Rapid and direct detection of Invivo kinetics of pathogenic bacterial infection from mouse blood and urine.

PubMed

Gopal, Judy; Lee, Chia-Hsun; Wu, Hui-Fen

2012-06-06

This study demonstrates the first use of matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) to trace the Invivo infection kinetics of the well known deadly pathogen Staphylococcus aureus in Swiss albino mice. The growth curve of the bacteria from the point of injection (200μL of bacterial suspension (10(8)cfu/mL)) into the mouse blood till mortality (death) was periodically analyzed using the plate counting method and MALDI-MS. Bacterial counts of 10(3)cfu/mL were observed in the log phase of the growth curve in the blood and 10(2)cfu/mL were observed in the urine samples. Death occurred in the log phase of the growth curve, where the bacterial counts showed steady increase. In other cases, the bacteria counts started decreasing after 48h and by 96h the bacteria got totally eliminated from the mouse and these mice survived. Direct MALDI-MS was not feasible for tracking the bacteria in the infected blood. However, ionic liquid 1-Butyl-3-methylimidazolium tetrafluoroborate was successful in enabling bacterial detection amidst the strong blood peaks. But, in the case of the urine analysis, it was observed that direct MALDI-MS was adequate to enable detection. The results obtained prove the efficacy of MALDI-MS for analyzing pathogenic bacteria in clinical samples. This article is part of a Special Issue entitled: Proteomics: The clinical link. Copyright © 2011 Elsevier B.V. All rights reserved.

High contrast observations of bright stars with a starshade

NASA Astrophysics Data System (ADS)

Harness, Anthony; Cash, Webster; Warwick, Steve

2017-11-01

Starshades are a leading technology to enable the direct detection and spectroscopic characterization of Earth-like exoplanets. In an effort to advance starshade technology through system level demonstrations, the McMath-Pierce Solar Telescope was adapted to enable the suppression of astronomical sources with a starshade. The long baselines achievable with the heliostat provide measurements of starshade performance at a flight-like Fresnel number and resolution, aspects critical to the validation of optical models. The heliostat has provided the opportunity to perform the first astronomical observations with a starshade and has made science accessible in a unique parameter space, high contrast at moderate inner working angles. On-sky images are valuable for developing the experience and tools needed to extract science results from future starshade observations. We report on high contrast observations of nearby stars provided by a starshade. We achieve 5.6 × 10- 7 contrast at 30 arcseconds inner working angle on the star Vega and provide new photometric constraints on background stars near Vega.

The CHRONOS mission: capability for sub-hourly synoptic observations of carbon monoxide and methane to quantify emissions and transport of air pollution

NASA Astrophysics Data System (ADS)

Edwards, David P.; Worden, Helen M.; Neil, Doreen; Francis, Gene; Valle, Tim; Arellano, Avelino F., Jr.

2018-02-01

The CHRONOS space mission concept provides time-resolved abundance for emissions and transport studies of the highly variable and highly uncertain air pollutants carbon monoxide and methane, with sub-hourly revisit rate at fine (˜ 4 km) horizontal spatial resolution across a North American domain. CHRONOS can provide complete synoptic air pollution maps (snapshots) of the continental domain with less than 10 min of observations. This rapid mapping enables visualization of air pollution transport simultaneously across the entire continent and enables a sentinel-like capability for monitoring evolving, or unanticipated, air pollution sources in multiple locations at the same time with high temporal resolution. CHRONOS uses a compact imaging gas filter correlation radiometer for these observations, with heritage from more than 17 years of scientific data and algorithm advances by the science teams for the Measurements of Pollution in the Troposphere (MOPITT) instrument on NASA's Terra spacecraft in low Earth orbit. To achieve continental-scale sub-hourly sampling, the CHRONOS mission would be conducted from geostationary orbit, with the instrument hosted on a communications or meteorological platform. CHRONOS observations would contribute to an integrated observing system for atmospheric composition using surface, suborbital and satellite data with atmospheric chemistry models, as defined by the Committee on Earth Observing Satellites. Addressing the U.S. National Academy's 2007 decadal survey direction to characterize diurnal changes in tropospheric composition, CHRONOS observations would find direct societal applications for air quality management and forecasting to protect public health.

Nanoscale self-templating for oxide epitaxy with large symmetry mismatch

DOE PAGES

Gao, Xiang; Lee, Shinbuhm; Nichols, John A.; ...

2016-12-02

Direct observations using scanning transmission electron microscopy unveil an intriguing interfacial bi-layer that enables epitaxial growth of a strain-free, monoclinic, bronze-phase VO 2(B) thin film on a perovskite SrTiO 3 (STO) substrate. For this study, we observe an ultrathin (2–3 unit cells) interlayer best described as highly strained VO 2(B) nanodomains combined with an extra (Ti,V)O 2 layer on the TiO 2 terminated STO (001) surface. By forming a fully coherent interface with the STO substrate and a semi-coherent interface with the strain-free epitaxial VO 2(B) film above, the interfacial bi-layer enables the epitaxial connection of the two materials despitemore » their large symmetry and lattice mismatch.« less

The FluxCompensator: Making Radiative Transfer Models of Hydrodynamical Simulations Directly Comparable to Real Observations

NASA Astrophysics Data System (ADS)

Koepferl, Christine M.; Robitaille, Thomas P.

2017-11-01

When modeling astronomical objects throughout the universe, it is important to correctly treat the limitations of the data, for instance finite resolution and sensitivity. In order to simulate these effects, and to make radiative transfer models directly comparable to real observations, we have developed an open-source Python package called the FluxCompensator that enables the post-processing of the output of 3D Monte Carlo radiative transfer codes, such as Hyperion. With the FluxCompensator, realistic synthetic observations can be generated by modeling the effects of convolution with arbitrary point-spread functions, transmission curves, finite pixel resolution, noise, and reddening. Pipelines can be applied to compute synthetic observations that simulate observatories, such as the Spitzer Space Telescope or the Herschel Space Observatory. Additionally, this tool can read in existing observations (e.g., FITS format) and use the same settings for the synthetic observations. In this paper, we describe the package as well as present examples of such synthetic observations.

The FluxCompensator: Making Radiative Transfer Models of Hydrodynamical Simulations Directly Comparable to Real Observations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koepferl, Christine M.; Robitaille, Thomas P., E-mail: koepferl@usm.lmu.de

When modeling astronomical objects throughout the universe, it is important to correctly treat the limitations of the data, for instance finite resolution and sensitivity. In order to simulate these effects, and to make radiative transfer models directly comparable to real observations, we have developed an open-source Python package called the FluxCompensator that enables the post-processing of the output of 3D Monte Carlo radiative transfer codes, such as Hyperion. With the FluxCompensator, realistic synthetic observations can be generated by modeling the effects of convolution with arbitrary point-spread functions, transmission curves, finite pixel resolution, noise, and reddening. Pipelines can be applied tomore » compute synthetic observations that simulate observatories, such as the Spitzer Space Telescope or the Herschel Space Observatory . Additionally, this tool can read in existing observations (e.g., FITS format) and use the same settings for the synthetic observations. In this paper, we describe the package as well as present examples of such synthetic observations.« less

The virtual mission approach: Empowering earth and space science missions

NASA Astrophysics Data System (ADS)

Hansen, Elaine

1993-08-01

Future Earth and Space Science missions will address increasingly broad and complex scientific issues. To accomplish this task, we will need to acquire and coordinate data sets from a number of different instrumetns, to make coordinated observations of a given phenomenon, and to coordinate the operation of the many individual instruments making these observations. These instruments will need to be used together as a single ``Virtual Mission.'' This coordinated approach is complicated in that these scientific instruments will generally be on different platforms, in different orbits, from different control centers, at different institutions, and report to different user groups. Before this Virtual Mission approach can be implemented, techniques need to be developed to enable separate instruments to work together harmoniously, to execute observing sequences in a synchronized manner, and to be managed by the Virtual Mission authority during times of these coordinated activities. Enabling technologies include object-oriented designed approaches, extended operations management concepts and distributed computing techniques. Once these technologies are developed and the Virtual Mission concept is available, we believe the concept will provide NASA's Science Program with a new, ``go-as-you-pay,'' flexible, and resilient way of accomplishing its science observing program. The concept will foster the use of smaller and lower cost satellites. It will enable the fleet of scientific satellites to evolve in directions that best meet prevailing science needs. It will empower scientists by enabling them to mix and match various combinations of in-space, ground, and suborbital instruments - combinations which can be called up quickly in response to new events or discoveries. And, it will enable small groups such as universities, Space Grant colleges, and small businesses to participate significantly in the program by developing small components of this evolving scientific fleet.

A Laboratory Goniometer System for Measuring Reflectance and Emittance Anisotropy

PubMed Central

Roosjen, Peter P. J.; Clevers, Jan G. P. W.; Bartholomeus, Harm M.; Schaepman, Michael E.; Schaepman-Strub, Gabriela; Jalink, Henk; van der Schoor, Rob; de Jong, Arjan

2012-01-01

In this paper, a laboratory goniometer system for performing multi-angular measurements under controlled illumination conditions is described. A commercially available robotic arm enables the acquisition of a large number of measurements over the full hemisphere within a short time span making it much faster than other goniometers. In addition, the presented set-up enables assessment of anisotropic reflectance and emittance behaviour of soils, leaves and small canopies. Mounting a spectrometer enables acquisition of either hemispherical measurements or measurements in the horizontal plane. Mounting a thermal camera allows directional observations of the thermal emittance. This paper also presents three showcases of these different measurement set-ups in order to illustrate its possibilities. Finally, suggestions for applying this instrument and for future research directions are given, including linking the measured reflectance anisotropy with physically-based anisotropy models on the one hand and combining them with field goniometry measurements for joint analysis with remote sensing data on the other hand. The speed and flexibility of the system offer a large added value to the existing pool of laboratory goniometers. PMID:23443402

A laboratory goniometer system for measuring reflectance and emittance anisotropy.

PubMed

Roosjen, Peter P J; Clevers, Jan G P W; Bartholomeus, Harm M; Schaepman, Michael E; Schaepman-Strub, Gabriela; Jalink, Henk; van der Schoor, Rob; de Jong, Arjan

2012-12-13

In this paper, a laboratory goniometer system for performing multi-angular measurements under controlled illumination conditions is described. A commercially available robotic arm enables the acquisition of a large number of measurements over the full hemisphere within a short time span making it much faster than other goniometers. In addition, the presented set-up enables assessment of anisotropic reflectance and emittance behaviour of soils, leaves and small canopies. Mounting a spectrometer enables acquisition of either hemispherical measurements or measurements in the horizontal plane. Mounting a thermal camera allows directional observations of the thermal emittance. This paper also presents three showcases of these different measurement set-ups in order to illustrate its possibilities. Finally, suggestions for applying this instrument and for future research directions are given, including linking the measured reflectance anisotropy with physically-based anisotropy models on the one hand and combining them with field goniometry measurements for joint analysis with remote sensing data on the other hand. The speed and flexibility of the system offer a large added value to the existing pool of laboratory goniometers.

A Prominence Puzzle Explained?

NASA Astrophysics Data System (ADS)

Yeates, A. R.; Mackay, D. H.; van Ballegooijen, A. A.

2009-02-01

Long-standing observations reveal a global organisation of the magnetic field direction in solar prominences (aka filaments), large clouds of cool dense plasma suspended in the Sun's hot corona. However, theorists have thus far been unable to explain the origin of this hemispheric pattern. In particular, simple shearing by large-scale surface motions would appear to lead to the wrong magnetic field direction. To explain the observations, we have developed a new model of the global magnetic field evolution in the solar corona over six months. For the first time our model can follow the build-up of magnetic helicity and shear on a global scale, driven by flux emergence and surface motions. The model is successful in predicting the correct magnetic field direction in the vast majority of prominences tested, and has enabled us to determine the key physical mechanisms behind the mysterious hemispheric pattern.

First Images from the Focusing Optics X-Ray Solar Imager

NASA Astrophysics Data System (ADS)

Krucker, Säm; Christe, Steven; Glesener, Lindsay; Ishikawa, Shin-nosuke; Ramsey, Brian; Takahashi, Tadayuki; Watanabe, Shin; Saito, Shinya; Gubarev, Mikhail; Kilaru, Kiranmayee; Tajima, Hiroyasu; Tanaka, Takaaki; Turin, Paul; McBride, Stephen; Glaser, David; Fermin, Jose; White, Stephen; Lin, Robert

2014-10-01

The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket payload flew for the first time on 2012 November 2, producing the first focused images of the Sun above 5 keV. To enable hard X-ray (HXR) imaging spectroscopy via direct focusing, FOXSI makes use of grazing-incidence replicated optics combined with fine-pitch solid-state detectors. On its first flight, FOXSI observed several targets that included active regions, the quiet Sun, and a GOES-class B2.7 microflare. This Letter provides an introduction to the FOXSI instrument and presents its first solar image. These data demonstrate the superiority in sensitivity and dynamic range that is achievable with a direct HXR imager with respect to previous, indirect imaging methods, and illustrate the technological readiness for a spaceborne mission to observe HXRs from solar flares via direct focusing optics.

Asymmetry hidden in birds’ tracks reveals wind, heading, and orientation ability over the ocean

PubMed Central

Goto, Yusuke; Yoda, Ken; Sato, Katsufumi

2017-01-01

Numerous flying and swimming animals constantly need to control their heading (that is, their direction of orientation) in a flow to reach their distant destination. However, animal orientation in a flow has yet to be satisfactorily explained because it is difficult to directly measure animal heading and flow. We constructed a new animal movement model based on the asymmetric distribution of the GPS (Global Positioning System) track vector along its mean vector, which might be caused by wind flow. This statistical model enabled us to simultaneously estimate animal heading (navigational decision-making) and ocean wind information over the range traversed by free-ranging birds. We applied this method to the tracking data of homing seabirds. The wind flow estimated by the model was consistent with the spatiotemporally coarse wind information provided by an atmospheric simulation model. The estimated heading information revealed that homing seabirds could head in a direction different from that leading to the colony to offset wind effects and to enable them to eventually move in the direction they intended to take, even though they are over the open sea where visual cues are unavailable. Our results highlight the utility of combining large data sets of animal movements with the “inverse problem approach,” enabling unobservable causal factors to be estimated from the observed output data. This approach potentially initiates a new era of analyzing animal decision-making in the field. PMID:28959724

Direct observation of lubricant additives using tomography techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yunyun; Sanchez, Carlos; Parkinson, Dilworth Y.

Lubricants play important roles in daily activities such as driving, walking, and cooking. The current understanding of mechanisms of lubrication, particularly in mechanical systems, has been limited by the lack of capability in direct observation. Here, we report an in situ approach to directly observe the motion of additive particles in grease under the influence of shear. Using the K-edge tomography technique, it is possible to detect particular additives in a grease and observe their distribution through 3D visualization. A commercial grease as a reference was studied with and without an inorganic additive of Fe{sub 3}O{sub 4} microparticles. The resultsmore » showed that it was possible to identify these particles and track their movement. Under a shear stress, Fe{sub 3}O{sub 4} particles were found to adhere to the edge of calcium complex thickeners commonly used in grease. Due to sliding, the grease formed a film with increased density. This approach enables in-line monitoring of a lubricant and future investigation in mechanisms of lubrication.« less

Apparatus for the Calibration/Certification of Direct Reading Tritium in Air Monitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Otlet, R.L.; Mather, I.D.; Pottinger, M

2005-07-15

Direct reading tritium-in-air-monitors are widely used for immediate observation of discharges or working area levels where significant sources of tritium are held. These monitors require initial and periodic calibration certification at the levels likely to be encountered. We describe a purpose built gas handling apparatus which enables various activity levels of tritiated gas ({sup 3}H + N{sub 2}) to be precisely metered and circulated in a closed loop through the monitor under calibration at a wide range of activity levels.

IR observations in gamma-ray blazars

NASA Technical Reports Server (NTRS)

Mahoney, W. A.; Gautier, T. N.; Ressler, M. E.; Wallyn, P.; Durouchoux, P.; Higdon, J. C.

1997-01-01

The infrared photometric and spectral observation of five gamma ray blazars in coordination with the energetic gamma ray experiment telescope (EGRET) onboard the Compton Gamma Ray Observatory is reported. The infrared measurements were made with a Cassegrain infrared camera and the mid-infrared large well imager at the Mt. Palomar 5 m telescope. The emphasis is on the three blazars observed simultaneously by EGRET and the ground-based telescope during viewing period 519. In addition to the acquisition of broadband spectral measurements for direct correlation with the 100 MeV EGRET observations, near infrared images were obtained, enabling a search for intra-day variability to be carried out.

Language evolution in the laboratory.

PubMed

Scott-Phillips, Thomas C; Kirby, Simon

2010-09-01

The historical origins of natural language cannot be observed directly. We can, however, study systems that support language and we can also develop models that explore the plausibility of different hypotheses about how language emerged. More recently, evolutionary linguists have begun to conduct language evolution experiments in the laboratory, where the emergence of new languages used by human participants can be observed directly. This enables researchers to study both the cognitive capacities necessary for language and the ways in which languages themselves emerge. One theme that runs through this work is how individual-level behaviours result in population-level linguistic phenomena. A central challenge for the future will be to explore how different forms of information transmission affect this process. 2010 Elsevier Ltd. All rights reserved.

A Handheld LED Coloured-Light Mixer for Students to Learn Collaboratively the Primary Colours of Light

ERIC Educational Resources Information Center

Nopparatjamjomras, Suchai; Chitaree, Ratchapak; Panijpan, Bhinyo

2009-01-01

To overcome students' inaccurate prior knowledge on primary additive colours, a coloured-light mixer has been constructed to enable students to observe directly the colours produced and reach the conclusion by themselves that the three primary colours of light are red, green, and blue (NOT red, yellow, and blue). Three closely packed tiny…

ARCADO - Adding random case analysis to direct observation in workplace-based formative assessment of general practice registrars.

PubMed

Ingham, Gerard; Fry, Jennifer; Morgan, Simon; Ward, Bernadette

2015-12-10

Workplace-based formative assessments using consultation observation are currently conducted during the Australian general practice training program. Assessment reliability is improved by using multiple assessment methods. The aim of this study was to explore experiences of general practice medical educator assessors and registrars (trainees) when adding random case analysis to direct observation (ARCADO) during formative workplace-based assessments. A sample of general practice medical educators and matched registrars were recruited. Following the ARCADO workplace assessment, semi-structured qualitative interviews were conducted. The data was analysed thematically. Ten registrars and eight medical educators participated. Four major themes emerged - formative versus summative assessment; strengths (acceptability, flexibility, time efficiency, complementarity and authenticity); weaknesses (reduced observation and integrity risks); and contextual factors (variation in assessment content, assessment timing, registrar-medical educator relationship, medical educator's approach and registrar ability). ARCADO is a well-accepted workplace-based formative assessment perceived by registrars and assessors to be valid and flexible. The use of ARCADO enabled complementary insights that would not have been achieved with direct observation alone. Whilst there are some contextual factors to be considered in its implementation, ARCADO appears to have utility as formative assessment and, subject to further evaluation, high-stakes assessment.

THE IMPACT OF ACCURATE EXTINCTION MEASUREMENTS FOR X-RAY SPECTRAL MODELS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Randall K.; Valencic, Lynne A.; Corrales, Lia, E-mail: lynne.a.valencic@nasa.gov

Interstellar extinction includes both absorption and scattering of photons from interstellar gas and dust grains, and it has the effect of altering a source's spectrum and its total observed intensity. However, while multiple absorption models exist, there are no useful scattering models in standard X-ray spectrum fitting tools, such as XSPEC. Nonetheless, X-ray halos, created by scattering from dust grains, are detected around even moderately absorbed sources, and the impact on an observed source spectrum can be significant, if modest, compared to direct absorption. By convolving the scattering cross section with dust models, we have created a spectral model asmore » a function of energy, type of dust, and extraction region that can be used with models of direct absorption. This will ensure that the extinction model is consistent and enable direct connections to be made between a source's X-ray spectral fits and its UV/optical extinction.« less

FIRST IMAGES FROM THE FOCUSING OPTICS X-RAY SOLAR IMAGER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krucker, Säm; Glesener, Lindsay; Turin, Paul

2014-10-01

The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket payload flew for the first time on 2012 November 2, producing the first focused images of the Sun above 5 keV. To enable hard X-ray (HXR) imaging spectroscopy via direct focusing, FOXSI makes use of grazing-incidence replicated optics combined with fine-pitch solid-state detectors. On its first flight, FOXSI observed several targets that included active regions, the quiet Sun, and a GOES-class B2.7 microflare. This Letter provides an introduction to the FOXSI instrument and presents its first solar image. These data demonstrate the superiority in sensitivity and dynamic range that is achievable with amore » direct HXR imager with respect to previous, indirect imaging methods, and illustrate the technological readiness for a spaceborne mission to observe HXRs from solar flares via direct focusing optics.« less

Towards an understanding of the attributes of simulation that enable learning in undergraduate nurse education: A grounded theory study.

PubMed

Bland, Andrew J; Tobbell, Jane

2016-09-01

Simulation has become an established feature of nurse education yet little is understood about the mechanisms that lead to learning. To explore the attributes of simulation-based education that enable student learning in undergraduate nurse education. Final year students drawn from one UK University (n=46) participated in a grounded theory study. First, nonparticipant observation and video recording of student activity was undertaken. Following initial analysis, recordings and observations were deconstructed during focus group interviews that enabled both the researcher and participants to unpack meaning. Lastly emergent findings were verified with final year students drawn from a second UK University (n=6). A staged approach to learning emerged from engagement in simulation. This began with initial hesitation as students moved through nonlinear stages to making connections and thinking like a nurse. Core findings suggest that simulation enables curiosity and intellect (main concern) through doing (core category) and interaction with others identified as social collaboration (category). This study offers a theoretical basis for understanding simulation-based education and integration of strategies that maximise the potential for learning. Additionally it offers direction for further research, particularly with regards to how the application of theory to practice is accelerated through learning by doing and working collaboratively. Copyright © 2016 Elsevier Ltd. All rights reserved.

A new FIB fabrication method for micropillar specimens for three-dimensional observation using scanning transmission electron microscopy.

PubMed

Fukuda, Muneyuki; Tomimatsu, Satoshi; Nakamura, Kuniyasu; Koguchi, Masanari; Shichi, Hiroyasu; Umemura, Kaoru

2004-01-01

A new method to prepare micropillar specimens with a high aspect ratio that is suitable for three-dimensional scanning transmission electron microscopy (3D-STEM) was developed. The key features of the micropillar fabrication are: first, microsampling to extract a small piece including the structure of interest in an IC chip, and second, an ion-beam with an incident direction of 60 degrees to the pillar's axis that enables the parallel sidewalls of the pillar to be produced with a high aspect ratio. A memory-cell structure (length: 6 microm; width: 300 x 500 nm) was fabricated in the micropillar and observed from various directions with a 3D-STEM. A planiform capacitor covered with granular surfaces and a solid crossing gate and metal lines was successfully observed threedimensionally at a resolution of approximately 5 nm.

Visualization of migration of human cortical neurons generated from induced pluripotent stem cells.

PubMed

Bamba, Yohei; Kanemura, Yonehiro; Okano, Hideyuki; Yamasaki, Mami

2017-09-01

Neuronal migration is considered a key process in human brain development. However, direct observation of migrating human cortical neurons in the fetal brain is accompanied by ethical concerns and is a major obstacle in investigating human cortical neuronal migration. We established a novel system that enables direct visualization of migrating cortical neurons generated from human induced pluripotent stem cells (hiPSCs). We observed the migration of cortical neurons generated from hiPSCs derived from a control and from a patient with lissencephaly. Our system needs no viable brain tissue, which is usually used in slice culture. Migratory behavior of human cortical neuron can be observed more easily and more vividly by its fluorescence and glial scaffold than that by earlier methods. Our in vitro experimental system provides a new platform for investigating development of the human central nervous system and brain malformation. Copyright © 2017 Elsevier B.V. All rights reserved.

The SPEDE spectrometer

NASA Astrophysics Data System (ADS)

Papadakis, P.; Cox, D. M.; O'Neill, G. G.; Borge, M. J. G.; Butler, P. A.; Gaffney, L. P.; Greenlees, P. T.; Herzberg, R.-D.; Illana, A.; Joss, D. T.; Konki, J.; Kröll, T.; Ojala, J.; Page, R. D.; Rahkila, P.; Ranttila, K.; Thornhill, J.; Tuunanen, J.; Van Duppen, P.; Warr, N.; Pakarinen, J.

2018-03-01

The electron spectrometer, SPEDE, has been developed and will be employed in conjunction with the Miniball spectrometer at the HIE-ISOLDE facility, CERN. SPEDE allows for direct measurement of internal conversion electrons emitted in-flight, without employing magnetic fields to transport or momentum filter the electrons. Together with the Miniball spectrometer, it enables simultaneous observation of γ rays and conversion electrons in Coulomb excitation experiments using radioactive ion beams.

Meteorological Observations and System Performance From the NASA D3R's First 5 Years

NASA Technical Reports Server (NTRS)

Chandrasekar, V.; Beauchamp, Robert M.; Vega, Manuel; Chen, Haonan; Kumar, Mohit; Joshil, Shashank; Schwaller, Mathew; Petersen, Walter; Wolff, David

2017-01-01

The NASA dual-frequency, dual-polarization, Doppler radar (D3R) was conceived and developed to support ground validation (GV) operations of the Global Precipitation Measurement (GPM) mission. The D3R operates in the same frequencies bands, Ku- and Ka-band, as GPMs dual-frequency precipitation radar enabling direct comparisons of microphysical observations of precipitation. To support the GPM GVmission, D3R substantively participated in four field campaigns in North America with diverse geographic features covering both winter and summer conditions.

An Observation Analysis Tool for time-series analysis and sensor management in the FREEWAT GIS environment for water resources management

NASA Astrophysics Data System (ADS)

Cannata, Massimiliano; Neumann, Jakob; Cardoso, Mirko; Rossetto, Rudy; Foglia, Laura; Borsi, Iacopo

2017-04-01

In situ time-series are an important aspect of environmental modelling, especially with the advancement of numerical simulation techniques and increased model complexity. In order to make use of the increasing data available through the requirements of the EU Water Framework Directive, the FREEWAT GIS environment incorporates the newly developed Observation Analysis Tool for time-series analysis. The tool is used to import time-series data into QGIS from local CSV files, online sensors using the istSOS service, or MODFLOW model result files and enables visualisation, pre-processing of data for model development, and post-processing of model results. OAT can be used as a pre-processor for calibration observations, integrating the creation of observations for calibration directly from sensor time-series. The tool consists in an expandable Python library of processing methods and an interface integrated in the QGIS FREEWAT plug-in which includes a large number of modelling capabilities, data management tools and calibration capacity.

Direct quantum process tomography via measuring sequential weak values of incompatible observables.

PubMed

Kim, Yosep; Kim, Yong-Su; Lee, Sang-Yun; Han, Sang-Wook; Moon, Sung; Kim, Yoon-Ho; Cho, Young-Wook

2018-01-15

The weak value concept has enabled fundamental studies of quantum measurement and, recently, found potential applications in quantum and classical metrology. However, most weak value experiments reported to date do not require quantum mechanical descriptions, as they only exploit the classical wave nature of the physical systems. In this work, we demonstrate measurement of the sequential weak value of two incompatible observables by making use of two-photon quantum interference so that the results can only be explained quantum physically. We then demonstrate that the sequential weak value measurement can be used to perform direct quantum process tomography of a qubit channel. Our work not only demonstrates the quantum nature of weak values but also presents potential new applications of weak values in analyzing quantum channels and operations.

An Unroofing Method to Observe the Cytoskeleton Directly at Molecular Resolution Using Atomic Force Microscopy

PubMed Central

Usukura, Eiji; Narita, Akihiro; Yagi, Akira; Ito, Shuichi; Usukura, Jiro

2016-01-01

An improved unroofing method enabled the cantilever of an atomic force microscope (AFM) to reach directly into a cell to visualize the intracellular cytoskeletal actin filaments, microtubules, clathrin coats, and caveolae in phosphate-buffered saline (PBS) at a higher resolution than conventional electron microscopy. All of the actin filaments clearly exhibited a short periodicity of approximately 5–6 nm, which was derived from globular actins linked to each other to form filaments, as well as a long helical periodicity. The polarity of the actin filaments appeared to be determined by the shape of the periodic striations. Microtubules were identified based on their thickness. Clathrin coats and caveolae were observed on the cytoplasmic surface of cell membranes. The area containing clathrin molecules and their terminal domains was directly visualized. Characteristic ridge structures located at the surface of the caveolae were observed at high resolution, similar to those observed with electron microscopy (EM). Overall, unroofing allowed intracellular AFM imaging in a liquid environment with a level of quality equivalent or superior to that of EM. Thus, AFMs are anticipated to provide cutting-edge findings in cell biology and histology. PMID:27273367

Using modern imaging techniques to old HST data: a summary of the ALICE program.

NASA Astrophysics Data System (ADS)

Choquet, Elodie; Soummer, Remi; Perrin, Marshall; Pueyo, Laurent; Hagan, James Brendan; Zimmerman, Neil; Debes, John Henry; Schneider, Glenn; Ren, Bin; Milli, Julien; Wolff, Schuyler; Stark, Chris; Mawet, Dimitri; Golimowski, David A.; Hines, Dean C.; Roberge, Aki; Serabyn, Eugene

2018-01-01

Direct imaging of extrasolar systems is a powerful technique to study the physical properties of exoplanetary systems and understand their formation and evolution mechanisms. The detection and characterization of these objects are challenged by their high contrast with their host star. Several observing strategies and post-processing algorithms have been developed for ground-based high-contrast imaging instruments, enabling the discovery of directly-imaged and spectrally-characterized exoplanets. The Hubble Space Telescope (HST), pioneer in directly imaging extrasolar systems, has yet been often limited to the detection of bright debris disks systems, with sensitivity limited by the difficulty to implement an optimal PSF subtraction stategy, which is readily offered on ground-based telescopes in pupil tracking mode.The Archival Legacy Investigations of Circumstellar Environments (ALICE) program is a consistent re-analysis of the 10 year old coronagraphic archive of HST's NICMOS infrared imager. Using post-processing methods developed for ground-based observations, we used the whole archive to calibrate PSF temporal variations and improve NICMOS's detection limits. We have now delivered ALICE-reprocessed science products for the whole NICMOS archival data back to the community. These science products, as well as the ALICE pipeline, were used to prototype the JWST coronagraphic data and reduction pipeline. The ALICE program has enabled the detection of 10 faint debris disk systems never imaged before in the near-infrared and several substellar companion candidates, which we are all in the process of characterizing through follow-up observations with both ground-based facilities and HST-STIS coronagraphy. In this publication, we provide a summary of the results of the ALICE program, advertise its science products and discuss the prospects of the program.

Direct observation of morphological evolution of a catalyst during carbon nanotube forest growth: new insights into growth and growth termination

NASA Astrophysics Data System (ADS)

Jeong, Seojeong; Lee, Jaegeun; Kim, Hwan-Chul; Hwang, Jun Yeon; Ku, Bon-Cheol; Zakharov, Dmitri N.; Maruyama, Benji; Stach, Eric A.; Kim, Seung Min

2016-01-01

In this study, we develop a new methodology for transmission electron microscopy (TEM) analysis that enables us to directly investigate the interface between carbon nanotube (CNT) arrays and the catalyst and support layers for CNT forest growth without any damage induced by a post-growth TEM sample preparation. Using this methodology, we perform in situ and ex situ TEM investigations on the evolution of the morphology of the catalyst particles and observe the catalyst particles to climb up through CNT arrays during CNT forest growth. We speculate that the lifted catalysts significantly affect the growth and growth termination of CNT forests along with Ostwald ripening and sub-surface diffusion. Thus, we propose a modified growth termination model which better explains various phenomena related to the growth and growth termination of CNT forests.In this study, we develop a new methodology for transmission electron microscopy (TEM) analysis that enables us to directly investigate the interface between carbon nanotube (CNT) arrays and the catalyst and support layers for CNT forest growth without any damage induced by a post-growth TEM sample preparation. Using this methodology, we perform in situ and ex situ TEM investigations on the evolution of the morphology of the catalyst particles and observe the catalyst particles to climb up through CNT arrays during CNT forest growth. We speculate that the lifted catalysts significantly affect the growth and growth termination of CNT forests along with Ostwald ripening and sub-surface diffusion. Thus, we propose a modified growth termination model which better explains various phenomena related to the growth and growth termination of CNT forests. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05547d

Experimental observation of the stratified electrothermal instability on aluminum with thickness greater than a skin depth

NASA Astrophysics Data System (ADS)

Hutchinson, T. M.; Awe, T. J.; Bauer, B. S.; Yates, K. C.; Yu, E. P.; Yelton, W. G.; Fuelling, S.

2018-05-01

A direct observation of the stratified electrothermal instability on the surface of thick metal is reported. Aluminum rods coated with 70 μ m Parylene-N were driven to 1 MA in 100 ns , with the metal thicker than the skin depth. The dielectric coating suppressed plasma formation, enabling persistent observation of discrete azimuthally correlated stratified thermal perturbations perpendicular to the current whose wave numbers, k , grew exponentially with rate γ (k ) =0.06 n s-1-(0.4 n s-1μ m2ra d-2 ) k2 in ˜1 g /c m3 , ˜7000 K aluminum.

Supersymmetry and Kaon physics

NASA Astrophysics Data System (ADS)

Yamamoto, Kei

2017-01-01

Kaon physics has played an essential role in testing the Standard Model and in searching for new physics with measurements of CP violation and rare decays. Current progress of lattice calculations enables us to predict kaon observables accurately, especially for the direct CP violation, ε‧/ε, and there is a discrepancy from the experimental data at the 2.9 σ level. On the experimental side, the rare kaon decays and are ongoing to be measured at the SM accuracy by KOTO at J-PARC and NA62 at CERN. These kaon observables are good probes for new physics. We study supersymmetric effects; the chargino and gluino contributions to Z penguin, in kaon observables.

Archiving strategy for USGS EROS center and our future direction

USGS Publications Warehouse

Faundeen, John L.

2010-01-01

The U. S. Geological Survey's Earth Resources Observation and Science Center has the responsibility to acquire, manage, and preserve our Nation's land observations. These records are obtained primarily from airplanes and satellites dating back to the 1930s. The ability to compare landscapes from the past with current information enables change analysis at local and global scales. With new observations added daily, the records management challenges are daunting, involving petabytes of electronic data and tens of thousands of rolls of analog film. This paper focuses upon the appraisal and preservation functions employed to ensure that these records are available for current and future generations.

Experimental Observation of the Stratified Electrothermal Instability on Aluminum with Thickness Greater than a Skin Depth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hutchinson, Trevor M.; Hutchinson, Trevor M.; Awe, Thomas James

The first direct observation of the stratified electrothermal instability on the surface of thick metal is reported. Aluminum rods coated with 70 μm Parylene-N were driven to 1 MA in approximately 100 ns, with the metal thicker than the skin depth. The dielectric coating suppressed plasma formation, enabling persistent observation of discrete azimuthally-correlated stratified structures perpendicular to the current. Strata amplitudes grow rapidly, while their Fourier spectrum shifts toward longer wavelength. Assuming blackbody emission, radiometric calculations indicate strata are temperature perturbations that grow exponentially with rate γ = 0.04 ns -1 in 3000- 10,000 K aluminum.

Scalable Total Syntheses of N-Linked Tryptamine Dimers by Direct Indole-Aniline Coupling: Psychotrimine and Kapakahines B & F

PubMed Central

Newhouse, Timothy; Lewis, Chad A.; Eastman, Kyle J.; Baran, Phil S.

2010-01-01

This report details the invention of a method to enable syntheses of psychotrimine, 1, and the kapakahines F and B, 2 & 3, on a gram scale and in a minimum number of steps. Mechanistic inquiries are presented for the key enabling quaternization of indole at the C3 position by electrophilic attack of an activated aniline species. Excellent chemo-, regio-, and diastereoselectivities are observed for reactions with o-iodoaniline, an indole cation equivalent. Additionally, the scope of this reaction is broad with respect to the tryptamine and aniline components. The anti-cancer profiles of psychotrimine, 1, and kapakahines F and B, 2 & 3, have also been evaluated. PMID:20426477

Synchrotron X-ray micro-tomography at the Advanced Light Source: Developments in high-temperature in-situ mechanical testing

NASA Astrophysics Data System (ADS)

Barnard, Harold S.; MacDowell, A. A.; Parkinson, D. Y.; Mandal, P.; Czabaj, M.; Gao, Y.; Maillet, E.; Blank, B.; Larson, N. M.; Ritchie, R. O.; Gludovatz, B.; Acevedo, C.; Liu, D.

2017-06-01

At the Advanced Light Source (ALS), Beamline 8.3.2 performs hard X-ray micro-tomography under conditions of high temperature, pressure, mechanical loading, and other realistic conditions using environmental test cells. With scan times of 10s-100s of seconds, the microstructural evolution of materials can be directly observed over multiple time steps spanning prescribed changes in the sample environment. This capability enables in-situ quasi-static mechanical testing of materials. We present an overview of our in-situ mechanical testing capabilities and recent hardware developments that enable flexural testing at high temperature and in combination with acoustic emission analysis.

Isolation of Campylobacter from Brazilian broiler flocks using different culturing procedures.

PubMed

Vaz, C S L; Voss-Rech, D; Pozza, J S; Coldebella, A; Silva, V S

2014-11-01

Conventional culturing methods enable the detection of Campylobacter in broiler flocks. However, laboratory culture of Campylobacter is laborious because of its fastidious behavior and the presence of competing nontarget bacteria. This study evaluated different protocols to isolate Campylobacter from broiler litter, feces, and cloacal and drag swabs. Samples taken from commercial Brazilian broiler flocks were directly streaked onto Preston agar (PA), Campy-Line agar (CLA), and modified charcoal cefoperazone deoxycholate agar (mCCDA) and also enriched in blood-free Bolton broth (bfBB) for 24 and 48 h followed by plating onto the different selective media. Higher numbers of Campylobacter-positive cloacal and drag swab samples were observed using either direct plating or enrichment for 24 h before plating onto PA, compared with enrichment for 48 h (P < 0.05). Furthermore, direct plating was a more sensitive method to detect Campylobacter in broiler litter and feces samples. Analysis of directly plated samples revealed that higher Campylobacter levels were detected in feces streaked onto PA (88.8%), cloacal swabs plated onto mCCDA (72.2%), drag swabs streaked onto CLA or mCCDA (69.4%), and litter samples inoculated onto PA (63.8%). Preston agar was the best agar to isolate Campylobacter from directly plated litter samples (P < 0.05), but there was no difference in the efficacies of PA, mCCDA, and CLA in detecting Campylobacter in other samples. The isolated Campylobacter strains were phenotypically identified as Campylobacter jejuni or Campylobacter coli. The predominant contaminant observed in the Campylobacter cultures was Proteus mirabilis, which was resistant to the majority of antimicrobial agents in selective media. Together, these data showed that direct plating onto PA and onto either CLA or mCCDA as the second selective agar enabled the reliable isolation of thermophilic Campylobacter species from broiler samples. Finally, Campylobacter was detected in all broiler flocks sampled. ©2014 Poultry Science Association Inc.

­­MMS Observations of a Hot Flow Anomaly in the Magnetosheath

NASA Astrophysics Data System (ADS)

Zhang, H.; Le, G.; Sibeck, D. G.

2017-12-01

Hot flow anomalies (HFAs) are events observed near planetary bow shocks that are characterized by greatly heated solar wind plasmas and substantial flow deflection. HFAs are universal phenomena that have been observed near the bow shock of Earth, Venus, Mars, and Saturn. The dynamic pressure inside HFAs is lower than the ambient solar wind due to the density depletion and flow deflection. The passage of HFAs will therefore result in local negative pressure impulses, which lead to a local sunward expansion of the magnetopause. NASA's MMS mission produce unprecedented high resolution data, which enable the observations of HFA structures in great details. We report MMS observations of an HFA in the post-noon magnetosheath which lasted 25 minutes. Sunward and dawnward plasma flow was observed in the core of the HFA, which is in the opposite direction of the plasma flow in the ambient magnetosheath. The plasma density in the HFA was about one order of magnitude lower than that in the ambient magnetosheath. Two magnetopause crossings were observed inside the HFA. Boundary normal analysis shows the normal direction of the magnetopause was along the GSE Y direction, indicating a strongly deformed magnetopause. The first in, first out crossing sequence of the magnetopause by multiple spacecraft also indicates that the two magnetopause crossings were due to a bulged-out magnetopause rather than the back and forth motion of the magnetopause.

Gibbsite Growth History — Revelations of a New Scanning Electron Microscope Technique

NASA Astrophysics Data System (ADS)

Roach, Gerald I. D.; Cornell, John B.; Griffin, Brendan J.

A new scanning electron microscope technique termed charge contrast imaging (CCI), unique to the Environmental SEM, has been developed at the Centre for Microscopy and Microanalysis. The technique enables the growth history of gibbsite particles from the Bayer process to be studied. The technique is used on uncoated polished sections. The seed gibbsite is clearly distinguished from freshly precipitated gibbsite enabling information on agglomeration and growth to be unambiguously obtained. Growth rings associated with each pass through precipitation are readily observed which enables the complete growth history of a particle to be ascertained; for example batch and continuously grown gibbsites can be distinguished. Growth of gibbsite on different crystal faces can be directly measured and the presence of secondary nucleation detected. The data obtained via this technique have been confirmed using specially prepared laboratory samples. The technique is now finding wider application in areas such as medicine (examination of kidney stones), mineralogy and ceramics.

Strain-engineered inverse charge-funnelling in layered semiconductors.

PubMed

De Sanctis, Adolfo; Amit, Iddo; Hepplestone, Steven P; Craciun, Monica F; Russo, Saverio

2018-04-25

The control of charges in a circuit due to an external electric field is ubiquitous to the exchange, storage and manipulation of information in a wide range of applications. Conversely, the ability to grow clean interfaces between materials has been a stepping stone for engineering built-in electric fields largely exploited in modern photovoltaics and opto-electronics. The emergence of atomically thin semiconductors is now enabling new ways to attain electric fields and unveil novel charge transport mechanisms. Here, we report the first direct electrical observation of the inverse charge-funnel effect enabled by deterministic and spatially resolved strain-induced electric fields in a thin sheet of HfS 2 . We demonstrate that charges driven by these spatially varying electric fields in the channel of a phototransistor lead to a 350% enhancement in the responsivity. These findings could enable the informed design of highly efficient photovoltaic cells.

Intraoperative Fluorescence Cerebral Angiography by Laser Surgical Microscopy: Comparison With Xenon Microscopy and Simultaneous Observation of Cerebral Blood Flow and Surrounding Structures.

PubMed

Ito, Yuhei; Suzuki, Kyouichi; Ichikawa, Tsuyoshi; Watanabe, Yoichi; Sato, Taku; Sakuma, Jun; Saito, Kiyoshi

2018-06-12

Laser surgical microscopes should enable uniform illumination of the operative field, and require less luminous energy compared with existing xenon surgical microscopes. To examine the utility of laser illumination in fluorescence cerebral angiography. Fluorescein sodium (fluorescein) was used as a fluorescent dye. We first compared the clarity of cerebral blood flow images collected by fluorescence angiography between the laser illumination and xenon illumination methods. We then assessed use of the laser illuminator for simultaneous observation of blood flow and surrounding structures during fluorescence angiography. Furthermore, the study was designed to evaluate usefulness of the thus determined excitation light in clinical cases. Fluorescence angiography using blue light laser for excitation provided higher clarity and contrast blood flow images compared with using blue light generated from a xenon lamp. Further, illumination with excitation light consisting of a combination of 3 types of laser (higher level of blue light, no green light, and lower level of red light) enabled both blood flow and surrounding structures to be observed through the microscope directly by the surgeon. Laser-illuminated fluorescence angiography provides high clarity and contrast images of cerebral blood flow. Further, a laser providing strong blue light and weak red light for excitation light enables simultaneous visual observation of fluorescent blood flow and surrounding structures by the surgeon using a surgical microscope. Overall, these data suggest that laser surgical microscopes are useful for both ordinary operative manipulations and fluorescence angiography.

The DART Cylindrical, Infrared, 1 Meter Membrane Reflector

NASA Technical Reports Server (NTRS)

Morgan, Rhonda M.; Agnes, Greg S.; Barber, Dan; Dooley, Jennifer; Dragovan, Mark; Hatheway, Al E.; Marcin, Marty

2004-01-01

The Dual Anamorphic Reflector Telescopes (DART) is an architecture for large aperture space telescopes that enables the use of membranes. A membrane can be readily shaped in one direction of curvature using a combination of boundary control and tensioning, yielding a cylindrical reflector. Two cylindrical reflectors (orthogonal and confocal) comprise the 'primary mirror' of the telescope system. The aperture is completely unobstructed and ideal for infrared and high contrast observations.

Direct amide formation using radiofrequency heating.

PubMed

Houlding, Thomas K; Tchabanenko, Kirill; Rahman, Md Taifur; Rebrov, Evgeny V

2013-07-07

We present a simple method for direct and solvent-free formation of amides from carboxylic acids and amines using radiofrequency heating. The direct energy coupling of the AC magnetic field via nickel ferrite magnetic nanoparticles enables fast and controllable heating, as well as enabling facile work-up via magnetic separation.

Flight paths of seabirds soaring over the ocean surface enable measurement of fine-scale wind speed and direction.

PubMed

Yonehara, Yoshinari; Goto, Yusuke; Yoda, Ken; Watanuki, Yutaka; Young, Lindsay C; Weimerskirch, Henri; Bost, Charles-André; Sato, Katsufumi

2016-08-09

Ocean surface winds are an essential factor in understanding the physical interactions between the atmosphere and the ocean. Surface winds measured by satellite scatterometers and buoys cover most of the global ocean; however, there are still spatial and temporal gaps and finer-scale variations of wind that may be overlooked, particularly in coastal areas. Here, we show that flight paths of soaring seabirds can be used to estimate fine-scale (every 5 min, ∼5 km) ocean surface winds. Fine-scale global positioning system (GPS) positional data revealed that soaring seabirds flew tortuously and ground speed fluctuated presumably due to tail winds and head winds. Taking advantage of the ground speed difference in relation to flight direction, we reliably estimated wind speed and direction experienced by the birds. These bird-based wind velocities were significantly correlated with wind velocities estimated by satellite-borne scatterometers. Furthermore, extensive travel distances and flight duration of the seabirds enabled a wide range of high-resolution wind observations, especially in coastal areas. Our study suggests that seabirds provide a platform from which to measure ocean surface winds, potentially complementing conventional wind measurements by covering spatial and temporal measurement gaps.

Flight paths of seabirds soaring over the ocean surface enable measurement of fine-scale wind speed and direction

PubMed Central

Yonehara, Yoshinari; Goto, Yusuke; Yoda, Ken; Watanuki, Yutaka; Young, Lindsay C.; Weimerskirch, Henri; Bost, Charles-André; Sato, Katsufumi

2016-01-01

Ocean surface winds are an essential factor in understanding the physical interactions between the atmosphere and the ocean. Surface winds measured by satellite scatterometers and buoys cover most of the global ocean; however, there are still spatial and temporal gaps and finer-scale variations of wind that may be overlooked, particularly in coastal areas. Here, we show that flight paths of soaring seabirds can be used to estimate fine-scale (every 5 min, ∼5 km) ocean surface winds. Fine-scale global positioning system (GPS) positional data revealed that soaring seabirds flew tortuously and ground speed fluctuated presumably due to tail winds and head winds. Taking advantage of the ground speed difference in relation to flight direction, we reliably estimated wind speed and direction experienced by the birds. These bird-based wind velocities were significantly correlated with wind velocities estimated by satellite-borne scatterometers. Furthermore, extensive travel distances and flight duration of the seabirds enabled a wide range of high-resolution wind observations, especially in coastal areas. Our study suggests that seabirds provide a platform from which to measure ocean surface winds, potentially complementing conventional wind measurements by covering spatial and temporal measurement gaps. PMID:27457932

Cinemicrographic study of the cell movement in the primitive-streak-stage mouse embryo.

