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At least 1,351 records · Page 75

Single-distance nano-holotomography with coded apertures

High-resolution phase-contrast 3D imaging using nano-holotomography typically requires collecting multiple tomograms at varying sample-to-detector distances, usually 3 to 4. This multi-distance approach limits temporal resolution, making it impractical for operando studies. Moreover, shifting the sample complicates reconstruction, requiring precise alignment, registration, and interpolation to correct for shift-dependent magnification on the detector. In response, we propose and validate through simulations a novel, to the best of our knowledge, single-distance approach that leverages coded apertures to structure beam illumination while the sample rotates. Finally, this approach relies on a joint reconstruction scheme, which integrates phase retrieval with 3D tomography, ensuring data consistency and achieving artifact-free reconstructions from a single distance, unlocking dynamic experiments.

Nikitin, Viktor [Argonne National Laboratory (ANL)↗

A Handheld Medical Diagnostic Device for Harsh Environments

Medical diagnostic capabilities for extreme environments, are currently limited in nature to single marker type assays. We propose to develop a handheld device for medical diagnostics in extreme environments that provide sensitive and specific detection of biomarkers with an emphasis initially on radiation exposure. Such a device will have multiple uses, and will be easily adaptable to many applications. For example, first responders, the battlefield, in low resource settings in developing countries facing emerging disease outbreaks, and during long-duration space flights. To this end, we will develop highly adaptable microfluidic devices (cards) for profiling different biomarkers with an emphasis on those related to radiation exposure. We will leverage the previous centrifugal separator work from LLNL and Sandia National Laboratory. The radiation exposure biomarker work at LLNL will provide a biological platform for demonstrating the utility of the device. We will develop a fluidic system using a pump-less mechanical method (centrifugal) to move, control, order and layer fluids in the platform. This decreases complexity, while enabling simultaneous cell separation and plasma generation for two uses: the first is differential blood cell counts and the second is biomarker assay panels. This work will be accomplished in three Aims: Aim 1) Test multiplex microfluidic cards and integrated reader. Aim 2) Demonstrate system capabilities to take and process blood samples for multi-endpoint analysis. Aim 3) Test multiplex detection based on measuring differential blood cell counts, while measuring plasma protein biomarkers. The proposed work addresses the mission research challenge of chemical and biological countermeasure in that our work aims to provide new research capabilities to respond to man-made or natural outbreaks of pandemic diseases in particular in low resource and triage environments.

60 APPLIED LIFE SCIENCES↗

Long-slit Spectroscopy of Edge-on Low Surface Brightness Galaxies

We present long-slit optical spectra of 12 edge-on low surface brightness galaxies (LSBGs) positioned along their major axes. After performing reddening corrections for the emission-line fluxes measured from the extracted integrated spectra, we measured the gas-phase metallicities of our LSBG sample using both the [N ii]/H α and the R {sub 23} diagnostics. Both sets of oxygen abundances show good agreement with each other, giving a median value of 12 + log(O/H) = 8.26 dex. In the luminosity–metallicity plot, our LSBG sample is consistent with the behavior of normal galaxies. In the mass–metallicity diagram, our LSBG sample has lower metallicities for lower stellar mass, similar to normal galaxies. The stellar masses estimated from z -band luminosities are comparable to those of prominent spirals. In a plot of the gas mass fraction versus metallicity, our LSBG sample generally agrees with other samples in the high gas mass fraction space. Additionally, we have studied stellar populations of three LSBGs, which have relatively reliable spectral continua and high signal-to-noise ratios, and qualitatively conclude that they have a potential dearth of stars with ages <1 Gyr instead of being dominated by stellar populations with ages >1 Gyr. Regarding the chemical evolution of our sample, the LSBG data appear to allow for up to 30% metal loss, but we cannot completely rule out the closed-box model. Additionally, we find evidence that our galaxies retain up to about three times as much of their metals compared with dwarfs, consistent with metal retention being related to galaxy mass. In conclusion, our data support the view that LSBGs are probably just normal disk galaxies continuously extending to the low end of surface brightness.

