Carbonyl-functionalized thiophene compounds and related device structures
Carbonyl-functionalized oligo/polythiophene compounds, and related semiconductor components and related device structures.
Marks, Tobin J.↗
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Carbonyl-functionalized thiophene compounds and related device structures
Carbonyl-functionalized oligo/polythiophene compounds, and related semiconductor components and related device structures.
Marks, Tobin J.↗
The Use of Structural-Acoustic Techniques to Assess Potential Structural Damage From Sonic Booms
The potential impact of supersonic operations includes structural damage from the sonic boom overpressure. This paper describes a study of how structural-acoustic modeling and testing techniques may be used to assess the potential for such damage in the absence of actual flyovers. Procedures are described whereby transfer functions relating structural response to sonic boom signature may be obtained with a stationary acoustic source and appropriate data processing. Further, by invoking structural-acoustic reciprocity, these transfer functions may also be acquired by measuring the radiated sound from the structure under a mechanical drive. The approach is based on the fundamental assumption of linearity, both with regard to the (acoustic) propagation of the boom in the vicinity of the structure and to the structure's response. Practical issues revolve around acoustic far field and source directivity requirements. The technique was implemented on a specially fabricated test structure at Edwards AFB, CA with the support of Wyle Laboratories, Inc. Blank shots from a cannon served as our acoustic source and taps from an instrumented hammer generated the mechanical drive. Simulated response functions were constructed. Results of comparisons with corresponding measurements recorded during dedicated supersonic flyovers with F-15 aircraft are presented for a number of sensor placements.
Garrelick, Joel↗
In Vivo Dieletric Response as Related to Tissue Structure, Function and Physiologic Activity in Selected Trees
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vegetated terrain Physiologic Activity Vivo Dielet↗
Long Duration Head Down Tilt Bed Rest and Spaceflight Effects on Neurocognitive Performance: Extent, Longevity and Neural Bases
We have recently completed a long duration head down tilt bed rest (HDBR) study in which we performed structural and functional magnetic resonance brain imaging to identify the relationships between changes in neurocognitive function and neural structural alterations in a spaceflight analog environment. We are also collecting the same measures in crewmembers prior to and following a six month International Space Station mission. We will present data demonstrating that bed rest resulted in functional mobility and balance deterioration with recovery post-HDBR. We observed numerous changes in brain structure, function, and connectivity relative to a control group which were associated with pre to post bed rest changes in sensorimotor function. For example, gray matter volume (GMv) increased in posterior parietal areas and decreased in frontal regions. GMv increases largely overlapped with fluid decreases and vice versa. Larger increases in precentral gyrus (M1)/ postcentral gyrus (S1+2) GMv and fluid decreases were associated with smaller balance decrements. Vestibular activation in the bilateral insular cortex increased with bed rest and subsequently recovered. Larger increases in vestibular activation in multiple brain regions were associated with greater decrements in balance and mobility. We found connectivity increases between left M1 with right S1+2 and the superior parietal lobule, and right vestibular cortex with the cerebellum. Decreases were observed between right Lobule VIII with right S1+2 and the supramarginal gyrus, right posterior parietal cortex (PPC) with occipital regions, and the right superior posterior fissure with right Crus I and II. Connectivity strength between left M1 and right S1+2/superior parietal lobule increased the most in individuals that exhibited the least balance impairments. In sum, we observed HDBR-related changes in measures of brain structure, function, and network connectivity, which correlated with indices of sensorimotor function. Recovery was observed post HDBR but remained incomplete at 12 days post-HDBR. Preliminary findings from our parallel ongoing flight study will be compared and contrasted with bed rest results during this presentation.
Seidler, R. D.↗
Design of long-endurance unmanned airplanes incorporating solar and fuel cell propulsion
Attention is given to the design features and operational capabilities of a class of unmanned flight vehicles possessing multiday mission endurance capabilities, based on the use of a mixed-mode electric power system which incorporates solar cells for diurnal energy production and a nonregenerative H2-O2 fuel cell for nocturnal energy supply. Energy is thereby provided for not only propulsion, but also the operation of the payload and the vehicle's avionics. The excess solar energy available during high insolation portions of the diurnal period may be used for climb/maneuvering or payload-related functions. Empirical structure scaling algorithms are combined with low Reynolds number aerodynamics algorithms to estimate requisite size and geometry for the chosen mission. Wing loadings will be of the order of 0.9-1.3 lb/sq ft.
