PRESSURE-TEMPERATURE EVOLUTION OF METAPELITES WITHIN THE ANACONDA METAMORPHIC CORE COMPLEX, SOUTHWESTERN MONTANA

This study shows the complete metamorphic evolution of metapelitic footwall rocks in the Anaconda metamorphic core complex, located in southwestern Montana. Pseudosections were constructed using the computer program THERMOCALC (v. 3.26) in conjunction with the internally consistent dataset of Holland and Powell (1998, version 5.5, updated Nov. 2003) in the model system NCKFMASH (Na2O-CaO-K2O-FeO-MgO-Al2O3- SiO2-H2O). Microprobe data reveals that garnet is very almandine rich and contains very little manganese, thus not requiring MnO as a component in the model system. X-ray mapping of garnet within metapelites indicate only one growth phase. Petrographic analysis in conjunction with pseudosections reveal peak metamorphism occurred at 3.3-5.3 kbars and 590-665°C with an assemblage of biotite + garnet + sillimanite + quartz + plagioclase + muscovite. Chemical composition of garnet, biotite, and plagioclase all verify peak metamorphic conditions on contoured pseudosections. Evolution of footwall rocks occurred along a prograde, clockwise path that was largely stable within sillimanite stability as evidenced by its abundance. These amphibolite facies metapelites equilibrated at or near the solidus

Cryogenic Optical Position Encoders for Mechanisms in the JWST Optical Telescope Element Simulator (OSIM)

The JWST Optical Telescope Element Simulator (OSIM) is a configurable, cryogenic, optical stimulus for high fidelity ground characterization and calibration of JWST's flight instruments. OSIM and its associated Beam Image Analyzer (BIA) contain several ultra-precise, cryogenic mechanisms that enable OSIM to project point sources into the instruments according to the same optical prescription as the flight telescope images stars - correct in focal surface position and chief ray angle. OSIM's and BIA's fifteen axes of mechanisms navigate according to redundant, cryogenic, absolute, optical encoders - 32 in all operating at or below 100 K. OSIM's encoder subsystem, the engineering challenges met in its development, and the encoders' sub-micron and sub-arcsecond performance are discussed

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

If these walls could talk! : photographs, photographers and their patrons in Accra and Cape Coast, Ghana 1840-1940

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