Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Arthroscopic Sternoclavicular Joint Resection Arthroplasty: A Technical Note and Illustrated Case Report

Open resection arthroplasty of the sternoclavicular (SC) joint has historically provided good long-term results in patients with symptomatic osteoarthritis of the SC joint. However, the procedure is rarely performed because of the risk of injury to vital mediastinal structures and concern regarding postoperative joint instability. Arthroscopic decompression of the SC joint has therefore emerged as a potential treatment option because of many recognized advantages including minimal tissue dissection, maintenance of joint stability, avoidance of posterior SC joint dissection, expeditious recovery, and improved cosmesis. There are, however, safety concerns given the proximity of neurovascular structures. In this article we demonstrate a technique for arthroscopic SC joint resection arthroplasty in a 26-year-old active man with bilateral, painful, idiopathic degenerative SC joint osteoarthritis. This case also highlights the pearls and pitfalls of arthroscopic resection arthroplasty for the SC joint. There were no perioperative complications. Four months postoperatively, the patient had returned to full activities, including weightlifting, without pain or evidence of SC joint instability. One year postoperatively, the patient showed substantial improvements in the American Shoulder and Elbow Surgeons score; Single Assessment Numeric Evaluation score; Quick Disabilities of the Arm, Shoulder and Hand score; and Short Form 12 Physical Component Summary score over preoperative baseline values

First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

International audienceSpinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signal-to-noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far