Youngblood, J. W.↗
Focal Gray Matter Plasticity as a Function of Long Duration Head-down Tilt Bed Rest
Long duration spaceflight (i.e., > or = 22 days) has been associated with changes in sensorimotor systems, resulting in difficulties that astronauts experience with posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes. Whether these sensorimotor changes may be related to structural and functional brain changes is yet unknown. However, experimental studies revealed changes in the gray matter (GM) of the brain after simulated microgravity. Thus, it is possible that spaceflight may affect brain structure and thereby cognitive functioning and motor behavior. Long duration head-down tilt bed rest has been suggested as an exclusionary analog to study microgravity effects on the sensorimotor system. Bed rest mimics microgravity in body unloading and bodily fluid shifts. In consideration of the health and performance of crewmembers both in- and post-flight, we are conducting a prospective longitudinal 70-day bed rest study as an analog to investigate the effects of microgravity on the brain. VBM analysis revealed a progressive decrease from pre- to in- bed rest in GM volume in bilateral areas including the frontal medial cortex, the insular cortex and the caudate. Over the same time period, there was a progressive increase in GM volume in the cerebellum, occipital-, and parietal cortex, including the precuneus. The majority of these changes did not fully recover during the post-bed rest period. Analysis of lobular GM volumes obtained with BRAINS showed significantly increased volume from pre-bed rest to in-bed rest in GM of the parietal lobe and the third ventricle. Temporal GM volume at 70 days in bed rest was smaller than that at the first pre-bed rest measurement. Trend analysis showed significant positive linear and negative quadratic relationships between parietal GM and time, a positive linear relationship between third ventricle volume and time, and a negative linear relationship between cerebellar GM volume and time. FM performance improved from pre-bed rest session 1 to session 2. From the second pre-bed rest measure to the last-day-in-bed rest, there was a significant decrease in performance that only partially recovered post-bed rest. No significant association was observed between changes in brain volume and changes in functional mobility. Extended bed rest, which is an analog for microgravity, can result in local volumetric GM increase and decrease and adversely affect functional mobility. These changes in brain structure and performance were not related in this sample. Whether the effects of bed rest dissipate at longer times post-bed rest, and if they are associated with behavior are important questions that warrant further research including more subjects and longer follow-up times.
Koppelmans, V.↗
Focal Gray Matter Plasticity as a Function of Long Duration Head-down Tilt Bed Rest
Long duration spaceflight (i.e., 22 days or longer) has been associated with changes in sensorimotor systems, resulting in difficulties that astronauts experience with posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes. Whether these sensorimotor changes may be related to structural and functional brain changes is yet unknown. However, increased intracranial pressure that by itself has been related to microgravity-induced bodily fluid shifts: [1] has been associated with white matter microstructural damage, [2] Thus, it is possible that spaceflight may affect brain structure and thereby cognitive functioning. Long duration head-down tilt bed rest has been suggested as an exclusionary analog to study microgravity effects on the sensorimotor system, [3] Bed rest mimics microgravity in body unloading and bodily fluid shifts. In consideration of the health and performance of crewmembers both in- and post-flight, we are conducting a prospective longitudinal 70-day bed rest study as an analog to investigate the effects of microgravity on brain structure, and [4] Here we present results of the first eight subjects.
