The kinetic Alfvén-like nature of turbulent fluctuations in the Earth's magnetosheath: MMS measurement of the electron Alfvén ratio

The Magnetospheric MultiScale (MMS) mission is used to investigate turbulent fluctuations in the Earth's magnetosheath. The unique combination of multiple spacecraft and high time resolution plasma and electromagnetic field data provided by MMS makes it an ideal mission to study the nature of turbulence and energy conversion. The multiple spacecraft allow the determination of the wavevector directions and plasma frame frequencies of the fluctuations. Moreover, the particle velocities allow the determination of the ion and electron Alfvén ratios, giving an additional diagnostic to reveal the nature of the turbulent fluctuations. Finally, the currents (determined from plasma moments) and the three-dimensional electric field measurements allow the determination of a scale-dependent energy conversion rate. The results reveal that the fluctuations predominantly have kinetic Alfvén wave-like properties at wavenumbers near kpi~1 (where ρi is the ion gyroradius) and that Landau damping is an important pathway for converting energy

Possible coexistence of kinetic Alfvén and ion Bernstein modes in sub-ion scale compressive turbulence in the solar wind

We investigate compressive turbulence at sub-ion scales with measurements from the Magnetospheric MultiScale Mission. The tetrahedral configuration and high time resolution density data obtained by calibrating spacecraft potential allow an investigation of the turbulent density fluctuations in the solar wind and their three-dimensional structure in the sub-ion range. The wave-vector associated with the highest energy density at each spacecraft frequency is obtained by application of the multipoint signal resonator technique to the four-point density data. The fluctuations show a strong wave-vector anisotropy k⊥ k� where the parallel and perpendicular symbols are with respect to the mean magnetic-field direction. The plasma frame frequencies show two populations, one below the proton cyclotron frequency ω<ci consistent with kinetic Alfvén wave (KAW) turbulence. The second component has higher frequencies ω>ci consistent with ion Bernstein wave turbulence. Alternatively, these fluctuations may constitute KAWs that have undergone multiple wave-wave interactions, causing a broadening in the plasma frame frequencies. The scale-dependent kurtosis in this wavevector region shows a reduction in intermittency at the small scales which can also be explained by the presence of wave activity. Our results suggest that small-scale turbulence exhibits linear-wave properties of kinetic Alfvén and possibly ion-Bernstein (magnetosonic) waves. Based on our results, we speculate that these waves may play a role in describing the observed reduction in intermittency at sub-ion scales

Magnetic Field Reconstruction for a Realistic Multi-Point, Multi-Scale Spacecraft Observatory

Future in situ space plasma investigations will likely involve spatially distributed observatories comprised of multiple spacecraft, beyond the four and five spacecraft configurations currently in operation. Inferring the magnetic field structure across the observatory, and not simply at the observation points, is a necessary step towards characterizing fundamental plasma processes using these unique multi-point, multi-scale data sets. We propose improvements upon the classic first-order reconstruction method, as well as a second-order method, utilizing magnetometer measurements from a realistic nine-spacecraft observatory. The improved first-order method, which averages over select ensembles of four spacecraft, reconstructs the magnetic field associated with simple current sheets and numerical simulations of turbulence accurately over larger volumes compared to second-order methods or first-order methods using a single regular tetrahedron. Using this averaging method on data sets with fewer than nine measurement points, the volume of accurate reconstruction compared to a known magnetic vector field improves approximately linearly with the number of measurement points

Magnetosheath Jet Occurrence Rate in Relation to CMEs and SIRs.

Magnetosheath jets constitute a significant coupling effect between the solar wind (SW) and the magnetosphere of the Earth. In order to investigate the effects and forecasting of these jets, we present the first-ever statistical study of the jet production during large-scale SW structures like coronal mass ejections (CMEs), stream interaction regions (SIRs) and high speed streams (HSSs). Magnetosheath data from Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft between January 2008 and December 2020 serve as measurement source for jet detection. Two different jet definitions were used to rule out statistical biases induced by our jet detection method. For the CME and SIR + HSS lists, we used lists provided by literature and expanded on incomplete lists using OMNI data to cover the time range of May 1996 to December 2020. We find that the number and total time of observed jets decrease when CME-sheaths hit the Earth. The number of jets is lower throughout the passing of the CME-magnetic ejecta (ME) and recovers quickly afterward. On the other hand, the number of jets increases during SIR and HSS phases. We discuss a few possibilities to explain these statistical results