PubMed

Nakatsuji, N; Snow, M H; Wylie, C C

1986-07-01

Migration of the mesoderm cells in the primitive-streak-stage mouse embryo was directly studied by cinemicrography using whole embryo culture and Nomarski differential interference contrast optics. Relative transparency and small size of the early mouse embryos enabled direct observation of the individual cells and their cell processes. Seven-day-old mouse embryos were isolated and cultured in a small chamber in a medium consisting of 50% rat serum and 50% Dulbecco's modified minimum essential medium. The mesoderm cells move away from the primitive streak in both anterior and antimesometrial (distal) directions at a mean velocity of 46 micron h-1. They extend cell processes and constantly change cell shape. They do not translocate extensively as isolated single cells, but usually maintain attachment to other mesoderm cells. They show frequent cell division preceded by rounding up of the cell bodies, and accompanied by vigorous blebbing before and after cytokinesis. This study shows that it is possible to examine the motility of embryonic cells inside the mammalian embryo by direct observation if the embryo is small and transparent enough for the use of the Nomarski optics.

Nano-structured wild moth cocoon fibers as radiative cooling and waveguiding optical materials

NASA Astrophysics Data System (ADS)

Shi, Norman Nan; Tsai, Cheng-Chia; Bernard, Gary D.; Craig, Catherine; Yu, Nanfang

2017-09-01

The study shows that comet moth cocoon fibers exhibit radiative cooing properties with enhanced solar reflectivity and thermal emissivity. Nanostructured voids inside the cocoon fiber enables the cocoons to exhibit strong scattering in the visible and near-infrared. These structures also allow the fibers to exhibit strong shape birefringence and directional reflectivity. Optical waveguiding due to transverse Anderson localization is observed in these natural fibers, where the invariance and large concentration of the voids in the longitudinal direction allow the fiber to confine light in the transverse direction. To mimic the optical effects generated by these natural silk fibers, nanostructured voids are introduced into regenerated silk fibers through wet spinning to enhance reflectivity in the solar spectrum.

New fluorescence correlation spectroscopy enabling direct observation of spatiotemporal dependence of diffusion constants as an evidence of anomalous transport in extracellular matrices.

PubMed

Masuda, Akiko; Ushida, Kiminori; Okamoto, Takayuki

2005-05-01

The potential of fluorescence correlation spectroscopy (FCS) is extended to enable the direct observation of anomalous subdiffusion (ASD) in inhomogeneous media that are of great importance particularly in many biological systems, such as membranes, cytoplasm, and extracellular matrices (ECMs). Because ASD can be confirmed by monitoring the spatiotemporal dependence of observable diffusion coefficients (D(obs)), the size of the effective confocal volume (V(eff)) for FCS sampling (sampling volume) was continuously changed on a scale of 300-500 nm using a motorized variable beam expander through which an illuminating laser beam passes. This new method, namely, sampling-volume-controlled (SVC)-FCS, was applied to the analysis of hyaluronan (HA) aqueous solutions where the D(obs) of light-emitting solute (Alexa 488) markedly changed, corresponding to the change in V(eff) (220-340 nm in the half-axis), because the network structure of HA of 7-33 nm (nanostructure) interferes with the material transport within it. The results indicate that moderate ASD may occur even in the presence of a small amount ( approximately 0.1 wt %) of HA in ECM. Because the change in D(obs) along with the traveling distance (the mean-square displacement) can be identified even in systems with no deformation of the autocorrelation function, this technique has a great potential for general applications to many biological systems in which ASD shows complex time and space dependences.

The mirror system and its role in social cognition.

PubMed

Rizzolatti, Giacomo; Fabbri-Destro, Maddalena

2008-04-01

Experiments in monkeys have shown that coding the goal of the motor acts is a fundamental property of the cortical motor system. In area F5, goal-coding motor neurons are also activated by observing motor acts done by others (the 'classical' mirror mechanism); in area F2 and area F1, some motor neurons are activated by the mere observation of goal-directed movements of a cursor displayed on a computer screen (a 'mirror-like' mechanism). Experiments in humans and monkeys have shown that the mirror mechanism enables the observer to understand the intention behind an observed motor act, in addition to the goal of it. Growing evidence shows that a deficit in the mirror mechanism underlies some aspects of autism.

Analysis of fatty acids by graphite plate laser desorption/ionization time-of-flight mass spectrometry.

PubMed

Park, K H; Kim, H J

2001-01-01

Fatty acids obtained from triglycerides (trioelin, tripalmitin), foods (milk, corn oil), and phospholipids (phosphotidylcholine, phosphotidylserine, phosphatidic acid) upon alkaline hydrolysis were observed directly without derivatization by graphite plate laser desorption/ionization time-of-flight mass spectrometry (GPLDI-TOFMS). Mass-to-charge ratios predicted for sodium adducts of expected fatty acids (e.g. palmitic, oleic, linoleic and arachidonic acids) were observed without interference. Although at present no quantitation is possible, the graphite plate method enables a simple and rapid qualitative analysis of fatty acids. Copyright 2001 John Wiley & Sons, Ltd.

Investigation of laser irradiation of WC-Co cemented carbides inside a scanning electron microscope (LASEM)

NASA Astrophysics Data System (ADS)

Schultrich, B.; Wetzig, K.

1987-09-01

A combination of SEM and laser enables direct observation of structural modifications by a high-energy input. With this new device, melting phenomena and fracture processes in a WC-6 percent Co hard metal were investigated. The first laser pulse leads to melting of a thin surface layer with the formation of blisters and craters. Cracking is induced by the relaxation of compressive surface stresses during the high-temperature stage and the appearance of tensile stresses during cooling. Besides crack formation and extension, complete welding of crack surfaces was observed after repeated laser irradiation.

Internal sub-sonic burning during an explosion viewed via dynamic X-ray radiography

NASA Astrophysics Data System (ADS)

Smilowitz, L.; Henson, B. F.; Oschwald, D.; Suvorova, N.; Remelius, D.

2017-10-01

We observe internal convective and conductive burn front propagation and solid consumption subsequent to thermal ignition for plastic bonded formulations of the solid organic secondary explosives octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine and 1,3,5-triamino-2,4,6-trinitrobenzene. This work describes x-ray radiographic diagnostics enabling the study of solid density in a fully encased explosive during internal burning subsequent to ignition. The result of this study is the ability to directly observe and measure rates of energy release during a thermal explosion.

Direct Band Gap Wurtzite Gallium Phosphide Nanowires

PubMed Central

2013-01-01

The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555–690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

Reconfigurable and writable magnetic charge crystals

DOEpatents

Wang, Yong-Lei; Xiao, Zhi-Li; Kwok, Wai-Kwong

2017-07-18

Artificial ices enable the study of geometrical frustration by design and through direct observation. It has, however, proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. An artificial spin structure design is described that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. A technique is also developed to precisely manipulate the local magnetic charge states and demonstrate write-read-erase multi-functionality at room temperature. This globally reconfigurable and locally writable magnetic charge ice provides a setting for designing magnetic monopole defects, tailoring magnetics and controlling the properties of other two-dimensional materials.

Microbial competition between Bacillus subtilis and Staphylococcus aureus monitored by imaging mass spectrometry

PubMed Central

Gonzalez, David J.; Haste, Nina M.; Hollands, Andrew; Fleming, Tinya C.; Hamby, Matthew; Pogliano, Kit; Nizet, Victor

2011-01-01

Microbial competition exists in the general environment, such as soil or aquatic habitats, upon or within unicellular or multicellular eukaryotic life forms. The molecular actions that govern microbial competition, leading to niche establishment and microbial monopolization, remain undetermined. The emerging technology of imaging mass spectrometry (IMS) enabled the observation that there is directionality in the metabolic output of the organism Bacillus subtilis when co-cultured with Staphylococcus aureus. The directionally released antibiotic alters S. aureus virulence factor production and colonization. Therefore, IMS provides insight into the largely hidden nature of competitive microbial encounters and niche establishment, and provides a paradigm for future antibiotic discovery. PMID:21719540

Rewritable artificial magnetic charge ice

DOE PAGES

Wang, Yong-Lei; Xiao, Zhi-Li; Snezhko, Alexey; ...

2016-05-20

Artificial ices enable the study of geometrical frustration by design and through direct observation. However, it has proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. Here, we designed an artificial spin structure that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. We also developed a technique to precisely manipulate the local magnetic charge states and demonstrate write-read-erase multifunctionality at room temperature. This globally reconfigurable and locally writable magnetic charge ice could provide a setting for designing magnetic monopole defects, tailoring magnonics, and controlling the propertiesmore » of other two-dimensional materials.« less

Local nanoscale strain mapping of a metallic glass during in situ testing

NASA Astrophysics Data System (ADS)

Gammer, Christoph; Ophus, Colin; Pekin, Thomas C.; Eckert, Jürgen; Minor, Andrew M.

2018-04-01

The local elastic strains during tensile deformation in a CuZrAlAg metallic glass are obtained by fitting an elliptic shape function to the characteristic amorphous ring in electron diffraction patterns. Scanning nanobeam electron diffraction enables strain mapping with a resolution of a few nanometers. Here, a fast direct electron detector is used to acquire the diffraction patterns at a sufficient speed to map the local transient strain during continuous tensile loading in situ in the transmission electron microscope. The elastic strain in tensile direction was found to increase during loading. After catastrophic fracture, a residual elastic strain that relaxes over time was observed.

Rewritable artificial magnetic charge ice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yong-Lei; Xiao, Zhi-Li; Snezhko, Alexey

Artificial ices enable the study of geometrical frustration by design and through direct observation. However, it has proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. Here, we designed an artificial spin structure that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. We also developed a technique to precisely manipulate the local magnetic charge states and demonstrate write-read-erase multifunctionality at room temperature. This globally reconfigurable and locally writable magnetic charge ice could provide a setting for designing magnetic monopole defects, tailoring magnonics, and controlling the propertiesmore » of other two-dimensional materials.« less

Direct Observations of Interstellar H, He, and O by the Interstellar Boundary Explorer (Invited)

NASA Astrophysics Data System (ADS)

Moebius, E.; Bochsler, P. A.; Bzowski, M.; Crew, G. B.; Funsten, H. O.; Fuselier, S. A.; Ghielmetti, A.; Heirtzler, D.; Izmodenov, V.; Kubiak, M.; Kucharek, H.; Lee, M. A.; Leonard, T.; McComas, D. J.; Petersen, L.; Saul, L. A.; Scheer, J.; Schwadron, N. A.; Witte, M.; Wurz, P.

2009-12-01

Due to the motion of the Sun relative to its neighborhood, the neutral gas of the local in-terstellar medium (LISM) flows through the inner heliosphere where it is subject to ioni-zation, the Sun’s gravity, and radiation pressure. Observing the resulting spatial distribu-tion and flow pattern of several interstellar gas species with UV backscatter, pickup ion, and neutral atom imaging techniques allows us to unravel the physical conditions of the LISM and its interaction with the heliosphere. Imaging of the neutral gas flow directly with energetic neutral atom (ENA) cameras yields the most accurate account of the ki-netic parameters of the interstellar gas, but so far this has been carried out only for He using Ulysses GAS. IBEX, which was launched in October 2008, provides the capability for simultaneous flow observations of several interstellar species with its triple-time-of-flight IBEX-Lo sensor. Because H and O are strongly affected by the heliospheric inter-face while He is not, a direct comparison between these species enables an independent assessment of the slowdown and heating processes in the outer heliosheath. Likewise, IBEX observations will constrain models of the heliospheric interaction and provide a test of the heliospheric asymmetry - recently inferred from Voyager and SOHO SWAN observations - that is seen as an indicator for the interstellar magnetic field direction. During the first half year of its mission IBEX has observed the interstellar He, O, and H flow. We will present an overview and preliminary analysis of these first interstellar mul-tispecies scans of the interstellar gas flow in spring and fall 2009.

Processing-in-Memory Enabled Graphics Processors for 3D Rendering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Chenhao; Song, Shuaiwen; Wang, Jing

2017-02-06

The performance of 3D rendering of Graphics Processing Unit that convents 3D vector stream into 2D frame with 3D image effects significantly impact users’ gaming experience on modern computer systems. Due to the high texture throughput in 3D rendering, main memory bandwidth becomes a critical obstacle for improving the overall rendering performance. 3D stacked memory systems such as Hybrid Memory Cube (HMC) provide opportunities to significantly overcome the memory wall by directly connecting logic controllers to DRAM dies. Based on the observation that texel fetches significantly impact off-chip memory traffic, we propose two architectural designs to enable Processing-In-Memory based GPUmore » for efficient 3D rendering.« less

Broadband surface plasmon jets: direct observation of plasmon propagation for application to sensors and optical communications in microscale and nanoscale circuitry

DOEpatents

Bouhelier, Alexandre [Westmont, IL; Wiederrecht, Gary P [Elmhurst, IL

2008-02-19

A system and method for generating and using broadband surface plasmons in a metal film for characterization of analyte on or near the metal film. The surface plasmons interact with the analyte and generate leakage radiation which has spectral features which can be used to inspect, identify and characterize the analyte. The broadband plasmon excitation enables high-bandwidth photonic applications.

Long-range sound-mediated dark-soliton interactions in trapped atomic condensates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, A. J.; Jackson, D. P.; Barenghi, C. F.

2011-01-15

A long-range soliton interaction is discussed whereby two or more dark solitons interact in an inhomogeneous atomic condensate, modifying their respective dynamics via the exchange of sound waves without ever coming into direct contact. An idealized double-well geometry is shown to yield perfect energy transfer and complete periodic identity reversal of the two solitons. Two experimentally relevant geometries are analyzed which should enable the observation of this long-range interaction.

Observing New Worlds with Space Telescopes

NASA Technical Reports Server (NTRS)

Clampin, Mark

2011-01-01

The search for exoplanets and characterization of their properties has seen increasing success over the last few years. In excess of 500 explanets are known and there are approximately 1200 additional candidates. Recently, progress has been made in direct imaging planets, both from the ground and in space. This presentation will discuss the history and current state of technology used for such discoveries, and highlight the new results enabled by the current and future space telescopes.

Direct Observations of Fracture and the Damage Mechanics of Ceramics

DTIC Science & Technology

1988-10-31

microplasticity up to the fracture load. d. It shculd have low enough strength in tension and compression to enable strength measurements at easily accessible...15jm. SEM examination of the grains after large amounts of deformation indicated that the grains are brittle without any evidence of microplasticity . In...and microplasticity in polycrystalline alumina", J.Mater.Sci., 12(1977)791-796. 93. J Lankford, "Compressive microfracture and indentation damage in A1

Direct observation of interfacial Au atoms on TiO₂ in three dimensions.

PubMed

Gao, Wenpei; Sivaramakrishnan, Shankar; Wen, Jianguo; Zuo, Jian-Min

2015-04-08

Interfacial atoms, which result from interactions between the metal nanoparticles and support, have a large impact on the physical and chemical properties of nanoparticles. However, they are difficult to observe; the lack of knowledge has been a major obstacle toward unraveling their role in chemical transformations. Here we report conclusive evidence of interfacial Au atoms formed on the rutile (TiO2) (110) surfaces by activation using high-temperature (∼500 °C) annealing in air. Three-dimensional imaging was performed using depth-sectioning enabled by aberration-corrected scanning transmission electron microscopy. Results show that the interface between Au nanocrystals and TiO2 (110) surfaces consists of a single atomic layer with Au atoms embedded inside Ti-O. The number of interfacial Au atoms is estimated from ∼1-8 in an interfacial atomic column. Direct impact of interfacial Au atoms is observed on an enhanced Au-TiO2 interaction and the reduction of surface TiO2; both are critical to Au catalysis.

Brownian motion of tethered nanowires.

PubMed

Ota, Sadao; Li, Tongcang; Li, Yimin; Ye, Ziliang; Labno, Anna; Yin, Xiaobo; Alam, Mohammad-Reza; Zhang, Xiang

2014-05-01

Brownian motion of slender particles near a boundary is ubiquitous in biological systems and in nanomaterial assembly, but the complex hydrodynamic interaction in those systems is still poorly understood. Here, we report experimental and computational studies of the Brownian motion of silicon nanowires tethered on a substrate. An optical interference method enabled direct observation of microscopic rotations of the slender bodies in three dimensions with high angular and temporal resolutions. This quantitative observation revealed anisotropic and angle-dependent hydrodynamic wall effects: rotational diffusivity in inclined and azimuth directions follows different power laws as a function of the length, ∼ L(-2.5) and ∼ L(-3), respectively, and is more hindered for smaller inclined angles. In parallel, we developed an implicit simulation technique that takes the complex wire-wall hydrodynamic interactions into account efficiently, the result of which agreed well with the experimentally observed angle-dependent diffusion. The demonstrated techniques provide a platform for studying the microrheology of soft condensed matters, such as colloidal and biological systems near interfaces, and exploring the optimal self-assembly conditions of nanostructures.

Automated Data Quality Assurance using OGC Sensor Web Enablement Frameworks for Marine Observatories

NASA Astrophysics Data System (ADS)

Toma, Daniel; Bghiel, Ikram; del Rio, Joaquin; Hidalgo, Alberto; Carreras, Normandino; Manuel, Antoni

2014-05-01

Over the past years, environmental sensors have continuously improved by becoming smaller, cheaper, and more intelligent. Therefore, many sensor networks are increasingly deployed to monitor our environment. But due to the large number of sensor manufacturers, accompanying protocols and data encoding, automated integration and data quality assurance of diverse sensors in an observing systems is not straightforward, requiring development of data management code and manual tedious configuration. However, over the past few years it has been demonstrated that Open-Geospatial Consortium (OGC) frameworks can enable web services with fully-described sensor systems, including data processing, sensor characteristics and quality control tests and results. So far, the SWE framework does not describe how to integrate sensors on-the-fly with minimal human intervention. The data management software which enables access to sensors, data processing and quality control tests has to be implemented and the results have to be manually mapped to the SWE models. In this contribution, we describe a Sensor Plug & Play infrastructure for the Sensor Web by combining (1) OGC PUCK protocol - a simple standard embedded instrument protocol to store and retrieve directly from the devices the declarative description of sensor characteristics and quality control tests, (2) an automatic mechanism for data processing and quality control tests underlying the Sensor Web - the Sensor Interface Descriptor (SID) concept, as well as (3) a model for the declarative description of sensor which serves as a generic data management mechanism - designed as a profile and extension of OGC SWE's SensorML standard. We implement and evaluate our approach by applying it to the OBSEA Observatory, and can be used to demonstrate the ability to assess data quality for temperature, salinity, air pressure and wind speed and direction observations off the coast of Garraf, in the north-eastern Spain.

Estimation of chromatic errors from broadband images for high contrast imaging: sensitivity analysis

NASA Astrophysics Data System (ADS)

Sirbu, Dan; Belikov, Ruslan

2016-01-01

Many concepts have been proposed to enable direct imaging of planets around nearby stars, and which would enable spectroscopic observations of their atmospheric observations and the potential discovery of biomarkers. The main technical challenge associated with direct imaging of exoplanets is to effectively control both the diffraction and scattered light from the star so that the dim planetary companion can be seen. Usage of an internal coronagraph with an adaptive optical system for wavefront correction is one of the most mature methods and is being developed as an instrument addition to the WFIRST-AFTA space mission. In addition, such instruments as GPI and SPHERE are already being used on the ground and are yielding spectra of giant planets. For the deformable mirror (DM) to recover a dark hole region with sufficiently high contrast in the image plane, mid-spatial frequency wavefront errors must be estimated. To date, most broadband lab demonstrations use narrowband filters to obtain an estimate of the the chromaticity of the wavefront error and this can result in usage of a large percentage of the total integration time. Previously, we have proposed a method to estimate the chromaticity of wavefront errors using only broadband images; we have demonstrated that under idealized conditions wavefront errors can be estimated from images composed of discrete wavelengths. This is achieved by using DM probes with sufficient spatially-localized chromatic diversity. Here we report on the results of a study of the performance of this method with respect to realistic broadband images including noise. Additionally, we study optimal probe patterns that enable reduction of the number of probes used and compare the integration time with narrowband and IFS estimation methods.

New modes of electron microscopy for materials science enabled by fast direct electron detectors

NASA Astrophysics Data System (ADS)

Minor, Andrew

There is an ongoing revolution in the development of electron detector technology that has enabled modes of electron microscopy imaging that had only before been theorized. The age of electron microscopy as a tool for imaging is quickly giving way to a new frontier of multidimensional datasets to be mined. These improvements in electron detection have enabled cryo-electron microscopy to resolve the three-dimensional structures of non-crystalized proteins, revolutionizing structural biology. In the physical sciences direct electron detectors has enabled four-dimensional reciprocal space maps of materials at atomic resolution, providing all the structural information about nanoscale materials in one experiment. This talk will highlight the impact of direct electron detectors for materials science, including a new method of scanning nanobeam diffraction. With faster detectors we can take a series of 2D diffraction patterns at each position in a 2D STEM raster scan resulting in a four-dimensional data set. For thin film analysis, direct electron detectors hold the potential to enable strain, polarization, composition and electrical field mapping over relatively large fields of view, all from a single experiment.

A study of phase defect measurement on EUV mask by multiple detectors CD-SEM

NASA Astrophysics Data System (ADS)

Yonekura, Isao; Hakii, Hidemitsu; Morisaki, Shinya; Murakawa, Tsutomu; Shida, Soichi; Kuribara, Masayuki; Iwai, Toshimichi; Matsumoto, Jun; Nakamura, Takayuki

2013-06-01

We have studied MVM (Multi Vision Metrology) -SEM® E3630 to measure 3D shape of defects. The four detectors (Detector A, B, C and D) are independently set up in symmetry for the primary electron beam axis. Signal processing of four direction images enables not only 2D (width) measurement but also 3D (height) measurement. At last PMJ, we have investigated the relation between the E3630's signal of programmed defect on MoSi-HT and defect height measured by AFM (Atomic Force Microscope). It was confirmed that height of integral profile by this tool is correlated with AFM. It was tested that E3630 has capability of observing multilayer defect on EUV. We have investigated correlation with AFM of width and depth or height of multilayer defect. As the result of observing programmed defects, it was confirmed that measurement result by E3630 is well correlated with AFM. And the function of 3D view image enables to show nm order defect.

Correlative Analysis of Behavioral and Physiological Concomitants of Labor in Pregnant Rats

NASA Technical Reports Server (NTRS)

Baer, L. A.; Wade, C. E.; Ronca, A. E.; Dalton, Bonnie (Technical Monitor)

2002-01-01

During parturition, rats exhibit characteristic behavioral expressions of labor. Lordosis contractions, consisting of an elongation of the dams body, are observed beginning several hours prior to neonate births, whereas vertical contractions, repeated rapid lifts of the abdomen, occur immediately preceding the birth of each neonate. We analyzed underlying changes in intrauterine pressure (IUP) using a telemetric sensor that we modified for use in freely-moving rats. This technique enabled us to correlate behavioral expressions of labor contractions with IUP. A small telemetric blood pressure sensor was fitted within a fluid-filled balloon, similar in size to a full term rat fetus. On Gestational day 19 of the rats' 22-day pregnancy, a unit was surgically implanted within the uterus. The dams were simultaneously videotaped, enabling us to directly correlate IUP signals with behavioral expressions of labor contractions. Earlier phases of labor, consisting predominantly of lordosis contractions were characterized by lower pressures relative to later phases during which higher pressures and vertical contractions were frequently observed.

First light with Trident: multi-platform synthetic quasar spectra

NASA Astrophysics Data System (ADS)

Silvia, Devin W.; Hummels, Cameron B.; Smith, Britton

2017-01-01

Observational efforts to better understand the nature of the intergalactic and circumgalactic media have relied heavily on the information encoded in the absorption line systems of quasar spectra. Numerical simulations of large-scale structure and galaxy evolution are well-suited to explore the properties of those same media owing to the relative ease with which one can access physical quantities from complex, three-dimensional data. However, a difficulty arises when one tries to make direct “apple-to-apples” comparisons between observed spectra and simulated data. In an effort to provide a common language capable of linking theory and observation, we announce the release of Trident. Trident is a publicly available software tool that enables the creation of realistic synthetic absorption spectra from virtually all widely-used hydrodynamics simulation codes. Through user-controlled levels of spectral realism, direct comparisons between simulated and observed data become not only possible, but greatly simplified. We present the methods for extracting artificial quasar sightlines and generating spectra as well as early-stage applications of those spectra to intergalactic and circumgalactic absorption line studies.

Using direct clinical observation to assess the quality of cesarean delivery in Afghanistan: an exploratory study

PubMed Central

2014-01-01

Background As part of a National Emergency Obstetric and Newborn Care (EmONC) Needs Assessment, a special study was undertaken in July 2010 to examine the quality of cesarean deliveries in Afghanistan and examine the utility of direct clinical observation as an assessment method in low-resource settings. Methods This cross-sectional assessment of the quality of cesareans at 14 facilities in Afghanistan included a survey of surgeons regarding their routine cesarean practices, direct observation of 29 cesarean deliveries and comparison of observations with facility records for 34 additional cesareans conducted during the 3 days prior to the observation period at each facility. For both observed cases and record reviews, we assessed time intervals between specified points of care-arrival to the ward, first evaluation, detection of a complication, decision for cesarean, incision, and birth. Results All time intervals with the exception of “decision to skin incision” were longer in the record reviews than in observed cases. Prior cesarean was the most common primary indication for all cases. All mothers in both groups observed survived through one hour postpartum. Among newborns there were two stillbirths (7%) in observed births and seven (21%) record reviews. Although our sample is too small to show statistical significance, the difference is noteworthy. In six of the reviewed cesareans resulting in stillbirth, a fetal heart rate was recorded in the operating theater, although four were recorded as macerated. For the two fresh stillbirths, the cesarean surgeries were recorded as scheduled and not urgent. Conclusions Direct observation of cesarean deliveries enabled us to assess a number of preoperative, postoperative, and intraoperative procedures that are often not described in medical records in low resource settings. Comparison of observations with findings from provider interviews and facility records allowed us to infer whether observed practices were typical of providers and facilities and detect potential Hawthorne effects. PMID:24886143

Local protein solvation drives direct down-conversion in phycobiliprotein PC645 via incoherent vibronic transport

PubMed Central

Blau, Samuel M.; Bennett, Doran I. G.; Kreisbeck, Christoph; Scholes, Gregory D.; Aspuru-Guzik, Alán

2018-01-01

The mechanisms controlling excitation energy transport (EET) in light-harvesting complexes remain controversial. Following the observation of long-lived beats in 2D electronic spectroscopy of PC645, vibronic coherence, the delocalization of excited states between pigments supported by a resonant vibration, has been proposed to enable direct excitation transport from the highest-energy to the lowest-energy pigments, bypassing a collection of intermediate states. Here, we instead show that for phycobiliprotein PC645 an incoherent vibronic transport mechanism is at play. We quantify the solvation dynamics of individual pigments using ab initio quantum mechanics/molecular mechanics (QM/MM) nuclear dynamics. Our atomistic spectral densities reproduce experimental observations ranging from absorption and fluorescence spectra to the timescales and selectivity of down-conversion observed in transient absorption measurements. We construct a general model for vibronic dimers and establish the parameter regimes of coherent and incoherent vibronic transport. We demonstrate that direct down-conversion in PC645 proceeds incoherently, enhanced by large reorganization energies and a broad collection of high-frequency vibrations. We suggest that a similar incoherent mechanism is appropriate across phycobiliproteins and represents a potential design principle for nanoscale control of EET. PMID:29588417

A gravitational-wave standard siren measurement of the Hubble constant.

PubMed

2017-11-02

On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817-a strong signal from the merger of a binary neutron-star system. Less than two seconds after the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO-Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identification of an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first 'multi-messenger' astronomical observation. Such observations enable GW170817 to be used as a 'standard siren' (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic 'distance ladder': the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. This value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision.

A gravitational-wave standard siren measurement of the Hubble constant

NASA Astrophysics Data System (ADS)

Abbott, B. P.; Abbott, R.; Abbott, T. D.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Afrough, M.; Agarwal, B.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allen, G.; Allocca, A.; Altin, P. A.; Amato, A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Angelova, S. V.; Antier, S.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Atallah, D. V.; Aufmuth, P.; Aulbert, C.; Aultoneal, K.; Austin, C.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Bae, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Banagiri, S.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barkett, K.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bawaj, M.; Bayley, J. C.; Bazzan, M.; Bécsy, B.; Beer, C.; Bejger, M.; Belahcene, I.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Bero, J. J.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Biscoveanu, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bode, N.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonilla, E.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bossie, K.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Bustillo, J. Calderón; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Canizares, P.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Carney, M. F.; Diaz, J. Casanueva; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerdá-Durán, P.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chase, E.; Chassande-Mottin, E.; Chatterjee, D.; Chatziioannou, K.; Cheeseboro, B. D.; Chen, H. Y.; Chen, X.; Chen, Y.; Cheng, H.-P.; Chia, H.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, A. K. W.; Chung, S.; Ciani, G.; Ciolfi, R.; Cirelli, C. E.; Cirone, A.; Clara, F.; Clark, J. A.; Clearwater, P.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P.-F.; Cohen, D.; Colla, A.; Collette, C. G.; Cominsky, L. R.; Constancio, M.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt, T. R.; Cordero-Carrión, I.; Corley, K. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Dálya, G.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; da Silva Costa, C. F.; Datrier, L. E. H.; Dattilo, V.; Dave, I.; Davier, M.; Davis, D.; Daw, E. J.; Day, B.; de, S.; Debra, D.; Degallaix, J.; de Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Demos, N.; Denker, T.; Dent, T.; de Pietri, R.; Dergachev, V.; De Rosa, R.; Derosa, R. T.; de Rossi, C.; Desalvo, R.; de Varona, O.; Devenson, J.; Dhurandhar, S.; Díaz, M. C.; di Fiore, L.; di Giovanni, M.; di Girolamo, T.; di Lieto, A.; di Pace, S.; di Palma, I.; di Renzo, F.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Dovale Álvarez, M.; Downes, T. P.; Drago, M.; Dreissigacker, C.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dupej, P.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Estevez, D.; Etienne, Z. B.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fee, C.; Fehrmann, H.; Feicht, J.; Fejer, M. M.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Finstad, D.; Fiori, I.; Fiorucci, D.; Fishbach, M.; Fisher, R. P.; Fitz-Axen, M.; Flaminio, R.; Fletcher, M.; Fong, H.; Font, J. A.; Forsyth, P. W. F.; Forsyth, S. S.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Ganija, M. R.; Gaonkar, S. G.; Garcia-Quiros, C.; Garufi, F.; Gateley, B.; Gaudio, S.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, D.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glover, L.; Goetz, E.; Goetz, R.; Gomes, S.; Goncharov, B.; González, G.; Castro, J. M. Gonzalez; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Gretarsson, E. M.; Groot, P.; Grote, H.; Grunewald, S.; Gruning, P.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Halim, O.; Hall, B. R.; Hall, E. D.; Hamilton, E. Z.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hannuksela, O. A.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hinderer, T.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Horst, C.; Hough, J.; Houston, E. A.; Howell, E. J.; Hreibi, A.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Inta, R.; Intini, G.; Isa, H. N.; Isac, J.-M.; Isi, M.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kamai, B.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katolik, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kawabe, K.; Kéfélian, F.; Keitel, D.; Kemball, A. J.; Kennedy, R.; Kent, C.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, K.; Kim, W.; Kim, W. S.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kinley-Hanlon, M.; Kirchhoff, R.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Knowles, T. D.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Krämer, C.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kumar, S.; Kuo, L.; Kutynia, A.; Kwang, S.; Lackey, B. D.; Lai, K. H.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Linker, S. D.; Littenberg, T. B.; Liu, J.; Liu, X.; Lo, R. K. L.; Lockerbie, N. A.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lovelace, G.; Lück, H.; Lumaca, D.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macas, R.; Macfoy, S.; Machenschalk, B.; Macinnis, M.; MacLeod, D. M.; Hernandez, I. Magaña; Magaña-Sandoval, F.; Zertuche, L. Magaña; Magee, R. M.; Majorana, E.; Maksimovic, I.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markakis, C.; Markosyan, A. S.; Markowitz, A.; Maros, E.; Marquina, A.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Mason, K.; Massera, E.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matas, A.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McCuller, L.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McNeill, L.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Mejuto-Villa, E.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, B. B.; Miller, J.; Millhouse, M.; Milovich-Goff, M. C.; Minazzoli, O.; Minenkov, Y.; Ming, J.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moffa, D.; Moggi, A.; Mogushi, K.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muñiz, E. A.; Muratore, M.; Murray, P. G.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Neilson, J.; Nelemans, G.; Nelson, T. J. N.; Nery, M.; Neunzert, A.; Nevin, L.; Newport, J. M.; Newton, G.; Ng, K. K. Y.; Nguyen, T. T.; Nichols, D.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; North, C.; Nuttall, L. K.; Oberling, J.; O'Dea, G. D.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Okada, M. A.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; Ormiston, R.; Ortega, L. F.; O'Shaughnessy, R.; Ossokine, S.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Page, M. A.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, Howard; Pan, Huang-Wei; Pang, B.; Pang, P. T. H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Parida, A.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patil, M.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pirello, M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Porter, E. K.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Pratten, G.; Predoi, V.; Prestegard, T.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rajbhandari, B.; Rakhmanov, M.; Ramirez, K. E.; Ramos-Buades, A.; Rapagnani, P.; Raymond, V.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Ren, W.; Reyes, S. D.; Ricci, F.; Ricker, P. M.; Rieger, S.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romel, C. L.; Romie, J. H.; Rosińska, D.; Ross, M. P.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Rutins, G.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sanchez, L. E.; Sanchis-Gual, N.; Sandberg, V.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheel, M.; Scheuer, J.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schulte, B. W.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Seidel, E.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D. A.; Shaffer, T. J.; Shah, A. A.; Shahriar, M. S.; Shaner, M. B.; Shao, L.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, L. P.; Singh, A.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Smith, R. J. E.; Somala, S.; Son, E. J.; Sonnenberg, J. A.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staats, K.; Staley, A.; Steer, D.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stevenson, S. P.; Stone, R.; Stops, D. J.; Strain, K. A.; Stratta, G.; Strigin, S. E.; Strunk, A.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Suresh, J.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Tait, S. C.; Talbot, C.; Talukder, D.; Tanner, D. B.; Tápai, M.; Taracchini, A.; Tasson, J. D.; Taylor, J. A.; Taylor, R.; Tewari, S. V.; Theeg, T.; Thies, F.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tonelli, M.; Tornasi, Z.; Torres-Forné, A.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tsang, K. W.; Tse, M.; Tso, R.; Tsukada, L.; Tsuna, D.; Tuyenbayev, D.; Ueno, K.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; van den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walet, R.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, J. Z.; Wang, W. H.; Wang, Y. F.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wessel, E. K.; Weßels, P.; Westerweck, J.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; Whiting, B. F.; Whittle, C.; Wilken, D.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Wofford, J.; Wong, K. W. K.; Worden, J.; Wright, J. L.; Wu, D. S.; Wysocki, D. M.; Xiao, S.; Yamamoto, H.; Yancey, C. C.; Yang, L.; Yap, M. J.; Yazback, M.; Yu, Hang; Yu, Haocun; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zelenova, T.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y.-H.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, S. J.; Zhu, X. J.; Zimmerman, A. B.; Zucker, M. E.; Zweizig, J.; Foley, R. J.; Coulter, D. A.; Drout, M. R.; Kasen, D.; Kilpatrick, C. D.; Madore, B. F.; Murguia-Berthier, A.; Pan, Y.-C.; Piro, A. L.; Prochaska, J. X.; Ramirez-Ruiz, E.; Rest, A.; Rojas-Bravo, C.; Shappee, B. J.; Siebert, M. R.; Simon, J. D.; Ulloa, N.; Annis, J.; Soares-Santos, M.; Brout, D.; Scolnic, D.; Diehl, H. T.; Frieman, J.; Berger, E.; Alexander, K. D.; Allam, S.; Balbinot, E.; Blanchard, P.; Butler, R. E.; Chornock, R.; Cook, E. R.; Cowperthwaite, P.; Drlica-Wagner, A.; Drout, M. R.; Durret, F.; Eftekhari, T.; Finley, D. A.; Fong, W.; Fryer, C. L.; García-Bellido, J.; Gill, M. S. S.; Gruendl, R. A.; Hanna, C.; Hartley, W.; Herner, K.; Huterer, D.; Kasen, D.; Kessler, R.; Li, T. S.; Lin, H.; Lopes, P. A. A.; Lourenço, A. C. C.; Margutti, R.; Marriner, J.; Marshall, J. L.; Matheson, T.; Medina, G. E.; Metzger, B. D.; Muñoz, R. R.; Muir, J.; Nicholl, M.; Nugent, P.; Palmese, A.; Paz-Chinchón, F.; Quataert, E.; Sako, M.; Sauseda, M.; Schlegel, D. J.; Secco, L. F.; Smith, N.; Sobreira, F.; Stebbins, A.; Villar, V. A.; Vivas, A. K.; Wester, W.; Williams, P. K. G.; Yanny, B.; Zenteno, A.; Abbott, T. M. C.; Abdalla, F. B.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Bridle, S. L.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Castander, F. J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Davis, C.; Depoy, D. L.; Desai, S.; Dietrich, J. P.; Estrada, J.; Fernandez, E.; Flaugher, B.; Fosalba, P.; Gaztanaga, E.; Gerdes, D. W.; Giannantonio, T.; Goldstein, D. A.; Gruen, D.; Gutierrez, G.; Hartley, W. G.; Honscheid, K.; Jain, B.; James, D. J.; Jeltema, T.; Johnson, M. W. G.; Kent, S.; Krause, E.; Kron, R.; Kuehn, K.; Kuhlmann, S.; Kuropatkin, N.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Miller, C. J.; Miquel, R.; Neilsen, E.; Nord, B.; Ogando, R. L. C.; Plazas, A. A.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Smith, R. C.; Suchyta, E.; Tarle, G.; Thomas, D.; Thomas, R. C.; Troxel, M. A.; Tucker, D. L.; Vikram, V.; Walker, A. R.; Weller, J.; Zhang, Y.; Haislip, J. B.; Kouprianov, V. V.; Reichart, D. E.; Tartaglia, L.; Sand, D. J.; Valenti, S.; Yang, S.; Arcavi, Iair; Hosseinzadeh, Griffin; Howell, D. Andrew; McCully, Curtis; Poznanski, Dovi; Vasylyev, Sergiy; Tanvir, N. R.; Levan, A. J.; Hjorth, J.; Cano, Z.; Copperwheat, C.; de Ugarte-Postigo, A.; Evans, P. A.; Fynbo, J. P. U.; González-Fernández, C.; Greiner, J.; Irwin, M.; Lyman, J.; Mandel, I.; McMahon, R.; Milvang-Jensen, B.; O'Brien, P.; Osborne, J. P.; Perley, D. A.; Pian, E.; Palazzi, E.; Rol, E.; Rosetti, S.; Rosswog, S.; Rowlinson, A.; Schulze, S.; Steeghs, D. T. H.; Thöne, C. C.; Ulaczyk, K.; Watson, D.; Wiersema, K.; Lipunov, V. M.; Gorbovskoy, E.; Kornilov, V. G.; Tyurina, N.; Balanutsa, P.; Vlasenko, D.; Gorbunov, I.; Podesta, R.; Levato, H.; Saffe, C.; Buckley, D. A. H.; Budnev, N. M.; Gress, O.; Yurkov, V.; Rebolo, R.; Serra-Ricart, M.

2017-11-01

On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817—a strong signal from the merger of a binary neutron-star system. Less than two seconds after the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO-Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identification of an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first ‘multi-messenger’ astronomical observation. Such observations enable GW170817 to be used as a ‘standard siren’ (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic ‘distance ladder’: the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. This value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision.

Perceptual learning modifies untrained pursuit eye movements.

PubMed

Szpiro, Sarit F A; Spering, Miriam; Carrasco, Marisa

2014-07-07

Perceptual learning improves detection and discrimination of relevant visual information in mature humans, revealing sensory plasticity. Whether visual perceptual learning affects motor responses is unknown. Here we implemented a protocol that enabled us to address this question. We tested a perceptual response (motion direction estimation, in which observers overestimate motion direction away from a reference) and a motor response (voluntary smooth pursuit eye movements). Perceptual training led to greater overestimation and, remarkably, it modified untrained smooth pursuit. In contrast, pursuit training did not affect overestimation in either pursuit or perception, even though observers in both training groups were exposed to the same stimuli for the same time period. A second experiment revealed that estimation training also improved discrimination, indicating that overestimation may optimize perceptual sensitivity. Hence, active perceptual training is necessary to alter perceptual responses, and an acquired change in perception suffices to modify pursuit, a motor response. © 2014 ARVO.

Perceptual learning modifies untrained pursuit eye movements

PubMed Central

Szpiro, Sarit F. A.; Spering, Miriam; Carrasco, Marisa

2014-01-01

Perceptual learning improves detection and discrimination of relevant visual information in mature humans, revealing sensory plasticity. Whether visual perceptual learning affects motor responses is unknown. Here we implemented a protocol that enabled us to address this question. We tested a perceptual response (motion direction estimation, in which observers overestimate motion direction away from a reference) and a motor response (voluntary smooth pursuit eye movements). Perceptual training led to greater overestimation and, remarkably, it modified untrained smooth pursuit. In contrast, pursuit training did not affect overestimation in either pursuit or perception, even though observers in both training groups were exposed to the same stimuli for the same time period. A second experiment revealed that estimation training also improved discrimination, indicating that overestimation may optimize perceptual sensitivity. Hence, active perceptual training is necessary to alter perceptual responses, and an acquired change in perception suffices to modify pursuit, a motor response. PMID:25002412

Cosmic curvature tested directly from observations

NASA Astrophysics Data System (ADS)

Denissenya, Mikhail; Linder, Eric V.; Shafieloo, Arman

2018-03-01

Cosmic spatial curvature is a fundamental geometric quantity of the Universe. We investigate a model independent, geometric approach to measure spatial curvature directly from observations, without any derivatives of data. This employs strong lensing time delays and supernova distance measurements to measure the curvature itself, rather than just testing consistency with flatness. We define two curvature estimators, with differing error propagation characteristics, that can crosscheck each other, and also show how they can be used to map the curvature in redshift slices, to test constancy of curvature as required by the Robertson-Walker metric. Simulating realizations of redshift distributions and distance measurements of lenses and sources, we estimate uncertainties on the curvature enabled by next generation measurements. The results indicate that the model independent methods, using only geometry without assuming forms for the energy density constituents, can determine the curvature at the ~6×10‑3 level.

Gauge-free gyrokinetic theory

NASA Astrophysics Data System (ADS)

Burby, Joshua; Brizard, Alain

2017-10-01

Test-particle gyrocenter equations of motion play an essential role in the diagnosis of turbulent strongly-magnetized plasmas, and are playing an increasingly-important role in the formulation of kinetic-gyrokinetic hybrid models. Previous gyrocenter models required the knowledge of the perturbed electromagnetic potentials, which are not directly observable quantities (since they are gauge-dependent). A new gauge-free formulation of gyrocenter motion is presented, which enables gyrocenter trajectories to be determined using only measured values of the directly-observable electromagnetic field. Our gauge-free gyrokinetic theory is general enough to allow for gyroradius-scale fluctuations in both the electric and magnetic field. In addition, we provide gauge-free expressions for the charge and current densities produced by a distribution of gyrocenters, which explicitly include guiding-center and gyrocenter polarization and magnetization effects. This research was supported by the U.S. DOE Contract Nos. DE-SC0014032 (AB) and DE-AC05-06OR23100 (JB).

Collaborative Project: Development of an Isotope-Enabled CESM for Testing Abrupt Climate Changes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Zhengyu

One of the most important validations for a state-of-art Earth System Model (ESM) with respect to climate changes is the simulation of the climate evolution and abrupt climate change events in the Earth’s history of the last 21,000 years. However, one great challenge for model validation is that ESMs usually do not directly simulate geochemical variables that can be compared directly with past proxy records. In this proposal, we have met this challenge by developing the simulation capability of major isotopes in a state-of-art ESM, the Community Earth System Model (CESM), enabling us to make direct model-data comparison by comparingmore » the model directly against proxy climate records. Our isotope-enabled ESM incorporates the capability of simulating key isotopes and geotracers, notably δ 18O, δD, δ 14C, and δ 13C, Nd and Pa/Th. The isotope-enabled ESM have been used to perform some simulations for the last 21000 years. The direct comparison of these simulations with proxy records has shed light on the mechanisms of important climate change events.« less

Tracing the transition of a macro electron shuttle into nonlinear response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Chulki; Prada, Marta; Qin, Hua

We present a study on a macroscopic electron shuttle in the transition from linear to nonlinear response. The shuttle consists of a classical mechanical pendulum situated between two capacitor plates. The metallic pendulum enables mechanical transfer of electrons between the plates, hence allowing to directly trace electron shuttling in the time domain. By applying a high voltage to the plates, we drive the system into a controlled nonlinear response, where we observe period doubling.

Atomic-Monolayer MoS2 Band-to-Band Tunneling Field-Effect Transistor.

PubMed

Lan, Yann-Wen; Torres, Carlos M; Tsai, Shin-Hung; Zhu, Xiaodan; Shi, Yumeng; Li, Ming-Yang; Li, Lain-Jong; Yeh, Wen-Kuan; Wang, Kang L

2016-11-01

The experimental observation of band-to-band tunneling in novel tunneling field-effect transistors utilizing a monolayer of MoS 2 as the conducting channel is demonstrated. Our results indicate that the strong gate-coupling efficiency enabled by two-dimensional materials, such as monolayer MoS 2 , results in the direct manifestation of a band-to-band tunneling current and an ambipolar transport. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Observing Exoplanets with the James Webb Space Telescope

NASA Technical Reports Server (NTRS)

Clampin Mark

2011-01-01

The search for exoplanets and characterization of their properties has seen increasing success over the last few years. In excess of 500 exoplanets are known and Kepler has approx. 1000 additional candidates. Recently, progress has been made in direct imaging planets, both from the ground and in space. This presentation will discuss the history and current state of technology used for such discoveries, and highlight the new capabilities that will be enabled by the James Webb Space Telescope.

Nanophotonic Atomic Force Microscope Transducers Enable Chemical Composition and Thermal Conductivity Measurements at the Nanoscale [Nanophotonic AFM Transducers Enable Chemical Composition and Thermal Conductivity Measurements at the Nanoscale

DOE PAGES

Chae, Jungseok; An, Sangmin; Ramer, Georg; ...

