Why every observatory needs a disco ball

Commercial disco balls provide a safe, effective and instructive way of observing the Sun. We explore the optics of solar projections with disco balls, and find that while sunspot observations are challenging, the solar disk and its changes during eclipses are easy and fun to observe. We explore the disco ball's potential for observing the moon and other bright astronomical phenomena.Comment: 6 pages, 7 figures. Submitted to Physics Education. Comments welcom

The surprisingly low carbon mass in the debris disk around HD 32297

Gas has been detected in a number of debris disks. It is likely secondary, i.e. produced by colliding solids. Here, we report ALMA Band 8 observations of neutral carbon in the CO-rich debris disk around the 15--30 Myr old A-type star HD 32297. We find that C$^0$ is located in a ring at $\sim$110 au with a FWHM of $\sim$80 au, and has a mass of $(3.5\pm0.2)\times10^{-3}$ M$_\oplus$. Naively, such a surprisingly small mass can be accumulated from CO photo-dissociation in a time as short as $\sim$10$^4$ yr. We develop a simple model for gas production and destruction in this system, properly accounting for CO self-shielding and shielding by neutral carbon, and introducing a removal mechanism for carbon gas. We find that the most likely scenario to explain both C$^0$ and CO observations, is one where the carbon gas is rapidly removed on a timescale of order a thousand years and the system maintains a very high CO production rate of $\sim$15 M$_\oplus$ Myr$^{-1}$, much higher than the rate of dust grind-down. We propose a possible scenario to meet these peculiar conditions: the capture of carbon onto dust grains, followed by rapid CO re-formation and re-release. In steady state, CO would continuously be recycled, producing a CO-rich gas ring that shows no appreciable spreading over time. This picture might be extended to explain other gas-rich debris disks.Comment: accepted for publication in the Ap

Additional file 1 of Association between intravenous iron therapy and short-term mortality risk in older patients undergoing hip fracture surgery: an observational study

Additional file 1: Table S1. Causes of death among the patients who died within 30-days postoperatively. Table S2. Demographics of patients who died before hemoglobin level between day 14 to 30 was measured

Association between intravenous iron therapy and short-term mortality risk in older patients undergoing hip fracture surgery: an observational study

Abstract Background Anemia is common among ortho-geriatric hip fracture patients and is associated with prolonged recovery and increased postoperative mortality rate. Intravenous iron seems to increase hemoglobin recovery and reduce the mortality rate in patients undergoing orthopedic surgeries. This study investigated the association between short-term mortality risk and intravenous iron therapy in older patients undergoing hip fracture surgery. Methods This observational study included 210 patients undergoing hip fracture surgery from July 2018 to May 2020. These 210 patients were alive and had a hemoglobin ≤ 6.5 mmol/L on the 3rd postoperative day. In May 2019, a local intravenous iron therapy protocol was implemented and recommended intravenous iron (Monofer©) if hemoglobin on the 3rd postoperative day was ≤ 6.5 mmol/L. According to the treatment of postoperative anemia between the 1st and 3rd day post-surgery, the patients were divided into four groups: no treatment (n=52), blood transfusion (n=38), IV Monofer (n=80), and blood transfusion and IV Monofer (n=40). Primary outcome was 30-day mortality post-surgery. The secondary outcome was the impact on hemoglobin level 14–30 days postoperatively. Multivariable Cox regression was used to estimate the 30-day mortality standardized for covariates. Results Of 210 patients, 17 (8.1%) died within 30 days after surgery. There was a significantly lower mortality among the patients who received IV Monofer compared to those who received no treatment (HR 0.17, 95% CI [0.03–0.93], P = 0.041). Among the 86 patients with available hemoglobin measurements within 14 to 30 days post-surgery, there was no significant difference in hemoglobin level between the various treatment groups (mean 6.6 mmol/L, P = 0.1165). Conclusion IV Monofer on the 3rd postoperative day in older hip fracture patients seemed to reduce 30-day mortality compared with no treatment. No significant differences in hemoglobin levels between 14 and 30 days post-surgery across treatment groups were found, although this was assessed in a subset of patients with available hemoglobin levels warranting further study

Association between intravenous iron therapy and short-term mortality risk in older patients undergoing hip fracture surgery: an observational study

Abstract Background Anemia is common among ortho-geriatric hip fracture patients and is associated with prolonged recovery and increased postoperative mortality rate. Intravenous iron seems to increase hemoglobin recovery and reduce the mortality rate in patients undergoing orthopedic surgeries. This study investigated the association between short-term mortality risk and intravenous iron therapy in older patients undergoing hip fracture surgery. Methods This observational study included 210 patients undergoing hip fracture surgery from July 2018 to May 2020. These 210 patients were alive and had a hemoglobin ≤ 6.5 mmol/L on the 3rd postoperative day. In May 2019, a local intravenous iron therapy protocol was implemented and recommended intravenous iron (Monofer©) if hemoglobin on the 3rd postoperative day was ≤ 6.5 mmol/L. According to the treatment of postoperative anemia between the 1st and 3rd day post-surgery, the patients were divided into four groups: no treatment (n=52), blood transfusion (n=38), IV Monofer (n=80), and blood transfusion and IV Monofer (n=40). Primary outcome was 30-day mortality post-surgery. The secondary outcome was the impact on hemoglobin level 14–30 days postoperatively. Multivariable Cox regression was used to estimate the 30-day mortality standardized for covariates. Results Of 210 patients, 17 (8.1%) died within 30 days after surgery. There was a significantly lower mortality among the patients who received IV Monofer compared to those who received no treatment (HR 0.17, 95% CI [0.03–0.93], P = 0.041). Among the 86 patients with available hemoglobin measurements within 14 to 30 days post-surgery, there was no significant difference in hemoglobin level between the various treatment groups (mean 6.6 mmol/L, P = 0.1165). Conclusion IV Monofer on the 3rd postoperative day in older hip fracture patients seemed to reduce 30-day mortality compared with no treatment. No significant differences in hemoglobin levels between 14 and 30 days post-surgery across treatment groups were found, although this was assessed in a subset of patients with available hemoglobin levels warranting further study