Four Bed Molecular Sieve - Exploration (4BMS-X) Virtual Heater Design and Optimization

A 4BMS-X (Four Bed Molecular Sieve - Exploration) design and heater optimization study for CO2 sorbent beds in proposed exploration system architectures is presented. The primary objectives of the study are to reduce heater power and thermal gradients within the CO2 sorbent beds while minimizing channeling effects. Some of the notable changes from the ISS (International Space Station) CDRA (Carbon Dioxide Removal Assembly) to the proposed exploration system architecture include cylindrical beds, alternate sorbents and an improved heater core. Results from both 2D and 3D sorbent bed thermal models with integrated heaters are presented. The 2D sorbent bed models are used to optimize heater power and fin geometry while the 3D models address end effects in the beds for more realistic thermal gradient and heater power predictions

Anomalous \u3ci\u3eF\u3c/i\u3e Region Response to Moderate Solar Flares

Ionograms recorded with a dynasonde at Bear Lake Observatory, Utah, during moderate solar x-ray flares exhibit characteristic enhancements to the E and F 1 region ionosphere. However, during these same flares, the peak electron density of the ionosphere (N m F 2) unexpectedly decreases, recovering after the flare ends. In order to reconcile this anomalous behavior with expected increases to the total electron content (TEC), we undertake a modeling effort using the Time-Dependent Ionospheric Model (TDIM) developed at Utah State University. For solar input, a simple flare time irradiance model is created, using measurements from the Solar EUV Experiment instrument on the TIMED spacecraft. TDIM simulations show that the anomalous N m F 2 response can be explained by assuming a rapid electron temperature increase, which increases the O+ scale height, moving plasma to higher altitudes. The model results are able to reproduce both the decreasing N m F 2 as well as the expected TEC enhancement

The flow of plasma in the solar terrestrial environment

The overall goal of our NASA Theory Program was to study the coupling, time delays, and feedback mechanisms between the various regions of the solar-terrestrial system in a self-consistent, quantitative manner. To accomplish this goal, it will eventually be necessary to have time-dependent macroscopic models of the different regions of the solar-terrestrial system and we are continually working toward this goal. However, with the funding from this NASA program, we concentrated on the near-earth plasma environment, including the ionosphere, the plasmasphere, and the polar wind. In this area, we developed unique global models that allowed us to study the coupling between the different regions. These results are highlighted in the next section. Another important aspect of our NASA Theory Program concerned the effect that localized 'structure' had on the macroscopic flow in the ionosphere, plasmasphere, thermosphere, and polar wind. The localized structure can be created by structured magnetospheric inputs (i.e., structured plasma convection, particle precipitation or Birkland current patterns) or time variations in these input due to storms and substorms. Also, some of the plasma flows that we predicted with our macroscopic models could be unstable, and another one of our goals was to examine the stability of our predicted flows. Because time-dependent, three-dimensional numerical models of the solar-terrestrial environment generally require extensive computer resources, they are usually based on relatively simple mathematical formulations (i.e., simple MHD or hydrodynamic formulations). Therefore, another goal of our NASA Theory Program was to study the conditions under which various mathematical formulations can be applied to specific solar-terrestrial regions. This could involve a detailed comparison of kinetic, semi-kinetic, and hydrodynamic predictions for a given polar wind scenario or it could involve the comparison of a small-scale particle-in-cell (PIC) simulation of a plasma expansion event with a similar macroscopic expansion event. The different mathematical formulations have different strengths and weaknesses and a careful comparison of model predictions for similar geophysical situations provides insight into when the various models can be used with confidence

Bounds on the basic physical parameters for anisotropic compact general relativistic objects

We derive upper and lower limits for the basic physical parameters (mass-radius ratio, anisotropy, redshift and total energy) for arbitrary anisotropic general relativistic matter distributions in the presence of a cosmological constant. The values of these quantities are strongly dependent on the value of the anisotropy parameter (the difference between the tangential and radial pressure) at the surface of the star. In the presence of the cosmological constant, a minimum mass configuration with given anisotropy does exist. Anisotropic compact stellar type objects can be much more compact than the isotropic ones, and their radii may be close to their corresponding Schwarzschild radii. Upper bounds for the anisotropy parameter are also obtained from the analysis of the curvature invariants. General restrictions for the redshift and the total energy (including the gravitational contribution) for anisotropic stars are obtained in terms of the anisotropy parameter. Values of the surface redshift parameter greater than two could be the main observational signature for anisotropic stellar type objects.Comment: 18 pages, no figures, accepted for publication in CQ

What is the Source of Observed Annual Variations in Plasmaspheric Density?

Plasmaspheric densities have been observed previously to be higher in December than in June, with the ratio varying between 1.5 and 3.0 and with larger variations at lower L shells. In order to search for the cause of the observed annual variations, we have modeled plasmaspheric density, using a time-dependent hydrodynamic model. On an L = 2 field line with geomagnetic longitude equal to 300°, the modeled plasmaspheric densities were a factor of 1.5 times higher in December than in June. The modeled December to June density ratio was found to increase slightly with L shell, in contrast to observations; this discrepancy may be due to the fact that outer plasmaspheric flux tubes are never completely full. In addition, for an L = 2 field line with geomagnetic longitude equal to 120°, the modeled plasmaspheric density was higher in June than in December by a factor of about 1.2. Various numerical tests were also performed in order to examine the sensitivity of plasmaspheric density to various parameters. In particular, a large vertical neutral wind was applied in order to raise the O+ profile, which had the effect of raising plasmaspheric density by a factor of 6. This in conjunction with a theoretical analysis suggests that plasmaspheric density levels are very sensitive to O+ levels in the upper ionosphere. We conclude that annual variations in plasmaspheric density are due to similar variations in ionospheric O+

