GrailQuest: hunting for atoms of space and time hidden in the wrinkle of Space-Time

GrailQuest (Gamma Ray Astronomy International Laboratory for QUantum Exploration of Space-Time) is a mission concept based on a constellation (hundreds/thousands) of nano/micro/small-satellites in low (or near) Earth orbits. Each satellite hosts a non-collimated array of scintillator crystals coupled with Silicon Drift Detectors with broad energy band coverage (keV-MeV range) and excellent temporal resolution (≤ 100 nanoseconds) each with effective area ∼100cm2. This simple and robust design allows for mass-production of the satellites of the fleet. This revolutionary approach implies a huge reduction of costs, flexibility in the segmented launching strategy, and an incremental long-term plan to increase the number of detectors and their performance; this will result in a living observatory for next-generation, space-based astronomical facilities. GrailQuest is conceived as an all-sky monitor for fast localisation of high signal-to-noise ratio transients in the X-/gamma-ray band, e.g. the elusive electromagnetic counterparts of gravitational wave events. Robust temporal triangulation techniques will allow unprecedented localisation capabilities, in the keV-MeV band, of a few arcseconds or below, depending on the temporal structure of the transient event. The ambitious ultimate goal of this mission is to perform the first experiment, in quantum gravity, to directly probe space-time structure down to the minuscule Planck scale, by constraining or measuring a first-order dispersion relation for light in vacuo. This is obtained by detecting delays between photons of different energies in the prompt emission of Gamma-Ray Bursts

Modeling of Tooling-Workpiece Interactions on Random Surfaces

Abrasive processes, commonly employed in manufacturing, are difficult to model because they rely on brittle particles with unknown geometry and multiple points of contact. Newly developed microreplicated abrasives allow for control of abrasive grit properties such as size, shape, and distribution. This paper proposes and validates a parametric model of abrasive machining that allows for studying the interaction of this particular tooling with randomly generated surfaces. In this work, the parameters of a probability distribution function that represents the workpiece surface are approximated by profilometry data. Monte Carlo simulation is used to account for inter- and intraspecimen variability. A geometric representation is used to mathematically represent the interaction between workpiece and tool. The results show good correlation between theoretical and actual values. This approach could be used to aid in tool geometry design as well as in process parameter optimization

Sodium-Glucose Cotransporter-2 Inhibitor Use is Associated with a Reduced Risk of Heart Failure Hospitalization in Patients with Heart Failure with Preserved Ejection Fraction and Type 2 Diabetes Mellitus: A Real-World Study on a Diverse Urban Population

Background: Limited evidence-based therapies exist for the management of heart failure with preserved ejection fraction (HFpEF). Sodium-glucose cotransporter-2 inhibitor (SGLT2i) use in patients with systolic heart failure (HFrEF) and type-2-diabetes mellitus (T2DM) is associated with improved cardiovascular (CV) and renal outcomes. Objective: We sought to examine whether there is an association of SGLT2i use with improved CV outcomes in patients with HFpEF. Patients and methods: We conducted a single-center, retrospective review of patients with HFpEF and T2DM. The cohort was divided into two groups based on prescription of a SGLT2i or sitagliptin. The primary outcome was heart failure hospitalization (HFH); secondary outcomes were all-cause hospitalization and acute kidney injury (AKI). Results: After propensity score matching, there were 250 patients (89 in the SGLT2i group, 161 in the sitagliptin group), with a mean follow-up of 295 days. Univariate Cox regression analysis showed that the SGLT2i group had a reduced risk of HFH versus the sitagliptin group (hazard ratio (HR) 0.13; 95% confidence interval (CI) (0.05–0.36); p \u3c 0.001). The SGLT2i group had a decreased risk of all-cause hospitalization (HR 0.48; 95% CI (0.33–0.70); p \u3c 0.001) and SGLT2i had a lower risk of AKI (HR 0.39; 95% CI (0.20–0.74); p = 0.004). Conclusions: The use of SGLT2is is associated with a reduced incidence of HFH and AKI in patients with HFpEF and T2DM

Performance and simulated moment uncertainties of an ion spectrometer with asymmetric 2π field of view for ion measurements in space

Space plasma instruments provide 3D particle velocity distribution functions. Because of telemetry limitations, these cannot be transmitted in high time resolution and the plasma needs to be characterized by moments of the velocity distribution function. These moment uncertainties have vital effects on the reliability and accuracy of onboard plasma moments. We assess the measurement accuracy for magnetosheath and solar wind ions using an ion spectrometer with an asymmetric field of view designed for the all-sky measurement of low-energy ions in the magnetosheath and solar wind. We focus on moment uncertainties for the ideal spectrometer, not considering the background counts, which may have considerable effects on the uncertainties in real life. To obtain number density, bulk velocity, and temperature, different orders of moments are integrated assuming a Maxwellian velocity distribution. Based on the design specifications, we use simulations to estimate systematic and random errors for typical plasma conditions. We find that the spectrometer resolution is adequate for determining the density of solar wind (∼7% error) and magnetosheath ions (∼4% error). The resolution is also adequate for determining the temperature of solar wind (∼10% error) and magnetosheath ions (∼2% error). For high speed flows with a bulk velocity of 750 km/s and a temperature of 20 eV, the maximum density and temperature errors become 9% and 7%, respectively. The bulk velocity errors are less than 2% for all cases. The contributions of heavy ions to the systematic errors are less than 5% for magnetosheath ions and less than 8% for solar wind ions

Strong Near-infrared Spectral Variability of the Young Cloudy L Dwarf Companion VHS J1256–1257 b

Rotationally modulated variability of brown dwarfs and giant planets provides unique information about their surface brightness inhomogeneities, atmospheric circulation, cloud evolution, vertical atmospheric structure, and rotational angular momentum. We report results from Hubble Space Telescope/Wide Field Camera 3 near-infrared time-series spectroscopic observations of three companions with masses in or near the planetary regime: VHS J125601.92–125723.9 b, GSC 6214–210 B, and ROXs 42 B b. VHS J1256–1257 b exhibits strong total intensity and spectral variability with a brightness difference of 19.3% between 1.1 and 1.7 μm over 8.5 hr and even higher variability at the 24.7% level at 1.27 μm. The light curve of VHS J1256–1257 b continues to rise at the end of the observing sequence so these values represent lower limits on the full variability amplitude at this epoch. This observed variability rivals (and may surpass) the most variable brown dwarf currently known, 2MASS J21392676+0220226. The implied rotation period of VHS J1256–1257 b is ≈21–24 hr assuming sinusoidal modulations, which is unusually long for substellar objects. No significant variability is evident in the light curves of GSC 6214–210 B (<1.2%) and ROXs 42 B b (<15.6%). With a spectral type of L7, an especially red spectrum, and a young age, VHS J1256–1257 b reinforces emerging patterns between high variability amplitude, low surface gravity, and evolutionary phase near the L/T transition