Walter Neal Simmons

Journal article Am Surg · August 2022 The COVID-19 pandemic has resulted in the exposure of many surgeons and healthcare providers (HCPs) to disease given high patient loads and limited availability of negative pressure rooms. For these reasons we pursued the development of a portable patient ... Full text Link to item Cite

Evaluation of a Novel Single-Use Flexible Ureteroscope.

Journal article J Endourol · June 2021 Introduction: A novel single-use flexible ureteroscope promises the optical characteristics and maneuverability of a reusable fourth-generation flexible ureteroscope. In this study, the LithoVue Single-Use Digital flexible ureteroscope was directly compare ... Full text Link to item Cite

An in vitro evaluation of laser settings and location in the efficiency of the popcorn effect.

Journal article Urolithiasis · August 2019 To examine different locations and laser settings' effects on the efficiency of the "popcorn" method of laser lithotripsy, which consists of placing the laser in a group of small stones and firing continuously to break them into smaller particles. Pre-frag ... Full text Link to item Cite

Let's Get to the Point: Comparing Insertion Characteristics and Scope Damage of Flat-Tip and Ball-Tip Holmium Laser Fibers.

Journal article J Endourol · January 2019 INTRODUCTION: A ball-tip holmium laser fiber (TracTip; Boston Scientific) has been developed to theoretically reduce damaging friction forces generated within a ureteroscope working channel. We compared the insertional forces and damage with a ureteroscope ... Full text Link to item Cite

Dusting Efficiency of the Moses Holmium Laser: An Automated In Vitro Assessment.

Journal article J Endourol · December 2018 INTRODUCTION: Moses technology is a novel Holmium:YAG laser system designed to minimize stone retropulsion and improve stone ablation when the laser is not in direct contact with the stone. Our aim was to assess the efficiency of Moses technology relative ... Full text Link to item Cite

In Vitro Comparison of a Novel Single Probe Dual-Energy Lithotripter to Current Devices.

Journal article J Endourol · June 2018 PURPOSE: The LithoClast Trilogy is a novel single probe, dual-energy lithotripter with ultrasonic (US) vibration and electromagnetic impact forces. ShockPulse and LithoClast Select are existing lithotripters that also use a combination of US and mechanical ... Full text Link to item Cite

Effect of Laser Settings and Irrigation Rates on Ureteral Temperature During Holmium Laser Lithotripsy, an In Vitro Model.

Journal article J Endourol · January 2018 PURPOSE: Ureteroscopic laser lithotripsy requires irrigation for adequate visualization and temperature control during treatment of ureteral stones. However, there are little data on how different irrigation and laser settings affect the ureteral wall and ... Full text Link to item Cite

Next-Generation Single-Use Ureteroscopes: An In Vitro Comparison.

Journal article J Endourol · December 2017 INTRODUCTION: Single-use ureteroscopes have been gaining popularity in recent years. We compare the optics, deflection, and irrigation flow of two novel single-use flexible ureteroscopes-the YC-FR-A and the NeoFlex-with contemporary reusable and single-use ... Full text Link to item Cite

Variable Pulse Duration From a New Holmium:YAG Laser: The Effect on Stone Comminution, Fiber Tip Degradation, and Retropulsion in a Dusting Model.

Journal article Urology · May 2017 OBJECTIVE: To more clearly define the efficiency and potential benefits of variable pulse-width laser technology for ureteroscopic lithotripsy, we performed comparative in vitro evaluations assessing stone comminution, laser fiber tip degradation, and ston ... Full text Link to item Cite

Comparison of Broad vs Narrow Focal Width Lithotripter Fields.

Journal article J Endourol · May 2017 OBJECTIVE: To investigate the impact of lithotripter focal width on stone fragmentation. MATERIALS AND METHODS: A modified reflector was used to reduce -6 dB beam size of the HM3 lithotripter, while increasing concomitantly peak pressure. Fragmentation in ... Full text Link to item Cite

Comparison of the Nanopulse Lithotripter to the Holmium Laser: Stone Fragmentation Efficiency and Impact on Flexible Ureteroscope Deflection and Flow.