2017-08-03

The atomic force microscope (AFM) offers a rich observation window on the nanoscale, yet many dynamic phenomena are too fast and too weak for direct AFM detection. Integrated cavity-optomechanics is revolutionizing micromechanical sensing; however, it has not yet impacted AFM. Here, we make a groundbreaking advance by fabricating picogram-scale probes integrated with photonic resonators to realize functional AFM detection that achieve high temporal resolution (<10 ns) and picometer vertical displacement uncertainty simultaneously. The ability to capture fast events with high precision is leveraged to measure the thermal conductivity (η), for the first time, concurrently with chemical composition at the nanoscalemore » in photothermal induced resonance experiments. The intrinsic η of metal–organic-framework individual microcrystals, not measurable by macroscale techniques, is obtained with a small measurement uncertainty (8%). The improved sensitivity (50×) increases the measurement throughput 2500-fold and enables chemical composition measurement of molecular monolayer-thin samples. In conclusion, our paradigm-shifting photonic readout for small probes breaks the common trade-off between AFM measurement precision and ability to capture transient events, thus transforming the ability to observe nanoscale dynamics in materials.« less

Nanophotonic Atomic Force Microscope Transducers Enable Chemical Composition and Thermal Conductivity Measurements at the Nanoscale [Nanophotonic AFM Transducers Enable Chemical Composition and Thermal Conductivity Measurements at the Nanoscale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chae, Jungseok; An, Sangmin; Ramer, Georg

The atomic force microscope (AFM) offers a rich observation window on the nanoscale, yet many dynamic phenomena are too fast and too weak for direct AFM detection. Integrated cavity-optomechanics is revolutionizing micromechanical sensing; however, it has not yet impacted AFM. Here, we make a groundbreaking advance by fabricating picogram-scale probes integrated with photonic resonators to realize functional AFM detection that achieve high temporal resolution (<10 ns) and picometer vertical displacement uncertainty simultaneously. The ability to capture fast events with high precision is leveraged to measure the thermal conductivity (η), for the first time, concurrently with chemical composition at the nanoscalemore » in photothermal induced resonance experiments. The intrinsic η of metal–organic-framework individual microcrystals, not measurable by macroscale techniques, is obtained with a small measurement uncertainty (8%). The improved sensitivity (50×) increases the measurement throughput 2500-fold and enables chemical composition measurement of molecular monolayer-thin samples. In conclusion, our paradigm-shifting photonic readout for small probes breaks the common trade-off between AFM measurement precision and ability to capture transient events, thus transforming the ability to observe nanoscale dynamics in materials.« less

Autonomy enables new science missions

NASA Astrophysics Data System (ADS)

Doyle, Richard J.; Gor, Victoria; Man, Guy K.; Stolorz, Paul E.; Chapman, Clark; Merline, William J.; Stern, Alan

1997-01-01

The challenge of space flight in NASA's future is to enable smaller, more frequent and intensive space exploration at much lower total cost without substantially decreasing mission reliability, capability, or the scientific return on investment. The most effective way to achieve this goal is to build intelligent capabilities into the spacecraft themselves. Our technological vision for meeting the challenge of returning quality science through limited communication bandwidth will actually put scientists in a more direct link with the spacecraft than they have enjoyed to date. Technologies such as pattern recognition and machine learning can place a part of the scientist's awareness onboard the spacecraft to prioritize downlink or to autonomously trigger time-critical follow-up observations-particularly important in flyby missions-without ground interaction. Onboard knowledge discovery methods can be used to include candidate discoveries in each downlink for scientists' scrutiny. Such capabilities will allow scientists to quickly reprioritize missions in a much more intimate and efficient manner than is possible today. Ultimately, new classes of exploration missions will be enabled.

Sensors in the Stream: The High-Frequency Wave of the Present.

PubMed

Rode, Michael; Wade, Andrew J; Cohen, Matthew J; Hensley, Robert T; Bowes, Michael J; Kirchner, James W; Arhonditsis, George B; Jordan, Phil; Kronvang, Brian; Halliday, Sarah J; Skeffington, Richard A; Rozemeijer, Joachim C; Aubert, Alice H; Rinke, Karsten; Jomaa, Seifeddine

2016-10-04

New scientific understanding is catalyzed by novel technologies that enhance measurement precision, resolution or type, and that provide new tools to test and develop theory. Over the last 50 years, technology has transformed the hydrologic sciences by enabling direct measurements of watershed fluxes (evapotranspiration, streamflow) at time scales and spatial extents aligned with variation in physical drivers. High frequency water quality measurements, increasingly obtained by in situ water quality sensors, are extending that transformation. Widely available sensors for some physical (temperature) and chemical (conductivity, dissolved oxygen) attributes have become integral to aquatic science, and emerging sensors for nutrients, dissolved CO 2 , turbidity, algal pigments, and dissolved organic matter are now enabling observations of watersheds and streams at time scales commensurate with their fundamental hydrological, energetic, elemental, and biological drivers. Here we synthesize insights from emerging technologies across a suite of applications, and envision future advances, enabled by sensors, in our ability to understand, predict, and restore watershed and stream systems.

Directly Observing Micelle Fusion and Growth in Solution by Liquid-Cell Transmission Electron Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parent, Lucas R.; Bakalis, Evangelos; Ramírez-Hernández, Abelardo

Amphiphilic small molecules and polymers form commonplace nanoscale macromolecular compartments and bilayers, and as such are truly essential components in all cells and in many cellular processes. The nature of these architectures, including their formation, phase changes, and stimuli-response behaviors, is necessary for the most basic functions of life, and over the past half-century, these natural micellar structures have inspired a vast diversity of industrial products, from biomedicines to detergents, lubricants, and coatings. The importance of these materials and their ubiquity have made them the subject of intense investigation regarding their nanoscale dynamics with increasing interest in obtaining sufficient temporalmore » and spatial resolution to directly observe nanoscale processes. However, the vast majority of experimental methods involve either bulk-averaging techniques including light, neutron, and X-ray scattering, or are static in nature including even the most advanced cryogenic transmission electron microscopy techniques. Here, we employ in situ liquid-cell transmission electron microscopy (LCTEM) to directly observe the evolution of individual amphiphilic block copolymer micellar nanoparticles in solution, in real time with nanometer spatial resolution. These observations, made on a proof-of-concept bioconjugate polymer amphiphile, revealed growth and evolution occurring by unimer addition processes and by particle-particle collision-and-fusion events. The experimental approach, combining direct LCTEM observation, quantitative analysis of LCTEM data, and correlated in silico simulations, provides a unique view of solvated soft matter nanoassemblies as they morph and evolve in time and space, enabling us to capture these phenomena in solution.« less

Polymer relaxation and stretching dynamics in semi-dilute DNA solutions: a single molecule study

NASA Astrophysics Data System (ADS)

Hsiao, Kai-Wen; Brockman, Christopher; Schroeder, Charles

2015-03-01

In this work, we study polymer relaxation and stretching dynamics in semi-dilute DNA solutions using single molecule techniques. Using this approach, we uncover a unique scaling relation for longest polymer relaxation time that falls in the crossover regime described by semi-flexible polymer solutions, which is distinct from truly flexible polymer chains. In addition, we performed a series of step-strain experiments on single polymers in semi-dilute solutions in planar extensional flow using an automated microfluidic trap. In this way, we are able to precisely control the flow strength and the amount of strain applied to single polymer chains, thereby enabling direct observation of the full stretching and relaxation process in semi-dilute solutions during transient start-up and flow cessation. Interestingly, we observe polymer individualism in the conformation of single chains in semi-dilute solutions, which to our knowledge has not yet been observed. In addition, we observe the relaxation data can be explained by a multi-exponential decay process after flow cessation in semi-dilute solutions. Overall, our work reports key advance in non-dilute polymer systems from a molecular perspective via direct observation of dynamics in strong flows. DOW fellowship.

Selective molecular annealing: in situ small angle X-ray scattering study of microwave-assisted annealing of block copolymers.

PubMed

Toolan, Daniel T W; Adlington, Kevin; Isakova, Anna; Kalamiotis, Alexis; Mokarian-Tabari, Parvaneh; Dimitrakis, Georgios; Dodds, Christopher; Arnold, Thomas; Terrill, Nick J; Bras, Wim; Hermida Merino, Daniel; Topham, Paul D; Irvine, Derek J; Howse, Jonathan R

2017-08-09

Microwave annealing has emerged as an alternative to traditional thermal annealing approaches for optimising block copolymer self-assembly. A novel sample environment enabling small angle X-ray scattering to be performed in situ during microwave annealing is demonstrated, which has enabled, for the first time, the direct study of the effects of microwave annealing upon the self-assembly behavior of a model, commercial triblock copolymer system [polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene]. Results show that the block copolymer is a poor microwave absorber, resulting in no change in the block copolymer morphology upon application of microwave energy. The block copolymer species may only indirectly interact with the microwave energy when a small molecule microwave-interactive species [diethylene glycol dibenzoate (DEGDB)] is incorporated directly into the polymer matrix. Then significant morphological development is observed at DEGDB loadings ≥6 wt%. Through spatial localisation of the microwave-interactive species, we demonstrate targeted annealing of specific regions of a multi-component system, opening routes for the development of "smart" manufacturing methodologies.

Field-based Information Technology in Geology Education: GeoPads

NASA Astrophysics Data System (ADS)

Knoop, P. A.; van der Pluijm, B.

2004-12-01

During the past two summers, we have successfully incorporated a field-based information technology component into our senior-level, field geology course (GS-440) at the University of Michigan's Camp Davis Geology Field Station, near Jackson, WY. Using GeoPads -- rugged TabletPCs equipped with electronic notebook software, GIS, GPS, and wireless networking -- we have significantly enhanced our field mapping exercises and field trips. While fully retaining the traditional approaches and advantages of field instruction, GeoPads offer important benefits in the development of students' spatial reasoning skills. GeoPads enable students to record observations and directly create geologic maps in the field, using a combination of an electronic field notebook (Microsoft OneNote) tightly integrated with pen-enabled GIS software (ArcGIS-ArcMap). Specifically, this arrangement permits students to analyze and manipulate their data in multiple contexts and representations -- while still in the field -- using both traditional 2-D map views, as well as richer 3-D contexts. Such enhancements provide students with powerful exploratory tools that aid the development of spatial reasoning skills, allowing more intuitive interactions with 2-D representations of our 3-D world. Additionally, field-based GIS mapping enables better error-detection, through immediate interaction with current observations in the context of both supporting data (e.g., topographic maps, aerial photos, magnetic surveys) and students' ongoing observations. The overall field-based IT approach also provides students with experience using tools that are increasingly relevant to their future academic or professional careers.

X-ray microprobe of orbital alignment in strong-field ionized atoms.

PubMed

Young, L; Arms, D A; Dufresne, E M; Dunford, R W; Ederer, D L; Höhr, C; Kanter, E P; Krässig, B; Landahl, E C; Peterson, E R; Rudati, J; Santra, R; Southworth, S H

2006-08-25

We have developed a synchrotron-based, time-resolved x-ray microprobe to investigate optical strong-field processes at intermediate intensities (10(14) - 10(15) W/cm2). This quantum-state specific probe has enabled the direct observation of orbital alignment in the residual ion produced by strong-field ionization of krypton atoms via resonant, polarized x-ray absorption. We found strong alignment to persist for a period long compared to the spin-orbit coupling time scale (6.2 fs). The observed degree of alignment can be explained by models that incorporate spin-orbit coupling. The methodology is applicable to a wide range of problems.

Online Analysis Enhances Use of NASA Earth Science Data

NASA Technical Reports Server (NTRS)

Acker, James G.; Leptoukh, Gregory

2007-01-01

Giovanni, the Goddard Earth Sciences Data and Information Services Center (GES DISC) Interactive Online Visualization and Analysis Infrastructure, has provided researchers with advanced capabilities to perform data exploration and analysis with observational data from NASA Earth observation satellites. In the past 5-10 years, examining geophysical events and processes with remote-sensing data required a multistep process of data discovery, data acquisition, data management, and ultimately data analysis. Giovanni accelerates this process by enabling basic visualization and analysis directly on the World Wide Web. In the last two years, Giovanni has added new data acquisition functions and expanded analysis options to increase its usefulness to the Earth science research community.

Enzyme catalysis: Evolution made easy

NASA Astrophysics Data System (ADS)

Wee, Eugene J. H.; Trau, Matt

2014-09-01

Directed evolution is a powerful tool for the development of improved enzyme catalysts. Now, a method that enables an enzyme, its encoding DNA and a fluorescent reaction product to be encapsulated in a gel bead enables the application of directed evolution in an ultra-high-throughput format.

Lock-in thermography approach for imaging the efficiency of light emitters and optical coolers

NASA Astrophysics Data System (ADS)

Radevici, Ivan; Tiira, Jonna; Oksanen, Jani

2017-02-01

Developing optical cooling technologies requires access to reliable efficiency measurement techniques and ability to detect spatial variations in the efficiency and light emission of the devices. We investigate the possibility to combine the calorimetric efficiency measurement principles with lock-in thermography (LIT) and conventional luminescence microscopy to enable spatially resolved measurement of the efficiency, current spreading and local device heating of double diode structures (DDS) serving as test vessels for developing thermophotonic cooling devices. Our approach enables spatially resolved characterization and localization of the losses of the double diode structures as well as other light emitting semiconductor devices. In particular, the approach may allow directly observing effects like current crowding and surface recombination on the light emission and heating of the DDS devices.

Fermi-LAT Observations of the LIGO Event GW150914

DOE PAGES

Ackermann, M.; Ajello, M.; Albert, A.; ...

2016-05-12

The Fermi Large Area Telescope (LAT) has an instantaneous field of view (FoV) covering ~1/5 of the sky and it completes a survey of the entire sky in high-energy gamma-rays every 3 hr. It enables searches for transient phenomena over timescales from milliseconds to years. Among these phenomena could be electromagnetic counterparts to gravitational wave (GW) sources. In this study, we present a detailed study of the LAT observations relevant to Laser Interferometer Gravitational-wave Observatory (LIGO) event GW150914, which is the first direct detection of gravitational waves and has been interpreted as being due to the coalescence of two stellar-massmore » black holes. The localization region for GW150914 was outside the LAT FoV at the time of the GW signal. However, as part of routine survey observations, the LAT observed the entire LIGO localization region within ~70 minutes of the trigger and thus enabled a comprehensive search for a γ-ray counterpart to GW150914. Finally, the study of the LAT data presented here did not find any potential counterparts to GW150914, but it did provide limits on the presence of a transient counterpart above 100 MeV on timescales of hours to days over the entire GW150914 localization region.« less

Automated Discovery and Modeling of Sequential Patterns Preceding Events of Interest

NASA Technical Reports Server (NTRS)

Rohloff, Kurt

2010-01-01

The integration of emerging data manipulation technologies has enabled a paradigm shift in practitioners' abilities to understand and anticipate events of interest in complex systems. Example events of interest include outbreaks of socio-political violence in nation-states. Rather than relying on human-centric modeling efforts that are limited by the availability of SMEs, automated data processing technologies has enabled the development of innovative automated complex system modeling and predictive analysis technologies. We introduce one such emerging modeling technology - the sequential pattern methodology. We have applied the sequential pattern methodology to automatically identify patterns of observed behavior that precede outbreaks of socio-political violence such as riots, rebellions and coups in nation-states. The sequential pattern methodology is a groundbreaking approach to automated complex system model discovery because it generates easily interpretable patterns based on direct observations of sampled factor data for a deeper understanding of societal behaviors that is tolerant of observation noise and missing data. The discovered patterns are simple to interpret and mimic human's identifications of observed trends in temporal data. Discovered patterns also provide an automated forecasting ability: we discuss an example of using discovered patterns coupled with a rich data environment to forecast various types of socio-political violence in nation-states.

Fermi-LAT Observations of the LIGO Event GW150914

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Albert, A.; Anderson, B.; Arimoto, M.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.;

The total carbon column observing network.

PubMed

Wunch, Debra; Toon, Geoffrey C; Blavier, Jean-François L; Washenfelder, Rebecca A; Notholt, Justus; Connor, Brian J; Griffith, David W T; Sherlock, Vanessa; Wennberg, Paul O

2011-05-28

A global network of ground-based Fourier transform spectrometers has been founded to remotely measure column abundances of CO(2), CO, CH(4), N(2)O and other molecules that absorb in the near-infrared. These measurements are directly comparable with the near-infrared total column measurements from space-based instruments. With stringent requirements on the instrumentation, acquisition procedures, data processing and calibration, the Total Carbon Column Observing Network (TCCON) achieves an accuracy and precision in total column measurements that is unprecedented for remote-sensing observations (better than 0.25% for CO(2)). This has enabled carbon-cycle science investigations using the TCCON dataset, and allows the TCCON to provide a link between satellite measurements and the extensive ground-based in situ network. © 2011 The Royal Society

Simultaneous observation of chemomechanical coupling of a molecular motor.

PubMed

Nishizaka, Takayuki; Hasimoto, Yuh; Masaike, Tomoko

2011-01-01

F(1)-ATPase is the smallest rotary molecular motor ever found. Unidirectional rotation of the γ-shaft is driven by precisely coordinated sequential ATP hydrolysis reactions in three catalytic sites arranged 120° apart in the cylinder. Single-molecule observation allows us to directly watch the rotation of the shaft using micron-sized plastic beads. Additionally, an advanced version of "total internal reflection fluorescence microscope (TIRFM)" enables us to detect binding and release of energy currency through fluorescently labeled ATP. In this chapter, we describe how to set up the system for simultaneous observation of these two critical events. This specialized optical setup is applicable to a variety of research, not only molecular motors but also other single-molecule topics.

Dark matter spin determination with directional direct detection experiments

NASA Astrophysics Data System (ADS)

Catena, Riccardo; Conrad, Jan; Döring, Christian; Ferella, Alfredo Davide; Krauss, Martin B.

2018-01-01

If dark matter has spin 0, only two WIMP-nucleon interaction operators can arise as leading operators from the nonrelativistic reduction of renormalizable single-mediator models for dark matter-quark interactions. Based on this crucial observation, we show that about 100 signal events at next generation directional detection experiments can be enough to enable a 2 σ rejection of the spin 0 dark matter hypothesis in favor of alternative hypotheses where the dark matter particle has spin 1 /2 or 1. In this context, directional sensitivity is crucial since anisotropy patterns in the sphere of nuclear recoil directions depend on the spin of the dark matter particle. For comparison, about 100 signal events are expected in a CF4 detector operating at a pressure of 30 torr with an exposure of approximately 26,000 cubic-meter-detector days for WIMPs of 100 GeV mass and a WIMP-fluorine scattering cross section of 0.25 pb. Comparable exposures require an array of cubic meter time projection chamber detectors.

Real-time Data Streams from ``e-RemoteCtrl'' to Central VLBI Network Status Monitoring Services Like IVS Live

NASA Astrophysics Data System (ADS)

Neidhardt, Alexander; Collioud, Arnaud

2014-12-01

A central VLBI network status monitoring can be realized by using online status information about current VLBI sessions, real-time, and status data directly from each radio telescope. Such monitoring helps to organize sessions or to get immediate feedback from the active telescopes. Therefore the remote control software for VLBI radio telescopes ``e-RemoteCtrl'' (http://www.econtrol-software.de), which enables remote access as extension to the NASA Field System, realizes real-time data streams to dedicated data centers. The software has direct access to the status information about the current observation (e.g., schedule, scan, source) and the telescope (e.g., current state, temperature, pressure) in real-time. This information are directly sent to ``IVS Live''. ``IVS Live'' (http://ivslive.obs.u-bordeaux1.fr/) is a Web tool that can be used to follow the observing sessions, organized by the International VLBI Service for Geodesy and Astrometry (IVS), navigate through past or upcoming sessions, or search and display specific information about sessions, sources (like VLBI images), and stations, by using an Internet browser.

Phospholipid micelle-based magneto-plasmonic nanoformulation for magnetic field-directed, imaging-guided photo-induced cancer therapy.

PubMed

Ohulchanskyy, Tymish Y; Kopwitthaya, Atcha; Jeon, Mansik; Guo, Moran; Law, Wing-Cheung; Furlani, Edward P; Kim, Chulhong; Prasad, Paras N

2013-11-01

We present a magnetoplasmonic nanoplatform combining gold nanorods (GNR) and iron-oxide nanoparticles within phospholipid-based polymeric nanomicelles (PGRFe). The gold nanorods exhibit plasmon resonance absorbance at near infrared wavelengths to enable photoacoustic imaging and photothermal therapy, while the Fe3O4 nanoparticles enable magnetophoretic control of the nanoformulation. The fabricated nanoformulation can be directed and concentrated by an external magnetic field, which provides enhancement of a photoacoustic signal. Application of an external field also leads to enhanced uptake of the magnetoplasmonic formulation by cancer cells in vitro. Under laser irradiation at the wavelength of the GNR absorption peak, the PGRFe formulation efficiently generates plasmonic nanobubbles within cancer cells, as visualized by confocal microscopy, causing cell destruction. The combined magnetic and plasmonic functionalities of the nanoplatform enable magnetic field-directed, imaging-guided, enhanced photo-induced cancer therapy. In this study, a nano-formulation of gold nanorods and iron oxide nanoparticles is presented using a phospholipid micelle-based delivery system for magnetic field-directed and imaging-guided photo-induced cancer therapy. The gold nanorods enable photoacoustic imaging and photothermal therapy, while the Fe3O4 nanoparticles enable magnetophoretic control of the formulation. This and similar systems could enable more precise and efficient cancer therapy, hopefully in the near future, after additional testing. Copyright © 2013 Elsevier Inc. All rights reserved.

Basolateral Amygdala to Orbitofrontal Cortex Projections Enable Cue-Triggered Reward Expectations.

PubMed

Lichtenberg, Nina T; Pennington, Zachary T; Holley, Sandra M; Greenfield, Venuz Y; Cepeda, Carlos; Levine, Michael S; Wassum, Kate M

2017-08-30

To make an appropriate decision, one must anticipate potential future rewarding events, even when they are not readily observable. These expectations are generated by using observable information (e.g., stimuli or available actions) to retrieve often quite detailed memories of available rewards. The basolateral amygdala (BLA) and orbitofrontal cortex (OFC) are two reciprocally connected key nodes in the circuitry supporting such outcome-guided behaviors. But there is much unknown about the contribution of this circuit to decision making, and almost nothing known about the whether any contribution is via direct, monosynaptic projections, or the direction of information transfer. Therefore, here we used designer receptor-mediated inactivation of OFC→BLA or BLA→OFC projections to evaluate their respective contributions to outcome-guided behaviors in rats. Inactivation of BLA terminals in the OFC, but not OFC terminals in the BLA, disrupted the selective motivating influence of cue-triggered reward representations over reward-seeking decisions as assayed by Pavlovian-to-instrumental transfer. BLA→OFC projections were also required when a cued reward representation was used to modify Pavlovian conditional goal-approach responses according to the reward's current value. These projections were not necessary when actions were guided by reward expectations generated based on learned action-reward contingencies, or when rewards themselves, rather than stored memories, directed action. These data demonstrate that BLA→OFC projections enable the cue-triggered reward expectations that can motivate the execution of specific action plans and allow adaptive conditional responding. SIGNIFICANCE STATEMENT Deficits anticipating potential future rewarding events are associated with many psychiatric diseases. Presently, we know little about the neural circuits supporting such reward expectation. Here we show that basolateral amygdala to orbitofrontal cortex projections are required for expectations of specific available rewards to influence reward seeking and decision making. The necessity of these projections was limited to situations in which expectations were elicited by reward-predictive cues. These projections therefore facilitate adaptive behavior by enabling the orbitofrontal cortex to use environmental stimuli to generate expectations of potential future rewarding events. Copyright © 2017 the authors 0270-6474/17/378374-11$15.00/0.

Basolateral Amygdala to Orbitofrontal Cortex Projections Enable Cue-Triggered Reward Expectations

PubMed Central

Lichtenberg, Nina T.; Pennington, Zachary T.; Holley, Sandra M.; Greenfield, Venuz Y.; Levine, Michael S.

2017-01-01

To make an appropriate decision, one must anticipate potential future rewarding events, even when they are not readily observable. These expectations are generated by using observable information (e.g., stimuli or available actions) to retrieve often quite detailed memories of available rewards. The basolateral amygdala (BLA) and orbitofrontal cortex (OFC) are two reciprocally connected key nodes in the circuitry supporting such outcome-guided behaviors. But there is much unknown about the contribution of this circuit to decision making, and almost nothing known about the whether any contribution is via direct, monosynaptic projections, or the direction of information transfer. Therefore, here we used designer receptor-mediated inactivation of OFC→BLA or BLA→OFC projections to evaluate their respective contributions to outcome-guided behaviors in rats. Inactivation of BLA terminals in the OFC, but not OFC terminals in the BLA, disrupted the selective motivating influence of cue-triggered reward representations over reward-seeking decisions as assayed by Pavlovian-to-instrumental transfer. BLA→OFC projections were also required when a cued reward representation was used to modify Pavlovian conditional goal-approach responses according to the reward's current value. These projections were not necessary when actions were guided by reward expectations generated based on learned action-reward contingencies, or when rewards themselves, rather than stored memories, directed action. These data demonstrate that BLA→OFC projections enable the cue-triggered reward expectations that can motivate the execution of specific action plans and allow adaptive conditional responding. SIGNIFICANCE STATEMENT Deficits anticipating potential future rewarding events are associated with many psychiatric diseases. Presently, we know little about the neural circuits supporting such reward expectation. Here we show that basolateral amygdala to orbitofrontal cortex projections are required for expectations of specific available rewards to influence reward seeking and decision making. The necessity of these projections was limited to situations in which expectations were elicited by reward-predictive cues. These projections therefore facilitate adaptive behavior by enabling the orbitofrontal cortex to use environmental stimuli to generate expectations of potential future rewarding events. PMID:28743727

Home Videophones Improve Direct Observation in Tuberculosis Treatment: A Mixed Methods Evaluation

PubMed Central

Wade, Victoria A.; Karnon, Jonathan; Eliott, Jaklin A.; Hiller, Janet E.

2012-01-01

Background The use of direct observation to monitor tuberculosis treatment is controversial: cost, practical difficulties, and lack of patient acceptability limit effectiveness. Telehealth is a promising alternative delivery method for improving implementation. This study aimed to evaluate the clinical and cost-effectiveness of a telehealth service delivering direct observation, compared to an in-person drive-around service. Methodology/Principal Findings The study was conducted within a community nursing service in South Australia. Telehealth patients received daily video calls at home on a desktop videophone provided by the nursing call center. A retrospective cohort study assessed the effectiveness of the telehealth and traditional forms of observation, defined by the proportion of missed observations recorded in case notes. This data was inputted to a model, estimating the incremental cost-effectiveness ratio (ICER) of telehealth. Semi-structured interviews were conducted with current patients, community nursing and Chest Clinic staff, concerning service acceptability, usability and sustainability. The percentage of missed observations for the telehealth service was 12.1 (n = 58), compared to 31.1 for the in-person service (n = 70). Most of the difference of 18.9% (95% CI: 12.2 – 25.4) was due to fewer pre-arranged absences. The economic analysis calculated the ICER to be AUD$1.32 (95% CI: $0.51 – $2.26) per extra day of successful observation. The video service used less staff time, and became dominant if implemented on a larger scale and/or with decreased technology costs. Qualitative analysis found enabling factors of flexible timing, high patient acceptance, staff efficiency, and Chest Clinic support. Substantial technical problems were manageable, and improved liaison between the nursing service and Chest Clinic was an unexpected side-benefit. Conclusions/Significance Home video observation is a patient-centered, resource efficient way of delivering direct observation for TB, and is cost-effective when compared with a drive-around service. Future research is recommended to determine applicability and effectiveness in other settings. PMID:23226243

Direct writing of metal nanostructures: lithographic tools for nanoplasmonics research.

PubMed

Leggett, Graham J

2011-03-22

Continued progress in the fast-growing field of nanoplasmonics will require the development of new methods for the fabrication of metal nanostructures. Optical lithography provides a continually expanding tool box. Two-photon processes, as demonstrated by Shukla et al. (doi: 10.1021/nn103015g), enable the fabrication of gold nanostructures encapsulated in dielectric material in a simple, direct process and offer the prospect of three-dimensional fabrication. At higher resolution, scanning probe techniques enable nanoparticle particle placement by localized oxidation, and near-field sintering of nanoparticulate films enables direct writing of nanowires. Direct laser "printing" of single gold nanoparticles offers a remarkable capability for the controlled fabrication of model structures for fundamental studies, particle-by-particle. Optical methods continue to provide a powerful support for research into metamaterials.

Development of a Kalman Filter in the Gauss-Helmert Model for Reliability Analysis in Orientation Determination with Smartphone Sensors

PubMed Central

Ettlinger, Andreas; Neuner, Hans; Burgess, Thomas

2018-01-01

The topic of indoor positioning and indoor navigation by using observations from smartphone sensors is very challenging as the determined trajectories can be subject to significant deviations compared to the route travelled in reality. Especially the calculation of the direction of movement is the critical part of pedestrian positioning approaches such as Pedestrian Dead Reckoning (“PDR”). Due to distinct systematic effects in filtered trajectories, it can be assumed that there are systematic deviations present in the observations from smartphone sensors. This article has two aims: one is to enable the estimation of partial redundancies for each observation as well as for observation groups. Partial redundancies are a measure for the reliability indicating how well systematic deviations can be detected in single observations used in PDR. The second aim is to analyze the behavior of partial redundancy by modifying the stochastic and functional model of the Kalman filter. The equations relating the observations to the orientation are condition equations, which do not exhibit the typical structure of the Gauss-Markov model (“GMM”), wherein the observations are linear and can be formulated as functions of the states. To calculate and analyze the partial redundancy of the observations from smartphone-sensors used in PDR, the system equation and the measurement equation of a Kalman filter as well as the redundancy matrix need to be derived in the Gauss-Helmert model (“GHM”). These derivations are introduced in this article and lead to a novel Kalman filter structure based on condition equations, enabling reliability assessment of each observation. PMID:29385076

Development of a Kalman Filter in the Gauss-Helmert Model for Reliability Analysis in Orientation Determination with Smartphone Sensors.

PubMed

Ettlinger, Andreas; Neuner, Hans; Burgess, Thomas

2018-01-31

The topic of indoor positioning and indoor navigation by using observations from smartphone sensors is very challenging as the determined trajectories can be subject to significant deviations compared to the route travelled in reality. Especially the calculation of the direction of movement is the critical part of pedestrian positioning approaches such as Pedestrian Dead Reckoning ("PDR"). Due to distinct systematic effects in filtered trajectories, it can be assumed that there are systematic deviations present in the observations from smartphone sensors. This article has two aims: one is to enable the estimation of partial redundancies for each observation as well as for observation groups. Partial redundancies are a measure for the reliability indicating how well systematic deviations can be detected in single observations used in PDR. The second aim is to analyze the behavior of partial redundancy by modifying the stochastic and functional model of the Kalman filter. The equations relating the observations to the orientation are condition equations, which do not exhibit the typical structure of the Gauss-Markov model ("GMM"), wherein the observations are linear and can be formulated as functions of the states. To calculate and analyze the partial redundancy of the observations from smartphone-sensors used in PDR, the system equation and the measurement equation of a Kalman filter as well as the redundancy matrix need to be derived in the Gauss-Helmert model ("GHM"). These derivations are introduced in this article and lead to a novel Kalman filter structure based on condition equations, enabling reliability assessment of each observation.

Route Network Construction with Location-Direction-Enabled Photographs

NASA Astrophysics Data System (ADS)

Fujita, Hideyuki; Sagara, Shota; Ohmori, Tadashi; Shintani, Takahiko

2018-05-01

We propose a method for constructing a geometric graph for generating routes that summarize a geographical area and also have visual continuity by using a set of location-direction-enabled photographs. A location- direction-enabled photograph is a photograph that has information about the location (position of the camera at the time of shooting) and the direction (direction of the camera at the time of shooting). Each nodes of the graph corresponds to a location-direction-enabled photograph. The location of each node is the location of the corresponding photograph, and a route on the graph corresponds to a route in the geographic area and a sequence of photographs. The proposed graph is constructed to represent characteristic spots and paths linking the spots, and it is assumed to be a kind of a spatial summarization of the area with the photographs. Therefore, we call the routes on the graph as spatial summary route. Each route on the proposed graph also has a visual continuity, which means that we can understand the spatial relationship among the continuous photographs on the route such as moving forward, backward, turning right, etc. In this study, when the changes in the shooting position and shooting direction satisfied a given threshold, the route was defined to have visual continuity. By presenting the photographs in order along the generated route, information can be presented sequentially, while maintaining visual continuity to a great extent.

Microscopic analysis of filament in air

DTIC Science & Technology

2016-09-13

scroll pump . The laser beam is shown with a red arrow. It is focused with a parabolic mirror inside at the center of the chamber which is the center...supersonic flow of air acts as a wall between our vacuum chamber and atmospheric air. This design enables us to measure the filaments directly as they...are launched in a vacuum chamber. 3 Technical discussion 3.1 Status of filament research Tinny “pits” were observed in mirrors placed in the path of

Double window viewing chamber assembly

NASA Technical Reports Server (NTRS)

Keller, V. W. (Inventor); Owen, R. B. (Inventor); Elkins, B. R. (Inventor); White, W. T. (Inventor)

1986-01-01

A viewing chamber which permits observation of a sample retained therein includes a pair of double window assemblies mounted in opposed openings in the walls thereof so that a light beam can directly enter and exit from the chamber. A flexible mounting arrangement for the outer windows of the window assemblies enables the windows to be brought into proper alignment. An electrical heating arrangement prevents fogging of the outer windows whereas desiccated air in the volume between the outer and inner windows prevents fogging of the latter.

Preparation of a pure molecular quantum gas.

PubMed

Herbig, Jens; Kraemer, Tobias; Mark, Michael; Weber, Tino; Chin, Cheng; Nägerl, Hanns-Christoph; Grimm, Rudolf

2003-09-12

An ultracold molecular quantum gas is created by application of a magnetic field sweep across a Feshbach resonance to a Bose-Einstein condensate of cesium atoms. The ability to separate the molecules from the atoms permits direct imaging of the pure molecular sample. Magnetic levitation enables study of the dynamics of the ensemble on extended time scales. We measured ultralow expansion energies in the range of a few nanokelvin for a sample of 3000 molecules. Our observations are consistent with the presence of a macroscopic molecular matter wave.

Evaluation of the Self-Directed Personal Services Program Operated through Enable.

ERIC Educational Resources Information Center

Walker, Pam; And Others

This report evaluates a self-directed personal service (SDPS) program operated through the larger Enable Program for people with disabilities in Onondaga County, New York. First, it contrasts characteristics of traditional personal assistance services (such as low pay, agency-determined, limited types/levels of support, and program management…

HIGH DIMENSIONAL COVARIANCE MATRIX ESTIMATION IN APPROXIMATE FACTOR MODELS.

PubMed

Fan, Jianqing; Liao, Yuan; Mincheva, Martina

2011-01-01

The variance covariance matrix plays a central role in the inferential theories of high dimensional factor models in finance and economics. Popular regularization methods of directly exploiting sparsity are not directly applicable to many financial problems. Classical methods of estimating the covariance matrices are based on the strict factor models, assuming independent idiosyncratic components. This assumption, however, is restrictive in practical applications. By assuming sparse error covariance matrix, we allow the presence of the cross-sectional correlation even after taking out common factors, and it enables us to combine the merits of both methods. We estimate the sparse covariance using the adaptive thresholding technique as in Cai and Liu (2011), taking into account the fact that direct observations of the idiosyncratic components are unavailable. The impact of high dimensionality on the covariance matrix estimation based on the factor structure is then studied.

Natural abundance 17O DNP NMR provides precise O–H distances and insights into the Brønsted acidity of heterogeneous catalysts

DOE PAGES

Perras, Frederic A.; Wang, Zhuoran; Naik, Pranjali; ...

2017-05-12

Heterogeneous Brønsted acid catalysts are tremendously important in industry, particularly in catalytic cracking processes. Here we show that these Brønsted acid sites can be directly observed at natural abundance by 17O DNP surface-enhanced NMR spectroscopy (SENS). We additionally show that the O–H bond length in these catalysts can be measured with sub-picometer precision, to enable a direct structural gauge of the lability of protons in a given material, which is correlated with the pH of the zero point of charge of the material. As a result, experiments performed on materials impregnated with pyridine also allow for the direct detection ofmore » intermolecular hydrogen bonding interactions through the lengthening of O–H bonds.« less

Natural abundance 17O DNP NMR provides precise O–H distances and insights into the Brønsted acidity of heterogeneous catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perras, Frederic A.; Wang, Zhuoran; Naik, Pranjali

Heterogeneous Brønsted acid catalysts are tremendously important in industry, particularly in catalytic cracking processes. Here we show that these Brønsted acid sites can be directly observed at natural abundance by 17O DNP surface-enhanced NMR spectroscopy (SENS). We additionally show that the O–H bond length in these catalysts can be measured with sub-picometer precision, to enable a direct structural gauge of the lability of protons in a given material, which is correlated with the pH of the zero point of charge of the material. As a result, experiments performed on materials impregnated with pyridine also allow for the direct detection ofmore » intermolecular hydrogen bonding interactions through the lengthening of O–H bonds.« less

Association of Environmental Indicators with Teen Alcohol Use and Problem Behavior: Teens’ Observations vs. Objectively-Measured Indicators

PubMed Central

Byrnes, Hilary F.; Miller, Brenda A.; Morrison, Christopher N.; Wiebe, Douglas J.; Woychik, Marcie; Wiehe, Sarah E.

2017-01-01

Most prior studies use objectively measured data (e.g., census-based indicators) to assess contextual risks. However, teens’ observations might be more important for their risk behavior. Objectives: 1) determine relationships between observed and objective indicators of contextual risks 2) determine relations of observed and objective indicators with teen alcohol use and problem behavior. Teens aged 14–16 (N=170) carried GPS-enabled smartphones for one month, with locations documented. Ecological momentary assessment (EMA) measured teens’ observations via texts regarding risk behaviors and environmental observations. Objective indicators of alcohol outlets and disorganization were spatially joined to EMAs based on teens’ location at the time of the texts. Observed and objective disorganization, and objective indicators of alcohol outlets were related to alcohol use. Observed disorganization was related to problem behavior, while objective indicators were unrelated. Findings suggest the importance of considering teens’ observations of contextual risk for understanding influences on risk behavior and suggest future directions for research and prevention strategies. PMID:28061392

Validation of Mode-S Meteorological Routine Air Report aircraft observations

NASA Astrophysics Data System (ADS)

Strajnar, B.

2012-12-01

The success of mesoscale data assimilation depends on the availability of three-dimensional observations with high spatial and temporal resolution. This paper describes an example of such observations, available through Mode-S air traffic control system composed of ground radar and transponders on board the aircraft. The meteorological information is provided by interrogation of a dedicated meteorological data register, called Meteorological Routine Air Report (MRAR). MRAR provides direct measurements of temperature and wind, but is only returned by a small fraction of aircraft. The quality of Mode-S MRAR data, collected at the Ljubljana Airport, Slovenia, is assessed by its comparison with AMDAR and high-resolution radiosonde data sets, which enable high- and low-level validation, respectively. The need for temporal smoothing of raw Mode-S MRAR data is also studied. The standard deviation of differences between smoothed Mode-S MRAR and AMDAR is 0.35°C for temperature, 0.8 m/s for wind speed and below 10 degrees for wind direction. The differences with respect to radiosondes are larger, with standard deviations of approximately 1.7°C, 3 m/s and 25 degrees for temperature, wind speed and wind direction, respectively. It is concluded that both wind and temperature observations from Mode-S MRAR are accurate and therefore potentially very useful for data assimilation in numerical weather prediction models.

The position of DNA cleavage by TALENs and cell synchronization influences the frequency of gene editing directed by single-stranded oligonucleotides.

PubMed

Rivera-Torres, Natalia; Strouse, Bryan; Bialk, Pawel; Niamat, Rohina A; Kmiec, Eric B

2014-01-01

With recent technological advances that enable DNA cleavage at specific sites in the human genome, it may now be possible to reverse inborn errors, thereby correcting a mutation, at levels that could have an impact in a clinical setting. We have been developing gene editing, using single-stranded DNA oligonucleotides (ssODNs), as a tool to direct site specific single base changes. Successful application of this technique has been demonstrated in many systems ranging from bacteria to human (ES and somatic) cells. While the frequency of gene editing can vary widely, it is often at a level that does not enable clinical application. As such, a number of stimulatory factors such as double-stranded breaks are known to elevate the frequency significantly. The majority of these results have been discovered using a validated HCT116 mammalian cell model system where credible genetic and biochemical readouts are available. Here, we couple TAL-Effector Nucleases (TALENs) that execute specific ds DNA breaks with ssODNs, designed specifically to repair a missense mutation, in an integrated single copy eGFP gene. We find that proximal cleavage, relative to the mutant base, is key for enabling high frequencies of editing. A directionality of correction is also observed with TALEN activity upstream from the target base being more effective in promoting gene editing than activity downstream. We also find that cells progressing through S phase are more amenable to combinatorial gene editing activity. Thus, we identify novel aspects of gene editing that will help in the design of more effective protocols for genome modification and gene therapy in natural genes.

A Neurocomputational Model of Goal-Directed Navigation in Insect-Inspired Artificial Agents

PubMed Central

Goldschmidt, Dennis; Manoonpong, Poramate; Dasgupta, Sakyasingha

2017-01-01

Despite their small size, insect brains are able to produce robust and efficient navigation in complex environments. Specifically in social insects, such as ants and bees, these navigational capabilities are guided by orientation directing vectors generated by a process called path integration. During this process, they integrate compass and odometric cues to estimate their current location as a vector, called the home vector for guiding them back home on a straight path. They further acquire and retrieve path integration-based vector memories globally to the nest or based on visual landmarks. Although existing computational models reproduced similar behaviors, a neurocomputational model of vector navigation including the acquisition of vector representations has not been described before. Here we present a model of neural mechanisms in a modular closed-loop control—enabling vector navigation in artificial agents. The model consists of a path integration mechanism, reward-modulated global learning, random search, and action selection. The path integration mechanism integrates compass and odometric cues to compute a vectorial representation of the agent's current location as neural activity patterns in circular arrays. A reward-modulated learning rule enables the acquisition of vector memories by associating the local food reward with the path integration state. A motor output is computed based on the combination of vector memories and random exploration. In simulation, we show that the neural mechanisms enable robust homing and localization, even in the presence of external sensory noise. The proposed learning rules lead to goal-directed navigation and route formation performed under realistic conditions. Consequently, we provide a novel approach for vector learning and navigation in a simulated, situated agent linking behavioral observations to their possible underlying neural substrates. PMID:28446872

A Neurocomputational Model of Goal-Directed Navigation in Insect-Inspired Artificial Agents.

PubMed

Goldschmidt, Dennis; Manoonpong, Poramate; Dasgupta, Sakyasingha

2017-01-01

Despite their small size, insect brains are able to produce robust and efficient navigation in complex environments. Specifically in social insects, such as ants and bees, these navigational capabilities are guided by orientation directing vectors generated by a process called path integration. During this process, they integrate compass and odometric cues to estimate their current location as a vector, called the home vector for guiding them back home on a straight path. They further acquire and retrieve path integration-based vector memories globally to the nest or based on visual landmarks. Although existing computational models reproduced similar behaviors, a neurocomputational model of vector navigation including the acquisition of vector representations has not been described before. Here we present a model of neural mechanisms in a modular closed-loop control-enabling vector navigation in artificial agents. The model consists of a path integration mechanism, reward-modulated global learning, random search, and action selection. The path integration mechanism integrates compass and odometric cues to compute a vectorial representation of the agent's current location as neural activity patterns in circular arrays. A reward-modulated learning rule enables the acquisition of vector memories by associating the local food reward with the path integration state. A motor output is computed based on the combination of vector memories and random exploration. In simulation, we show that the neural mechanisms enable robust homing and localization, even in the presence of external sensory noise. The proposed learning rules lead to goal-directed navigation and route formation performed under realistic conditions. Consequently, we provide a novel approach for vector learning and navigation in a simulated, situated agent linking behavioral observations to their possible underlying neural substrates.

Using Enabling Technologies to Facilitate the Comparison of Satellite Observations with the Model Forecasts for Hurricane Study

NASA Astrophysics Data System (ADS)

Li, P.; Knosp, B.; Hristova-Veleva, S. M.; Niamsuwan, N.; Johnson, M. P.; Shen, T. P. J.; Tanelli, S.; Turk, J.; Vu, Q. A.

2014-12-01

Due to their complexity and volume, the satellite data are underutilized in today's hurricane research and operations. To better utilize these data, we developed the JPL Tropical Cyclone Information System (TCIS) - an Interactive Data Portal providing fusion between Near-Real-Time satellite observations and model forecasts to facilitate model evaluation and improvement. We have collected satellite observations and model forecasts in the Atlantic Basin and the East Pacific for the hurricane seasons since 2010 and supported the NASA Airborne Campaigns for Hurricane Study such as the Genesis and Rapid Intensification Processes (GRIP) in 2010 and the Hurricane and Severe Storm Sentinel (HS3) from 2012 to 2014. To enable the direct inter-comparisons of the satellite observations and the model forecasts, the TCIS was integrated with the NASA Earth Observing System Simulator Suite (NEOS3) to produce synthetic observations (e.g. simulated passive microwave brightness temperatures) from a number of operational hurricane forecast models (HWRF and GFS). An automated process was developed to trigger NEOS3 simulations via web services given the location and time of satellite observations, monitor the progress of the NEOS3 simulations, display the synthetic observation and ingest them into the TCIS database when they are done. In addition, three analysis tools, the joint PDF analysis of the brightness temperatures, ARCHER for finding the storm-center and the storm organization and the Wave Number Analysis tool for storm asymmetry and morphology analysis were integrated into TCIS to provide statistical and structural analysis on both observed and synthetic data. Interactive tools were built in the TCIS visualization system to allow the spatial and temporal selections of the datasets, the invocation of the tools with user specified parameters, and the display and the delivery of the results. In this presentation, we will describe the key enabling technologies behind the design of the TCIS interactive data portal and analysis tools, including the spatial database technology for the representation and query of the level 2 satellite data, the automatic process flow using web services, the interactive user interface using the Google Earth API, and a common and expandable Python wrapper to invoke the analysis tools.

Clusters, voids and reconstructions of the cosmic web

NASA Astrophysics Data System (ADS)

Bos, E. G. Patrick

2016-12-01

The Universe is filled for 95% with dark matter and energy that we cannot see. Of the remaining 5% normal matter we can only see a small part. However, if we want to study the Universe as a whole, we will have to get to know it for 100%. We have to uncover indirectly where dark matter is hiding and what is the nature of dark energy. In this thesis we explore two such methods. The first part describes how we can use the large empty regions between galaxies, "voids", to learn more about dark energy. We converted our theoretical simulations to a model of real observations of galaxies. In this model, we perform the same measurements as we would in real observations. This way, we show that it is indeed possible to unravel the nature of dark energy. The second part is based on our computer code: BARCODE. It unites two models: a physical model of the formation of the Cosmic Web, and a description of the observational effects of (clusters of) galaxies, in particular the effect of redshift on distance measurements. It allows us to back-trace our observations to the primordial conditions. These enable us to trace all (dark) matter, also that which we did not directly observe. The result is a reconstruction of the complete Cosmic Web. In these, we studied "filaments". These objects have not yet been extensively studied. BARCODE will enable further study, e.g. by using it to find observable filaments.

