The Oldest Mineralized Bryozoan? A Possible Palaeostomate in the Lower Cambrian of Nevada, USA

All skeletal marine invertebrate phyla appeared during the Cambrian explosion, except for Bryozoa with mineralized skeletons, which first appear in the Early Ordovician. However, the skeletal diversity of Early Ordovician bryozoans suggests a preceding interval of diversification. We report a possible earliest occurrence of palaeostomate bryozoans in limestones of the Cambrian Age 4 Harkless Formation, western United States. Following recent interpretations of the early Cambrian Protomelission as a soft-bodied bryozoan, our findings add to the evidence of early Cambrian roots for the Bryozoa. The Harkless fossils resemble some esthonioporate and cystoporate bryozoans, showing a radiating pattern of densely packed tubes of the same diameter and cross-sectional shape. Further, they show partitioning of new individuals from parent tubes through the formation of a separate wall, a characteristic of interzooecial budding in bryozoans. If confirmed as bryozoans, these fossils would push back the appearance of mineralized skeletons in this phylum by ~30 million years and impact interpretations of their evolution

Risk aversion in the use of complex kidneys in paired exchange programs: Opportunities for even more transplants?

This retrospective review of the largest United States kidney exchange reports characteristics, utilization, and recipient outcomes of kidneys with simple compared to complex anatomy and extrapolates reluctance to accept these kidneys. Of 3105 transplants performed, only 12.8% were right kidneys and 23.1% had multiple renal arteries. 59.3% of centers used fewer right kidneys than expected and 12.1% transplanted zero right kidneys or kidneys with more than 1 artery. Five centers transplanted a third of these kidneys (35.8% of right kidneys and 36.7% of kidneys with multiple renal arteries). 22.5% and 25.5% of centers currently will not entertain a match offer for a left or right kidney with more than one artery, respectively. There were no significant differences in all-cause graft failure or death-censored graft loss for kidneys with multiple arteries, and a very small increased risk of graft failure for right kidneys versus left of limited clinical relevance for most recipients. Kidneys with complex anatomy can be used with excellent outcomes at many centers. Variation in use (lack of demand) for these kidneys reduces the number of transplants, so systems to facilitate use could increase demand. We cannot know how many donors are turned away because perceived demand is limited.Wiley Read-and-Publish Agreemen

Development and Assessment of a Systematic Approach for Detecting Disparities in Surgical Access

IMPORTANCE: Although optimal access is accepted as the key to quality care, an accepted methodology to ascertain potential disparities in surgical access has not been defined. OBJECTIVE: To develop a systematic approach to detect surgical access disparities. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study used publicly available data from the Health Cost and Utilization Project State Inpatient Database from 2016. Using the surgical rate observed in the 5 highest-ranked counties (HRCs), the expected surgical rate in the 5 lowest-ranked counties (LRCs) in North Carolina were calculated. Patients 18 years and older who underwent an inpatient general surgery procedure and patients who underwent emergency inpatient cholecystectomy, herniorrhaphy, or bariatric surgery in 2016 were included. Data were collected from January to December 2016, and data were analyzed from March to July 2020. EXPOSURES: Health outcome county rank as defined by the Robert Wood Johnson Foundation. MAIN OUTCOMES AND MEASURES: The primary outcome was the proportional surgical ratio (PSR), which was the disparity in surgical access defined as the observed number of surgical procedures in the 5 LRCs relative to the expected number of procedures using the 5 HRCs as the standardized reference population. RESULTS: In 2016, approximately 1.9 million adults lived in the 5 HRCs, while approximately 246 854 lived in the 5 LRCs. A total of 28 924 inpatient general surgical procedures were performed, with 4521 being performed in those living in the 5 LRCs and 24 403 in those living in the 5 HRCs. The rate of general surgery in the 5 HRCs was 13.09 procedures per 1000 population. Using the 5 HRCs as the reference, the PSR for the 5 LRCs was 1.40 (95% CI, 1.35-1.44). For emergent/urgent cholecystectomy, the PSR for the 5 LRCs was 2.26 (95% CI, 2.02-2.51), and the PSR for emergent/urgent herniorrhaphy was 1.83 (95% CI, 1.33-2.45). Age-adjusted rate of obesity (body mass index [calculated as weight in kilograms divided by height in meters squared] greater than 30), on average, was 36.6% (SD, 3.4) in the 5 LRCs vs 25.4% (SD, 4.6) in the 5 HRCs (P = .002). The rate of bariatric surgery in the 5 HRCs was 33.07 per 10 000 population with obesity. For the 5 LRCs, the PSR was 0.60 (95% CI, 0.51-0.69). CONCLUSIONS AND RELEVANCE: The PSR is a systematic approach to define potential disparities in surgical access and should be useful for identifying, investigating, and monitoring interventions intended to mitigate disparities in surgical access that effects the health of vulnerable populations

SUMMARY OF THE APDA FUEL DEVELOPMENT PROGRAMS

A summary is presented of the development status, through 1960, of work done on: Core A, the U--10 wt.% Mo fuel and U--3 wt.% Mo blanket, and Core B, the U0/sub 2/--SS cermet and the UO/sub 2/ axial blanket for the Fermi Fast Breeder Reactor; advanced fast reactor fuels; and paste fuels. (B.O.G.

Formally Verified Synthesis of Combinational {CMOS} Circuits

We present a system for simultaneously synthesizing and proving correct CMOS implementations of combinational circuits. Our system, developed within the Nuprl proof development system, is based on a set of transformation rules that generate CMOS implementations from their logical specifications. Our research differs from previous work in three important ways: our rules are rigorously proven with respect to a formal transistor model, our transformation rules admit the synthesis of both pass transistor and series/parallel networks, and our implementation produces a human readable proof along with each circuit it synthesizes