6,420 research outputs found
The Effect of Loving-Kindness Meditation on Physiological and Psychological Reactions to Violent Stimuli
In the past, meditation research has focused primarily on mindfulness meditation, but little research has examined Loving-Kindness Meditation (LKM). LKM may be an important addition to treatment or preventative programs for people at risk of exposure to violence or aggression in their lives or work. The current research aims to add to the currently growing body of literature concerning LKM and compassion based meditation practices. The researchers sought to determine if a 12-week course in LKM would have any effect on galvanic skin response (GSR) and heart rate in beats per minute (BPM) during the presentation of a video containing violent imagery of individuals engaged in physical altercations. Specifically, the current study sought to answer the following questions: (1) do GSR and BPM increase during the viewing of violent stimuli after a course in LKM, (2) do participants in the LKM group return to baseline on GSR and BPM measures more rapidly after a course in LKM than controls, and (3) are there any significant changes in measures of psychological factors after a course in LKM relative to individuals’ baseline. While the results for the physiological measures were not significant they did offer information that may prove valuable for future research. Several psychological measures were significant or trended toward significant outcomes indicating the need for further research in this area suggesting a relationship between LKM and physiological states. Taken together the results of this study indicate that the LKM course may have sensitized participants to the concerns of others as well as their own emotional states
Numerical prediction of transition of the F-16 wing at supersonic speeds
A parametric study is being conducted as an effort to numerically predict the extent of natural laminar flow (NLF) on finite swept wings at supersonic speeds. This study is one aspect of a High Speed Research Program (HSRP) to gain an understanding of the technical requirements for high-speed aircraft flight. The parameters that are being addressed in this study are Reynolds number, angle of attack, and leading-edge wing sweep. These parameters were analyzed through the use of an advanced Computational Fluid Dynamics (CFD) flow solver, specifically the ARC 3-D Compressible Navier-Stokes (CNS) flow solver. From the CNS code, pressure coefficients (Cp) are obtained for the various cases. These Cp's are then used to compute the boundary-layer profiles through the use of the 'Kaups and Cebeci' compressible 2-D boundary layer code. Finally, the boundary-layer parameters are processed into a 3-D compressible boundary layer stability code (COSAL) to predict transition. The parametric study then consisted of four geometries which addressed the effects of sweep, and three angles of attack from zero to ten degrees to yield a total of 12 cases. The above process was substantially automated through a procedure that was developed by the work conducted under this study. This automation procedure then yields a 3-D graphical measure of the extent of laminar flow by predicting the transition location of laminar to turbulent flow
Late Life Depressive Symptoms and Cognitive Function among Older Mexican Adults: The Past and the Present
Objective: To evaluate associations between depression and individual cognitive domains and how changes in depressive symptoms relate to cognition three years later in the context of Mexico, a developing country experiencing rapid aging.
Method: Data comes from waves 3 (2012) and 4 (2015) of the Mexican Health and Aging Study (n=12,898, age 50+). Depression is ascertained using a modified Center for Epidemiologic Studies – Depression Scale. Cognition is assessed using verbal learning, verbal memory, visual scanning, verbal fluency, visuospatial ability, visual memory, and orientation tasks. Depressive symptoms and cognitive functioning were both measured in 2012 and 2015. Scores across cognitive domains are modeled using ordinary least squares regression, adjusting for demographic, health, and economic covariates.
Results: When depression and cognition were measured concurrently in 2015, depression exhibited associations with all cognitive domains. When considering a respondent’s history of depression, individuals who had elevated depressive symptoms in 2012 and recovered by 2015 continued to exhibit poorer cognitive function in 2015 in verbal learning, verbal memory, visual scanning, and verbal fluency tasks compared to individuals who were neither depressed in 2012 nor 2015.
