Extreme Ultraviolet Reflective Grating Characterization and Simulationsfor the Aspera SmallSat Mission

The Aspera SmallSat mission is designed to detect and map the warm-hot gaseous component of the halos of nearby galaxies through long-slit spectroscopy of the ionized O VI emission line (103.2 nm) for the first time. The Aspera Rowland circle type spectrograph uses a toroidal grating coated with a multilayer film consisting of aluminum, lithium fluoride, and magnesium fluoride capping to optimize reflectivity in the extreme ultraviolet (EUV) waveband from 103 to 104nm. We discuss the grating characterization test setup at the University of Arizona (UA), which will validate the multilayer coating and grating efficiency in a UV vacuum chamber. We also simulate the reflectivity of the multilayer thin film coating using IMD IDL software to compare simulated results with measured reflectivity. Additionally, non-sequential ray trace simulations and 3D CAD modeling are used for verification of the test setup. Finally, the implications of the differences between the measured and simulated reflectivity and grating efficiencies are considered, including impact to the mission

SIIOS in Alaska: Testing an "In-Vault" Option for a Europa Lander Seismometer Experiment

The icy moons of Europa and Enceladus are thought to have global subsurface oceans in contact with mineral-rich silicate interiors, likely providing the three ingredients needed for life as we know it: liquid water, essential chemicals, and a source of energy. The possibility of life forming in their subsurface oceans relies in part on transfer of oxidants from the irradiated ice surface to the sheltered ocean below. Constraining the mechanisms and location of material exchange between the ice surface, the ice shell, and the subsurface ocean, however, is not possible without knowledge of ice thickness and liquid water depths. In a future lander-based experiment seismic measurements will be a key geophysical tool for obtaining this critical knowledge. The Seismometer to Investigate Ice and Ocean Structure (SIIOS) field-tests flight-ready technologies and develops the analytical methods necessary to make a seismic study of Europa and Enceladus a reality. We have been performing small-array seismology with a flight-candidate sensor in analog environments that exploit passive sources. Determining the depth to a subsurface ocean and any intermediate bodies of water is a priority for Ocean Worlds missions as it allows assessment of the habitability of these worlds and provides vital information for evaluating the spacecraft technologies required to access their oceans

Overwintering individuals of the Arctic krill Thysanoessa inermis appear tolerant to short-term exposure to low pH conditions

Areas of the Arctic Ocean are already experiencing seasonal variation in low pH/elevated pCO2 and are predicted to be the most affected by future ocean acidification (OA). Krill play a fundamental ecological role within Arctic ecosystems, serving as a vital link in the transfer of energy from phytoplankton to higher trophic levels. However, little is known of the chemical habitat occupied by Arctic invertebrate species, and of their responses to changes in seawater pH. Therefore, understanding krill’s responses to low pH conditions has important implications for the prediction of how Arctic marine communities may respond to future ocean change. Here, we present natural seawater carbonate chemistry conditions found in the late polar winter (April) in Kongsfjord, Svalbard (79°North) as well as the response of the Arctic krill, Thysanoessa inermis, exposed to a range of low pH conditions. Standard metabolic rate (measured as oxygen consumption) and energy metabolism markers (incl. adenosine triphosphate (ATP) and l-lactate) of T. inermis were examined. We show that after a 7 days experiment with T. inermis, no significant effects of low pH on MO2, ATP and l-lactate were observed. Additionally, we report carbonate chemistry from within Kongsfjord, which showed that the more stratified inner fjord had lower total alkalinity, higher dissolved inorganic carbon, pCO2 and lower pH than the well-mixed outer fjord. Consequently, our results suggest that overwintering individuals of T. inermis may possess sufficient ability to tolerate short-term low pH conditions due to their migratory behaviour, which exposes T. inermis to the naturally varying carbonate chemistry observed within Kongsfjord, potentially allowing T. inermis to tolerate future OA scenarios

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

Contrasting responses to salinity and future ocean acidification in arctic populations of the amphipod Gammarus setosus.

From PubMed via Jisc Publications RouterHistory: received 2020-06-12, revised 2020-09-10, accepted 2020-10-06Publication status: aheadofprintClimate change is leading to alterations in salinity and carbonate chemistry in arctic/sub-arctic marine ecosystems. We examined three nominal populations of the circumpolar arctic/subarctic amphipod, Gammarus setosus, along a salinity gradient in the Kongsfjorden-Krossfjorden area of Svalbard. Field and laboratory experiments assessed physiological (haemolymph osmolality and gill Na /K -ATPase activity, NKA) and energetic responses (metabolic rates, MO , and Cellular Energy Allocation, CEA). In the field, all populations had similar osmregulatory capacities and MO , but lower-salinity populations had lower CEA. Reduced salinity (S = 23) and elevated pCO (~1000 μatm) in the laboratory for one month increased gill NKA activities and reduced CEA in all populations, but increased MO in the higher-salinity population. Elevated pCO did not interact with salinity and had no effect on NKA activities or CEA, but reduced MO in all populations. Reduced CEA in lower-rather than higher-salinity populations may have longer term effects on other energy demanding processes (growth and reproduction). [Abstract copyright: Copyright © 2020 Elsevier Ltd. All rights reserved.

The Deployment of the Seismometer to Investigate Ice and Ocean Structure (SIIOS) in Northwest Greenland: An experiment to study icy ocean world seismic deployments

In anticipation of future spacecraft missions to icy ocean worlds, the Seismometer to Investigate Ice and Ocean Structure (SIIOS) was funded by NASA to prepare for seismologic investigations of these worlds. During the summer of 2018, the SIIOS team deployed a seismic experiment on the Greenland Ice Sheet situated approximately 80 km north of Qaanaaq, Greenland. The deployment included one Trillium 120 s Posthole (TPH) broadband seismometer, thirteen Silicon Audio flight-candidate seismometers, five Sercel L28 4.5 Hz geophones, and one HTI 60-min hydrophone. Seismometers were buried 1 m deep in the firn in a cross-shaped array centered on a co-located TPH, hydrophone, and Silicon Audio instrument. One part of the array consisted of Silicon Audio and Sercel Geophones situated 1 m from the center of the array in the ordinal directions. A second set of four Silicon Audio instruments situated 1 km from the center of the array, in the cardinal directions. A mock-lander spacecraft was placed at the array center and instrumented with four Silicon Audio seismometers. We performed an active-source experiment and a passive-listening experiment that lasted for approximately 12 days. The active-source experiment consisted of 9-12 sledgehammer strikes to an aluminum plate at ten separate locations up to 100 m from the array center. The passive experiment recorded the ice-sheet ambient background noise, as well as local and regional events. Both datasets will be used to quantify differences in spacecraft instrumentation deployment strategies and for evaluating science capabilities for single-station and small-aperture seismic arrays in future geophysical missions. Our initial results indicate that the flight-candidate seismometer performs comparably to the TPH at frequencies above 0.1 Hz and that instruments coupled to the mock-lander perform comparably to ground-based instrumentation in the frequency band of 0.01-10 Hz. For future icy ocean world missions, a deck-coupled seismometer would perform similarly to a ground-based deployment.NASA PSTAR Grant #80NSSC17K0229 and NASA NESSF # 80NSSC18K126