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The Hamburg meteorite fell on January 16, 2018, near Hamburg, Michigan, after a fireball event widely observed in the U.S. Midwest and in Ontario, Canada. Several fragments fell onto frozen surfaces of lakes and, thanks to weather radar data, were recovered days after the fall. The studied rock fragments show no or little signs of terrestrial weathering. Here, we present the initial results from an international consortium study to describe the fall, characterize the meteorite, and probe the collision history of Hamburg. About 1kg of recovered meteorites was initially reported. Petrology, mineral chemistry, trace element and organic chemistry, and O and Cr isotopic compositions are characteristic of H4 chondrites. Cosmic ray exposure ages based on cosmogenic 3He, 21Ne, and 38Ar are ~12Ma, and roughly agree with each other. Noble gas data as well as the cosmogenic 10Be concentration point to a small 40-60cm diameter meteoroid. An 40Ar-39Ar age of 4532±24Ma indicates no major impact event occurring later in its evolutionary history, consistent with data of other H4 chondrites. Microanalyses of phosphates with LA-ICPMS give an average Pb-Pb age of 4549±36Ma. This is in good agreement with the average SIMS Pb-Pb phosphate age of 4535.3±9.5Ma and U-Pb Concordia age of 4535±10Ma. The weighted average age of 4541.6±9.5Ma reflects the metamorphic phosphate crystallization age after parent body formation in the early solar system.

Introduction Computerized tomography (CT) scans are the mainstay of diagnostic imaging in blunt trauma. Particularly in pediatric trauma, utilization of CT scans has increased exponentially in recent years. Concerns regarding radiation exposure to this vulnerable population have resulted in increased scrutiny of practice. What is not known is if liberal imaging practices decrease length of stay by eliminating the need for clinical observation, and the impact of false-positive rates from liberal use of CT scanning on clinical outcomes. Methods Medical records from a nonaccredited pediatric trauma center with a practice of liberal imaging were reviewed over a 2-year period. Total CT scans obtained were recorded, in addition to length of stay, age, and Injury Severity Score (ISS). Rates of clinically significant imaging findings were recorded, as were false positive findings and complications of imaging. Results Out of 735 children, 58% underwent CT scanning, and if scanned, received an average of 2.4 studies. Clinically significant findings were documented in 20% of head CTs, 2% of cervical spine CTs, 3.5% of chest CTs, 24% of facial CTs, and 14.7% of abdominal CTs. False-positive findings were found in 1.5% of head CTs, 1.2% of cervical spine CTs, 2.4% of chest CTs, and 2.5% of abdominal CTs. Liberal CT scanning was not associated with decreased length of stay. In contrast, obtaining CT scans on more than 4 body regions was independently predictive of longer length of stay, independent of ISS. Conclusions False-positive rates of CT scans for trauma were low in this cohort. However, when scanning the cervical spine or the chest, for every 2 clinically significant findings obtained, there was at least one false positive result, calling into question the practice of liberal imaging of these regions. Liberal utilization of CT scan did not allow for more rapid discharge home, and for more than 4 CTs was independently associated with longer hospital stay.

PURPOSE To compare the expression of CD73 in indolent nodular basal cell carcinomas and cutaneous lesions that invade the orbit. METHODS Immunohistochemical staining for CD73 was performed on nodular basal cell carcinomas and invasive basal cell carcinomas. The numbers of positively staining cells were counted across 5 consecutive ×40 microscopic fields, and a statistical comparison was performed via a dedicated computerized software package. RESULTS Ten control specimens and 11 invasive tumors were analyzed. In nodular basal cell carcinomas, the mean number of positively staining cells was 0.72/×40 field (standard deviation = 0.80 cells/×40 field), whereas invasive tumors demonstrated a mean of 6.53 positive staining cells/×40 field (standard deviation = 3.33 cells/×40 field). This difference was statistically significant (p = 0.0002). CONCLUSIONS CD73 is enriched in orbital invasion of cutaneous carcinomas. This checkpoint may represent an important target for therapeutic management of these lesions. Immunotherapeutic agents that have been designed to treat other neoplasms may decrease the requirement for orbital exenteration in this clinical scenario.