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"Hess, L"
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Lightning strikes as a major facilitator of prebiotic phosphorus reduction on early Earth
When hydrated, phosphides such as the mineral schreibersite, (Fe,Ni)
3
P, allow for the synthesis of important phosphorus-bearing organic compounds. Such phosphides are common accessory minerals in meteorites; consequently, meteorites are proposed to be a main source of prebiotic reactive phosphorus on early Earth. Here, we propose an alternative source for widespread phosphorus reduction, arguing that lightning strikes on early Earth potentially formed 10–1000 kg of phosphide and 100–10,000 kg of phosphite and hypophosphite annually. Therefore, lightning could have been a significant source of prebiotic, reactive phosphorus which would have been concentrated on landmasses in tropical regions. Lightning strikes could likewise provide a continual source of prebiotic reactive phosphorus independent of meteorite flux on other Earth-like planets, potentially facilitating the emergence of terrestrial life indefinitely.
Determining the origins of life on Earth is confounded by the fact that the sources of nutrients necessary to create early life forms remain mysterious. Here the authors show that lightning strikes could have supplied a major source of essential phosphorus on early Earth.
Journal Article
Sargent and Paris
\"Sargent and Paris explores the early career of American painter John Singer Sargent (1856-1925), from his arrival in Paris in 1874 as a precocious 18-year-old art student through the mid-1880s, when his infamous portrait Madame X was a scandalous success at the Paris Salon. Over the course of one extraordinary decade, Sargent achieved recognition by creating boldly ambitious portraits and figure paintings that pushed the boundaries of conventionality. Immersed in a cosmopolitan circle of artists, writers, and patrons, Sargent was able to navigate a successful path through the French exhibition system while achieving acclaim and awards. Beyond the portrait studio, he traveled in search of inspiration for his art--finding subjects in Italy, the Netherlands, Spain, and North Africa. This exhibition gathers Sargent's diverse works from this period to illuminate his path to becoming an artist, which was indelibly shaped by his experiences in the French capital. These visually stunning works provide a compelling view of the Paris art world of the late 19th century. The iconic Madame X, a beloved highlight of The Met collection, is the culmination of Sargent's early years in Paris. The exhibition will take an in-depth look at this captivating portrait and the numerous preparatory sketches, and it will be displayed alongside select portraits of Parisiennes by Sargent's contemporaries.\" -- Metropolitan Museum of Art website
BOOK
Drifting discrete Jovian radio bursts reveal acceleration processes related to Ganymede and the main aurora
Radio detection at high time-frequency resolutions is a powerful means of remotely studying electron acceleration processes. Radio bursts have characteristics (polarization, drift, periodicity) making them easier to detect than slowly variable emissions. They are not uncommon in solar system planetary magnetospheres, the powerful Jovian “short bursts (S-bursts)\" induced by the Io-Jupiter interaction being especially well-documented. Here we present a detection method of drifting radio bursts in terabytes of high resolution time-frequency data, applied to one month of ground-based Jupiter observations. Beyond the expected Io-Jupiter S-bursts, we find decameter S-bursts related to the Ganymede-Jupiter interaction and the main Jovian aurora, revealing ubiquitous Alfvénic electron acceleration in Jupiter’s high-latitude regions. Our observations show accelerated electron energies are distributed in two populations, kilo-electron-Volts and hundreds of electron-Volts. This detection technique may help characterizing inaccessible astrophysical sources such as exoplanets.
Jovian short bursts (S-bursts) are induced by the Io-Jupiter interaction. Here, the authors show a drifting radio burst detection method and report S-bursts related to Ganymede-Jupiter interaction and to Jovian aurora.
Journal Article
Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra
The ionospheric response to auroral precipitation at the giant planets is reviewed, using models and observations. The emission processes for aurorae at radio, infrared, visible, ultraviolet, and X-ray wavelengths are described, and exemplified using ground- and space-based observations. Comparisons between the emissions at different wavelengths are made, where possible, and interpreted in terms of precipitating particle characteristics or atmospheric conditions. Finally, the spatial distributions and dynamics of the various components of the aurorae (moon footprints, low-latitude, main oval, polar) are related to magnetospheric processes and boundaries, using theory, in situ, and remote observations, with the aim of distinguishing between those related to internally-driven dynamics, and those related to the solar wind interaction.
Journal Article
Phage display as a tool for vaccine and immunotherapy development
Bacteriophages, or phages, are viruses that specifically infect bacteria and coopt the cellular machinery to create more phage proteins, eventually resulting in the release of new phage particles. Phages are heavily utilized in bioengineering for applications ranging from tissue engineering scaffolds to immune signal delivery. Of specific interest to vaccines and immunotherapies, phages have demonstrated an ability to activate both the innate and adaptive immune systems. The genome of these viral particles can be harnessed for DNA vaccination, or the surface proteins can be exploited for antigen display. More specifically, genes that encode an antigen of interest can be spliced into the phage genome, allowing antigenic proteins or peptides to be displayed by fusion to phage capsid proteins. Phages therefore present antigens to immune cells in a highly ordered and repetitive manner. This review discusses the use of phage with adjuvanting activity as antigen delivery vehicles for vaccination against infectious disease and cancer.
