Author Correction: Superluminal motion of a relativistic jet in the neutron-star merger GW170817.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Superluminal motion of a relativistic jet in the neutron-star merger GW170817.

The binary neutron-star merger GW1708171 was accompanied by radiation across the electromagnetic spectrum2 and localized2 to the galaxy NGC 4993 at a distance3 of about 41 megaparsecs from Earth. The radio and X-ray afterglows of GW170817 exhibited delayed onset4-7, a gradual increase8 in the emission with time (proportional to t0.8) to a peak about 150 days after the merger event9, followed by a relatively rapid decline9,10. So far, various models have been proposed to explain the afterglow emission, including a choked-jet cocoon4,8,11-13 and a successful-jet cocoon4,8,11-18 (also called a structured jet). However, the observational data have remained inconclusive10,15,19,20 as to whether GW170817 launched a successful relativistic jet. Here we report radio observations using very long-baseline interferometry. We find that the compact radio source associated with GW170817 exhibits superluminal apparent motion between 75 days and 230 days after the merger event. This measurement breaks the degeneracy between the choked- and successful-jet cocoon models and indicates that, although the early-time radio emission was powered by a wide-angle outflow8 (a cocoon), the late-time emission was most probably dominated by an energetic and narrowly collimated jet (with an opening angle of less than five degrees) and observed from a viewing angle of about 20 degrees. The imaging of a collimated relativistic outflow emerging from GW170817 adds substantial weight to the evidence linking binary neutron-star mergers and short γ-ray bursts.

A mildly relativistic wide-angle outflow in the neutron-star merger event GW170817.

GW170817 was the first gravitational-wave detection of a binary neutron-star merger. It was accompanied by radiation across the electromagnetic spectrum and localized to the galaxy NGC 4993 at a distance of 40 megaparsecs. It has been proposed that the observed γ-ray, X-ray and radio emission is due to an ultra-relativistic jet being launched during the merger (and successfully breaking out of the surrounding material), directed away from our line of sight (off-axis). The presence of such a jet is predicted from models that posit neutron-star mergers as the drivers of short hard-γ-ray bursts. Here we report that the radio light curve of GW170817 has no direct signature of the afterglow of an off-axis jet. Although we cannot completely rule out the existence of a jet directed away from the line of sight, the observed γ-ray emission could not have originated from such a jet. Instead, the radio data require the existence of a mildly relativistic wide-angle outflow moving towards us. This outflow could be the high-velocity tail of the neutron-rich material that was ejected dynamically during the merger, or a cocoon of material that breaks out when a jet launched during the merger transfers its energy to the dynamical ejecta. Because the cocoon model explains the radio light curve of GW170817, as well as the γ-ray and X-ray emission (and possibly also the ultraviolet and optical emission), it is the model that is most consistent with the observational data. Cocoons may be a ubiquitous phenomenon produced in neutron-star mergers, giving rise to a hitherto unidentified population of radio, ultraviolet, X-ray and γ-ray transients in the local Universe.

Synchronization and decoherence in a self-excited inertia-wheel multiple rigid-body dynamical system.

We investigate the synchronization and decoherence of a self-excited inertia wheel multiple rigid-body dynamical system. We employ an Euler-Lagrange formulation to derive a nondimensional state space that governs the dynamics of a coupled pendula array where each element incorporates an inertia wheel. The dynamical system exhibits multiple equilibria, periodic limit-cycle oscillations, quasiperiodic, and chaotic oscillations and rotations. We make use of a combined approach including a singular perturbation multiple time scale and numerical bifurcation methodologies to determine the existence of synchronized and decoherent solutions in both weakly and strongly nonlinear regimes, respectively. The analysis reveals that synchronous oscillations are in-phase, whereas quasiperiodic oscillations are anti-phase. Furthermore, the non-stationary rotations are found to exhibit combinations of oscillations and rotations of the individual elements that are asynchronous. A Kuramoto order parameter analysis of representative solutions in various bifurcation regimes reveals the existence of chimera-like solutions where two elements are synchronized, whereas the third is desynchronized. Moreover, synchronous solutions were found to coexist with stable chimera solutions with a constant phase difference between the oscillators.

Illuminating gravitational waves: A concordant picture of photons from a neutron star merger.

Merging neutron stars offer an excellent laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of an electromagnetic counterpart (EM170817) with gravitational waves (GW170817) detected from merging neutron stars. By synthesizing a panchromatic data set, we demonstrate that merging neutron stars are a long-sought production site forging heavy elements by r-process nucleosynthesis. The weak gamma rays seen in EM170817 are dissimilar to classical short gamma-ray bursts with ultrarelativistic jets. Instead, we suggest that breakout of a wide-angle, mildly relativistic cocoon engulfing the jet explains the low-luminosity gamma rays, the high-luminosity ultraviolet-optical-infrared, and the delayed radio and x-ray emission. We posit that all neutron star mergers may lead to a wide-angle cocoon breakout, sometimes accompanied by a successful jet and sometimes by a choked jet.

