X-ray line polarization spectroscopy of Li-like satellite line spectra

We apply the magnetic-sublevel atomic kinetics model POLAR to the calculation of polarization properties of satellite lines in Li-like Si driven by subpicosecond-duration laser pulses. We identify spectral lines whose polarization can serve as a marker of plasma anisotropy due to anisotropy in the electron distribution function. We also discuss the utility and limitations of ur current theoretical approach and point out possible future improvements and directions

Transcutaneous auricular vagus nerve stimulation influences gastric motility: A randomized, double-blind trial in healthy individuals

Background: Transcutaneous auricular vagus nerve stimulation (taVNS) has been investigated regarding its therapeutic properties in several several conditions such as epilepsy, migraine and major depressive disorder and was shown to access similar neural pathways as invasive vagus nerve stimulation. While the vagus nerve's role in gut motility is physiologically established, the effect of taVNS has scarcely been investigated in humans and yielded conflicting results. Real-time gastric magnetic resonance imaging (rtMRI) is an established reproducible method to investigate gastric motility non-invasively. Objective: To investigate the influence of taVNS on gastric motility of healthy participants using rtMRI. Methods: We conducted a randomized, double-blind study using high-frequency (HF) stimulation at 25Hz or low-frequency (LF) taVNS at 1Hz after ingestions of a standardized meal in 57 healthy participants. The gastric motility index (GMI) was determined by measuring the amplitude and velocity of the peristaltic waves using rtMRI. Results: After HF taVNS, GMI was significantly higher than after LF stimulation (p = 0.005), which was mainly attributable to a higher amplitude of the peristaltic waves (p = 0.003). Conclusion: We provide evidence that 4-h of taVNS influences gastric motility in healthy human participants for the first time using rtMRI. HF stimulation is associated with higher amplitudes of peristaltic waves in the gastric antrum compared to LF stimulation. Further studies are needed to investigate the effect of different frequencies of taVNS and its therapeutic properties in conditions with impaired gastric motility

An Expanded Set of Los Alamos OPLIB Tables in MESA: Type-1 Rosseland-mean Opacities and Solar Models

We present a set of 1194 Type-1 Rosseland-mean opacity tables for four different metallicity mixtures. These new Los Alamos OPLIB atomic radiative opacity tables are an order of magnitude larger in number than any previous opacity table release, and span regimes where previous opacity tables have not existed. For example, the new set of opacity tables expands the metallicity range to Z = 10 ^−6 to Z = 0.2, which allows improved accuracy of opacities at low and high metallicity, increases the table density in the metallicity range Z = 10 ^−4 to Z = 0.1 to enhance the accuracy of opacities drawn from interpolations across neighboring metallicities, and adds entries for hydrogen mass fractions between X = 0 and X = 0.1 including X = 10 ^−2 , 10 ^−3 , 10 ^−4 , 10 ^−5 , 10 ^−6 that can improve stellar models of hydrogen deficient stars. We implement these new OPLIB radiative opacity tables in MESA and find that calibrated solar models agree broadly with previously published helioseismic and solar neutrino results. We find differences between using the new 1194 OPLIB opacity tables and the 126 OPAL opacity tables range from ≈20% to 80% across individual chemical mixtures, up to ≈8% and ≈15% at the bottom and top of the solar convection zone respectively, and ≈7% in the solar core. We also find differences between standard solar models using different opacity table sources that are on par with altering the initial abundance mixture. We conclude that this new, open-access set of OPLIB opacity tables does not solve the solar modeling problem, and suggest the investigation of physical mechanisms other than the atomic radiative opacity

State-resolved Photodissociation and Radiative Association Data for the Molecular Hydrogen Ion

We present state-resolved (electronic, vibrational, and rotational) cross sections and rate coefficients for the photodissociation (PD) of H 2 + and radiative association (RA) of H-H + . We developed a fully quantum mechanical approach within the nonrelativistic Born-Oppenheimer approximation to describe H 2 + and calculate the data for transitions between the ground electronic state 1ss g and the 2ps u , 2pp u , 3ps u , 3pp u , 4ps u , 4fs u , 4fp u , and 4pp u electronic states (i.e., up to H 2 + n = 4). Tables of the dipole-matrix elements and energies needed to calculate stateresolved cross sections and rate coefficients will be made publicly available. These data could be important in astrophysical models when dealing with photon wavelengths (or radiation temperature distributions that are weighted toward such wavelengths) around 100 nm. For example, at these wavelengths and a material temperature of 8400 K, the LTE-averaged PD cross section via the (second electronically excited) 2pp u state is over three times larger than the PD cross section via the (first electronically excited) 2ps u state