Direct imaging and spectroscopy of terrestrial planets with JWST and a starsahde

NASA Astrophysics Data System (ADS)

Soummer, R.; Valenti, J.; Brown, R. A.; Seager, S.; Tumlinson, J.; Cash, W.; Jordan, I.; Postman, M.; Mountain, M.; Glassman, T.; Pueyo, L.; Roberge, A.; NWP Team

2010-10-01

We present a study for using a starshade with the James Webb Space Telescope (JWST). This concept would enable imaging and spectroscopy of a planet similar to the Earth, the study of its habitability, and the search for signs of alien life. JWST was not specifically designed to observe with a starshade, but its instrumentation and its great sensitivity make it capable of achieving major results in the study of terrestrial-mass exoplanets. However, there are some challenges for the starshade designs mainly due to the very large wavelength sensitivity of the HgCdTe detectors. We discuss the combination of a starshade with internal filters in NIRCam and NIRSpec to optimize both science return and starshade performance. We discuss a possible filter upgrade to enable feasible observations of Earth-like planets and in particular spectroscopic characterization in the near infrared. The new filter would not affect NIRSpec's scientific performance nor its operations, but it would dramatically reduce the risk of adding a starshade to JWST in the future and enhance the performance of any starshade that is built.

Soft X-ray and cathodoluminescence measurement, optimisation and analysis at liquid nitrogen temperatures

NASA Astrophysics Data System (ADS)

MacRae, C. M.; Wilson, N. C.; Torpy, A.; Delle Piane, C.

2018-01-01

Advances in field emission gun electron microprobes have led to significant gains in the beam power density and when analysis at high resolution is required then low voltages are often selected. The resulting beam power can lead to damage and this can be minimised by cooling the sample down to cryogenic temperatures allowing sub-micrometre imaging using a variety of spectrometers. Recent advances in soft X-ray emission spectrometers (SXES) offer a spectral tool to measure both chemistry and bonding and when combined with spectral cathodoluminescence the complementary techniques enable new knowledge to be gained from both mineral and materials. Magnesium and aluminium metals have been examined at both room and liquid nitrogen temperatures by SXES and the L-emission Fermi-edge has been observed to sharpen at the lower temperatures directly confirming thermal broadening of the X-ray spectra. Gains in emission intensity and resolution have been observed in cathodoluminescence for liquid nitrogen cooled quartz grains compared to ambient temperature quartz. This has enabled subtle growth features at quartz to quartz-cement boundaries to be imaged for the first time.

Remote Acoustic Imaging of Geosynchronous Satellites

NASA Astrophysics Data System (ADS)

Watson, Z.; Hart, M.

Identification and characterization of orbiting objects that are not spatially resolved are challenging problems for traditional remote sensing methods. Hyper temporal imaging, enabled by fast, low-noise electro-optical detectors is a new sensing modality which may allow the direct detection of acoustic resonances on satellites enabling a new regime of signature and state detection. Detectable signatures may be caused by the oscillations of solar panels, high-gain antennae, or other on-board subsystems driven by thermal gradients, fluctuations in solar radiation pressure, worn reaction wheels, or orbit maneuvers. Herein we present the first hyper-temporal observations of geosynchronous satellites. Data were collected at the Kuiper 1.54-meter telescope in Arizona using an experimental dual-channel imaging instrument that simultaneously measures light in two orthogonally polarized beams at sampling rates extending up to 1 kHz. In these observations, we see evidence of acoustic resonances in the polarization state of satellites. The technique is expected to support object identification and characterization of on-board components and to act as a discriminant between active satellites, debris, and passive bodies.

Observation and Uses of Position-Space Bloch Oscillations in an Ultracold Gas.

PubMed

Geiger, Zachary A; Fujiwara, Kurt M; Singh, Kevin; Senaratne, Ruwan; Rajagopal, Shankari V; Lipatov, Mikhail; Shimasaki, Toshihiko; Driben, Rodislav; Konotop, Vladimir V; Meier, Torsten; Weld, David M

2018-05-25

We report the observation and characterization of position-space Bloch oscillations using cold atoms in a tilted optical lattice. While momentum-space Bloch oscillations are a common feature of optical lattice experiments, the real-space center-of-mass dynamics are typically unresolvable. In a regime of rapid tunneling and low force, we observe real-space Bloch oscillation amplitudes of hundreds of lattice sites, in both ground and excited bands. We demonstrate two unique capabilities enabled by tracking of Bloch dynamics in position space: measurement of the full position-momentum phase-space evolution during a Bloch cycle, and direct imaging of the lattice band structure. These techniques, along with the ability to exert long-distance coherent control of quantum gases without modulation, may open up new possibilities for quantum control and metrology.

Chandra Pilot Survey of Extrasolar Planet Candidates

NASA Astrophysics Data System (ADS)

Tsuboi, Yohko

2012-09-01

We propose to detect planetary-mass companion around young nearby stars by X-ray direct imaging observations with Chandra. Our goals are to determine I. if the X-ray band can be a new probe to the exo-planet search, and II. if a planet emit detectable X-rays with a magnetic origin at a young age. This should be a challenging observation but a brand-new discovery space unique to Chandra. The abundant population of YSOs in the same field of view will enable us to obtain complete X-ray catalogues of YSOs with all categories of masses. We will also execute simultaneous deep NIR observations with IRSF/SIRIUS and Nishiharima 2m telescope to search for the other X-ray-emitting very low-mass objects near our aiming planet candidates.

Laboratory detection and millimeter spectrum of the MgCCH radical

NASA Technical Reports Server (NTRS)

Anderson, M. A.; Ziurys, L. M.

1995-01-01

The pure rotational spectrum of the magnesium monoacetylide radical, MgCCH, has been recorded in the laboratory using millimeter/sub-mm direct absorption spectroscopy. These measurements constitute the first time this molecule has been observed in the laboratory by any spectroscopic method. Seventeen rotational transitions were observed in the frequency range 210-370 GHz for MgCCH, which appears to be a linear molecule with a (sup 2)Sigma ground electronic state. Rotational and fine structure constants were determined for this radical from a nonlinear least squares fit to the data. The rotational rest frequencies measured here will enable astronomical observations to be carried out for MgCCH towards IRC +10216, where the magnesium compounds MgCN and MgNC, as well as many acetylide species, are present.

Observation and Uses of Position-Space Bloch Oscillations in an Ultracold Gas

NASA Astrophysics Data System (ADS)

Geiger, Zachary A.; Fujiwara, Kurt M.; Singh, Kevin; Senaratne, Ruwan; Rajagopal, Shankari V.; Lipatov, Mikhail; Shimasaki, Toshihiko; Driben, Rodislav; Konotop, Vladimir V.; Meier, Torsten; Weld, David M.

2018-05-01

We report the observation and characterization of position-space Bloch oscillations using cold atoms in a tilted optical lattice. While momentum-space Bloch oscillations are a common feature of optical lattice experiments, the real-space center-of-mass dynamics are typically unresolvable. In a regime of rapid tunneling and low force, we observe real-space Bloch oscillation amplitudes of hundreds of lattice sites, in both ground and excited bands. We demonstrate two unique capabilities enabled by tracking of Bloch dynamics in position space: measurement of the full position-momentum phase-space evolution during a Bloch cycle, and direct imaging of the lattice band structure. These techniques, along with the ability to exert long-distance coherent control of quantum gases without modulation, may open up new possibilities for quantum control and metrology.

The Lanchester square-law model extended to a (2,2) conflict

NASA Astrophysics Data System (ADS)

Colegrave, R. K.; Hyde, J. M.

1993-01-01

A natural extension of the Lanchester (1,1) square-law model is the (M,N) linear model in which M forces oppose N forces with constant attrition rates. The (2,2) model is treated from both direct and inverse viewpoints. The inverse problem means that the model is to be fitted to a minimum number of observed force levels, i.e. the attrition rates are to be found from the initial force levels together with the levels observed at two subsequent times. An approach based on Hamiltonian dynamics has enabled the authors to derive a procedure for solving the inverse problem, which is readily computerized. Conflicts in which participants unexpectedly rally or weaken must be excluded.

Quantifying Soiling Loss Directly From PV Yield

DOE PAGES

Deceglie, Michael G.; Micheli, Leonardo; Muller, Matthew

2018-01-23

Soiling of photovoltaic (PV) panels is typically quantified through the use of specialized sensors. Here, we describe and validate a method for estimating soiling loss experienced by PV systems directly from system yield without the need for precipitation data. The method, termed the stochastic rate and recovery (SRR) method, automatically detects soiling intervals in a dataset, then stochastically generates a sample of possible soiling profiles based on the observed characteristics of each interval. In this paper, we describe the method, validate it against soiling station measurements, and compare it with other PV-yield-based soiling estimation methods. The broader application of themore » SRR method will enable the fleet scale assessment of soiling loss to facilitate mitigation planning and risk assessment.« less

A dielectric model of self-assembled monolayer interfaces by capacitive spectroscopy.

PubMed

Góes, Márcio S; Rahman, Habibur; Ryall, Joshua; Davis, Jason J; Bueno, Paulo R

2012-06-26

The presence of self-assembled monolayers at an electrode introduces capacitance and resistance contributions that can profoundly affect subsequently observed electronic characteristics. Despite the impact of this on any voltammetry, these contributions are not directly resolvable with any clarity by standard electrochemical means. A capacitive analysis of such interfaces (by capacitance spectroscopy), introduced here, enables a clean mapping of these features and additionally presents a means of studying layer polarizability and Cole-Cole relaxation effects. The resolved resistive term contributes directly to an intrinsic monolayer uncompensated resistance that has a linear dependence on the layer thickness. The dielectric model proposed is fully aligned with the classic Helmholtz plate capacitor model and additionally explains the inherently associated resistive features of molecular films.

Quantifying Soiling Loss Directly From PV Yield

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deceglie, Michael G.; Micheli, Leonardo; Muller, Matthew

Soiling of photovoltaic (PV) panels is typically quantified through the use of specialized sensors. Here, we describe and validate a method for estimating soiling loss experienced by PV systems directly from system yield without the need for precipitation data. The method, termed the stochastic rate and recovery (SRR) method, automatically detects soiling intervals in a dataset, then stochastically generates a sample of possible soiling profiles based on the observed characteristics of each interval. In this paper, we describe the method, validate it against soiling station measurements, and compare it with other PV-yield-based soiling estimation methods. The broader application of themore » SRR method will enable the fleet scale assessment of soiling loss to facilitate mitigation planning and risk assessment.« less

The physical origin of the X-ray emission from SN 1987A

NASA Astrophysics Data System (ADS)

Miceli, M.; Orlando, S.; Petruk, O.

2017-10-01

We revisit the spectral analysis of the set of archive XMM-Newton observations of SN 1987A through our 3-D hydrodynamic model describing the whole evolution from the onset of the supernova to the full remnant development. For the first time the spectral analysis accounts for the single observations and for the evolution of the system self-consistently. We adopt a forward modeling approach which allows us to directly synthesize, from the model, X-ray spectra and images in different energy bands. We fold the synthetic observables through the XMM-Newton instrumental response and directly compare models and actual data. We find that our simulation provides an excellent fit to the data, by reproducing simultaneously X-ray fluxes, spectral features, and morphology of SN 1987A at all evolutionary stages. Our analysis enables us to obtain a deep insight on the physical origin of the observed multi-thermal emission, by revealing the contribution of shocked surrounding medium, dense clumps of the circumstellar ring, and ejecta to the total emission. We finally provide predictions for future observations (to be performed with XMM-Newton in the next future and with the forthcoming Athena X-ray telescope in approximately 10 years), showing the growing contribution of the ejecta X-ray emission.

Evaluation of Cloud Microphysics in JMA-NHM Simulations Using Bin or Bulk Microphysical Schemes through Comparison with Cloud Radar Observations

NASA Technical Reports Server (NTRS)

Iguchi, Takamichi; Nakajima, Teruyuki; Khain, Alexander P.; Saito, Kazuo; Takemura, Toshihiko; Okamoto, Hajime; Nishizawa, Tomoaki; Tao, Wei-Kuo

2012-01-01

Numerical weather prediction (NWP) simulations using the Japan Meteorological Agency NonhydrostaticModel (JMA-NHM) are conducted for three precipitation events observed by shipborne or spaceborneW-band cloud radars. Spectral bin and single-moment bulk cloud microphysics schemes are employed separatelyfor an intercomparative study. A radar product simulator that is compatible with both microphysicsschemes is developed to enable a direct comparison between simulation and observation with respect to theequivalent radar reflectivity factor Ze, Doppler velocity (DV), and path-integrated attenuation (PIA). Ingeneral, the bin model simulation shows better agreement with the observed data than the bulk modelsimulation. The correction of the terminal fall velocities of snowflakes using those of hail further improves theresult of the bin model simulation. The results indicate that there are substantial uncertainties in the masssizeand sizeterminal fall velocity relations of snowflakes or in the calculation of terminal fall velocity of snowaloft. For the bulk microphysics, the overestimation of Ze is observed as a result of a significant predominanceof snow over cloud ice due to substantial deposition growth directly to snow. The DV comparison shows thata correction for the fall velocity of hydrometeors considering a change of particle size should be introducedeven in single-moment bulk cloud microphysics.

Determining the direction of tooth grinding: an in vitro study.

PubMed

ten Berge, F; te Poel, J; Ranjitkar, S; Kaidonis, J A; Lobbezoo, F; Hughes, T E; Townsend, G C

2012-08-01

The analysis of microwear patterns, including scratch types and widths, has enabled reconstruction of the dietary habits and lifestyles of prehistoric and modern humans. The aim of this in vitro study was to determine whether an assessment of microwear features of experimental scratches placed on enamel, perpendicularly to the direction of grinding, could predict the grinding direction. Experimental scratches were placed using a scalpel blade on standardised wear facets that had been prepared by wearing opposing enamel surfaces in an electromechanical tooth wear machine. These control 'baseline' facets (with unworn experimental scratches) were subjected to 50 wear cycles, so that differential microwear could be observed on the leading and trailing edges of the 'final' facets. In Group 1 (n=28), the 'footprint' microwear patterns corresponding to the known grinding direction of specimens in the tooth wear machine were identified. Then, they were used to predict the direction of tooth grinding blindly in the same sample after a 2-week intermission period. To avoid overfitting the predictive model, its sensitivity was also cross-validated in a new sample (Group 2, n=14). A crescent-shaped characteristic observed in most experimental scratches matched the grinding direction on all occasions. The best predictor of the direction of grinding was a combined assessment of the leading edge microwear pattern and the crescent characteristic (82.1% in Group 1 and 92.9% in Group 2). In conclusion, a simple scratch test can determine the direction of tooth grinding with high reliability, although further improvement in sensitivity is desirable. © 2012 Blackwell Publishing Ltd.

Archer fish fast hunting maneuver may be guided by directionally selective retinal ganglion cells.

PubMed

Tsvilling, Vadim; Donchin, Opher; Shamir, Maoz; Segev, Ronen

2012-02-01

Archer fish are known for their unique hunting method, where one fish in a group shoots down an insect with a jet of water while all the other fish are observing the prey's motion. To reap its reward, the archer fish must reach the prey before its competitors. This requires fast computation of the direction of motion of the prey, which enables the fish to initiate a turn towards the prey with an accuracy of 99%, at about 100 ms after the prey is shot. We explored the hypothesis that direction-selective retinal ganglion cells may underlie this rapid processing. We quantified the degree of directional selectivity of ganglion cells in the archer fish retina. The cells could be categorized into three groups: sharply (5%), broadly (37%) and non-tuned (58%) directionally selective cells. To relate the electrophysiological data to the behavioral results we studied a computational model and estimated the time required to accumulate sufficient directional information to match the decision accuracy of the fish. The computational model is based on two direction-selective populations that race against each other until one reaches the threshold and drives the decision. We found that this competition model can account for the observed response time at the required accuracy. Thus, our results are consistent with the hypothesis that the fast response behavior of the archer fish relies on retinal identification of movement direction. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Bio-inspired direct patterning functional nanothin microlines: controllable liquid transfer.

PubMed

Wang, Qianbin; Meng, Qingan; Wang, Pengwei; Liu, Huan; Jiang, Lei

2015-04-28

Developing a general and low-cost strategy that enables direct patterning of microlines with nanometer thickness from versatile liquid-phase functional materials and precise positioning of them on various substrates remains a challenge. Herein, with inspiration from the oriental wisdom to control ink transfer by Chinese brushes, we developed a facile and general writing strategy to directly pattern various functional microlines with homogeneous distribution and nanometer-scale thickness. It is demonstrated that the width and thickness of the microlines could be well-controlled by tuning the writing method, providing guidance for the adaptation of this technique to various systems. It is also shown that various functional liquid-phase materials, such as quantum dots, small molecules, polymers, and suspensions of nanoparticles, could directly write on the substrates with intrinsic physicochemical properties well-preserved. Moreover, this technique enabled direct patterning of liquid-phase materials on certain microdomains, even in multiple layered style, thus a microdomain localized chemical reaction and the patterned surface chemical modification were enabled. This bio-inspired direct writing device will shed light on the template-free printing of various functional micropatterns, as well as the integrated functional microdevices.

Development of the High-Order Decoupled Direct Method in Three Dimensions for Particulate Matter: Enabling Advanced Sensitivity Analysis in Air Quality Models

EPA Science Inventory

The high-order decoupled direct method in three dimensions for particular matter (HDDM-3D/PM) has been implemented in the Community Multiscale Air Quality (CMAQ) model to enable advanced sensitivity analysis. The major effort of this work is to develop high-order DDM sensitivity...

Enabling Self-Directed Computer Use for Individuals with Cerebral Palsy: A Systematic Review of Assistive Devices and Technologies

ERIC Educational Resources Information Center

Davies, T. Claire; Mudge, Suzie; Ameratunga, Shanthi; Stott, N. Susan

2010-01-01

Aim: The purpose of this study was to systematically review published evidence on the development, use, and effectiveness of devices and technologies that enable or enhance self-directed computer access by individuals with cerebral palsy (CP). Methods: Nine electronic databases were searched using keywords "computer", "software", "spastic",…

Direct Characterization of Ultrafast Energy-Time Entangled Photon Pairs.

PubMed

MacLean, Jean-Philippe W; Donohue, John M; Resch, Kevin J

2018-02-02

Energy-time entangled photons are critical in many quantum optical phenomena and have emerged as important elements in quantum information protocols. Entanglement in this degree of freedom often manifests itself on ultrafast time scales, making it very difficult to detect, whether one employs direct or interferometric techniques, as photon-counting detectors have insufficient time resolution. Here, we implement ultrafast photon counters based on nonlinear interactions and strong femtosecond laser pulses to probe energy-time entanglement in this important regime. Using this technique and single-photon spectrometers, we characterize all the spectral and temporal correlations of two entangled photons with femtosecond resolution. This enables the witnessing of energy-time entanglement using uncertainty relations and the direct observation of nonlocal dispersion cancellation on ultrafast time scales. These techniques are essential to understand and control the energy-time degree of freedom of light for ultrafast quantum optics.

HIGH DIMENSIONAL COVARIANCE MATRIX ESTIMATION IN APPROXIMATE FACTOR MODELS

PubMed Central

Fan, Jianqing; Liao, Yuan; Mincheva, Martina

2012-01-01

The variance covariance matrix plays a central role in the inferential theories of high dimensional factor models in finance and economics. Popular regularization methods of directly exploiting sparsity are not directly applicable to many financial problems. Classical methods of estimating the covariance matrices are based on the strict factor models, assuming independent idiosyncratic components. This assumption, however, is restrictive in practical applications. By assuming sparse error covariance matrix, we allow the presence of the cross-sectional correlation even after taking out common factors, and it enables us to combine the merits of both methods. We estimate the sparse covariance using the adaptive thresholding technique as in Cai and Liu (2011), taking into account the fact that direct observations of the idiosyncratic components are unavailable. The impact of high dimensionality on the covariance matrix estimation based on the factor structure is then studied. PMID:22661790

Angular tuning of the magnetic birefringence in rippled cobalt films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arranz, Miguel A., E-mail: MiguelAngel.Arranz@uclm.es; Colino, José M.

We report the measurement of magnetically induced birefringence in rippled Co films. For this purpose, the magneto-optical properties of ion beam eroded ferromagnetic films were studied using Kerr magnetometry and magnetic birefringence in the transmitted light intensity. Upon sufficient ion sculpting, these ripple surface nanostructures developed a defined uniaxial anisotropy in the in-plane magnetization, finely tuning the magnetic birefringence effect. We have studied its dependence on the relative orientation between the ripple direction and the magnetic field, and found this effect to be dramatically correlated with the capability to neatly distinguish the mechanisms for the in-plane magnetization reversal, i.e., rotationmore » and nucleation. This double refraction corresponds univocally to the two magnetization axes, parallel and perpendicular to the ripples direction. We have also observed that tuned birefringence in stack assemblies of rippled Co films, which enables us to technically manipulate the number and direction of refraction axes.« less

A wireless centrifuge force microscope (CFM) enables multiplexed single-molecule experiments in a commercial centrifuge.

PubMed

Hoang, Tony; Patel, Dhruv S; Halvorsen, Ken

2016-08-01

The centrifuge force microscope (CFM) was recently introduced as a platform for massively parallel single-molecule manipulation and analysis. Here we developed a low-cost and self-contained CFM module that works directly within a commercial centrifuge, greatly improving accessibility and ease of use. Our instrument incorporates research grade video microscopy, a power source, a computer, and wireless transmission capability to simultaneously monitor many individually tethered microspheres. We validated the instrument by performing single-molecule force shearing of short DNA duplexes. For a 7 bp duplex, we observed over 1000 dissociation events due to force dependent shearing from 2 pN to 12 pN with dissociation times in the range of 10-100 s. We extended the measurement to a 10 bp duplex, applying a 12 pN force clamp and directly observing single-molecule dissociation over an 85 min experiment. Our new CFM module facilitates simple and inexpensive experiments that dramatically improve access to single-molecule analysis.

A Direct, Quantitative Connection between Molecular Dynamics Simulations and Vibrational Probe Line Shapes.

PubMed

Xu, Rosalind J; Blasiak, Bartosz; Cho, Minhaeng; Layfield, Joshua P; Londergan, Casey H

2018-05-17

A quantitative connection between molecular dynamics simulations and vibrational spectroscopy of probe-labeled systems would enable direct translation of experimental data into structural and dynamical information. To constitute this connection, all-atom molecular dynamics (MD) simulations were performed for two SCN probe sites (solvent-exposed and buried) in a calmodulin-target peptide complex. Two frequency calculation approaches with substantial nonelectrostatic components, a quantum mechanics/molecular mechanics (QM/MM)-based technique and a solvatochromic fragment potential (SolEFP) approach, were used to simulate the infrared probe line shapes. While QM/MM results disagreed with experiment, SolEFP results matched experimental frequencies and line shapes and revealed the physical and dynamic bases for the observed spectroscopic behavior. The main determinant of the CN probe frequency is the exchange repulsion between the probe and its local structural neighbors, and there is a clear dynamic explanation for the relatively broad probe line shape observed at the "buried" probe site. This methodology should be widely applicable to vibrational probes in many environments.

Multidomain Skyrmion Lattice State in Cu2OSeO3.

PubMed

Zhang, S L; Bauer, A; Burn, D M; Milde, P; Neuber, E; Eng, L M; Berger, H; Pfleiderer, C; van der Laan, G; Hesjedal, T

2016-05-11

Magnetic skyrmions in chiral magnets are nanoscale, topologically protected magnetization swirls that are promising candidates for spintronics memory carriers. Therefore, observing and manipulating the skyrmion state on the surface level of the materials are of great importance for future applications. Here, we report a controlled way of creating a multidomain skyrmion state near the surface of a Cu2OSeO3 single crystal, observed by soft resonant elastic X-ray scattering. This technique is an ideal tool to probe the magnetic order at the L3 edge of 3d metal compounds giving an average depth sensitivity of ∼50 nm. The single-domain 6-fold-symmetric skyrmion lattice can be broken up into domains, overcoming the propagation directions imposed by the cubic anisotropy by applying the magnetic field in directions deviating from the major cubic axes. Our findings open the door to a new way to manipulate and engineer the skyrmion state locally on the surface or on the level of individual skyrmions, which will enable applications in the future.

The Age of Planet Host κ Andromedae Based on Interferometric Observations

NASA Astrophysics Data System (ADS)

Jones, Jeremy; White, Russel J.; Quinn, Samuel N.; Baines, Ellyn K.; Boyajian, Tabetha S.; Ireland, Michael; CHARA Team

2016-01-01

We present CHARA Array interferometric observations, obtained with the PAVO beam combiner in the optical (~750 nm), of κ Andromedae. This nearby (51.6 pc) B9/A0V star hosts a directly-imaged low mass companion. Observations made at multiple orientations show the star to be oblate (~15%), consistent with its large projected rotational velocity (vsini = 161.6 ± 22.2 km s-1). The interferometric observations, combined with photometry and the vsini are used to constrain an oblate star model of κ And, enabling us to determine its fundamental properties (e.g., average radius, bolometric luminosity, and equatorial velocity). These stellar properties are compared to the predictions of MESA evolution models to determine an age and mass for the star. The best fit model favors a young age for the system (< 100 Myr), which implies that κ And b has a mass around the limit separating planets and brown dwarfs.

Coronal Magnetism and Forward Solarsoft Idl Package

NASA Astrophysics Data System (ADS)

Gibson, S. E.

2014-12-01

The FORWARD suite of Solar Soft IDL codes is a community resource for model-data comparison, with a particular emphasis on analyzing coronal magnetic fields. FORWARD may be used both to synthesize a broad range of coronal observables, and to access and compare to existing data. FORWARD works with numerical model datacubes, interfaces with the web-served Predictive Science Inc MAS simulation datacubes and the Solar Soft IDL Potential Field Source Surface (PFSS) package, and also includes several analytic models (more can be added). It connects to the Virtual Solar Observatory and other web-served observations to download data in a format directly comparable to model predictions. It utilizes the CHIANTI database in modeling UV/EUV lines, and links to the CLE polarimetry synthesis code for forbidden coronal lines. FORWARD enables "forward-fitting" of specific observations, and helps to build intuition into how the physical properties of coronal magnetic structures translate to observable properties.

Using GPS-enabled cell phones to track the travel patterns of adolescents.

PubMed

Wiehe, Sarah E; Carroll, Aaron E; Liu, Gilbert C; Haberkorn, Kelly L; Hoch, Shawn C; Wilson, Jeffery S; Fortenberry, J Dennis

2008-05-21

Few tools exist to directly measure the microsocial and physical environments of adolescents in circumstances where participatory observation is not practical or ethical. Yet measuring these environments is important as they are significantly associated with adolescent health-risk. For example, health-related behaviors such as cigarette smoking often occur in specific places where smoking may be relatively surreptitious. We assessed the feasibility of using GPS-enabled cell phones to track adolescent travel patterns and gather daily diary data. We enrolled 15 adolescent women from a clinic-based setting and asked them to carry the phones for 1 week. We found that these phones can accurately and reliably track participant locations, as well as record diary information on adolescent behaviors. Participants had variable paths extending beyond their immediate neighborhoods, and denied that GPS-tracking influenced their activity. GPS-enabled cell phones offer a feasible and, in many ways, ideal modality of monitoring the location and travel patterns of adolescents. In addition, cell phones allow space- and time-specific interaction, probing, and intervention which significantly extends both research and health promotion beyond a clinical setting. Future studies can employ GPS-enabled cell phones to better understand adolescent environments, how they are associated with health-risk behaviors, and perhaps intervene to change health behavior.

Using GPS-enabled cell phones to track the travel patterns of adolescents

PubMed Central

Wiehe, Sarah E; Carroll, Aaron E; Liu, Gilbert C; Haberkorn, Kelly L; Hoch, Shawn C; Wilson, Jeffery S; Fortenberry, J Dennis

2008-01-01

Background Few tools exist to directly measure the microsocial and physical environments of adolescents in circumstances where participatory observation is not practical or ethical. Yet measuring these environments is important as they are significantly associated with adolescent health-risk. For example, health-related behaviors such as cigarette smoking often occur in specific places where smoking may be relatively surreptitious. Results We assessed the feasibility of using GPS-enabled cell phones to track adolescent travel patterns and gather daily diary data. We enrolled 15 adolescent women from a clinic-based setting and asked them to carry the phones for 1 week. We found that these phones can accurately and reliably track participant locations, as well as record diary information on adolescent behaviors. Participants had variable paths extending beyond their immediate neighborhoods, and denied that GPS-tracking influenced their activity. Conclusion GPS-enabled cell phones offer a feasible and, in many ways, ideal modality of monitoring the location and travel patterns of adolescents. In addition, cell phones allow space- and time-specific interaction, probing, and intervention which significantly extends both research and health promotion beyond a clinical setting. Future studies can employ GPS-enabled cell phones to better understand adolescent environments, how they are associated with health-risk behaviors, and perhaps intervene to change health behavior. PMID:18495025

Observation and excitation of magnetohydrodynamic waves in numerical models of Earth's core

NASA Astrophysics Data System (ADS)

Teed, R.; Hori, K.; Tobias, S.; Jones, C. A.

2017-12-01

Several types of magnetohydrodynamic waves are theorised to operate in Earth's outer core but their detection is limited by the inability to probe the fluid core directly. Secular variation data and periodic changes in Earth's length-of-day provide evidence for the possible existence of waves. Numerical simulations of core dynamics enable us to search directly for waves and determine their properties. With this information it is possible to consider whether they can be the origin of features observed in observational data. We focus on two types of wave identified in our numerical experiments: i) torsional waves and ii) slow magnetic Rossby waves. Our models display periodic, Earth-like torsional waves that travel outwards from the tangent cylinder circumscribing the inner core. We discuss the properties of these waves and their similarites to observational data. Excitation is via a matching of the Alfvén frequency with that of small modes of convection focused at the tangent cylinder. The slow magnetic Rossby waves observed in our simulations show that these waves may account for some geomagnetic westward drifts observed at mid-latitudes. We present analysis showing excitation of waves by the convective instability and we discuss how the detection of these waves could also provide an estimate of the strength of the toroidal component of the magnetic field within the planetary fluid core.

Recent progress on DNA based walkers.

PubMed

Pan, Jing; Li, Feiran; Cha, Tae-Gon; Chen, Haorong; Choi, Jong Hyun

2015-08-01

DNA based synthetic molecular walkers are reminiscent of biological protein motors. They are powered by hybridization with fuel strands, environment induced conformational transitions, and covalent chemistry of oligonucleotides. Recent developments in experimental techniques enable direct observation of individual walkers with high temporal and spatial resolution. The functionalities of state-of-the-art DNA walker systems can thus be analyzed for various applications. Herein we review recent progress on DNA walker principles and characterization methods, and evaluate various aspects of their functions for future applications. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cryo-electron tomography of bacterial viruses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guerrero-Ferreira, Ricardo C.; Wright, Elizabeth R., E-mail: erwrigh@emory.edu

2013-01-05

Bacteriophage particles contain both simple and complex macromolecular assemblages and machines that enable them to regulate the infection process under diverse environmental conditions with a broad range of bacterial hosts. Recent developments in cryo-electron tomography (cryo-ET) make it possible to observe the interactions of bacteriophages with their host cells under native-state conditions at unprecedented resolution and in three-dimensions. This review describes the application of cryo-ET to studies of bacteriophage attachment, genome ejection, assembly and egress. Current topics of investigation and future directions in the field are also discussed.

Torus Breakdown and Homoclinic Chaos in a Glow Discharge Tube

NASA Astrophysics Data System (ADS)

Ginoux, Jean-Marc; Meucci, Riccardo; Euzzor, Stefano

2017-12-01

Starting from historical researches, we used, like Van der Pol and Le Corbeiller, a cubic function for modeling the current-voltage characteristic of a direct current low-pressure plasma discharge tube, i.e. a neon tube. This led us to propose a new four-dimensional autonomous dynamical system allowing to describe the experimentally observed phenomenon. Then, mathematical analysis and detailed numerical investigations of such a fourth-order torus circuit enabled to highlight bifurcation routes from torus breakdown to homoclinic chaos following the Newhouse-Ruelle-Takens scenario.

Progress of Rugby Hohlraum Experiments on Omega

NASA Astrophysics Data System (ADS)

Philippe, Franck; Tassin, Veronique; Casner, Alexis; Gauthier, Pascal; Seytor, Patricia; Monteil, Marie-Christine; Park, Hye-Sook; Robey, Harry; Ross, Steven; Amendt, Peter; Girard, Frederic; Villette, Bruno; Reverdin, Charles; Loiseau, Pascal; Caillaud, Tony; Landoas, Olivier; Li, Chi Kang; Petrasso, Richard; Seguin, Fredrick; Rosenberg, Markus

2011-10-01

The rugby hohlraum concept is predicted to enable better coupling and higher gains in the indirect drive approach to ignition. A collaborative experimental program is currently pursued on OMEGA to test this concept in preparation for future megajoule-scale ignition designs. A direct comparison of gas-filled rugby hohlraums with classical cylinders was recently performed, showing a significant (up to ~40%) observed x-ray drive enhancement and neutron yields that are consistently higher in the rugby case. This work extends and confirms our previous findings in empty rugby hohlraums.

An investigation of hydrogenized amorphous Si structures with Doppler broadening positron annihilation techniques

NASA Astrophysics Data System (ADS)

Petkov, M. P.; Marek, T.; Asoka-Kumar, P.; Lynn, K. G.; Crandall, R. S.; Mahan, A. H.

1998-07-01

In this letter, we examine the feasibility of applying positron annihilation spectroscopy to the study of hydrogenized amorphous silicon (a-Si:H)-based structures produced by chemical vapor deposition techniques. The positron probe, sensitive to open volume formations, is used to characterize neutral and negatively charged silicon dangling bonds, typical for undoped and n-doped a-Si:H, respectively. Using depth profiling along the growth direction a difference was observed in the electronic environment of these defects, which enables their identification in a p-i-n device.

Distributions of Dusty Star Forming Region in Local Starburst Galaxies

NASA Astrophysics Data System (ADS)

Tateuchi, K.; Motohara, K.; Konishi, M.; Takahashi, H.; Kato, N.; Kitagawa, Y.; Yoshii, Y.; Doi, M.; Kohno, K.; Kawara, K.; Tanaka, M.; Miyata, T.; Tanabe, T.; Minezaki, T.; Sako, S.; Morokuma, T.; Tamura, Y.; Aoki, T.; Soyano, T.; Tarusawa, K.; Koshida, S.; Kamizuka, T.; Asano, K.; Uchiyama, M.; Okada, K.

2013-10-01

Since the first light observation of ANIR in June 2009, we have been carrying out a Paα narrow-band imaging survey of nearby luminous infrared galaxies (LIRGs). Because Paα is the strongest hydrogen recombination line in the infrared wavelength ranges, it is a good and direct tracer of dust-enshrouded star forming regions, and enables us to probe the star formation activities in LIRGs. We find that LIRGs have two star-forming modes. The origin of the two modes probably come from differences between merging stage and/or star-forming process.

Multiple-Star System Adaptive Vortex Coronagraphy Using a Liquid Crystal Light Valve

NASA Astrophysics Data System (ADS)

Aleksanyan, Artur; Kravets, Nina; Brasselet, Etienne

2017-05-01

We propose the development of a high-contrast imaging technique enabling the simultaneous and selective nulling of several light sources. This is done by realizing a reconfigurable multiple-vortex phase mask made of a liquid crystal thin film on which local topological features can be addressed electro-optically. The method is illustrated by reporting on a triple-star optical vortex coronagraphy laboratory demonstration, which can be easily extended to higher multiplicity. These results allow considering the direct observation and analysis of worlds with multiple suns and more complex extrasolar planetary systems.

Incorporating variability in honey bee waggle dance decoding improves the mapping of communicated resource locations.

PubMed

Schürch, Roger; Couvillon, Margaret J; Burns, Dominic D R; Tasman, Kiah; Waxman, David; Ratnieks, Francis L W

2013-12-01

Honey bees communicate to nestmates locations of resources, including food, water, tree resin and nest sites, by making waggle dances. Dances are composed of repeated waggle runs, which encode the distance and direction vector from the hive or swarm to the resource. Distance is encoded in the duration of the waggle run, and direction is encoded in the angle of the dancer's body relative to vertical. Glass-walled observation hives enable researchers to observe or video, and decode waggle runs. However, variation in these signals makes it impossible to determine exact locations advertised. We present a Bayesian duration to distance calibration curve using Markov Chain Monte Carlo simulations that allows us to quantify how accurately distance to a food resource can be predicted from waggle run durations within a single dance. An angular calibration shows that angular precision does not change over distance, resulting in spatial scatter proportional to distance. We demonstrate how to combine distance and direction to produce a spatial probability distribution of the resource location advertised by the dance. Finally, we show how to map honey bee foraging and discuss how our approach can be integrated with Geographic Information Systems to better understand honey bee foraging ecology.

Microinverters for employment in connection with photovoltaic modules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lentine, Anthony L.; Nielson, Gregory N.; Okandan, Murat

2015-09-22

Microinverters useable in association with photovoltaic modules are described. A three phase-microinverter receives direct current output generated by a microsystems-enabled photovoltaic cell and converts such direct current output into three-phase alternating current out. The three-phase microinverter is interleaved with other three-phase-microinverters, wherein such microinverters are integrated in a photovoltaic module with the microsystems-enabled photovoltaic cell.

Swimming Back and Forth Using Planar Flagellar Propulsion at Low Reynolds Numbers.

PubMed

Khalil, Islam S M; Tabak, Ahmet Fatih; Hamed, Youssef; Mitwally, Mohamed E; Tawakol, Mohamed; Klingner, Anke; Sitti, Metin

2018-02-01

Peritrichously flagellated Escherichia coli swim back and forth by wrapping their flagella together in a helical bundle. However, other monotrichous bacteria cannot swim back and forth with a single flagellum and planar wave propagation. Quantifying this observation, a magnetically driven soft two-tailed microrobot capable of reversing its swimming direction without making a U-turn trajectory or actively modifying the direction of wave propagation is designed and developed. The microrobot contains magnetic microparticles within the polymer matrix of its head and consists of two collinear, unequal, and opposite ultrathin tails. It is driven and steered using a uniform magnetic field along the direction of motion with a sinusoidally varying orthogonal component. Distinct reversal frequencies that enable selective and independent excitation of the first or the second tail of the microrobot based on their tail length ratio are found. While the first tail provides a propulsive force below one of the reversal frequencies, the second is almost passive, and the net propulsive force achieves flagellated motion along one direction. On the other hand, the second tail achieves flagellated propulsion along the opposite direction above the reversal frequency.

Murai Reaction on Furfural Derivatives Enabled by Removable N,N'-Bidentate Directing Groups.

PubMed

Pezzetta, Cristofer; Veiros, Luis F; Oble, Julie; Poli, Giovanni

2017-06-22

Furfural and related compounds are industrially relevant building blocks obtained from lignocellulosic biomass. To enhance the added value of these renewable resources, a Ru-catalyzed hydrofurylation of alkenes, involving a directed C-H activation at C3 of the furan ring, was developed. A thorough experimental study revealed that a bidentate amino-imine directing group enabled the desired coupling. Removal of the directing group occurred during the purification step, directly releasing the C3-functionalized furfurals. Development of the reaction as well as optimization and scope of the method were described. A mechanism was proposed on the basis of DFT calculations. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Participation of adolescents in the Family Health Strategy from the theoretical-methodological structure of an enabler to participation.

PubMed

Vieira, Roberta Peixoto; Gomes, Sílvia Helena Pereira; Machado, Maria de Fátima Antero Sousa; Bezerra, Italla Maria Pinheiro; Machado, Caroline Antero

2014-01-01

to evaluate the participation of adolescents in the Family Health Strategy, from the theoretical-methodological structure of an enabler to participation. a quantitative study, conducted from December of 2010 to March of 2011, with 213 professionals in the FHS in the region of Cariri-Ceará-Brazil. Data were collected through a questionnaire and organized in SPSS 18.0. the level of normative participation becomes manifest beginning with the adolescent search for health services, motivated by disease (77.9%). Normative participation + independence appear when they seek prenatal care and family planning. Emancipatory participation was identified by the frequency of adolescents in group activities, in the schools, and a move in the direction of the level of transformative participation was observed. in this context, it is understood that there exists a need to stimulate the participatory process of the adolescents for a change in health promotion in this group.

Wide-Band Heterodyne Submillimetre Wave Spectrometer for Planetary Atmospheres

NASA Technical Reports Server (NTRS)

Schlecht, Erich

2010-01-01

We present calculations and measurements on a passive submillimetre wave spectroscopic sounder to gather data on the thermal structure, dynamics and composition of the upper atmosphere of a planet, e.g. the stratosphere of Jupiter, or the entire thickness of the atmosphere of Mars. The instrument will be capable of measuring wind speeds, temperature, pressure, and key constituent concentrations in the stratosphere of the target planet. This instrument consists of a Schottky diode based front end and a digital back-end spectrometer. It differs from previous space-based spectrometers in its combination of wide tunability (520-590 GHz), and rapid frequency switching between widely spaced lines within that range. This will enable near simultaneous observation of multiple lines, which is critical to the reconstruction of atmospheric pressure and density versus altitude profiles. At the same time frequency accuracy must be high to enable wind speeds to be determined directly by measurement of the line's Doppler shift.

Fast chirality reversal of the magnetic vortex by electric current

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, W. L., E-mail: wlimnd@gmail.com; Liu, R. H.; Urazhdin, S., E-mail: sergei.urazhdin@emory.edu

2014-12-01

The possibility of high-density information encoding in magnetic materials by topologically stable inhomogeneous magnetization configurations such as domain walls, skyrmions, and vortices has motivated intense research into mechanisms enabling their control and detection. While the uniform magnetization states can be efficiently controlled by electric current using magnetic multilayer structures, this approach has proven much more difficult to implement for inhomogeneous states. Here, we report direct observation of fast reversal of magnetic vortex by electric current in a simple planar structure based on a bilayer of spin Hall material Pt with a single microscopic ferromagnetic disk contacted by asymmetric electrodes. Themore » reversal is enabled by a combination of the chiral Oersted field and spin current generated by the nonuniform current distribution in Pt. Our results provide a route for the efficient control of inhomogeneous magnetization configurations by electric current.« less

Direct CRISPR spacer acquisition from RNA by a natural reverse-transcriptase-Cas1 fusion protein

PubMed Central

Sidote, David J.; Markham, Laura M.; Sanchez-Amat, Antonio; Bhaya, Devaki; Lambowitz, Alan M.; Fire, Andrew Z.

2016-01-01

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat) systems mediate adaptive immunity in diverse prokaryotes. CRISPR-associated Cas1 and Cas2 proteins have been shown to enable adaptation to new threats in Type I and II CRISPR systems by the acquisition of short segments of DNA (“spacers”) from invasive elements. In several Type III CRISPR systems, Cas1 is naturally fused to a reverse transcriptase (RT). In the marine bacterium Marinomonas mediterranea (MMB-1), we show that an RT-Cas1 fusion enables the acquisition of RNA spacers in vivo in an RT-dependent manner. In vitro, the MMB-1 RT-Cas1 and Cas2 proteins catalyze ligation of RNA segments into the CRISPR array, followed by reverse transcription. These observations outline a host-mediated mechanism for reverse information flow from RNA to DNA. PMID:26917774

Enhanced infrared detectors using resonant structures combined with thin type-II superlattice absorbers

DOE PAGES

Goldflam, Michael D.; Kadlec, Emil Andrew; Olson, Ben V.; ...

2016-12-22

Here we examined the spectral responsivity of a 1.77μm thick type-II superlattice based long-wave infrared detector in combination with metallic nanoantennas. Coupling between the Fabry-Pérot cavity formed by the semiconductor layer and the resonant nanoantennas on its surface enables spectral selectivity, while also increasing peak quantum efficiency to over 50%. Electromagnetic simulations reveal that this high responsivity is a direct result of field-enhancement in the absorber layer, enabling significant absorption in spite of the absorber’s subwavelength thickness. Notably, thinning of the absorbing material could ultimately yield lower photodetector noise through a reduction in dark current while improving photocarrier collection efficiency.more » The temperature- and incident-angle-independent spectral response observed in these devices allows for operation over a wide range of temperatures and optical systems. This detector paradigm demonstrates potential benefits to device performance with applications throughout the infrared.« less

Sub-Band Gap Turn-On Near-Infrared-to-Visible Up-Conversion Device Enabled by an Organic-Inorganic Hybrid Perovskite Photovoltaic Absorber.

PubMed

Yu, By Hyeonggeun; Cheng, Yuanhang; Li, Menglin; Tsang, Sai-Wing; So, Franky

2018-05-09

Direct integration of an infrared (IR) photodetector with an organic light-emitting diode (OLED) enables low-cost, pixel-free IR imaging. However, the operation voltage of the resulting IR-to-visible up-conversion is large because of the series device architecture. Here, we report a low-voltage near-IR (NIR)-to-visible up-conversion device using formamidinium lead iodide as a NIR absorber integrated with a phosphorescent OLED. Because of the efficient photocarrier injection from the hybrid perovskite layer to the OLED, we observed a sub-band gap turn-on of the OLED under NIR illumination. The device showed a NIR-to-visible up-conversion efficiency of 3% and a luminance on/off ratio of 10 3 at only 5 V. Finally, we demonstrate pixel-free NIR imaging using the up-conversion device.

Infrared Spectral Radiance Intercomparisons With Satellite and Aircraft Sensors

NASA Technical Reports Server (NTRS)

Larar, Allen M.; Zhou, Daniel K.; Liu, Xu; Smith, William L.

2014-01-01

Measurement system validation is critical for advanced satellite sounders to reach their full potential of improving observations of the Earth's atmosphere, clouds, and surface for enabling enhancements in weather prediction, climate monitoring capability, and environmental change detection. Experimental field campaigns, focusing on satellite under-flights with well-calibrated FTS sensors aboard high-altitude aircraft, are an essential part of the validation task. Airborne FTS systems can enable an independent, SI-traceable measurement system validation by directly measuring the same level-1 parameters spatially and temporally coincident with the satellite sensor of interest. Continuation of aircraft under-flights for multiple satellites during multiple field campaigns enables long-term monitoring of system performance and inter-satellite cross-validation. The NASA / NPOESS Airborne Sounder Testbed - Interferometer (NAST-I) has been a significant contributor in this area by providing coincident high spectral/spatial resolution observations of infrared spectral radiances along with independently-retrieved geophysical products for comparison with like products from satellite sensors being validated. This presentation gives an overview of benefits achieved using airborne sensors such as NAST-I utilizing examples from recent field campaigns. The methodology implemented is not only beneficial to new sensors such as the Cross-track Infrared Sounder (CrIS) flying aboard the Suomi NPP and future JPSS satellites but also of significant benefit to sensors of longer flight heritage such as the Atmospheric InfraRed Sounder (AIRS) and the Infrared Atmospheric Sounding Interferometer (IASI) on the AQUA and METOP-A platforms, respectively, to ensure data quality continuity important for climate and other applications. Infrared spectral radiance inter-comparisons are discussed with a particular focus on usage of NAST-I data for enabling inter-platform cross-validation.

Association of environmental indicators with teen alcohol use and problem behavior: Teens' observations vs. objectively-measured indicators.

PubMed

Byrnes, Hilary F; Miller, Brenda A; Morrison, Christopher N; Wiebe, Douglas J; Woychik, Marcie; Wiehe, Sarah E

2017-01-01

Most prior studies use objectively measured data (e.g., census-based indicators) to assess contextual risks. However, teens' observations might be more important for their risk behavior. 1) determine relationships between observed and objective indicators of contextual risks 2) determine relations of observed and objective indicators with teen alcohol use and problem behavior. Teens aged 14-16 (N=170) carried GPS-enabled smartphones for one month, with locations documented. Ecological momentary assessment (EMA) measured teens' observations via texts regarding risk behaviors and environmental observations. Objective indicators of alcohol outlets and disorganization were spatially joined to EMAs based on teens' location at the time of the texts. Observed and objective disorganization, and objective indicators of alcohol outlets were related to alcohol use. Observed disorganization was related to problem behavior, while objective indicators were unrelated. Findings suggest the importance of considering teens' observations of contextual risk for understanding influences on risk behavior and suggest future directions for research and prevention strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Observations of the marine environment from spaceborne side-looking real aperture radars

NASA Technical Reports Server (NTRS)

Kalmykov, A. I.; Velichko, S. A.; Tsymbal, V. N.; Kuleshov, Yu. A.; Weinman, J. A.; Jurkevich, I.

