| 1. |
- Bergman, A. S., et al.
(författare)
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280 GHz Focal Plane Unit Design and Characterization for the SPIDER-2 Suborbital Polarimeter
- 2018
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Ingår i: Journal of Low Temperature Physics. - : Springer Science and Business Media LLC. - 0022-2291 .- 1573-7357. ; 193:5-6, s. 1075-1084
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Tidskriftsartikel (refereegranskat)abstract
- We describe the construction and characterization of the 280 GHz bolometric focal plane units (FPUs) to be deployed on the second flight of the balloon-borne SPIDER instrument. These FPUs are vital to SPIDER's primary science goal of detecting or placing an upper limit on the amplitude of the primordial gravitational wave signature in the cosmic microwave background (CMB) by constraining the B-mode contamination in the CMB from Galactic dust emission. Each 280 GHz focal plane contains a 16 x 16 grid of corrugated silicon feedhorns coupled to an array of aluminum-manganese transition-edge sensor (TES) bolometers fabricated on 150 mm diameter substrates. In total, the three 280 GHz FPUs contain 1530 polarization-sensitive bolometers (765 spatial pixels) optimized for the low loading environment in flight and read out by time-division SQUID multiplexing. In this paper, we describe the mechanical, thermal, and magnetic shielding architecture of the focal planes and present cryogenic measurements which characterize yield and the uniformity of several bolometer parameters. The assembled FPUs have high yields, with one array as high as 95% including defects from wiring and readout. We demonstrate high uniformity in device parameters, finding the median saturation power for each TES array to be similar to 3 pW at 300 mK with a less than 6% variation across each array at 1 sigma. These focal planes will be deployed alongside the 95 and 150 GHz telescopes in the SPIDER-2 instrument, slated to fly from McMurdo Station in Antarctica in December 2018.
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| 2. |
- Akbarian, S, et al.
(författare)
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The PsychENCODE project
- 2015
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Ingår i: Nature neuroscience. - : Springer Science and Business Media LLC. - 1546-1726 .- 1097-6256. ; 18:12, s. 1707-1712
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Gensicke, H., et al.
(författare)
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Intravenous thrombolysis and platelet count
- 2018
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Ingår i: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 0028-3878 .- 1526-632X. ; 90:8
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveTo study the effect of platelet count (PC) on bleeding risk and outcome in stroke patients treated with IV thrombolysis (IVT) and to explore whether withholding IVT in PC < 100 x 10(9)/L is supported.MethodsIn this prospective multicenter, IVT register-based study, we compared PC with symptomatic intracranial hemorrhage (sICH; Second European-Australasian Acute Stroke Study [ECASS II] criteria), poor outcome (modified Rankin Scale score 3-6), and mortality at 3 months. PC was used as a continuous and categorical variable distinguishing thrombocytopenia (<150 x 10(9)/L), thrombocytosis (>450 x 10(9)/L), and normal PC (150-450 x 10(9)/L [reference group]). Moreover, PC < 100 x 10(9)/L was compared to PC 100 x 10(9)/L. Unadjusted and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) from the logistic regression models were calculated.ResultsAmong 7,533 IVT-treated stroke patients, 6,830 (90.7%) had normal PC, 595 (7.9%) had thrombocytopenia, and 108 (1.4%) had thrombocytosis. Decreasing PC (every 10 x 10(9)/L) was associated with increasing risk of sICH (ORadjusted 1.03, 95% CI 1.02-1.05) but decreasing risk of poor outcome (ORadjusted 0.99, 95% CI 0.98-0.99) and mortality (ORadjusted 0.98, 95% CI 0.98-0.99). The risk of sICH was higher in patients with thrombocytopenic than in patients with normal PC (ORadjusted 1.73, 95% CI 1.24-2.43). However, the risk of poor outcome (ORadjusted 0.89, 95% CI 0.39-1.97) and mortality (ORadjusted 1.09, 95% CI 0.83-1.44) did not differ significantly. Thrombocytosis was associated with mortality (ORadjusted 2.02, 95% CI 1.21-3.37). Forty-four (0.3%) patients had PC < 100 x 10(9)/L. Their risks of sICH (ORunadjusted 1.56, 95% CI 0.48-5.07), poor outcome (ORadjusted 1.63, 95% CI 0.82-3.24), and mortality (ORadjusted 1.38, 95% CI 0.64-2.98) did not differ significantly from those of patients with PC 100 x 10(9)/L.ConclusionLower PC was associated with increased risk of sICH, while higher PC indicated increased mortality. Our data suggest that PC modifies outcome and complications in individual patients, while withholding IVT in all patients with PC < 100 x 10(9)/L is challenged.