Koppelmans, Vincent↗
Focal Gray Matter Plasticity as a Function of Long Duration Head Down Tilted Bed Rest: Preliminary Results
Long duration spaceflight (i.e., 22 days or longer) has been associated with changes in sensorimotor systems, resulting in difficulties that astronauts experience with posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes. Whether these sensorimotor changes are solely related to peripheral changes from reduced vestibular stimulation, body unloading, body fluid shifts or that they may be related to structural and functional brain changes is yet unknown. However, a recent study reported associations between microgravity and flattening of the posterior eye globe and protrusion of the optic nerve [1] possibly as the result of increased intracranial pressure due to microgravity induced bodily fluid shifts [3]. Moreover, elevated intracranial pressure has been related to white matter microstructural damage [2]. Thus, it is possible that spaceflight may affect brain structure and thereby cognitive functioning. Long duration head down tilt bed rest has been suggested as an exclusionary analog to study microgravity effects on the sensorimotor system [4]. Bed rest mimics microgravity in body unloading and bodily fluid shifts. In consideration of the health and performance of crewmembers both in- and post-flight, we are conducting a prospective longitudinal 70-day bed rest study as an analog to investigate the effects of microgravity on brain structure [5]. Here we present results of the first six subjects. Six subjects were assessed at 12 and 7 days before-, at 7, 30, and ~70 days in-, and at 8 and 12 days post 70 days of bed rest at the NASA bed rest facility in UTMB, Galveston, TX, USA. At each time point structural MRI scans (i.e., high resolution T1-weighted imaging and Diffusion Tensor Imaging (DTI)) were obtained using a 3T Siemens scanner. Focal changes over time in gray matter density were assessed using the voxel based morphometry 8 (VBM8) toolbox under SPM. Longitudinal processing in VBM8 includes linear registration of each scan to the mean of the subject and subsequently transforming all scans in to MNI space by applying the warp from the mean subject to MNI to the individual gray matter segmentations. Modulation was applied so that all images represented the volume of the original structure in native space. Voxel wise analysis was carried out on the gray matter images after smoothing, using a flexible factorial design with family wise error correction. Focal changes in white matter microstructural integrity were assessed using tract based spatial statistics (TBSS) as part of FMRIB software library (FSL). TBSS registers all DTI scans to standard space. It subsequently creates a study specific white matter skeleton of the major white matter tracts. For each subject, for each DTI metric (i.e. fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD)), the maximum value in a line perpendicular to the skeleton tract is projected to the skeleton. Non-parametric permutation based t-tests and ANOVA's were used for voxel-wise comparison of the skeletons. For both VBM and TBSS, comparison of pre bed rest measurements did not show significant differences. VBM analysis revealed decreased gray matter density in bilateral areas including the frontal medial cortex, the insular cortex and the caudate (see Figure) from 'pre to in bed rest'. Over the same time period, there was an increase in gray matter density in the cerebellum, occipital-, and parietal cortex, including the precuneus (see Figure). The majority of these changes did not recover from 'during to post bed rest'. TBSS analysis did not reveal significant changes in white matter microstructural integrity after correction for multiple comparisons. Uncorrected analyses (p<.015) revealed an increase in RD in the cerebellum and brainstem from pre bed rest to the first week in bed rest that did not recover post bed rest. Extended bed rest, which is an analog for microgravity, can result in gray matter changes and potentially in microstructural white matter changes in areas that are important for neuro motor behavior and cognition. These changes did not recover at two weeks post bed rest. Whether the effects of bed rest wear off at longer times post bed rest, and if they are associated with behavior are important questions that warrant further research.
Koppelmans, V.↗
DNA in a Tunnel: A Comfy Spot for Recognition - or -The Structure of BsoBI Complexed with DNA. What can we Learn about Function via Structure Determination and how can this be Applied to Bone or Muscle Biology?
