stars showing SiO emission are in the Hipparcos catalogue. A link between the Optical and Radio Reference Frames is achieved in a second step relating the maser spot positions to the Extragalactic Reference Frame (EGRF) established with VLBI (Baudry et al., 1984).
We assessed evidence of exposure to viruses and bacteria in an unmanaged and long-isolated population of Soay sheep (Ovis aries) inhabiting Hirta, in the St Kilda archipelago, 65 km west of Benbecula in the Outer Hebrides of Scotland. The sheep harbour many metazoan and protozoan parasites but their exposure to viral and bacterial pathogens is unknown. We tested for herpes viral DNA in leucocytes and found that 21 of 42 tested sheep were infected with ovine herpesvirus 2 (OHV-2). We also tested 750 plasma samples collected between 1997 and 2010 for evidence of exposure to seven other viral and bacterial agents common in domestic Scottish sheep. We found evidence of exposure to Leptospira spp., with overall seroprevalence of 6·5%. However, serological evidence indicated that the population had not been exposed to border disease, parainfluenza, maedi-visna, or orf viruses, nor to Chlamydia abortus. Some sheep tested positive for antibodies against Mycobacterium avium subsp. paratuberculosis (MAP) but, in the absence of retrospective faecal samples, the presence of this infection could not be confirmed. The roles of importation, the pathogen–host interaction, nematode co-infection and local transmission warrant future investigation, to elucidate the transmission ecology and fitness effects of the few viral and bacterial pathogens on Hirta.