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The Easton metamorphic suite of the Northwest Cascades thrust system is an exhumed Jurassic-Cretaceous subduction complex that can be used to test models for subduction zone deformation. Regional blueschist and greenschist within the Easton were accreted in a thermally evolving subduction zone between 150 – 136 Ma. Two units of the Easton metamorphic suite, the Darrington phyllite and the Shuksan greenschist, were originally interpreted as a coherent unit that subducted together in a zone of distributed deformation. The phyllite and greenschist are exposed in a gently SE plunging, steeply inclined, NE vergent, regional synclinorium in the Finney Creek area. New field mapping, microstructural analysis, and thermometry suggest the Darrington phyllite includes a new unit, the Silver phyllite. The Darrington phyllite contains two foliations with the dominant S2 foliation defined by aligned Gr + Ms. The Silver phyllite also preserves two foliations with S1 defined by aligned Ep + Gr in Ab porphyroclasts and relict Ms in fold hinges. The S1 foliation is variably overprinted by the dominant S2 axial planar cleavage of aligned Ms + Chl (148 –140 Ma) that intensifies with proximity to the greenschist contact. In contrast, the Shuksan greenschist dominantly preserves an S1 foliation (~140 Ma) of aligned Ep + Act/Gln + Ms + Chl that is variably overprinted by a weak S2 (140 – 136 Ma) that is axial planar to tight folds in the greenschist and the regional synclinorium. The contact between Silver phyllite and Shuksan greenschist is marked by a Ms + Chl + Ab mylonite that is parallel to the S2 fabric in both units. Raman spectroscopy of carbonaceous material (RSCM) suggests the three units have different thermal histories. Graphite in the Darrington phyllite S2 foliation yields temperatures of 374 – 400 C. The Silver phyllite S1 assemblage records RSCM temperatures of 430 – 450 C while previous Chl ­– Ms thermometry from S2 yielded 310 – 340 C. In contrast, the Shuksan greenschist S1 formed at peak metamorphic conditions of ~360 C. The deformation and thermal history combined with existing Ar/Ar ages suggest that cooling of the Silver phyllite from S1 to S2 was synchronous with prograde metamorphism and formation of S1 in the greenschist during underplating, and that these unit were subducted as discrete tectonic slices rather than as a coherent unit. 

Numerical models of subduction initiation and observations of exhumed subduction complexes indicate that the early stages of subduction are characterized by rapid cooling followed by a prolonged steady thermal state that can last tens of millions of years. Several mechanisms are proposed to drive cooling in subduction zones and include thermal relaxation, exhumation, and underplating, but determining the relative contribution of each mechanism in the history of an exhumed subduction complex can be difficult. The Easton metamorphic suite in the Northwest Cascades of Washington is a Jurassic-Cretaceous subduction complex that records the subduction and accretion of distinct units within a thermally maturing nascent subduction zone. The region preserves an inverted metamorphic sequence with metamorphic temperatures and ages that decrease structurally downward from an early accreted metamorphic sole to younger regionally extensive blueschist facies units. In the metamorphic sole Grt±Cpx amphibolite was metamorphosed at 750-800 C at 1.0 GPa prior to 167 Ma. The amphibolite is underlain by a high temperature Grt-Ab-Gln blueschist that was metamorphosed at ~530 C and 1.0 GPa at 165 Ma. The contact between the units is gradational and the general lack of deformation suggests initial cooling to lower temperatures may have been caused by cooling of the overall subduction zone. Retrograde Lws-Ep-Gln-Ms assemblages suggest that cooling of both the amphibolite and high-grade blueschist units to below 400-500 C was caused by exhumation to 0.7 GPa by 157 Ma. In the regionally extensive blueschist units, Ep-Ab-Chl-Ms±Grt±Lws phyllite was metamorphosed at 430-450 C and 0.7 GPa by 149 Ma. Retrograde fabrics in the phyllite record similar temperatures to peak metamorphic conditions in an underlying Ep-Ab-Gln/Act greenschist/blueschist unit that was accreted and metamorphosed at ≤350 C by ≤140 Ma. The contact between the phyllite and greenschist is marked by a high strain mylonite zone and the combined observations suggest that cooling of the phyllite was driven by underplating of the younger greenschist unit. The observed assemblages and fabrics within the Easton metamorphic suite record cooling as the result of thermal relaxation, underplating, and exhumation at distinctly different times in the subduction history. 

