The Properties of Lion Roars and Electron Dynamics in Mirror Mode Waves Observed by the Magnetospheric MultiScale Mission

Mirror mode waves are ubiquitous in the Earth's magnetosheath, in particular behind the quasi‐perpendicular shock. Embedded in these nonlinear structures, intense lion roars are often observed. Lion roars are characterized by whistler wave packets at a frequency ∼100 Hz, which are thought to be generated in the magnetic field minima. In this study, we make use of the high time resolution instruments on board the Magnetospheric MultiScale mission to investigate these waves and the associated electron dynamics in the quasi‐perpendicular magnetosheath on 22 January 2016. We show that despite a core electron parallel anisotropy, lion roars can be generated locally in the range 0.05–0.2fce by the perpendicular anisotropy of electrons in a particular energy range. We also show that intense lion roars can be observed up to higher frequencies due to the sharp nonlinear peaks of the signal, which appear as sharp spikes in the dynamic spectra. As a result, a high sampling rate is needed to estimate correctly their amplitude, and the latter might have been underestimated in previous studies using lower time resolution instruments. We also present for the first‐time 3‐D high time resolution electron velocity distribution functions in mirror modes. We demonstrate that the dynamics of electrons trapped in the mirror mode structures are consistent with the Kivelson and Southwood (1996) model. However, these electrons can also interact with the embedded lion roars: first signatures of electron quasi‐linear pitch angle diffusion and possible signatures of nonlinear interaction with high‐amplitude wave packets are presented. These processes can lead to electron untrapping from mirror modes

Sonographic evaluation of the shoulder in asymptomatic elderly subjects with diabetes

<p>Abstract</p> <p>Background</p> <p>The prevalence of rotator cuff tears increases with age and several studies have shown that diabetes is associated with symptomatic shoulder pathologies. Aim of our research was to evaluate the prevalence of shoulder lesions in a population of asymptomatic elderly subjects, normal and with non insulin - dependent diabetes mellitus.</p> <p>Methods</p> <p>The study was performed on 48 subjects with diabetes and 32 controls (mean age: 71.5 ± 4.8 and 70.7 ± 4.5, respectively), who did not complain shoulder pain or dysfunction. An ultrasound examination was performed on both shoulders according to a standard protocol, utilizing multiplanar scans.</p> <p>Results</p> <p>Tendons thickness was greater in diabetics than in controls (Supraspinatus Tendon: 6.2 ± 0.09 mm <it>vs </it>5.2 ± 0.7 mm, p < 0.001; Biceps Tendon: 4 ± 0.8 mm <it>vs </it>3.2 ± 0.4 mm, p < 0.001). Sonographic appearances of degenerative features in the rotator cuff and biceps were more frequently observed in diabetics (Supraspinatus Tendon: 42.7% <it>vs </it>20.3%, p < 0.003; Biceps Tendon: 27% <it>vs </it>7.8%, p < 0.002).</p> <p>Subjects with diabetes exhibited more tears in the Supraspinatus Tendon (Minor tears: 15 (15.8%) <it>vs </it>2 (3.1%), p < 0.03; Major tears: 15 (15.8%) <it>vs </it>5 (7.8%), p = ns), but not in the long head of Biceps. More effusions in subacromial bursa were observed in diabetics (23.9% <it>vs </it>10.9%, p < 0.03) as well as tenosynovitis in biceps tendon (33.3% <it>vs </it>10.9%, p < 0.001).</p> <p>In both groups, pathological findings were prevalent on the dominant side, but no difference related to duration of diabetes was found.</p> <p>Conclusions</p> <p>Our results suggest that age - related rotator cuff tendon degenerative changes are more common in diabetics.</p> <p>Ultrasound is an useful tool for discovering in pre - symptomatic stages the subjects that may undergo shoulder symptomatic pathologies.</p

The coloniality of infrastructure: Engineering, landscape and modernity in Recife

Geographical scholarship has, since the late 1990s, shown how infrastructure was central to the making of urban modernity and the metabolic transformation of socio-natures. Meanwhile, the work of Latin American scholars including Aníbal Quijano and Maria Lugones has focussed attention on the imbrications between modernity and coloniality, in particular through the international racial division of labour. Moving between these ideas, I argue that there is intellectual and political ground to be gained by specifically accounting for the coloniality of infrastructure, in both its material and epistemic dimensions. I ground the analysis in the history of Recife, Northeast of Brazil, analyzing the role of British engineering in the production of the city's landscape and infrastructure, and address the epistemic dimensions of the coloniality of infrastructural by exploring infrastructural spectacle in 1920s Recife. Finally, I explore how the coloniality of infrastructure directs our attention to race, labour and finance

Lower-hybrid drift waves and electromagnetic electron space-phase holes associated with dipolarization fronts and field-aligned currents observed by the Magnetospheric Multiscale mission during a substorm

We analyse two ion scale dipolarization fronts associated with field-aligned currents detected by the Magnetospheric Multiscale mission during a large substorm on August 10, 2016. The first event corresponds to a fast dawnward flow with an anti-parallel current and could be generated by the wake of a previous fast earthward flow. It is associated with intense lower-hybrid drift waves detected at the front and propagating dawnward with a perpendicular phase speed close to the electric drift and the ion thermal velocity. The second event corresponds to a flow reversal: from southwward/dawnward to northward/duskward associated with a parallel current consistent with a brief expansion of the plasma sheet before the front crossing, and with a smaller lower-hybrid drift wave activity. Electromagnetic electron phase-space holes are detected near these low-frequency drift waves during both events. The drift waves could accelerate electrons parallel to the magnetic field and produce the parallel electron drift needed to generate the electron holes. Yet, we cannot rule out the possibility that the drift waves are produced by the anti-parallel current associated with the fast flows, leaving the source for the electron holes unexplained