Integrating simultaneous in situ measurements of magnetic field fluctuations, precipitating electrons, and ultraviolet auroral emissions, we find that Alfvénic acceleration mechanisms are responsible ...for Ganymede's auroral footprint tail. Magnetic field perturbations exhibit enhanced Alfvénic activity with Poynting fluxes of ~100 mW/m2. These perturbations are capable of accelerating the observed broadband electrons with precipitating fluxes of ~11 mW/m2, such that Alfvénic power is transferred to electron acceleration with ~10% efficiency. The ultraviolet emissions are consistent with in situ electron measurements, indicating 13 ± 3 mW/m2 of precipitating electron flux. Juno crosses flux tubes with both upward and downward currents connected to the auroral tail exhibiting small‐scale structure. We identify an upward electron conic in the downward current region, possibly due to acceleration by inertial Alfvén waves near the Jovian ionosphere. In concert with in situ observations at Io's footprint tail, these results suggest that Alfvénic acceleration processes are broadly applicable to magnetosphere‐satellite interactions.
Plain Language Summary
Jupiter's moon Ganymede interacts with the planet's rapidly rotating magnetic field, which generates an aurora in the Jovian upper atmosphere. The Juno spacecraft crossed magnetic field lines connected to this aurora. We found that a specific type of wave, similar to a wave produced when a string is plucked, is responsible for accelerating the electrons sustaining this aurora. This type of interaction between a moon and the planet it orbits is likely a common process occurring at other exoplanetary systems.
Key Points
First in situ particles and fields measurements connected to Ganymede's auroral tail are reported
Alfvén wave activity is observed with Poynting fluxes of ~100 mW/m2 capable of accelerating electrons into the atmosphere
Ganymede's footprint tail contains electron populations consistent with Alfvénic acceleration and precipitating energy fluxes of ~11 mW/m2
Though it is well established that neonatal nutrition plays a major role in lifelong offspring health, the mechanisms underpinning this have not been well defined. Early postnatal accelerated growth ...resulting from maternal nutritional status is associated with increased appetite and body weight. Likewise, slow growth correlates with decreased appetite and body weight. Food consumption and food-seeking behaviour are directly modulated by central serotonergic (5-hydroxytryptamine, 5-HT) pathways. This study examined the effect of a rat maternal postnatal low protein (PLP) diet on 5-HT receptor mediated food intake in offspring.
Microarray analyses, in situ hybridization or laser capture microdissection of the ARC followed by RT-PCR were used to identify genes up- or down-regulated in the arcuate nucleus of the hypothalamus (ARC) of 3-month-old male PLP rats. Third ventricle cannulation was used to identify altered sensitivity to serotonin receptor agonists and antagonists with respect to food intake.
Male PLP offspring consumed less food and had lower growth rates up to 3 months of age compared with Control offspring from dams fed a normal diet. In total, 97 genes were upregulated including the 5-HT
receptor (5-HT
R) and 149 downregulated genes in PLP rats compared with Controls. The former obesity medication fenfluramine and the 5-HT receptor agonist 5-Carboxamidotryptamine (5-CT) significantly suppressed food intake in both groups, but the PLP offspring were more sensitive to d-fenfluramine and 5-CT compared with Controls. The effect of 5-CT was antagonized by the 5-HT
R antagonist SB699551. 5-CT also reduced NPY-induced hyperphagia in both Control and PLP rats but was more effective in PLP offspring.
Postnatal low protein programming of growth in rats enhances the central effects of serotonin on appetite by increasing hypothalamic 5-HT
R expression and sensitivity. These findings provide insight into the possible mechanisms through which a maternal low protein diet during lactation programs reduced growth and appetite in offspring.
