3,074 research outputs found
Staying in the zone: the cognitive components associated with offshore drillers' situation awareness.
Situation Awareness (SA) issues are often identified as contributing factors to drilling incidents, most recently in the Deepwater Horizon blowout. Two studies aimed to identify the cognitive components required for offshore drillers to develop and maintain SA whilst controlling subsea hydrocarbon wells. In study one, critical incident interviews were conducted with 18 experienced drilling personnel. Transcripts were subjected to thematic analysis, producing a framework of cognitive processes that enable drillers to build up an understanding of what is happening in the well bore and surrounding environment, predicting how the situation may develop. In the second study, analysis of 24 hours of observations (in-vivo and video) from a high fidelity well control simulator suggest behaviors such as monitoring and crew sharing information contribute to the drillers' SA. The findings highlight the importance of SA for safe and effective performance in drilling and are being used to develop a cognitive task analysis
Entrapment of Bacteria in Fluid Inclusions in Laboratory-Grown Halite
This is the publisher's version, also available electronically from "http://online.liebertpub.com".Cells of the bacterium Pseudomonas aeruginosa, which were genetically modified to produce green fluorescent protein, were entrapped in fluid inclusions in laboratory-grown halite. The bacteria were used to inoculate NaCl-saturated aqueous solutions, which were allowed to evaporate and precipitate halite. The number, size, and distribution of fluid inclusions were highly variable, but did not appear to be affected by the presence of the bacteria. Many of the inclusions in crystals from inoculated solutions contained cells in populations ranging from two to 20. Microbial attachment to crystal surfaces was neither evident nor necessary for entrapment. Cells occurred exclusively within fluid inclusions and were not present in the crystal matrix. In both the inclusions and the hypersaline solution, the cells fluoresced and twitched, which indicates that the bacteria might have remained viable after entrapment. The fluorescence continued up to 13 months after entrapment, which indicates that little degradation of the bacteria occurred over that time interval. The entrapment, fluorescence, and preservation of cells were independent of the volume of hypersaline solution used or whether the solutions were completely evaporated prior to crystal extraction. The results of this study have a wide range of implications for the long-term survival of microorganisms in fluid inclusions and their detection through petrography. The results also demonstrate the preservation potential for microbes in hypersaline fluid inclusions, which could allow cells to survive harsh conditions of space, the deep geologic past, or burial in sedimentary basins
A Comparison of Self-Control Measures and Drug and Alcohol Use among College Students
Research has shown a link between drug and alcohol behaviors and self-control; however, much of the research focuses on only the general theory of crime (Gottfredson and Hirschi 1990), without regard to Hirschi’s (2004) self-control theory. The purpose of the current study is to examine three measures of Hirschi’s self-control theory and to understand the link between Hirschi’s self-control theory and drug and alcohol behaviors. This study draws from a sample of undergraduate college students (N = 640) to examine the role of Hirschi’s self-control in the explanation of drug and alcohol behaviors. The current study uses a previous measure of Hirschi’s self-control [i.e., decisional self-control (alcohol)] and two measures (i.e., decisional self-control (cheat) and bond-based self-control) created by the researchers to analyze drug and alcohol behaviors. Results indicated that self-control based in social bonds (i.e., bond-based self-control) was significantly related to all drug and alcohol behaviors. The cost/salience scale measuring cheating behaviors [i.e., decisional self-control (cheat)] was significantly related to marijuana/hashish use, and the cost/salience scale measuring drinking and driving [i.e., decisional self-control (alcohol)] was significantly related to zero drug and alcohol behaviors. Results indicate that developing strong social bonds as a form of self-control can reduce the likelihood of drug and alcohol behaviors
