Laurens E. Howle

Journal Article High Alt Med Biol · October 8, 2024 There is interest among technical, expedition, commercial, and military divers in expanding diving operations to high altitude. However, altitude diving presents unique challenges including acclimatization, increased decompression sickness (DCS) risk, and ... Full text Link to item Cite

Computational fluid dynamics of flow regime and hydrodynamic forces generated by a gliding North Atlantic right whale (Eubalaena glacialis)

Journal Article Marine Mammal Science · July 1, 2021 Accurate estimates of drag on marine animals are required to investigate the locomotive cost, propulsive efficiency, and the impacts of entanglement if the animal is carrying fishing gear. In this study, we performed computational fluid dynamics analysis o ... Full text Cite

Hemodialysis catheter integrity during mechanical power injection of iodinated contrast medium for computed tomography angiography.

Journal Article Abdom Radiol (NY) · June 2021 PURPOSE: CT angiography (CTA) requires vascular access with flow rates of 5-7 mL/s. Hemodialysis (HD) is performed at 6-10 mL/s. The purpose of our study is to evaluate the structural integrity of HD catheters in the administration of contrast media via a ... Full text Link to item Cite

Trinomial decompression sickness model using full, marginal, and non-event outcomes.

Journal Article Computers in biology and medicine · March 2020 Decompression sickness (DCS) is a condition associated with reductions in ambient pressure during underwater diving and altitude exposure. Determining the risk of DCS from a dive exposure remains an active area of research, with the goal of developing safe ... Full text Cite

A study of decompression sickness using recorded depth-time profiles.

Journal Article Undersea Hyperb Med · 2020 INTRODUCTION: 122,129 dives by 10,358 recreational divers were recorded by dive computers from 11 manufacturers in an exploratory study of how dive profile, breathing gas (air or nitrox [N2/O2] mixes), repetitive diving, gender, age, and dive site conditio ... Full text Link to item Cite

Tetranomial decompression sickness model using serious, mild, marginal, and non-event outcomes

Journal Article Informatics in Medicine Unlocked · January 1, 2020 Decompression sickness (DCS) is a condition resulting from reductions in ambient pressure, causing inert gas bubbles in tissues. This work focuses on hyperbaric exposures, specifically DCS resulting from underwater diving. Signs and symptoms of DCS can ran ... Full text Cite

Are interconnected compartmental models more effective at predicting decompression sickness risk?

Journal Article Informatics in Medicine Unlocked · January 1, 2020 Interconnected tissue compartmental models having two, three, or four compartments, one or more of which was risk-bearing, have been previously investigated for predicting the probability of decompression sickness (DCS) in compressed gas diving. We extend ... Full text Cite

Simulation of the entanglement of a North Atlantic right whale (Eubalaena glacialis) with fixed fishing gear

Journal Article Marine Mammal Science · July 1, 2019 Population estimates of the critically endangered North Atlantic right whale (Eubalaena glacialis) put the number of individuals at 458 with the actual number likely being lower due to a recent unusual mortality event. Entanglement with fixed fishing gear ... Full text Cite

Probabilistic pharmacokinetic models of decompression sickness in humans: Part 2, coupled perfusion-diffusion models.

Journal Article Computers in biology and medicine · January 2018 Decompression sickness (DCS) can be experienced following a reduction in ambient pressure; such as that associated with diving or ascent to high altitudes. DCS is believed to result when supersaturated inert gas dissolved in biological tissues exits soluti ... Full text Cite

Iso-risk air no decompression limits after scoring marginal decompression sickness cases as non-events.

Journal Article Computers in biology and medicine · January 2018 Decompression sickness (DCS) in humans is associated with reductions in ambient pressure that occur during diving, aviation, or certain manned spaceflight operations. Its signs and symptoms can include, but are not limited to, joint pain, radiating abdomin ... Full text Cite

Bimodal decompression sickness onset times are not related to dive type or event severity.

Journal Article Computers in biology and medicine · December 2017 Human decompression sickness (DCS) is a condition associated with depressurization during underwater diving. Human research dive trial data containing dive outcome (DCS, no-DCS) and symptom information are used to calibrate probabilistic DCS models. DCS sy ... Full text Cite

Probabilistic pharmacokinetic models of decompression sickness in humans, part 1: Coupled perfusion-limited compartments.

Journal Article Computers in biology and medicine · July 2017 Decompression sickness (DCS) is a disease caused by gas bubbles forming in body tissues following a reduction in ambient pressure, such as occurs in scuba diving. Probabilistic models for quantifying the risk of DCS are typically composed of a collection o ... Full text Cite

Bayesian approach to decompression sickness model parameter estimation.