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| 4. |
- Gualtieri, R., et al.
(författare)
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SPIDER : CMB Polarimetry from the Edge of Space
- 2018
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Ingår i: Journal of Low Temperature Physics. - : Springer Science and Business Media LLC. - 0022-2291 .- 1573-7357. ; 193:5-6, s. 1112-1121
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Tidskriftsartikel (refereegranskat)abstract
- SPIDER is a balloon-borne instrument designed to map the polarization of the millimeter-wave sky at large angular scales. Spider targets the B-mode signature of primordial gravitational waves in the cosmic microwave background (CMB), with a focus on mapping a large sky area with high fidelity at multiple frequencies. SPIDER's first long-duration balloon (LDB) flight in January 2015 deployed a total of 2400 antenna-coupled transition-edge sensors (TESs) at 90 GHz and 150 GHz. In this work we review the design and in-flight performance of the SPIDER instrument, with a particular focus on the measured performance of the detectors and instrument in a space-like loading and radiation environment. SPIDER's second flight in December 2018 will incorporate payload upgrades and new receivers to map the sky at 285 GHz, providing valuable information for cleaning polarized dust emission from CMB maps.
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| 5. |
- Nagy, J. M., et al.
(författare)
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A New Limit on CMB Circular Polarization from SPIDER
- 2017
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 844:2
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Tidskriftsartikel (refereegranskat)abstract
- We present a new upper limit on cosmic microwave background (CMB) circular polarization from the 2015 flight of SPIDER, a balloon-borne telescope designed to search for B-mode linear polarization from cosmic inflation. Although the level of circular polarization in the CMB is predicted to be very small, experimental limits provide a valuable test of the underlying models. By exploiting the nonzero circular-to-linear polarization coupling of the half-wave plate polarization modulators, data from SPIDER's 2015 Antarctic flight provide a constraint on Stokes V at 95 and 150 GHz in the range 33 < l < 307. No other limits exist over this full range of angular scales, and SPIDER improves on the previous limit by several orders of magnitude, providing 95% C.L. constraints on l (l + 1)C-l(VV) /(2 pi) ranging from 141 to 255 mu K-2 at 150 GHz for a thermal CMB spectrum. As linear CMB polarization experiments become increasingly sensitive, the techniques described in this paper can be applied to obtain even stronger constraints on circular polarization.
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| 6. |
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| 7. |
- Kasvayee, Keivan Amiri, 1986-, et al.
(författare)
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Strain localization and crack formation effects on stress-strain response of ductile iron
- 2017
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Ingår i: Materials Science & Engineering. - : Elsevier. - 0921-5093 .- 1873-4936. ; 702, s. 265-271
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Tidskriftsartikel (refereegranskat)abstract
- The strain localization and crack formation in ferritic-pearlitic ductile iron under tension was investigated by in-situ tensile tests. In-situ tensile tests under optical microscope were performed and the onset of the early ferrite-graphite decohesions and micro-cracks inside the matrix were studied. The results revealed that early ferrite-graphite decohesion and micro-cracks inside the ferrite were formed at the stress range of 280–330 MPa, where a kink occurred in the stress-strain response, suggesting the dissipation of energy in both plastic deformation and crack initiation. Some micro-cracks initiated and propagated inside the ferrite but were arrested within the ferrite zone before propagating in the pearlite. Digital Image Correlation (DIC) was used to measure local strains in the deformed micrographs obtained from the in-situ tensile test. Higher strain localization in the microstructure was measured for the areas in which the early ferrite-graphite decohesions occurred or the micro-cracks initiated. © 2017 Elsevier B.V.
