scholarly journals Introducing SiTTE: A controlled laboratory setting to study the impact of turbulent fluctuations on light propagation in the underwater environment

2017 ◽  
Vol 25 (5) ◽  
pp. 5662 ◽  
Author(s):  
Silvia Matt ◽  
Weilin Hou ◽  
Wesley Goode ◽  
Sam Hellman
Keyword(s):  
Light Propagation ◽  
Laboratory Setting ◽  
Turbulent Fluctuations ◽  
Underwater Environment ◽  
The Impact

scholarly journals Towards Transabdominal Functional Photoacoustic Imaging of the Placenta: Improvement in Imaging Depth Through Optimization of Light Delivery

2021 ◽  
Author(s):  
Kristie Huda ◽  
Kenneth F. Swan ◽  
Cecilia T. Gambala ◽  
Gabriella C. Pridjian ◽  
Carolyn L. Bayer
Keyword(s):  
Delivery System ◽  
Light Propagation ◽  
Ex Vivo ◽  
Photoacoustic Imaging ◽  
Incidence Angle ◽  
Incident Angle ◽  
Placental Tissue ◽  
Light Delivery ◽  
Imaging Depth ◽  
The Impact

AbstractFunctional photoacoustic imaging of the placenta could provide an innovative tool to diagnose preeclampsia, monitor fetal growth restriction, and determine the developmental impacts of gestational diabetes. However, transabdominal photoacoustic imaging is limited in imaging depth due to the tissue’s scattering and absorption of light. The aim of this paper was to investigate the impact of geometry and wavelength on transabdominal light delivery. Our methods included the development of a multilayer model of the abdominal tissue and simulation of the light propagation using Monte Carlo methods. A bifurcated light source with varying incident angle of light, distance between light beams, and beam area was simulated to analyze the effect of light delivery geometry on the fluence distribution at depth. The impact of wavelength and the effects of variable thicknesses of adipose tissue and muscle were also studied. Our results showed that the beam area plays a major role in improving the delivery of light to deep tissue, in comparison to light incidence angle or distance between the bifurcated fibers. Longer wavelengths, with incident fluence at the maximum permissible exposure limit, also increases fluence within deeper tissue. We validated our simulations using a commercially available light delivery system and ex vivo human placental tissue. Additionally, we compared our optimized light delivery to a commercially available light delivery system, and conclude that our optimized geometry could improve imaging depth more than 1.6×, bringing the imaging depth to within the needed range for transabdominal imaging of the human placenta.

End-user Preference for and Understanding of Hurricane Forecast Graphs

2021 ◽  
Vol 65 (1) ◽  
pp. 606-610
Author(s):  
Barbara Millet ◽  
Sharanya J. Majumdar ◽  
Alberto Cairo ◽  
Carolina Diaz ◽  
Qinyu Ding ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Risk Communication ◽  
Prior Experience ◽  
User Preference ◽  
Laboratory Setting ◽  
End User ◽  
Temporal Uncertainty ◽  
Spatio Temporal ◽  
The Impact ◽  
National Hurricane Center

Hurricane forecast graphics have the challenging task of communicating information about spatio-temporal uncertainty. This study assesses the impact of graph literacy and graph format on user preference and understanding. In a laboratory setting, we compared user responses to official National Hurricane Center advisory maps and alternative visualizations. Results indicate that prior experience with a visualization drives preference and that graph literacy, visualization format, and tropical cyclone characteristics, in combination, influence interpretations of hurricane forecast track. The findings from this study are expected to inform redesign efforts of hurricane risk communication products.

Air Travel and Contact Lenses: A Laboratory Study

1988 ◽  
Vol 32 (6) ◽  
pp. 450-454
Author(s):  
Joseph E. Laviana ◽  
Frederick H. Rohles
Keyword(s):  
Relative Humidity ◽  
Contact Lenses ◽  
Flight Time ◽  
Air Travel ◽  
The Other ◽  
Laboratory Setting ◽  
Soft Contact ◽  
Soft Contact Lenses ◽  
Significant Difference ◽  
The Impact

The cabin of an inflight aircraft contains approximately 10% relative humidity (rh). To investigate the impact of this environment on eye comfort, an inflight humidity profile was simulated in a controlled laboratory setting. The experiment was replicated 3 times using a group of 4 subjects (2 males; 2 females) per test. Participants served in both control and experimental roles by wearing a hydrophilic contact lens on one eye and no lens on the other. Subjects provided evaluations of “eye comfort” for both eyes (contact and naked) at specified intervals during the 10 hour test. The results indicated that at 10% rh, there was no significant difference in eye comfort for either wearers or nonwearers of soft contact lenses. However, comfort decreased with the length of exposure (flight time), and for durations of six hours or longer a significant annoyance was reported.