Evolution of angiosperms via modulation of antagonisms.

The controversies concerning the evolutionary mechanisms of flowering plants continue unabated in spite of the current trends toward the analysis of macromolecular data and of the growing body of distributional micromolecular data. The usual narrative approach to this latter effort is here replaced by a novel technique, quantitative phytochemistry. An evolutionary outline emerges and reveals modulation of antagonisms as the fundamental mechanism of angiosperm evolutionary ecology. Origin or operation of many systems can be rationalized analogously. It is concluded that the impact of opposing features possesses universal relevance.

Biodiversity: modelling angiosperms as networks.

In the neotropics, one of the last biological frontiers, the major ecological concern should not involve local strategies, but global effects often responsible for irreparable damage. For a holistic approach, angiosperms are ideal model systems dominating most land areas of the present world in an astonishing variety of form and function. Recognition of biogeographical patterns requires new methodologies and entails several questions, such as their nature, dynamics and mechanism. Demographical patterns of families, modelled via species dominance, reveal the existence of South American angiosperm networks converging at the central Brazilian plateau. Biodiversity of habitats, measured via taxonomic uniqueness, reveal higher creative power at this point of convergence than in more peripheral regions. Compositional affinities of habitats, measured via bioconnectivity, reveal the decisive role of ecotones in the exchange or redistribution of information, energy and organisms among the ecosystems. Forming dynamic boundaries, ecotones generate and relay evolutionary novelty, and integrate all neotropical ecosystems into a single vegetation net. Connectivity in such plant webs may depend on mycorrhizal links. If sufficiently general such means of metabolic transfer will require revision of the chemical composition of many plants.

Effects of lignoids on a hematophagous bug, Rhodnius prolixus: feeding, ecdysis and diuresis.

The effects of lignoids on feeding, ecdysis and diuresis in fourth-instar larvae of Rhodnius prolixus (Hemiptera) were investigated. Up to 100 microg/ml burchellin, podophyllotoxin, pinoresinol, sesamin, licarin A, or nordihydroguaiaretic acid (NDGA) in the diet did not induce antifeedant effects. Pinoresinol and NDGA significantly inhibited ecdysis. In experiments in vivo, burchellin and podophyllotoxin reduced the production of urine after feeding. 5-Hydroxytryptamine (5-HT), a diuretic hormone, partially counteracted this effect of burchellin. In experiments in vitro, using isolated Malpighian tubules, (i) burchellin reduced diuretic hormone levels in the hemolymph but not the amount of diuretic hormone stored in the thoracic ganglionic masses (including axons), (ii) burchellin decreased the volume of urine secreted by isolated Malpighian tubules, and (iii) 5-HT could not overcome the effect of burchellin upon the Malpighian tubules. We conclude that burchellin interfered with the release, but not with the production of diuretic hormone by the thoracic ganglionic mass or induced an antidiuretic hormone and directly affected the Malpighian tubules.

Ethnopharmacology versus chemosystematics in the search for biologically active principles in plants.

The chemicals to which Brazilian angiosperms owe their use in the preparation of arrow poisons, hallucinogens, fish poisons, drugs, stimulants, spices, perfumes and pigments are correlated with the systematic position of the species in which they occur. Most compounds are produced either by the primitive Magnoliidae (sensu Cronquist) or by the advanced Asteridae. The Rosidae-Dilleniidae, precisely the group of subclasses of widest distribution over the country, have heretofore yielded relatively few useful compounds. This fact can be rationalized by the presence in their species of massive quantities of gallo- and ellagitannins, general defences which make the presence of specific alleochemics superfluous. The natural occurrence of specific biologically active compounds is thus ecologically and systematically conditioned and it should be possible to build a system capable of predicting the existence and the nature of useful chemicals in plant taxa.

Chemical studies on medicinal Myristicaceae from Amazonia.

Drugs from Myristicaceae species are used in the Amazon region as hallucinogens and arrow poisons, as well as for the healing of infected wounds. The former effects were attributed by Schultes and Holmstedt to tryptamines and carbolines. The latter activity is now tentatively ascribed to pterocarpans and neolignans. This, and a proposal that the red colour of the bark resins may be due to oxidative dimers of flavans, are based on a review of the chemistry of Amazonian Myristicaceae.

Ocotea quixos, American cinnamon.

Among the three South American Lauraceae with cinnamon odours, Ocotea quixos Lam. is distinguished with the richest historical legacy. Cinnamaldehyde, its odoriferous principle, occurs besides o-methoxycinnamaldehyde, cinnamic acid and methyl cinnamate in the fruit calyx. In contradistinction, 1-nitro-2-phenylethane is responsible for the cinnamon odour of bark and leaves of Aniba canelilla (H..B.K.) Mez and Ocotea pretiosa (Nees) Mez.

Effects of some lignans and neolignans on the development and excretion of Rhodnius prolixus.