Abstract
Topological network alignment aims to align two networks node-wise in order to maximize the observed common connection (edge) topology between them. The topological alignment of two ...protein–protein interaction (PPI) networks should thus expose protein pairs with similar interaction partners allowing, for example, the prediction of common Gene Ontology (GO) terms. Unfortunately, no network alignment algorithm based on topology alone has been able to achieve this aim, though those that include sequence similarity have seen some success. We argue that this failure of topology alone is due to the sparsity and incompleteness of the PPI network data of almost all species, which provides the network topology with a small signal-to-noise ratio that is effectively swamped when sequence information is added to the mix. Here we show that the weak signal can be detected using multiple stochastic samples of “good” topological network alignments, which allows us to observe regions of the two networks that are robustly aligned across multiple samples. The resulting network alignment frequency (NAF) strongly correlates with GO-based Resnik semantic similarity and enables the first successful cross-species predictions of GO terms based on topology-only network alignments. Our best predictions have an AUPR of about 0.4, which is competitive with state-of-the-art algorithms, even when there is no observable sequence similarity and no known homology relationship. While our results provide only a “proof of concept” on existing network data, we hypothesize that predicting GO terms from topology-only network alignments will become increasingly practical as the volume and quality of PPI network data increase.
Magnetospheric Multiscale (MMS) observations during an extended crossing of the Earth's dayside magnetopause show evidence of multiple reconnections at the boundary. This crossing occurred when the ...Interplanetary Magnetic Field (IMF) was southward and had a significant BY component. Approximately 2 hr after this crossing, the Twin Rocket Investigation of Cusp Electrodynamics‐2 rockets were launched into the northern hemisphere cusp and observed overlapping cusp ion injections. These overlapping injections are also evidence of multiple reconnections at the magnetopause. Observations more than 2 hr apart do not constitute conjunction between the spacecraft and the rockets. However, the IMF conditions during the magnetopause crossing and the cusp traversal were very similar. Therefore, had the magnetopause crossings and cusp traversals occurred at the same time, the observations would have been similar. Thus, these two events illustrate the link between multiple reconnections at the magnetopause and overlapping cusp ion injections.
Plain Language Summary
Magnetic reconnection is a fundamental process in plasmas that interconnects magnetic field lines on either side of a current layer and converts magnetic energy into particle energy. It is the primary process that interconnects the magnetic field of the Sun with the magnetic field of the Earth at the current layer interface called the magnetopause. Ions and electrons from the solar wind follow these interconnected field lines into the Earth's magnetospheric cusps. Magnetic reconnection at the magnetopause occurs along long lines, called X‐lines. This paper discusses observations at the magnetopause and in the cusp that indicate that there are actually multiple X‐lines at the magnetopause and these multiple X‐lines produce a specific signature in the cusp called overlapping ion injections.
Key Points
Magnetospheric multiscale observations often show evidence of multiple reconnection at the magnetopause
Twin Rocket Investigation of Cusp Electrodynamics‐2 observations of overlapping cusp ion injections are also evidence of multiple reconnections at the magnetopause
There is a strong link between multiple reconnections at the magnetopause and overlapping cusp ion dispersions
Jupiter's satellite auroral footprints are a manifestation of the satellite‐magnetosphere interaction of the Galilean moons. Juno's polar elliptical orbit enables crossing the magnetic flux tubes ...connecting each Galilean moon with their associated auroral emission. Its payload allows measuring the fields and particle population in the flux tubes while remotely sensing their associated auroral emissions. During its thirtieth perijove, Juno crossed the flux tube directly connected to Ganymede's leading footprint spot, a unique event in the entire Juno prime mission. Juno revealed a highly‐structured precipitating electron flux, up to 316 mW/m2, while measuring both a small perturbation in the magnetic field azimuthal component and small Poynting flux with an estimated total downward current of 4.2 ± 1.2 kA. Based on the evolution of the footprint morphology and the field and particle measurements, Juno transited for the first time through a region connected to the transhemispheric electron beam of the Ganymede footprint.
Plain Language Summary
The interaction between Jupiter's corotating plasma torus and the Galilean satellites generates a set of complex magnetospheric processes. One such interaction produces permanent auroral spots around Jupiter's northern and southern poles, known as footprints. For each close flyby, Juno's in situ instruments can measure such interaction. During its thirtieth perijove, Juno crossed the magnetic field lines connecting the interaction region of Ganymede with one of its auroral spots on Jupiter. This study describes and analyzes the set of measurements associated with that unique event.
