Odors: from chemical structures to gaseous plumes

We are immersed within an odorous sea of chemical currents that we parse into individual odors with complex structures. Odors have been posited as determined by the structural relation between the molecules that compose the chemical compounds and their interactions with the receptor site. But, naturally occurring smells are parsed from gaseous odor plumes. To give a comprehensive account of the nature of odors the chemosciences must account for these large distributed entities as well. We offer a focused review of what is known about the perception of odor plumes for olfactory navigation and tracking, which we then connect to what is known about the role odorants play as properties of the plume in determining odor identity with respect to odor quality. We end by motivating our central claim that more research needs to be conducted on the role that odorants play within the odor plume in determining odor identity

Magnetic cloud distortion resulting from propagation through a structured solar wind: Models and observations

Numerical simulations of magnetic clouds (MCs) propagating through a structured solar wind suggest that MC-associated magnetic flux ropes are highly distorted by inhomogeneities in the ambient medium. In particular, a solar wind configuration of fast wind from high latitudes and slow wind at low latitudes, common at periods close to solar minimum, should distort the cross section of magnetic clouds into concave-outward structures. This phenomenon has been reported in observations of shock front orientations, but not in the body of magnetic clouds. In this study an analytical magnetic cloud model based upon a kinematically distorted flux rope is modified to simulate propagation through a structured medium. This new model is then used to identify specific time series signatures of the resulting concave-outward flux ropes. In situ observations of three well studied magnetic clouds are examined with comparison to the model, but the expected concave-outward signatures are not present. Indeed, the observations are better described by the convex-outward flux rope model. This may be due to a sharp latitudinal transition from fast to slow wind, resulting in a globally concave-outward flux rope, but with convex-outward signatures on a local scale

Ocean Wave-Coherent Temperature and Humidity Near-Surface Vertical Distributions and Their Effect on Radar Performance over the Ocean

Large knowledge gaps concerning the effect of ocean surface waves on near-surface vertical distributions of temperature and humidity in the marine atmospheric surface layer exist due to practical limitations and sensor fidelity challenges of direct measurements. Wave effects on these distributions between the wave trough and crest are least studied within the literature. These scalar distributions influence atmospheric refractivity, which can lead to anomalous propagation of electromagnetic energy. Measurements of temperature and humidity are classically made using rocket- or radiosondes and fixed weather stations, and can utilize tethered profiling systems. However, these measurement systems have limitations when obtaining measurements near the sea surface. Consequently, boundary layer similarity models (i.e., Monin Obuhkov (MO) theory) are commonly employed to fill in these near-surface measurement gaps despite the documented shortcomings of these models in this region. To address this observational gap, this research develops a novel near-surface wave-coherent instantaneous profiling system (NWIPS) to aid in enriching our current knowledge regarding the influence of waves on near-surface vertical scalar distributions. Eighty minutes of wave-coherent instantaneous vertical scalar distributions were measured by NWIPS in an unstable atmosphere. It is the first attempt to obtain high resolution, wave-coherent vertical distributions of temperature and humidity within the lowest 3 m of altitude. Utilizing these measurements, the variability of near-surface vertical scalar distributions is investigated. These results are discussed in the context of their impact on propagation loss predictions for X-band and K-band frequencies. Comparisons between classical MO theory profiles and NWIPS measured profiles showed disagreement below 4 m, whereas above this altitude, there was good agreement. Comparisons between PL predictions for the two refractivity profiles revealed lower propagation loss at long range for MO theory, and differences are most significant for K-band. Below 4 m, distinct, persistent, vertical structure in both ten-minute and 80-minute ensembles and 80-minute wave phase-averaged vertical scalar profiles were observed. The complex structure in the mean temperature vertical distribution near the surface is consistent with prior laboratory and numerical studies. Variations in refractivity over wave phase showed the primary difference between refractivity profiles at the crest, trough, upslope, and downslope was the vertical shifting of the profiles resulting from the shifting surface. The phase-averaged profiles were also found to be steady over the 80-minute experiment consistent with the similar wave conditions during this time. The differences in the refractivity profiles for the various wave phases are shown to be relatively insignificant to X-band propagation predictions, while for K-band some discrepancies are observed over both flat and wavy surfaces. The differences resulting from the duct height shifting in range and/or the introduction of a wavy surface causes larger differences in propagation predictions than do changes in the refractivity profile with phase

Characterization of a Turbulent Boundary Layer in Open Channel Flow Using Particle Image Velocimetry

