Muddy and sandy sediments have different physical properties. Muds are cohesive elastic solids, whereas granular beach sands are non-cohesive porous media. Infaunal organisms such as worms that burrow through sediments therefore face different mechanical challenges that potentially lead to a variety of burrowing strategies and morphologies. In this study we compared three morphologically distinct polychaete species representing different clades in the family Orbiniidae and related differences in their burrowing behaviors and morphologies to their natural environments (mud or sand). Worms burrowed in transparent analogs for muds and sands, and kinematic analysis showed differences both among species and between materials. Leitoscoloplos pugettensis lives in mud and burrows by fracture, using its pointed head to concentrate stress at the tip of the burrow. Naineris dendritica lives in sand and uses its broader head that fluctuates in width over a burrowing cycle to decrease backward slipping in sand, potentially preventing burrow collapse. Orbinia johnsoni lives in sand and uses internal body expansions to pack sand grains, another mechanism to prevent burrow collapse. By combining data from species and materials to obtain a broad range of burrowing velocities, we show that burrowing worms control their velocity by increasing or decreasing their burrowing frequency rather than by altering cycle distance as shown previously for crawling earthworms. This study demonstrates how fairly small evolutionary divergences in morphologies and behaviors facilitate locomotion in environments with different physical constraints.

ObjectiveTo evaluate single-pass loop electrosurgical excision procedure (LEEP-SP) versus LEEP with top hat (LEEP-TH) in terms of treatment failure defined as high-grade squamous intraepithelial lesion (HSIL) cytology within 2 years’ follow-up.MethodsThis single-institution cohort study used a prospectively collected cervical dysplasia database including all patients who underwent LEEP-SP or LEEP-TH for biopsy-proven cervical intraepithelial neoplasia between 2005 and 2019.ResultsOf 340 patients included, 178 underwent LEEP-SP and 162 LEEP-TH. The LEEP-TH patients were more likely to be older (mean age, 40.4 vs 36.5 years; p < .001) and have a positive preprocedure endocervical sampling (68.5% vs 11.8%; p < .001). Positive margins were found in 23 LEEP-SP (12.9%) and in 25 LEEP-TH (15.4%; p = .507). There was no significant difference in depth of excision between LEEP-SP (13.21 ± 23.19 mm) and LEEP-TH (17.37 ± 28.26 mm; p = .138). At 2 years, there was no difference in the rates of HSIL cytology (5.2% vs 6.3%; p = .698), any positive human papillomavirus test, or HSIL cytology (25% vs 15%; p = .284). The 57 patients undergoing repeat excision were more likely to be older (mean age, 40.95 vs 37.52 years; p = .023), have had a LEEP-TH (26.3% vs 73.7%; p < .001), and have initial cytologic HSIL (64.9% vs 35.0%; p < .001).ConclusionsIn this single-institution study, there is no difference in the rate of recurrent HSIL in patients undergoing LEEP-SP versus LEEP-TH. A LEEP-TH may have limited additional benefit over a LEEP-SP in the treatment of cervical HSIL.

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