National Educators' Workshop: Update 1988. Standard Experiments in Engineering Materials Science and Technology

Presented here is a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 88, held May 10 to 12, 1988 at the National Institute of Standards and Technology (NIST), Gaithersberg, Maryland. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community

National Educators' Workshop: Update 1989 Standard Experiments in Engineering Materials Science and Technology

Presented here is a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 89, held October 17 to 19, 1989 at the National Aeronautics and Space Administration, Hampton, Virginia. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community

Distribution of Bats in the Delta Region of Northeastern Arkansas

Eight taxa of bats are reported from seven counties in northeastern Arkansas. Localities, natural history notes, sex, age and reproductive condition are reported for most species. New records are combined with previously existing ones to reveal a greater distribution of chiroptera for the stat

National Educators' Workshop: Update 1991. Standard Experiments in Engineering Materials Science and Technology

Given here is a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 91, held at the Oak Ridge National Laboratory on November 12-14, 1991. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community

Loads and Aeroelasticity Division research and technology accomplishments for FY 1986 and plans for FY 1987

The Loads and Aeroelasticity Division's research accomplishments for FY 86 and research plans for FY 87 are presented. The work under each Branch (technical area) is described in terms of highlights of accomplishments during the past year and highlights of plans for the current year as they relate to five year plans for each technical area. This information will be useful in program coordination with other government organizations and industry in areas of mutual interest

Space Transportation Materials and Structures Technology Workshop

The Space Transportation Materials and Structures Technology Workshop was held on September 23-26, 1991, in Newport News, Virginia. The workshop, sponsored by the NASA Office of Space Flight and the NASA Office of Aeronautics and Space Technology, was held to provide a forum for communication within the space materials and structures technology developer and user communities. Workshop participants were organized into a Vehicle Technology Requirements session and three working panels: Materials and Structures Technologies for Vehicle Systems, Propulsion Systems, and Entry Systems

Age-Related Changes in Attention During Motor Learning

Theories of motor learning predict that humans require high levels of attention to perform new motor tasks, but little to no attention for those that are well-learned. Thus, practicing a task may decrease the amount of attention required to perform it. To test this theoretical relationship between attention and task practice, we used a physiological proxy for attention known as electrodermal activity (EDA). We hypothesized that 1) EDA (proxy for attention) would decrease over the course of training and that 2) attention would be higher overall in older adults than in younger adults when performing the same task. This second hypothesis was based on the tendency for older adults to require more attention than younger adults during a given motor task. Two groups of participants (young adult- n=S; mean± SD age=22.4 ± 2.1 yrs vs. older adult- n=S; age=75.8 ± 5.2 yrs) practiced 150 trials of a novel upper extremity task over three days. During each trial, we measured 1) task performance, defined as movement time (seconds, ors) and 2) EDA (μSiemens, or μS) using wrist-worn sensors. Contrary to our first hypothesis, EDA increased with practice, suggesting that additional training may be necessary to reduce the task\u27 s attentional requirements. Results did, however, support our second hypothesis, with higher EDA in older adults compared to younger adults throughout practice. This suggests that older adults may use more attention than younger adults to perform a given task in order to compensate for other age-related declines in sensorimotor function

Revolution, Reform, and Reticent Voices: The Effects of Nicaragua\u27s Dynamic Health System on Medical Professionals

The views of health professionals are an important and often overlooked aspect of changes in health policy. This paper examines the impact of healthcare reform on the medical professionals of Nicaragua over the last 40 years. First, the historical context of Nicaraguan healthcare is discussed. This history is presented as both an outgrowth of and a reaction to Nicaragua’s changing political environment. The changes in health policy over this time period are then examined through the lens of medical professionals. Several sub-topics are investigated including the relationship between perceptions of health professionals and political ideology, the inability of the younger generation to express their views of healthcare reform, and how perceptions of healthcare reform relate to overall job satisfaction

Experimental Constraints on Degassing and Permeability in Volcanic Conduit Flow.

This study assesses the effect of decompression rate on two processes that directly influence the behavior of volcanic eruptions: degassing and permeability in magmas. We studied the degassing of magma with experiments on hydrated natural rhyolitic glass at high pressure and temperature. From the data collected, we defined and characterized one degassing regime in equilibrium and two regimes in disequilibrium. Equilibrium bubble growth occurs when the decompression rate is slower than 0.1 MPa s-1, while higher rates cause porosity to deviate rapidly from equilibrium, defining the first disequilibrium regime of degassing. If the deviation is large enough, a critical threshold of super-saturation is reached and bubble growth accelerates, defining the second disequilibrium regime. We studied permeability and bubble coalescence in magma with experiments using the same rhyolitic melt in open degassing conditions. Under these open conditions, we observed that bubbles start to coalesce at ~43 vol.% porosity, regardless of decompression rate. Coalescence profoundly affects bubble texture and size distributions, and induces the melt to become permeable. We parameterized and incorporated our experimental results into a 1D conduit flow model to explore the implications of our findings on eruptive behavior of rhyolitic melts with low crystal contents stored in the upper crust. Compared to previous models that assume equilibrium degassing of the melt during ascent, the introduction of disequilibrium degassing reduces the deviation from lithostatic pressure by ~ 25 %, the acceleration at high porosities (> 50 vol.%) by a factor 5, and the associated decompression rate by an order of magnitude. The integration of the time scale of coalescence to the model shows that the transition between explosive and effusive eruptive regimes is sensitive to small variations of the initial magma ascent speed, and that flow conditions near fragmentation may significantly be affected by bubble coalescence and gas escape

The limits of spatial resolution achievable using a 30kHz multibeam sonar: model predictions and field results

A Simrad EM300 multibeam sonar was used to attempt to resolve small (-5m high) targets in 450m of water. The targets had previously been surveyed using a deeply towed 59 kHz sidescan sonar. Using multisector active yaw, pitch and roll compensation, together with dynamically altering angular sectors, the sonar is capable of maintaining sounding densities of as tight as 10m spacing in these water depths. This is significantly smaller than the largest dimension of the projected beam footprints (1 6-64m). The observed data suggest that the targets are intermittently resolved. The field results compare well to the output of a numerical model which reproduces the imaging geometry. Possible variations in the imaging geometry are implemented in the model, comparing equiangular and equidistant beam spacings, differing angular sectors and all the different combinations of transmit and receive beam widths that are available for this model of sonar. While amplitude detection is significantly aliased by targets smaller than the across track beam footprint, under conditions where the signal to noise ratio is favorable, phase detection can be used to reduce the minimum size of target observed to about the scale of the across track beam width. Thus having the beam spacing at the scale is justifiable. The phase distortion due to smaller targets, however, is generally averaged out