Incline and decline running alters joint moment contributions but not peak support moments in individuals with an anterior cruciate ligament reconstruction and controls.

Individuals with an anterior cruciate ligament reconstruction (ACLR) commonly exhibit altered gait patterns, potentially contributing to an increased risk of osteoarthritis (OA). Joint moment contributions (JMCs) and support moments during incline and decline running are unknown in healthy young adults and individuals with an ACLR. Understanding these conditional joint-level changes could explain the increased incidence of OA that develops in the long term. Therefore, this knowledge may provide insight into the rehabilitation and prevention of OA development. We aimed to identify the interlimb and between-group differences in peak support moments and subsequent peak ankle, knee, and hip JMCs between individuals with an ACLR and matched controls during different sloped running conditions. A total of 17 individuals with unilateral ACLR and 17 healthy individuals who were matched based on sex, height, and mass participated in this study. The participants ran on an instrumented treadmill at an incline of 4°, decline of 4°, incline of 10°, and decline of 10°. The last 10 strides of each condition were used to compare the whole-stance phase support moments and JMCs between limbs, ACLR, and control groups and across conditions. No differences in JMCs were identified between limbs or between the ACLR and healthy control groups across all conditions. Support moments did not change among the different sloped conditions, but JMCs significantly changed. Specifically, ankle and knee JMCs decreased and increased by 30% and 33% from an incline of 10° to a decline of 10° running. Here, the lower extremities can redistribute mechanics across the ankle, knee, and hip while maintaining consistent support moments during incline and decline running. Our data provide evidence that those with an ACLR do not exhibit significant alterations in joint contributions while running on sloped conditions compared to the matched controls. Our findings inform future research interested in understanding the relationship between sloped running mechanics and the incidence of deleterious acute or chronic problems in people with an ACLR.

Pressurized fluid damping of nanoelectromechanical systems.

Interactions of nanoscale structures with fluids are of current interest both in the elucidation of fluid dynamics at these small scales, and in determining the ultimate performance of nanoelectromechanical systems outside of vacuum. We present a comprehensive study of nanomechanical damping in three gases (He, N2, CO2), and liquid CO2. Resonant dynamics in multiple devices of varying size and frequency is measured over 10 decades of pressure (1 mPa-20 MPa) using time-domain stroboscopic optical interferometry. The wide pressure range allows full exploration of the regions of validity of Newtonian and non-Newtonian flow damping models. Observing free molecular flow behavior extending above 1 atm, we find a fluid relaxation time model to be valid throughout, but not beyond, the non-Newtonian regime, and a Newtonian flow vibrating spheres model to be valid in the viscous limit.

A simple cell for the analysis of nanoelectromechanical systems under gas pressure.

A simple yet versatile apparatus for optical microscopy investigations of solid-state devices under high gas pressures is presented. Interchangeable high-grade sapphire windows with different thicknesses allow variable choice of trade-off between the maximum operating pressure and maximum spatial resolution. The capabilities of this compact chamber were tested by performing stroboscopic optical interferometry on nanoelectromechanical systems (NEMSs) under capacitive excitation. With a 1.7 mm thick sapphire window, the cell is safe to operate at pressures ranging from vacuum to 5 MPa. Minimal optical wavefront distortion allows NEMSs with linear dimensions of 0.1x1.6 microm(2) to be explored. For a sapphire window with a maximum thickness of 6 mm, the safe operating pressure increases up to an estimated 60 MPa; however, the increasing distortions inhibit signal from NEMSs smaller than approximately 0.5x1 microm(2). The cell can be used for confocal microscopy, microphotoluminescence and electroluminescence, light scattering spectroscopy, and reflectivity. The light weight and compact design of the chamber allow mounting on a precision piezomotion control stage or inside a volume tight apparatus such as cryostats.

The principles of mohs micrographic surgery for cutaneous neoplasia.

Skin cancer is the most common form of cancer, and although its most common forms are rarely life threatening, the morbidity of this disease is substantial, especially in the southern regions of the United States. Mohs micrographic surgery (MMS) is a precise form of microscopically controlled excisional surgery created in the US but currently practiced worldwide and used to treat various cutaneous carcinomas. The history, technique, indications, and recurrence rates of MMS are discussed to allow the practicing physician to understand the specific instances when patients will best benefit from this procedure.

The crisscross tie-over tacking suture revisited.

BACKGROUND: Deep pexing or tacking sutures can be useful in certain situations encountered in dermatologic surgery when surface concavities require recreation. OBJECTIVE: To examine and discuss some pexing suture techniques that have been described in the past and to outline alternatives. METHODS: Pexing suture techniques are presented in a series of schematic diagrams that follow. RESULTS: The crisscross tie-over tacking suture as described by Albertini is shown as well as a modification that theoretically lessens complication risk. The pexing buried vertical mattress suture is then presented. CONCLUSION: The dermatologic surgeon may find pexing or deep tacking sutures helpful in selected cases.

Basosquamous carcinoma.

BACKGROUND: Basosquamous carcinoma (BSC) is a rare cutaneous tumor that has been poorly described in the dermatologic literature. It has been depicted as an aggressive tumor with a high incidence of distant metastasis. OBJECTIVE: To examine the average extent of local tissue invasion and presence of distant metastases in cases of BSC compared with those of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). METHODS: One thousand consecutive Mohs surgery cases performed between January 1993 and May 1995 at the Oschner Clinic in New Orleans, Louisiana, for histologically confirmed BCC, SCC, and BSC were reviewed. Each case was retrospectively evaluated for tumor type, anatomic location, number of Mohs stages performed, and presence of metastases at the time of surgery, as determined by chest radiograph. RESULTS: Seven hundred forty-five BCCs, 228 SCCs, and 27 BSCs (1,000 tumors total) were treated in 580 patients. The average number of stages required for clear margins in cases of BCC, SCC, and BSC was 1.62, 1.51, and 2.00, respectively. The prevalence of metastasis was 0.87% for SCC and 7.4% for BSC, which was statistically significant (P<0.001). CONCLUSION: In this retrospective study, BSCs displayed tissue invasion similar to that of BCC or SCC but had a higher frequency of pulmonary metastasis than SCC.