1993-01-01

Real aperture, side looking X-band radars have been operated from the Soviet Cosmos-1500, -1602, -1766 and Ocean satellites since 1984. Wind velocities were inferred from sea surface radar scattering for speeds ranging from approximately 2 m/s to those of hurricane proportions. The wind speeds were within 10-20 percent of the measured in situ values, and the direction of the wind velocity agreed with in situ direction measurements within 20-50 deg. Various atmospheric mesoscale eddies and tropical cyclones were thus located, and their strengths were inferred from sea surface reflectivity measurements. Rain cells were observed over both land and sea with these spaceborne radars. Algorithms to retrieve rainfall rates from spaceborne radar measurements were also developed. Spaceborne radars have been used to monitor various marine hazards. For example, information derived from those radars was used to plan rescue operations of distressed ships trapped in sea ice. Icebergs have also been monitored, and oil spills were mapped. Tsunamis produced by underwater earthquakes were also observed from space by the radars on the Cosmos 1500 series of satellites. The Cosmos-1500 satellite series have provided all weather radar imagery of the earths surface to a user community in real time by means of a 137.4 MHz Automatic Picture Transmission channel. This feature enabled the radar information to be used in direct support of Soviet polar maritime activities.

A MS-lesion pattern discrimination plot based on geostatistics.

PubMed

Marschallinger, Robert; Schmidt, Paul; Hofmann, Peter; Zimmer, Claus; Atkinson, Peter M; Sellner, Johann; Trinka, Eugen; Mühlau, Mark

2016-03-01

A geostatistical approach to characterize MS-lesion patterns based on their geometrical properties is presented. A dataset of 259 binary MS-lesion masks in MNI space was subjected to directional variography. A model function was fit to express the observed spatial variability in x, y, z directions by the geostatistical parameters Range and Sill. Parameters Range and Sill correlate with MS-lesion pattern surface complexity and total lesion volume. A scatter plot of ln(Range) versus ln(Sill), classified by pattern anisotropy, enables a consistent and clearly arranged presentation of MS-lesion patterns based on geometry: the so-called MS-Lesion Pattern Discrimination Plot. The geostatistical approach and the graphical representation of results are considered efficient exploratory data analysis tools for cross-sectional, follow-up, and medication impact analysis.

Integrated microelectromechanical gyroscope under shock loads

NASA Astrophysics Data System (ADS)

Nesterenko, T. G.; Koleda, A. N.; Barbin, E. S.

2018-01-01

The paper presents a new design of a shock-proof two-axis microelectromechanical gyroscope. Without stoppers, the shock load enables the interaction between the silicon sensor elements. Stoppers were installed in the gyroscope to prevent the contact interaction between electrodes and spring elements with fixed part of the sensor. The contact of stoppers occurs along the plane, thereby preventing the system from serious contact stresses. The shock resistance of the gyroscope is improved by the increase in its eigenfrequency at which the contact interaction does not occur. It is shown that the shock load directed along one axis does not virtually cause the movement of sensing elements along the crosswise axes. Maximum stresses observed in the proposed gyroscope at any loading direction do not exceed the value allowable for silicon.

Adaptive genetic complementarity in mate choice coexists with selection for elaborate sexual traits

PubMed Central

Oh, Kevin P; Badyaev, Alexander V

2006-01-01

Choice of genetically unrelated mates is widely documented, yet it is not known how self-referential mate choice can co-occur with commonly observed directional selection on sexual displays. Across 10 breeding seasons in a wild bird population, we found strong fitness benefits of matings between genetically unrelated partners and show that self-referential choice of genetically unrelated mates alternates with sexual selection on elaborate plumage. Seasonal cycles of diminishing variation in ornamentation, caused by early pairing of the most elaborated males, and influx of increasingly genetically unrelated available mates caused by female-biased dispersal, lead to temporal fluctuations in the target of mate choice and enabled coexistence of directional selection for ornament elaboration with adaptive pairing of genetically unrelated partners. PMID:16822752

Medical Logistics Lessons Observed During Operations Enduring Freedom and Iraqi Freedom.

PubMed

Dole, Mark J; Kissane, Jonathan M

2016-01-01

Medical Logistics (MEDLOG) is a function of the Army's integrated System for Health that provides the medical products and specialized logistics services required to deliver health protection and care under all operational conditions. In unified land operations, MEDLOG is an inherent function of Health Service Support (HSS), which also includes casualty care and medical evacuation. This paper focuses on a few key lessons observed during Operations Enduring Freedom and Iraqi Freedom with direct implications for the support of HSS in future operations as envisioned in the Army Operating Concept and the Joint Concept for Health Services. It also examines a few key enablers that helped mitigate these challenges that are not yet fully acknowledged in Army Medical Department doctrine, policy, and planning.

Nanoaquarium: integrated microchips fabricated by ultrafast laser for understanding phenomena and functions of microorganisms

NASA Astrophysics Data System (ADS)

Sugioka, Koji; Hanada, Yasutaka; Midorikawa, Katsumi; Kawano, Hiroyuki; Ishikawa, Ikuko S.; Miyawaki, Atsushi

2011-12-01

We demonstrate to fabricate microfluidic chips integrated with some functional microcomponents such as optical attenuators and optical waveguides by femtosecond laser direct writing for understanding phenomena and functions of microorganisms. Femtosecond laser irradiation followed by annealing and wet etching in dilute hydrofluoric acid solution resulted in fabrication of three-dimensional microfludic structures embedded in a photosensitive glass. The embedded microfludic structures enabled us to easily and efficiently observe Phormidium gliding to the seedling root, which accelerates growth of the vegetable. In addition, integration of optical attenuators and optical waveguides into the microfluidic structures clarified the mechanism of the gliding movement of Phormidium. We termed such integrated microchips nanoaquariums, realizing the highly efficient and functional observation and analysis of various microorganisms.

The Adaptation of the Moth Pheromone Receptor Neuron to its Natural Stimulus

NASA Astrophysics Data System (ADS)

Kostal, Lubomir; Lansky, Petr; Rospars, Jean-Pierre

2008-07-01

We analyze the first phase of information transduction in the model of the olfactory receptor neuron of the male moth Antheraea polyphemus. We predict such stimulus characteristics that enable the system to perform optimally, i.e., to transfer as much information as possible. Few a priori constraints on the nature of stimulus and stimulus-to-signal transduction are assumed. The results are given in terms of stimulus distributions and intermittency factors which makes direct comparison with experimental data possible. Optimal stimulus is approximatelly described by exponential or log-normal probability density function which is in agreement with experiment and the predicted intermittency factors fall within the lowest range of observed values. The results are discussed with respect to electroantennogram measurements and behavioral observations.

No slip gravity

NASA Astrophysics Data System (ADS)

Linder, Eric V.

2018-03-01

A subclass of the Horndeski modified gravity theory we call No Slip Gravity has particularly interesting properties: 1) a speed of gravitational wave propagation equal to the speed of light, 2) equality between the effective gravitational coupling strengths to matter and light, Gmatter and Glight, hence no slip between the metric potentials, yet difference from Newton's constant, and 3) suppressed growth to give better agreement with galaxy clustering observations. We explore the characteristics and implications of this theory, and project observational constraints. We also give a simple expression for the ratio of the gravitational wave standard siren distance to the photon standard candle distance, in this theory and others, and enable a direct comparison of modified gravity in structure growth and in gravitational waves, an important crosscheck.

Presidential Space Policy Directs NASA to Return Humans to Moon

NASA Image and Video Library

2017-12-11

President Donald Trump signed a new Space Policy Directive-1 at the White House on Monday, Dec. 11, directing NASA’s human spaceflight program back to the Moon, as recommended by the National Space Council.    The directive calls for NASA to lead an innovative and sustainable program of exploration with commercial and international partners to enable human expansion across the solar system, and to bring back to Earth new knowledge and opportunities for human advancement. This effort will more effectively organize government, private industry, and international efforts toward returning humans on the Moon, and will lay the foundation that will eventually enable human exploration of Mars.

APT: what it has enabled us to do

NASA Astrophysics Data System (ADS)

Blacker, Brett S.; Golombek, Daniel

2004-09-01

With the development and operations deployment of the Astronomer's Proposal Tool (APT), Hubble Space Telescope (HST) proposers have been provided with an integrated toolset for Phase I and Phase II. This toolset consists of editors for filling out proposal information, an Orbit Planner for determining observation feasibility, a Visit Planner for determining schedulability, diagnostic and reporting tools and an integrated Visual Target Tuner (VTT) for viewing exposure specifications. The VTT can also overlay HST"s field of view on user-selected Flexible Image Transport System (FITS) images, perform bright object checks and query the HST archive. In addition to these direct benefits for the HST user, STScI"s internal Phase I process has been able to take advantage of the APT products. APT has enabled a substantial streamlining of the process and software processing tools, which enabled a compression by three months of the Phase I to Phase II schedule, allowing to schedule observations earlier and thus further benefiting HST observers. Some of the improvements to our process include: creating a compact disk (CD) of Phase I products; being able to print all proposals on the day of the deadline; link the proposal in Portable Document Format (PDF) with a database, and being able to run all Phase I software on a single platform. In this paper we will discuss the operational results of using APT for HST's Cycles 12 and 13 Phase I process and will show the improvements for the users and the overall process that is allowing STScI to obtain scientific results with HST three months earlier than in previous years. We will also show how APT can be and is being used for multiple missions.

Development of a Compact Captive Balloon and Its Level Supporting

NASA Astrophysics Data System (ADS)

Nakao, Tatsuya; Fujiwara, Kazuhito; Furukawa, Motoyasu; Hiroe, Tetsuyuki

Many kinds of observation techniques have been developed to obtain the properties of atmospheric conditions. The advanced observation techniques of the flow in relatively large scale are remote sensing by satellite facilities, long range observations by radar or Doppler Sodar, etc., while data from conventional climometers set at fixed places are merely limited information about local scale flow. Captive balloons are also available and feasible for the observation of local flows if their standing mechanics are robust against the strong wind and the motion of balloon are stable for all wind direction and the change of wind direction. In this paper, a compact captive balloon (about 2m diam.) for flow measurement is proposed and the preservation of balloon height level and the stabilization of its motion are challenged by using a kite. The relation between force balances acted on the balloon and the balloon height or position was estimated and confirmed in experiments. Although the lift force of single kite worked successfully, it is found that the performance of plural kites is less in the traction of balloon since the interaction of their tensions. The compact balloon supported by the kite enabled the over 300m floating by virtue of the small size causing only low air resistance.

Simulating a Direction-Finder Search for an ELT

NASA Technical Reports Server (NTRS)

Bream, Bruce

2005-01-01

A computer program simulates the operation of direction-finding equipment engaged in a search for an emergency locator transmitter (ELT) aboard an aircraft that has crashed. The simulated equipment is patterned after the equipment used by the Civil Air Patrol to search for missing aircraft. The program is designed to be used for training in radio direction-finding and/or searching for missing aircraft without incurring the expense and risk of using real aircraft and ground search resources. The program places a hidden ELT on a map and enables the user to search for the location of the ELT by moving a 14 NASA Tech Briefs, March 2005 small aircraft image around the map while observing signal-strength and direction readings on a simulated direction- finding locator instrument. As the simulated aircraft is turned and moved on the map, the program updates the readings on the direction-finding instrument to reflect the current position and heading of the aircraft relative to the location of the ELT. The software is distributed in a zip file that contains an installation program. The software runs on the Microsoft Windows 9x, NT, and XP operating systems.

Forecasted masses for 7000 Kepler Objects of Interest

NASA Astrophysics Data System (ADS)

Chen, Jingjing; Kipping, David M.

2018-01-01

Recent transit surveys have discovered thousands of planetary candidates with directly measured radii, but only a small fraction have measured masses. Planetary mass is crucial in assessing the feasibility of numerous observational signatures, such as radial velocities (RVs), atmospheres, moons and rings. In the absence of a direct measurement, a data-driven, probabilistic forecast enables observational planning, and so here we compute posterior distributions for the forecasted mass of ∼7000 Kepler Objects of Interest (KOIs). Our forecasts reveal that the predicted RV amplitudes of Neptunian planets are relatively consistent, as a result of transit survey detection bias, hovering around a few m s-1 level. We find that mass forecasts are unlikely to improve through more precise planetary radii, with the error budget presently dominated by the intrinsic model uncertainty. Our forecasts identify a couple of dozen KOIs near the Terran-Neptunian divide with particularly large RV semi-amplitudes, which could be promising targets to follow up, particularly in the near-infrared. With several more transit surveys planned in the near-future, the need to quickly forecast observational signatures is likely to grow, and the work here provides a template example of such calculations.

Direct observation of isolated Damon-Eshbach and backward volume spin-wave packets in ferromagnetic microstripes

PubMed Central

Wessels, Philipp; Vogel, Andreas; Tödt, Jan-Niklas; Wieland, Marek; Meier, Guido; Drescher, Markus

2016-01-01

The analysis of isolated spin-wave packets is crucial for the understanding of magnetic transport phenomena and is particularly interesting for applications in spintronic and magnonic devices, where isolated spin-wave packets implement an information processing scheme with negligible residual heat loss. We have captured microscale magnetization dynamics of single spin-wave packets in metallic ferromagnets in space and time. Using an optically driven high-current picosecond pulse source in combination with time-resolved scanning Kerr microscopy probed by femtosecond laser pulses, we demonstrate phase-sensitive real-space observation of spin-wave packets in confined permalloy (Ni80Fe20) microstripes. Impulsive excitation permits extraction of the dynamical parameters, i.e. phase- and group velocities, frequencies and wave vectors. In addition to well-established Damon-Eshbach modes our study reveals waves with counterpropagating group- and phase-velocities. Such unusual spin-wave motion is expected for backward volume modes where the phase fronts approach the excitation volume rather than emerging out of it due to the negative slope of the dispersion relation. These modes are difficult to excite and observe directly but feature analogies to negative refractive index materials, thus enabling model studies of wave propagation inside metamaterials. PMID:26906113

Robust interferometric imaging via prior-less phase recovery: redundant spacing calibration with generalized-closure phases

NASA Astrophysics Data System (ADS)

Kurien, Binoy G.; Ashcom, Jonathan B.; Shah, Vinay N.; Rachlin, Yaron; Tarokh, Vahid

2017-01-01

Atmospheric turbulence presents a fundamental challenge to Fourier phase recovery in optical interferometry. Typical reconstruction algorithms employ Bayesian inference techniques which rely on prior knowledge of the scene under observation. In contrast, redundant spacing calibration (RSC) algorithms employ redundancy in the baselines of the interferometric array to directly expose the contribution of turbulence, thereby enabling phase recovery for targets of arbitrary and unknown complexity. Traditionally RSC algorithms have been applied directly to single-exposure measurements, which are reliable only at high photon flux in general. In scenarios of low photon flux, such as those arising in the observation of dim objects in space, one must instead rely on time-averaged, atmosphere-invariant quantities such as the bispectrum. In this paper, we develop a novel RSC-based algorithm for prior-less phase recovery in which we generalize the bispectrum to higher order atmosphere-invariants (n-spectra) for improved sensitivity. We provide a strategy for selection of a high-signal-to-noise ratio set of n-spectra using the graph-theoretic notion of the minimum cycle basis. We also discuss a key property of this set (wrap-invariance), which then enables reliable application of standard linear estimation techniques to recover the Fourier phases from the 2π-wrapped n-spectra phases. For validation, we analyse the expected shot-noise-limited performance of our algorithm for both pairwise and Fizeau interferometric architectures, and corroborate this analysis with simulation results showing performance near an atmosphere-oracle Cramer-Rao bound. Lastly, we apply techniques from the field of compressed sensing to perform image reconstruction from the estimated complex visibilities.

Spatial Object Recognition Enables Endogenous LTD that Curtails LTP in the Mouse Hippocampus

PubMed Central

Goh, Jinzhong Jeremy

2013-01-01

Although synaptic plasticity is believed to comprise the cellular substrate for learning and memory, limited direct evidence exists that hippocampus-dependent learning actually triggers synaptic plasticity. It is likely, however, that long-term potentiation (LTP) works in concert with its counterpart, long-term depression (LTD) in the creation of spatial memory. It has been reported in rats that weak synaptic plasticity is facilitated into persistent plasticity if afferent stimulation is coupled with a novel spatial learning event. It is not known if this phenomenon also occurs in other species. We recorded from the hippocampal CA1 of freely behaving mice and observed that novel spatial learning triggers endogenous LTD. Specifically, we observed that LTD is enabled when test-pulse afferent stimulation is given during the learning of object constellations or during a spatial object recognition task. Intriguingly, LTP is significantly impaired by the same tasks, suggesting that LTD is the main cellular substrate for this type of learning. These data indicate that learning-facilitated plasticity is not exclusive to rats and that spatial learning leads to endogenous LTD in the hippocampus, suggesting an important role for this type of synaptic plasticity in the creation of hippocampus-dependent memory. PMID:22510536

Development Status of Adjustable X-ray Optics with 0.5 Arcsec Imaging for the X-ray Surveyor Mission Concept

NASA Astrophysics Data System (ADS)

Reid, Paul B.; Allured, Ryan; ben-Ami, Sagi; Cotroneo, Vincenzo; Schwartz, Daniel A.; Tananbaum, Harvey; Vikhlinin, Alexey; Trolier-McKinstry, Susan; Wallace, Margeaux L.; Jackson, Tom

2016-04-01

The X-ray Surveyor mission concept is designed as a successor to the Chandra X-ray Observatory. As currently envisioned, it will have as much as 30-50 times the collecting area of Chandra with the same 0.5 arcsec imaging resolution. This combination of telescope area and imaging resolution, along with a detector suite for imaging and dispersive and non-dispersive imaging spectroscopy, will enable a wide range of astrophysical observations. These observations will include studies of the growth of large scale structure, early black holes and the growth of SMBHs, and high resolution spectroscopy with arcsec resolution, among many others. We describe the development of adjustable grazing incidence X-ray optics, a potential technology for the high resolution, thin, lightweight mirrors. We discuss recent advancements including the demonstration of deterministic figure correction via the use of the adjusters, the successful demonstration of integrating control electronics directly on the actuator cells to enable row-column addressing, and discuss the feasibility of on-orbit piezoelectric performance and figure monitoring via integrated semiconductor strain gauges. We also present the telescope point design and progress in determining the telescope thermal sensitivities and achieving alignment and mounting requirements.

Peltier cooling in molecular junctions

NASA Astrophysics Data System (ADS)

Cui, Longji; Miao, Ruijiao; Wang, Kun; Thompson, Dakotah; Zotti, Linda Angela; Cuevas, Juan Carlos; Meyhofer, Edgar; Reddy, Pramod

2018-02-01

The study of thermoelectricity in molecular junctions is of fundamental interest for the development of various technologies including cooling (refrigeration) and heat-to-electricity conversion1-4. Recent experimental progress in probing the thermopower (Seebeck effect) of molecular junctions5-9 has enabled studies of the relationship between thermoelectricity and molecular structure10,11. However, observations of Peltier cooling in molecular junctions—a critical step for establishing molecular-based refrigeration—have remained inaccessible. Here, we report direct experimental observations of Peltier cooling in molecular junctions. By integrating conducting-probe atomic force microscopy12,13 with custom-fabricated picowatt-resolution calorimetric microdevices, we created an experimental platform that enables the unified characterization of electrical, thermoelectric and energy dissipation characteristics of molecular junctions. Using this platform, we studied gold junctions with prototypical molecules (Au-biphenyl-4,4'-dithiol-Au, Au-terphenyl-4,4''-dithiol-Au and Au-4,4'-bipyridine-Au) and revealed the relationship between heating or cooling and charge transmission characteristics. Our experimental conclusions are supported by self-energy-corrected density functional theory calculations. We expect these advances to stimulate studies of both thermal and thermoelectric transport in molecular junctions where the possibility of extraordinarily efficient energy conversion has been theoretically predicted2-4,14.

Cyber Enabled Direct Digital Manufacturing

DTIC Science & Technology

2015-05-15

5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) The Pennsylvania State University Applied Research Labotatory Office of...MONITORING AGENCY NAME(S) AND ADDRESS(ES) Office of Naval Research 875 North Randolph Street Arlington, VA 22203-1995 10. SPONSOR/MONITOR’S ACRONYM(S...the Office of Naval Research "Cyber Enabled Direct Digital Manufacturing" program, award N00014-11-1-0668 are discussed. Achievements include the

NASA's Advanced Information Systems Technology (AIST) Program: Advanced Concepts and Disruptive Technologies

NASA Astrophysics Data System (ADS)

Little, M. M.; Moe, K.; Komar, G.

2014-12-01

NASA's Earth Science Technology Office (ESTO) manages a wide range of information technology projects under the Advanced Information Systems Technology (AIST) Program. The AIST Program aims to support all phases of NASA's Earth Science program with the goal of enabling new observations and information products, increasing the accessibility and use of Earth observations, and reducing the risk and cost of satellite and ground based information systems. Recent initiatives feature computational technologies to improve information extracted from data streams or model outputs and researchers' tools for Big Data analytics. Data-centric technologies enable research communities to facilitate collaboration and increase the speed with which results are produced and published. In the future NASA anticipates more small satellites (e.g., CubeSats), mobile drones and ground-based in-situ sensors will advance the state-of-the-art regarding how scientific observations are performed, given the flexibility, cost and deployment advantages of new operations technologies. This paper reviews the success of the program and the lessons learned. Infusion of these technologies is challenging and the paper discusses the obstacles and strategies to adoption by the earth science research and application efforts. It also describes alternative perspectives for the future program direction and for realizing the value in the steps to transform observations from sensors to data, to information, and to knowledge, namely: sensor measurement concepts development; data acquisition and management; data product generation; and data exploitation for science and applications.

Partner Enabling of Substance Use Disorders: Critical Review and Future Directions.

ERIC Educational Resources Information Center

Rotunda, Rob J.; Doman, Kathy

2001-01-01

Substance use disorders affect not only the identified client but significant others as well. This article contrasts the enabling and codependency constructs, reviews empirical studies of enabling, and offers a conceptualization of partner responses to addiction that could enhance future research efforts and clinical applications in this area. (BF)

Active Learning and Engagement with the Wireless Indoor Location Device (WILD) Learning System

NASA Astrophysics Data System (ADS)

Moldwin, M.; Samson, P. J.; Ojeda, L.; Miller, T.; Yu, J.

2016-12-01

The Wireless Indoor Location Device (WILD) Learning System being developed at the University of Michigan and the Education Technology company A2 Motus LLC provides a unique platform for social learning by allowing students to become active participants in live simulations of complex systems, like hurricane formation. The WILD Learning System enables teachers to engage students in kinesthetic activities that explore complex models from a wide variety of STEAM (Science, Technology, Engineering, Art and Math) disciplines. The system provides students' location, orientation and motion within the classroom and assigns each student different parameters depending on the activity. For example, students learning about hurricanes could be assigned atmospheric pressure levels and asked to arrange themselves around the room to simulate a hurricane. The Wild Learning System software then takes the students' pressure readings and locations and projects their locations overlaid onto a real-time generated simulated pressure weather map enabling the observation of how their arrangement influences the pressure structure. The teacher then could have the students orient themselves in the direction they think the resulting wind field will be based on the pressure contours as the system can show an arrow originating from each of the students position in the direction that they are facing. The system also could incorporate a student response-type system for the instructor to then directly question students about other concepts and record their response to both the kinesthetic activity and other formative assessment questions. The WILD Learning System consists of a sensor package for each student in the class, beacons to enable precise localization of the students, software to calculate student location information, and educational software for a variety of activities. In addition, a software development kit (SDK) is under development that would allow others to create additional learning activities using the WILD Learning System. (WILD Learning System development has been partially supported by NASA's CYGNSS Mission EPO, the NSF and the University of Michigan).

X-ray intravital microscopy for functional imaging in rat hearts using synchrotron radiation coronary microangiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Umetani, K.; Fukushima, K.

2013-03-15

An X-ray intravital microscopy technique was developed to enable in vivo visualization of the coronary, cerebral, and pulmonary arteries in rats without exposure of organs and with spatial resolution in the micrometer range and temporal resolution in the millisecond range. We have refined the system continually in terms of the spatial resolution and exposure time. X-rays transmitted through an object are detected by an X-ray direct-conversion type detector, which incorporates an X-ray SATICON pickup tube. The spatial resolution has been improved to 6 {mu}m, yielding sharp images of small arteries. The exposure time has been shortened to around 2 msmore » using a new rotating-disk X-ray shutter, enabling imaging of beating rat hearts. Quantitative evaluations of the X-ray intravital microscopy technique were extracted from measurements of the smallest-detectable vessel size and detection of the vessel function. The smallest-diameter vessel viewed for measurements is determined primarily by the concentration of iodinated contrast material. The iodine concentration depends on the injection technique. We used ex vivo rat hearts under Langendorff perfusion for accurate evaluation. After the contrast agent is injected into the origin of the aorta in an isolated perfused rat heart, the contrast agent is delivered directly into the coronary arteries with minimum dilution. The vascular internal diameter response of coronary arterial circulation is analyzed to evaluate the vessel function. Small blood vessels of more than about 50 {mu}m diameters were visualized clearly at heart rates of around 300 beats/min. Vasodilation compared to the control was observed quantitatively using drug manipulation. Furthermore, the apparent increase in the number of small vessels with diameters of less than about 50 {mu}m was observed after the vasoactive agents increased the diameters of invisible small blood vessels to visible sizes. This technique is expected to offer the potential for direct investigation of mechanisms of vascular dysfunctions.« less

Investigation of Surface Waves in Deep and Shallow Water using Coherent Radars at Grazing Incidence

NASA Astrophysics Data System (ADS)

Buckley, M.; Horstmann, J.; Carrasco, R.; Seemann, J.; Stresser, M.

2016-02-01

Coherent microwave radars operating at X-band near grazing incidence are utilized to measure the backscatter intensity and Doppler velocity from the small-scale surface roughness of the ocean. The radar backscatter is dependent on the wind and strongly modulated by the surface waves and therefore enables to retrieve the surface wind as well as surface waves. The radar measured Doppler velocities are also modulated by contributions from the wind, current and waves and allow getting additional information on these parameters. In addition coherent marine radars allow to observe breaking waves, which lead to a increase in radar backscatter as well as a strong change of the Doppler speed.Within this presentation we will introduce and validate new methods to measure spectral wave properties such as wave directions, periods and significant wave height from coherent marine radars. The methods have been applied in deep and shallow water and validated to measurements of directional wave riders as well as an Acoustic Wave and Current Profiler. These comparisons show an overall excellent performance of coherent radars for the retrieval of spectral wave properties (e.g. Hs rms of 0.2 m). Furthermore, new methodologies will be presented that enable to observe and quantify wave breaking in deep water as well as in the littoral zone. The above mentioned methods have been applied to investigate the influence of Offshore Wind Farms (OWF) on the wave field with respect to the spectral properties as well as the amount of wave breaking. We will present the results obtained during a cruise in May 2015 within and around the OWF Dantysk in the German Bight of the North Sea, which consist of eighty 3.5 MW wind turbines. In addition we will present our initial results on the investigation of wave dissipation in the littoral zone at the coast of the island Sylt using marine radars, pressure gauges as well as directional wave riders.

Understanding in-situ ozone production in the summertime through radical observations and modelling studies during the Clean air for London project

NASA Astrophysics Data System (ADS)

Whalley, Lisa; Stone, Daniel; Sharp, Thomas; Garraway, Shani; Bannan, Thomas; Percival, Carl; Hopkins, James; Holmes, Rachel; Hamilton, Jacqui; Lee, James; Laufs, Sebastian; Kleffmann, Jörg; Heard, Dwayne

2014-05-01

With greater than 50 % of the global population residing in urban conurbations, poor urban air quality has a demonstrable effect on human health. OH and HO2 radicals, (collectively termed HOx) together with RO2 radicals, mediate virtually all of the oxidative chemistry in the atmosphere, being responsible for the transformation of primary emissions into secondary pollutants such as NO2, O3 and particulates. Here we present measurements of OH, HO2, partially speciated RO2 (distinguishing smaller alkane related RO2 from larger alkane/alkene/aromatic related RO2), ClNO2 and OH reactivity measurements taken during the ClearfLo campaign in central London in the summer of 2012. Comparison with calculations from a detailed box model utilising the Master Chemical Mechanism v3.2 tested our ability to reproduce radical levels, and enabled detailed radical budgets to be determined, highlighting for example the important role of the photolysis of nitrous acid (HONO) and carbonyl species as radical sources. Speciation of RO2 enabled the break-down of ozone production from different classes of VOCs to be calculated directly and compared with model calculations. Summertime observations of radicals have helped to identify that increases in photolytic sources of radicals on warm, sunny days can significantly increase local ozone concentrations leading to exceedances of EU air quality recommendations of 60 ppbV. The photolytic breakdown of ClNO2 to Cl atoms can more than double radical concentrations in the early morning; although the integrated increase in radical concentrations over a 24 hr period in model runs when ClNO2 photolysis is included is more modest. On average we calculate just under a 1 ppb increase in ozone due to the presence of ClNO2 in London air. OH reactivity was found to be greatest during morning and evening rush hours. Good agreement between the modelled OH reactivity and observations could be achieved when reactivity associated with model generated photo-oxidation products was considered in addition to the measured primary OH reactants. Carbonyl species such as formaldehyde, acetaldehyde and acetone have been identified as the VOC class dominating organic OH reactivity. As such, together with the direct radical source contribution by photolysis, these species dominate local ozone production in London. Modelling studies comparing the observed carbonyl concentrations with model predictions suggest that over 50% of the total concentration may be directly emitted and, hence, London's in-situ chemistry may be considered to contribute significantly to the ozone levels observed.

Bidentate, monoanionic auxiliary-directed functionalization of carbon-hydrogen bonds.

PubMed

Daugulis, Olafs; Roane, James; Tran, Ly Dieu

2015-04-21

In recent years, carbon-hydrogen bond functionalization has evolved from an organometallic curiosity to a tool used in mainstream applications in the synthesis of complex natural products and drugs. The use of C-H bonds as a transformable functional group is advantageous because these bonds are the most abundant functionality in organic molecules. One-step conversion of these bonds to the desired functionality shortens synthetic pathways, saving reagents, solvents, and labor. Less chemical waste is generated as well, showing that this chemistry is environmentally beneficial. This Account describes the development and use of bidentate, monoanionic auxiliaries for transition-metal-catalyzed C-H bond functionalization reactions. The chemistry was initially developed to overcome the limitations with palladium-catalyzed C-H bond functionalization assisted by monodentate directing groups. By the use of electron-rich bidentate directing groups, functionalization of unactivated sp(3) C-H bonds under palladium catalysis has been developed. Furthermore, a number of abundant base-metal complexes catalyze functionalization of sp(2) C-H bonds. At this point, aminoquinoline, picolinic acid, and related compounds are among the most used and versatile directing moieties in C-H bond functionalization chemistry. These groups facilitate catalytic functionalization of sp(2) and sp(3) C-H bonds by iron, cobalt, nickel, copper, ruthenium, rhodium, and palladium complexes. Exceptionally general reactivity is observed, enabling, among other transformations, direct arylation, alkylation, fluorination, sulfenylation, amination, etherification, carbonylation, and alkenylation of carbon-hydrogen bonds. The versatility of these auxilaries can be attributed to the following factors. First, they are capable of stabilizing high oxidation states of transition metals, thereby facilitating the C-H bond functionalization step. Second, the directing groups can be removed, enabling their use in synthesis and functionalization of natural products and medicinally relevant substances. While the development of these directing groups presents a significant advance, several limitations of this methodology are apparent. The use of expensive second-row transition metal catalysts is still required for efficient sp(3) C-H bond functionalization. Furthermore, the need to install and subsequently remove the relatively expensive directing group is a disadvantage.

Bidentate, Monoanionic Auxiliary-Directed Functionalization of Carbon–Hydrogen Bonds

PubMed Central

Daugulis, Olafs; Roane, James; Tran, Ly Dieu

2015-01-01

CONSPECTUS In recent years, carbon–hydrogen bond functionalization has evolved from an organometallic curiosity to mainstream applications in the synthesis of complex natural products and drugs. The use of C–H bonds as a transformable functional group is advantageous because these bonds are the most abundant functionality in organic molecules. One-step conversion of these bonds to the desired functionality shortens synthetic pathways, saving reagents, solvents, and labor. Less chemical waste is generated as well, showing that this chemistry is environmentally beneficial. This Account describes the development and use of bidentate, monoanionic auxiliaries for transition-metal-catalyzed C–H bond functionalization reactions. The chemistry was initially developed to overcome the limitations with palladium-catalyzed C–H bond functionalization assisted by monodentate directing groups. By the use of electron-rich bidentate directing groups, functionalization of unactivated sp3 C–H bonds under palladium catalysis has been developed. Furthermore, a number of abundant base-metal complexes catalyze functionalization of sp2 C–H bonds. At this point, aminoquinoline, picolinic acid, and related compounds are among the most used and versatile directing moieties in C–H bond functionalization chemistry. These groups facilitate catalytic functionalization of sp2 and sp3 C–H bonds by iron, cobalt, nickel, copper, ruthenium, rhodium, and palladium complexes. Exceptionally general reactivity is observed, enabling, among other transformations, direct arylation, alkylation, fluorination, sulfenylation, amination, etherification, carbonylation, and alkenylation of carbon–hydrogen bonds. The versatility of these auxilaries can be attributed to the following factors. First, they are capable of stabilizing high oxidation states of transition metals, thereby facilitating the C–H bond functionalization step. Second, the directing groups can be removed, enabling their use in synthesis and functionalization of natural products and medicinally relevant substances. While the development of these directing groups presents a significant advance, several limitations of this methodology are apparent. The use of expensive second-row transition metal catalysts is still required for efficient sp3 C–H bond functionalization. Furthermore, a disadvantage is the need to install and subsequently remove the relatively expensive directing group. PMID:25756616

Deciphering protein signatures using color, morphological, and topological analysis of immunohistochemically stained human tissues

NASA Astrophysics Data System (ADS)

Zerhouni, Erwan; Prisacari, Bogdan; Zhong, Qing; Wild, Peter; Gabrani, Maria

2016-03-01

Images of tissue specimens enable evidence-based study of disease susceptibility and stratification. Moreover, staining technologies empower the evidencing of molecular expression patterns by multicolor visualization, thus enabling personalized disease treatment and prevention. However, translating molecular expression imaging into direct health benefits has been slow. Two major factors contribute to that. On the one hand, disease susceptibility and progression is a complex, multifactorial molecular process. Diseases, such as cancer, exhibit cellular heterogeneity, impeding the differentiation between diverse grades or types of cell formations. On the other hand, the relative quantification of the stained tissue selected features is ambiguous, tedious and time consuming, prone to clerical error, leading to intra- and inter-observer variability and low throughput. Image analysis of digital histopathology images is a fast-developing and exciting area of disease research that aims to address the above limitations. We have developed a computational framework that extracts unique signatures using color, morphological and topological information and allows the combination thereof. The integration of the above information enables diagnosis of disease with AUC as high as 0.97. Multiple staining show significant improvement with respect to most proteins, and an AUC as high as 0.99.

Single-neuron identification of chemical constituents, physiological changes, and metabolism using mass spectrometry.

PubMed

Zhu, Hongying; Zou, Guichang; Wang, Ning; Zhuang, Meihui; Xiong, Wei; Huang, Guangming

2017-03-07

The use of single-cell assays has emerged as a cutting-edge technique during the past decade. Although single-cell mass spectrometry (MS) has recently achieved remarkable results, deep biological insights have not yet been obtained, probably because of various technical issues, including the unavoidable use of matrices, the inability to maintain cell viability, low throughput because of sample pretreatment, and the lack of recordings of cell physiological activities from the same cell. In this study, we describe a patch clamp/MS-based platform that enables the sensitive, rapid, and in situ chemical profiling of single living neurons. This approach integrates modified patch clamp technique and modified MS measurements to directly collect and detect nanoliter-scale samples from the cytoplasm of single neurons in mice brain slices. Abundant possible cytoplasmic constituents were detected in a single neuron at a relatively fast rate, and over 50 metabolites were identified in this study. The advantages of direct, rapid, and in situ sampling and analysis enabled us to measure the biological activities of the cytoplasmic constituents in a single neuron, including comparing neuron types by cytoplasmic chemical constituents; observing changes in constituent concentrations as the physiological conditions, such as age, vary; and identifying the metabolic pathways of small molecules.

Single-neuron identification of chemical constituents, physiological changes, and metabolism using mass spectrometry

PubMed Central

Zhu, Hongying; Zou, Guichang; Wang, Ning; Zhuang, Meihui; Xiong, Wei; Huang, Guangming

2017-01-01

The use of single-cell assays has emerged as a cutting-edge technique during the past decade. Although single-cell mass spectrometry (MS) has recently achieved remarkable results, deep biological insights have not yet been obtained, probably because of various technical issues, including the unavoidable use of matrices, the inability to maintain cell viability, low throughput because of sample pretreatment, and the lack of recordings of cell physiological activities from the same cell. In this study, we describe a patch clamp/MS-based platform that enables the sensitive, rapid, and in situ chemical profiling of single living neurons. This approach integrates modified patch clamp technique and modified MS measurements to directly collect and detect nanoliter-scale samples from the cytoplasm of single neurons in mice brain slices. Abundant possible cytoplasmic constituents were detected in a single neuron at a relatively fast rate, and over 50 metabolites were identified in this study. The advantages of direct, rapid, and in situ sampling and analysis enabled us to measure the biological activities of the cytoplasmic constituents in a single neuron, including comparing neuron types by cytoplasmic chemical constituents; observing changes in constituent concentrations as the physiological conditions, such as age, vary; and identifying the metabolic pathways of small molecules. PMID:28223513

Deep-Sea DuraFET: A Pressure Tolerant pH Sensor Designed for Global Sensor Networks.

PubMed

Johnson, Kenneth S; Jannasch, Hans W; Coletti, Luke J; Elrod, Virginia A; Martz, Todd R; Takeshita, Yuichiro; Carlson, Robert J; Connery, James G

2016-03-15

Increasing atmospheric carbon dioxide is driving a long-term decrease in ocean pH which is superimposed on daily to seasonal variability. These changes impact ecosystem processes, and they serve as a record of ecosystem metabolism. However, the temporal variability in pH is observed at only a few locations in the ocean because a ship is required to support pH observations of sufficient precision and accuracy. This paper describes a pressure tolerant Ion Sensitive Field Effect Transistor pH sensor that is based on the Honeywell Durafet ISFET die. When combined with a AgCl pseudoreference sensor that is immersed directly in seawater, the system is capable of operating for years at a time on platforms that cycle from depths of several km to the surface. The paper also describes the calibration scheme developed to allow calibrated pH measurements to be derived from the activity of HCl reported by the sensor system over the range of ocean pressure and temperature. Deployments on vertical profiling platforms enable self-calibration in deep waters where pH values are stable. Measurements with the sensor indicate that it is capable of reporting pH with an accuracy of 0.01 or better on the total proton scale and a precision over multiyear periods of 0.005. This system enables a global ocean observing system for ocean pH.

Advanced platform technologies for Earth science

NASA Astrophysics Data System (ADS)

Lemmerman, Loren; Raymond, Carol; Shotwell, Robert; Chase, James; Bhasin, Kul; Connerton, Robert

2005-01-01

Historically, Earth science investigations have been independent and highly focused. However, the Earth's environment is a very dynamic and interrelated system and to understand it, significant improvements in spatial and temporal observations will be required. Science needs to document the need for constellations to achieve desired spatial and temporal observations. A key element envisioned for accomplishing these difficult challenges is the idea of a distributed, heterogeneous, and adaptive observing system or sensor web. This paper focuses on one possible approach based on a LEO constellation composed of 100 spacecraft. A cost analysis has been done to indicate the financial pressures of each mission phase and conclusions are drawn suggesting that new technology investments are needed, directed toward lowering production costs; that operations costs will need to be reduced through autonomy; and that, of the on-board subsystems considered, advanced power generation and management may be the most enabling of new technologies.

Direct observation of bis(dicarbollyl)nickel conformers in solution by fluorescence spectroscopy: an approach to redox-controlled metallacarborane molecular motors.

PubMed

Safronov, Alexander V; Shlyakhtina, Natalia I; Everett, Thomas A; VanGordon, Monika R; Sevryugina, Yulia V; Jalisatgi, Satish S; Hawthorne, M Frederick

2014-10-06

As a continuation of work on metallacarborane-based molecular motors, the structures of substituted bis(dicarbollyl)nickel complexes in Ni(III) and Ni(IV) oxidation states were investigated in solution by fluorescence spectroscopy. Symmetrically positioned cage-linked pyrene molecules served as fluorescent probes to enable the observation of mixed meso-trans/dl-gauche (pyrene monomer fluorescence) and dl-cis/dl-gauche (intramolecular pyrene excimer fluorescence with residual monomer fluorescence) cage conformations of the nickelacarboranes in the Ni(III) and Ni(IV) oxidation states, respectively. The absence of energetically disfavored conformers in solution--dl-cis in the case of nickel(III) complexes and meso-trans in the case of nickel(IV)--was demonstrated based on spectroscopic data and conformer energy calculations in solution. The conformational persistence observed in solution indicates that bis(dicarbollyl)nickel complexes may provide attractive templates for building electrically driven and/or photodriven molecular motors.

NGC 2024: Far-infrared and radio molecular observations

NASA Technical Reports Server (NTRS)

Thronson, H. A., Jr.; Lada, C. J.; Schwartz, P. R.; Smith, H. A.; Smith, J.; Glaccum, W.; Harper, D. A.; Loewenstein, R. F.

1984-01-01

Far infrared continuum and millimeter wave molecular observations are presented for the infrared and radio source NGC 2024. The measurements are obtained at relatively high angular resolution, enabling a description of the source energetics and mass distribution in greater detail than previously reported. The object appears to be dominated by a dense ridge of material, extended in the north/south direction and centered on the dark lane that is seen in visual photographs. Maps of the source using the high density molecules CS and HCN confirm this picture and allow a description of the core structure and molecular abundances. The radio molecular and infrared observations support the idea that an important exciting star in NGC 2024 has yet to be identified and is centered on the dense ridge about 1' south of the bright mid infrared source IRS 2. The data presented here allows a presentation of a model for the source.

The W. M. Keck Observatory Infrared Vortex Coronagraph and a First Image of HIP 79124 B

NASA Astrophysics Data System (ADS)

Serabyn, E.; Huby, E.; Matthews, K.; Mawet, D.; Absil, O.; Femenia, B.; Wizinowich, P.; Karlsson, M.; Bottom, M.; Campbell, R.; Carlomagno, B.; Defrère, D.; Delacroix, C.; Forsberg, P.; Gomez Gonzalez, C.; Habraken, S.; Jolivet, A.; Liewer, K.; Lilley, S.; Piron, P.; Reggiani, M.; Surdej, J.; Tran, H.; Vargas Catalán, E.; Wertz, O.

2017-01-01

An optical vortex coronagraph has been implemented within the NIRC2 camera on the Keck II telescope and used to carry out on-sky tests and observations. The development of this new L‧-band observational mode is described, and an initial demonstration of the new capability is presented: a resolved image of the low-mass companion to HIP 79124, which had previously been detected by means of interferometry. With HIP 79124 B at a projected separation of 186.5 mas, both the small inner working angle of the vortex coronagraph and the related imaging improvements were crucial in imaging this close companion directly. Due to higher Strehl ratios and more relaxed contrasts in L‧ band versus H band, this new coronagraphic capability will enable high-contrast, small-angle observations of nearby young exoplanets and disks on a par with those of shorter-wavelength extreme adaptive optics coronagraphs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serabyn, E.; Liewer, K.; Huby, E.

An optical vortex coronagraph has been implemented within the NIRC2 camera on the Keck II telescope and used to carry out on-sky tests and observations. The development of this new L ′-band observational mode is described, and an initial demonstration of the new capability is presented: a resolved image of the low-mass companion to HIP 79124, which had previously been detected by means of interferometry. With HIP 79124 B at a projected separation of 186.5 mas, both the small inner working angle of the vortex coronagraph and the related imaging improvements were crucial in imaging this close companion directly. Duemore » to higher Strehl ratios and more relaxed contrasts in L ′ band versus H band, this new coronagraphic capability will enable high-contrast, small-angle observations of nearby young exoplanets and disks on a par with those of shorter-wavelength extreme adaptive optics coronagraphs.« less

AFSC Standardization Conference, 1553, 1589, 1750, 1760, Ada, November 18-20, 1980, Dayton Convention Center, Dayton, Ohio, Volume II. Proceedings Standards,

DTIC Science & Technology

1980-11-01

4006 DMAE Direct Memory Access Enable: ’Ibis command enables direct memory access (DMA). 4007 I)MAi) Direct Memory Access Disable: This command...72 DLI 72 DLR 72 DM 111 DMAD 30 DMAE 30 DMR 111 ONEG 103 DR 117 DS 104 OSAR 53 141 373 ’., M1L-STD-1750A (USAF) 2 July 1980 OSBI 29 OSCR 54 OSIC 48...in 4.7.7, the connectors shall show no defects detrimental to the operation of the connectors and shall A-7 461 -meet the subsequent test requirements

Einstein's Elevator in Class: A Self-Construction by Students for the Study of the Equivalence Principle

NASA Astrophysics Data System (ADS)

Kapotis, Efstratios; Kalkanis, George

2016-10-01

According to the principle of equivalence, it is impossible to distinguish between gravity and inertial forces that a noninertial observer experiences in his own frame of reference. For example, let's consider an elevator in space that is being accelerated in one direction. An observer inside it would feel as if there was gravity force pulling him toward the opposite direction. The same holds for a person in a stationary elevator located in Earth's gravitational field. No experiment enables us to distinguish between the accelerating elevator in space and the motionless elevator near Earth's surface. Strictly speaking, when the gravitational field is non-uniform (like Earth's), the equivalence principle holds only for experiments in elevators that are small enough and that take place over a short enough period of time (Fig. 1). However, performing an experiment in an elevator in space is impractical. On the other hand, it is easy to combine both forces on the same observer, i.e., gravity and a fictitious inertial force due to acceleration. Imagine an observer in an elevator that falls freely within Earth's gravitational field. The observer experiences gravity pulling him down while it might be said that the inertial force due to gravity acceleration g pulls him up. Gravity and inertial force cancel each other, (mis)leading the observer to believe there is no gravitational field. This study outlines our implementation of a self-construction idea that we have found useful in teaching introductory physics students (undergraduate, non-majors).

Microfluidic Device to Quantify the Behavior of Therapeutic Bacteria in Three-Dimensional Tumor Tissue.

PubMed

Brackett, Emily L; Swofford, Charles A; Forbes, Neil S

2016-01-01

Microfluidic devices enable precise quantification of the interactions between anti-cancer bacteria and tumor tissue. Direct observation of bacterial movement and gene expression in tissue is difficult with either monolayers of cells or tumor-bearing mice. Quantification of these interactions is necessary to understand the inherent mechanisms of bacterial targeting and to develop modified organisms with enhanced therapeutic properties. Here we describe the procedures for designing, printing, and assembling microfluidic tumor-on-a-chip devices. We also describe the procedures for inserting three-dimensional tumor-cell masses, exposure to bacteria, and analyzing the resultant images.

