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Auroral kilometric radiation (AKR) is a terrestrial radio emission excited by the same accelerated electrons which excite auroral emissions. Although it is well correlated with auroral and geomagnetic activity, the coupling timescales between AKR and different magnetospheric or ionospheric regions have yet to be determined. Estimation of these coupling timescales is non-trivial as a result of complex, non-linear processes which rarely occur in isolation. In this study, the mutual information between AKR intensity and different geomagnetic indices is used to assess the correlation between variables. Indices are shifted to different temporal lags relative to AKR intensity, and the lag at which the variables have the most shared information is found. This lag is interpreted as the coupling timescale. The AKR source region receives the effects of a shared driver before the auroral ionosphere. Conversely, the polar ionosphere reacts to a shared driver before the AKR source region. Bow shock interplanetary magnetic field BZ is excited about 1 h before AKR enhancements. This work provides quantitatively determined temporal context to the coupling timelines at Earth. The results suggest that there is a sequence of excitation following the onset of a shared driver: first, the polar ionosphere feels the effects, followed by the AKR source region and then the auroral ionosphere.

Jupiter is a source of intense radio emissions in the decametric wavelength range observable from ground (above ∼10 MHz) and from space (down to a few kHz). The strong anisotropy of the Jovian radio sources results in characteristic shapes in the temporal-spectral domain, which can be used to identified the various types of Jovian radio components. The Jupiter Probability Tool provides users with Jovian radio emission observability predictions, depending on the observers location, and the radio emission class. The application can be used for observation planning or data analysis for ground or space observations.

The Saturn Kilometric Radiation (SKR) was observed for the first time during the flyby of Saturn by the Voyager spacecraft in 1980. These radio emissions, in the range of a few kHz to 1 MHz, are emitted by electrons travelling around auroral magnetic field lines. Their study is useful to understand the variability of a magnetosphere and its coupling with the solar wind. Previous studies have shown a strong correlation between the solar wind dynamic pressure and the SKR intensity. However, up to now, the effect of an Interplanetary Coronal Mass Ejection (ICME) has never been examined in detail, due to the lack of SKR observations at the time when an ICME can be tracked and its different parts be clearly identified. In this study, we take advantage of a large ICME that reached Saturn mid-November 2014 (Witasse et al., J. Geophys. Res. Space Physics, 2017, 122, 7865–7890). At that time, the Cassini spacecraft was fortunately travelling within the solar wind for a few days, and provided a very accurate timing of the ICME structure. A survey of the Cassini data for the same period indicated a significant increase in the SKR emissions, showing a good correlation after the passage of the ICME shock with a delay of ∼13 h and after the magnetic cloud passage with a delay of 25–42 h.

The Europlanet-2020 programme, which ended on Aug 31st, 2019, included an activity called VESPA (Virtual European Solar and Planetary Access), which focused on adapting Virtual Observatory (VO) techniques to handle Planetary Science data. This paper describes some aspects of VESPA at the end of this 4-years development phase and at the onset of the newly selected Europlanet-2024 programme starting in 2020. The main objectives of VESPA are to facilitate searches both in big archives and in small databases, to enable data analysis by providing simple data access and online visualization functions, and to allow research teams to publish derived data in an interoperable environment as easily as possible. VESPA encompasses a wide scope, including surfaces, atmospheres, magnetospheres and planetary plasmas, small bodies, heliophysics, exoplanets, and spectroscopy in solid phase. This system relies in particular on standards and tools developed for the Astronomy VO (IVOA) and extends them where required to handle specificities of Solar System studies. It also aims at making the VO compatible with tools and protocols developed in different contexts, for instance GIS for planetary surfaces, or time series tools for plasma-related measurements. An essential part of the activity is to publish a significant amount of high-quality data in this system, with a focus on derived products resulting from data analysis or simulations.