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| 8. |
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| 9. |
- Sujakhu, S., et al.
(författare)
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On the fatigue damage micromechanisms in Si-solution-strengthened spheroidal graphite cast iron
- 2018
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Ingår i: Fatigue & Fracture of Engineering Materials & Structures. - : John Wiley & Sons. - 8756-758X .- 1460-2695. ; 41:3, s. 625-641
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Tidskriftsartikel (refereegranskat)abstract
- Graphite nodules in spheroidal graphite cast iron (SGI) play a vital role in fatigue crack initiation and propagation. Graphite nodules growth morphology can go through transitions to form degenerated graphite elements other than spheroidal graphite nodules in SGI microstructure. These graphite particles significantly influence damage micromechanisms in SGI and could act differently than spheroidal graphite nodules. Most of the damage mechanism studies on SGI focused on the role of spheroidal graphite nodules on the stable crack propagation region. The role of degenerated graphite elements on SGI damage mechanisms has not been frequently studied. In this work, fatigue crack initiation and propagation tests were conducted on EN-GJS-500-14 and observed under scanning electron microscope to understand the damage mechanisms for different graphite shapes. Crack initiation tests showed a dominant influence of degenerated graphite elements where early cracks initiated in the microstructure. Most of the spheroidal graphite nodules were unaffected at the early crack initiation stage, but few of them showed decohesion from the ferrite matrix and internal cracking. In the crack propagation region, graphite/ferrite matrix decohesion was the frequent damage mechanism observed with noticeable crack branching around graphite nodules and the crack passing through degenerated graphite elements. Finally, graphite nodules after decohesion acted like voids which grew and coalesced to form microcracks eventually causing rapid fracture of the remaining section.
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| 10. |
- Amiri, H, et al.
(författare)
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European Cooperative Acute Stroke Study-4: Extending the time for thrombolysis in emergency neurological deficits ECASS-4: ExTEND
- 2016
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Ingår i: International journal of stroke : official journal of the International Stroke Society. - : SAGE Publications. - 1747-4949. ; 11:2, s. 260-267
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Tidskriftsartikel (refereegranskat)abstract
- Thrombolytic therapy with recombinant tissue plasminogen activator (rt-PA) is an effective and approved therapy for acute ischemic stroke within 4.5 h of onset except for USA, Canada, Croatia, and Moldovia with a current 3 h label. We hypothesized that ischemic stroke patients selected with significant penumbral mismatch on magnetic resonance imaging (MRI) at 4.5–9 h after onset of stroke will have improved clinical outcomes when given intravenous rt-PA (alteplase) compared to placebo. Study design ECASS-4: ExTEND is an investigator driven, phase 3, randomized, multi-center, double-blind, placebo-controlled study. Ischemic stroke patients presenting within 4.5 and 9 h of stroke onset, who fulfil clinical requirements (National Institutes of Health Stroke Score (NIHSS) 4–26 and pre-stroke modified Rankin Scale (mRS) 0–1) will undergo MRI. Patients who meet imaging criteria (infarct core volume <100 ml, perfusion lesion: infarct core mismatch ratio >1.2 and perfusion lesion minimum volume of 20 ml) additionally will be randomized to either rt-PA or placebo. Study outcome The primary outcome measure will be the categorical shift in the mRS at day 90. Clinical secondary outcomes will be disability at day 90 dichotomized as favorable outcome mRS 0–1 at day 90. Tertiary endpoints include reduction in the NIHSS by 11 or more points or reaching 0–1 at day 90, reperfusion and recanalization at 24 h post stroke as well as depression, life quality, and cognitive impairment at day 90. Safety endpoints will include symptomatic intracranial hemorrhage (ICH) and death.
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