Key Points
Juno crossed the magnetic flux tube connected to Ganymede auroral footprint and recorded a multi‐instrument set of measurements
Juno measured ∼316 mW/m2 of precipitating electrons while magnetically tied to Ganymede's leading auroral footprint spot
The associated Juno measurements suggest that it transited through a region linked to the transhemispheric electron beam
Jupiter's satellite auroral footprints are a consequence of the interaction between the Jovian magnetic field with co‐rotating iogenic plasma and the Galilean moons. The disturbances created near the ...moons propagate as Alfvén waves along the magnetic field lines. The position of the moons is therefore “Alfvénically” connected to their respective auroral footprint. The angular separation from the instantaneous magnetic footprint can be estimated by the so‐called lead angle. That lead angle varies periodically as a function of orbital longitude, since the time for the Alfvén waves to reach the Jovian ionosphere varies accordingly. Using spectral images of the Main Alfvén Wing auroral spots collected by Juno‐UVS during the first 43 orbits, this work provides the first empirical model of the Io, Europa, and Ganymede equatorial lead angles for the northern and southern hemispheres. Alfvén travel times between the three innermost Galilean moons to Jupiter's northern and southern hemispheres are estimated from the lead angle measurements. We also demonstrate the accuracy of the mapping from the Juno magnetic field reference model (JRM33) at the completion of the prime mission for M‐shells extending to at least 15 RJ. Finally, we shows how the added knowledge of the lead angle can improve the interpretation of the moon‐induced decametric emissions.
Plain Language Summary
The interaction between the Jovian magnetospheric plasma and the Galilean moons gives rise to a complex set of phenomena, including the generation of auroral spots magnetically related to the moons and the generation of radio emissions. The magnetic perturbations local to the moons propagate at a finite speed along the magnetic field lines, and reach the northern and southern Jovian hemispheres where they produce the auroral spots. Studying the position of these auroral spots and how they vary over a complete Jovian rotation provides information about the magnetic mapping, as they map directly to the actual physical positions of the moons. The magnetic field model derived from Juno's prime mission is in good agreement with the observation of the satellite footprints. This paper provides information about how the electromagnetic perturbation resulting from the interaction propagates at a finite speed to create auroral spots, leading to an angular shift between the instantaneously magnetically‐mapped position of the moon and the auroral footprint, a quantity also known as the ”equatorial lead angle”. The present work provides an empirical fit of the equatorial lead angle for Io, Europa, and Ganymede derived from Juno data.
Key Points
Over 1,600 ultraviolet spectral images of the Io, Europa, and Ganymede footprints from Juno are analyzed
Empirical formulae for the Io, Europa, and Ganymede equatorial lead angles derived from Juno data are provided
Alfvén travel time estimates are derived, constraining the Alfvénic interaction at the three innermost Galilean moons
Jupiter's polar auroral region hosts UV auroral emissions that relate to the magnetospheric dynamics from the outer magnetosphere. Juno‐UVS has discovered intriguing features characterized by ...expanding emission circles of UV‐brightness <140 kR. These events are located at the border of the previously defined swirl region, nearby the polar dark region. The features expand into a circular shape up to ∼1,000 km in radius, at expansion velocities from 3.3 ± 1.7 up to 7.7 ± 3.5 km/s, as measured over the four best observed cases. Using color ratio measurements as a proxy for the depth of the recorded features, the mean electron energy responsible for these emissions is 80–160 keV. Events occurring in the outer magnetosphere at distances >100 RJ are likely causing for these features. Dayside magnetopause reconnection and Kelvin‐Helmholtz instabilities resulting from the shear flows near the magnetopause are expected to generate field‐aligned currents that could potentially be the cause of these features.
Key Points
Juno‐UVS discovered expanding auroral emission circles with typical brightness up to 140 kR
The features are located in the auroral swirl region, magnetically mapping to the outer magnetosphere
Their origin would be consistent with dayside reconnection or signatures of Kelvin‐Helmholtz instabilities
The hyperbolic phonon polaritons supported in hexagonal boron nitride (hBN) with long scattering lifetimes are advantageous for applications such as super-resolution imaging via hyperlensing. Yet, ...hyperlens imaging is challenging for distinguishing individual and closely spaced objects and for correlating the complicated hyperlens fields with the structure of an unknown object underneath. Here, we make significant strides to overcome each of these challenges. First, we demonstrate that monoisotopic h11BN provides significant improvements in spatial resolution, experimentally resolving structures as small as 44 nm and those with sub 25 nm spacings at 6.76 μm free-space wavelength. We also present an image reconstruction algorithm that provides a structurally accurate, visual representation of the embedded objects from the complex hyperlens field. Further, we offer additional insights into optimizing hyperlens performance on the basis of material properties, with an eye toward realizing far-field imaging modalities. Thus, our results significantly advance label-free, high-resolution, spectrally selective hyperlens imaging and image reconstruction methodologies.