Narrowband emission (NB) is observed at Saturn centered near 5 kHz and 20 kHz and harmonics. This emission appears similar in many ways to Jovian kilometric narrowband emission observed at higher frequencies, and therefore may have a similar source mechanism. Source regions of NB near 20 kHz are believed to be located near density gradients in the inner magnetosphere and the emission appears to be correlated with the occurrence of large neutral plasma clouds observed in the Saturn magnetotail. In this work we present the results of a growth rate analysis of NB emission (~20 kHz) near or within a probable source region. This is made possible by the sampling of in-situ wave and particle data. The results indicate waves are likely to be generated by the mode-conversion of directly generated Z-mode emission to O-mode near a density gradient. When the local hybrid frequency is close n fce (n is an integer and fce is the electron cyclotron frequency) with n=4, 5 or 6 in our case, electromagnetic Z-mode and weak ordinary (O-mode) emission can be directly generated by the cyclotron maser instability.

Previous studies have shown that the occurrence probability of Saturn Kilometric Radiation (SKR) appears to be influenced by the local time of Titan. Using a more extensive set of data than the original study, we confirm the correlation of higher occurrence probability of SKR when Titan is located near local midnight. In addition, the direction finding capability of the Cassini Radio Plasma Wave instrument (RPWS) is used to determine if this radio emission emanates from particular source regions. We find that most source regions of SKR are located in the mid-morning sector of local time even when Titan is located near midnight. However, some emission does appear to have a source in the Saturnian nightside, consistent with electron precipitation from field lines that have recently mapped to near Titan.

Voyager spacecraft measurements of Saturn kilometric radiation (SKR) identified two features of these radio emissions: that they pulse at a period close to the planetary rotation period, and that the emitted intensity is correlated with the solar wind dynamic pressure (Desch and Kaiser, 1981; Desch, 1982; Desch and Rucker, 1983). In this study the inter-relation between the intensity and the pulsing of the SKR is analysed using Cassini spacecraft measurements of the interplanetary medium and SKR over the interval encompassing Cassini's approach to Saturn, and the first extended orbit. Cassini Plasma Spectrometer ion data were only available for a subset of the dates of interest, so the interplanetary conditions were studied primarily using the near-continuously available magnetic field data, augmented by the ion moment data when available. Intense SKR bursts were identified when solar wind compressions arrived at Saturn. The intensity of subsequent emissions detected by Cassini during the compression intervals was variable, sometimes remaining intense for several planetary rotations, sometimes dimming and rarely disappearing. The timings of the initial intense SKR peaks were sometimes independent of the long-term pulsing behaviour identified in the SKR data. Overall, however, the pulsing of the SKR peaks during the disturbed intervals was not significantly altered relative to that during non-compression intervals.

The external control of Saturn kilometric radiation (SKR) by the solar wind has been investigated in the frame of the Linear Prediction Theory (LPT). The LPT establishes a linear filter function on the basis of correlations between input signals, i.e. time profiles for solar wind parameters, and output signals, i.e. time profiles for SKR intensity. Three different experiments onboard the Cassini spacecraft (RPWS, MAG and CAPS) yield appropriate data sets for compiling the various input and output signals. The time period investigated ranges from DOY 202 to 326, 2004 and is only limited due to limited availability of CAPS plasma data for the solar wind. During this time Cassini was positioned mainly on the morning side on its orbit around Saturn at low southern latitudes. Four basic solar wind quantities have been found to exert a clear influence on the SKR intensity profile. These quantities are: the solar wind bulk velocity, the solar wind ram pressure, the magnetic field strength of the interplanetary magnetic field (IMF) and the y-component of the IMF. All four inputs exhibit nearly the same level of efficiency for the linear prediction indicating that all four inputs are possible drivers for triggering SKR. Furthermore, they act at completely different lag times ranging from ~13 h for the ram pressure to ~52 h for the bulk velocity. The lag time for the magnetic field strength is usually beyond ~40 h and the lag time for the y-component of the magnetic field is located around 30 h. Considering that all four solar wind quantities are interrelated in a corotating interaction region, only the influence of the ram pressure seems to be of reasonable relevance. An increase in ram pressure causes a substantial compression of Saturn's magnetosphere leading to tail collapse, injection of hot plasma from the tail into the outer magnetosphere and finally to an intensification of auroral dynamics and SKR emission. So, after the onset of magnetospheric compression at least ~1.2 rotations of the planet elapse until intensified SKR emission is visible in a Cassini-RPWS dynamic spectrum.