Journal article J Endourol · November 2016 INTRODUCTION: The Nanopulse Lithotripter (NPL; Lithotech Medical, Israel) is a novel intracorporeal device that uses a nanosecond duration electrical discharge through a reusable flexible coaxial probe to endoscopically fragment urinary stones. This device ... Full text Link to item Cite

Spectral descriptors for bulk metallic glasses based on the thermodynamics of competing crystalline phases.

Journal article Nature communications · August 2016 Metallic glasses attract considerable interest due to their unique combination of superb properties and processability. Predicting their formation from known alloy parameters remains the major hindrance to the discovery of new systems. Here, we propose a d ... Full text Cite

Evaluation of Novel Ball-Tip Holmium Laser Fiber: Impact on Ureteroscope Performance and Fragmentation Efficiency.

Journal article J Endourol · February 2016 PURPOSE: A novel ball tip (BT) holmium laser fiber has recently been developed, which features a modified rounded tip. The modification is purported to aid in insertion and minimize damage to the ureteroscope working channel. We evaluated this laser fiber ... Full text Link to item Cite

Improving the lens design and performance of a contemporary electromagnetic shock wave lithotripter.

Journal article Proc Natl Acad Sci U S A · April 1, 2014 The efficiency of shock wave lithotripsy (SWL), a noninvasive first-line therapy for millions of nephrolithiasis patients, has not improved substantially in the past two decades, especially in regard to stone clearance. Here, we report a new acoustic lens ... Full text Open Access Link to item Cite

Assessment of a modified acoustic lens for electromagnetic shock wave lithotripters in a swine model.

Journal article J Urol · September 2013 PURPOSE: The acoustic lens of the Modularis electromagnetic shock wave lithotripter (Siemens, Malvern, Pennsylvania) was modified to produce a pressure waveform and focal zone more closely resembling that of the original HM3 device (Dornier Medtech, Wessli ... Full text Link to item Cite

Experimentally validated multiphysics computational model of focusing and shock wave formation in an electromagnetic lithotripter.

Journal article The Journal of the Acoustical Society of America · August 2013 A multiphysics computational model of the focusing of an acoustic pulse and subsequent shock wave formation that occurs during extracorporeal shock wave lithotripsy is presented. In the electromagnetic lithotripter modeled in this work the focusing is achi ... Full text Cite

Increasing dwell time of mitomycin C in the upper tract with a reverse thermosensitive polymer.

Journal article J Endourol · March 2013 UNLABELLED: Abstract Background and Purpose: Topical chemotherapy for urothelial cancer is dependent on adequate contact time of the chemotherapeutic agent with the urothelium. To date, there has not been a reliable method of maintaining this contact for r ... Full text Link to item Cite

In-vitro assessment of a new portable ballistic lithotripter with percutaneous and ureteroscopic models.

Journal article J Endourol · November 2012 BACKGROUND AND PURPOSE: The EMS Swiss LithoBreaker is a new, portable, electrokinetic lithotripter. We compared its tip velocity and displacement characteristics with a handheld, pneumatic lithotripter LMA StoneBreaker.™ We also evaluated fragmentation eff ... Full text Link to item Cite

Optical performance comparison of deflectable laparoscopes for laparoendoscopic single-site surgery.

Journal article J Endourol · October 2012 BACKGROUND AND PURPOSE: Flexible working angles and fine optical visualization are major requisite factors in performing laparoendoscopic single-site (LESS) urologic procedures. Multiple mechanical design approaches have been used to develop deflectable la ... Full text Link to item Cite

Organ-specific radiation dose rates and effective dose rates during percutaneous nephrolithotomy.

Journal article J Endourol · May 2012 BACKGROUND AND PURPOSE: Radiation exposure during medical procedures continues to be an increasing concern for physicians and patients. We determined organ-specific dose rates and calculated effective dose rates during right and left percutaneous nephrolit ... Full text Link to item Cite

Carbon diffusion in lanthanum erbium carbide stabilized in the cubic fluorite structure

Journal article Journal of Phase Equilibria and Diffusion · April 1, 2012 Lanthanum erbium carbide, La 0.5-Er 0.5C 2, a salt-like carbide with a cubic fluorite phase structure, has been produced from 13C, allowing carbon diffusion rate to be determined using 12C. Carbon in s ... Full text Cite

A comparison of light spot hydrophone and fiber optic probe hydrophone for lithotripter field characterization.