The structure and function of a biologically active molecule are related. To understand its function, it is necessary (but not always sufficient) to know the structure of the molecule. There are many ways of relating the molecular function with the structure. Mutation analysis can identify pertinent amino acids of an enzyme, or alternatively structure comparison of the of two similar molecules with different function may lead to understanding which parts are responsible for a functional aspect, or a series of "structural cartoons" - enzyme structure, enzyme plus substrate, enzyme with transition state analog, and enzyme with product - may give insight in the function of a molecule. As an example we will discuss the structure and function of the restriction enzyme BsoBI from Bacillus stearothemzophilus in complex with its cognate DNA. The enzyme forms a unique complex with DNA in that it completely encircles the DNA. The structure reveals the enzyme-DNA contacts, how the DNA is distorted compared with the canonical forms, and elegantly shows how two distinct DNA sequences can be recognized with the same efficiency. Based on the structure we may also propose a hypothesis how the enzymatic mechanism works. The knowledge gained thru studies such as this one can be used to alter the function by changing the molecular structure. Usually this is done by design of inhibitors specifically active against and fitting into an active site of the enzyme of choice. In the case of BsoBI one of the objectives of the study was to alter the enzyme specificity. In bone biology there are many candidates available for molecular study in order to explain, alter, or (temporarily) suspend activity. For example, the understanding of a pathway that negatively regulates bone formation may be a good target for drug design to stimulate bone formation and have good potential as the basis for new countermeasures against bone loss. In principle the same approach may aid muscle atrophy, radiation damage, immune response changes and other risks identified for long-duration Space travel.
vanderWoerd, Mark↗
Dynamical interpretation of conditional patterns
While great progress is being made in characterizing the 3-D structure of organized turbulent motions using conditional averaging analysis, there is a lack of theoretical guidance regarding the interpretation and utilization of such information. Questions concerning the significance of the structures, their contributions to various transport properties, and their dynamics cannot be answered without recourse to appropriate dynamical governing equations. One approach which addresses some of these questions uses the conditional fields as initial conditions and calculates their evolution from the Navier-Stokes equations, yielding valuable information about stability, growth, and longevity of the mean structure. To interpret statistical aspects of the structures, a different type of theory which deals with the structures in the context of their contributions to the statistics of the flow is needed. As a first step toward this end, an effort was made to integrate the structural information from the study of organized structures with a suitable statistical theory. This is done by stochastically estimating the two-point conditional averages that appear in the equation for the one-point probability density function, and relating the structures to the conditional stresses. Salient features of the estimates are identified, and the structure of the one-point estimates in channel flow is defined.
Adrian, R. J.↗
The velocity structure and turbulence at the center of the Orion Nebula
Using the Coude Feed System of the Kitt Peak National Observatory at its highest possible dispersion and a CCD detector with wide dynamic range it was possible to examine in detail the radial and turbulent velocities of the Orion Nebula at the seeing limit. For the first time, multiple components of the spectral lines were resolved and the Gaussian profiles fit to them. Using four different observing runs, two circular areas 2 minutes in diameter were observed, the first centered on the theta sup 1 Orionis and the second centered on theta sup 2 Orionis. The velocity resolution of 1 km/s combined with the angular resolution of 2 seconds allowed observation in detail at line splitting as well as the location and measurement of high internal motions, about -50 km/s with respect to the bulk of ionized matter. Because over 900 different positions were measured, modern statistical techniques were used for the analysis of turbulence, so that the dispersion relation and the structure function could be calculated and compared with predictions of the Kolmogorov theory. The random motions showed correlation with spatial separation, as expected for turbulence; but comparison with predictions of the classical theory for nebular turbulence showed poor agreement. If Kolmogorov theory applies, then the energy must be input at many scales.
Castaneda, Hector O.↗
Leveraging Existing Mission Tools in a Re-Usable, Component-Based Software Environment
Emerging methods in component-based software development offer significant advantages but may seem incompatible with existing mission operations applications. In this paper we relate our positive experiences integrating existing mission applications into component-based tools we are delivering to three missions. In most operations environments, a number of software applications have been integrated together to form the mission operations software. In contrast, with component-based software development chunks of related functionality and data structures, referred to as components, can be individually delivered, integrated and re-used. With the advent of powerful tools for managing component-based development, complex software systems can potentially see significant benefits in ease of integration, testability and reusability from these techniques. These benefits motivate us to ask how component-based development techniques can be relevant in a mission operations environment, where there is significant investment in software tools that are not component-based and may not be written in languages for which component-based tools even exist. Trusted and complex software tools for sequencing, validation, navigation, and other vital functions cannot simply be re-written or abandoned in order to gain the advantages offered by emerging component-based software techniques. Thus some middle ground must be found. We have faced exactly this issue, and have found several solutions. Ensemble is an open platform for development, integration, and deployment of mission operations software that we are developing. Ensemble itself is an extension of an open source, component-based software development platform called Eclipse. Due to the advantages of component-based development, we have been able to vary rapidly develop mission operations tools for three surface missions by mixing and matching from a common set of mission operation components. We have also had to determine how to integrate existing mission applications for sequence development, sequence validation, and high level activity planning, and other functions into a component-based environment. For each of these, we used a somewhat different technique based upon the structure and usage of the existing application.
