The Variation of Resonating Magnetospheric Field Lines With Changing Geomagnetic and Solar Wind Conditions

Standing ultralow frequency waves redistribute energy and momentum around the Earth's magnetosphere. The eigenfrequencies of these standing waves can be measured by applying the cross-phase technique to ground magnetometer data. To make a detection, the flux tubes in the vicinity of the magnetometers must all be driven at their local eigenfrequencies by a source with a sufficient frequency width. Therefore, successful measurement of the local eigenfrequencies indicates that a broadband source is exciting the flux tubes. We have analyzed 10 years of magnetometer data with an automated cross-phase algorithm and used correlations with the OMNI data set to understand under what conditions broadband excitation occurs and how the conditions affect the eigenfrequency values. This is the largest such survey of its kind to date. We found that lower eigenfrequencies at higher latitudes (L>5) and higher eigenfrequencies at lower latitudes (L<4) were excited under different conditions. It was also possible to directly compare the first and third harmonics at midlatitudes. The lower eigenfrequencies were excited during more disturbed conditions, and we suggest that these harmonics are driven by solar wind pressure pulses or the Kelvin-Helmholtz instability at the magnetopause. The higher eigenfrequencies were excited when the magnetosphere was relatively quiet, and we suggest that the cause was waves generated upstream of the Earth's bow shock. The eigenfrequencies were observed to decrease in the middle magnetosphere during disturbed intervals. This is because the intensification of the ring current weakens the magnetic field. Variations in magnetic local time and latitude were also investigated

The Edge Effect in High-Throughput Proteomics: A Cautionary Tale

In order for mass spectrometry to continue to grow as a platform for high-throughput clinical and translational research, careful consideration must be given to quality control by ensuring that the assay performs reproducibly and accurately and precisely. In particular, the throughput required for large cohort clinical validation in biomarker discovery and diagnostic screening has driven the growth of multiplexed targeted liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) assays paired with sample preparation and analysis in multiwell plates. However, large scale MS-based proteomics studies are often plagued by batch effects: sources of technical variation in the data, which can arise from a diverse array of sources such as sample preparation batches, different reagent lots, or indeed MS signal drift. These batch effects can confound the detection of true signal differences, resulting in incorrect conclusions being drawn about significant biological effects or lack thereof. Here, we present an intraplate batch effect termed the edge effect arising from temperature gradients in multiwell plates, commonly reported in preclinical cell culture studies but not yet reported in a clinical proteomics setting. We present methods herein to ameliorate the phenomenon including proper assessment of heating techniques for multiwell plates and incorporation of surrogate standards, which can normalize for intraplate variation

Examination of human osteoarchaeological remains as a feasible source of polar and apolar metabolites to study past conditions

Metabolomics is a modern tool that aids in our understanding of the molecular changes in organisms. Archaeological science is a branch of archaeology that explores different archaeological materials using modern analytical tools. Human osteoarchaeological material are a frequent finding in archaeological contexts and have the potential to offer information about previous human populations, which can be illuminating about our current condition. Using a set of samples comprising different skeletal elements and bone structures, here we explore for the first time the possibility of extracting metabolites from osteoarchaeological material. Here, a protocol for extraction and measurement of extracted polar and less-polar/apolar metabolites by ultra-high performance liquid chromatography hyphenated to high resolution mass spectrometry is presented to measure the molecules separated after a reversed phase and hydrophilic interaction liquid chromatography column. Molecular information was obtained, showing that osteoarchaeological material is a viable source of molecular information for metabolomic studies

Modeling the Varying Location of Field Line Resonances During Geomagnetic Storms

Previous observational studies have shown that the natural Alfvén frequencies of geomagnetic field lines vary significantly over the course of a geomagnetic storm, decreasing by up to 50% from their quiet time values outside the plasmasphere. This was recently demonstrated statistically using ground magnetometer observations across 132 geomagnetic storm events (Wharton et al., 2020). This then brings into question where field line resonances (FLRs) will form in storm-time conditions relative to quiet times. With storm-time radiation belt dynamics depending heavily upon wave-particle interactions, understanding how FLR locations change over the course of a storm will have important implications for this area. Using 3D magnetohydrodynamic (MHD) simulations, we investigate how changes in the Alfvén frequency continuum of the Earth's dayside magnetosphere over the course of a geomagnetic storm affect the fast-Alfvén wave coupling. By setting the model Alfvén frequencies consistent with the observations, and permitting a modest change in the plasmapause/magnetopause locations consistent with storm-time behavior, we show that FLR locations can change substantially during storms. The combined effects of higher fast waveguide frequencies and lower Alfvén frequencies during storm main phases, act together to move the FLR locations radially inwards compared to quiet times. FLRs outside of the plasmasphere are moved radially inward by 1.7 Earth radii for the cases considered.Plain Language SummaryGeomagnetic storms are the most energetic events in our Earth's near space environment, causing huge morphological changes over timescales from a few hours to several days. This study considers how such changes affect the propagation of low frequency electromagnetic waves in the space around the Earth dominated by Earth's magnetic field (the magnetosphere). It is important to understand how these waves may vary during geomagnetic storms, due to their interaction with energetic particles which can be hazardous to orbiting spacecraft. Furthermore, from a general physics standpoint, it is of interest to understand how energy is transported throughout the system by such waves. Overall we find that, between the initial and main phases of a storm, there are significant changes in the locations where a particular class of low frequency waves will manifest. The simple broad conclusion from this paper is that storms change the morphology of Earth's magnetosphere, which then significantly changes the properties of the waves in the system.</div

Proenkephalin and prognosis in heart failure with preserved ejection fraction: a GREAT network study.

BACKGROUND: Proenkephalin (PENK), a stable endogenous opioid biomarker related to renal function, has prognostic utility in acute and chronic heart failure. We investigated the prognostic utility of PENK in heart failure with preserved ejection fraction (HFpEF), and its relationship to renal function, Body Mass Index (BMI), and imaging measures of diastolic dysfunction. METHODS: In this multicentre study, PENK was measured in 522 HFpEF patients (ejection fraction > 50%, 253 male, mean age 76.13 ± 10.73 years) and compared to 47 age and sex-matched controls. The primary endpoint was 2-years composite of all-cause mortality and/or heart failure rehospitalisation (HF). A subset (n = 163) received detailed imaging studies. RESULTS: PENK levels were raised in HFpEF (median [interquartile range] 88.9 [62.1-132.0]) compared to normal controls (56.3 [47.9-70.5]). PENK was correlated to urea, eGFR, Body Mass Index and E/e' (rs 0.635, - 0.741, - 0.275, 0.476, respectively, p < 0.0005). During 2 years follow-up 144 patients died and 220 had death/HF endpoints. Multivariable Cox regression models showed PENK independently predicted 2 year death/HF [hazard ratio (for 1 SD increment of log-transformed biomarker) HR 1.45 [95% CI 1.12-1.88, p = 0.005]], even after adjustment for troponin (HR 1.59 [1.14-2.20, p = 0.006]), and Body Mass Index (HR 1.63 [1.13-2.33, p = 0.009]). PENK showed no interaction with ejection fraction status for prediction of poor outcomes. Net reclassification analyses showed PENK significantly improved classification of death/HF outcomes for multivariable models containing natriuretic peptide, troponin and Body Mass Index (p < 0.05 for all). CONCLUSIONS: In HFpEF, PENK levels are related to BMI, and measures of diastolic dysfunction and are prognostic for all-cause mortality and heart failure rehospitalisation