Saturn Electrostatic discharges (SED) are sporadic broadband impulsive radio bursts associated with lightning in Saturnian atmosphere. After 25 years of space investigations in 2006 the first successful observations of SED on the UTR-2 radio telescope were carried out [1]. Since2007 along-term program of ED search and study in the Solar system has started. As a part of this program the unique observations with high time resolution were taken in 2010. New possibilities of UTR-2 radio telescope allowed to provide a long-period observations and study with high temporal resolution. This article presents the results of SED study in a wide range of time scales: from seconds to mi­croseconds. For the first time there were obtained a low frequency spectrum of SED. We calculated flux densities of individual bursts at the maximum achievable time resolu­tion. Flux densities of most intensive bursts reach 4200 Jy.

Background: Disconnected consciousness describes a state in which subjective experience (i.e., consciousness) becomes isolated from the external world. It appears frequently during sleep or sedation, when subjective experiences remain vivid but are unaffected by external stimuli. Traditional methods of differentiating connected and disconnected consciousness, such as relying on behavioral responsiveness or on post-anesthesia reports, have demonstrated limited accuracy: unresponsiveness has been shown to not necessarily equate to unconsciousness and amnesic effects of anesthesia and sleep can impair explicit recollection of events occurred during sleep/sedation. Due to these methodological challenges, our understanding of the neural mechanisms underlying sensory disconnection remains limited., Methods: To overcome these methodological challenges, we employ a distinctive strategy by combining a serial awakening paradigm with auditory stimulation during mild propofol sedation. While under sedation, participants are systematically exposed to auditory stimuli and questioned about their subjective experience (to assess consciousness) and their awareness of the sounds (to evaluate connectedness/disconnectedness from the environment). The data collected through interviews are used to categorize participants into connected and disconnected consciousness states. This method circumvents the requirement for responsiveness in assessing consciousness and mitigates amnesic effects of anesthesia as participants are questioned while still under sedation. Functional MRI data are concurrently collected to investigate cerebral activity patterns during connected and disconnected states, to elucidate sensory disconnection neural gating mechanisms. We examine whether this gating mechanism resides at the thalamic level or results from disruptions in information propagation to higher cortices. Furthermore, we explore the potential role of slow-wave activity (SWA) in inducing disconnected consciousness by quantifying high-frequency BOLD oscillations, a known correlate of slow-wave activity., Discussion: This study represents a notable advancement in the investigation of sensory disconnection. The serial awakening paradigm effectively mitigates amnesic effects by collecting reports immediately after regaining responsiveness, while still under sedation. Ultimately, this research holds the potential to understand how sensory gating is achieved at the neural level. These biomarkers might be relevant for the development of sensitive anesthesia monitoring to avoid intraoperative connected consciousness and for the assessment of patients suffering from pathologically reduced consciousness., Clinical Trial Registration: European Union Drug Regulating Authorities Clinical Trials Database (EudraCT), identifier 2020-003524-17., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Cecconi, Montupil, Mortaheb, Panda, Sanders, Phillips, Alnagger, Remacle, Defresne, Boly, Bahri, Lamalle, Laureys, Gosseries, Bonhomme and Annen.)

