Precise Measurements of Self-absorbed Rising Reverse Shock Emission from Gamma-ray Burst 221009A

The deaths of massive stars are sometimes accompanied by the launch of highly relativistic and collimated jets. If the jet is pointed towards Earth, we observe a "prompt" gamma-ray burst due to internal shocks or magnetic reconnection events within the jet, followed by a long-lived broadband synchrotron afterglow as the jet interacts with the circum-burst material. While there is solid observational evidence that emission from multiple shocks contributes to the afterglow signature, detailed studies of the reverse shock, which travels back into the explosion ejecta, are hampered by a lack of early-time observations, particularly in the radio band. We present rapid follow-up radio observations of the exceptionally bright gamma-ray burst GRB 221009A which reveal an optically thick rising component from the reverse shock in unprecedented detail both temporally and in frequency space. From this, we are able to constrain the size, Lorentz factor, and internal energy of the outflow while providing accurate predictions for the location of the peak frequency of the reverse shock in the first few hours after the burst.Comment: 11 figures, 4 table

Lessons to be learned in adoption of autonomous equipment for field crops

Autonomous equipment for crop production is on the verge of technical and economic feasibility, but government regulation may slow its adoption. Key regulatory issues include requirements for on-site human supervision, liability for autonomous machine error, and intellectual property in robotic learning. As an example of the impact of regulation on the economic benefits of autonomous crop equipment, analysis from the United Kingdom suggests that requiring 100% on-site human supervision almost wipes out the economic benefits of autonomous crop equipment for small and medium farms and increases the economies-of-scale advantage of larger farms

Improved 21 cm Epoch of Reionization Power Spectrum Measurements with a Hybrid Foreground Subtraction and Avoidance Technique

Observations of the 21 cm Epoch of Reionization signal are dominated by Galactic and extragalactic foregrounds. The need for foreground removal has led to the development of two main techniques, often referred to as “foreground avoidance” and “foreground subtraction.” Avoidance is associated with filtering foregrounds in Fourier space, while subtraction uses an explicit foreground model that is removed. Using 1088 hr of data from the 64-element PAPER array, we demonstrate that subtraction of a foreground model prior to delay-space foreground filtering results in a modest but measurable improvement of the performance of the filter. This proof-of-concept result shows that improvement stems from the reduced dynamic range requirements needed for the foreground filter: subtraction of a foreground model reduces the total foreground power, so for a fixed dynamic range, the filter can push toward fainter limits. We also find that the choice of window function used in the foreground filter can have an appreciable affect on the performance near the edges of the observing band. We demonstrate these effects using a smaller 3 hr sampling of data from the MWA, and find that the hybrid filtering and subtraction removal approach provides similar improvements across the band as seen in the case with PAPER-64

Transformation of CMML to AML presenting with acute kidney injury.

Characterized by bone marrow dysplasia and peripheral blood monocytosis, chronic myelomonocytic leukemia (CMML) is one of the most aggressive chronic leukemias and has a propensity for progression to acute myeloid leukemia (AML). Patients with newly diagnosed AML generally present with symptoms related to complications of pancytopenia but can also present with renal insufficiency. We present a 79-year-old male with a past medical history of CMML and chronic kidney disease stage 3 (baseline creatinine 1.8 mg/dL) who presented with one day of inability to urinate and 20-lb unintentional weight loss, fatigue, and bone pain over 3 months. Laboratory evaluation revealed leukocytosis of 88.5 x 1

Transformation of CMML to AML presenting with acute kidney injury.

Characterized by bone marrow dysplasia and peripheral blood monocytosis, chronic myelomonocytic leukemia (CMML) is one of the most aggressive chronic leukemias and has a propensity for progression to acute myeloid leukemia (AML). Patients with newly diagnosed AML generally present with symptoms related to complications of pancytopenia but can also present with renal insufficiency. We present a 79-year-old male with a past medical history of CMML and chronic kidney disease stage 3 (baseline creatinine 1.8 mg/dL) who presented with one day of inability to urinate and 20-lb unintentional weight loss, fatigue, and bone pain over 3 months. Laboratory evaluation revealed leukocytosis of 88.5 x 1

Verification of R-matrix calculations for charged-particle reactions in the resolved resonance region for the 7^{7}Be system