Experimental demonstration of quantum teleportation of broadband squeezing.

PubMed

Yonezawa, Hidehiro; Braunstein, Samuel L; Furusawa, Akira

2007-09-14

We demonstrate an unconditional high-fidelity teleporter capable of preserving the broadband entanglement in an optical squeezed state. In particular, we teleport a squeezed state of light and observe -0.8+/-0.2 dB of squeezing in the teleported (output) state. We show that the squeezing criterion translates directly into a sufficient criterion for entanglement of the upper and lower sidebands of the optical field. Thus, this result demonstrates the first unconditional teleportation of broadband entanglement. Our teleporter achieves sufficiently high fidelity to allow the teleportation to be cascaded, enabling, in principle, the construction of deterministic non-Gaussian operations.

Flexible nanomembrane photonic-crystal cavities for tensilely strained-germanium light emission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yin, Jian; Wang, Xiaowei; Paiella, Roberto

2016-06-13

Flexible photonic-crystal cavities in the form of Si-column arrays embedded in polymeric films are developed on Ge nanomembranes using direct membrane assembly. The resulting devices can sustain large biaxial tensile strain under mechanical stress, as a way to enhance the Ge radiative efficiency. Pronounced emission peaks associated with photonic-crystal cavity resonances are observed in photoluminescence measurements. These results show that ultrathin nanomembrane active layers can be effectively coupled to an optical cavity, while still preserving their mechanical flexibility. Thus, they are promising for the development of strain-enabled Ge lasers, and more generally uniquely flexible optoelectronic devices.

GOSAT validation out standing in the field: A case study of satellite validation using the SSEC Portable Atmospheric Research Center (SPARC)

NASA Astrophysics Data System (ADS)

Wagner, T. J.; Borg, L. A.; Feltz, M.; Gero, P. J.; Knuteson, R. O.; Olson, E.

2016-12-01

The Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison has developed the SSEC Portable Atmospheric Research Center (SPARC), a mobile 11 m trailer that houses numerous in situ and ground-based remote sensing instruments. Available instrumentation includes the Atmospheric Emitted Radiance Interferometer (AERI), a hyperspectral infrared radiometer from which trace gas concentrations and profiles of temperature and water vapor can be retrieved; the High Spectral Resolution Lidar (HSRL), a multichannel lidar capable of directly retrieving profiles of optical depth and backscatter depolarization; and a Doppler lidar wind profiler. The remote instrumentation suite is complemented by surface meteorology observations and a radiosonde ground station. Collectively, these instruments enable SPARC to participate in a wide variety of field studies, including meteorological field experiments and ground-based satellite calibration and validation studies. In August 2016, SPARC traveled to the Chequamegon National Forest in northern Wisconsin for a two week long deployment alongside the WLEF-TV tower. This 447 m tower houses long-term observations of thermodynamic and atmospheric composition at multiple heights, enabling studies of phenomena like atmospheric/land surface interactions and carbon uptake. During this deployment, SPARC launched radiosondes coincident with clear-sky overpasses of the Greenhouse gases Observing SATellite (GOSAT). Thermodynamic profiles from the radiosondes and AERI combined with the trace gas observations from the tower were used to validate the GOSAT observations of carbon dioxide and methane. The on-site presence of SPARC allowed for better characterization of the environment and greater observational certainty than was possible with the tower alone. Examples from this particular validation study as well as a discussion of how SPARC can contribute to other satellite calibration and validation investigations will be presented.

Engagement of neural circuits underlying 2D spatial navigation in a rodent virtual reality system.

PubMed

Aronov, Dmitriy; Tank, David W

2014-10-22

Virtual reality (VR) enables precise control of an animal's environment and otherwise impossible experimental manipulations. Neural activity in rodents has been studied on virtual 1D tracks. However, 2D navigation imposes additional requirements, such as the processing of head direction and environment boundaries, and it is unknown whether the neural circuits underlying 2D representations can be sufficiently engaged in VR. We implemented a VR setup for rats, including software and large-scale electrophysiology, that supports 2D navigation by allowing rotation and walking in any direction. The entorhinal-hippocampal circuit, including place, head direction, and grid cells, showed 2D activity patterns similar to those in the real world. Furthermore, border cells were observed, and hippocampal remapping was driven by environment shape, suggesting functional processing of virtual boundaries. These results illustrate that 2D spatial representations can be engaged by visual and rotational vestibular stimuli alone and suggest a novel VR tool for studying rat navigation.

Altruistic learning.

PubMed

Seymour, Ben; Yoshida, Wako; Dolan, Ray

2009-01-01

The origin of altruism remains one of the most enduring puzzles of human behaviour. Indeed, true altruism is often thought either not to exist, or to arise merely as a miscalculation of otherwise selfish behaviour. In this paper, we argue that altruism emerges directly from the way in which distinct human decision-making systems learn about rewards. Using insights provided by neurobiological accounts of human decision-making, we suggest that reinforcement learning in game-theoretic social interactions (habitisation over either individuals or games) and observational learning (either imitative of inference based) lead to altruistic behaviour. This arises not only as a result of computational efficiency in the face of processing complexity, but as a direct consequence of optimal inference in the face of uncertainty. Critically, we argue that the fact that evolutionary pressure acts not over the object of learning ('what' is learned), but over the learning systems themselves ('how' things are learned), enables the evolution of altruism despite the direct threat posed by free-riders.

Initiation, adherence, and retention in a randomized controlled trial of directly administered antiretroviral therapy.

PubMed

Maru, Duncan Smith-Rohrberg; Bruce, R Douglas; Walton, Mary; Mezger, Jo Anne; Springer, Sandra A; Shield, David; Altice, Frederick L

2008-03-01

Directly administered antiretroviral therapy (DAART) can improve health outcomes among HIV-infected drug users. An understanding of the utilization of DAART-initiation, adherence, and retention-is critical to successful program design. Here, we use the Behavioral Model to assess the enabling, predisposing, and need factors impacting adherence in our randomized, controlled trial of DAART versus self-administered therapy (SAT) among 141 HIV-infected drug users. Of 88 participants randomized to DAART, 74 (84%) initiated treatment, and 51 (69%) of those who initiated were retained in the program throughout the entire six-month period. Mean adherence to directly observed visits was 73%, and the mean overall composite adherence score was 77%. These results were seen despite the finding that 75% of participants indicated that they would prefer to take their own medications. Major causes of DAART discontinuation included hospitalization, incarceration, and entry into drug-treatment programs. The presence of depression and the lack of willingness to travel greater than four blocks to receive DAART predicted time-to-discontinuation.

Initiation, Adherence, and Retention in a Randomized Controlled Trial of Directly Administered Antiretroviral Therapy

PubMed Central

Maru, Duncan Smith-Rohrberg; Bruce, R. Douglas; Walton, Mary; Mezger, Jo Anne; Springer, Sandra A.; Shield, David

2009-01-01

Directly administered antiretroviral therapy (DAART) can improve health outcomes among HIV-infected drug users. An understanding of the utilization of DAART—initiation, adherence, and retention—is critical to successful program design. Here, we use the Behavioral Model to assess the enabling, predisposing, and need factors impacting adherence in our randomized, controlled trial of DAART versus self-administered therapy (SAT) among 141 HIV-infected drug users. Of 88 participants randomized to DAART, 74 (84%) initiated treatment, and 51 (69%) of those who initiated were retained in the program throughout the entire six-month period. Mean adherence to directly observed visits was 73%, and the mean overall composite adherence score was 77%. These results were seen despite the finding that 75% of participants indicated that they would prefer to take their own medications. Major causes of DAART discontinuation included hospitalization, incarceration, and entry into drug-treatment programs. The presence of depression and the lack of willingness to travel greater than four blocks to receive DAART predicted time-to-discontinuation. PMID:18085432

Pre-market approval and post-market direct-to-consumer advertising of medical devices in Australia: a case study of breast cancer screening and diagnostic devices.

PubMed

Vreugdenburg, T D; Willis, C D; Mundy, L; Hiller, J E

2013-01-01

While research investigating direct-to-consumer advertising of therapeutic goods in Australia has historically focused on prescription medicines, recent action taken by regulators against companies promoting medical devices has placed the industry into the spotlight. Despite the need to effectively regulate direct-to-consumer advertising of medical devices due to its potential harms, inadequacies in the current regulatory system have been noted. Under the present system, devices with a questionable evidence base may enter the Australian marketplace without an evaluation of their effectiveness, and regulators are reliant on industry self-regulation and consumer complaints to draw attention to cases of advertising misconduct. Although some successes in the present system have been observed, we argue that the outlined inadequacies continue to enable the promotion of medical devices to consumers without thorough or sufficient examination of evidence. © 2011 The Authors; Internal Medicine Journal © 2011 Royal Australasian College of Physicians.

Primate archaeology reveals cultural transmission in wild chimpanzees (Pan troglodytes verus).

PubMed

Luncz, Lydia V; Wittig, Roman M; Boesch, Christophe

2015-11-19

Recovering evidence of past human activities enables us to recreate behaviour where direct observations are missing. Here, we apply archaeological methods to further investigate cultural transmission processes in percussive tool use among neighbouring chimpanzee communities in the Taï National Park, Côte d'Ivoire, West Africa. Differences in the selection of nut-cracking tools between neighbouring groups are maintained over time, despite frequent female transfer, which leads to persistent cultural diversity between chimpanzee groups. Through the recovery of used tools in the suggested natal territory of immigrants, we have been able to reconstruct the tool material selection of females prior to migration. In combination with direct observations of tool selection of local residents and immigrants after migration, we uncovered temporal changes in tool selection for immigrating females. After controlling for ecological differences between territories of immigrants and residents our data suggest that immigrants abandoned their previous tool preference and adopted the pattern of their new community, despite previous personal proficiency of the same foraging task. Our study adds to the growing body of knowledge on the importance of conformist tendencies in animals. © 2015 The Author(s).

Two Populations of SiO Masers in the Galactic Bulge

NASA Astrophysics Data System (ADS)

Trapp, Adam; Rich, Robert Michael; Morris, Mark; Pihlstrom, Ylva; Sjouwerman, Lorant; Claussen, Mark J.; Stroh, Michael

2017-01-01

We present a summary of the kinematics of stellar SiO masers observed in the direction of the galactic bulge with ALMA (885 sources), and the JVLA (2,479 sources). These objects are selected by color from the MSX point source catalog, which has given an SiO detection rate of ~70%. The presented sample, along with the ~24,000 sources still being observed and reduced, enable radial velocity measurements even in regions with extreme optical extinction. These maser stars are compared to the known bulge surveys: APOGEE (~25,000 sources), BRAVA (~8000 sources), and GIBS (~6,400 sources). We have found that BAaDE stars in the direction of the bulge exist in two subpopulations: (1) A kinematically hot population exhibiting cylindrical rotation consistent with the other bulge surveys, and (2) a kinematically cold population more consistent with a disk population. In the ALMA data, we find evidence for a -200 km/s feature at (l,b) = (-9,0), possibly the symmetric complement to a previously proposed +200 km/s feature (Nidever 2012), that we do not confirm with our data.

A draft annotation and overview of the human genome

PubMed Central

Wright, Fred A; Lemon, William J; Zhao, Wei D; Sears, Russell; Zhuo, Degen; Wang, Jian-Ping; Yang, Hee-Yung; Baer, Troy; Stredney, Don; Spitzner, Joe; Stutz, Al; Krahe, Ralf; Yuan, Bo

2001-01-01

Background The recent draft assembly of the human genome provides a unified basis for describing genomic structure and function. The draft is sufficiently accurate to provide useful annotation, enabling direct observations of previously inferred biological phenomena. Results We report here a functionally annotated human gene index placed directly on the genome. The index is based on the integration of public transcript, protein, and mapping information, supplemented with computational prediction. We describe numerous global features of the genome and examine the relationship of various genetic maps with the assembly. In addition, initial sequence analysis reveals highly ordered chromosomal landscapes associated with paralogous gene clusters and distinct functional compartments. Finally, these annotation data were synthesized to produce observations of gene density and number that accord well with historical estimates. Such a global approach had previously been described only for chromosomes 21 and 22, which together account for 2.2% of the genome. Conclusions We estimate that the genome contains 65,000-75,000 transcriptional units, with exon sequences comprising 4%. The creation of a comprehensive gene index requires the synthesis of all available computational and experimental evidence. PMID:11516338

Direct imaging of multiple planets orbiting the star HR 8799.

PubMed

Marois, Christian; Macintosh, Bruce; Barman, Travis; Zuckerman, B; Song, Inseok; Patience, Jennifer; Lafrenière, David; Doyon, René

2008-11-28

Direct imaging of exoplanetary systems is a powerful technique that can reveal Jupiter-like planets in wide orbits, can enable detailed characterization of planetary atmospheres, and is a key step toward imaging Earth-like planets. Imaging detections are challenging because of the combined effect of small angular separation and large luminosity contrast between a planet and its host star. High-contrast observations with the Keck and Gemini telescopes have revealed three planets orbiting the star HR 8799, with projected separations of 24, 38, and 68 astronomical units. Multi-epoch data show counter clockwise orbital motion for all three imaged planets. The low luminosity of the companions and the estimated age of the system imply planetary masses between 5 and 13 times that of Jupiter. This system resembles a scaled-up version of the outer portion of our solar system.

Spectrally-Narrowed Emissions from Organic Crystals Having a One-Dimensional Grating on Their Surface.

PubMed

Yamamoto, Hiroyuki; Obara, Keiji; Higashihara, Shohei; Obama, Yuki; Yamao, Takeshi; Hotta, Shu

2016-04-01

We have succeeded in directly engraving one-dimensional diffraction gratings on the surface of organic semiconducting oligomer crystals by using focused ion beam (FIB) lithography and laser ablation (LA) methods. The FIB method enabled us to shape the gratings with varying periods down to ~150 nm. With the LA method a large-area grating with a ~500-nm period was readily accessible. All the above crystals indicated spectrally-narrowed emission (SNE) lines even in the case of shallow groove depths ~2-4 nm. In particular, we definitively observed the SNE pertinent to the first-order diffraction with the crystal having the diffraction grating of a 148.3-nm average period. The present results indicate utility of the built-in gratings that can directly be fabricated on the surface of the crystals.

Imaging sequential dehydrogenation of methanol on Cu(110) with a scanning tunneling microscope.

PubMed

Kitaguchi, Y; Shiotari, A; Okuyama, H; Hatta, S; Aruga, T

2011-05-07

Adsorption of methanol and its dehydrogenation on Cu(110) were studied by using a scanning tunneling microscope (STM). Upon adsorption at 12 K, methanol preferentially forms clusters on the surface. The STM could induce dehydrogenation of methanol sequentially to methoxy and formaldehyde. This enabled us to study the binding structures of these products in a single-molecule limit. Methoxy was imaged as a pair of protrusion and depression along the [001] direction. This feature is fully consistent with the previous result that it adsorbs on the short-bridge site with the C-O axis tilted along the [001] direction. The axis was induced to flip back and forth by vibrational excitations with the STM. Two configurations were observed for formaldehyde, whose structures were proposed based on their characteristic images and motions.

Microstructure Formations in the Two-Phase Region of the Binary Peritectic Organic System TRIS-NPG

NASA Technical Reports Server (NTRS)

Mogeritsch, Johann; Ludwig, Andreas

2012-01-01

In order to prepare for an onboard experiment on the International Space Station (ISS), systematic directional solidification experiments with transparent hypoperitectic alloys were carried out at different solidification rates around the critical velocity for morphological stability of both solid phases. The investigations were done in the peritectic region of the binary transparent organic TRIS-NPG system where the formation of layered structures is expected to occur. The transparent appearance of the liquid and solid phase enables real time observations of the dynamic of pattern formation during solidification. The investigations show that frequently occurring nucleation events govern the peritectic solidification morphology which occurs at the limit of morphological stability. As a consequence, banded structures lead to coupled growth even if the lateral growth is much faster compared to the growth in pulling direction.

Direct observation of two-step crystallization in nanoparticle superlattice formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Jungwon; Zheng, Haimei; Lee, Won Chul

2011-10-06

Direct imaging of nanoparticle solutions by liquid phase transmission electron microscopy has enabled unique in-situ studies of nanoparticle motion and growth. In the present work, we report on real-time formation of two-dimensional nanoparticle arrays in the very low diffusive limit, where nanoparticles are mainly driven by capillary forces and solvent fluctuations. We find that superlattice formation appears to be segregated into multiple regimes. Initially, the solvent front drags the nanoparticles, condensing them into an amorphous agglomerate. Subsequently, the nanoparticle crystallization into an array is driven by local fluctuations. Following the crystallization event, superlattice growth can also occur via the additionmore » of individual nanoparticles drawn from outlying regions by different solvent fronts. The dragging mechanism is consistent with simulations based on a coarse-grained lattice gas model at the same limit.« less

High speed direct imaging of thin metal film ablation by movie-mode dynamic transmission electron microscopy

PubMed Central

Hihath, Sahar; Santala, Melissa K.; Cen, Xi; Campbell, Geoffrey; van Benthem, Klaus

2016-01-01

Obliteration of matter by pulsed laser beams is not only prevalent in science fiction movies, but finds numerous technological applications ranging from additive manufacturing over machining of micro- and nanostructured features to health care. Pulse lengths ranging from femtoseconds to nanoseconds are utilized at varying laser beam energies and pulse lengths, and enable the removal of nanometric volumes of material. While the mechanisms for removal of material by laser irradiation, i.e., laser ablation, are well understood on the micrometer length scale, it was previously impossible to directly observe obliteration processes on smaller scales due to experimental limitations for the combination of nanometer spatial and nanosecond temporal resolution. Here, we report the direct observation of metal thin film ablation from a solid substrate through dynamic transmission electron microscopy. Quantitative analysis reveals liquid-phase dewetting of the thin-film, followed by hydrodynamic sputtering of nano- to submicron sized metal droplets. We discovered unexpected fracturing of the substrate due to evolving thermal stresses. This study confirms that hydrodynamic sputtering remains a valid mechanism for droplet expulsion on the nanoscale, while irradiation induced stress fields represent limit laser processing of nanostructured materials. Our results allow for improved safety during laser ablation in manufacturing and medical applications. PMID:26965073

High speed direct imaging of thin metal film ablation by movie-mode dynamic transmission electron microscopy

DOE PAGES

Hihath, Sahar; Santala, Melissa K.; Cen, Xi; ...

2016-03-11

Obliteration of matter by pulsed laser beams is not only prevalent in science fiction movies, but finds numerous technological applications ranging from additive manufacturing over machining of micro- and nanostructured features to health care. Pulse lengths ranging from femtoseconds to nanoseconds are utilized at varying laser beam energies and pulse lengths, and enable the removal of nanometric volumes of material. While the mechanisms for removal of material by laser irradiation, i.e., laser ablation, are well understood on the micrometer length scale, it was previously impossible to directly observe obliteration processes on smaller scales due to experimental limitations for the combinationmore » of nanometer spatial and nanosecond temporal resolution. Here, we report the direct observation of metal thin film ablation from a solid substrate through dynamic transmission electron microscopy. Quantitative analysis reveals liquid-phase dewetting of the thin-film, followed by hydrodynamic sputtering of nano- to submicron sized metal droplets. We discovered unexpected fracturing of the substrate due to evolving thermal stresses. This study confirms that hydrodynamic sputtering remains a valid mechanism for droplet expulsion on the nanoscale, while irradiation induced stress fields represent limit laser processing of nanostructured materials. Ultimately, our results allow for improved safety during laser ablation in manufacturing and medical applications.« less

Contrasting outcomes of species- and community-level analyses of the temporal consistency of functional composition.

PubMed

Katabuchi, Masatoshi; Wright, S Joseph; Swenson, Nathan G; Feeley, Kenneth J; Condit, Richard; Hubbell, Stephen P; Davies, Stuart J

2017-09-01

Multiple anthropogenic drivers affect every natural community, and there is broad interest in using functional traits to understand and predict the consequences for future biodiversity. There is, however, no consensus regarding the choice of analytical methods. We contrast species- and community-level analyses of change in the functional composition for four traits related to drought tolerance using three decades of repeat censuses of trees in the 50-ha Forest Dynamics Plot on Barro Colorado Island, Panama. Community trait distributions shifted significantly through time, which may indicate a shift toward more drought tolerant species. However, at the species level, changes in abundance were unrelated to trait values. To reconcile these seemingly contrasting results, we evaluated species-specific contributions to the directional shifts observed at the community level. Abundance changes of just one to six of 312 species were responsible for the community-level shifts observed for each trait. Our results demonstrate that directional changes in community-level functional composition can result from idiosyncratic change in a few species rather than widespread community-wide changes associated with functional traits. Future analyses of directional change in natural communities should combine community-, species-, and possibly individual-level analyses to uncover relationships with function that can improve understanding and enable prediction. © 2017 by the Ecological Society of America.

High speed direct imaging of thin metal film ablation by movie-mode dynamic transmission electron microscopy

NASA Astrophysics Data System (ADS)

Hihath, Sahar; Santala, Melissa K.; Cen, Xi; Campbell, Geoffrey; van Benthem, Klaus

2016-03-01

Obliteration of matter by pulsed laser beams is not only prevalent in science fiction movies, but finds numerous technological applications ranging from additive manufacturing over machining of micro- and nanostructured features to health care. Pulse lengths ranging from femtoseconds to nanoseconds are utilized at varying laser beam energies and pulse lengths, and enable the removal of nanometric volumes of material. While the mechanisms for removal of material by laser irradiation, i.e., laser ablation, are well understood on the micrometer length scale, it was previously impossible to directly observe obliteration processes on smaller scales due to experimental limitations for the combination of nanometer spatial and nanosecond temporal resolution. Here, we report the direct observation of metal thin film ablation from a solid substrate through dynamic transmission electron microscopy. Quantitative analysis reveals liquid-phase dewetting of the thin-film, followed by hydrodynamic sputtering of nano- to submicron sized metal droplets. We discovered unexpected fracturing of the substrate due to evolving thermal stresses. This study confirms that hydrodynamic sputtering remains a valid mechanism for droplet expulsion on the nanoscale, while irradiation induced stress fields represent limit laser processing of nanostructured materials. Our results allow for improved safety during laser ablation in manufacturing and medical applications.

Atmospheric boundary layer effects induced by the 20 March 2015 solar eclipse

NASA Astrophysics Data System (ADS)

Gray, Suzanne L.; Harrison, R. Giles

2016-04-01

The British Isles benefits from dense meteorological observation networks, enabling insights into the still-unresolved effects of solar eclipse events on the near-surface wind field. The near-surface effects of the solar eclipse of 20 March 2015 are derived through comparison of output from the Met Office's operational weather forecast model (which is ignorant of the eclipse) with data from two meteorological networks: the Met Office's land surface station (MIDAS) network and a roadside measurement network operated by Vaisala. Synoptic-evolution relative calculations reveal the cooling and increase in relative humidity almost universally attributed to eclipse events. In addition, a slackening of wind speeds by up to about 2 knots in already weak winds and backing in wind direction of about 20 degrees under clear skies across middle England are attributed to the eclipse event. The slackening of wind speed is consistent with the previously reported boundary layer stabilisation during eclipse events. Wind direction changes have previously been attributed to a large-scale `eclipse-induced cold-cored cyclone', mountain slope flows, and changes in the strength of sea breezes. A new explanation is proposed here by analogy with nocturnal wind changes at sunset and shown to predict direction changes consistent with those observed.

High speed direct imaging of thin metal film ablation by movie-mode dynamic transmission electron microscopy.

PubMed

Hihath, Sahar; Santala, Melissa K; Cen, Xi; Campbell, Geoffrey; van Benthem, Klaus

2016-03-11

Obliteration of matter by pulsed laser beams is not only prevalent in science fiction movies, but finds numerous technological applications ranging from additive manufacturing over machining of micro- and nanostructured features to health care. Pulse lengths ranging from femtoseconds to nanoseconds are utilized at varying laser beam energies and pulse lengths, and enable the removal of nanometric volumes of material. While the mechanisms for removal of material by laser irradiation, i.e., laser ablation, are well understood on the micrometer length scale, it was previously impossible to directly observe obliteration processes on smaller scales due to experimental limitations for the combination of nanometer spatial and nanosecond temporal resolution. Here, we report the direct observation of metal thin film ablation from a solid substrate through dynamic transmission electron microscopy. Quantitative analysis reveals liquid-phase dewetting of the thin-film, followed by hydrodynamic sputtering of nano- to submicron sized metal droplets. We discovered unexpected fracturing of the substrate due to evolving thermal stresses. This study confirms that hydrodynamic sputtering remains a valid mechanism for droplet expulsion on the nanoscale, while irradiation induced stress fields represent limit laser processing of nanostructured materials. Our results allow for improved safety during laser ablation in manufacturing and medical applications.

Cross-Shelf Exchange.

PubMed

Brink, K H

2016-01-01

Cross-shelf exchange dominates the pathways and rates by which nutrients, biota, and materials on the continental shelf are delivered and removed. This follows because cross-shelf gradients of most properties are usually far greater than those in the alongshore direction. The resulting transports are limited by Earth's rotation, which inhibits flow from crossing isobaths. Thus, cross-shelf flows are generally weak compared with alongshore flows, and this leads to interesting observational issues. Cross-shelf flows are enabled by turbulent mixing processes, nonlinear processes (such as momentum advection), and time dependence. Thus, there is a wide range of possible effects that can allow these critical transports, and different natural settings are often governed by different combinations of processes. This review discusses examples of representative transport mechanisms and explores possible observational and theoretical paths to future progress.

Dipolar resonances in conductive carbon micro-fibers probed by near-field terahertz spectroscopy

DOE PAGES

Khromova, I.; Navarro-Cia, M.; Brener, I.; ...

2015-07-13

In this study, we observe dipole resonances in thin conductive carbon micro-fibers by detecting an enhanced electric field in the near-field of a single fiber at terahertz (THz) frequencies. Time-domain analysis of the electric field shows that each fiber sustains resonant current oscillations at the frequency defined by the fiber's length. Strong dependence of the observed resonance frequency and degree of field enhancement on the fibers' conductive properties enable direct non-contact probing of the THz conductivity in single carbon micro-fibers. We find the conductivity of the fibers to be within the range of 1– 5∙10 4 S/m. This approach ismore » suitable for experimental characterization of individual doped semiconductor resonators for THz metamaterials and devices.« less

Evaluation of coded aperture radiation detectors using a Bayesian approach

NASA Astrophysics Data System (ADS)

Miller, Kyle; Huggins, Peter; Labov, Simon; Nelson, Karl; Dubrawski, Artur

2016-12-01

We investigate tradeoffs arising from the use of coded aperture gamma-ray spectrometry to detect and localize sources of harmful radiation in the presence of noisy background. Using an example application scenario of area monitoring and search, we empirically evaluate weakly supervised spectral, spatial, and hybrid spatio-spectral algorithms for scoring individual observations, and two alternative methods of fusing evidence obtained from multiple observations. Results of our experiments confirm the intuition that directional information provided by spectrometers masked with coded aperture enables gains in source localization accuracy, but at the expense of reduced probability of detection. Losses in detection performance can however be to a substantial extent reclaimed by using our new spatial and spatio-spectral scoring methods which rely on realistic assumptions regarding masking and its impact on measured photon distributions.

Water Cycle Extremes: from Observations to Decisions

NASA Astrophysics Data System (ADS)

Lawford, R. G.; Unninayar, S.; Berod, D.

2015-12-01

Extremes in the water cycle (droughts and floods) pose major challenges for water resource managers and emergency services. These challenges arise from observational and prediction systems, advisory services, impact reduction strategies, and cleanup and recovery operations. The Group on Earth Observations (GEO) through its Water Strategy ("GEOSS Water Strategy: from observations to decisions") is seeking to provide systems that will enable its members to more effectively meet their information needs prior to and during an extreme event. This presentation reviews the wide range of impacts that arise from extremes in the water cycle and the types of data and information needed to plan for and respond to these extreme events. It identifies the capabilities and limitations of current observational and analysis systems in defining the scale, timing, intensity and impacts of water cycle extremes and in directing society's response to them. This summary represents an early preliminary assessment of the global and regional information needs of water resource managers and begins to outline a strategy within GEO for using Earth Observations and ancillary information to address these needs.

A direct electron detector for time-resolved MeV electron microscopy

DOE PAGES

Vecchione, T.; Denes, P.; Jobe, R. K.; ...

2017-03-15

The introduction of direct electron detectors enabled the structural biology revolution of cryogenic electron microscopy. Direct electron detectors are now expected to have a similarly dramatic impact on time-resolved MeV electron microscopy, particularly by enabling both spatial and temporal jitter correction. Here in this paper, we report on the commissioning of a direct electron detector for time-resolved MeV electron microscopy. The direct electron detector demonstrated MeV single electron sensitivity and is capable of recording megapixel images at 180 Hz. The detector has a 15-bit dynamic range, better than 30-μm spatial resolution and less than 20 analogue-to-digital converter count RMS pixelmore » noise. The unique capabilities of the direct electron detector and the data analysis required to take advantage of these capabilities are presented. The technical challenges associated with generating and processing large amounts of data are also discussed.« less

A direct electron detector for time-resolved MeV electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vecchione, T.; Denes, P.; Jobe, R. K.

The introduction of direct electron detectors enabled the structural biology revolution of cryogenic electron microscopy. Direct electron detectors are now expected to have a similarly dramatic impact on time-resolved MeV electron microscopy, particularly by enabling both spatial and temporal jitter correction. Here we report on the commissioning of a direct electron detector for time-resolved MeV electron microscopy. The direct electron detector demonstrated MeV single electron sensitivity and is capable of recording megapixel images at 180 Hz. The detector has a 15-bit dynamic range, better than 30-μmμm spatial resolution and less than 20 analogue-to-digital converter count RMS pixel noise. The uniquemore » capabilities of the direct electron detector and the data analysis required to take advantage of these capabilities are presented. The technical challenges associated with generating and processing large amounts of data are also discussed.« less

A direct electron detector for time-resolved MeV electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vecchione, T.; Denes, P.; Jobe, R. K.

The introduction of direct electron detectors enabled the structural biology revolution of cryogenic electron microscopy. Direct electron detectors are now expected to have a similarly dramatic impact on time-resolved MeV electron microscopy, particularly by enabling both spatial and temporal jitter correction. Here in this paper, we report on the commissioning of a direct electron detector for time-resolved MeV electron microscopy. The direct electron detector demonstrated MeV single electron sensitivity and is capable of recording megapixel images at 180 Hz. The detector has a 15-bit dynamic range, better than 30-μm spatial resolution and less than 20 analogue-to-digital converter count RMS pixelmore » noise. The unique capabilities of the direct electron detector and the data analysis required to take advantage of these capabilities are presented. The technical challenges associated with generating and processing large amounts of data are also discussed.« less

The Publicly Available Prebiotic Interstellar Molecular Survey (primos): Expanding Spectroscopic Characterizations, Extending to New Sources, and Adding to the Known Molecular Inventory

NASA Astrophysics Data System (ADS)

McGuire, Brett A.; Carroll, P. Brandon; Corby, Joanna F.; Loomis, Ryan A.; Blake, Geoffrey A.; Hollis, Jan M.; Lovas, Frank J.; Jewell, Philip R.; Remijan, Anthony J.

2013-06-01

The publicly available Green Bank Telescope PRebiotic Interstellar MOlecular Survey (PRIMOS) conducted towards Sgr B2(N) provides high resolution, high-sensitivity observations with near-continuous frequency coverage from ˜300 MHz - 50 GHz. Of the eleven new molecular detections in the last year, five (45%) are a direct result of the PRIMOS observations. Further, these observations have recently been used to detect the predicted, but previously unobserved, J = 1-0 and J=2-1 transitions of the newly detected l-C_3H^+ ion. Here, we discuss the analysis of these transitions, as well as recent work to extend the PRIMOS observations to three new regions of interest: VY Canis Majoris, IRC+10216, and NGC 2023. Finally, we highlight the utility of cm-wave surveys in new molecular detections, as well as the value of publicly-available surveys in the approaching era of data-enabled, analysis-limited astrochemistry.

A gravitational-wave standard siren measurement of the Hubble constant

DOE PAGES

Abbott, B. P.; Abbott, R.; Abbott, T. D.; ...

2017-10-16

On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817—a strong signal from the merger of a binary neutron-star system. Less than two seconds after the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO–Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identificationof an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first ‘multi-messenger’ astronomical observation. Such observationsmore » enable GW170817 to be used as a ‘standard siren’ (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic ‘distance ladder’: the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. Furthermore, this value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision.« less

A gravitational-wave standard siren measurement of the Hubble constant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abbott, B. P.; Abbott, R.; Abbott, T. D.

On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817—a strong signal from the merger of a binary neutron-star system. Less than two seconds after the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO–Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identificationof an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first ‘multi-messenger’ astronomical observation. Such observationsmore » enable GW170817 to be used as a ‘standard siren’ (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic ‘distance ladder’: the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. Furthermore, this value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision.« less

Improved spectral comparisons of paleoclimate models and observations via proxy system modeling: Implications for multi-decadal variability

NASA Astrophysics Data System (ADS)

Dee, S. G.; Parsons, L. A.; Loope, G. R.; Overpeck, J. T.; Ault, T. R.; Emile-Geay, J.

2017-10-01

The spectral characteristics of paleoclimate observations spanning the last millennium suggest the presence of significant low-frequency (multi-decadal to centennial scale) variability in the climate system. Since this low-frequency climate variability is critical for climate predictions on societally-relevant scales, it is essential to establish whether General Circulation models (GCMs) are able to simulate it faithfully. Recent studies find large discrepancies between models and paleoclimate data at low frequencies, prompting concerns surrounding the ability of GCMs to predict long-term, high-magnitude variability under greenhouse forcing (Laepple and Huybers, 2014a, 2014b). However, efforts to ground climate model simulations directly in paleoclimate observations are impeded by fundamental differences between models and the proxy data: proxy systems often record a multivariate and/or nonlinear response to climate, precluding a direct comparison to GCM output. In this paper we bridge this gap via a forward proxy modeling approach, coupled to an isotope-enabled GCM. This allows us to disentangle the various contributions to signals embedded in ice cores, speleothem calcite, coral aragonite, tree-ring width, and tree-ring cellulose. The paper addresses the following questions: (1) do forward-modeled ;pseudoproxies; exhibit variability comparable to proxy data? (2) if not, which processes alter the shape of the spectrum of simulated climate variability, and are these processes broadly distinguishable from climate? We apply our method to representative case studies, and broaden these insights with an analysis of the PAGES2k database (PAGES2K Consortium, 2013). We find that current proxy system models (PSMs) can help resolve model-data discrepancies on interannual to decadal timescales, but cannot account for the mismatch in variance on multi-decadal to centennial timescales. We conclude that, specific to this set of PSMs and isotope-enabled model, the paleoclimate record may exhibit larger low-frequency variability than GCMs currently simulate, indicative of incomplete physics and/or forcings.

Observing the formation of ice and organic crystals in active sites

PubMed Central

Campbell, James M.; Meldrum, Fiona C.; Christenson, Hugo K.

2017-01-01

Heterogeneous nucleation is vital to a wide range of areas as diverse as ice nucleation on atmospheric aerosols and the fabrication of high-performance thin films. There is excellent evidence that surface topography is a key factor in directing crystallization in real systems; however, the mechanisms by which nanoscale pits and pores promote nucleation remain unclear. Here, we use natural cleavage defects on Muscovite mica to investigate the activity of topographical features in the nucleation from vapor of ice and various organic crystals. Direct observation of crystallization within surface pockets using optical microscopy and also interferometry demonstrates that these sharply acute features provide extremely effective nucleation sites and allows us to determine the mechanism by which this occurs. A confined phase is first seen to form along the apex of the wedge and then grows out of the pocket opening to generate a bulk crystal after a threshold saturation has been achieved. Ice nucleation proceeds in a comparable manner, although our resolution is insufficient to directly observe a condensate before the growth of a bulk crystal. These results provide insight into the mechanism of crystal deposition from vapor on real surfaces, where this will ultimately enable us to use topography to control crystal deposition on surfaces. They are also particularly relevant to our understanding of processes such as cirrus cloud formation, where such topographical features are likely candidates for the “active sites” that make clay particles effective nucleants for ice in the atmosphere. PMID:27994140

Solid-state lithium battery

DOEpatents

Ihlefeld, Jon; Clem, Paul G; Edney, Cynthia; Ingersoll, David; Nagasubramanian, Ganesan; Fenton, Kyle Ross

2014-11-04

The present invention is directed to a higher power, thin film lithium-ion electrolyte on a metallic substrate, enabling mass-produced solid-state lithium batteries. High-temperature thermodynamic equilibrium processing enables co-firing of oxides and base metals, providing a means to integrate the crystalline, lithium-stable, fast lithium-ion conductor lanthanum lithium tantalate (La.sub.1/3-xLi.sub.3xTaO.sub.3) directly with a thin metal foil current collector appropriate for a lithium-free solid-state battery.

Starshade Assembly Enabled by the Deep Space Gateway Architecture

NASA Astrophysics Data System (ADS)

Grunsfeld, J. M.; Siegler, N.; Mukherjee, R.

2018-02-01

A starshade is a large external coronagraph which will allow the direct imaging and analysis of planets around nearby stars. We present how the Deep Space Gateway would enable the robotic/astronaut construction of a starshade.

Ground-Based Lidar Measurements During the CALIPSO and Twilight Zone (CATZ) Campaign

NASA Technical Reports Server (NTRS)

Berkoff, Timothy; Qian, Li; Kleidman, Richard; Stewart, Sebastian; Welton, Ellsworth; Li, Zhu; Holbem, Brent

2008-01-01

The CALIPSO and Twilight Zone (CATZ) field campaign was carried out between June 26th and August 29th of 2007 in the multi-state Maryland-Virginia-Pennsylvania region of the U.S. to study aerosol properties and cloud-aerosol interactions during overpasses of the CALIPSO satellite. Field work was conducted on selected days when CALIPSO ground tracks occurred in the region. Ground-based measurements included data from multiple Cimel sunphotometers that were placed at intervals along a segment of the CALIPSO ground-track. These measurements provided sky radiance and AOD measurements to enable joints inversions and comparisons with CALIPSO retrievals. As part of this activity, four ground-based lidars provided backscatter measurements (at 523 nm) in the region. Lidars at University of Maryland Baltimore County (Catonsville, MD) and Goddard Space Flight Center (Greenbelt, MD) provided continuous data during the campaign, while two micro-pulse lidar (MPL) systems were temporarily stationed at various field locations directly on CALIPSO ground-tracks. As a result, thirteen on-track ground-based lidar observations were obtained from eight different locations in the region. In some cases, nighttime CALIPSO coincident measurements were also obtained. In most studies reported to date, ground-based lidar validation efforts for CALIPSO rely on systems that are at fixed locations some distance away from the satellite ground-track. The CATZ ground-based lidar data provide an opportunity to examine vertical structure properties of aerosols and clouds both on and off-track simultaneously during a CALIPSO overpass. A table of available ground-based lidar measurements during this campaign will be presented, along with example backscatter imagery for a number of coincident cases with CALIPSO. Results indicate that even for a ground-based measurements directly on-track, comparisons can still pose a challenge due to the differing spatio-temporal properties of the ground and satellite observations. The multiple-lidar data during the CATZ campaign is expected to provide additional information on regional aerosol and cloud dynamics for give overpass, and enable a more realistic assessment of ground-to-satellite correlations. Future work is anticipated to finalize calibrated lidar backscatter profiles and utilization of wind trajectory information to further enable comparisons to CALIPS data.

Direct fabrication of graphene on SiO2 enabled by thin film stress engineering.

PubMed

McNerny, Daniel Q; Viswanath, B; Copic, Davor; Laye, Fabrice R; Prohoda, Christophor; Brieland-Shoultz, Anna C; Polsen, Erik S; Dee, Nicholas T; Veerasamy, Vijayen S; Hart, A John

2014-05-23

We demonstrate direct production of graphene on SiO2 by CVD growth of graphene at the interface between a Ni film and the SiO2 substrate, followed by dry mechanical delamination of the Ni using adhesive tape. This result is enabled by understanding of the competition between stress evolution and microstructure development upon annealing of the Ni prior to the graphene growth step. When the Ni film remains adherent after graphene growth, the balance between residual stress and adhesion governs the ability to mechanically remove the Ni after the CVD process. In this study the graphene on SiO2 comprises micron-scale domains, ranging from monolayer to multilayer. The graphene has >90% coverage across centimeter-scale dimensions, limited by the size of our CVD chamber. Further engineering of the Ni film microstructure and stress state could enable manufacturing of highly uniform interfacial graphene followed by clean mechanical delamination over practically indefinite dimensions. Moreover, our findings suggest that preferential adhesion can enable production of 2-D materials directly on application-relevant substrates. This is attractive compared to transfer methods, which can cause mechanical damage and leave residues behind.

Direct fabrication of graphene on SiO2 enabled by thin film stress engineering

PubMed Central

McNerny, Daniel Q.; Viswanath, B.; Copic, Davor; Laye, Fabrice R.; Prohoda, Christophor; Brieland-Shoultz, Anna C.; Polsen, Erik S.; Dee, Nicholas T.; Veerasamy, Vijayen S.; Hart, A. John

2014-01-01

We demonstrate direct production of graphene on SiO2 by CVD growth of graphene at the interface between a Ni film and the SiO2 substrate, followed by dry mechanical delamination of the Ni using adhesive tape. This result is enabled by understanding of the competition between stress evolution and microstructure development upon annealing of the Ni prior to the graphene growth step. When the Ni film remains adherent after graphene growth, the balance between residual stress and adhesion governs the ability to mechanically remove the Ni after the CVD process. In this study the graphene on SiO2 comprises micron-scale domains, ranging from monolayer to multilayer. The graphene has >90% coverage across centimeter-scale dimensions, limited by the size of our CVD chamber. Further engineering of the Ni film microstructure and stress state could enable manufacturing of highly uniform interfacial graphene followed by clean mechanical delamination over practically indefinite dimensions. Moreover, our findings suggest that preferential adhesion can enable production of 2-D materials directly on application-relevant substrates. This is attractive compared to transfer methods, which can cause mechanical damage and leave residues behind. PMID:24854632

Direct imaging and spectroscopy of habitable planets using JWST and a starshade

NASA Astrophysics Data System (ADS)

Soummer, Rémi; Valenti, Jeff; Brown, Robert A.; Seager, Sara; Tumlinson, Jason; Cash, Webster; Jordan, Ian; Postman, Marc; Mountain, Matt; Glassman, Tiffany; Pueyo, Laurent; Roberge, Aki

2010-07-01

A starshade with the James Webb Space Telescope (JWST) is the only possible path forward in the next decade to obtain images and spectra of a planet similar to the Earth, to study its habitability, and search for signs of alien life. While JWST was not specifically designed to observe using a starshade, its near-infrared instrumentation is in principle capable of doing so and could achieve major results in the study of terrestrialmass exoplanets. However, because of technical reasons associated with broadband starlight suppression and filter red-leak, NIRSpec would need a slight modification to one of its target acquisition filters to enable feasible observations of Earth-like planets. This upgrade would 1) retire the high risk associated with the effects of the current filter red leak which are difficult to model given the current state of knowledge on instrument stray light and line spread function at large separation angles, 2) enable access to the oxygen band at 0.76 μm in addition to the 1.26 μm band, 3) enable a smaller starshade by relaxing requirements on bandwidth and suppression 4) reduce detector saturation and associated long recovery times. The new filter would not affect neither NIRSpecs scientific performance nor its operations, but it would dramatically reduce the risk of adding a starshade to JWST in the future and enhance the performance of any starshade that is built. In combination with a starshade, JWST could be the most capable and cost effective of all the exoplanet hunting missions proposed for the next decade, including purpose built observatories for medium-size missions.

Characterization of Harmonic Signal Acquisition with Parallel Dipole and Multipole Detectors

NASA Astrophysics Data System (ADS)

Park, Sung-Gun; Anderson, Gordon A.; Bruce, James E.

2018-04-01

Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is a powerful instrument for the study of complex biological samples due to its high resolution and mass measurement accuracy. However, the relatively long signal acquisition periods needed to achieve high resolution can serve to limit applications of FTICR-MS. The use of multiple pairs of detector electrodes enables detection of harmonic frequencies present at integer multiples of the fundamental cyclotron frequency, and the obtained resolving power for a given acquisition period increases linearly with the order of harmonic signal. However, harmonic signal detection also increases spectral complexity and presents challenges for interpretation. In the present work, ICR cells with independent dipole and harmonic detection electrodes and preamplifiers are demonstrated. A benefit of this approach is the ability to independently acquire fundamental and multiple harmonic signals in parallel using the same ions under identical conditions, enabling direct comparison of achieved performance as parameters are varied. Spectra from harmonic signals showed generally higher resolving power than spectra acquired with fundamental signals and equal signal duration. In addition, the maximum observed signal to noise (S/N) ratio from harmonic signals exceeded that of fundamental signals by 50 to 100%. Finally, parallel detection of fundamental and harmonic signals enables deconvolution of overlapping harmonic signals since observed fundamental frequencies can be used to unambiguously calculate all possible harmonic frequencies. Thus, the present application of parallel fundamental and harmonic signal acquisition offers a general approach to improve utilization of harmonic signals to yield high-resolution spectra with decreased acquisition time. [Figure not available: see fulltext.

The International Solar Terrestrial Physics Program: A Model for International Cooperation in Space Research

NASA Astrophysics Data System (ADS)

Acuña, M.

The International Solar Terrestrial Physics Program (ISTP) evolved from the individual plans of US, Japanese and European countries to develop space missions to expand our knowledge of the Sun-Earth connection as a "system". Previous experience with independent missions amply illustrated the critical need for coordinated and simultaneous observations in key regions of Sun-Earth space in order to resolve time-space ambiguities and cause-effect relationships. Mission studies such as the US Origins of Plasmas in the Earth's Neighborhood (OPEN), Geotail in Japan, the Solar Heliospheric Observatory in Europe and the Regatta and other magnetospheric missions in the former Soviert Union, formed the early conceptual elements that eventually led to the ISTP program. The coordinating role developed by the Inter-Agency-Consultative-Group (IACG) integrated by NASA, ESA, ISAS and IKI and demonstrated during the comet Halley apparition in 1986, was continued to include solar-terrestrial research and the mission elements described above. In addition to the space elements, a most important component of the coordination effort was the inclusion of data networks, analysis and planning tools as well as globally accessible data sets by the scientific community at large. This approach enabled the active and direct participation of scientists in developing countries in one of the most comprehensive solar-terrestrial research programs implemented to date. The creation of multiple ISTP data repositories throughout the world has enabled a large number of scientists in developing countries to have direct access to the latest spacecraft observations and a most fruitful interaction with fellow researchers throughout the world. This paper will present a review of the evolution of the ISTP program, its products, analysis tools, data bases, infrastructure and lessons learned applicable to future international collaborative programs.

Deterministic photon-emitter coupling in chiral photonic circuits.