Medical imaging deep learning models are often large and complex, requiring specialized hardware to train and evaluate these models. To address such issues, we propose the PocketNet paradigm to reduce the size of deep learning models by throttling the growth of the number of channels in convolutional neural networks. We demonstrate that, for a range of segmentation and classification tasks, PocketNet architectures produce results comparable to that of conventional neural networks while reducing the number of parameters by multiple orders of magnitude, using up to 90% less GPU memory, and speeding up training times by up to 40%, thereby allowing such models to be trained and deployed in resource-constrained settings. 

Abstract We present a highly complete sample of broad-line (Type 1) QSOs out to z ∼ 3 selected by their mid-infrared colors, a method that is minimally affected by dust reddening. We remove host-galaxy emission from the spectra and fit for excess reddening in the residual QSOs, resulting in a Gaussian distribution of colors for unreddened (blue) QSOs, with a tail extending toward heavily reddened (red) QSOs, defined as having E ( B − V ) > 0.25. This radio-independent selection method enables us to compare red and blue QSO radio properties in both the FIRST (1.4 GHz) and VLASS (2–4 GHz) surveys. Consistent with recent results from optically selected QSOs from SDSS, we find that red QSOs have a significantly higher detection fraction and a higher fraction of compact radio morphologies at both frequencies. We employ radio stacking to investigate the median radio properties of the QSOs including those that are undetected in FIRST and VLASS, finding that red QSOs have significantly brighter radio emission and steeper radio spectral slopes compared with blue QSOs. Finally, we find that the incidence of red QSOs is strongly luminosity dependent, where red QSOs make up >40% of all QSOs at the highest luminosities. Overall, red QSOs comprise ∼40% of higher luminosity QSOs, dropping to only a few percent at lower luminosities. Furthermore, red QSOs make up a larger percentage of the radio-detected QSO population. We argue that dusty AGN-driven winds are responsible for both the obscuration as well as excess radio emission seen in red QSOs. 

Abstract We present UV and/or optical observations and models of SN 2023ixf, a type II supernova (SN) located in Messier 101 at 6.9 Mpc. Early time (flash) spectroscopy of SN 2023ixf, obtained primarily at Lick Observatory, reveals emission lines of Hi, Hei/ii, Civ, and Niii/iv/vwith a narrow core and broad, symmetric wings arising from the photoionization of dense, close-in circumstellar material (CSM) located around the progenitor star prior to shock breakout. These electron-scattering broadened line profiles persist for ∼8 days with respect to first light, at which time Doppler broadened the features from the fastest SN ejecta form, suggesting a reduction in CSM density atr≳ 10¹⁵cm. The early time light curve of SN 2023ixf shows peak absolute magnitudes (e.g.,M_u= −18.6 mag,M_g= −18.4 mag) that are ≳2 mag brighter than typical type II SNe, this photometric boost also being consistent with the shock power supplied from CSM interaction. Comparison of SN 2023ixf to a grid of light-curve and multiepoch spectral models from the non-LTE radiative transfer codeCMFGENand the radiation-hydrodynamics codeHERACLESsuggests dense, solar-metallicity CSM confined tor= (0.5–1) × 10¹⁵cm, and a progenitor mass-loss rate of $\dot{M}={10}^{-2}{M}_{\odot }$yr⁻¹. For the assumed progenitor wind velocity ofv_w= 50 km s⁻¹, this corresponds to enhanced mass loss (i.e.,superwindphase) during the last ∼3–6 yr before explosion.