Microthermography of diode lasers: The impact of light propagation on image formation

2009 ◽  
Vol 105 (1) ◽  
pp. 014502 ◽  
Author(s):  
Julien LeClech ◽  
Mathias Ziegler ◽  
Jayanta Mukherjee ◽  
Jens W. Tomm ◽  
Thomas Elsaesser ◽  
...  
Keyword(s):  
Light Propagation ◽  
Diode Lasers ◽  
Image Formation ◽  
The Impact

Spatial density and ambient scent: effects on consumer anxiety

2014 ◽  
Vol 29 (1) ◽  
pp. 76-94 ◽  
Author(s):  
Tina Poon ◽  
Bianca Grohmann
Keyword(s):  
Spatial Perception ◽  
Experimental Manipulation ◽  
Spatial Density ◽  
Laboratory Setting ◽  
Content Type ◽  
Anxiety Levels ◽  
Enclosed Space ◽  
Retail Setting ◽  
Ambient Scent ◽  
The Impact

Purpose – This replication and extension of Hirsch and Gruss examines the impact of spatial density and ambient scent on consumers' spatial perception and anxiety. The paper aims to discuss these issues. Design/methodology/approach – A 2 (spatial density: high, low)×3 (ambient scent: no scent, scent associated with spaciousness, scent associated with enclosed spaces) between-participants experimental design was implemented in a laboratory setting. A pretest determined scent selection and manipulation checks were successful. Findings – Spatial perception was influenced by spatial density, but not ambient scent. Ambient scent and spatial density interacted, such that consumers' anxiety levels significantly increased under conditions of low spatial density combined with an ambient scent associated with spaciousness, and directionally increased under conditions of high spatial density combined with ambient scent associated with enclosed space. Research limitations/implications – This research was conducted in a laboratory setting in order to increase experimental control. An exploration of the strength of the observed effects in a field (retail) setting would be insightful. Practical implications – Results of this study suggest that retailers need to consider both spatial density and choice of ambient scent carefully in order to reduce consumers' anxiety levels. Originality/value – This research is one of the few to consider the impact of spatial density and ambient scent on consumers' anxiety levels. The use of a between-participants design and the experimental manipulation of both spatial density and ambient scent results in a more rigorous test of the scent – anxiety relation observed in previous research.

Role of Turbulence in Precessing Vortex Core Dynamics

2019 ◽  
Author(s):  
Ashwini Karmarkar ◽  
Mark Frederick ◽  
Sean Clees ◽  
Danielle Mason ◽  
Jacqueline O’Connor
Keyword(s):  
Large Scale ◽  
Swirling Flows ◽  
Base Flow ◽  
Van Der Pol Oscillator ◽  
Intensity Increase ◽  
Swirl Number ◽  
Time Resolved ◽  
Turbulent Fluctuations ◽  
Eddy Viscosity Model ◽  
The Impact

Abstract Precessing vortex cores (PVC), arising from a global instability in swirling flows, can dramatically alter the dynamics of swirl-stabilized flames. Previous study of these instabilities has identified their frequencies and potential for interaction with the shear layer instabilities also present in swirling flows. In this work, we investigate the dynamics of precessing vortex cores at a range of swirl numbers and the impact that turbulence, which tends to increase with swirl number due to the increase in mean shear, has on the dynamics of this instability. This is particularly interesting as stability predictions have previously incorporated turbulence effects using an eddy viscosity model, which only captures the impact of turbulence on the base flow, not on the instantaneous dynamics of the PVC itself. Time-resolved experimental measurements of the three-component velocity field at ten swirl numbers show that at lower swirl numbers, the PVC is affected by turbulence through the presence of vortex jitter. With increasing swirl number, the PVC jitter decreases as the PVC strength increases. There is a critical swirl number below which jitter of the PVC vortex monotonically increases with increasing swirl number, and beyond which the jitter decreases, indicating that the strength of the PVC dominates over turbulent fluctuations at higher swirl numbers, despite the fact that the turbulence intensities continue to rise with increasing swirl number. Further, we use a nonlinear van der Pol oscillator model to explain the competition between the random turbulent fluctuations and coherent oscillations of the PVC. The results of this work indicate that while both the strength of the PVC and magnitude of turbulence intensity increase with increasing swirl number, there are defined regimes where each of them hold a stronger influence on the large-scale, coherent dynamics of the flow field.

