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We describe an ultrafast optics laboratory comprising a mode-locked erbium fiber laser, autocorrelation measurements, and a free-space parallel grating dispersion compensation apparatus. The gain spectrum of Er fiber provides a broad bandwidth capable of supporting sub-100 fs pulses centered near a wavelength of 1550 nm. The fiber laser design used here produces a train of pulses at a repetition rate of 55 MHz with pulse duration as short as 108 fs. The pulse duration is measured with a homebuilt autocorrelator using a simple Michelson interferometer that takes advantage of the two-photon nonlinear response of a common silicon photodiode. To compensate for temporal stretching of the short pulse due to group velocity dispersion in the fiber, an apparatus based on a pair of parallel gratings is used for pulse compression. A detailed part that lists in the supplementary material includes previously owned and common parts used by the telecommunications industry, which helps decrease costs of the laboratory. This provides a cost-effective way to introduce the principles of ultrafast optics to undergraduate laboratories.

Objectives This study sought to investigate the factors associated with repeat infection following lead extraction procedures. Background Although lead extraction is an essential therapy for patients with cardiovascular implantable electronic device (CIED) infection, repeat infection still occurs in some patients. Methods The authors reviewed data for consecutive patients who underwent extraction of infected CIEDs from August 2003 to May 2019. Repeat infection was defined as infective endocarditis, sepsis with no alternative focus, or pocket infection after extraction of infected CIEDs. Results Extraction of infected CIEDs was performed in 496 patients. The most commonly implicated pathogen was Staphylococcus aureus (n = 188). In 449 patients (90.5%), all leads were completely extracted using only transvenous techniques. Thirty-three patients (6.7%) underwent surgical lead extraction, and 14 (2.8%) had retained leads or lead components. After a median follow-up of 352 [40 to 1,255] days after CIED extraction, 144 patients (29.0%) died. Repeat infection occurred in 47 patients (9.5%) with the median time from the extraction to repeat infection of 103 [45 to 214] days. In multivariable analysis, presence of a left ventricular assist device, younger age at extraction, and S. aureus infection were independent predictors of repeat infection. Additionally, chronic kidney disease, congestive heart failure, presence of septic emboli, S. aureus infection, and occurrence of major complications were independent predictors of increased mortality. Conclusions Patients with S. aureus infection have a high risk of repeat infection and poor prognosis after CIED extraction. Repeat infection is also predicted by younger age and the presence of a left ventricular assist device, whereas mortality was predicted by congestive heart failure, chronic kidney disease, and septic emboli.

We discuss the design of quantum hybrid inertial sensor that combines an optomechanical inertial sensor with the retroreflector of a cold atom interferometer. This sensor fusion approach provides absolute and high-accuracy measurements with cold atom interferometers, while utilizing the optomechanical inertial sensor at frequencies above the repetition rate of the atom interferometer. This improves the overall measurement bandwidth as well as the robustness and field deployment capabilities of these systems. We evaluate which parameters yield an optimal acceleration sensitivity, from which we anticipate a noise floor at nano- g levels from DC to 1 kHz.

This article describes a service learning project implemented midsemester in response to the September 11, 2001, attacks. The project applied course topics while allowing students to positively channel their anxiety. Students developed and implemented a community-wide effort to collect care packages for U.S. troops deployed to Afghanistan. The article presents the project’s evolution, successes, and problems. The pros and cons of service learning through changing a course midsemester are also discussed. This project description may be instructive to readers who are contemplating service learning class projects. It should also be of interest to instructors who sense the need to change a course midsemester.

Point Marion Lock was designed to replace an existing navigation lock that has been in service on the Monongahela River near the Pennsylvania-West Virginia border for some 67 years. As a result of the close proximity of the planned excavation for the new lock, the land wall of the existing lock required extensive stabilization to permit it to be utilized as the river arm of the project cofferdam. Installation of 471 prestressed rock anchors was closely linked with each progressive stage of soil and rock excavation required to build the new lock. Adverse geologic conditions affected cofferdam stability in that the land wall of the existing operating lock was founded on weak sedimentary rocks exhibiting very low shear strength. Critical to the successful performance of the cofferdam was the design and installation of an extensive instrumentation program. A vast array of movement detection systems including inclinometers, alignment pins, shear strips, tilt plates and load cells were interfaced with both on-site and off-site computers to provide real-time monitoring of cofferdam performance throughout the excavation process. Data from instrumentation yielded invaluable information needed to make necessary adjustments in on-going construction activities including excavation and rock anchor installation.