A New High Contrast Imaging Program at Palomar Observatory
We describe a new instrument that forms the core of a long-term high contrast
imaging program at the 200-inch Hale Telescope at Palomar Observatory. The
primary scientific thrust is to obtain images and low-resolution spectroscopy
of brown dwarfs and young Jovian mass exoplanets in the vicinity of stars
within 50 parsecs of the Sun. The instrument is a microlens-based integral
field spectrograph integrated with a diffraction limited, apodized-pupil Lyot
coronagraph, mounted behind the Palomar adaptive optics system. The
spectrograph obtains imaging in 23 channels across the J and H bands (1.06 -
1.78 microns). In addition to obtaining spectra, this wavelength resolution
allows suppression of the chromatically dependent speckle noise, which we
describe. We have recently installed a novel internal wave front calibration
system that will provide continuous updates to the AO system every 0.5 - 1.0
minutes by sensing the wave front within the coronagraph. The Palomar AO system
is undergoing an upgrade to a much higher-order AO system ("PALM-3000"): a
3388-actuator tweeter deformable mirror working together with the existing
241-actuator mirror. This system will allow correction with subapertures as
small as 8cm at the telescope pupil using natural guide stars. The coronagraph
alone has achieved an initial dynamic range in the H-band of 2 X 10^-4 at 1
arcsecond, without speckle noise suppression. We demonstrate that spectral
speckle suppression is providing a factor of 10-20 improvement over this
bringing our current contrast at an arcsecond to ~2 X 10^-5. This system is the
first of a new generation of apodized pupil coronagraphs combined with
high-order adaptive optics and integral field spectrographs (e.g. GPI, SPHERE,
HiCIAO), and we anticipate this instrument will make a lasting contribution to
high contrast imaging in the Northern Hemisphere for years.Comment: Accepted to PASP: 12 pages, 12 figure
Estimation of Short-Term Tag-Induced Mortality in Horseshoe Crabs Limulus Polyphemus
Horseshoe crabs Limulus Polyphemus range along the East Coast of the United States and over 150,000 of them have been marked with U.S. Fish and Wildlife Service disk tags. It has been assumed that the tags do not harm the animals and are similar to common epibionts often found on the shells of the horseshoe crabs. We investigated whether newlv tagged adult female horseshoe crabs would exhibit higher short-term mortality rates than untagged adult females. All crabs were collected from a beach in Connecticut and then were transported to a laboratory for the experiment. Tagging involved drilling a small hole through the carapace in the lower back corner or the prosoma and then inserting the tag into the hole. Overall mortality of the tagged and untagged females held in flow-through raceways for 44 d was minimal (0% mortality among 53 tagged crabs; 4% mortality among 52 untagged crabs). None of the horseshoe crabs lost or shed their disk tags over the course of the experiment. In field mark-recapture studies of horseshoe crabs, typically between 11% and 20% of the initial numbers of tagged crabs are recaptured. Crabs that are recaptured but reported dead are unlikely to have died from the initial tagging process. Our results indicate that newly tagged adult horseshoe crabs have the potential to survive as well as untagged crabs through the Connecticut spawning season (~30-45 d). Recapture data also suggest that these crabs can survive for as long Its 8-10 years with the tags in place
Use of dynamic microsimulation to predict disease progression in patients with pneumonia-related sepsis
Know The Star, Know the Planet. IV. A Stellar Companion to the Host star of the Eccentric Exoplanet HD 8673b
HD 8673 hosts a massive exoplanet in a highly eccentric orbit (e=0.723).