The study of the brain's dynamical activity is opening a window to help the clinical assessment of patients with disorders of consciousness. For example, glucose uptake and the dysfunctional spread of naturalistic and synthetic stimuli has proven useful to characterize hampered consciousness. However, understanding of the mechanisms behind loss of consciousness following brain injury is still missing. Here, we study the propagation of endogenous and in-silico exogenous perturbations in patients with disorders of consciousness, based upon directed and causal interactions estimated from resting-state fMRI data, fitted to a linear model of activity propagation. We found that patients with disorders of consciousness suffer decreased capacity for neural propagation and responsiveness to events, and that this can be related to severe reduction of glucose metabolism as measured with [ 18 F]FDG-PET. In particular, we show that loss of consciousness is related to the malfunctioning of two neural circuits: the posterior cortical regions failing to convey information, in conjunction with reduced broadcasting of information from subcortical, temporal, parietal and frontal regions. These results shed light on the mechanisms behind disorders of consciousness, triangulating network function with basic measures of brain integrity and behavior., (© 2023 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.)

We study 10 years (1995-2004 inclusive) of auroral kilometric radiation (AKR) radio emission data from the Wind spacecraft to examine the link between AKR and terrestrial substorms. We use substorm lists based on parameters including ground magnetometer signatures and geosynchronous particle injections as a basis for superposed epoch analyses of the AKR data. The results for each list show a similar, clear response of the AKR power around substorm onset. For nearly all event lists, the average response shows that the AKR power begins to increase around 20 min prior to expansion phase onset, as defined by the respective lists. The analysis of the spectral parameters of AKR bursts show that this increase in power is due to an extension of the source region to higher altitudes, which also precedes expansion phase onset by 20 min. Our observations show that the minimum frequency channel that observes AKR at this time, on average, is 60 kHz. AKR visibility is highly sensitive to observing spacecraft location, and the biggest radio response to substorm onset is seen in the 21:00-03:00 hr local time sector., (© 2022. The Authors.)

A new radio component namely Saturn Anomalous Myriametric Radiation (SAM) is reported. A total of 193 SAM events have been identified by using all the Cassini Saturn orbital data. SAM emissions are L-O mode radio emission and occasionally accompanied by a first harmonic in R-X mode. SAM's intensities decrease with increasing distance from Saturn, suggesting a source near Saturn. SAM has a typical central frequency near 13 kHz, a bandwidth greater than 8 kHz and usually drifts in frequency over time. SAM's duration can extend to near 11 hr and even longer. These features distinguish SAM from the regular narrowband emissions observed in the nearby frequency range, hence the name anomalous. The high occurrence rate of SAM after low frequency extensions of Saturn Kilometric Radiation and the SAM cases observed during compressions of Saturn's magnetosphere suggest a special connection to solar wind dynamics and magnetospheric conditions at Saturn., (© 2022. The Authors.)

Background: Assessing consciousness in other subjects, particularly in non-verbal and behaviourally disabled subjects (e.g., patients with disorders of consciousness), is notoriously challenging but increasingly urgent. The high rate of misdiagnosis among disorders of consciousness raises the need for new perspectives in order to inspire new technical and clinical approaches., Main Body: We take as a starting point a recently introduced list of operational indicators of consciousness that facilitates its recognition in challenging cases like non-human animals and Artificial Intelligence to explore their relevance to disorders of consciousness and their potential ethical impact on the diagnosis and healthcare of relevant patients. Indicators of consciousness mean particular capacities that can be deduced from observing the behaviour or cognitive performance of the subject in question (or from neural correlates of such performance) and that do not define a hard threshold in deciding about the presence of consciousness, but can be used to infer a graded measure based on the consistency amongst the different indicators. The indicators of consciousness under consideration offer a potential useful strategy for identifying and assessing residual consciousness in patients with disorders of consciousness, setting the theoretical stage for an operationalization and quantification of relevant brain activity., Conclusions: Our heuristic analysis supports the conclusion that the application of the identified indicators of consciousness to its disorders will likely inspire new strategies for assessing three very urgent issues: the misdiagnosis of disorders of consciousness; the need for a gold standard in detecting consciousness and diagnosing its disorders; and the need for a refined taxonomy of disorders of consciousness., (© 2022. The Author(s).)