Turbulent boundary layers are influential in numerous applications (e.g. naval architecture, ocean engineering, sediment transport, etc.), yet considerable knowledge gaps still exist. Boundary layers are regions where transfer of mass, momentum, energy, and heat occur within the interface between a fluid and a solid, or between two fluids. Utilization of optical flow measurement techniques to measure the velocity field with high spatial resolution enables non-intrusive investigation of the complex fluid dynamics of boundary layers. In this study two-dimensional Particle Image Velocimetry was employed to investigate, primarily, the overlap layer of a turbulent boundary layer developed in the recirculating flume facility located in the Environmental Fluids Laboratory at Coastal Carolina University. Three locations in the streamwise direction and two locations in the spanwise direction were investigated covering a range of Reynolds numbers, 〖Re〗_D = 32,432 - 65,586. The overarching goal of this research was to i) investigate the flow characteristics of turbulent boundary layers in open channel flow and ii) provide benchmark results for future studies conducted in this facility. We calculated from the two measured velocity components (streamwise and vertical) over two spatial dimensions (streamwise and vertical) various mean flow and turbulent quantities. Results for the facility indicated: i) a distinct overlap layer existed between ~100 \u3c y+\u3c ~400, ii) a shape-factor characteristic of a zero-pressure gradient boundary layer, iii) turbulent intensity is relatively constant over the range of 〖Re〗_D (4-10%), iv) peak of TKE production occurred at the lower limit of the overlap layer and iv) free-surface effects influenced flow up to 20% of the water depth below the surface. Based on results and findings in this study, users should conduct experiments along the channel middle to avoid the influence of sidewalls, between 40-80% of the water height to perform measurements in the region of lowest turbulence intensity, and between 0-40% of the water height to perform turbulent boundary layer measurements

Energy cost and knee extensor strength changes following multiple day military load carriage.

Military exercises and recruit training requires soldiers, including new recruits, to undergo multiple days of substantial physical stress. The aim of this study was to evaluate the physiological impact of multiple days of military load carriage by addressing the hypothesis: A second day of load carriage increases oxygen uptake and reduces knee extensor torque compared to a single day of load carriage. A load carriage group (n = 12) (carrying 32 kg) and unloaded group (n = 14) walked on a treadmill for 2 h on two consecutive days. Knee extensor and flexor torque were assessed by dynamometry at speeds of: 0°·s ,60°·s and 180°·s before and after load carriage on day one and two, and 24 h following day 2. Oxygen uptake was assessed via respiratory gas assessment at the 6th and 119th minute of load carriage on day one and two. When assessed by mixed methods ANOVA (alpha: 0.05), an interaction effect was observed for oxygen uptake (p < 0.001), with post hoc assessment highlighting second day of load carriage significantly increased oxygen uptake compared to day one post in the loaded group (28.9(3.0) vs 25.8(3.4), p = 0.048). An interaction effect was observed for all knee extensor variables (all p < 0.05). All knee extensor peak torque variables were significantly associated to oxygen uptake at 0°s (r = -0.576, p < 0.05), 60°s (r = -0.552, p < 0.05), and 180°s (r = -0.589, p < 0.05). Two days of load carriage significantly increases oxygen uptake and reduces knee extensor and flexor torque compared to a single day of load carriage. Subsequently, physical training programmes aimed at increasing knee extensor strength may protect against increases in oxygen uptake. [Abstract copyright: Copyright © 2021 Elsevier Ltd. All rights reserved.

Game Over for Regulating Violent Video Games? The Effect of Brown v. Entertainment Merchants Ass’n on First Amendment Jurisprudence

As early as 1976, video games started to incorporate aspects of violence, such as striking enemies with a vehicle or using explosives to destroy a structure. Still, initially, courts were reluctant to assign the same constitutional protections to video games that they had granted to other protected media like motion pictures and written and musical works. But as technology progressed, courts, too, matured, becoming more open to the notion that video games should be a form of protected expression. Yet, some courts lost sight of the First Amendment’s vision and reconsidered their earlier decisions in which they upheld the constitutionality of video game expression. This prompted the U.S. Supreme Court, in the first case that dealt with the First Amendment’s protection of video games, to remedy nearly four decades of confusion and unify the law in Brown v. Entertainment Merchants Ass’n. After the Court’s decision in Brown, it is safe to assume that, at society’s current level of technological progress, courts are likely to hold that children’s use of video games is expressive conduct that the First Amendment protects. But if technology becomes “too advanced” and mechanics such as virtual reality, three-dimensional space, and infrared movement simulators become the technological norm, the Court may have to reexamine its reasoning in Brown before too long