Journal article Rev Sci Instrum · January 2012 The performance of a newly developed light spot hydrophone (LSHD) in lithotripter field characterization was compared to that of the fiber optic probe hydrophone (FOPH). Pressure waveforms produced by a stable electromagnetic shock wave source were measure ... Full text Link to item Cite

A new acoustic lens design for electromagnetic shock wave lithotripters

Journal article Aip Conference Proceedings · October 13, 2011 The 3rd-generation electromagnetic (EM) shock wave lithotripters often have narrow focal width and high peak pressure compared to the original Dornier HM-3. In addition, the pressure waveform produced by a typical EM lithotripter has a secondary ... Full text Cite

Optimization of treatment strategy used during shockwave lithotripsy to maximize stone fragmentation efficiency.

Journal article J Endourol · September 2011 BACKGROUND AND PURPOSE: Previous studies have demonstrated that treatment strategy plays a critical role in ensuring maximum stone fragmentation during shockwave lithotripsy (SWL). We aimed to develop an optimal treatment strategy in SWL to produce maximum ... Full text Open Access Link to item Cite

Pathologic evaluation of hemostatic agents in percutaneous nephrolithotomy tracts in a porcine model.

Journal article J Endourol · August 2011 BACKGROUND AND PURPOSE: Hemostatic agents have been suggested as an adjunct for tubeless percutaneous nephrolithotomy (PCNL). We pathologically evaluated the percutaneous tracts injected with the fibrin sealant (FS) Evicel and hemostatic gelatin matrix (HG ... Full text Link to item Cite

The digital flexible ureteroscope: In vitro assessment of optical characteristics

Journal article International Braz J Urol · May 1, 2011 Introduction: Recent advances in endoscope design have placed the charged coupled device chip on the tip of the endoscope. The image is instantly digitalized and converted into an electrical signal for transmission. Digital technology was first introduced ... Full text Cite

The digital flexible ureteroscope: in vitro assessment of optical characteristics.

Journal article J Endourol · March 2011 INTRODUCTION: Recent advances in endoscope design have placed the charged coupled device chip on the tip of the endoscope. The image is instantly digitalized and converted into an electrical signal for transmission. Digital technology was first introduced ... Full text Link to item Cite

A simple method for fabricating artificial kidney stones of different physical properties.

Journal article Urol Res · August 2010 A simple method for preparing artificial kidney stones with varying physical properties is described. BegoStone was prepared with a powder-to-water ratio ranging from 15:3 to 15:6. The acoustic properties of the phantoms were characterized using an ultraso ... Full text Link to item Cite

Effect of lithotripter focal width on stone comminution in shock wave lithotripsy.

Journal article J Acoust Soc Am · April 2010 Using a reflector insert, the original HM-3 lithotripter field at 20 kV was altered significantly with the peak positive pressure (p(+)) in the focal plane increased from 49 to 87 MPa while the -6 dB focal width decreased concomitantly from 11 to 4 mm. Usi ... Full text Open Access Link to item Cite

Dual-energy computed tomography with advanced postimage acquisition data processing: improved determination of urinary stone composition.

Journal article J Endourol · March 2010 INTRODUCTION: The characterization of urinary calculi using noninvasive methods has the potential to affect clinical management. CT remains the gold standard for diagnosis of urinary calculi, but has not reliably differentiated varying stone compositions. ... Full text Open Access Link to item Cite

A composite kidney stone phantom with mechanical properties controllable over the range of human kidney stones.