Effects of turbulent fluctuations on phase partitioning in adiabatic mixed-phase cloud parcels

2021 ◽  
Author(s):  
Daniel Gomes Albuquerque ◽  
Gustavo Coelho Abade ◽  
Hanna Pawłowska
Keyword(s):  
Turbulent Mixing ◽  
Scalar Fields ◽  
Mixed Phase ◽  
Liquid Droplets ◽  
Growth Environment ◽  
Phase Partitioning ◽  
Turbulent Fluctuations ◽  
Locally Homogeneous ◽  
The Impact ◽  
Local Variability

<p>Several microphysical processes determine phase partitioning between ice and liquid water in a mixed-phase cloud. Here we investigate the collective growth of ice particles and liquid droplets affected by turbulent fluctuations in temperature and water vapor fields. All cloud particles, including inactivated nuclei (both CCN and IN), are described by Lagrangian super-particles. To account for local variability in the turbulent cloud environment we apply a Lagrangian microphysical scheme, where temperature and vapor mixing ratio are stochastic attributes attached to each super-particle. In addition, a simple linear relaxation scheme models turbulent mixing of the scalar fields probed by each super-particle. The limit of a locally homogeneous growth environment corresponds to an infinitely short turbulent mixing timescale. The impact of our Lagrangian microphysical scheme on phase partitioning is tested in adiabatic cloud parcel simulations. Results are confronted with idealized reference simulations that use bulk microphysics based on an assumed (temperature-dependent) phase partitioning function. Our study suggests that accounting for local variability in a turbulent cloud is important for reproducing steady-state mixed-phase conditions.</p>

scholarly journals Past and Present Trends in the Development of the Pattern-Formation Theory: Domain Walls and Quasicrystals

Physics ◽  
2021 ◽  
Vol 3 (4) ◽  
pp. 1015-1045
Author(s):  
Boris A. Malomed
Keyword(s):  
Pattern Formation ◽  
Light Propagation ◽  
Domain Walls ◽  
Three Dimensional ◽  
Present Review ◽  
Ginzburg Landau ◽  
Coupled Equations ◽  
Derivative Term ◽  
Bose Einstein ◽  
The Impact

A condensed review is presented for two basic topics in the theory of pattern formation in nonlinear dissipative media: (i) domain walls (DWs, alias grain boundaries), which appear as transient layers between different states occupying semi-infinite regions, and (ii) two- and three-dimensional (2D and 3D) quasiperiodic (QP) patterns, which are built as a superposition of plane–wave modes with incommensurate spatial periodicities. These topics are selected for the present review, dedicated to the 70th birthday of Professor Michael I. Tribelsky, due to the impact made on them by papers of Prof. Tribelsky and his coauthors. Although some findings revealed in those works may now seem “old”, they keep their significance as fundamentally important results in the theory of nonlinear DW and QP patterns. Adding to the findings revealed in the original papers by M.I. Tribelsky et al., the present review also reports several new analytical results, obtained as exact solutions to systems of coupled real Ginzburg–Landau (GL) equations. These are a new solution for symmetric DWs in the bimodal system including linear mixing between its components; a solution for a strongly asymmetric DWs in the case when the diffusion (second-derivative) term is present only in one GL equation; a solution for a system of three real GL equations, for the symmetric DW with a trapped bright soliton in the third component; and an exact solution for DWs between counter-propagating waves governed by the GL equations with group-velocity terms. The significance of the “old” and new results, collected in this review, is enhanced by the fact that the systems of coupled equations for two- and multicomponent order parameters, addressed in this review, apply equally well to modeling thermal convection, multimode light propagation in nonlinear optics, and binary Bose–Einstein condensates.

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