Journal Article Computers in biology and medicine · March 2017 We examine both maximum likelihood and Bayesian approaches for estimating probabilistic decompression sickness model parameters. Maximum likelihood estimation treats parameters as fixed values and determines the best estimate through repeated trials, where ... Full text Cite

From the track to the ocean: Using flow control to improve marine bio-logging tags for cetaceans.

Journal Article PloS one · January 2017 Bio-logging tags are an important tool for the study of cetaceans, but superficial tags inevitably increase hydrodynamic loading. Substantial forces can be generated by tags on fast-swimming animals, potentially affecting behavior and energetics or promoti ... Full text Cite

The probability and severity of decompression sickness.

Journal Article PLoS One · 2017 Decompression sickness (DCS), which is caused by inert gas bubbles in tissues, is an injury of concern for scuba divers, compressed air workers, astronauts, and aviators. Case reports for 3322 air and N2-O2 dives, resulting in 190 DCS events, were retrospe ... Full text Link to item Cite

Hydrodynamic performance of the flippers of large-bodied cetaceans in relation to locomotor ecology

Journal Article Marine Mammal Science · January 1, 2014 Cetaceans evolved flippers that are unique in both size and shape probably due to selection pressures associated with foraging and body size. Flippers function as control surfaces for maneuverability and stability. Flippers of cetaceans and engineered hydr ... Full text Cite

Advances in cetacean telemetry: A review of single-pin transmitter attachment techniques on small cetaceans and development of a new satellite-linked transmitter design

Journal Article Marine Mammal Science · January 1, 2014 Electronic tags have proven to be valuable tools in assessing small cetacean movement and behavior. However, problems associated with tag size and attachment have limited duration and damaged dorsal fins. These outcomes have motivated researchers to develo ... Full text Cite

Drag of suction cup tags on swimming animals: Modeling and measurement

Journal Article Marine Mammal Science · January 1, 2014 Bio-logging tags are widely used to study the behavior and movements of marine mammals with the tacit assumption of little impact to the animal. However, tags on fast-swimming animals generate substantial hydrodynamic forces potentially affecting behavior ... Full text Cite

Analytic gain in probabilistic decompression sickness models.

Journal Article Computers in biology and medicine · November 2013 Decompression sickness (DCS) is a disease known to be related to inert gas bubble formation originating from gases dissolved in body tissues. Probabilistic DCS models, which employ survival and hazard functions, are optimized by fitting model parameters to ... Full text Cite

Drag of suction cup tags on swimming animals: Modeling and measurement

Journal Article Marine Mammal Science · 2013 Cite

Hydrodynamic performance of the flippers of large-bodied cetaceans in relation to locomotor ecology

Journal Article Marine Mammal Science · 2013 Cite

Advances in cetacean telemetry: A review of single-pin transmitter attachment techniques on small cetaceans and development of a new satellite-linked transmitter design

Journal Article Marine Mammal Science · 2013 Cite

Improved aortic enhancement in CT angiography using slope-based triggering with table speed optimization: a pilot study.

Journal Article Int J Cardiovasc Imaging · August 2012 To assess whether a scan triggering technique based on the slope of the time-attenuation curve combined with table speed optimization may improve arterial enhancement in aortic CT angiography compared to conventional threshold-based triggering techniques. ... Full text Link to item Cite

Contrast-enhanced magnetic resonance angiography: first-pass arterial enhancement as a function of gadolinium-chelate concentration, and the saline chaser volume and injection rate.

Journal Article Invest Radiol · February 2012 OBJECTIVE: To evaluate the effect of the contrast medium (CM) concentration and the saline chaser volume and injection rate on first-pass aortic enhancement characteristics in contrast-enhanced magnetic resonance angiography using a physiologic flow phanto ... Full text Link to item Cite

The tubercles on humpback whales' flippers: application of bio-inspired technology.

Journal Article Integrative and comparative biology · July 2011 The humpback whale (Megaptera novaeangliae) is exceptional among the large baleen whales in its ability to undertake aquabatic maneuvers to catch prey. Humpback whales utilize extremely mobile, wing-like flippers for banking and turning. Large rounded tube ... Full text Cite

Marine applications of the biomimetic humpback whale flipper

Journal Article Marine Technology Society Journal · July 1, 2011 The biomimetic approach seeks technological advancement through a transfer of technology from natural technologies to engineered systems. The morphology of the wing-like flipper of the humpback whale has potential for marine applications. As opposed to the ... Full text Cite

A simplified mass-transfer model for visual pigments in amphibian retinal-cone outer segments.