PubMed

Söllner, Immo; Mahmoodian, Sahand; Hansen, Sofie Lindskov; Midolo, Leonardo; Javadi, Alisa; Kiršanskė, Gabija; Pregnolato, Tommaso; El-Ella, Haitham; Lee, Eun Hye; Song, Jin Dong; Stobbe, Søren; Lodahl, Peter

2015-09-01

Engineering photon emission and scattering is central to modern photonics applications ranging from light harvesting to quantum-information processing. To this end, nanophotonic waveguides are well suited as they confine photons to a one-dimensional geometry and thereby increase the light-matter interaction. In a regular waveguide, a quantum emitter interacts equally with photons in either of the two propagation directions. This symmetry is violated in nanophotonic structures in which non-transversal local electric-field components imply that photon emission and scattering may become directional. Here we show that the helicity of the optical transition of a quantum emitter determines the direction of single-photon emission in a specially engineered photonic-crystal waveguide. We observe single-photon emission into the waveguide with a directionality that exceeds 90% under conditions in which practically all the emitted photons are coupled to the waveguide. The chiral light-matter interaction enables deterministic and highly directional photon emission for experimentally achievable on-chip non-reciprocal photonic elements. These may serve as key building blocks for single-photon optical diodes, transistors and deterministic quantum gates. Furthermore, chiral photonic circuits allow the dissipative preparation of entangled states of multiple emitters for experimentally achievable parameters, may lead to novel topological photon states and could be applied for directional steering of light.

Deterministic photon-emitter coupling in chiral photonic circuits

NASA Astrophysics Data System (ADS)

Söllner, Immo; Mahmoodian, Sahand; Hansen, Sofie Lindskov; Midolo, Leonardo; Javadi, Alisa; Kiršanskė, Gabija; Pregnolato, Tommaso; El-Ella, Haitham; Lee, Eun Hye; Song, Jin Dong; Stobbe, Søren; Lodahl, Peter

2015-09-01

Engineering photon emission and scattering is central to modern photonics applications ranging from light harvesting to quantum-information processing. To this end, nanophotonic waveguides are well suited as they confine photons to a one-dimensional geometry and thereby increase the light-matter interaction. In a regular waveguide, a quantum emitter interacts equally with photons in either of the two propagation directions. This symmetry is violated in nanophotonic structures in which non-transversal local electric-field components imply that photon emission and scattering may become directional. Here we show that the helicity of the optical transition of a quantum emitter determines the direction of single-photon emission in a specially engineered photonic-crystal waveguide. We observe single-photon emission into the waveguide with a directionality that exceeds 90% under conditions in which practically all the emitted photons are coupled to the waveguide. The chiral light-matter interaction enables deterministic and highly directional photon emission for experimentally achievable on-chip non-reciprocal photonic elements. These may serve as key building blocks for single-photon optical diodes, transistors and deterministic quantum gates. Furthermore, chiral photonic circuits allow the dissipative preparation of entangled states of multiple emitters for experimentally achievable parameters, may lead to novel topological photon states and could be applied for directional steering of light.

Gyroscopic sensing in the wings of the hawkmoth Manduca sexta: the role of sensor location and directional sensitivity.

PubMed

Hinson, Brian T; Morgansen, Kristi A

2015-10-06

The wings of the hawkmoth Manduca sexta are lined with mechanoreceptors called campaniform sensilla that encode wing deformations. During flight, the wings deform in response to a variety of stimuli, including inertial-elastic loads due to the wing flapping motion, aerodynamic loads, and exogenous inertial loads transmitted by disturbances. Because the wings are actuated, flexible structures, the strain-sensitive campaniform sensilla are capable of detecting inertial rotations and accelerations, allowing the wings to serve not only as a primary actuator, but also as a gyroscopic sensor for flight control. We study the gyroscopic sensing of the hawkmoth wings from a control theoretic perspective. Through the development of a low-order model of flexible wing flapping dynamics, and the use of nonlinear observability analysis, we show that the rotational acceleration inherent in wing flapping enables the wings to serve as gyroscopic sensors. We compute a measure of sensor fitness as a function of sensor location and directional sensitivity by using the simulation-based empirical observability Gramian. Our results indicate that gyroscopic information is encoded primarily through shear strain due to wing twisting, where inertial rotations cause detectable changes in pronation and supination timing and magnitude. We solve an observability-based optimal sensor placement problem to find the optimal configuration of strain sensor locations and directional sensitivities for detecting inertial rotations. The optimal sensor configuration shows parallels to the campaniform sensilla found on hawkmoth wings, with clusters of sensors near the wing root and wing tip. The optimal spatial distribution of strain directional sensitivity provides a hypothesis for how heterogeneity of campaniform sensilla may be distributed.

Tongue-driven sonar beam steering by a lingual-echolocating fruit bat

PubMed Central

Falk, Benjamin; Chiu, Chen; Krishnan, Anand; Arbour, Jessica H.; Moss, Cynthia F.

2017-01-01

Animals enhance sensory acquisition from a specific direction by movements of head, ears, or eyes. As active sensing animals, echolocating bats also aim their directional sonar beam to selectively “illuminate” a confined volume of space, facilitating efficient information processing by reducing echo interference and clutter. Such sonar beam control is generally achieved by head movements or shape changes of the sound-emitting mouth or nose. However, lingual-echolocating Egyptian fruit bats, Rousettus aegyptiacus, which produce sound by clicking their tongue, can dramatically change beam direction at very short temporal intervals without visible morphological changes. The mechanism supporting this capability has remained a mystery. Here, we measured signals from free-flying Egyptian fruit bats and discovered a systematic angular sweep of beam focus across increasing frequency. This unusual signal structure has not been observed in other animals and cannot be explained by the conventional and widely-used “piston model” that describes the emission pattern of other bat species. Through modeling, we show that the observed beam features can be captured by an array of tongue-driven sound sources located along the side of the mouth, and that the sonar beam direction can be steered parsimoniously by inducing changes to the pattern of phase differences through moving tongue location. The effects are broadly similar to those found in a phased array—an engineering design widely found in human-made sonar systems that enables beam direction changes without changes in the physical transducer assembly. Our study reveals an intriguing parallel between biology and human engineering in solving problems in fundamentally similar ways. PMID:29244805

Tongue-driven sonar beam steering by a lingual-echolocating fruit bat.

PubMed

Lee, Wu-Jung; Falk, Benjamin; Chiu, Chen; Krishnan, Anand; Arbour, Jessica H; Moss, Cynthia F

2017-12-01

Animals enhance sensory acquisition from a specific direction by movements of head, ears, or eyes. As active sensing animals, echolocating bats also aim their directional sonar beam to selectively "illuminate" a confined volume of space, facilitating efficient information processing by reducing echo interference and clutter. Such sonar beam control is generally achieved by head movements or shape changes of the sound-emitting mouth or nose. However, lingual-echolocating Egyptian fruit bats, Rousettus aegyptiacus, which produce sound by clicking their tongue, can dramatically change beam direction at very short temporal intervals without visible morphological changes. The mechanism supporting this capability has remained a mystery. Here, we measured signals from free-flying Egyptian fruit bats and discovered a systematic angular sweep of beam focus across increasing frequency. This unusual signal structure has not been observed in other animals and cannot be explained by the conventional and widely-used "piston model" that describes the emission pattern of other bat species. Through modeling, we show that the observed beam features can be captured by an array of tongue-driven sound sources located along the side of the mouth, and that the sonar beam direction can be steered parsimoniously by inducing changes to the pattern of phase differences through moving tongue location. The effects are broadly similar to those found in a phased array-an engineering design widely found in human-made sonar systems that enables beam direction changes without changes in the physical transducer assembly. Our study reveals an intriguing parallel between biology and human engineering in solving problems in fundamentally similar ways.

The nanoaquarium: A nanofluidic platform for in situ transmission electron microscopy in liquid media

NASA Astrophysics Data System (ADS)

Grogan, Joseph M.

There are many scientifically interesting and technologically relevant nanoscale phenomena that take place in liquid media. Examples include aggregation and assembly of nanoparticles; colloidal crystal formation; liquid phase growth of structures such as nanowires; electrochemical deposition and etching for fabrication processes and battery applications; interfacial phenomena; boiling and cavitation; and biological interactions. Understanding of these fields would benefit greatly from real-time, in situ transmission electron microscope (TEM) imaging with nanoscale resolution. Most liquids cannot be imaged by traditional TEM due to evaporation in the high vacuum environment and the requirement that samples be very thin. Liquid-cell in situ TEM has emerged as an exciting new experimental technique that hermetically seals a thin slice of liquid between two electron transparent membranes to enable TEM imaging of liquid-based processes. This work presents details of the fabrication of a custom-made liquid-cell in situ TEM device, dubbed the nanoaquarium. The nanoaquarium's highlights include an exceptionally thin sample cross section (10s to 100s of nm); wafer scale processing that enables high-yield mass production; robust hermetic sealing that provides leak-free operation without use of glue, epoxy, or any polymers; compatibility with lab-on-chip technology; and on-chip integrated electrodes for sensing and actuation. The fabrication process is described, with an emphasis on direct wafer bonding. Experimental results involving direct observation of colloid aggregation using an aqueous solution of gold nanoparticles are presented. Quantitative analysis of the growth process agrees with prior results and theory, indicating that the experimental technique does not radically alter the observed phenomenon. For the first time, in situ observations of nanoparticles at a contact line and in an evaporating thin film of liquid are reported, with applications for techniques such as dip-coating and drop-casting, commonly used for depositing nanoparticles on a surface via convective-capillary assembly. Theoretical analysis suggests that the observed particle motion and aggregation are caused by gradients in surface tension and disjoining pressure in the thin liquid film.

Automated Quantification of Arbitrary Arm-Segment Structure in Spiral Galaxies

NASA Astrophysics Data System (ADS)

Davis, Darren Robert

This thesis describes a system that, given approximately-centered images of spiral galaxies, produces quantitative descriptions of spiral galaxy structure without the need for per-image human input. This structure information consists of a list of spiral arm segments, each associated with a fitted logarithmic spiral arc and a pixel region. This list-of-arcs representation allows description of arbitrary spiral galaxy structure: the arms do not need to be symmetric, may have forks or bends, and, more generally, may be arranged in any manner with a consistent spiral-pattern center (non-merging galaxies have a sufficiently well-defined center). Such flexibility is important in order to accommodate the myriad structure variations observed in spiral galaxies. From the arcs produced from our method it is possible to calculate measures of spiral galaxy structure such as winding direction, winding tightness, arm counts, asymmetry, or other values of interest (including user-defined measures). In addition to providing information about the spiral arm "skeleton" of each galaxy, our method can enable analyses of brightness within individual spiral arms, since we provide the pixel regions associated with each spiral arm segment. For winding direction, arm tightness, and arm count, comparable information is available (to various extents) from previous efforts; to the extent that such information is available, we find strong correspondence with our output. We also characterize the changes to (and invariances in) our output as a function of modifications to important algorithm parameters. By enabling generation of extensive data about spiral galaxy structure from large-scale sky surveys, our method will enable new discoveries and tests regarding the nature of galaxies and the universe, and will facilitate subsequent work to automatically fit detailed brightness models of spiral galaxies.

Optical barcoding of PLGA for multispectral analysis of nanoparticle fate in vivo.

PubMed

Medina, David X; Householder, Kyle T; Ceton, Ricki; Kovalik, Tina; Heffernan, John M; Shankar, Rohini V; Bowser, Robert P; Wechsler-Reya, Robert J; Sirianni, Rachael W

2017-05-10

Understanding of the mechanisms by which systemically administered nanoparticles achieve delivery across biological barriers remains incomplete, due in part to the challenge of tracking nanoparticle fate in the body. Here, we develop a new approach for "barcoding" nanoparticles composed of poly(lactic-co-glycolic acid) (PLGA) with bright, spectrally defined quantum dots (QDs) to enable direct, fluorescent detection of nanoparticle fate with subcellular resolution. We show that QD labeling does not affect major biophysical properties of nanoparticles or their interaction with cells and tissues. Live cell imaging enabled simultaneous visualization of the interaction of control and targeted nanoparticles with bEnd.3 cells in a flow chamber, providing direct evidence that surface modification of nanoparticles with the cell-penetrating peptide TAT increases their biophysical association with cell surfaces over very short time periods under convective current. We next developed this technique for quantitative biodistribution analysis in vivo. These studies demonstrate that nanoparticle surface modification with the cell penetrating peptide TAT facilitates brain-specific delivery that is restricted to brain vasculature. Although nanoparticle entry into the healthy brain parenchyma is minimal, with no evidence for movement of nanoparticles across the blood-brain barrier (BBB), we observed that nanoparticles are able to enter to the central nervous system (CNS) through regions of altered BBB permeability - for example, into circumventricular organs in the brain or leaky vasculature of late-stage intracranial tumors. In sum, these data demonstrate a new, multispectral approach for barcoding PLGA, which enables simultaneous, quantitative analysis of the fate of multiple nanoparticle formulations in vivo. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Compartmentalized microchannel array for high-throughput analysis of single cell polarized growth and dynamics

DOE PAGES

Geng, Tao; Bredeweg, Erin L.; Szymanski, Craig J.; ...

2015-11-04

Here, interrogating polarized growth is technologically challenging due to extensive cellular branching and uncontrollable environmental conditions in conventional assays. Here we present a robust and high-performance microfluidic system that enables observations of polarized growth with enhanced temporal and spatial control over prolonged periods. The system has built-in tunability and versatility to accommodate a variety of science applications requiring precisely controlled environments. Using the model filamentous fungus, Neurospora crassa, this microfluidic system enabled direct visualization and analysis of cellular heterogeneity in a clonal fungal cell population, nuclear distribution and dynamics at the subhyphal level, and quantitative dynamics of gene expression withmore » single hyphal compartment resolution in response to carbon source starvation and exchange experiments. Although the microfluidic device is demonstrated on filamentous fungi, our technology is immediately extensible to a wide array of other biosystems that exhibit similar polarized cell growth with applications ranging from bioenergy production to human health.« less

Electromagnetic Design of Feedhorn-Coupled Transition-Edge Sensors for Cosmic Microwave Background Polarimetery

NASA Technical Reports Server (NTRS)

Chuss, David T.

2011-01-01

Observations of the cosmic microwave background (CMB) provide a powerful tool for probing the evolution of the early universe. Specifically, precision measurement of the polarization of the CMB enables a direct test for cosmic inflation. A key technological element on the path to the measurement of this faint signal is the capability to produce large format arrays of background-limited detectors. We describe the electromagnetic design of feedhorn-coupled, TES-based sensors. Each linear orthogonal polarization from the feed horn is coupled to a superconducting microstrip line via a symmetric planar orthomode transducer (OMT). The symmetric OMT design allows for highly-symmetric beams with low cross-polarization over a wide bandwidth. In addition, this architecture enables a single microstrip filter to define the passband for each polarization. Care has been taken in the design to eliminate stray coupling paths to the absorbers. These detectors will be fielded in the Cosmology Large Angular Scale Surveyor (CLASS).

Photoacoustic microscopy of cerebral hemodynamic and oxygen-metabolic responses to anesthetics

NASA Astrophysics Data System (ADS)

Cao, Rui; Li, Jun; Ning, Bo; Sun, Naidi; Wang, Tianxiong; Zuo, Zhiyi; Hu, Song

2017-02-01

General anesthetics are known to have profound effects on cerebral hemodynamics and neuronal activities. However, it remains a challenge to directly assess anesthetics-induced hemodynamic and oxygen-metabolic changes from the true baseline under wakefulness at the microscopic level, due to the lack of an enabling technology for high-resolution functional imaging of the awake mouse brain. To address this challenge, we have developed head-restrained photoacoustic microscopy (PAM), which enables simultaneous imaging of the cerebrovascular anatomy, total concentration and oxygen saturation of hemoglobin (CHb and sO2), and blood flow in awake mice. From these hemodynamic measurements, two important metabolic parameters, oxygen extraction fraction (OEF) and the cerebral metabolic rate of oxygen (CMRO2), can be derived. Side-by-side comparison of the mouse brain under wakefulness and anesthesia revealed multifaceted cerebral responses to isoflurane, a volatile anesthetic widely used in preclinical research and clinical practice. Key observations include elevated cerebral blood flow (CBF) and reduced oxygen extraction and metabolism.

Coupling between diffusion and orientation of pentacene molecules on an organic surface.

PubMed

Rotter, Paul; Lechner, Barbara A J; Morherr, Antonia; Chisnall, David M; Ward, David J; Jardine, Andrew P; Ellis, John; Allison, William; Eckhardt, Bruno; Witte, Gregor

2016-04-01

The realization of efficient organic electronic devices requires the controlled preparation of molecular thin films and heterostructures. As top-down structuring methods such as lithography cannot be applied to van der Waals bound materials, surface diffusion becomes a structure-determining factor that requires microscopic understanding. Scanning probe techniques provide atomic resolution, but are limited to observations of slow movements, and therefore constrained to low temperatures. In contrast, the helium-3 spin-echo (HeSE) technique achieves spatial and time resolution on the nm and ps scale, respectively, thus enabling measurements at elevated temperatures. Here we use HeSE to unveil the intricate motion of pentacene admolecules diffusing on a chemisorbed monolayer of pentacene on Cu(110) that serves as a stable, well-ordered organic model surface. We find that pentacene moves along rails parallel and perpendicular to the surface molecules. The experimental data are explained by admolecule rotation that enables a switching between diffusion directions, which extends our molecular level understanding of diffusion in complex organic systems.

A new light on caloric test--what was disclosed by three dimensional analysis of caloric nystagmus?

NASA Technical Reports Server (NTRS)

Arai, Y.

2001-01-01

For better understanding of caloric nystagmus, this phenomenon will be reviewed historically in three stages. 1) The first light on caloric nystagmus was thrown by Barany 1906. Through direct observation of eye movements, Barany established the caloric test as an important tool to determine the side of lesion for vertigo. 2) The second light is shed by electrooculogram (EOG) from the late 1950th. EOG enabled qualitative analysis of caloric nystagmus, and proved Barany's convection theory, but resulted in neglect of vertical and roll eye movements. 3) The third light is gained by 3D recording of eye movements started from the late 1980th. 3D recordings of eye movements enabled us to analyze the spatial orientation of caloric nystagmus, and disclose the close correlation of the nystagmus components in the head vertical and the space vertical planes, suggesting a contribution of the velocity storage integrator. The 3D property of caloric nystagmus will be explained in detail.

Simultaneous observations of ice motion, calving and seismicity on the Yahtse Glacier, Alaska. (Invited)

NASA Astrophysics Data System (ADS)

Larsen, C. F.; Bartholomaus, T. C.; O'Neel, S.; West, M. E.

2010-12-01

We observe ice motion, calving and seismicity simultaneously and with high-resolution on an advancing tidewater glacier in Icy Bay, Alaska. Icy Bay’s tidewater glaciers dominate regional glacier-generated seismicity in Alaska. Yahtse emanates from the St. Elias Range near the Bering-Bagley-Seward-Malaspina Icefield system, the most extensive glacier cover outside the polar regions. Rapid rates of change and fast flow (>16 m/d near the terminus) at Yahtse Glacier provide a direct analog to the disintegrating outlet systems in Greenland. Our field experiment co-locates GPS and seismometers on the surface of the glacier, with a greater network of bedrock seismometers surrounding the glacier. Time-lapse photogrammetry, fjord wave height sensors, and optical survey methods monitor iceberg calving and ice velocity near the terminus. This suite of geophysical instrumentation enables us to characterize glacier motion and geometry changes while concurrently listening for seismic energy release. We are performing a close examination of calving as a seismic source, and the associated mechanisms of energy transfer to seismic waves. Detailed observations of ice motion (GPS and optical surveying), glacier geometry and iceberg calving (direct observations and timelapse photogrammetry) have been made in concert with a passive seismic network. Combined, the observations form the basis of a rigorous analysis exploring the relationship between glacier-generated seismic events and motion, glacier-fiord interactions, calving and hydraulics. Our work is designed to demonstrate the applicability and utility of seismology to study the impact of climate forcing on calving glaciers.

An Analysis of Fundamental Waffle Mode in Early AEOS Adaptive Optics Images

NASA Astrophysics Data System (ADS)

Makidon, Russell B.; Sivaramakrishnan, Anand; Perrin, Marshall D.; Roberts, Lewis C., Jr.; Oppenheimer, Ben R.; Soummer, Rémi; Graham, James R.

2005-08-01

Adaptive optics (AO) systems have significantly improved astronomical imaging capabilities over the last decade and are revolutionizing the kinds of science possible with 4-5 m class ground-based telescopes. A thorough understanding of AO system performance at the telescope can enable new frontiers of science as observations push AO systems to their performance limits. We look at recent advances with wave-front reconstruction (WFR) on the Advanced Electro-Optical System (AEOS) 3.6 m telescope to show how progress made in improving WFR can be measured directly in improved science images. We describe how a ``waffle mode'' wave-front error (which is not sensed by a Fried geometry Shack-Hartmann wave-front sensor) affects the AO point-spread function. We model details of AEOS AO to simulate a PSF that matches the actual AO PSF in the I band and show that while the older observed AEOS PSF contained several times more waffle error than expected, improved WFR techniques noticeably improve AEOS AO performance. We estimate the impact of these improved WFRs on H-band imaging at AEOS, chosen based on the optimization of the Lyot Project near-infrared coronagraph at this bandpass. Based on observations made at the Maui Space Surveillance System, operated by Detachment 15 of the US Air Force Research Laboratory's Directed Energy Directorate.

Genome-wide Selective Sweeps in Natural Bacterial Populations Revealed by Time-series Metagenomics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, Leong-Keat; Bendall, Matthew L.; Malfatti, Stephanie

2014-06-18

Multiple evolutionary models have been proposed to explain the formation of genetically and ecologically distinct bacterial groups. Time-series metagenomics enables direct observation of evolutionary processes in natural populations, and if applied over a sufficiently long time frame, this approach could capture events such as gene-specific or genome-wide selective sweeps. Direct observations of either process could help resolve how distinct groups form in natural microbial assemblages. Here, from a three-year metagenomic study of a freshwater lake, we explore changes in single nucleotide polymorphism (SNP) frequencies and patterns of gene gain and loss in populations of Chlorobiaceae and Methylophilaceae. SNP analyses revealedmore » substantial genetic heterogeneity within these populations, although the degree of heterogeneity varied considerably among closely related, co-occurring Methylophilaceae populations. SNP allele frequencies, as well as the relative abundance of certain genes, changed dramatically over time in each population. Interestingly, SNP diversity was purged at nearly every genome position in one of the Chlorobiaceae populations over the course of three years, while at the same time multiple genes either swept through or were swept from this population. These patterns were consistent with a genome-wide selective sweep, a process predicted by the ‘ecotype model’ of diversification, but not previously observed in natural populations.« less

Mapping Sub-pc Structure in AGNs with Water Vapor Megamasers

NASA Astrophysics Data System (ADS)

Braatz, James; Reid, Mark; Condon, James; Lo, K. Y.; Henkel, Christian; Kuo, Cheng-Yu; Impellizzeri, Violette; Gao, Feng; Zhao, Wei; Greene, Jenny; Constantin, Anca

2012-12-01

VLBI observations of water vapor megamasers provide the only direct means of mapping gas in AGNs on sub-parsec scales. Altogether, megamasers have been detected in about 150 galaxies, most of them nearby (z < 0.05), type 2 AGNs. Twenty one of these systems have now been mapped with VLBI. In about 25% of all maser-detected galaxies, the single-dish spectrum of the emission reveals a triple-peaked profile characteristic of masers in a thin, circumnuclear, edge-on accretion disk, and VLBI observations of these megamasers confirm the disk geometry. The maps reveal the size, shape (i.e. warp), and orientation of the disks, they provide gold-standard black hole masses and, in several cases, they enable the measurement of geometric distances to the host galaxies. In a few megamasers with more ambiguous single-dish profiles, VLBI maps show that some of the emission originates not in a disk, but rather from clouds that appear to be associated with an outflow. In these megamasers, and possibly many of the systems not yet mapped with VLBI, the masers may be directly associated with optically opaque, dusty gas believed to obscure some AGNs. Here we summarize results from VLBI imaging of megamasers and discuss the prospects for using observations of masers to understand the nature of obscuring gas in AGNs.

Genome-wide Selective Sweeps in Natural Bacterial Populations Revealed by Time-series Metagenomics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, Leong-Keat; Bendall, Matthew L.; Malfatti, Stephanie

2014-05-12

Multiple evolutionary models have been proposed to explain the formation of genetically and ecologically distinct bacterial groups. Time-series metagenomics enables direct observation of evolutionary processes in natural populations, and if applied over a sufficiently long time frame, this approach could capture events such as gene-specific or genome-wide selective sweeps. Direct observations of either process could help resolve how distinct groups form in natural microbial assemblages. Here, from a three-year metagenomic study of a freshwater lake, we explore changes in single nucleotide polymorphism (SNP) frequencies and patterns of gene gain and loss in populations of Chlorobiaceae and Methylophilaceae. SNP analyses revealedmore » substantial genetic heterogeneity within these populations, although the degree of heterogeneity varied considerably among closely related, co-occurring Methylophilaceae populations. SNP allele frequencies, as well as the relative abundance of certain genes, changed dramatically over time in each population. Interestingly, SNP diversity was purged at nearly every genome position in one of the Chlorobiaceae populations over the course of three years, while at the same time multiple genes either swept through or were swept from this population. These patterns were consistent with a genome-wide selective sweep, a process predicted by the ecotype model? of diversification, but not previously observed in natural populations.« less

The impact of services that offer individualised funds, shared management, person-centred relationships, and self-direction on the lived experiences of consumers with mental illness.

PubMed

Peterson, Sunila; Buchanan, Angus; Falkmer, Torbjorn

2014-01-01

Mental health service providers across Australia, including Western Australia (WA), have begun to offer individualised funds, shared management, person-centred and self-directed (SPS) services. No research exists on the impact of SPS services on the lived experiences of these particular consumers. This study explored the impact of a SPS service offered for the first time in WA to consumers with mental illness. Data on sixteen consumers' lived experiences were analysed using an abbreviated grounded theory approach. These data had been developed by the consumers, Guides (staff) and an independent evaluator, and most of it had been collected in the past prior to the commencement of the study. Three over-arching categories, and related subcategories, emerged indicating that 1) access to individualised funds enabled practical and psychological benefits to consumers; 2) consistent contact in shared management and person-centred relationships enhanced the provision of timely and meaningful staff support to consumers; and 3) high quality shared management and person-centred relationships with staff and the opportunity to self-direct enabled consumers' change and growth. SPS services enhanced consumers' lived experiences and enabled staff to provide and consumers to experience timely access to recovery resources, consistent contact, responsive and high quality support, and self-direction of services. In this, consumers changed, grew and achieved desired recovery experiences. The overall impact of the SPS service seemed to be founded on the goodness of fit between person characteristics of staff and consumers, which enabled rich support that provided for corrective emotional experiences. This enabled consumers to build meaningful and hopeful lives where they started to live with, and beyond, their mental illness.

IC 3639—a New Bona Fide Compton-Thick AGN Unveiled by NuSTAR

NASA Astrophysics Data System (ADS)

Boorman, Peter G.; Gandhi, P.; Alexander, D. M.; Annuar, A.; Ballantyne, D. R.; Bauer, F.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Farrah, D.; Hailey, C. J.; Harrison, F. A.; Hönig, S. F.; Koss, M.; LaMassa, S. M.; Masini, A.; Ricci, C.; Risaliti, G.; Stern, D.; Zhang, W. W.

2016-12-01

We analyze high-quality NuSTAR observations of the local (z = 0.011) Seyfert 2 active galactic nucleus (AGN) IC 3639, in conjunction with archival Suzaku and Chandra data. This provides the first broadband X-ray spectral analysis of the source, spanning nearly two decades in energy (0.5-30 keV). Previous X-ray observations of the source below 10 keV indicated strong reflection/obscuration on the basis of a pronounced iron fluorescence line at 6.4 keV. The hard X-ray energy coverage of NuSTAR, together with self-consistent toroidal reprocessing models, enables direct broadband constraints on the obscuring column density of the source. We find the source to be heavily Compton-thick (CTK) with an obscuring column in excess of 3.6× {10}24 cm-2, unconstrained at the upper end. We further find an intrinsic 2-10 keV luminosity of {{log}}10({L}2{--10{keV}} [{erg} {{{s}}}-1])={43.4}-1.1+0.6 to 90% confidence, almost 400 times the observed flux, and consistent with various multiwavelength diagnostics. Such a high ratio of intrinsic to observed flux, in addition to an Fe-Kα fluorescence line equivalent width exceeding 2 keV, is extreme among known bona fide CTK AGNs, which we suggest are both due to the high level of obscuration present around IC 3639. Our study demonstrates that broadband spectroscopic modeling with NuSTAR enables large corrections for obscuration to be carried out robustly and emphasizes the need for improved modeling of AGN tori showing intense iron fluorescence.

Method for reworkable packaging of high speed, low electrical parasitic power electronics modules through gate drive integration

DOEpatents

Passmore, Brandon; Cole, Zach; Whitaker, Bret; Barkley, Adam; McNutt, Ty; Lostetter, Alexander

2016-08-02

A multichip power module directly connecting the busboard to a printed-circuit board that is attached to the power substrate enabling extremely low loop inductance for extreme environments such as high temperature operation. Wire bond interconnections are taught from the power die directly to the busboard further enabling enable low parasitic interconnections. Integration of on-board high frequency bus capacitors provide extremely low loop inductance. An extreme environment gate driver board allows close physical proximity of gate driver and power stage to reduce overall volume and reduce impedance in the control circuit. Parallel spring-loaded pin gate driver PCB connections allows a reliable and reworkable power module to gate driver interconnections.

Penalized spline estimation for functional coefficient regression models.

PubMed

Cao, Yanrong; Lin, Haiqun; Wu, Tracy Z; Yu, Yan

2010-04-01

The functional coefficient regression models assume that the regression coefficients vary with some "threshold" variable, providing appreciable flexibility in capturing the underlying dynamics in data and avoiding the so-called "curse of dimensionality" in multivariate nonparametric estimation. We first investigate the estimation, inference, and forecasting for the functional coefficient regression models with dependent observations via penalized splines. The P-spline approach, as a direct ridge regression shrinkage type global smoothing method, is computationally efficient and stable. With established fixed-knot asymptotics, inference is readily available. Exact inference can be obtained for fixed smoothing parameter λ, which is most appealing for finite samples. Our penalized spline approach gives an explicit model expression, which also enables multi-step-ahead forecasting via simulations. Furthermore, we examine different methods of choosing the important smoothing parameter λ: modified multi-fold cross-validation (MCV), generalized cross-validation (GCV), and an extension of empirical bias bandwidth selection (EBBS) to P-splines. In addition, we implement smoothing parameter selection using mixed model framework through restricted maximum likelihood (REML) for P-spline functional coefficient regression models with independent observations. The P-spline approach also easily allows different smoothness for different functional coefficients, which is enabled by assigning different penalty λ accordingly. We demonstrate the proposed approach by both simulation examples and a real data application.

Impairment of prosocial sentiments is associated with frontopolar and septal damage in frontotemporal dementia

PubMed Central

Moll, Jorge; Zahn, Roland; de Oliveira-Souza, Ricardo; Bramati, Ivanei E.; Krueger, Frank; Tura, Bernardo; Cavanagh, Alyson L.; Grafman, Jordan

2010-01-01

Poets and philosophers have long acknowledged moral sentiments as key motivators of human social behavior. Prosocial sentiments, which include guilt, pity and embarrassment, enable us to care about others and to be concerned about our mistakes. Functional imaging studies have implicated frontopolar, ventromedial frontal and basal forebrain regions in the experience of prosocial sentiments. Patients with lesions of the frontopolar and ventromedial frontal areas were observed to behave inappropriately and less prosocially, which could be attributed to a generalized emotional blunting. Direct experimental evidence for brain regions distinctively associated with moral sentiment impairments is lacking, however. We investigated this issue in patients with the behavioral variant of frontotemporal dementia, a disorder in which early and selective impairments of social conduct are consistently observed. Using a novel moral sentiment task, we show that the degree of impairment of prosocial sentiments is associated with the degree of damage to frontopolar cortex and septal area, as assessed with 18-Fluoro-Deoxy-Glucose-Positron Emission Tomography, an established measure of neurodegenerative damage. This effect was dissociable from impairment of other-critical feelings (anger and disgust), which was in turn associated with dorsomedial prefrontal and amygdala dysfunction. Our findings suggest a critical role of the frontopolar cortex and septal region in enabling prosocial sentiments, a fundamental component of moral conscience. PMID:20728544

Finger-Shaped GelForce: Sensor for Measuring Surface Traction Fields for Robotic Hand.

PubMed

Sato, K; Kamiyama, K; Kawakami, N; Tachi, S

2010-01-01

It is believed that the use of haptic sensors to measure the magnitude, direction, and distribution of a force will enable a robotic hand to perform dexterous operations. Therefore, we develop a new type of finger-shaped haptic sensor using GelForce technology. GelForce is a vision-based sensor that can be used to measure the distribution of force vectors, or surface traction fields. The simple structure of the GelForce enables us to develop a compact finger-shaped GelForce for the robotic hand. GelForce that is developed on the basis of an elastic theory can be used to calculate surface traction fields using a conversion equation. However, this conversion equation cannot be analytically solved when the elastic body of the sensor has a complicated shape such as the shape of a finger. Therefore, we propose an observational method and construct a prototype of the finger-shaped GelForce. By using this prototype, we evaluate the basic performance of the finger-shaped GelForce. Then, we conduct a field test by performing grasping operations using a robotic hand. The results of this test show that using the observational method, the finger-shaped GelForce can be successfully used in a robotic hand.

Interlayer Exciton Optoelectronics in a 2D Heterostructure p-n Junction.

PubMed

Ross, Jason S; Rivera, Pasqual; Schaibley, John; Lee-Wong, Eric; Yu, Hongyi; Taniguchi, Takashi; Watanabe, Kenji; Yan, Jiaqiang; Mandrus, David; Cobden, David; Yao, Wang; Xu, Xiaodong

2017-02-08

Semiconductor heterostructures are backbones for solid-state-based optoelectronic devices. Recent advances in assembly techniques for van der Waals heterostructures have enabled the band engineering of semiconductor heterojunctions for atomically thin optoelectronic devices. In two-dimensional heterostructures with type II band alignment, interlayer excitons, where Coulomb bound electrons and holes are confined to opposite layers, have shown promising properties for novel excitonic devices, including a large binding energy, micron-scale in-plane drift-diffusion, and a long population and valley polarization lifetime. Here, we demonstrate interlayer exciton optoelectronics based on electrostatically defined lateral p-n junctions in a MoSe 2 -WSe 2 heterobilayer. Applying a forward bias enables the first observation of electroluminescence from interlayer excitons. At zero bias, the p-n junction functions as a highly sensitive photodetector, where the wavelength-dependent photocurrent measurement allows the direct observation of resonant optical excitation of the interlayer exciton. The resulting photocurrent amplitude from the interlayer exciton is about 200 times smaller than the resonant excitation of intralayer exciton. This implies that the interlayer exciton oscillator strength is 2 orders of magnitude smaller than that of the intralayer exciton due to the spatial separation of electron and hole to the opposite layers. These results lay the foundation for exploiting the interlayer exciton in future 2D heterostructure optoelectronic devices.

Magnetoelastoelectric coupling in core-shell nanoparticles enabling directional and mode-selective magnetic control of THz beam propagation

DOE PAGES

Dutta, Moumita; Prasankumar, Rohit Prativadi; Natarajan, Kamaraju; ...

2017-08-07

Magnetoelastoelectric coupling in an engineered biphasic multiferroic nanocomposite enables a novel magnetic field direction-defined propagation control of terahertz (THz) waves. These core–shell nanoparticles are comprised of a ferromagnetic cobalt ferrite core and a ferroelectric barium titanate shell. Furthermore, an assembly of these nanoparticles, when operated in external magnetic fields, exhibits a controllable amplitude modulation when the magnetic field is applied antiparallel to the THz wave propagation direction; yet the same assembly displays an additional phase modulation when the magnetic field is applied along the propagation direction. And while field-induced magnetostriction of the core leads to amplitude modulation, phase modulation ismore » a result of stress-mediated piezoelectricity of the outer ferroelectric shell.« less

Envisioning a Future of Computational Geoscience in a Data Rich Semantic World

NASA Astrophysics Data System (ADS)

Kumar, P.; Elag, M.; Jiang, P.; Marini, L.

2015-12-01

Advances in observational systems and reduction in their cost are allowing us to explore, monitor, and digitally represent our environment in unprecedented details and over large areas. Low cost in situ sensors, unmanned autonomous vehicles, imaging technologies, and other new observational approaches along with airborne and space borne systems are allowing us to measure nearly everything, almost everywhere, and at almost all the time. Under the aegis of observatories they are enabling an integrated view across space and time scales ranging from storms to seasons to years and, in some cases, decades. Rapid increase in the convergence of computational, communication and information systems and their inter-operability through advances in technologies such as semantic web can provide opportunities to further facilitate fusion and synthesis of heterogeneous measurements with knowledge systems. This integration can enable us to break disciplinary boundaries and bring sensor data directly to desktop or handheld devices. We describe CyberInfrastructure effort that is being developed through projects such as Earthcube Geosemantics (http://geosemantics.hydrocomplexity.net), (SEAD (http://sead-data.net/), and Browndog (http://browndog.ncsa.illinois.edu/)s o that data across all of earth science can be easily shared and integrated with models. This also includes efforts to enable models to become interoperable among themselves and with data using technologies that enable human-out-of-the-loop integration. Through such technologies our ability to use real time information for decision-making and scientific investigations will increase multifold. The data goes through a sequence of steps, often iterative, from collection to long-term preservation. Similarly the scientific investigation and associated outcomes are composed of a number of iterative steps from problem identification to solutions. However, the integration between these two pathways is rather limited. We describe characteristics of new technologies that are needed to bring these processes together in the near future to significantly reduce the latency between data, science, and agile and informed actions that support sustainability.

Direct observation of electrothermal instability structures on intensely Ohmically heated aluminum with current flowing in a surface skin layer

NASA Astrophysics Data System (ADS)

Awe, Thomas

2017-10-01

Implosions on the Z Facility assemble high-energy-density plasmas for radiation effects and ICF experiments, but achievable stagnation pressures and temperatures are degraded by the Magneto-Rayleigh-Taylor (MRT) instability. While the beryllium liners (tubes) used in Magnetized Liner Inertial Fusion (MagLIF) experiments are astonishingly smooth (10 to 50 nm RMS roughness), they also contain distributed micron-scale resistive inclusions, and large MRT amplitudes are observed. Early in the implosion, an electrothermal instability (ETI) may provide a perturbation which greatly exceeds the initial surface roughness of the liner. Resistive inhomogeneities drive nonuniform current density and Joule heating, resulting in locally higher temperature, and thus still higher resistivity. Such unstable temperature and pressure growth produce density perturbations which seed MRT. For MagLIF liners, ETI seeding of MRT has been inferred by evaluating late-time MRT, but a direct observation of ETI is not made. ETI is directly observed on the surface of 1.0-mm-diameter solid Al rods pulsed to 1 MA in 100 ns via high resolution gated optical imaging (2 ns temporal and 3 micron spatial resolution). Aluminum 6061 alloy rods, with micron-scale resistive inclusions, consistently first demonstrate overheating from distinct, 10-micron-scale, sub-eV spots, which 5-10 ns later merge into azimuthally stretched elliptical spots and discrete strata (40-100 microns wide by 10 microns tall). Axial plasma filaments form shortly thereafter. Surface plasma can be suppressed for rods coated with dielectric, enabling extended study of the evolution of stratified ETI structures, and experimental inference of ETI growth rates. This fundamentally new and highly 3-dimensional dataset informs ETI physics, including when the ETI seed of MRT may be initiated.

Crust-mantle coupling mechanism in Cameroon, West Africa, revealed by 3D S-wave velocity and azimuthal anisotropy

NASA Astrophysics Data System (ADS)

Ojo, Adebayo Oluwaseun; Ni, Sidao; Chen, Haopeng; Xie, Jun

2018-01-01

To understand the depth variation of deformation beneath Cameroon, West Africa, we developed a new 3D model of S-wave isotropic velocity and azimuthal anisotropy from joint analysis of ambient seismic noise and earthquake surface wave dispersion. We found that the Cameroon Volcanic Line (CVL) is well delineated by slow phase velocities in contrast with the neighboring Congo Craton, in agreement with previous studies. Apart from the Congo Craton and the Oubanguides Belt, the uppermost mantle revealed a relatively slow velocity indicating a thinned or thermally altered lithosphere. The direction of fast axis in the upper crust is mostly NE-SW, but trending approximately N-S around Mt. Oku and the southern CVL. The observed crustal azimuthal anisotropy is attributed to alignment of cracks and crustal deformation related to magmatic activities. A widespread zone of weak-to-zero azimuthal anisotropy in the mid-lower crust shows evidence for vertical mantle flow or isotropic mid-lower crust. In the uppermost mantle, the fast axis direction changed from NE-SW to NW-SE around Mt. Oku and northern Cameroon. This suggests a layered mechanism of deformation and revealed that the mantle lithosphere has been deformed. NE-SW fast azimuths are observed beneath the Congo Craton and are consistent with the absolute motion of the African plate, suggesting a mantle origin for the observed azimuthal anisotropy. Our tomographically derived fast directions are consistent with the local SKS splitting results in some locations and depths, enabling us to constrain the origin of the observed splitting. The different feature of azimuthal anisotropy in the upper crust and the uppermost mantle implies decoupling between deformation of crust and mantle in Cameroon.

Near-Infrared Polarimetric Imaging of Disks around Young Intermediate-mass Stars in SEEDS

NASA Astrophysics Data System (ADS)

Fukagawa, Misato; Hashimoto, Jun; Grady, C. A.; Momose, Munetake; Wisniewski, J. P.; Okamoto, Yoshiko; Muto, Takayuki; Kusakabe, Nobuhiko; Bonnefoy, Mickael; Kotani, Takayuki; Maruta, Yayoi; Tamura, Motohide; Seeds/Hiciao/Ao188 Collaboration,

2013-07-01

We present our recent results to directly image circumstellar disks around Herbig Fe/Ae/Be stars in scattered light with Subaru. Observations of such young disks are critically important to understand how disks evolve possibly under the mutual interaction with new-born planets. One of the observational approaches is direct imaging in scattered light, and the progress in this field since PPV can be found in the ability to prove inner regions of disks. This improvement largely owes to the technique of polarization differential imaging (PDI) which provides higher contrast by extracting scattered light from the disk while suppressing unpolarized stellar light. Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS) is the project dedicated to exoplanet hunting and study of circumstellar disks by direct imaging. Since its beginning in 2009, thirteen Herbig Fe/Ae/Be stars have been observed primarily in H band (1.6 micron). The PDI method has been employed with adaptive optics, enabling us to look into the inner region as close as 0.2 arcsec (˜30 AU) in radius with the typical angular resolution of 0.06 arcsec (˜8 AU). As a result, the SEEDS imagery has newly uncovered rich structures such as spiral arms, inner holes, and gaps for (pre-)transitional disks while suggested the variably illuminated disks for primordial systems. The highlight is the discovery of two spiral arms each for SAO 206462 and MWC 758. The spiral feature has been uniquely found toward Herbig Fe/Aes so far, which might be due to their warmer disks producing arms loosely wound and more easily detected. The observed morphology can be interpreted by the density-wave model, and those disks are implied to harbor Jupiter-mass companions as the exciting sources of the spiral structures according to these models.

``Making the Molecular Movie'': First Frames

NASA Astrophysics Data System (ADS)

Miller, R. J. Dwayne

2011-03-01

Femtosecond Electron Diffraction has enabled atomic resolution to structural changes as they occur, essentially watching atoms move in real time--directly observe transition states. This experiment has been referred to as ``making the molecular movie'' and has been previously discussed in the context of a gedanken experiment. With the recent development of femtosecond electron pulses with sufficient number density to execute single shot structure determinations, this experiment has been finally realized. A new concept in electron pulse generation was developed based on a solution to the N-body electron propagation problem involving up to 10,000 interacting electrons that has led to a new generation of extremely bright electron pulsed sources that minimizes space charge broadening effects. Previously thought intractable problems of determining t=0 and fully characterizing electron pulses on the femtosecond time scale have now been solved through the use of the laser pondermotive potential to provide a time dependent scattering source. Synchronization of electron probe and laser excitation pulses is now possible with an accuracy of 10 femtoseconds to follow even the fastest nuclear motions. The camera for the ``molecular movie'' is well in hand based on high bunch charge electron sources. Several movies depicting atomic motions during passage through structural transitions will be shown. Atomic level views of the simplest possible structural transition, melting, will be presented for a number of systems in which both thermal and purely electronically driven atomic displacements can be correlated to the degree of directional bonding. Optical manipulation of charge distributions and effects on interatomic forces/bonding can be directly observed through the ensuing atomic motions. New phenomena involving strongly correlated electron systems will be presented in which an exceptionally cooperative phase transitions has been observed. The primitive origin of molecular cooperativity has also been discovered in recent studies of molecular crystals. These new developments will be discussed in the context of developing the necessary technology to directly observe the structure-function correlation in biomolecules--the fundamental molecular basis of biological systems.

Nano-enabled drug delivery: a research profile.

PubMed

Zhou, Xiao; Porter, Alan L; Robinson, Douglas K R; Shim, Min Suk; Guo, Ying

2014-07-01

Nano-enabled drug delivery (NEDD) systems are rapidly emerging as a key area for nanotechnology application. Understanding the status and developmental prospects of this area around the world is important to determine research priorities, and to evaluate and direct progress. Global research publication and patent databases provide a reservoir of information that can be tapped to provide intelligence for such needs. Here, we present a process to allow for extraction of NEDD-related information from these databases by involving topical experts. This process incorporates in-depth analysis of NEDD literature review papers to identify key subsystems and major topics. We then use these to structure global analysis of NEDD research topical trends and collaborative patterns, inform future innovation directions. This paper describes the process of how to derive nano-enabled drug delivery-related information from global research and patent databases in an effort to perform comprehensive global analysis of research trends and directions, along with collaborative patterns. Copyright © 2014 Elsevier Inc. All rights reserved.

Dictating photoreactivity through restricted bond rotations: cross-photoaddition of atropisomeric acrylimide derivatives under UV/visible-light irradiation.

PubMed

Iyer, Akila; Jockusch, Steffen; Sivaguru, J

2014-11-13

Nonbiaryl atropisomeric acrylimides underwent facile [2 + 2] photocycloaddition leading to cross-cyclobutane adducts with very high stereospecificity (enantiomeric excess (ee): 99% and diastereomeric excess (de): 99%). The photoreactions proceeded smoothly in isotropic media for both direct and triplet sensitized irradiations. The reactions were also found to be very efficient in the solid state where the same cross-cyclobutane adduct was observed. Photophysical studies enabled us to understand the excited-state photochemistry of acrylimides. The triplet energy was found to be ∼63 kcal/mol. The reactions proceeded predominantly via a singlet excited state upon direct irradiation with very poor intersystem crossing that was ascertained by quantification of the generated singlet oxygen. The reactions progressed smoothly with triplet sensitization with UV or visible-light irradiations. Laser flash photolysis experiments established the triplet transient of atropisomeric acrylimides with a triplet lifetime at room temperature of ∼40 ns.

Quantized circular photogalvanic effect in Weyl semimetals

NASA Astrophysics Data System (ADS)

de Juan, Fernando; Grushin, Adolfo G.; Morimoto, Takahiro; Moore, Joel E.

