The theoretical foundation of 3-D Alfvén resonances : time-dependent solutions

Both authors were funded in part by STFC (through Consolidated Grant ST/N000609/1) and The Leverhulme Trust (through Research Grant RPG-2016-071).We present results from a 3-D numerical simulation which investigates the coupling of fast and Alfvén magnetohydrodynamic (MHD) waves in a nonuniform dipole equilibrium. This represents the time-dependent extension of the normal mode (∝ exp(−iωt)) analysis of Wright and Elsden (2016), and provides a theoretical basis for understanding 3-D Alfvén resonances. Wright and Elsden (2016) show that these are fundamentally different to resonances in 1D and 2D. We demonstrate the temporal behavior of the Alfvén resonance, which is formed within the "Resonant Zone"; a channel of the domain where a family of solutions exists such that the natural Alfvén frequency matches the fast-mode frequency. At early times, phase mixing leads to the production of prominent ridges in the energy density, whose shape is determined by the Alfvén speed profile and the chosen background magnetic field geometry. These off resonant ridges decay in time, leaving only a main 3-D resonant sheet in the steady state. We show that the width of the 3-D resonance in time and in space can be accurately estimated by adapting previous analytical estimates from 1-D theory. We further provide an analytical estimate for the resonance amplitude in 3-D, based upon extending 2-D theory.Publisher PDFPeer reviewe

The effect of fast normal mode structure and magnetopause forcing on FLRs in a 3‐D waveguide

T. Elsden and A. N. Wright were funded by the Leverhulme Trust through Research grant RPG-2016-071. A. N. Wright was also funded by STFC through Consolidated grant ST/N000609/1.This paper investigates the excitation of waveguide modes in a nonuniform dipole equilibrium and, further, their coupling to field line resonances (FLRs). Waveguide modes are fast compressional ultralow frequency (ULF) waves, whose structure depends upon the magnetospheric equilibrium and the solar wind driving conditions. Using magnetohydrodynamic simulations, we consider how the structure of the excited waveguide mode is affected by various forms of magnetopause driving. We find that the waveguide supports a set of normal modes that are determined by the equilibrium. However, the particular normal modes that are excited are determined by the structure of the magnetopause driver. A full understanding of the spatial structure of the normal modes is required in order to predict where coupling to FLRs will occur. We show that symmetric pressure driving about the noon meridian can excite normal modes which remain around to drive resonances for longer than antisymmetric driving. Further, the critical quantity in terms of efficient coupling is the magnetic pressure gradient aligned with the resonance.Publisher PDFPeer reviewe

Microbial−mammalian cometabolites dominate the age-associated urinary metabolic phenotype in Taiwanese and American populations

Understanding the metabolic processes associated with aging is key to developing effective management and treatment strategies for age-related diseases. We investigated the metabolic profiles associated with age in a Taiwanese and an American population. 1H NMR spectral profiles were generated for urine specimens collected from the Taiwanese Social Environment and Biomarkers of Aging Study (SEBAS; n = 857; age 54–91 years) and the Mid-Life in the USA study (MIDUS II; n = 1148; age 35–86 years). Multivariate and univariate linear projection methods revealed some common age-related characteristics in urinary metabolite profiles in the American and Taiwanese populations, as well as some distinctive features. In both cases, two metabolites—4-cresyl sulfate (4CS) and phenylacetylglutamine (PAG)—were positively associated with age. In addition, creatine and β-hydroxy-β-methylbutyrate (HMB) were negatively correlated with age in both populations (p < 4 × 10–6). These age-associated gradients in creatine and HMB reflect decreasing muscle mass with age. The systematic increase in PAG and 4CS was confirmed using ultraperformance liquid chromatography–mass spectrometry (UPLC–MS). Both are products of concerted microbial–mammalian host cometabolism and indicate an age-related association with the balance of host–microbiome metabolism

Data Work in a Knowledge-Broker Organization: How Cross-Organizational Data Maintenance shapes Human Data Interactions.