The reflection-by-sheath mechanism of 5 kHz narrowband emissions (NB) at Saturn is confirmed by Cassini observations during several crossings of the magnetopause, which show that the 5 kHz NB can be prevented from escaping Saturn's magnetosphere. The L-O mode 5 kHz NB remained visible in areas of low plasma density but disappeared in regions of high plasma density. In three cases, NB disappeared immediately after the crossings of Saturn's magnetopause. A possible reflected NB event observed near the magnetosheath is discussed. This mechanism can help explain the 5 kHz NB observed at low latitudes outside the Enceladus plasma torus and their upper frequency limit variations. This mechanism significantly improves the current understanding of the 5 kHz NB., (© 2022. The Authors.)

Objective: Brain-injured patients who are unresponsive at the bedside (ie, vegetative state/unresponsive wakefulness syndrome - VS/UWS) may present brain activity similar to patients in minimally conscious state (MCS). This peculiar condition has been termed "non-behavioural MCS" or "MCS*". In the present study we aimed to investigate the proportion and underlying brain characteristics of patients in MCS*., Methods: Brain 18 F-fluorodeoxyglucose Positron Emission Tomography (FDG-PET) was acquired on 135 brain-injured patients diagnosed in prolonged VS/UWS (n = 48) or MCS (n = 87). From an existing database, relative metabolic preservation in the fronto-parietal network (measured with standardized uptake value) was visually inspected by three experts. Patients with hypometabolism of the fronto-parietal network were labelled "VS/UWS", while its (partial) preservation either confirmed the behavioural diagnosis of "MCS" or, in absence of behavioural signs of consciousness, suggested a diagnosis of "MCS*". Clinical outcome at 1-year follow-up, functional connectivity, grey matter atrophy, and regional brain metabolic patterns were investigated in the three groups (VS/UWS, MCS* and MCS)., Results: 67% of behavioural VS/UWS presented a partial preservation of brain metabolism (ie, MCS*). Compared to VS/UWS patients, MCS* patients demonstrated a better outcome, global functional connectivity and grey matter preservation more compatible with the diagnosis of MCS. MCS* patients presented lower brain metabolism mostly in the posterior brain regions compared to MCS patients., Interpretation: MCS* is a frequent phenomenon that is associated with better outcome and better brain preservation than the diagnosis of VS/UWS. Complementary exams should be provided to all unresponsive patients before taking medical decisions. ANN NEUROL 2021;90:89-100., (© 2021 The Authors. Annals of Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)

Understanding how auroral radio emissions are produced by magnetized bodies requires in situ measurements within their source region. Saturn's kilometric radiation (SKR) has been widely used as a remote proxy of Saturn's magnetosphere. We present wave and plasma measurements from the Cassini spacecraft during its ring-grazing high-inclination orbits, which passed three times through the high-altitude SKR emission region. Northern dawn-side, narrow-banded radio sources were encountered at frequencies of 10 to 20 kilohertz, within regions of upward currents mapping to the ultraviolet auroral oval. The kilometric waves were produced on the extraordinary mode by the cyclotron maser instability from 6- to 12-kilo-electron volt electron beams and radiated quasi-perpendicularly to the auroral magnetic field lines. The SKR low-frequency sources appear to be strongly controlled by time-variable magnetospheric electron densities., (Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

A thiophene-based donor-acceptor phenothiazine dye has been functionalized with a peripheral glucose unit (PTZ-GLU) to bust its affinity to water and enhance dye-sensitized photogeneration of hydrogen. Compared to the corresponding alkyl derivative (PTZ-ALK), as well as the common hydrophilic triethylene glycol substitution (PTZ-TEG), the sugar derivative shows a lower contact angle; PTZ-GLU performed twice more efficient than PTZ-TEG in the photogeneration of hydrogen in terms of evolved gas and turnover number.