Journal article J Mech Behav Biomed Mater · January 2010 A novel composite kidney stone phantom has been developed. This stone phantom is producible with mechanical properties mimicking the range of tensile fracture strength and acoustic properties of human kidney stones and is an inorganic/organic composite mat ... Full text Link to item Cite

A hands-on approach to computational methods in engineering

Journal article ASEE Annual Conference and Exposition, Conference Proceedings · September 1, 2009 The Pratt School of Engineering at Duke University has been actively focusing on the development of a variety of mechanisms to provide undergraduate engineering students with an earlier, more practical, experience with engineering concepts. Through these m ... Cite

Effect of beam size on stone comminution in shock wave lithotripsy

Journal article Aip Conference Proceedings · July 21, 2009 The effect of beam size on stone comminution in the Dornier HM-3 lithotripter were investigated using a modified reflector (MR), which was developed to produce an acoustic field with higher peak pressure and smaller beam size compared to the original refle ... Full text Cite

Renal stone assessment with dual-energy multidetector CT and advanced postprocessing techniques: improved characterization of renal stone composition--pilot study.

Journal article Radiology · March 2009 PURPOSE: To prospectively evaluate the capability of noninvasive, simultaneous dual-energy (DE) multidetector computed tomography (CT) to improve characterization of human renal calculi in an anthropomorphic DE renal phantom by introducing advanced postpro ... Full text Link to item Cite

High definition laparoscopy: objective assessment of performance characteristics and comparison with standard laparoscopy.

Journal article J Endourol · March 2009 INTRODUCTION: High definition (HD) digital imaging represents a major advance in endoscope technology. The development of the charge-coupled device chip and its location at the distal end of the endoscope allows for image capture and digitization, as well ... Full text Link to item Cite

The effect of frequency doubled double pulse Nd:YAG laser fiber proximity to the target stone on transient cavitation and acoustic emission.

Journal article J Urol · April 2007 PURPOSE: Scant information has been published describing the effect of laser fiber distance from the stone target on the mechanism of calculus fragmentation. Using high speed photography and acoustic emission measurements we characterized the impact of las ... Full text Link to item Cite

Effects of tandem pulse on stone comminution in an electromagnetic shock wave lithotripter

Journal article ASME International Mechanical Engineering Congress and Exposition Proceedings Imece · January 1, 2007 Despite recent innovations in lithotripter design and technology, the first generation Dornier HM-3 electrohydraulic lithotripter remains the most effective clinical, non-invasive modality for comminuting stones. Understanding the fundamental differences b ... Full text Cite

Comparison of stone comminution produced by two different reflector configurations in an HM-3 lithotripter

Journal article ASME International Mechanical Engineering Congress and Exposition Proceedings Imece · January 1, 2007 Clinical experience has demonstrated that the performance of the 2nd and 3rd generation shock wave lithotripters in terms of stone comminution has become inferior to the 1st generation Dornier HM-3 lithotripter. A primary change in th ... Full text Cite

Shock wave interaction with laser-generated single bubbles.

Journal article Physical review letters · July 2005 The interaction of a lithotripter shock wave (LSW) with laser-generated single vapor bubbles in water is investigated using high-speed photography and pressure measurement via a fiber-optic probe hydrophone. The interaction leads to nonspherical collapse o ... Full text Cite

Hypervelocity launching and frozen fuels as a major contribution to spaceflight

Journal article JBIS Journal British Interplanetary Society · January 1, 2005 Acting as a virtual first stage, a hypervelocity launch together with the use of frozen hydrogen/frozen oxygen propellant, offers a Single-Stage-To-Orbit (SSTO) system that promises an enormous increase in SSTO massratio. Ram acceleration provides hypervel ... Cite

Lunar ice: Adsorbed water on subsurface polar dust

Journal article Icarus · January 1, 2002 Differential scanning calorimetry indicates that adsorbed water and goethite, a product of hydrated ilmenite, are thermally stable over geologic time in the lunar polar regions. Adsorbed water can undergo burial as a result of several mechanisms, thereby a ... Full text Cite

On the response of a shaken cable-suspended mass

Journal article Proceedings of the ASME Design Engineering Technical Conference · January 1, 2001 A small mass is suspended by two cables which are attached at angles to a rigid frame. The frame is shaken harmonically in the horizontal direction, causing the mass to respond typically in an erratic manner as the cables alternately become taut and slack. ... Cite