Snakebite victims are commonly seen in KwaZulu-Natal Hospitals, with only a minority of patients requiring antivenom. This study reviewed antivenom-associated adverse events at our institution, after ...administration of the South African Vaccine Producers (SAVP) polyvalent antivenom.
A retrospective review, over 52 months (January 2016–April 2020), of patients who received antivenom. Demographics, clinical details and clinical course following antivenom administration were analysed.
Emergency department doctors treated 758 snakebites; 156 patients were admitted of which 51 (33%) received antivenom. Indications for antivenom included: neurotoxicity (24%), haemotoxicity (18%) and significant cytotoxicity (58%). Antivenom-associated adverse events occurred in 61% of patients; with 47% developing anaphylaxis requiring adrenaline infusion. There was a higher incidence of anaphylaxis in children (57%) than in adults (40%), p = 0.55. There was no association between antivenom dose and anaphylaxis. No benefit was noted with adrenaline premedication (p = 0.64), nor with the addition of antihistamine or steroid pre-medicants to adrenaline (p = 0.61). Multivariable logistic regression identified age as a predictor for anaphylaxis, but not dose or duration of antivenom and not any particular form of premedication. Intubation was required in 29% of patients developing anaphylaxis. There were no deaths and all patients made full recovery.
Almost half of the patients at Ngwelezana hospital in Kwazulu-Natal receiving the SAVP polyvalent antivenom developed anaphylaxis requiring adrenaline infusion, with children at higher risk. The administration of this antivenom must only be given for valid indications, in a high-care environment by medical personnel ready to manage anaphylactic shock. The addition of antihistamine and corticosteroids to adrenaline for premedication has no added benefit.
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•Snakebites are common in Kwazulu-Natal, South Africa. SAVP Polyvalent antivenom is indicated in 6.7% of snakebite victims.•Adverse reactions to SAVP antivenom occurred in 61% of patients. 47% developed anaphylaxis. Children were more efffected.•SAVP antivenom must only be given for valid indications in a high-care setting by clinicians ready to manage anaphylaxis.
Context. Juno, which studies the Jovian system, continues to expand our knowledge of Jupiter’s magnetosphere and its environment. Thanks to onboard instruments such as Jupiter Energetic Particle ...Detector Instrument (JEDI) and Jovian Auroral Distributions Experiment (JADE), in situ measurements have allowed us to derive a realistic representation of charged particle energy distributions precipitating in the auroral regions. Because of the distance between Juno’s measurement location and the position of impact of the charged particles, where auroral emissions are produced, these energetic distributions of magnetospheric particles are likely to be affected by various phenomena such as wave-particle interactions on their way from Juno to the atmosphere. These processes can accelerate or decelerate the particles, changing their average energies. Hence, the energy distributions of particles measured at Juno’s altitude are likely different from those at auroral altitudes. Aims. In this study we develop a UV emission model, combined with an electron transport model, that allows us to relate the auroral emission spectra of H2 molecules with the energy distribution of impinging electrons. Methods. Thanks to observations of the Jovian aurora by the Ultraviolet Spectrograph (UVS) on board Juno, we determined the characteristic energies of electrons precipitating in auroral regions during perijove 32. We modeled the relationship between color ratio (CR) and the characteristic energy of precipitating electrons. Initially, we considered mono-energetic electron fluxes. In a second step, we considered fluxes governed by a kappa distribution. Results. We derived characteristic energy maps for electrons precipitating in Jupiter’s auroral regions. In comparison with similar previous studies based on Space Telescope Imaging Spectrograph on board Hubble Space Telescope (HST/STIS) observations, we find that modeling the CR with a mono-energetic distribution leads to a systematic underestimation of the average energy of electrons precipitating in the auroral regions by a factor of 3–5. Conclusions. In this study we show that it is possible to derive a more realistic estimate of electron energy flux distributions at auroral altitudes.
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