Journal Article
Model of the Jovian magnetic field topology constrained by the Io auroral emissions
The determination of the internal magnetic field of Jupiter has been the object of many studies and publications. These models have been computed from the Pioneer, Voyager, and Ulysses measurements. Some models also use the position of the Io footprints as a constraint: the magnetic field lines mapping to the footprints must have their origins along Io's orbit. The use of this latter constraint to determine the internal magnetic field models greatly improved the modeling of the auroral emissions, in particular the radio ones, which strongly depends on the magnetic field geometry. This constraint is, however, not sufficient for allowing a completely accurate modeling. The fact that the footprint field line should map to a longitude close to Io's was not used, so that the azimuthal component of the magnetic field could not be precisely constrained. Moreover, a recent study showed the presence of a magnetic anomaly in the northern hemisphere, which has never been included in any spherical harmonic decomposition of the internal magnetic field. We compute a decomposition of the Jovian internal magnetic field into spherical harmonics, which allows for a more accurate mapping of the magnetic field lines crossing Io, Europa, and Ganymede orbits to the satellite footprints observed in UV. This model, named VIPAL, is mostly constrained by the Io footprint positions, including the longitudinal constraint, and normalized by the Voyager and Pioneer magnetic field measurements. We show that the surface magnetic fields predicted by our model are more consistent with the observed frequencies of the Jovian radio emissions than those predicted by previous models. Key Points A more accurate magnetic field model can be computed from the mapping of Io's fo This model is consistent with the magnetometer measurements This model permits a better description of the satellite‐related aurorae
Journal Article
Relationships between forest cover and fish diversity in the Amazon River floodplain
1. Habitat degradation leads to biodiversity loss and concomitant changes in ecosystem processes. Tropical river floodplains are highly threatened by land cover changes and support high biodiversity and important ecosystem services, but the extent to which changes in floodplain land cover affect fish biodiversity remains unknown. 2. We combined fish and environmental data collected in situ and satellite-mapped landscape features to evaluate how fish species with different ecological strategies and assemblage structures respond to deforestation in floodplains of the Amazon River. We surveyed 462 floodplain habitats distributed along a gradient of land cover, from largely forested to severely deforested. Rather than analyse only taxonomic metrics, we employed an integrative approach that simultaneously considers different aspects of fish biodiversity (i.e. β diversity and taxonomic and functional assemblage structure) to facilitate mechanistic interpretations of the influence of land cover. 3. Spatial patterns of fish biodiversity in the Amazon River floodplain were strongly associated with forest cover as well as local environmental conditions linked to landscape gradients. Several species and functional groups defined by life-history, feeding, swimming/microhabitat-use strategies were positively associated with forest cover. Other species, including some that would usually be considered habitat generalists and species directly dependent on autochthonous resources (e.g. planktivores), were most common in areas dominated by herbaceous vegetation or open water habitats associated with the opposite extreme of the forest cover gradient. β diversity and the degree of uniqueness of species combinations within habitats were also positively associated with forest cover. 4. Synthesis and applications. Our results demonstrating that spatial patterns of fish biodiversity are associated with forest cover, indicate that deforestation of floodplains of the Amazon River results in spatial homogenization of fish assemblages and reduced functional diversity at both local and regional scales. Floodplains world-wide have undergone major land cover changes, with forest loss projected to increase during the next decades. Conserving fish diversity in these ecosystems requires protecting mosaics of both aquatic habitats and floodplain vegetation, with sufficient forest cover being critically important.
Journal Article
Syphilis Trends among Men Who Have Sex with Men in the United States and Western Europe: A Systematic Review of Trend Studies Published between 2004 and 2015
Globally, men who have sex with men (MSM) are disproportionately burdened with syphilis. This review describes the published literature on trends in syphilis infections among MSM in the US and Western Europe from 1998, the period with the fewest syphilis infections in both geographical areas, onwards. We also describe disparities in syphilis trends among various sub-populations of MSM. We searched electronic databases (Medline, Embase, Global Health, PsychInfo, CAB Abstracts, CINAHL, Sociological Abstracts, Web of Science, Cochrane Library, and LILACS) for peer-reviewed journal articles that were published between January 2004 and June 2015 and reported on syphilis cases among MSM at multiple time points from 1998 onwards. Ten articles (12 syphilis trend studies/reports) from the US and eight articles (12 syphilis trend studies/reports) from Western Europe were identified and included in this review. Taken together, our findings indicate an increase in the numbers and rates (per 100,000) of syphilis infections among MSM in the US and Western Europe since 1998. Disparities in the syphilis trends among MSM were also noted, with greater increases observed among HIV-positive MSM than HIV-negative MSM in both the US and Western Europe. In the US, racial minority MSM and MSM between 20 and 29 years accounted for the greatest increases in syphilis infections over time whereas White MSM accounted for most syphilis infections over time in Western Europe. Multiple strategies, including strengthening and targeting current syphilis screening and testing programs, and the prompt treatment of syphilis cases are warranted to address the increase in syphilis infections among all MSM in the US and Western Europe, but particularly among HIV-infected MSM, racial minority MSM, and young MSM in the US.
Journal Article
Power transmission and particle acceleration along the Io flux tube
Io's motion relative to the Jovian magnetic field generates a power of about 1012 W, which is thought to propagate as an Alfvén wave along the magnetic field line. This power is transmitted to the electrons, which will then precipitate and generate the observed auroral phenomena from UV to radio wavelengths. A more detailed look at this hypothesis shows some difficulties: Can the Alfvén waves escape the torus or are they trapped inside? Where and how are the particles accelerated? In which direction? Is there enough power transmitted to the particles to explain the strong brightness of the auroral emissions in UV, IR, visible, and radio? In other words, can we make a global, consistent model of the Io‐Jupiter interaction that matches all the observations? To answer these questions, we review the models and studies that have been proposed so far. We show that the Alfvén waves need to be filamented by a turbulent cascade process and accelerate the electrons at high latitude in order to explain the observations and to form a consistent scheme of the Io‐Jupiter interaction.
Journal Article