The effects of six lignans and neolignans as inhibitors of ecdysis and on the water balance in fourth-instar larvae of Rhodnius prolixus were studied by oral, topical and continuous contact treatments. The main results may be summarised as follows: (i) burchellin, pinoresinol, sesamin, licarin A and nordihydroguaiaretic acid (NDGA) did not cause feeding inhibition at doses of 100 micrograms/ml blood; podophyllotoxin had no antifeedant effect but caused a high moulting inhibition and significant toxicity when applied either orally or topically; (ii) the highest ecdysis inhibitory effects were observed with pinoresinol and NDGA when applied orally at a dose of 100 micrograms/ml (58% and 50% of moulting inhibition, respectively); burchellin inhibited 30% of the moulting at this concentration; (iii) by topical treatment none of the compounds presented any influence on the moulting cycle; and (iv) podophyllotoxin and burchellin significantly reduced the excretion of the insect in 24 h; the other compounds had no effect on excretion. The implications of these findings in relation to the pertinent biological events in R. prolixus are discussed.

The rational search for natural neolignans.

A rational method of search for natural neolignans of desired structures is outlined. This involves consultation of a collection of chemical profiles of plant families. The profiles are assembled considering the biosynthetic class (in the present case lignoids), subclass (neolignans), structural types (neolignan skeletal) and relative frequency of substitutional derivatives belonging to each type (known compounds). The method is of course applicable to any class of natural products. Its use in the case of neolignans is here selected as an example in view of the recently discovered antagonism towards PAF of kadsurenone, a representative of this subclass of phytochemicals. Application of the chemical profiles to phylogenetic studies is illustrated.

Chemosystematics of the gnetatae and the chemical evolution of seed plants1.

A survey of the secondary metabolites reported for EPHEDRA, WELWITSCHIA and GNETUM documents a far-reaching chemical similarity of these genera with the angiosperms. However, the different substitution patterns of the phenolics do not support a close phylogenetic link between the two groups. The most significant chemical difference between the Gnetatae and the angiosperms seems to be the widespread use of protective devices against oxidation such as O-methylation and formation of Schiff bases which are so frequent in angiosperms and nearly absent from the Gnetatae and other gymnosperms.

Comparative ethnopharmacology: a rational method for the search of bioactive compounds in plants.

In the present preliminary communication on comparative ethnopharmacology a limited universe of data extracted from the Journal of Ethnopharmacology (vols. 1-25) was used for the construction of ethnopharmacological profiles of ten families of dicotyledons. Intraprofile analysis suggested the main uses of plant species (indicated by the maximal citation frequencies), as opposed to the spurious ones (represented by base line fluctuations), to possess a solid chemotaxonomic basis. Interprofile analysis via correlation of ethnopharmacological distances and morphological (evolutionary) distances among the same plant families suggested comparative ethnopharmacology to possess also a phylogenetic (chemosystematic) basis. This result establishes comparative ethnopharmacology as a novel and potentially useful scientific discipline.

Medicinal products: regulation of biosynthesis in space and time.

We live in a "Demon-Haunted World". Human health care requires the ever increasing resistance of pathogens to be confronted by a correspondingly fast rate of discovery of novel antibiotics. One of the possible strategies towards this objective involves the rational localization of bioactive phytochemicals. The conceptual basis of the method consists in the surprisingly little known gearings of natural products with morphology, ecology and evolution of their plant source, i. e. an introspection into the general mechanisms of nature.

XVIII: Eperudiendiol, Glycerides and Neolignans from Fruits of Osteophloeum platyspermum1.

The fruits of OSTEOPHLOEUM PLATYSPERMUM (Myristicaceae) contain sitosterol, eperu-8(20),13-dien-3alpha,15-diol, glyceryl laurodimyristate, glyceryl 1,3-lauromyristate and five neolignans: dihydroguaiaretic acid, hydroxyotobain, hydroxyoxootobain, guaiacin and otobaphenol.

Phytoalexin induction in rubiaceae.

Phytoalexin responses were measured by modified drop-diffusate and facilitated diffusion techniques after fungal inoculation of leaves of 32 Rubiaceae species from Brazilian forest and savanna. Such responses presented a trend similar to that previously observed for a broad sample of dicotyledonous plants and are more frequently positive for the more primitive (or slower growing) trees than for the advanced (or faster growing) herbs. Fifteen of these species analyzed during a one-year period showed that positive phytoalexin responses are stronger for the rainy (and hotter) than for the dry (and cooler) season. Species that contain relatively large quantities of phenolics gave invariably negative responses. Positive responses are not necessarily associated with the appearance of new substances within leaf tissue and are thus caused by inhibitins rather than by phytoalexins. These results are discussed recognizing that the tested plants are subject to the multifarious influences of their natural environment and of a possible conjugate-caused compartmentation of plant metabolites.

(2E,4E)-N-isobutyl-9-piperonyl-nona-2,4-dienoic amide from Ottonia anisum.

Roots and stems of Ottonia anisum contain besides 1-butyl-3,4-methylenedioxybenzene and piperovatine, the novel (2E,4E)-N-isobutyl-9-piperonyl-nona-2,4-dienoic amide.