Journal Article Biophys J · February 2, 2011 When radiolabeled precursors and autoradiography are used to investigate turnover of protein components in photoreceptive cone outer segments (COSs), the labeled components--primarily visual pigment molecules (opsins)--are diffusely distributed along the C ... Full text Link to item Cite

Computational evaluation of the performance of lifting surfaces with leading-edge protuberances

Journal Article Journal of Aircraft · January 1, 2011 The leading-edge tubercles of humpback whale flippers have been shown to enhance hydrodynamic performance by increasing lift and decreasing drag poststall. To explore this effect, computational simulations of two models based on an idealized humpback whale ... Full text Cite

Hydrodynamic performance of the flippers of large-bodied cetaceans

Journal Article Secondary Adaptation of Tetrapods to Life in Water · 2011 Cite

Response

Journal Article Radiology · May 1, 2010 Full text Cite

Lift, drag, and cavitation onset on rudders with leading-edge tubercles

Journal Article Marine Technology · January 1, 2010 This paper presents the experimental measurement of lift and drag as well as the determination of the onset of cavitation on rudders with leading-edge protuberances (tubercles) that are operating at low to moderate Reynolds Numbers in water. The leading-ed ... Cite

Central venous catheter integrity during mechanical power injection of iodinated contrast medium.

Journal Article Radiology · December 2009 PURPOSE: To evaluate a widely used nontunneled triple-lumen central venous catheter in order to determine whether the largest of the three lumina (16 gauge) can tolerate high flow rates, such as those required for computed tomographic angiography. MATERIAL ... Full text Link to item Cite

A computationally advantageous system for fitting probabilistic decompression models to empirical data.

Journal Article Computers in biology and medicine · December 2009 To investigate the nature and mechanisms of decompression sickness (DCS), we developed a system for evaluating the success of decompression models in predicting DCS probability from empirical data. Model parameters were estimated using maximum likelihood t ... Full text Cite

Comparison of real and idealized cetacean flippers.

Journal Article Bioinspiration & biomimetics · December 2009 When a phenomenon in nature is mimicked for practical applications, it is often done so in an idealized fashion, such as representing the shape found in nature with convenient, piece-wise smooth mathematical functions. The aim of idealization is to capture ... Full text Cite

Contrast material administration protocols for 64-MDCT angiography: altering volume and rate and use of a saline chaser to better match the imaging window--physiologic phantom study.

Journal Article AJR Am J Roentgenol · December 2009 OBJECTIVE: The purpose of our study was to evaluate the effect of varying volumes and rates of contrast material, use of a saline chaser, and cardiac output on aortic enhancement characteristics in MDCT angiography (MDCTA) using a physiologic phantom. MATE ... Full text Link to item Cite

Marginal DCS events: their relation to decompression and use in DCS models.

Journal Article Journal of applied physiology (Bethesda, Md. : 1985) · November 2009 We consider the nature and utility of marginal decompression sickness (DCS) events in fitting probabilistic decompression models to experimental dive trial data. Previous works have assigned various fractional weights to marginal DCS events, so that they c ... Full text Cite

Modifying peripheral IV catheters with side holes and side slits results in favorable changes in fluid dynamic properties during the injection of iodinated contrast material.

Journal Article AJR Am J Roentgenol · October 2009 OBJECTIVE: The purpose of this study was to compare a standard peripheral end-hole angiocatheter with those modified with side holes or side slits using experimental optical techniques to qualitatively compare the contrast material exit jets and using nume ... Full text Link to item Cite

Lift and drag performance of odontocete cetacean flippers.

Journal Article The Journal of experimental biology · July 2009 Cetaceans (whales, dolphins and porpoises) have evolved flippers that aid in effective locomotion through their aquatic environments. Differing evolutionary pressures upon cetaceans, including hunting and feeding requirements, and other factors such as ani ... Full text Cite

Resolution and severity in decompression illness.

Journal Article Aviat Space Environ Med · May 2009 omegaWe review the terminology of decompression illness (DCI), investigations of residual symptoms of decompression sickness (DCS), and application of survival analysis for investigating DCI severity and resolution. The Type 1 and Type 2 DCS classification ... Full text Link to item Cite

Ecological morphology of the flippers of cetaceans based on two-dimensional geometry

Journal Article INTEGRATIVE AND COMPARATIVE BIOLOGY · February 1, 2009 Link to item Cite

Hydrodynamic flow control in marine mammals.