Based on two epochs of speckle interferometry a previous publication identified
a candidate stellar companion. We observed HD 8673 multiple times with the 10 m
Keck II telescope, the 5 m Hale telescope, the 3.63 m AEOS telescope and the
1.5m Palomar telescope in a variety of filters with the aim of confirming and
characterizing the stellar companion. We did not detect the candidate
companion, which we now conclude was a false detection, but we did detect a
fainter companion. We collected astrometry and photometry of the companion on
six epochs in a variety of filters. The measured differential photometry
enabled us to determine that the companion is an early M dwarf with a mass
estimate of 0.33-0.45 M?. The companion has a projected separation of 10 AU,
which is one of the smallest projected separations of an exoplanet host binary
system. Based on the limited astrometry collected, we are able to constrain the
orbit of the stellar companion to a semi-major axis of 35{60 AU, an
eccentricity ? 0.5 and an inclination of 75{85?. The stellar companion has
likely strongly in uenced the orbit of the exoplanet and quite possibly
explains its high eccentricity.Comment: Accepted to the Astronomical Journal, 6 Pages, 5 Figure
Perinatal Air Pollutant Exposures and Autism Spectrum Disorder in the Children of Nurses’ Health Study II Participants
Objective: Air pollution contains many toxicants known to affect neurological function and to have effects on the fetus in utero. Recent studies have reported associations between perinatal exposure to air pollutants and autism spectrum disorder (ASD) in children. We tested the hypothesis that perinatal exposure to air pollutants is associated with ASD, focusing on pollutants associated with ASD in prior studies. Methods: We estimated associations between U.S. Environmental Protection Agency–modeled levels of hazardous air pollutants at the time and place of birth and ASD in the children of participants in the Nurses’ Health Study II (325 cases, 22,101 controls). Our analyses focused on pollutants associated with ASD in prior research. We accounted for possible confounding and ascertainment bias by adjusting for family-level socioeconomic status (maternal grandparents’ education) and census tract–level socioeconomic measures (e.g., tract median income and percent college educated), as well as maternal age at birth and year of birth. We also examined possible differences in the relationship between ASD and pollutant exposures by child’s sex. Results: Perinatal exposures to the highest versus lowest quintile of diesel, lead, manganese, mercury, methylene chloride, and an overall measure of metals were significantly associated with ASD, with odds ratios ranging from 1.5 (for overall metals measure) to 2.0 (for diesel and mercury). In addition, linear trends were positive and statistically significant for these exposures (p < .05 for each). For most pollutants, associations were stronger for boys (279 cases) than for girls (46 cases) and significantly different according to sex. Conclusions: Perinatal exposure to air pollutants may increase risk for ASD. Additionally, future studies should consider sex-specific biological pathways connecting perinatal exposure to pollutants with ASD
New portable tool to screen vestibular and visual function—National Institutes of Health Toolbox initiative
As part of the National Institutes of Health Toolbox initiative, we developed a low-cost, easy-to-administer, and time-efficient test of vestibular and visual function. A computerized test of dynamic visual acuity (cDVA) was used to measure the difference in visual acuity between head still and moving in yaw. Participants included 318 individuals, aged 3 to 85 years (301 without and 17 with vestibular pathology). Adults used Early Treatment of Diabetic Retinopathy Study (ETDRS) optotypes; children used ETDRS, Lea, and HOTV optotypes. Bithermal calorics, rotational chair, and light box testing were used to validate the cDVA. Analysis revealed that the cDVA test is reliable for static (intraclass correlation coefficient [ICC] \u3e/= 0.64) and dynamic (ICC \u3e/= 0.43–0.75) visual acuity. Children younger than 6 years old were more likely to complete cDVA with Lea optotypes, but reliability and correlation with ETDRS was better using HOTV optotypes. The high correlation between static acuity and light box test scores (r = 0.795), significant difference of cDVA scores between those with and without pathology (
Electric Field Conjugation with the Project 1640 coronagraph
The Project 1640 instrument on the 200-inch Hale telescope at Palomar
Observatory is a coronagraphic instrument with an integral field spectrograph
at the back end, designed to find young, self-luminous planets around nearby
stars. To reach the necessary contrast for this, the PALM-3000 adaptive optics
system corrects for fast atmospheric speckles, while CAL, a phase-shifting
interferometer in a Mach-Zehnder configuration, measures the quasistatic
components of the complex electric field in the pupil plane following the
coronagraphic stop. Two additional sensors measure and control low-order modes.
These field measurements may then be combined with a system model and data
taken separately using a white-light source internal to the AO system to
correct for both phase and amplitude aberrations. Here, we discuss and
demonstrate the procedure to maintain a half-plane dark hole in the image plane
while the spectrograph is taking data, including initial on-sky performance.Comment: 9 pages, 7 figures, in Proceedings of SPIE, 8864-19 (2013
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