Conclusions: Depression was associated with cognition across cognitive domains among older Mexican adults. Despite improvements in depressive symptomatology, formerly depressed respondents continued to perform worse than their counterparts without a history of depression on several cognitive tasks. In addition to current mental health status, researchers should consider an individual’s history of depression when assessing the cognitive functioning of older adults
Canopy CO2 exchange of two neotropical tree species exhibiting constitutive and facultative CAM photosynthesis, Clusia rosea and Clusia cylindrica
Photon flux density (PFD) and water availability, the daily and seasonal factors that vary most in tropical environments, were examined to see how they influenced expression of crassulacean acid metabolism (CAM) in 3-year-old Clusia shrubs native to Panama. Instead of the commonly used single-leaf approach, diel CO2 exchange was measured for whole individual canopies of plants in large soil containers inside a naturally illuminated 8.8 m3 chamber. In well-watered C. rosea, a mainly constitutive CAM species, nocturnally fixed CO2 contributed about 50% to 24 h carbon gain on sunny days but the contribution decreased to zero following overcast days. Nonetheless, CO2 fixation in the light responded in such a way that 24 h carbon gain was largely conserved across the range of daily PFDs. The response of C. rosea to drought was similarly buffered. A facultative component of CAM expression led to reversible increases in nocturnal carbon gain that offset drought-induced reductions of CO2 fixation in the light. Clusia cylindrica was a C3 plant when well-watered but exhibited CAM when subjected to water stress. The induction of CAM was fully reversible upon rewatering. C. cylindrica joins C. pratensis as the most unambiguous facultative CAM species reported in the genus Clusia
Re-entry vehicle shape for enhanced performance
A convex shell structure for enhanced aerodynamic performance and/or reduced heat transfer requirements for a space vehicle that re-enters an atmosphere. The structure has a fore-body, an aft-body, a longitudinal axis and a transverse cross sectional shape, projected on a plane containing the longitudinal axis, that includes: first and second linear segments, smoothly joined at a first end of each the first and second linear segments to an end of a third linear segment by respective first and second curvilinear segments; and a fourth linear segment, joined to a second end of each of the first and second segments by curvilinear segments, including first and second ellipses having unequal ellipse parameters. The cross sectional shape is non-symmetric about the longitudinal axis. The fourth linear segment can be replaced by a sum of one or more polynomials, trigonometric functions or other functions satisfying certain constraints
Formation in-situ of metallic nanoclusters of Mn interlayered into bentonite previously pillared with Al
Hasta el momento, el crecimiento de agregados polinucleares en el espacio interlaminar de diferentes aluminosilicatos por reacción en el estado sólido requiere de tiempos prolongados de contacto (alrededor de 4 meses). En consecuencia, en el presente trabajo se ha evaluado una metodología novedosa para llevar a cabo tal síntesis, específicamente para el crecimiento in-situ de MnS en el espacio interlaminar de una bentonita que involucra un tiempo aproximado de 10 horas de reacción. Sin embargo, los resultados han evidenciado que hay varias condiciones que se deben controlar por cuanto afectan la estabilidad de los clusters; entre estos factores están el tratamiento químico, térmico, el tipo de atmósfera empleado en la calcinación y la densidad de los pilares de Al
Human Mars Entry, Descent, and Landing Architecture Study: Phase 3 Summary
Over the past four years, NASA has directed the Entry, Descent and Landing Architecture Study (EDLAS) to evaluate candidate technologies to deliver human-scale vehicles (carrying 20t payloads) to the surface of Mars. The study focused on two vehicles in Phase 3 (during 2018 and 2019), one low and one mid lift-to-drag (L/D) vehicle. This paper summarizes updates to the structural and aeroshell outer mold line design for the mid-L/D Mars entry lander vehicle that occurred during EDLAS Phase 3. The design efforts used parametric optimization to arrive at a solution for total vehicle primary and secondary structure mass, and vehicle center-of-gravity location. Additionally, the end of Phase 2 provided an updated surface payload manifest that required three 22 t landers. This paper also summarizes the results of the packaging feasibility study of the updated payload configurations for those three reference missions. The study verified an arrangement of the payload elements within the mid-L/D vehicle that satisfied the center of gravity location limitations for flight
Spitzer Warm Mission Transition and Operations
Following the successful dynamic planning and implementation of IRAC Warm Instrument Characterization activities, transition to Spitzer Warm Mission operations has gone smoothly. Operation teams procedures and processes required minimal adaptation and the overall composition of the Mission Operation System retained the same functionality it had during the Cryogenic Mission. While the warm mission scheduling has been simplified because all observations are now being made with a single instrument, several other differences have increased the complexity. The bulk of the observations executed to date have been from ten large Exploration Science programs that, combined, have more complex constraints, more observing requests, and more exo-planet observations with durations of up to 145 hours. Communication with the observatory is also becoming more challenging as the Spitzer DSN antenna allocations have been reduced from two tracking passes per day to a single pass impacting both uplink and downlink activities. While IRAC is now operating with only two channels, the data collection rate is roughly 60% of the four-channel rate leaving a somewhat higher average volume collected between the less frequent passes. Also, the maximum downlink data rate is decreasing as the distance to Spitzer increases requiring longer passes. Nevertheless, with well over 90% of the time spent on science observations, efficiency has equaled or exceeded that achieved during the cryogenic mission
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