Effect of microgravity on several visual functions during STS shuttle missions

Changes in the acuity of astronaut vision during flight are discussed. Parameters such as critical flicker vision, stereopsis to 10 seconds of arc, visual acuity in small steps to 20/7.7, cyclophoria, lateral and vertical phoria and retinal rivalry were tested using a visual function tester. Twenty-three Space Transportation System (STS) astronauts participated in the experiments. Their vision was assessed twice before launch and after landing, and three to four times while on-orbit and landing. No significant differences during space flight were observed for any of the visual parameters tested. In some cases, slight changes in acuity and stereopsis were observed with a subsequent return to normal vision after flight

Driving self-restriction and age: A study of emergency department patients

BACKGROUND: Driving self-restriction is well-documented among older drivers but might also occur among younger drivers. Little is known about the driving patterns of emergency department (ED) patients, who may be a high-risk population for motor vehicle crashes (MVCs). We sought to compare the driving patterns and MVCs of younger and older adult ED patients in order to inform development of injury prevention interventions in EDs. METHODS: We surveyed English-speaking younger adult (age 25–64) and older adult (age ≥65) ED patients, excluding non-drivers and those who were cognitively-impaired or too sick to participate. We compared drivers by age group and used logistic regression with adjustment for driving frequency to examine factors associated with driving self-restriction. RESULTS: Of those eligible, 82% (n = 178) of younger adult and 91% (n = 134) of older adult patients participated; approximately half were women. Similar proportions of younger and older adult patients reported driving everyday/almost everyday (80%) but also self-restricting driving in inclimate weather (48%), heavy traffic (27%), in unfamiliar places (21%), when travelling with passengers (1.6%) or when alone (1.3%). Fewer younger adult than older adult patients avoided driving at night (22% versus 49%) or on highways (6.7% versus 26%). In multivariable logistic regression, factors significantly associated self-imposed driving restriction in ≥1 driving situation were female gender (Odds Ratio [OR] 2.40; 95% CI 1.42-4.05) and ever feeling “confused, nervous or uncomfortable” while driving (OR 1.87; 95% CI 1.03-3.39). There was a non-significant trend for differences in proportions between younger adult (11%) and older adult (6.8%) drivers reporting ≥1 MVC as a driver in the past 12 months. CONCLUSIONS: Similar proportions of younger and older adult ED patients self-restrict driving, albeit in different situations, which has implications for behavioral interventions for injury prevention and for education of patients and medical providers. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40621-014-0018-z) contains supplementary material, which is available to authorized users

Effect of microgravity on visual contrast threshold during STS Shuttle missions: Visual Function Tester-Model 2 (VFT-2)

Viewgraphs on effect of microgravity on visual contrast threshold during STS shuttle missions are presented. The purpose, methods, and results are discussed. The visual function tester model 2 is used

The (C-H) bond dissociation energy in the methyl group of toluene

A, kinetic study of the pyrolysis of toluene by a flow technique has been made, and assuming Szwarc\u27s mechanism, two activation energies (78.3 and 84 kcal/mole depending on the temperature range used) have been derived for the dissociation of the (C-H) bond in the methyl group of toluene. The lower value agrees quite well with Szwarc\u27s, and the higher value turns out to be approximately the average of 77.5 and 89.9. The results of this research suggest 84 kcal/mole as the upper limit for the activation energy

Blast waves from violent explosive activity at Yasur Volcano, Vanuatu

Infrasonic and seismic waveforms were collected during violent strombolian activity at Yasur Volcano (Vanuatu). Averaging similar to 3000 seismic events showed stable waveforms, evidencing a low-frequency (0.1-0.3Hz) signal preceding similar to 5-6s the explosion. Infrasonic waveforms were mostly asymmetric with a sharp compressive (5-106Pa) onset, followed by a small long-lasting rarefaction phase. Regardless of the pressure amplitude, the ratio between the positive and negative phases was constant. These waveform characteristics closely resembled blast waves. Infrared imagery showed an apparent cold spherical front similar to 20 m thick, which moved between 342 and 405m/s before the explosive hot gas/fragments cloud. We interpret this cold front as that produced by the vapor condensation induced by the passage of the shock front. We suggest that violent strombolian activity at Yasur was driven by supersonic dynamics with gas expanding at 1.1 Mach number inside the conduit

