The report of a detection of an absorption profile centred at 78 MHz in the continuum radio background spectrum by the EDGES experiment and its interpretation as the redshifted 21 cm signal of cosmological origin has become one of the most debated results of observational cosmology in recent times. The cosmological 21 cm has long been proposed to be a powerful probe for observing the early Universe and tracing its evolution over cosmic time. Even though the science case is well established, measurement challenges posed on the technical ground are not fully understood to the level of claiming a successful detection. EDGES’s detection has naturally motivated a number of experimental attempts worldwide to corroborate the findings. In this paper, we present a precision cross-correlation spectrometer HYPEREION purpose-designed for a precision radio background measurement between 50–120 MHz to detect the absorption profile reported by the EDGES experiment. HYPEREION implements a pre-correlation signal processing technique that self-calibrates any spurious additive contamination from within the system and delivers a differential measurement of the sky spectrum and a reference thermal load internal to the system. This ensures an unambiguous ‘zero-point’ of absolute calibration of the purported absorption profile. We present the system design, measurement equations of the ideal system, systematic effects in the real system, and finally, an assessment of the real system output for the detection of the absorption profile at 78 MHz in the continuum radio background spectrum.

ABSTRACT IMPACT: This is the first examination of risk factors for prolonged opioid use after an ICU stay and will inform efforts to strengthen prescribing guidelines and care transition models for patients after critical illness. OBJECTIVES/GOALS: The majority of patients in intensive care units (ICU) receive opioids during admission, and up to 25% receive a prescription at discharge. However, transitions of care and prolonged use after discharge remain unknown. We aim to characterize risk factors for prolonged opioid use after an ICU stay. METHODS/STUDY POPULATION: A retrospective study using insurance claims from Optum Clinformatics ®Data Mart was conducted for opioid-naive adult patients (18-64 years) with an ICU admission from 2010 to 2019. The primary outcome was new persistent opioid use, defined as a continued prescription fill 91-180 days after discharge, in addition to a fill in the first 90 days. The primary exposure was an opioid fill at discharge. The ICU admission was characterized using the Clinical Classification System from the Agency of Healthcare Research and Quality, based on patients’primary diagnosis code. Diagnoses were combined into 11 groups highlighting the affected organ system/mechanism of injury. Logistic regression evaluated the associations of patient demographic and clinical characteristics with the probability of persistent opioid use. RESULTS/ANTICIPATED RESULTS: In this cohort of 90,721 patients discharged from the ICU, 3.3% continued to fill opioids at 6 months. An opioid prescription fill (OR 3.1; 95% CI 28 - 3.3) and benzodiazepine prescription fill (OR 1.6; 95% CI 1.4 - 1.8) within 3 days of ICU discharge were each significantly associated with the development of new persistent opioid use. Patient diagnosis groups of Musculoskeletal/Trauma (OR 2.3; 95% CI 2.0 - 2.6), Neoplasms (OR 1.6; 95% CI 1.5 - 1.9), and GI/Hepatobiliary (OR 1.5; 95% CI 1.3 - 1.8) were significantly more likely to develop new persistent use when compared to the Cardiovascular diagnosis group. DISCUSSION/SIGNIFICANCE OF FINDINGS: Opioid prescriptions at discharge after an ICU stay increase the odds of prolonged opioid use. These results will inform efforts to strengthen prescribing guidelines and care models after a critical illness. Further work will characterize the trajectory of prescribing and patient exposure to high-risk prescribing after ICU discharge.