79 ASTRONOMY AND ASTROPHYSICS↗

The Cloud-resolving model Radar SIMulator (CR-SIM) Version 3.3: description and applications of a virtual observatory

Ground-based observatories use multi-sensor observations to characterize cloud and precipitation properties. One of the challenges is how to design strategies to best use these observations to understand these properties and evaluate weather and climate models. This paper introduces the Cloud resolving model Radar SIMulator (CR-SIM), which uses output from high-resolution cloud resolving models (CRMs) to emulate multi-wavelength, zenith-pointing, and scanning radar observables and multi-sensor (radar and lidar) products. CR-SIM allows direct comparison between an atmospheric model simulation and remote-sensing products using a forward-modeling framework consistent with the microphysical assumptions used in the atmospheric model. CR-SIM has the flexibility to easily incorporate additional microphysical modules, such as microphysical schemes and scattering calculations, and expand the applications to simulate multi-sensor retrieval products. In this paper, we present several applications of CR-SIM for evaluating the representativeness of cloud microphysics and dynamics in a CRM, quantifying uncertainties in radar-lidar integrated cloud products and multi-Doppler wind retrievals, and optimizing radar sampling strategy using observing system simulation experiments. These applications demonstrate the application of CR-SIM as a virtual observatory operator on high-resolution model output for a consistent comparison between model results and observations to aid interpretation of the differences and improve understanding of the representativeness errors due to the sampling limitations of the ground-based measurements. CR-SIM is licensed under the GNU GPL package and both the software and the user guide are publicly available to the scientific community.

54 ENVIRONMENTAL SCIENCES↗

Waste Management System overview for future spacecraft.

Waste Management Systems (WMS) for post Apollo spacecraft will be significantly more sophisticated and earthlike in user procedures. Some of the features of the advanced WMS will be accommodation of both males and females, automatic operation, either tissue wipe or anal wash, measurement and sampling of urine, feces and vomitus for medical analysis, water recovery, and solids disposal. This paper presents an overview of the major problems of and approaches to waste management for future spacecraft. Some of the processes discussed are liquid/gas separation, the Dry-John, the Hydro-John, automated sampling, vapor compression distillation, vacuum distillation-catalytic oxidation, incineration, and the integration of the above into complete systems.

Ingelfinger, A. L.↗

Study of ephemeris accuracy of the minor planets

The current state of minor planet ephemerides was assessed, and the means for providing and updating these emphemerides for use by both the mission planner and the astronomer were developed. A system of obtaining data for all the numbered minor planets was planned, and computer programs for its initial mechanization were developed. The computer based system furnishes the osculating elements for all of the numbered minor planets at an adopted date of October 10, 1972, and at every 400 day interval over the years of interest. It also furnishes the perturbations in the rectangular coordinates relative to the osculating elements at every 4 day interval. Another computer program was designed and developed to integrate the perturbed motion of a group of 50 minor planets simultaneously. Sampled data resulting from the operation of the computer based systems are presented.

Brooks, D. R.↗

The helium 10830 A line in early-type stars - An atlas of Fabry-Perot scans

Representative profiles of He I 10830 A in 65 early-type (O6-A1) stars over a wide range of luminosity are presented. The atlas scans were obtained using the Vaughan Fabry-Perot interferometer on the C. E. K. Mees 0.6 m and KPNO 0.9 m telescopes and usually cover a range of plus or minus 15 A at 1 A resolution with sampling distances between 0.5 A and 2 A depending on the photometer integration time required to reach reasonable Poisson counting statistics. The majority of the scans show very shallow, broad features which do not agree with plane-parallel NLTE model atmosphere calculations of the 10830 line by Auer and Mihalas (1972). Difficulties connected with previous theoretical studies of this line are briefly discussed, and suggestions for possible future modifications to the theory are made.

Meisel, D. D.↗

On the search for trajectories for a cometary nucleus sample return mission

The steps in the procedure for the generation of single trajectories for a comet nucleus sample return mission described by Stuhlinger et al. (1985) are discussed. The following assumptions are made for such a mission: (1) the spacecraft is equipped with an ion propulsion system supplied by solar cells, and (2) the comet has a low inclination and a period of about six years. The calculation of a specific trajectory incorporates the following main parameters: (1) the spacecraft mass at the beginning of the mission and the hyperbolic excess velocity, (2) the mass as a function of the injection energy, and (3) the available thrust level. The limitation of a supply of solar electric power to the region within 3 AU of the sun and the placement of permanent in-situ experiments at the comet are discussed. It is concluded that single trajectories for a nucleus sample return mission can be generated. A further step would be an integration of single solutions into classes of trajectories.