Forecasting Effusive Dynamics and Decompression Rates by Magmastatic Model at Open-vent Volcanoes

Effusive eruptions at open-conduit volcanoes are interpreted as reactions to a disequilibrium induced by the increase in magma supply. By comparing four of the most recent effusive eruptions at Stromboli volcano (Italy), we show how the volumes of lava discharged during each eruption are linearly correlated to the topographic positions of the effusive vents. This correlation cannot be explained by an excess of pressure within a deep magma chamber and raises questions about the actual contributions of deep magma dynamics. We derive a general model based on the discharge of a shallow reservoir and the magmastatic crustal load above the vent, to explain the linear link. In addition, we show how the drastic transition from effusive to violent explosions can be related to different decompression rates. We suggest that a gravity-driven model can shed light on similar cases of lateral effusive eruptions in other volcanic systems and can provide evidence of the roles of slow decompression rates in triggering violent paroxysmal explosive eruptions, which occasionally punctuate the effusive phases at basaltic volcanoes

Dielectric nano-antennas for strain engineering in atomically thin two-dimensional semiconductors

Atomically thin two-dimensional semiconducting transition metal dichalcogenides (TMDs) can withstand large levels of strain before their irreversible damage occurs. This unique property offers a promising route for control of the optical and electronic properties of TMDs, for instance by depositing them on nano-structured surfaces, where position-dependent strain can be produced on the nano-scale. Here, we demonstrate strain-induced modifications of the optical properties of mono- and bilayer TMD WSe$_2$ placed on photonic nano-antennas made from gallium phosphide (GaP). Photoluminescence (PL) from the strained areas of the TMD layer is enhanced owing to the efficient coupling with the confined optical mode of the nano-antenna. Thus, by following the shift of the PL peak, we deduce the changes in the strain in WSe$_2$ deposited on the nano-antennas of different radii. In agreement with the presented theory, strain up to $\approx 1.4 \%$ is observed for WSe$_2$ monolayers. We also estimate that $>3\%$ strain is achieved in bilayers, accompanied with the emergence of a direct bandgap in this normally indirect-bandgap semiconductor. At cryogenic temperatures, we find evidence of the exciton confinement in the most strained nano-scale parts of the WSe$_2$ layers, as also predicted by our theoretical model. Our results, of direct relevance for both dielectric and plasmonic nano-antennas, show that strain in atomically thin semiconductors can be used as an additional parameter for engineering light-matter interaction in nano-photonic devices

High-throughput multimodal wide-field Fourier-transform Raman microscope

Raman microscopy is a powerful analytical technique for materials and life sciences that enables mapping the spatial distribution of the chemical composition of a sample. State-of-the-art Raman microscopes, based on point-scanning frequency-domain detection, have long (∼1 s) pixel dwell times, making it challenging to acquire images of a significant area (e.g., 100×100 μm). Here we present a compact wide-field Raman microscope based on a time-domain Fourier-transform approach, which enables parallel acquisition of the Raman spectra on all pixels of a 2D detector. A common-path birefringent interferometer with exceptional delay stability and reproducibility can rapidly acquire Raman maps (∼30 min for a 250 000 pixel image) with high spatial (<1 μm) and spectral (∼23 cm-1) resolutions. Time-domain detection allows us to disentangle fluorescence and Raman signals, which can both be measured separately. We validate the system by Raman imaging plastic microbeads and demonstrate its multimodal operation by capturing fluorescence and Raman maps of a multilayer-WSe2 sample, providing complementary information on the strain and number of layers of the material