Modeling solar zenith angle effects on the polar wind

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95680/1/jgra21673.pd

Electrophysiological characterization of activation state-dependent Cav2 channel antagonist TROX-1 in spinal nerve injured rats

AbstractPrialt, a synthetic version of Cav2.2 antagonist ω-conotoxin MVIIA derived from Conus magus, is the first clinically approved voltage-gated calcium channel blocker for refractory chronic pain. However, due to the narrow therapeutic window and considerable side effects associated with systemic dosing, Prialt is only administered intrathecally. N-triazole oxindole (TROX-1) is a novel use-dependent and activation state-selective small-molecule inhibitor of Cav2.1, 2.2 and 2.3 calcium channels designed to overcome the limitations of Prialt. We have examined the neurophysiological and behavioral effects of blocking calcium channels with TROX-1. In vitro, TROX-1, in contrast to state-independent antagonist Prialt, preferentially inhibits Cav2.2 currents in rat dorsal root ganglia (DRG) neurons under depolarized conditions. In vivo electrophysiology was performed to record from deep dorsal horn lamina V/VI wide dynamic range neurons in non-sentient spinal nerve-ligated (SNL) and sham-operated rats. In SNL rats, spinal neurons exhibited reduced responses to innocuous and noxious punctate mechanical stimulation of the receptive field following subcutaneous administration of TROX-1, an effect that was absent in sham-operated animals. No effect was observed on neuronal responses evoked by dynamic brushing, heat or cold stimulation in SNL or sham rats. The wind-up response of spinal neurons following repeated electrical stimulation of the receptive field was also unaffected. Spinally applied TROX-1 dose dependently inhibited mechanically evoked neuronal responses in SNL but not sham-operated rats, consistent with behavioral observations. This study confirms the pathological state-dependent actions of TROX-1 through a likely spinal mechanism and reveals a modality selective change in calcium channel function following nerve injury

Academic achievement : the role of praise in motivating students

The motivation of students is an important issue in higher education, particularly in the context of the increasing diversity of student populations. A social-cognitive perspective assumes motivation to be dynamic, context-sensitive and changeable, thereby rendering it to be a much more differentiated construct than previously understood. This complexity may be perplexing to tutors who are keen to develop applications to improve academic achievement. One application that is within the control of the tutor, at least to some extent, is the use of praise. Using psychological literature the article argues that in motivating students, the tutor is not well served by relying on simplistic and common sense understandings of the construct of praise and that effective applications of praise are mediated by students' goal orientations, which of themselves may be either additive or interactive composites of different objectives and different contexts

The role of self-efficacy as an attribute of principals’ leadership effectiveness in K-12 private and public institutions in Lebanon

© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. The aim of this study is to explore the role of K-12 school principals’ self-efficacy as an attribute for their leadership effectiveness in Lebanon. The Norwegian principal self-efficacy scale (NPSES) instrument was translated into Arabic and used to collect quantitative data from participants. Internal consistency of factors within this study was checked (24 items; α = 0.73). By comparing private and public schools in Lebanon, all located in the governorate of Mount Lebanon, the researchers revealed the extent to which principals’ self-efficacy plays a role in their leadership. In addition, while no statistical difference was found between self-efficacy levels of private and public principals, females reported higher scores on the majority of the dimensions than their male counterparts in both types of schools. This study highlights the importance of the interaction effect of age and gender on self-efficacy levels. Moreover, it offers knowledge and practice to policy makers when recruiting principals or designing training programs. It also suggests the implementation of an in-house mentoring program to create school-school partnerships. Finally, this paper offers a platform for future researchers interested in principal self-efficacy in similar conflict-affected places with high economic depression. Limitations are further mentioned

A Finite Element Method for Free-Surface Flows of Incompressible Fluids in Three Dimensions, Part II: Dynamic Wetting Lines

To date, few researchers have solved three-dimensional free-surface problems with dynamic wetting lines. This paper extends the free-surface finite element method described in a companion paper [Cairncross, R.A., P.R. Schunk, T.A. Baer, P.A. Sackinger, R.R. Rao, "A finite element method for free surface flows of incompressible fluid in three dimensions, Part I: Boundary-Fitted mesh motion.", to be published (1998)] to handle dynamic wetting. A generalization of the technique used in two dimensional modeling to circumvent double-valued velocities at the wetting line, the so-called kinematic paradox, is presented for a wetting line in three dimensions. This approach requires the fluid velocity normal to the contact line to be zero, the fluid velocity tangent to the contact line to be equal to the tangential component of web velocity, and the fluid velocity into the web to be zero. In addition, slip is allowed in a narrow strip along the substrate surface near the dynamic contact line. For realistic wetting-line motion, a contact angle which varies with wetting speed is required because contact lines in three dimensions typically advance or recede a different rates depending upon location and/or have both advancing and receding portions. The theory is applied to capillary rise of static fluid in a corner, the initial motion of a Newtonian droplet down an inclined plane, and extrusion of a Newtonian fluid from a nozzle onto a moving substrate. The extrusion results are compared to experimental visualization. Subject Categorie