Neurophysiological responses to stressful motion and anti-motion sickness drugs as mediated by the limbic system

Performance is characterized in terms of attention and memory, categorizing extrinsic mechanism mediated by ACTH, norepinephrine and dopamine, and intrinsic mechanisms as cholinergic. The cholinergic role in memory and performance was viewed from within the limbic system and related to volitional influences of frontal cortical afferents and behavioral responses of hypothalamic and reticular system efferents. The inhibitory influence of the hippocampus on the autonomic and hormonal responses mediated through the hypothalamus, pituitary, and brain stem are correlated with the actions of such anti-motion sickness drugs as scopolamine and amphetamine. These drugs appear to exert their effects on motion sickness symptomatology through diverse though synergistic neurochemical mechanisms involving the septohippocampal pathway and other limbic system structures. The particular impact of the limbic system on an animal's behavioral and hormonal responses to stress is influenced by ACTH, cortisol, scopolamine, and amphetamine

Estimation of Proportions of Objects and Determination of Training Sample-Size in a Remote Sensing Application

One of the problems in remote sensing is estimating the expected proportions of certain categories of objects which cannot be observed directly or distinctly. For example, a multi-channel scanning device may fail to observe objects because of obstructions blocking the view, or different categories of objects may make up a resolution element giving rise to a single observation. This will require ground truth on any such categories of objects for estimating their expected proportions associated with various classes represented in the remote sensing data. Considering the classes to be distributed as multivariate normal with different mean vectors and common covariance, we give the maximum likelihood estimates for the expected proportions of objects associated with different classes, using the Bayes procedure for classification of individuals obtained from these classes. An approximate solution for simultaneous confidence intervals on these proportions is given, and thereby a sample-size needed to achieve a desired amount of accuracy for the estimates has been determined

The Impact of PBL as a STEM School Reform Model

Project/problem-based learning (PBL) can provide an effective model for school reform when implemented with fidelity. In the report, Rising Above the Gathering Storm, it was recommended that if the U.S. is to remain competitive in the 21st-century economy, there must be a serious effort to “enlarge the pipeline of students who are prepared to enter college and graduate with a degree in STEM” (National Academy of Sciences, National Academy of Engineering, & Institute of Medicine, 2007, p. 6). The report included the recommendation that states develop statewide specialty STEM high schools (National Academy of Sciences, National Academy of Engineering, & Institute of Medicine, 2007, p. 6). In 2010, the Texas Science, Technology, Engineering, and Mathematics Academy (T-STEM) initiative was implemented to develop specialty STEM schools similar to those described in Rising Above the Gathering Storm. The primary instructional strategy of T-STEM academies is problem- and project-based learning. In the STEM context, PBL is well suited as a primary pedagogy for STEM learning. This paper examines the following questions: What outcomes occur when PBL is implemented in a low performing school district? What is the role of PBL in school improvement? What are the challenges to implementing PBL with high fidelity

Measuring X-Ray Polarization in the Presence of Systematic Effects

We describe a mathematical formalism for determining the 1 and 2 parameter errors in the magnitude and position angle of X ]ray polarization. The formalism includes a treatment of systematic effects, such as background and instrumental bias

Advanced X-ray Astrophysics Facility (AXAF): An overview

The Advanced X-ray Astrophysics Facility (AXAF) is the x-ray component of NASA's Great Observatories. To be launched in late 1998, AXAF will provide unprecedented capabilities for high-resolution imaging, spectrometric imaging, and high-resolution disperse spectroscopy, over the x-ray band from about 0.1 keV to 10 keV. With these capabilities, AXAF observations will address many of the outstanding questions in astronomy, astrophysics, and cosmology