International audienceR-matrix theory is used to describe nuclear reactions in the resolved resonance region. It uses information on bound states and low energy resonances to accurately parametrize cross sections on the resonances as well as the non-resonant background. Since the seminal work of Lane and Thomas (1958), the approach has been widely used to analyze experimental cross-section data in a broad range of fields spanning nuclear reaction dynamics, nuclear astrophysics, ion beam analysis and their applications. Different R-matrix codes have been developed and used in these different applications with very little communication among the developers or practitioners on the capabilities, achievements or limitations of the codes. A limited comparison among three R-matrix codes on neutron-induced reactions was performed by the International Atomic Energy Agency (IAEA) International Evaluation of Neutron Cross Section Standards project (2007). Since then, significant progress has been made in their implementation of the R-matrix algorithms, and R-matrix codes have enhanced capabilities. In this paper we present, for the first time, the results of a comprehensive effort to verify the most widely used R-matrix codes in the various fields of nuclear science and applications: AMUR, AZURE2, CONRAD, EDA, FRESCO, GECCCOS, and SAMMY. In addition to the description of the capabilities of the codes and their specifications, we discuss the results of a joint exercise which was coordinated by the International Atomic Energy Agency. The aim of the exercise was to compare calculations of charged-particle reaction cross sections for the light composite system$^{7}$Be. The calculations were performed by the codes using identical input R-matrix parameters and other specifications and were limited to charged-particle channels

Evaluation of light-element reactions in the resolved resonance region

Light-element reactions at low energies in the resolved resonance region are important for a range of applications in basic and applied sciences including nuclear reactors, nonproliferation, cultural heritage, forensics and environmental control, rare event investigations and nuclear astrophysics. In this paper, we report on an effort to evaluate charged-particle cross sections in the resolved resonance region and produce evaluated nuclear data files for further processing and inclusion in evaluated data libraries. We discuss the open issues in R-matrix calculations as we extend to higher energies, such as dealing with the rapidly growing number of open channels and merging with the regime of smooth cross sections described by the statistical model, and present attempts to address these issues in neutron-induced reactions relevant to nuclear reactor applications

Racial and Ethnic Differences in Kidney Function Decline among Persons without Chronic Kidney Disease

Whether the rate of kidney function decline before the onset of CKD differs among racial and ethnic groups remains unclear. Here, we evaluated kidney function decline and incident CKD among white, black, Hispanic, and Chinese participants in the Multi-Ethnic Study of Atherosclerosis (MESA) during 5 years of follow-up. We estimated GFR using both cystatin C (eGFRcys) and creatinine (eGFRcreat). The definition of incident CKD required eGFRcys <60 ml/min per 1.73 m2 and a decline in eGFRcys ≥1 ml/min per year. Among participants with eGFRcreat >60 ml/min per 1.73 m2 at baseline, blacks had a significantly higher rate of kidney function decline than whites (0.31 ml/min per 1.73 m2/yr faster on average, P = 0.001), even after adjusting for multiple potential confounders. Among Hispanics, Dominicans and Puerto Ricans had faster rates of decline than whites (0.55 and 0.47 ml/min per 1.73 m2/yr faster, respectively). Mexicans, South Americans, or other Hispanics had similar rates of decline compared to whites. We did not detect significant differences in the rates of kidney function decline among Chinese and white participants. Among those with normal or near-normal kidney function at baseline, blacks and Hispanics had the highest rates of incident CKD during follow-up. Adjustment for comorbidities attenuated some of these differences. In conclusion, the average rate of kidney function decline before the onset of CKD differs among racial and ethnic groups. Traditional risk factors do not explain these differences fully, highlighting the need to explore these disparities

Circulating vitamin D metabolites and kidney disease in type 1 diabetes

CONTEXT: Impaired vitamin D metabolism may contribute to the development and progression of diabetic kidney disease. OBJECTIVE: The aim of the study was to test associations of circulating vitamin D metabolites with risks of incident microalbuminuria, impaired glomerular filtration rate (GFR), and hypertension in type 1 diabetes. DESIGN: We performed a cohort study of 1193 participants in the Diabetes Control and Complications Trial (DCCT), a randomized clinical trial of intensive diabetes therapy, and its observational follow-up, the Epidemiology of Diabetes Interventions and Complications (EDIC) Study. We measured plasma concentrations of 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D, and 24,25-dihydroxyvitamin D by mass spectrometry at the end of the DCCT and tested associations with incident microalbuminuria, impaired GFR, and hypertension over up to 16 yr of EDIC follow-up. RESULTS: At the time metabolites were measured, mean age was 32.4 yr; mean duration of diabetes, 7.5 yr; mean iothalamate GFR, 132.9 ml/min/1.73 m(2); and geometric mean albumin excretion rate, 11.8 mg/24 h. Over follow-up, 166 cases of microalbuminuria, 54 cases of impaired GFR, and 541 cases of hypertension were observed. Compared with 25(OH)D of at least 30 ng/ml, 25(OH)D below 20 ng/ml was associated with a 65% higher risk of microalbuminuria (95% confidence interval, 7 to 154%) in adjusted analyses. Low concentrations of 24,25-dihydroxyvitamin D, but not 1,25-dihydroxyvitamin D, were also associated with increased risk of microalbuminuria. No circulating vitamin D metabolite was associated with risk of impaired GFR or hypertension. CONCLUSIONS: Low plasma concentrations of 25(OH)D and 24,25-dihydroxyvitamin D are associated with increased risk of microalbuminuria in type 1 diabetes. In contrast, we did not find evidence linking impaired vitamin D metabolism to early GFR loss or the development of hypertension