Dibranched donor-(π-acceptor)2 dyes, where phenothiazine is the donor core, cyanoacrylic acid is the acceptor/anchoring group, and π is represented by mono- and poly-cyclic simple and fused thiophene derivatives, were tested as photosensitizers in the photocatalytic production of H2 , in combination with a Pt/TiO2 catalyst. The optical and electrochemical properties of the dyes were investigated, showing that careful design of the thiophene-based π spacer afforded enhanced optical properties. In the H2 production over 20 h, the new thiophene-based sensitizers revealed improved stability after longer irradiation times and enhanced performances, in terms of H2 production rates and light-to-fuel efficiencies, after an initial activation period, which were for the first time associated with enhanced stability under photocatalytic production of H2 and the absence of critical dye degradation., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Rational development of efficient photocatalytic systems for hydrogen production requires understanding the catalytic mechanism and detailed information about the structure of intermediates in the catalytic cycle. We demonstrate how time-resolved X-ray absorption spectroscopy in the microsecond time range can be used to identify such intermediates and to determine their local geometric structure. This method was used to obtain the solution structure of the Co(I) intermediate of cobaloxime, which is a non-noble metal catalyst for solar hydrogen production from water. Distances between cobalt and the nearest ligands including two solvent molecules and displacement of the cobalt atom out of plane formed by the planar ligands have been determined. Combining in situ X-ray absorption and UV/Vis data, we demonstrate how slight modification of the catalyst structure can lead to the formation of a catalytically inactive Co(I) state under similar conditions. Possible deactivation mechanisms are discussed., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The internal rotation rates of the giant planets can be estimated by cloud motions, but such an approach is not very precise because absolute wind speeds are not known a priori and depend on latitude: periodicities in the radio emissions, thought to be tied to the internal planetary magnetic field, are used instead. Saturn, despite an apparently axisymmetric magnetic field, emits kilometre-wavelength (radio) photons from auroral sources. This emission is modulated at a period initially identified as 10 h 39 min 24 +/- 7 s, and this has been adopted as Saturn's rotation period. Subsequent observations, however, revealed that this period varies by +/-6 min on a timescale of several months to years. Here we report that the kilometric radiation period varies systematically by +/-1% with a characteristic timescale of 20-30 days. Here we show that these fluctuations are correlated with solar wind speed at Saturn, meaning that Saturn's radio clock is controlled, at least in part, by conditions external to the planet's magnetosphere. No correlation is found with the solar wind density, dynamic pressure or magnetic field; the solar wind speed therefore has a special function. We also show that the long-term fluctuations are simply an average of the short-term ones, and therefore the long-term variations are probably also driven by changes in the solar wind.

We report data from the Cassini radio and plasma wave instrument during the approach and first orbit at Saturn. During the approach, radio emissions from Saturn showed that the radio rotation period is now 10 hours 45 minutes 45 +/- 36 seconds, about 6 minutes longer than measured by Voyager in 1980 to 1981. In addition, many intense impulsive radio signals were detected from Saturn lightning during the approach and first orbit. Some of these have been linked to storm systems observed by the Cassini imaging instrument. Within the magnetosphere, whistler-mode auroral hiss emissions were observed near the rings, suggesting that a strong electrodynamic interaction is occurring in or near the rings.

Saturn is a source of intense kilometre-wavelength radio emissions that are believed to be associated with its polar aurorae, and which provide an important remote diagnostic of its magnetospheric activity. Previous observations implied that the radio emission originated in the polar regions, and indicated a strong correlation with solar wind dynamic pressure. The radio source also appeared to be fixed near local noon and at the latitude of the ultraviolet aurora. There have, however, been no observations relating the radio emissions to detailed auroral structures. Here we report measurements of the radio emissions, which, along with high-resolution images of Saturn's ultraviolet auroral emissions, suggest that although there are differences in the global morphology of the aurorae, Saturn's radio emissions exhibit an Earth-like correspondence between bright auroral features and the radio emissions. This demonstrates the universality of the mechanism that results in emissions near the electron cyclotron frequency narrowly beamed at large angles to the magnetic field.