Journal Article Integrative and comparative biology · December 2008 The ability to control the flow of water around the body dictates the performance of marine mammals in the aquatic environment. Morphological specializations of marine mammals afford mechanisms for passive flow control. Aside from the design of the body, w ... Full text Cite

Effect of varying injection rates of a saline chaser on aortic enhancement in CT angiography: phantom study.

Journal Article Eur Radiol · August 2008 The effect of varying injection rates of a saline chaser on aortic enhancement in computed tomography (CT) angiography was determined. Single-level, dynamic CT images of a physiological flow phantom were acquired between 0 and 50 s after initiation of cont ... Full text Link to item Cite

Experimental evaluation of sinusoidal leading edges

Journal Article Journal of Aircraft · January 1, 2007 Experimental evaluation of the sinusoidal leading-edge (LE) planforms on an NACA 63-021 airfoil section are discussed. The larger amplitude sinusoids created 'softer' stall characteristics by maintaining attached flow at the peaks despite separated flow in ... Full text Cite

Leading-edge tubercles delay stall on humpback whale (Megaptera novaeangliae) flippers

Journal Article Physics of Fluids · January 1, 2004 The humpback whale (Megaptera novaeangliae) is exceptional among the baleen whales in its ability to undertake acrobatic underwater maneuvers to catch prey. In order to execute these banking and turning maneuvers, humpback whales utilize extremely mobile f ... Full text Cite

Delayed stall due to leading edge tubercles of the humpback whale flipper

Journal Article INTEGRATIVE AND COMPARATIVE BIOLOGY · December 1, 2003 Link to item Cite

Positive feedback control of Rayleigh-Bénard convection

Journal Article Discrete and Continuous Dynamical Systems - Series B · November 1, 2003 We consider the problem of active feedback control of Rayleigh-Bénard convection via shadowgraphic measurement. Our theoretical studies show, that when the feedback control is positive, i.e. is tuned to advance the onset of convection, there is a critical ... Cite

Spring stiffness influence on an oscillating propulsor

Journal Article Journal of Fluids and Structures · January 1, 2003 We study the propulsive dynamics of a thin foil pitching about its quarter chord and allowed to passively plunge. Specifically, we focus on the effect of variations in translational spring stiffness on propulsor plunge and on the minimum oscillation freque ... Full text Cite

Evaluation of synthetic phospholipid ultrasound contrast agents.

Journal Article Ultrasonics · November 2002 The echogenic properties of synthetic, phospholipid encapsulated, air-filled microbubbles with various carbon-chain length as ultrasound contrast agents are investigated through the use of a flow-through laboratory ultrasound system. Specifically, we inves ... Full text Cite

The effect of boundary properties on controlled Rayleigh-Benard convection

Journal Article Journal of Fluid Mechanics · May 25, 2000 We investigate the effect of the finite horizontal boundary properties on the critical Rayleigh and wave numbers for controlled Rayleigh-Benard convection in an infinite horizontal domain. Specifically, we examine boundary thickness, thermal diffusivity an ... Full text Cite

Bifurcation control of Rayleigh-Benard convection

Journal Article IEEE Conference on Control Applications - Proceedings · December 1, 1999 Bifurcation control deals with the modification of the bifurcation characteristics of a parameterized nonlinear system by a judiciously designed control input. In this paper, we investigate the problem of active control of Rayleigh-Benard convection (RBC) ... Cite

Effects of anisotropy and boundary plates on the critical values of a porous medium heated from below

Journal Article International Journal of Heat and Mass Transfer · September 1, 1999 We present a linear stability analysis of Horton-Rogers-Lapwood convection in an anisotropic porous medium bounded by finite-property plates of infinite horizontal extent. Critical values for the onset of convection are obtained using a continuation method ... Full text Cite

Experimental evaluation of the thermal properties of two tissue equivalent phantom materials.

Journal Article Int J Hyperthermia · 1999 Tissue equivalent radio frequency (RF) phantoms provide a means for measuring the power deposition of various hyperthermia therapy applicators. Temperature measurements made in phantoms are used to verify the accuracy of various numerical approaches for co ... Full text Link to item Cite

Amplitude control of bifurcations and application to Rayleigh-Benard convection

Journal Article Proceedings of the IEEE Conference on Decision and Control · December 1, 1998 Bifurcation control deals with the modification of the bifurcation characteristics of a parameterized nonlinear system by a judiciously designed control input. In this paper, we focus on the problem of controlling the amplitude of bifurcated solutions. It ... Cite

