Candidate Electromagnetic Counterpart to the Binary Black Hole Merger Gravitational-Wave Event S190521g.

We report the first plausible optical electromagnetic counterpart to a (candidate) binary black hole merger. Detected by the Zwicky Transient Facility, the electromagnetic flare is consistent with expectations for a kicked binary black hole merger in the accretion disk of an active galactic nucleus [B. McKernan, K. E. S. Ford, I. Bartos et al., Astrophys. J. Lett. 884, L50 (2019)AJLEEY2041-821310.3847/2041-8213/ab4886] and is unlikely [

An image of an exoplanet separated by two diffraction beamwidths from a star.

Three exoplanets around the star HR 8799 have recently been discovered by means of differential imaging with large telescopes. Bright scattered starlight limits high-contrast imaging to large angular offsets, currently of the order of ten diffraction beamwidths, 10lambda/D, of the star (where lambda is the wavelength and D is the aperture diameter). Imaging faint planets at smaller angles calls for reducing the starlight and associated photon and speckle noise before detection, while efficiently transmitting nearby planet light. To carry out initial demonstrations of reduced-angle high-contrast coronagraphy, we installed a vortex coronagraph capable of reaching small angles behind a small, well-corrected telescope subaperture that provides low levels of scattered starlight. Here we report the detection of all three HR 8799 planets with the resultant small-aperture (1.5 m) system, for which only 2lambda/D separate the innermost planet from the star, with a final noise level within a factor of two of that given by photon statistics. Similar well-corrected small-angle coronagraphs should thus be able to detect exoplanets located even closer to their host stars with larger ground-based telescopes, and also allow a reduction in the size of potential space telescopes aimed at the imaging of very faint terrestrial planets.

In situ study of mass transfer in aqueous solutions under high pressures via Raman spectroscopy: a new method for the determination of diffusion coefficients of methane in water near hydrate formation conditions.

A new method was developed for in situ study of the diffusive transfer of methane in aqueous solution under high pressures near hydrate formation conditions within an optical capillary cell. Time-dependent Raman spectra of the solution at several different spots along the one-dimensional diffusion path were collected and thus the varying composition profile of the solution was monitored. Diffusion coefficients were estimated by the least squares method based on the variations in methane concentration data in space and time in the cell. The measured diffusion coefficients of methane in water at the liquid (L)-vapor (V) stable region and L-V metastable region are close to previously reported values determined at lower pressure and similar temperature. This in situ monitoring method was demonstrated to be suitable for the study of mass transfer in aqueous solution under high pressure and at various temperature conditions and will be applied to the study of nucleation and dissolution kinetics of methane hydrate in a hydrate-water system where the interaction of methane and water would be more complicated than that presented here for the L-V metastable condition.

Transformations in methane hydrates.

Detailed study of pure methane hydrate in a diamond cell with in situ optical, Raman, and x-ray microprobe techniques reveals two previously unknown structures, structure II and structure H, at high pressures. The structure II methane hydrate at 250 MPa has a cubic unit cell of a = 17.158(2) A and volume V = 5051.3(13) A(3); structure H at 600 MPa has a hexagonal unit cell of a = 11.980(2) A, c = 9.992(3) A, and V = 1241.9(5) A(3). The compositions of these two investigated phases are still not known. With the effects of pressure and the presence of other gases in the structure, the structure II phase is likely to dominate over the known structure I methane hydrate within deep hydrate-bearing sediments underlying continental margins.

Outsourcing inpatient i.v. compounding: expense and medication error implications.

A quasi-experiment was conducted to evaluate differences in intravenous (i.v.) drug compounding costs and frequency of medication administration errors of omission before and after outsourcing the hospital's i.v. admixture refill program to an alternate site home i.v. infusion pharmacy. As part of the outsourcing changes, the pharmacy redeployed an i.v. admixture technician to do i.v. recycling on the nursing units. The study was a single subject, pretest, posttest (within subjects) design using an observer. The independent variables were outsourcing and having an i.v. recycling technician. The dependent variables were medication errors of omission and costs directly associated with the two i.v. programs. A statistically significant reduction in the frequency of medication administration errors of omission was associated with implementation of the outsourcing program. In addition, first year expenses were reduced by an estimated $86,356.

Medication administration by non-RN personnel: a safe and cost-effective response to the RN shortage.

The results of this study strongly suggest that medication administration in the acute care community hospital setting can be safely and cost-effectively handled by non-RN personnel. In adopting such a strategy, an acute care institution can expect better utilization of existing RN resources and improved overall institutional quality, thus increasing the chances of long-term survival in the marketplace. In addition, the acute care institution can save money by avoiding unrestrained spending related to scarce RN resources (e.g., recruitment costs, agency use costs, and orientation costs due to high attrition). With society expecting more and higher quality services, hospital administrators may have an opportunity to offer the health care customer safer and less expensive medication administration services.

Chemical weathering in central iceland: an analog of pre-silurian weathering.

The rate of chemical weathering in central Iceland is two to three times more rapid in areas with plant cover than in barren areas. This relatively small difference in chemical weathering rates suggests that atmospheric CO(2), pressures no greater than five times the present value were needed to sustain present-day rates of chemical weathering before the development of higher land plants in the Silurian.