The term Human-Data Interaction (HDI) conceptualizes the growing importance of understanding how people need and desire to use and interact with data. Previous HDI cases have mainly focused on the interface between personal health data and the healthcare sector. This paper argues that it is relevant to consider HDI at an organisational level and examines how HDI can look in such a context, where data and data maintenance are core assets and activities. We report on initial findings of a study of a knowledge-broker organisation, where we follow how data are produced, shared, and maintained in a cross-organisational context. We discuss similarities and differences of HDI aroundpersonal health data and cross-organisational data maintenance. We propose to extend the notion of HDI to include the complexity of cross-organisational data work

Properties of magnetohydrodynamic normal modes in the Earth’s magnetosphere

Funding: MDH was supported by NASA 80NSSC19K0127, 80NSSC19K0907, 80NSSC21K1683, 80NSSC21K1677, 80NSSC23K0903, and NSF AGS-2307204. KT was supported by NASA 80NSSC19K0259 and 80NSSC21K0453. MOA was supported by a UKRI (STFC / EPSRC) Stephen Hawking Fellowship EP/T01735X/1. The research of A.W. was funded in part by Science and Technology Facilities Council (STFC) grant ST/W001195/1 (UK). T.E. was funded in part by a Leverhulme Early Career Fellowship ECF-2019-155 (UK). AA and XZ were supported by NASA 80NSSC21K0729 and 80NSSC23K0108. We acknowledge support from ISSI Bern through ISSI International Team projects 483 “The Identification And Classification Of 3D Alfven Resonances” and 546 “Magnetohydrodynamic Surface Waves at Earth’s Magnetosphere (and Beyond).” We acknowledge NASA contract NAS5-02099.The Earth's magnetosphere supports a variety of Magnetohydrodynamic (MHD) normal modes with Ultra Low Frequencies (ULF) including standing Alfvén waves and cavity/waveguide modes. Their amplitudes and frequencies depend in part on the properties of the magnetosphere (size of cavity, wave speed distribution). In this work, we use ∼13 years of Time History of Events and Macroscale Interactions during Substorms satellite magnetic field observations, combined with linearized MHD numerical simulations, to examine the properties of MHD normal modes in the region L > 5 and for frequencies 5 depend on both the magnetopause location and the location of peaks in the radial Alfvén speed profile. Finally, we discuss how these results might be used to better model radiation belt electron dynamics related to ULF waves.PostprintPeer reviewe

Gut-Tracking as Cultivation

Contemporary self-tracking devices take forms that reflect particular cultures of self-tracking that emphasize clinical perspectives and numerical precision. In this pictorial, we explore alternative forms to speculate on other possible self-tracking cultures. We present how we involved experts on the relationship between the gut and the brain to inspire a design brief for an alternative gut tracking device. This led to the design of Loupe and Lightbox, which together operate to externalize gut biota for closer examination, aesthetic appreciation, and reflection on the self. The device represents an example of self-tracking as cultivation—building a longer-term relationship with the self as something to be nurtured, tended to, and cared about

Removal as a Method: A Fourth Wave HCI Approach to Understanding the Experience of Self-Tracking

This paper offers first-steps guidance towards the development of a methodology that embodies theoretical proposals for a fourth-wave, 'entanglement' approach to HCI. We propose the removal of technologies and the documenting of their absence as a method. Removal disrupts habitual relationships with our everyday technologies, revealing otherwise hidden knowledges. Removal as a method exemplifies that "you don't know what you've got till it's gone". We apply removal to the case of menstrual cycle tracking in two ways: literally through two autoethnographies, and hypothetically through semi-structured interviews. We show how this method especially facilitates emotional, embodied and cultural knowledge of the lived experience of self-tracking and we unpack some opportunities, implications and limitations in its use. Finally, we present how this method might be adopted by others and propose cases in which removal as a method might be applicable to study of a wider range of technologies beyond self-tracking

Electron paramagnetic resonance and other properties of hydrogenases isolated from Desulfovibrio vulgaris (strain Hildenborough) and Megasphaera elsdenii

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65872/1/j.1432-1033.1983.tb07727.x.pd

Redox properties of the iron-sulfur clusters in activated Fe-hydrogenase from Desulfovibrio vulgaris (Hildenborough)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65750/1/j.1432-1033.1992.tb17261.x.pd

Personal Informatics, Self-Insight, and Behavior Change: A Critical Review of Current Literature

Personal Informatics (PI) systems allow users to collect and review personally relevant information. The purpose commonly envisioned for these systems is that they provide users with actionable, data-driven self-insight to help them change their behavioral patterns for the better. Here, we review relevant theory as well as empirical evidence for this ‘Self-Improvement Hypothesis’. From a corpus of 6568 only 24 studies met the selection criteria of being a peer-reviewed empirical study reporting on actionable, data-driven insights from PI data, using a ‘clean’ PI system with no other intervention techniques (e.g. additional coaching) on a non-clinical population. First results are promising—many of the selected articles report users gaining actionable insights—but we do note a number of methodological issues that make these results difficult to interpret. We conclude that more work is needed to investigate the Self-Improvement Hypothesis and provide a set of recommendations for future work