Lithotripsy: The treatment of kidney stones with shock waves

Journal Article SIAM Review · January 1, 1998 This paper discusses mathematical models for the response of a small air bubble in water to an ultrasound pulse, a context that arises in the modern treatment for kidney stones. The paper reviews Rayleigh's 1917 theory for bubble response, applies asymptot ... Full text Cite

Convection and flow in porous media. Part 2. Visualization by shadowgraph

Journal Article Journal of Fluid Mechanics · February 10, 1997 We present results for pattern formation at the onset of convection in fluid-saturated porous media obtained by a novel variation on the shadowgraphic technique (modified shadowgraphic technique). Both ordered and disordered media are used, each exhibiting ... Full text Cite

Control of Rayleigh-Bénard convection in a small aspect ratio container

Journal Article International Journal of Heat and Mass Transfer · January 1, 1997 Active control of Rayleigh-Bénard convection in small aspect ratio horizontal layer, by perturbation of the lower thermal boundary condition, is shown. These experiments use a novel shadowgraphic system to measure the departure of a high Prandtl number flu ... Full text Cite

Active control of Rayleigh-Bénard convection

Journal Article Physics of Fluids · January 1, 1997 We report on stabilizing the unstable no-motion state in a moderate aspect ratio one-dimensional Rayleigh-Bénard convection experiment. A linear proportional control algorithm uses shadowgraphic convection images to determine heat flux perturbations which ... Full text Cite

Response to a lithotripter shock wave of a cavitation bubble surrounded by a viscoelastic membrane

Journal Article American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED · January 1, 1997 A model is proposed for the dynamics of an in vivo cavitation bubble. The model includes the effects of a viscoelastic membrane. It can accurately describe bubble dynamics when subjected to a focused shock wave source. ... Cite

Linear stability analysis of controlled Rayleigh-Bénard convection using shadowgraphic measurement

Journal Article Physics of Fluids · January 1, 1997 We conduct a linear stability analysis of Rayleigh-Bénard convection in an infinite horizontal layer with active control of the lower boundary heat flux. A simple linear proportional control loop uses a shadowgraph of the convection pattern to actively dis ... Full text Cite

A comparison of the reduced Galerkin and pseudo-spectral methods for simulation of steady Rayleigh-Bénard convection

Journal Article International Journal of Heat and Mass Transfer · January 1, 1996 A study of the computational efficiency of two numerical methods based on a mixed finite difference-Galerkin technique is undertaken. This study uses steady Rayleigh-Bénard convection in a periodic container as a model problem. The formulation and lineariz ... Full text Cite

Control of Rayleigh-Benard convection in small aspect ratio containers

Journal Article American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED · December 1, 1995 If the temperature gradient across a horizontal fluid layer is great enough, Rayleigh-Benard convection (RBC) is initiated and thermal transport is increased. Eliminating RBC at higher than critical temperature gradient would allow these gradients to be ma ... Cite

Natural convection in porous media with anisotropic dispersive thermal conductivity

Journal Article International Journal of Heat and Mass Transfer · January 1, 1994 A numerical simulation is undertaken in order to study the effect of anisotropy of the effective thermal conductivity tensor on heat transport in the porous medium Rayleigh-Bénard problem. The momentum equation includes an inertial drag (Forchheimer) term. ... Full text Cite

Efficient implementation of a finite-difference/galerkin method for simulation of large aspect ratio convection

Journal Article Numerical Heat Transfer, Part B: Fundamentals · January 1, 1994 The efficiency of a mixed finite-difference / Galerkin method is examined for simulation of steady two-dimensional Rayleigh-Bénard convection of large aspect ratio. It is found that computation time is reduced by an order of magnitude for large-aspect-rati ... Full text Cite

Visualization of natural convection in ordered and disordered porous layers

Journal Article American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED · December 1, 1993 The recent Modified Shadowgraphic Technique is used to study pattern formation of convecting flows in fluid saturated porous layers. Both regular and random media are explored, each exhibiting distinct primary bifurcation behavior. In regular porous layers ... Cite

Visualization of convective fluid flow in a porous medium

Journal Article Nature · January 1, 1993 WHEN a horizontal layer of fluid is heated from below, it may undergo Rayleigh-Benard convection (RBC), leading to the spontaneous appearance of regular patterns of fluid flow1. The shadow-graph technique 2, which allows visualization of the convection pat ... Full text Cite

Visualization of convective fluid flow in a porous medium

Journal Article Nature · 1993 WHEN a horizontal layer of fluid is heated from below, it may undergo Rayleigh-Benard convection (RBC), leading to the spontaneous appearance of regular patterns of fluid flow. The shadow-graph technique, which allows visualization of the convection patter ... Cite