Schobert, D.↗

SIRTF nod maneuvers

The response of the Space Infrared Telescope Facility's attitude control system to a nod command is studied under a wide variety of conditions. Several engineering issues are explored: the effects of variations in the structural model, relocation of sensors and actuators, the influence of the fine guidance sensor sampling period, resolution and noise on the system response, torque and rate integrating gyro noise and disturbances. Simulation results using control moment gyros and reaction wheels as actuators are presented.

Rajan, N.↗

Mast material test program (MAMATEP)

The MAMATEP program, which is aimed at verifying the need for and evaluating the performance of various protection techniques for the solar array assembly mast of the Space Station photovoltaic power module, is discussed. Coated and uncoated mast material samples have been environmentally tested and evaluated, before and after testing, in terms of mass and bending modulus. The protective coatings include CV-1144 silicone, a Ni/Al/InSn eutectic, and an open-weave Al braid. Long-term plasma asher results from unprotected samples indicate that, even though fiberglass-epoxy samples degrade, a protection technique may not be necessary to ensure structural integrity. A protection technique, however, may be desirable to limit or contain the amount of debris generated by the degradation of the fiberglass-epoxy.

Ciancone, Michael L.↗

A 1.49 GHz atlas of the IRAS Bright Galaxy Sample

The VLA has been used in its A-, B-, C-, and D-configurations to make 1.49 GHz maps of sources in both the original and revised IRAS Bright Galaxy Samples of strong extragalactic sources selected at a wavelength of 60 microns. Integrated 1.49 GHz flux densities were obtained from the lowest resolution maps, and maps were made with higher resolution so that nearly all of the radio sources have been at least partially resolved. Only NGC 1377 was not detected at 1.49 GHz. An atlas of contour maps, a table of total flux densities plus other radio source parameters, and references to published radio maps are given. Since the infrared and radio continuum brightness distributions of IR-selected galaxies are usually similar, these high-resolution radio maps can be used as substitutes for the unavailable IR maps to indicate the sizes and precise locations of the IR-emitting regions.

Condon, J. J.↗

Space Station Payload Adaptation System

The development and design of a system of containers for the efficient integration of Space Station payloads is described called the Space Station Payload Adaptation System (SSPAS). The SSPAS was developed to address the incorporation of multiple payloads, the use of a small payload carrier, large numbers of samples, and on-orbit servicing. SSPAS subsystems such as the Spacelab rack are modular and designed for integration into the 'Quick Is Beautiful' (QIB) facility. The QIB is designed to provide access to space for small- and medium-sized microgravity research projects and proof-of-concept investigations. The power-distribution and heat-rejection potential of the QIB are described, and an improved experiment-apparatus container is proposed. The SSPAS rack-mounting and container concepts are concluded to make up an efficent system that can effectively exploit the R&D potential of the Space Station.

Taylor, Kenneth R.↗

Integrated multidisciplinary analysis of segmented reflector telescopes

The present multidisciplinary telescope-analysis approach, which encompasses thermal, structural, control and optical considerations, is illustrated for the case of an IR telescope in LEO; attention is given to end-to-end evaluations of the effects of mechanical disturbances and thermal gradients in measures of optical performance. Both geometric ray-tracing and surface-to-surface diffraction approximations are used in the telescope's optical model. Also noted is the role played by NASA-JPL's Integrated Modeling of Advanced Optical Systems computation tool, in view of numerical samples.

Briggs, Hugh C.↗

Versatile Dual-Channel Waveform Generator

Programmable waveform generator synthesizes two independent waveforms simultaneously at frequencies up to 250 MHz. Can be in phase or out of phase with each other. Use of commercial integrated circuits helps keep cost low. Operation governed by BASIC source code enabling any user equipped with suitable personal computer to specify waveforms. User can modify source code to satisfy special needs. Other applications include simulation of Doppler waveforms for radar, and of video signals for testing color displays and computer monitors. With eventual substitution of gallium arsenide integrated circuits for its present silicon integrated circuits, instrument able to generate waveforms with 14-bit precision and sample rates as high as 2 GHz.