The ECOUTER methodology for stakeholder engagement in translational research

Because no single person or group holds knowledge about all aspects of research, mechanisms are needed to support knowledge exchange and engagement. Expertise in the research setting necessarily includes scientific and methodological expertise, but also expertise gained through the experience of participating in research and/or being a recipient of research outcomes (as a patient or member of the public). Engagement is, by its nature, reciprocal and relational: the process of engaging research participants, patients, citizens and others (the many ‘publics’ of engagement) brings them closer to the research but also brings the research closer to them. When translating research into practice, engaging the public and other stakeholders is explicitly intended to make the outcomes of translation relevant to its constituency of users

Prevalence of Bleeding and Thrombosis in Critically Ill Patients with Chronic Liver Disease

INTRODUCTION:  Hemorrhage and venous thromboembolism (VTE) are recognized complications of chronic liver disease (CLD), but their prevalence and risk factors in critically ill patients are uncertain. PATIENTS AND METHODS:  We studied a retrospective cohort of patients with CLD nonelectively admitted to a specialist intensive care unit (ICU) determining the prevalence and timing of major bleeding and VTE (early, present on admission/diagnosed within 48 hours; later, diagnosed >48 hours post-ICU admission). Associations with baseline clinical and laboratory characteristics, multiorgan failure (MOF), blood product administration, and mortality were explored. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression. RESULTS:  Of 623 patients with median age 52, bleeding (>48 hours after admission) occurred in 87 (14%) patients. Bleeding was associated with greater illness severity and increased mortality. Gastrointestinal bleeding accounted for 72% of events, secondary to portal hypertension in >90%. Procedure-related bleeding was uncommon. VTE occurred in 125 (20%) patients: early VTE in 80 (13%) and involving the portal vein in 85%. Later VTE affected 45 (7.2%) patients. Hepatocellular carcinoma (HCC) and nonalcoholic liver disease were independently associated with early VTE (OR: 2.79, 95% CI: 1.5-5.2 and OR: 2.32, 95% CI: 1.4-3.9, respectively), and HCC, sepsis, and cryoprecipitate use with late VTE (OR: 2.45, 95% CI: 1.11-5.43; OR: 2.26, 95% CI: 1.2-4.3; and OR: 2.60, 95% CI: 1.3-5.1). CONCLUSION:  VTE was prevalent on admission to critical care and less commonly developed later. Bleeding was associated with MOF and increased mortality. Severe MOF was not associated with an increased rate of VTE which was linked with HCC, and specific etiologies of CLD

Ion-scale kinetic Alfvén turbulence: MMS measurements of the Alfvén ratio in the magnetosheath

Turbulence in the Earth's magnetosheath at ion kinetic scales is investigated with the magnetospheric multiscale spacecraft. Several possibilities in the wave paradigm have been invoked to explain plasma turbulence at ion kinetic scales such as kinetic Alfvén, slow, or magnetosonic waves. To differentiate between these different plasma waves is a challenging task, especially since some waves, in particular, kinetic slow waves and kinetic Alfvén waves, share some properties making the possibility to distinguishing between them very difficult. Using the excellent time resolution data set provided from both the fluxgate magnetometer and the Fast Plasma Instrument, the ratio of trace velocity fluctuations to the magnetic fluctuations (in Alfvén units), which is termed the Alfvén ratio, can be calculated down to ion kinetic scales. Comparison of the measured Alfvén ratio is performed with respect to the expectation from two‐fluid magnetohydrodynamic theory for the kinetic slow wave and kinetic Alfvén wave. Moreover, the plasma data also allow normalized fluctuation amplitudes of density and magnetic field to be compared differentiating between magnetosonic‐like and kinetic Alfvén‐like turbulence. Using these two different ratios, we can rule out that the fluctuations at ion scales are dominated by magnetosonic‐like fluctuations or kinetic slow‐like fluctuations and show that they are consistent with kinetic Alfvén‐like fluctuations. This suggests that in the wave paradigm, heating in the direction of the parallel magnetic field is predominantly by the Landau damping of the kinetic Alfvén wave

Magnetosheath jet occurrence rate in relation to CMEs and SIRs

Magnetosheath jets constitute a significant coupling effect between the solar wind (SW) and the magnetosphere of the Earth. In order to investigate the effects and forecasting of these jets, we present the first-ever statistical study of the jet production during large-scale SW structures like coronal mass ejections (CMEs), stream interaction regions (SIRs) and high speed streams (HSSs). Magnetosheath data from Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft between January 2008 and December 2020 serve as measurement source for jet detection. Two different jet definitions were used to rule out statistical biases induced by our jet detection method. For the CME and SIR + HSS lists, we used lists provided by literature and expanded on incomplete lists using OMNI data to cover the time range of May 1996 to December 2020. We find that the number and total time of observed jets decrease when CME-sheaths hit the Earth. The number of jets is lower throughout the passing of the CME-magnetic ejecta (ME) and recovers quickly afterward. On the other hand, the number of jets increases during SIR and HSS phases. We discuss a few possibilities to explain these statistical results

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability