Reconstructing the feeding ecology of Cambrian sponge reefs: the case for active suspension feeding in Archaeocyatha.

Sponge-grade Archaeocyatha were early Cambrian biomineralizing metazoans that constructed reefs globally. Despite decades of research, many facets of archaeocyath palaeobiology remain unclear, making it difficult to reconstruct the palaeoecology of Cambrian reef ecosystems. Of specific interest is how these organisms fed; previous experimental studies have suggested that archaeocyaths functioned as passive suspension feeders relying on ambient currents to transport nutrient-rich water into their central cavities. Here, we test this hypothesis using computational fluid dynamics (CFD) simulations of digital models of select archaeocyath species. Our results demonstrate that, given a range of plausible current velocities, there was very little fluid circulation through the skeleton, suggesting obligate passive suspension feeding was unlikely. Comparing our simulation data with exhalent velocities collected from extant sponges, we infer an active suspension feeding lifestyle for archaeocyaths. The combination of active suspension feeding and biomineralization in Archaeocyatha may have facilitated the creation of modern metazoan reef ecosystems.

National Trends in Imaging Rates for Eye-Related Emergency Department Visits in the United States.

PURPOSE: To identify nationwide trends and factors associated with advanced imaging (computed tomography [CT] and magnetic resonance imaging [MRI]) use for eye-related emergency department (ED) visits. DESIGN: Retrospective, trend study. METHODS: Setting: National Hospital Ambulatory Medical Care Survey 2007-2015. PATIENT POPULATION: Eye-related ED patients who underwent CT or MRI. MAIN OUTCOME MEASURE(S): Population-based CT/MR imaging rates and independent factors associated with imaging. RESULTS: An estimated 7 million eye-related ED visits occurred between 2007 and 2015. Adjusted for annual eye-related ED visits, the rate of imaging use rose 94%, from 121.7 per 1,000 eye-related ED visits in 2007 to 236.0 per 1,000 eye-related ED visits in 2015. Visual disturbances, contusion of the eye and/or adnexa, open globes and open wounds of ocular adnexa, diplopia, superficial corneal and/or conjunctival injuries, and orbital fractures accounted for 73.2% of all visits where imaging was performed. On multivariable analysis, older patients (odds ratio [OR] = 1.02, 95% confidence interval [CI] 1.01-1.03) and females (OR=2.07, 95% CI 1.18-3.63) were more likely to undergo imaging than younger patients and males. Imaging was also more likely to be performed for Medicare beneficiaries (OR=2.12, 95% CI 1.08-4.15) than for privately insured patients. Patients who were admitted to the hospital were 6 times more likely (OR=6.39, 95% CI 2.04-20.0) to undergo imaging than those who were not admitted. CONCLUSIONS: Advanced imaging for eye-related ED visits has escalated at a higher rate than ED visits for eye complaints. Future studies to develop evidence-based algorithms for use of CT/MR imaging for eye complaints that can help balance benefits against financial costs and health risk are warranted.