The Age of Cluster Galaxies from Continuum Colors

We determine the age of 1,104 early-type galaxies in eight rich clusters ($z = 0.0046$ to $0.175$) using a new continuum color technique. We find that galaxies in clusters divide into two populations, an old population with a mean age similar to the age of the Universe (12 Gyrs) and a younger population with a mean age of 9 Gyrs. The older population follows the expected relations for mass and metallicity that imply a classic monolithic collapse origin. Although total galaxy metallicity is correlated with galaxy mass, it is uncorrelated with age. It is impossible, with the current data, to distinguish between a later epoch of star formation, longer duration of star formation or late bursts of star formation to explain the difference between the old and young populations. However, the global properties of this younger population are correlated with cluster environmental factors, which implies secondary processes, post-formation epoch, operate on the internal stellar population of a significant fraction of cluster galaxies. In addition, the mean age of the oldest galaxies in a cluster are correlated with cluster velocity dispersion implying that galaxy formation in massive clusters begins at earlier epochs than less massive clusters.Comment: 35 pages, 10 figures, accepted by Ap

The x ray reflectivity of the AXAF VETA-I optics

The x-ray reflectivity of the VETA-I optic, the outermost shell of the AXAF x-ray telescope, with a bare Zerodur surface, is measured and compared with theoretical predictions. Measurements made at energies of 0.28, 0.9, 1.5, 2.1, and 2.3 keV are compared with predictions based on ray trace calculations. The data were obtained at the x-ray calibrations facility at Marshall Space Flight Center with an electron impact x-ray source located 528 m from the grazing incidence mirror. The source used photoelectric absorption filters to eliminate bremsstrahlung continuum. The mirror has a diameter of 1.2 m and a focal length of 10 m. The incident and reflected x-ray flux are detected using two proportional counters, one located in the incident beam of x-rays at the entrance aperture of the VETA-I, and the other in the focal plane behind an aperture of variable size. Results on the variation of the reflectivity with energy as well as the absolute value of the reflectivity are presented. We also present a synchrotron reflectivity measurement with high energy resolution over the range 0.26 to 1.8 keV on a flat Zerodur sample, done at NSLS. We present evidence for contamination of the flat by a thin layer of carbon on the surface, and the possibility of alteration of the surface composition of the VETA-I mirror perhaps by the polishing technique. The overall agreement between the measured and calculated effective area of VETA-I is between 2.6 percent and 10 percent, depending on which model for the surface composition is adopted. Measurements at individual energies deviate from the best-fitting calculation to 0.3 to 0.8 percent, averaging 0.6 percent at energies below the high energy cutoff of the mirror reflectivity, and are as high as 20.7 percent at the cutoff. We also discuss the approach to the final preflight calibration of the full AXAF flight mirror

Engaging Students In STEM Education

ABSTRACT: With the "flattening" of the global economy in the 21st century, the teaching of Science, Technology, Engineering, and Mathematics (STEM) has taken on new importance as economic competition has become truly global. STEM education has evolved into a meta-discipline, an integrated effort that removes the traditional barriers between these subjects, and instead focuses on innovation and the applied process of designing solutions to complex contextual problems using current tools and technologies. Engaging students in high quality STEM education requires programs to include rigorous curriculum, instruction, and assessment, integrate technology and engineering into the science and mathematics curriculum, and also promote scientific inquiry and the engineering design process. All students must be a part of the STEM vision, and all teachers must be provided with the proper professional development opportunities preparing them to guide all their students toward acquiring STEM literacy. By focusing on student engagement, educators from institutions of higher education and K-12 schools can work together to develop pedagogical models that provide rigorous, well-rounded education and outstanding STEM instruction. This paper defines the necessary attributes of STEM programs designed to engage all students, describes a number of model programs focused on student engagement, and discusses assessments in progress

The Prospects for X-ray Polarimetry and its Potential use for Understanding Neutron Stars

We review the state of the art for measuring the X-ray polarization of neutron stars. We discuss how valuable precision measurements of the degree and position angle of polarization as a function of energy and, where relevant, of pulse phase, would provide deeper insight into the details of the emission mechanisms. We then review the current state of instrumentation and its potential for obtaining relevant data. Finally, we conclude our discussion with some opinions as to future directions