ALMA High-frequency Long Baseline Campaign in 2017:Band-to-band Phase Referencing in Submillimeter Waves

In 2017, an Atacama Large Millimeter/submillimeter Array (ALMA) high-frequency long baseline campaign was organized to test image capabilities with baselines up to 16 km at submillimeter (submm) wavelengths. We investigated image qualities using ALMA receiver Bands 7, 8, 9, and 10 (285-875 GHz) by adopting band-to-band (B2B) phase referencing in which a phase calibrator is tracked at a lower frequency. For B2B phase referencing, it is expected that a closer phase calibrator to a target can be used, comparing to standard in-band phase referencing. In the first step, it is ensured that an instrumental phase offset difference between low- and high-frequency Bands can be removed using a differential gain calibration in which a phase calibrator is certainly detected while frequency switching. In the next step, comparative experiments are arranged to investigate the image quality between B2B and in-band phase referencing with phase calibrators at various separation angles. In the final step, we conducted long baseline imaging tests for a quasar at 289 GHz in Band 7 and 405 GHz in Band 8 and complex structure sources of HL Tau and VY CMa at ~670 GHz in Band 9. The B2B phase referencing was successfully applied, allowing us to achieve an angular resolution of 14x11 and 10x8 mas for HL Tau and VY CMa, respectively. There is a high probability of finding a low-frequency calibrator within 5.4 deg in B2B phase referencing, bright enough to use an 8 s scan length combined with a 7.5 GHz bandwidth.Comment: 61 pages, 17 figures, 8 table

ALMA high-frequency long-baseline campaign in 2017: an investigation of phase-referencing cycle times and effective baseline lengths using band-to-band and in-band phase calibration techniques

Interstellar matter and star formatio

ALMA high-frequency long baseline campaign in 2017: Band-to-band phase referencing in submillimeter waves

Instrumentatio

Hematopoietic stem cell transplantation for DLBCL: a report from the European Society for Blood and Marrow Transplantation on more than 40,000 patients over 32 years

Autologous(auto-) and allogeneic(allo-) hematopoietic stem cell transplantation (HSCT) are key treatments for relapsed/refractory diffuse large B-cell lymphoma (DLBCL), although their roles are challenged by CAR-T-cells and other immunotherapies. We examined the transplantation trends and outcomes for DLBCL patients undergoing auto-/allo-HSCT between 1990 and 2021 reported to EBMT. Over this period, 41,148 patients underwent auto-HSCT, peaking at 1911 cases in 2016, while allo-HSCT saw a maximum of 294 cases in 2018. The recent decline in transplants corresponds to increased CAR-T treatments (1117 cases in 2021). Median age for auto-HSCT rose from 42 (1990-1994) to 58 years (2015-2021), with peripheral blood becoming the primary stem cell source post-1994. Allo-HSCT median age increased from 36 (1990-1994) to 54 (2015-2021) years, with mobilized blood as the primary source post-1998 and reduced intensity conditioning post-2000. Unrelated and mismatched allo-HSCT accounted for 50% and 19% of allo-HSCT in 2015-2021. Three-year overall survival (OS) after auto-HSCT improved from 56% (1990-1994) to 70% (2015-2021), p 40,000 transplants, providing insights for evaluating emerging DLBCL therapies

ALMA high-frequency long-baseline campaign in 2017: an investigation of phase-referencing cycle times and effective baseline lengths using band-to-band and in-band phase calibration techniques

Interstellar matter and star formatio

ALMA Band-to-band phase referencing: Imaging capabilities on long baselines and high frequencies

Instrumentatio

ALMA high-frequency long-baseline campaign in 2017: a comparison of the band-to-band and in-band phase calibration techniques and phase-calibrator separation angles

Instrumentatio

ALMA High-frequency Long-baseline Campaign in 2017: An Investigation of Phase-referencing Cycle Times and Effective Baseline Lengths Using Band-to-band and In-band Phase Calibration Techniques

Abstract The Atacama Large Millimeter/submillimeter Array can achieve unprecedented spatial resolutions of 15 to 5 mas with the longest baselines of 16 km and observing at the highest frequencies of 275–950 GHz (1.09–0.30 mm). Two conditions are paramount for successful observations at these frequencies: a phase calibrator in close proximity to the science target and a stable-enough atmosphere to provide a low residual phase rms post-phase-referencing. We investigate the effect of phase-referencing cycle times, for in-band and band-to-band (B2B) observing techniques, using close and distant phase calibrators, at bands 7, 8, and 9 for baselines &gt;2000 m. We find that (1) the phase rms estimated from baselines longer than the effective baseline increases as a function of time . (2) The expected coherence estimated using the expected phase rms corresponds well to the achieved image coherence. (3) Faster phase-referencing cycle times (&lt;1 minute) improve phase calibration accuracy and image coherence when close phase calibrators (&lt;2°) are used. (4) For cycle times &lt;2 minutes the negative impact of distant phase calibrators dominates the phase error budget. We also explore whether a theoretical parameterization of the effective baseline used to estimate the phase rms and a phase stability measurement, combined with an empirical parameterization of coherence degradation as a function of calibrator separation, is suitable in estimating the expected coherence of target images. The latter proves to be more accurate. Finally, we illustrate a pragmatic approach in establishing an optimal observing strategy via dynamic cycle times and on-calibrator scan lengths.</jats:p