Staples, Edward J.↗

HO2 detection by near infrared absorption using tunable diode lasers

The strongest absorption lines are in the v sub 2 vibrational band around 1400/cm; several near-coincident line pairs in this region provide max linestrengths of 1.2 x 10 exp -20 sq. cm/(molecule*cm). High Frequency wavelength modulation coupled with sweep integration were used to minimize noise and maintain spectral discrimination. Reduced pressure sampling was performed using supersonic nozzle and an aerodynamic flow cell to minimize residence time and wall losses of radicals. The astigmatic mirror design provides pathlengths up to 200 m in volume of 3 liters with minimal optical interference fringes; longer pathlengths are possible. The detection limit depends on pathlength and minimum fractional absorptions.

Nelson, David↗

Performance of a Ka-band transponder breadboard for deep-space applications

This article summarizes the design concepts applied in the development of and advanced Ka-band (34.4 GHz/32 GHz) transponder breadboard for the next generation of space communications systems applications. The selected architecture upgrades the X-band (7.2 GHz/8.4 GHz) deep-space transponder (DST) to provide Da-band up/Ka- and X-band down capability. The Ka-band transponder breadboard incorporates several state-of-the-art components, including sampling mixers, a Ka-band dielectric resonator oscillator, and microwave monolithic integrated circuits (MMICs). The MMICs that were tested in the breadboard include upconverters, downconverters, automatic gain control circuits, mixers, phase modulators, and amplifiers. The measured receiver dynamic range, tracking range, acquisition rate, static phase error, and phase jitter characteristics of the Ka-band breadboard interfaced to the advanced engineering model X-band DST are in good agreement with the expected performance. The results show a receiver tracking threshold of -149 dBm with a dynamic range of 80 dB and a downlink phase jitter of 7 deg rms. The analytical results of phase noise and Allan standard deviation are in good agreement with the experimental results.

Mysoor, N. R.↗

Noble Gas Analysis for Mars Robotic Missions: Evaluating K-Ar Age Dating for Mars Rock Analogs and Martian Shergottites

The purpose of this noble gas investigation was to evaluate the possibility of measuring noble gases in martian rocks and air by future robotic missions such as the Mars Science Laboratory (MSL). The MSL mission has, as part of its payload, the Sample Analysis at Mars (SAM) instrument, which consists of a pyrolysis oven integrated with a GCMS. The MSL SAM instrument has the capability to measure noble gas compositions of martian rocks and atmosphere. Here we suggest the possibility of K-Ar age dating based on noble gas release of martian rocks by conducting laboratory simulation experiments on terrestrial basalts and martian meteorites. We provide requirements for the SAM instrument to obtain adequate noble gas abundances and compositions within the current SAM instrumental operating conditions, especially, a power limit that prevents heating the furnace above approx.1100 C. In addition, Martian meteorite analyses from NASA-JSC will be used as ground truth to evaluate the feasibility of robotic experiments to constrain the ages of martian surface rocks.

Park, J.↗

Miniature Bioreactor System for Long-Term Cell Culture

A prototype miniature bioreactor system is designed to serve as a laboratory benchtop cell-culturing system that minimizes the need for relatively expensive equipment and reagents and can be operated under computer control, thereby reducing the time and effort required of human investigators and reducing uncertainty in results. The system includes a bioreactor, a fluid-handling subsystem, a chamber wherein the bioreactor is maintained in a controlled atmosphere at a controlled temperature, and associated control subsystems. The system can be used to culture both anchorage-dependent and suspension cells, which can be either prokaryotic or eukaryotic. Cells can be cultured for extended periods of time in this system, and samples of cells can be extracted and analyzed at specified intervals. By integrating this system with one or more microanalytical instrument(s), one can construct a complete automated analytical system that can be tailored to perform one or more of a large variety of assays.

Gonda, Steve R.↗