Greene, Kevin↗
MHD Instability and Turbulence in the Tachocline
In this quarter we have begun simulations on the Cray T3E at PSC and we are debugging our code on the TSC. The PSC simulations are examining stratified shear turbulence with a flow-aligned magnetic field and passive tracer particles. We have conducted analysis of neutral simulations to establish a firm basis of comparison. Second-order structure functions have been computed, fit, and compared to theoretical expressions relating the dissipation fields and the structure-function-fit parameters. Agreement with high-Reynolds number observations is excellent, giving us confidence that the lower-Re simulations are relevant to higher-Re flows. We have also evaluated the neutral layer anisotropy.
Werne, Joseph↗
Determination of atmospheric structure function by using a single coherent detector
The wave structure function associated with atmospheric turbulence is important in the effective design of telescopes for coherent optical receivers. This paper describes a method of measurement of the wave structure function by employing an already existing optical receiver. The aperture of this receiver's telescope is masked by an opaque screen with two small holes. It is then shown that when the incident beam obeys Gaussian statistics, the receiver's A.M. output can be simply related to the wave structure function of the incident beam.
Lang, R. H.↗
Turbulent small-scale neutral and ion density fluctuations as measured during MAC/Epsilon
During the MAC/Epsilon campaign (Fall 1987, from Andoya, Northern Norway, 69 N, 16 E) a total of four altitude profiles of neutral gas number densities and six profiles of ion number densities were measured with high spatial resolution in the height range from 60 to 120 km. First results of these rocket-borne experiments are presented with emphasis on small scale turbulent density variations and related turbulent parameter as structure function constants and energy dissipation rates.
Luebken, F.-J.↗
Industry liaison section implementation plan
The Industry Liaison Section is a new function of the Army/NASA Aircrew-Aircraft Integration (AAAI) Program that is intended to bridge an existing gap between Government developers (including contractors) and outside organizations who are potential users of products and services developed by the AAAI Program. Currently in its sixth year, the Program is experiencing considerable pull from industry and other government organizations to disseminate products. Since the AAAI Program's charter is exploratory and research in nature, and satisfying proper dissemination requirements is in conflict with the rapid prototyping approach utilized by the design team, the AAAI Program has elected to create an Industry Liaison Section (ILS) to serve as the Program's technology transfer focal point. The process by which the ILS may be established, organized and managed is described, including the baseline organizational structure, duties, functions, authority, responsibilities, relations and policies and procedures relevant to the conduct of the ILS.
Lakowske, Stephen↗
Realtime Knowledge Management (RKM): From an International Space Station (ISS) Point of View
We are developing automated methods to provide realtime access to spacecraft domain knowledge relevant a spacecraft's current operational state. The method is based upon analyzing state-transition signatures in the telemetry stream. A key insight is that documentation relevant to a specific failure mode or operational state is related to the structure and function of spacecraft systems. This means that diagnostic dependency and state models can provide a roadmap for effective documentation navigation and presentation. Diagnostic models consume the telemetry and derive a high-level state description of the spacecraft. Each potential spacecraft state description is matched against the predictions of models that were developed from information found in the pages and sections in the relevant International Space Station (ISS) documentation and reference materials. By annotating each model fragment with the domain knowledge sources from which it was derived we can develop a system that automatically selects those documents representing the domain knowledge encapsulated by the models that compute the current spacecraft state. In this manner, when the spacecraft state changes, the relevant documentation context and presentation will also change.
Robinson, Peter I.↗