Measuring the Shock Stage of Asteroid Regolith Grains by Electron Back-Scattered Diffraction

We have been analyzing Itokawa samples in order to definitively establish the degree of shock experienced by the regolith of asteroid Itokawa, and to devise a bridge between shock determinations by standard light optical petrography, crystal structures as determined by electron and X-ray diffraction. These techniques would then be available for samples returned from other asteroid regoliths

Measuring Shock Stage of ltokawa Regolith Grains by Electron Back-Scattered Diffraction and Synchrotron X-Ray Diffraction

We have been analyzing Itokawa samples in order to definitively establish the degree of shock experienced by the regolith of asteroid Itokawa, and to devise a bridge between shock determinations by standard light optical petrography, crystal structures as determined by electron and X-ray diffraction techniques. We are making measurements of olivine crystal structures and using these to elucidate critical regolith impact processes. We use electron back-scattered diffraction (EBSD) and synchrotron X-ray diffraction (SXRD). We are comparing the Itokawa samples to L and LL chondrite meteorites chosen to span the shock scale experienced by Itokawa, specifically Chainpur (LL3.4, Shock Stage 1), Semarkona (LL3.00, S2), Kilabo (LL6, S3), NWA100 (L6, S4) and Chelyabinsk (LL5, S4). In SXRD we measure the line broadening of olivine reflections as a measure of shock stage. In this presentation we concentrate on the EBSD work. We employed JSC's Supra 55 variable pressure FEG-SEM and Bruker EBSD system. We are not seeking actual strain values, but rather indirect strain-related measurements such as extent of intra-grain lattice rotation, and determining whether shock state "standards" (meteorite samples of accepted shock state, and appropriate small grain size) show strain measurements that may be statistically differentiated, using a sampling of particles (number and size range) typical of asteroid regoliths. Using our system we determined that a column pressure of 9 Pa and no C-coating on the sample was optimal. We varied camera exposure time and gain to optimize mapping performance, concluding that 320x240 pattern pixilation, frame averaging of 3, 15 kV, and low extractor voltage yielded an acceptable balance of hit rate (>90%), speed (11 fps) and map quality using an exposure time of 30 ms (gain 650). We found that there was no strong effect of step size on Grain Orientation Spread (GOS) and Grain Reference Orientation Deviation angle (GROD-a) distribution; there was some effect on grain average Kernel Average Misorientation (KAM) (reduced with smaller step size for the same grain), as expected. We monitored GOS, Maximum Orientation Spread (MOS) and GROD-a differences between whole olivine grains and sub-sampled areas, and found that there were significant differences between the whole grain dataset and subsets, as well as between subsets, likely due to sampling-related "noise". Also, in general (and logically) whole grains exhibit greater degrees of cumulative lattice rotation. Sampling size affects the apparent strain character of the grain, at least as measured by GOS, MOS and GROD-a. There were differences in the distribution frequencies of GOS and MOS between shock stages, and in plots of MOS and GOS vs. grain diameter. These results are generally consistent with those reported this year. However, it is unknown whether the differences between samples of different shock states exceeds the clustering of these values to the extent that shock stage determinations can still be made with confidence. We are investigating this by examination of meteorites with higher shock stage 4 to 5. Our research will improve our understanding of how small, primitive solar system bodies formed and evolved, and improve understanding of the processes that determine the history and future of habitability of environments on other solar system bodies. The results will directly enrich the ongoing asteroid and comet exploration missions by NASA and JAXA, and broaden our understanding of the origin and evolution of small bodies in the early solar system, and elucidate the nature of asteroid and comet regolith

Simple standing test without furosemide is useful in the diagnosis of primary aldosteronism

Abstract Primary aldosteronism (PA) is a well-known cause of secondary hypertension. We have long performed the simple standing test in patients with PA. On the other hand, there are few reports on the usefulness of the simple standing test in PA. This study is a single-center, retrospective, observational study. A total of 173 patients with hypertension or adrenal tumor admitted to Kawasaki Medical School were included. Eighty patients who met the exclusion criteria were excluded, and 31 patients without PA (non-PA), 26 patients with unilateral PA, and 36 patients with bilateral PA were included in the study. The simple standing test was performed after 120 min of standing or sitting followed, and the aldosterone/renin ratio (ARR) and percentage of increase plasma aldosterone concentration (%increase of PAC) was calculated. The mean ARR in the simple standing test in unilateral PA (1143 (528–2200)) and bilateral PA subjects (521 (374–765)) were significantly higher compared to non-PA subjects (152 (102–240)) (p < 0.0001, p = 0.0013, respectively). The percentage increase of PAC after standing loading was significantly lower in unilateral PA subjects (110 (96–140)) compared to non-PA subjects (187 (155–244)) (p = 0.0003), with no difference between non-PA and bilateral PA subjects (p = 0.99). The cutoff value of the ARR in the simple standing test for diagnosis of PA in this study was 364 (AUC = 0.948, sensitivity = 83.8%, specificity = 93.5%, false positive rate = 3.7%, false negative rate = 25.6%, p < 0.001), which was not inferior to the diagnostic performance of the captopril loading test. The diagnostic performance of the simple standing test for PA was not inferior to that of the captopril loading test. The percentage increase of PAC in unilateral PA subjects was significantly lower compared to bilateral PA subjects. These results demonstrate the usefulness of the simple standing test, which can be performed simultaneously with general screening tests of PA