The circular photogalvanic effect (CPGE) is the part of a photocurrent that switches depending on the sense of circular polarization of the incident light. It has been consistently observed in systems without inversion symmetry and depends on non-universal material details. We find that in a class of Weyl semimetals (e.g. SrSi2) and three-dimensional Rashba materials (e.g. doped Te) without inversion and mirror symmetries, the CPGE trace is effectively Quantized in terms of the combination of fundamental constants e3/h2 cɛ0 with no material-dependent parameters. This is so because the CPGE directly measures the topological charge of Weyl points near the Fermi surface, and non-quantized corrections from disorder and additional bands can be small over a significant range of incident frequencies. Moreover, the magnitude of the CPGE induced by a Weyl node is relatively large, which enables the direct detection of the monopole charge with current techniques.

Quantized circular photogalvanic effect in Weyl semimetals

NASA Astrophysics Data System (ADS)

de Juan, Fernando; Grushin, Adolfo G.; Morimoto, Takahiro; Moore, Joel E.

2017-07-01

The circular photogalvanic effect (CPGE) is the part of a photocurrent that switches depending on the sense of circular polarization of the incident light. It has been consistently observed in systems without inversion symmetry and depends on non-universal material details. Here we find that in a class of Weyl semimetals (for example, SrSi2) and three-dimensional Rashba materials (for example, doped Te) without inversion and mirror symmetries, the injection contribution to the CPGE trace is effectively quantized in terms of the fundamental constants e, h, c and with no material-dependent parameters. This is so because the CPGE directly measures the topological charge of Weyl points, and non-quantized corrections from disorder and additional bands can be small over a significant range of incident frequencies. Moreover, the magnitude of the CPGE induced by a Weyl node is relatively large, which enables the direct detection of the monopole charge with current techniques.

Formation pathways of mesoporous silica nanoparticles with dodecagonal tiling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yao; Ma, Kai; Kao, Teresa

Considerable progress in the fabrication of quasicrystals demonstrates that they can be realized in a broad range of materials. However, the development of chemistries enabling direct experimental observation of early quasicrystal growth pathways remains challenging. Here, we report the synthesis of four surfactant-directed mesoporous silica nanoparticle structures, including dodecagonal quasicrystalline nanoparticles, as a function of micelle pore expander concentration or stirring rate. We demonstrate that the early formation stages of dodecagonal quasicrystalline mesoporous silica nanoparticles can be preserved, where precise control of mesoporous silica nanoparticle size down to <30 nm facilitates comparison between mesoporous silica nanoparticles and simulated single-particle growthmore » trajectories beginning with a single tiling unit. Our results reveal details of the building block size distributions during early growth and how they promote quasicrystal formation. This work identifies simple synthetic parameters, such as stirring rate, that may be exploited to design other quasicrystal-forming self-assembly chemistries and processes.« less

Formation pathways of mesoporous silica nanoparticles with dodecagonal tiling

DOE PAGES

Sun, Yao; Ma, Kai; Kao, Teresa; ...

2017-08-15

Considerable progress in the fabrication of quasicrystals demonstrates that they can be realized in a broad range of materials. However, the development of chemistries enabling direct experimental observation of early quasicrystal growth pathways remains challenging. Here, we report the synthesis of four surfactant-directed mesoporous silica nanoparticle structures, including dodecagonal quasicrystalline nanoparticles, as a function of micelle pore expander concentration or stirring rate. We demonstrate that the early formation stages of dodecagonal quasicrystalline mesoporous silica nanoparticles can be preserved, where precise control of mesoporous silica nanoparticle size down to <30 nm facilitates comparison between mesoporous silica nanoparticles and simulated single-particle growthmore » trajectories beginning with a single tiling unit. Our results reveal details of the building block size distributions during early growth and how they promote quasicrystal formation. This work identifies simple synthetic parameters, such as stirring rate, that may be exploited to design other quasicrystal-forming self-assembly chemistries and processes.« less

Structure and Dynamics of Dinucleosomes Assessed by Atomic Force Microscopy

DOE PAGES

Filenko, Nina A.; Palets, Dmytro B.; Lyubchenko, Yuri L.

2012-01-01

Dynamics of nucleosomes and their interactions are important for understanding the mechanism of chromatin assembly. Internucleosomal interaction is required for the formation of higher-order chromatin structures. Although H1 histone is critically involved in the process of chromatin assembly, direct internucleosomal interactions contribute to this process as well. To characterize the interactions of nucleosomes within the nucleosome array, we designed a dinucleosome and performed direct AFM imaging. The analysis of the AFM data showed dinucleosomes are very dynamic systems, enabling the nucleosomes to move in a broad range along the DNA template. Di-nucleosomes in close proximity were observed, but their populationmore » was low. The use of the zwitterionic detergent, CHAPS, increased the dynamic range of the di-nucleosome, facilitating the formation of tight di-nucleosomes. The role of CHAPS and similar natural products in chromatin structure and dynamics is also discussed.« less

Direct-access retrieval during sentence comprehension: Evidence from Sluicing

PubMed Central

Martin, Andrea E.; McElree, Brian

2011-01-01

Language comprehension requires recovering meaning from linguistic form, even when the mapping between the two is indirect. A canonical example is ellipsis, the omission of information that is subsequently understood without being overtly pronounced. Comprehension of ellipsis requires retrieval of an antecedent from memory, without prior prediction, a property which enables the study of retrieval in situ (Martin & McElree, 2008, 2009). Sluicing, or inflectional phrase ellipsis, in the presence of a conjunction, presents a test case where a competing antecedent position is syntactically licensed, in contrast with most cases of nonadjacent dependency, including verb phrase ellipsis. We present speed-accuracy tradeoff and eye-movement data inconsistent with the hypothesis that retrieval is accomplished via a syntactically guided search, a particular variant of search not examined in past research. The observed timecourse profiles are consistent with the hypothesis that antecedents are retrieved via a cue-dependent direct-access mechanism susceptible to general memory variables. PMID:21580797

High-frequency phosphorus and nitrate measurements for improved statutory water quality monitoring and management

NASA Astrophysics Data System (ADS)

Bieroza, Magdalena

2017-04-01

High-frequency nutrient (phosphorus and nitrogen) monitoring using wet-chemistry analysers and optical sensors has revolutionised the collection of biogeochemical data from streams, rivers and lakes. Matching the nutrient measurement time with timescales of hydrological responses has revealed biogeochemical patterns and nutrient hydrological responses not observed previously. Capturing a wider range of nutrient concentrations compared to traditional coarse resolution sampling enables more accurate estimation of mean concentrations and loads and thus improved water body classification. However, to date the scientific insights from the high-frequency nutrient monitoring studies have not been translated into policy and operational responses. The pertinent question is where and how often to measure nutrients to satisfy statutory monitoring requirements for the Water Framework Directive and the Nitrates Directive. Therefore this paper discusses how the reduced data uncertainty and improved process understanding obtained with the high-frequency measurements can improve statutory nutrient monitoring, using case studies from England and Sweden.

The elusive abnormal CO2 insertion enabled by metal-ligand cooperative photochemical selectivity inversion.

PubMed

Schneck, Felix; Ahrens, Jennifer; Finger, Markus; Stückl, A Claudia; Würtele, Christian; Schwarzer, Dirk; Schneider, Sven

2018-03-21

Direct hydrogenation of CO 2 to CO, the reverse water-gas shift reaction, is an attractive route to CO 2 utilization. However, the use of molecular catalysts is impeded by the general reactivity of metal hydrides with CO 2 . Insertion into M-H bonds results in formates (MO(O)CH), whereas the abnormal insertion to the hydroxycarbonyl isomer (MC(O)OH), which is the key intermediate for CO-selective catalysis, has never been directly observed. We here report that the selectivity of CO 2 insertion into a Ni-H bond can be inverted from normal to abnormal insertion upon switching from thermal to photochemical conditions. Mechanistic examination for abnormal insertion indicates photochemical N-H reductive elimination as the pivotal step that leads to an umpolung of the hydride ligand. This study conceptually introduces metal-ligand cooperation for selectivity control in photochemical transformations.

Debris Disk Structure and Morphology as Revealed by Aggressive STIS Multi-Roll Coronagraphy: A New Look at Some Old Friends

NASA Technical Reports Server (NTRS)

Grady, Carol A; Kuchner, Marc; Woodgate, Bruce E.

2012-01-01

We present new imaging results from a well-selected sample of II circumstellar debris disks, all with HST pedigree, using STIS visible-light 6-roll PSF-template subtracted coronagraphy (PSFTSC). These new observations, pushing HST to its highest levels of coronagraphic performance, simultaneously probe both the interior regions of these debris systems, with inner working distances < app 8 AU for half the stars in this sample (corresponding to the giant planet and Kuiper belt regions within our own solar system), and the exterior regions far beyond. These new images enable direct inter-comparison of the architectures of these exoplanetary debris systems in the context of our own Solar System: These observations also permit us, for the first time, to characterize material in these regions at high spatial resolution and identify disk sub-structures that are signposts of planet formation and evolution; in particular, asymmetries and non-uniform debris structures that signal the presence of co-orbiting perturbing planets, and dynamical interactions (e.g., resulting in posited small grain stripping and disk "pollution") with the ISM. We focus here on recently acquired and reduced images of he circumstellar debris systems about: AU Mic (edge-on, and @ 10 pc the closest star in our sample), HD 61005, HD 32297 and HD 15115 (all with morphologies strongly suggestive of ISM wind interactions), HD 181327 & HDI07146 (close to face-on with respectively narrow and broad debris rings), and MP Mus (a "mature" proto-planetary disk hosted by a cTTS). All of our objects were previously observed in the near-IR with inferior spatial resolution and imaging efficacy, but with NICMOS r = 0.3" inner working angle (IWA) comparable to STIS multi-roll coronagraphy. The combination of new optical and existing near-IR imaging can strongly constrain the dust properties, thus enabling an assessment of grain processing and planetesimal populations. These results will directly inform upon the posited planet formation mechanisms that occur after the approximately 10 My epoch of gas depletion, a time in our solar system when giant planets were migrating and terrestrial planets were forming, and directly test theoretical models of these processes. These observations lmiquely probe both into the interior regions of these systems and are sensitive to and spatially resolve low surface-brightness (SB) material at large stellocentric distances with spatial resolution comparable to ACS and with augmenting NICMOS near-IR disk photometry in hand.

Geodetic imaging: A new tool for Mesoamerican archaeology

NASA Astrophysics Data System (ADS)

Carter, William E.; Shrestha, Ramesh L.; Fisher, Christopher; Leisz, Stephen

2012-10-01

On 15 May 2012, Honduran President Porfirio Lobo convened a press conference to announce that researchers mapping areas of the Mosquitia region of Honduras, using airborne light detection and ranging (lidar), had discovered what appeared to be an extensive complex of archaeological ruins hidden beneath the dense canopy of rain forest that shrouds the terrain [UTL Scientific, LLC, 2012]. President Lobo released preliminary images of the ruins derived from the airborne lidar observations (Figure 1a) but withheld information about their precise location so that measures could be taken to protect and preserve this newly discovered cultural heritage. The coordinates of the ruins, determined from the lidar observations with an accuracy of a few decimeters, will enable archaeological teams to use the Global Positioning System to navigate through the dense forest directly to features of interest.

Real-space observation of strong metal-support interaction: state-of-the-art and what's the next.

PubMed

Shi, X Y; Zhang, W; Zhang, C; Zheng, W T; Chen, H; Qi, J G

2016-06-01

The real-space resolving of the encapsulated overlayer in the well-known model and industry catalysts, ascribed to the advent of dedicated transmission electron microscopy, enables us to probe novel nano/micro architecture chemistry for better application, revisiting our understanding of this key issue in heterogeneous catalysis. In this review, we summarize the latest progress of real-space observation of SMSI in several well-known systems mainly covered from the metal catalysts (mostly Pt) supported by the TiO2 , CeO2 and Fe3 O4 . As a comparison with the model catalyst Pt/Fe3 O4 , the industrial catalyst Cu/ZnO is also listed, followed with the suggested ongoing directions in the field. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Nanoaquariums Fabricated by Femtosecond Laser for Exploration of Dynamics and Functions of Microorganisms

NASA Astrophysics Data System (ADS)

Sugioka, Koji; Hanada, Yasutaka; Kawano, Hiroyuki; Ishikawa, Ikuko S.; Miyawaki, Atsushi; Midorikawa, Katsumi

2010-10-01

We demonstrate to fabricate microfluidic chips integrated with some functional elements such as optical attenuators and optical waveguides by femtosecond (fs) laser direct writing for mechanism study of gliding movement of Phormidium to a seedling root. Femtosecond laser irradiation followed by annealing and wet etching in dilute hydrofluoric (HF) acid solution resulted in formation of three-dimensional (3D) hollow microstructures embedded in a photosensitive glass. The embedded microfludic structures enabled us to easily and efficiently observe Phormidium gliding to the seedling root, which accelerates growth of the vegetable seedling. In addition, integration of optical attenuators and optical waveguides into the microfluidic structures in the microchip clarified the mechanism of the gliding movement of Phormidium. Such microchips, referred to as nanoaquariums, realized the highly efficient and functional observation and analysis of various microorganisms.

Nano-aquarium fabrication with cut-off filter for mechanism study of Phormidium assemblage

NASA Astrophysics Data System (ADS)

Hanada, Y.; Sugioka, K.; Ishikawa, I.; Kawano, H.; Miyawaki, A.; Midorikawa, K.

2010-02-01

We demonstrate fabrication of microfluidic chips integrated with different functional elements such as optical filters and optical waveguide for mechanism study of gliding movement of Phormidium to a seedling root using a femtosecond (fs) laser. Fs laser direct writing followed by annealing and successive wet etching in dilute hydrofluoric (HF) acid solution resulted in formation of three dimensional (3D) hollow microstructures embedded in a photostructurable glass. The embedded microfludic structures enabled us to easily and efficiently observe Phormidium gliding to the seedling root, which accelerates growth of the seedling. In addition, fabrication of optical filter and optical waveguide integrated with the microfluidic structures in the microchip clarified the mechanism of the gliding movement. Such microchips, referred to as a nano-aquarium, realize the efficient and highly functional observation and analysis of the gliding movement of Phormidium.

Sodium temperature/wind lidar based on laser-diode-pumped Nd:YAG lasers deployed at Tromsø, Norway (69.6°N, 19.2°E).

PubMed

Kawahara, T D; Nozawa, S; Saito, N; Kawabata, T; Tsuda, T T; Wada, S

2017-06-12

An Nd:YAG laser-based sodium temperature/wind lidar was developed for the measurement of the northern polar mesosphere and lower thermosphere at Tromsø (69.6N, 19.2E), Norway. Coherent light at 589 nm is produced by sum frequency generation of 1064 nm and 1319 nm from two diode laser end-pumped pulsed Nd:YAG lasers. The output power is as high as 4W, with 4 mJ/pulse at 1000 Hz repetition rate. Five tilting Cassegrain telescopes enable us to make five-direction (zenith, north, south, east, west) observation for temperature and wind simultaneously. This highly stable laser system is first of its kind to operate virtually maintenance-free during the observation season (from late September to March) since 2010.

An Improved Instrument for Investigating Planetary Regolith Microstructure

NASA Technical Reports Server (NTRS)

Nelson, R. M.; Hapke, B. W.; Smythe, W. D.; Manatt, K. S.; Eddy, J.

2005-01-01

The Opposition Effect (OE) is the non-linear increase in the intensity of light scattered from a surface as phase angle approaches 0 deg. It is seen in laboratory experiments and in remote sensing observations of planetary surfaces. Understanding the OE is a requirement for fitting photometric models which produce meaningful results about regolith texture. Previously we have reported measurements from the JPL long arm goniometer and we have shown that this instrument enables us to distinguish between two distinct processes which create the opposition surges, Shadow Hiding (SHOE) and Coherent Backscattering (CBOE). SHOE arises because, as phase angle approaches zero, shadows cast by regolith grains on other grains become invisible to the observer. CBOE results from constructive interference between rays traveling the same path but in opposite directions. Additional information is included in the original extended abstract.

A radio counterpart to a neutron star merger.

PubMed

Hallinan, G; Corsi, A; Mooley, K P; Hotokezaka, K; Nakar, E; Kasliwal, M M; Kaplan, D L; Frail, D A; Myers, S T; Murphy, T; De, K; Dobie, D; Allison, J R; Bannister, K W; Bhalerao, V; Chandra, P; Clarke, T E; Giacintucci, S; Ho, A Y Q; Horesh, A; Kassim, N E; Kulkarni, S R; Lenc, E; Lockman, F J; Lynch, C; Nichols, D; Nissanke, S; Palliyaguru, N; Peters, W M; Piran, T; Rana, J; Sadler, E M; Singer, L P

2017-12-22

Gravitational waves have been detected from a binary neutron star merger event, GW170817. The detection of electromagnetic radiation from the same source has shown that the merger occurred in the outskirts of the galaxy NGC 4993, at a distance of 40 megaparsecs from Earth. We report the detection of a counterpart radio source that appears 16 days after the event, allowing us to diagnose the energetics and environment of the merger. The observed radio emission can be explained by either a collimated ultrarelativistic jet, viewed off-axis, or a cocoon of mildly relativistic ejecta. Within 100 days of the merger, the radio light curves will enable observers to distinguish between these models, and the angular velocity and geometry of the debris will be directly measurable by very long baseline interferometry. Copyright © 2017, American Association for the Advancement of Science.

A frequency standard via spectrum analysis and direct digital synthesis

NASA Astrophysics Data System (ADS)

Li, Dawei; Shi, Daiting; Hu, Ermeng; Wang, Yigen; Tian, Lu; Zhao, Jianye; Wang, Zhong

2014-11-01

We demonstrated a frequency standard based on a detuned coherent population beating phenomenon. In this phenomenon, the beat frequency of the radio frequency for laser modulation and the hyperfine splitting can be obtained by digital signal processing technology. After analyzing the spectrum of the beat frequency, the fluctuation information is obtained and applied to compensate for the frequency shift to generate the standard frequency by the digital synthesis method. Frequency instability of 2.6 × 1012 at 1000 s is observed in our preliminary experiment. By eliminating the phase-locking loop, the method will enable us to achieve a full-digital frequency standard with remarkable stability.

Interfacial Structure and Chemistry of GaN on Ge(111)

NASA Astrophysics Data System (ADS)

Zhang, Siyuan; Zhang, Yucheng; Cui, Ying; Freysoldt, Christoph; Neugebauer, Jörg; Lieten, Ruben R.; Barnard, Jonathan S.; Humphreys, Colin J.

2013-12-01

The interface of GaN grown on Ge(111) by plasma-assisted molecular beam epitaxy is resolved by aberration corrected scanning transmission electron microscopy. A novel interfacial structure with a 5∶4 closely spaced atomic bilayer is observed that explains why the interface is flat, crystalline, and free of GeNx. Density functional theory based total energy calculations show that the interface bilayer contains Ge and Ga atoms, with no N atoms. The 5∶4 bilayer at the interface has a lower energy than a direct stacking of GaN on Ge(111) and enables the 5∶4 lattice-matching growth of GaN.

Medium-energy particle experiments—electron analyzer (MEP-e) for the exploration of energization and radiation in geospace (ERG) mission

NASA Astrophysics Data System (ADS)

Kasahara, Satoshi; Yokota, Shoichiro; Mitani, Takefumi; Asamura, Kazushi; Hirahara, Masafumi; Shibano, Yasuko; Takashima, Takeshi

2018-05-01

The medium-energy particle experiments—electron analyzer onboard the exploration of energization and radiation in geospace spacecraft measures the energy and direction of each incoming electron in the energy range of 7-87 keV. The sensor covers a 2 π-radian disklike field of view with 16 detectors, and the full solid angle coverage is achieved through the spacecraft's spin motion. The electron energy is independently measured by both an electrostatic analyzer and avalanche photodiodes, enabling significant background reduction. We describe the technical approach, data output, and examples of initial observations.[Figure not available: see fulltext.

Correlated Optical Spectroscopy and Transmission Electron Microscopy of Individual Hollow Nanoparticles and their Dimers

PubMed Central

Yang, Linglu; Yan, Bo; Reinhard, Björn M.

2009-01-01

The optical spectra of individual Ag-Au alloy hollow particles were correlated with the particles’ structures obtained by transmission electron microscopy (TEM). The TEM provided direct experimental access to the dimension of the cavity, thickness of the metal shell, and the interparticle distance of hollow particle dimers with high spatial resolution. The analysis of correlated spectral and structural information enabled the quantification of the influence of the core-shell structure on the resonance energy, plasmon lifetime, and plasmon coupling efficiency. Electron beam exposure during TEM inspection was observed to affect plasmon wavelength and lifetime, making optical inspection prior to structural characterization mandatory. PMID:19768108

Detecting Single-Nucleotides by Tunneling Current Measurements at Sub-MHz Temporal Resolution.

PubMed

Morikawa, Takanori; Yokota, Kazumichi; Tanimoto, Sachie; Tsutsui, Makusu; Taniguchi, Masateru

2017-04-18

Label-free detection of single-nucleotides was performed by fast tunneling current measurements in a polar solvent at 1 MHz sampling rate using SiO₂-protected Au nanoprobes. Short current spikes were observed, suggestive of trapping/detrapping of individual nucleotides between the nanoelectrodes. The fall and rise features of the electrical signatures indicated signal retardation by capacitance effects with a time constant of about 10 microseconds. The high temporal resolution revealed current fluctuations, reflecting the molecular conformation degrees of freedom in the electrode gap. The method presented in this work may enable direct characterizations of dynamic changes in single-molecule conformations in an electrode gap in liquid.

Antarctic krill under sea ice: elevated abundance in a narrow band just south of ice edge.

PubMed

Brierley, Andrew S; Fernandes, Paul G; Brandon, Mark A; Armstrong, Frederick; Millard, Nicholas W; McPhail, Steven D; Stevenson, Peter; Pebody, Miles; Perrett, James; Squires, Mark; Bone, Douglas G; Griffiths, Gwyn

2002-03-08

We surveyed Antarctic krill (Euphausia superba) under sea ice using the autonomous underwater vehicle Autosub-2. Krill were concentrated within a band under ice between 1 and 13 kilometers south of the ice edge. Within this band, krill densities were fivefold greater than that of open water. The under-ice environment has long been considered an important habitat for krill, but sampling difficulties have previously prevented direct observations under ice over the scale necessary for robust krill density estimation. Autosub-2 enabled us to make continuous high-resolution measurements of krill density under ice reaching 27 kilometers beyond the ice edge.

Evaluating bandgap distributions of carbon nanotubes via scanning electron microscopy imaging of the Schottky barriers.

PubMed

He, Yujun; Zhang, Jin; Li, Dongqi; Wang, Jiangtao; Wu, Qiong; Wei, Yang; Zhang, Lina; Wang, Jiaping; Liu, Peng; Li, Qunqing; Fan, Shoushan; Jiang, Kaili

2013-01-01

We show that the Schottky barrier at the metal-single walled carbon nanotube (SWCNT) contact can be clearly observed in scanning electron microscopy (SEM) images as a bright contrast segment with length up to micrometers due to the space charge distribution in the depletion region. The lengths of the charge depletion increase with the diameters of semiconducting SWCNTs (s-SWCNTs) when connected to one metal electrode, which enables direct and efficient evaluation of the bandgap distributions of s-SWCNTs. Moreover, this approach can also be applied for a wide variety of semiconducting nanomaterials, adding a new function to conventional SEM.

Red, green and blue reflections enabled in an optically tunable self-organized 3D cubic nanostructured thin film.

PubMed

Lin, Tsung-Hsien; Li, Yannian; Wang, Chun-Ta; Jau, Hung-Chang; Chen, Chun-Wei; Li, Cheng-Chung; Bisoyi, Hari Krishna; Bunning, Timothy J; Li, Quan

2013-09-25

A new light-driven chiral molecular switch doped in a stable blue phase (BP) liquid crystal allows wide optical tunability of three-dimensional cubic nanostructures with a selective reflection wavelength that is reversibly tuned through the visible region. Moreover, unprecedented reversible light-directed red, green, and blue reflections of the self-organized three-dimensional cubic nanostructure in a single film are demonstrated for the first time. Additionally, unusual isothermal photo-stimulated less ordered BP II to more ordered BP I phase transition was observed in the system. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light sensitive memristor with bi-directional and wavelength-dependent conductance control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maier, P.; Hartmann, F., E-mail: fabian.hartmann@physik.uni-wuerzburg.de; Emmerling, M.

2016-07-11

We report the optical control of localized charge on positioned quantum dots in an electro-photo-sensitive memristor. Interband absorption processes in the quantum dot barrier matrix lead to photo-generated electron-hole-pairs that, depending on the applied bias voltage, charge or discharge the quantum dots and hence decrease or increase the conductance. Wavelength-dependent conductance control is observed by illumination with red and infrared light, which leads to charging via interband and discharging via intraband absorption. The presented memristor enables optical conductance control and may thus be considered for sensory applications in artificial neural networks as light-sensitive synapses or optically tunable memories.

Using Movies to Analyse Gene Circuit Dynamics in Single Cells

PubMed Central

Locke, James CW; Elowitz, Michael B

2010-01-01

Preface Many bacterial systems rely on dynamic genetic circuits to control critical processes. A major goal of systems biology is to understand these behaviours in terms of individual genes and their interactions. However, traditional techniques based on population averages wash out critical dynamics that are either unsynchronized between cells or driven by fluctuations, or ‘noise,’ in cellular components. Recently, the combination of time-lapse microscopy, quantitative image analysis, and fluorescent protein reporters has enabled direct observation of multiple cellular components over time in individual cells. In conjunction with mathematical modelling, these techniques are now providing powerful insights into genetic circuit behaviour in diverse microbial systems. PMID:19369953

Re-use of standard ontologies in a water quality vocabulary (Invited)

NASA Astrophysics Data System (ADS)

Cox, S. J.; Simons, B.; Yu, J.

2013-12-01

Observations provide the key constraints on environmental and earth science investigations. Where an investigation uses data sourced from multiple providers, data fusion depends on the observation classifications being comparable. Standard models for observation metadata are available (ISO 19156) which provide slots for key classifiers, in particular, the observed property and observation procedure. While universal use of common vocabularies might be desirable in achieving interoperability, this is unlikely in practice. However, semantic web vocabularies provide the means for asserting proximity and other relationships between items in different vocabularies, thus enabling mediation as an interoperability solution. Here we report on the development of a vocabulary for water quality observations in which recording relationships with existing vocabularies was a core strategy. The vocabulary is required to enable combination of a number of groundwater, surface water and marine water quality datasets on an ongoing basis. Our vocabulary model is based on the principle that observations generally report values of specific parameters which are defined by combining a number of facets. We start from Quantities, Units, Dimensions and Data Types (QUDT), which is an OWL ontology developed by NASA and TopQuadrant. We extend this with two additional classes, for Observed Property and Identified Object, and two linking properties, which enable us to create an observed property vocabulary for water quality applications. This ontology is comparable with models for observed properties developed as part of OGC's Observations and Measurements v1.0 standard, the INSPIRE Generic Conceptual Model, and may also be compared with the W3C SSN Ontology, which is based on the DOLCE Ultralite upper-ontology. Water quality observations commonly report concentrations of chemicals, both natural and contaminant, so we tie many of the Identified Objects to items from Chemical Entities of Biological Interest (ChEBI). ChEBI is an OWL-based dictionary of over 70 000 molecular entities, based on existing scientific work and linked through to International Union of Pure and Applied Chemistry (IUPAC) Nomenclature. Within the model the relevant classes, including those from QUDT, are declared to be subclasses of SKOS Concept, so the resulting vocabularies may be directly mapped to other SKOS-based vocabularies, such as from the NERC Vocabulary Service or the Marine Metadata Initiative, using SKOS predicates. Where the external vocabularies are not published with persistent URIs, such as CUAHSI, the mapping may be recorded more informally using annotations, or use proxy URIs for the external vocabulary. The resulting SKOS vocabularies demonstrate a separation of governance of key definitions such as units and quantities and chemical entities, ensuring reuse where possible and extending and adding detail where necessary.

High-spatial-resolution mapping of catalytic reactions on single particles

DOE PAGES

Wu, Chung-Yeh; Wolf, William J.; Levartovsky, Yehonatan; ...

2017-01-26

We report the critical role in surface reactions and heterogeneous catalysis of metal atoms with low coordination numbers, such as found at atomic steps and surface defects, is firmly established. But despite the growing availability of tools that enable detailed in situ characterization, so far it has not been possible to document this role directly. Surface properties can be mapped with high spatial resolution, and catalytic conversion can be tracked with a clear chemical signature; however, the combination of the two, which would enable high-spatial-resolution detection of reactions on catalytic surfaces, has rarely been achieved. Single-molecule fluorescence spectroscopy has beenmore » used to image and characterize single turnover sites at catalytic surfaces, but is restricted to reactions that generate highly fluorescing product molecules. Herein the chemical conversion of N-heterocyclic carbene molecules attached to catalytic particles is mapped using synchrotron-radiation-based infrared nanospectroscopy with a spatial resolution of 25 nanometres, which enabled particle regions that differ in reactivity to be distinguished. Lastly, these observations demonstrate that, compared to the flat regions on top of the particles, the peripheries of the particles-which contain metal atoms with low coordination numbers-are more active in catalysing oxidation and reduction of chemically active groups in surface-anchored N-heterocyclic carbene molecules.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Chung-Yeh; Wolf, William J.; Levartovsky, Yehonatan

We report the critical role in surface reactions and heterogeneous catalysis of metal atoms with low coordination numbers, such as found at atomic steps and surface defects, is firmly established. But despite the growing availability of tools that enable detailed in situ characterization, so far it has not been possible to document this role directly. Surface properties can be mapped with high spatial resolution, and catalytic conversion can be tracked with a clear chemical signature; however, the combination of the two, which would enable high-spatial-resolution detection of reactions on catalytic surfaces, has rarely been achieved. Single-molecule fluorescence spectroscopy has beenmore » used to image and characterize single turnover sites at catalytic surfaces, but is restricted to reactions that generate highly fluorescing product molecules. Herein the chemical conversion of N-heterocyclic carbene molecules attached to catalytic particles is mapped using synchrotron-radiation-based infrared nanospectroscopy with a spatial resolution of 25 nanometres, which enabled particle regions that differ in reactivity to be distinguished. Lastly, these observations demonstrate that, compared to the flat regions on top of the particles, the peripheries of the particles-which contain metal atoms with low coordination numbers-are more active in catalysing oxidation and reduction of chemically active groups in surface-anchored N-heterocyclic carbene molecules.« less

Characterization of graded TiC layers deposited by HiPIMS method

NASA Astrophysics Data System (ADS)

Bohovicova, Jana; Bonova, Lucia; Halanda, Juraj; Ivan, Jozef; Mesko, Marcel; Advanced Technologies Research Institute Team; Institute of Electronic; Photonic Team

2016-09-01

An advanced yet recent development of sputter technique is high power impulse magnetron sputtering (HiPIMS), in which short, energetic pulses are applied to the target, leading to a formation of an ultra-dense plasma in front of the cathode, that provide a high degree of ionization of sputtered material, and consequently enable to control the energy and the direction of the deposition flux. This gives a possibility to alter composition and microstructure in a controlled manner, enables the optimization of TiC for tribological applications. The aim of this work is to link physical phenomena in transient HiPIMS discharges to microstructural and compositional properties of graded TiC thin films. It was found that Ti bottom layer is contamination free. Compared to the direct current magnetron sputtering films, we observed an element specific reduction of impurities measured by ERDA by a factor 3 for N, 4 for H and by a factor of 20 for O. The high purity of Ti layer is partly explained by gas rarefaction and the cleaning effect of the bombarding ions. Graphitization degree of carbon top layer was elucidated by Raman spectroscopy. The compositional effects are correlated with differences in the film microstructure revealed by SEM, XRD and TEM analysis. This work was supported by VEGA, Project No. 1/0503/15 and APVV, Project No. 15-0168.

Terahertz Emission from Hybrid Perovskites Driven by Ultrafast Charge Separation and Strong Electron-Phonon Coupling.

PubMed

Guzelturk, Burak; Belisle, Rebecca A; Smith, Matthew D; Bruening, Karsten; Prasanna, Rohit; Yuan, Yakun; Gopalan, Venkatraman; Tassone, Christopher J; Karunadasa, Hemamala I; McGehee, Michael D; Lindenberg, Aaron M

2018-03-01

Unusual photophysical properties of organic-inorganic hybrid perovskites have not only enabled exceptional performance in optoelectronic devices, but also led to debates on the nature of charge carriers in these materials. This study makes the first observation of intense terahertz (THz) emission from the hybrid perovskite methylammonium lead iodide (CH 3 NH 3 PbI 3 ) following photoexcitation, enabling an ultrafast probe of charge separation, hot-carrier transport, and carrier-lattice coupling under 1-sun-equivalent illumination conditions. Using this approach, the initial charge separation/transport in the hybrid perovskites is shown to be driven by diffusion and not by surface fields or intrinsic ferroelectricity. Diffusivities of the hot and band-edge carriers along the surface normal direction are calculated by analyzing the emitted THz transients, with direct implications for hot-carrier device applications. Furthermore, photogenerated carriers are found to drive coherent terahertz-frequency lattice distortions, associated with reorganizations of the lead-iodide octahedra as well as coupled vibrations of the organic and inorganic sublattices. This strong and coherent carrier-lattice coupling is resolved on femtosecond timescales and found to be important both for resonant and far-above-gap photoexcitation. This study indicates that ultrafast lattice distortions play a key role in the initial processes associated with charge transport. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Terahertz Emission from Hybrid Perovskites Driven by Ultrafast Charge Separation and Strong Electron-Phonon Coupling

DOE PAGES

Guzelturk, Burak; Belisle, Rebecca A.; Smith, Matthew D.; ...

2018-01-23

Unusual photophysical properties of organic–inorganic hybrid perovskites have not only enabled exceptional performance in optoelectronic devices, but also led to debates on the nature of charge carriers in these materials. This study makes the first observation of intense terahertz (THz) emission from the hybrid perovskite methylammonium lead iodide (CH 3NH 3PbI 3) following photoexcitation, enabling an ultrafast probe of charge separation, hot–carrier transport, and carrier–lattice coupling under 1–sun–equivalent illumination conditions. Using this approach, the initial charge separation/transport in the hybrid perovskites is shown to be driven by diffusion and not by surface fields or intrinsic ferroelectricity. Diffusivities of the hotmore » and band–edge carriers along the surface normal direction are calculated by analyzing the emitted THz transients, with direct implications for hot–carrier device applications. Furthermore, photogenerated carriers are found to drive coherent terahertz–frequency lattice distortions, associated with reorganizations of the lead–iodide octahedra as well as coupled vibrations of the organic and inorganic sublattices. This strong and coherent carrier–lattice coupling is resolved on femtosecond timescales and found to be important both for resonant and far–above–gap photoexcitation. As a result, this study indicates that ultrafast lattice distortions play a key role in the initial processes associated with charge transport.« less

Protocol for the administration of haemofiltration fluids and using patient group electrolytes direction.

PubMed

Kingston, Diana; Sykes, Siobhan; Raper, Sarah

2002-01-01

A patient group direction (PGD) is a specific written instruction for the supply or administration of named medicines in an identified clinical situation The introduction of a PGD must demonstrate a benefit for patients Haemofiltration is widely accepted as the treatment of choice when caring for critically ill patients in acute renal failure on an intensive care unit The haemofiltration PGD improves patient care by providing standardisation in administration of fluids and electrolytes and enabling nurses to respond rapidly to changes in biochemistry during haemofiltration This paper describes the development and implementation of a protocol to enable nurses to administer haemofiltration fluids and electrolytes under a patient group direction.

Acting Administrator Lightfoot Comments on New Presidential Space Policy, Return to Moon

NASA Image and Video Library

2017-12-11

Acting NASA Administrator Robert Lightfoot comments on Space Policy Directive-1, signed by President Trump at the White House on Monday, Dec. 11.  It directs NASA’s human spaceflight program back to the Moon, as recommended by the National Space Council.    The directive calls for NASA to lead an innovative and sustainable program of exploration with commercial and international partners to enable human expansion across the solar system, and to bring back to Earth new knowledge and opportunities for human advancement. This effort will more effectively organize government, private industry, and international efforts toward returning humans on the Moon, and will lay the foundation that will eventually enable human exploration of Mars.

Modelling directional solidification

NASA Technical Reports Server (NTRS)

Wilcox, William R.

1991-01-01

The long range goal of this program is to develop an improved understanding of phenomena of importance to directional solidification and to enable explanation and prediction of differences in behavior between solidification on Earth and in space. Current emphasis is on determining the influence of perturbations on directional solidification.

Time motion study using mixed methods to assess service delivery by frontline health workers from South India: methods.

PubMed

Singh, Samiksha; Upadhyaya, Sanjeev; Deshmukh, Pradeep; Dongre, Amol; Dwivedi, Neha; Dey, Deepak; Kumar, Vijay

2018-04-02

In India, amidst the increasing number of health programmes, there are concerns about the performance of frontline health workers (FLHW). We assessed the time utilisation and factors affecting the work of frontline health workers from South India. This is a mixed methods study using time and motion (TAM) direct observations and qualitative enquiry among frontline/community health workers. These included 43 female and 6 male multipurpose health workers (namely, auxiliary nurse midwives (ANMs) and male-MPHWs), 12 nutrition and health workers (Anganwadi workers, AWWs) and 53 incentive-based community health workers (accredited social health activists, ASHAs). We conducted the study in two phases. In the formative phase, we conducted an in-depth inductive investigation to develop observation checklists and qualitative tools. The main study involved deductive approach for TAM observations. This enabled us to observe a larger sample to capture variations across non-tribal and tribal regions and different health cadres. For the main study, we developed GPRS-enabled android-based application to precisely record time, multi-tasking and field movement. We conducted non-participatory direct observations (home to home) for consecutively 6 days for each participant. We conducted in-depth interviews with all the participants and 33 of their supervisors and relevant officials. We conducted six focus group discussions (FGDs) with ASHAs and one FGD with ANMs to validate preliminary findings. We established a mechanism for quality assurance of data collection and analysis. We analysed the data separately for each cadre and stratified for non-tribal and tribal regions. On any working day, the ANMs spent median 7:04 h, male-MPHWs spent median 5:44 h and AWWs spent median 6:50 h on the job. The time spent on the job was less among the FLHWs from tribal areas as compared to those from non-tribal areas. ANMs and AWWs prioritised maternal and child health, while male-MPHWs were involved in seasonal diseases and school health. ASHAs visited homes to provide maternal health, basic curative care, and follow-up of tuberculosis patients. The results describe issues related with work planning, time management and several systemic, community-based and personnel factors affecting work of FLHWs. TAM study with mixed methods can help researchers as well as managers to periodically review work patterns, devise appropriate job responsibilities and improve the efficiency of health workers.

Examination of the perceived agility and balance during a reactive agility task.

PubMed

Stirling, Leia; Eke, Chika; Cain, Stephen M

2018-01-01

In vehicle dynamics, it is commonly understood that there is an inverse relationship between stability and maneuverability. However, animal studies have found that stability and maneuverability can coincide. In this study, we examine humans running a reactive agility obstacle and consider the relationship between observational perceived agility and balance, as well as the relationship between quantified surrogates of agility and balance. Recreational athletes (n = 18) completed the agility task while wearing inertial measurement units (IMUs) on their body. The task was also video-recorded. An observational study was completed by a separate group of adults (n = 33) that were asked to view the videos and score each athlete on a Likert scale for balance and for agility. The data from the body-worn IMUs were used to estimate quantified surrogate measures for agility and balance, and to assess if the relationship between the quantified agility and balance was in the same direction as the perceived relationship from the Likert scale responses. Results indicate that athletes that were given a higher Likert agility score were also given a higher balance score (rs = 0.75,p < 0.001). Quantitative surrogates of agility and balance also showed this same relationship. Additional insights on technique for this reactive agility task were informed by the quantitative surrogates. We observed the importance of stepping technique in achieving the faster completion times. The fast performing athletes spent a greater proportion of the task in double support and lower overall time in single support indicating increased periods of static stability. The fast performing athletes did not have a higher body speed, but performed the task with a more efficient technique, using foot placement to enable heading changes, and thus may have had a more efficient path. Similar to animal studies, people use technique to enable agile strategies while also enabling increased balance across the task.

OceanVideoLab: A Tool for Exploring Underwater Video

NASA Astrophysics Data System (ADS)

Ferrini, V. L.; Morton, J. J.; Wiener, C.

2016-02-01

Video imagery acquired with underwater vehicles is an essential tool for characterizing seafloor ecosystems and seafloor geology. It is a fundamental component of ocean exploration that facilitates real-time operations, augments multidisciplinary scientific research, and holds tremendous potential for public outreach and engagement. Acquiring, documenting, managing, preserving and providing access to large volumes of video acquired with underwater vehicles presents a variety of data stewardship challenges to the oceanographic community. As a result, only a fraction of underwater video content collected with research submersibles is documented, discoverable and/or viewable online. With more than 1 billion users, YouTube offers infrastructure that can be leveraged to help address some of the challenges associated with sharing underwater video with a broad global audience. Anyone can post content to YouTube, and some oceanographic organizations, such as the Schmidt Ocean Institute, have begun live-streaming video directly from underwater vehicles. OceanVideoLab (oceanvideolab.org) was developed to help improve access to underwater video through simple annotation, browse functionality, and integration with related environmental data. Any underwater video that is publicly accessible on YouTube can be registered with OceanVideoLab by simply providing a URL. It is strongly recommended that a navigational file also be supplied to enable geo-referencing of observations. Once a video is registered, it can be viewed and annotated using a simple user interface that integrates observations with vehicle navigation data if provided. This interface includes an interactive map and a list of previous annotations that allows users to jump to times of specific observations in the video. Future enhancements to OceanVideoLab will include the deployment of a search interface, the development of an application program interface (API) that will drive the search and enable querying of content by other systems/tools, the integration of related environmental data from complementary data systems (e.g. temperature, bathymetry), and the expansion of infrastructure to enable broad crowdsourcing of annotations.

Direct detection of a break in the teraelectronvolt cosmic-ray spectrum of electrons and positrons

NASA Astrophysics Data System (ADS)

DAMPE Collaboration; Ambrosi, G.; An, Q.; Asfandiyarov, R.; Azzarello, P.; Bernardini, P.; Bertucci, B.; Cai, M. S.; Chang, J.; Chen, D. Y.; Chen, H. F.; Chen, J. L.; Chen, W.; Cui, M. Y.; Cui, T. S.; D'Amone, A.; de Benedittis, A.; De Mitri, I.; di Santo, M.; Dong, J. N.; Dong, T. K.; Dong, Y. F.; Dong, Z. X.; Donvito, G.; Droz, D.; Duan, K. K.; Duan, J. L.; Duranti, M.; D'Urso, D.; Fan, R. R.; Fan, Y. Z.; Fang, F.; Feng, C. Q.; Feng, L.; Fusco, P.; Gallo, V.; Gan, F. J.; Gao, M.; Gao, S. S.; Gargano, F.; Garrappa, S.; Gong, K.; Gong, Y. Z.; Guo, D. Y.; Guo, J. H.; Hu, Y. M.; Huang, G. S.; Huang, Y. Y.; Ionica, M.; Jiang, D.; Jiang, W.; Jin, X.; Kong, J.; Lei, S. J.; Li, S.; Li, X.; Li, W. L.; Li, Y.; Liang, Y. F.; Liang, Y. M.; Liao, N. H.; Liu, H.; Liu, J.; Liu, S. B.; Liu, W. Q.; Liu, Y.; Loparco, F.; Ma, M.; Ma, P. X.; Ma, S. Y.; Ma, T.; Ma, X. Q.; Ma, X. Y.; Marsella, G.; Mazziotta, M. N.; Mo, D.; Niu, X. Y.; Peng, X. Y.; Peng, W. X.; Qiao, R.; Rao, J. N.; Salinas, M. M.; Shang, G. Z.; H. Shen, W.; Shen, Z. Q.; Shen, Z. T.; Song, J. X.; Su, H.; Su, M.; Sun, Z. Y.; Surdo, A.; Teng, X. J.; Tian, X. B.; Tykhonov, A.; Vagelli, V.; Vitillo, S.; Wang, C.; Wang, H.; Wang, H. Y.; Wang, J. Z.; Wang, L. G.; Wang, Q.; Wang, S.; Wang, X. H.; Wang, X. L.; Wang, Y. F.; Wang, Y. P.; Wang, Y. Z.; Wen, S. C.; Wang, Z. M.; Wei, D. M.; Wei, J. J.; Wei, Y. F.; Wu, D.; Wu, J.; Wu, L. B.; Wu, S. S.; Wu, X.; Xi, K.; Xia, Z. Q.; Xin, Y. L.; Xu, H. T.; Xu, Z. L.; Xu, Z. Z.; Xue, G. F.; Yang, H. B.; Yang, P.; Yang, Y. Q.; Yang, Z. L.; Yao, H. J.; Yu, Y. H.; Yuan, Q.; Yue, C.; Zang, J. J.; Zhang, C.; Zhang, D. L.; Zhang, F.; Zhang, J. B.; Zhang, J. Y.; Zhang, J. Z.; Zhang, L.; Zhang, P. F.; Zhang, S. X.; Zhang, W. Z.; Zhang, Y.; Zhang, Y. J.; Zhang, Y. Q.; Zhang, Y. L.; Zhang, Y. P.; Zhang, Z.; Zhang, Z. Y.; Zhao, H.; Zhao, H. Y.; Zhao, X. F.; Zhou, C. Y.; Zhou, Y.; Zhu, X.; Zhu, Y.; Zimmer, S.

2017-12-01

High-energy cosmic-ray electrons and positrons (CREs), which lose energy quickly during their propagation, provide a probe of Galactic high-energy processes and may enable the observation of phenomena such as dark-matter particle annihilation or decay. The CRE spectrum has been measured directly up to approximately 2 teraelectronvolts in previous balloon- or space-borne experiments, and indirectly up to approximately 5 teraelectronvolts using ground-based Cherenkov γ-ray telescope arrays. Evidence for a spectral break in the teraelectronvolt energy range has been provided by indirect measurements, although the results were qualified by sizeable systematic uncertainties. Here we report a direct measurement of CREs in the energy range 25 gigaelectronvolts to 4.6 teraelectronvolts by the Dark Matter Particle Explorer (DAMPE) with unprecedentedly high energy resolution and low background. The largest part of the spectrum can be well fitted by a ‘smoothly broken power-law’ model rather than a single power-law model. The direct detection of a spectral break at about 0.9 teraelectronvolts confirms the evidence found by previous indirect measurements, clarifies the behaviour of the CRE spectrum at energies above 1 teraelectronvolt and sheds light on the physical origin of the sub-teraelectronvolt CREs.

Towards real-time flood forecasting in hydraulics: merits of in situ discharge and water level data assimilation for the modeling of the Marne catchment in France

NASA Astrophysics Data System (ADS)

Ricci, S. M.; Habert, J.; Le Pape, E.; Piacentini, A.; Jonville, G.; Thual, O.; Zaoui, F.

2011-12-01

The present study describes the assimilation of river flow and water level observations and the resulting improvement in flood forecasting. The Kalman Filter algorithm was built on top of the one-dimensional hydraulic model, MASCARET, [1] which describes the Saint-Venant equations. The assimilation algorithm folds in two steps: the first one was based on the assumption that the upstream flow can be adjusted using a three-parameter correction; the second one consisted of directly correcting the hydraulic state. This procedure was previously applied on the Adour Maritime Catchment using water level observations [2]. On average, it was shown that the data assimilation procedure enables an improvement of 80% in the simulated water level over the reanalysis period, 60 % in the forecast water level at a one-hour lead time, and 25% at a twelve-hour lead time. The procedure was then applied on the Marne Catchment, which includes karstic tributaries, located East of the Paris basin, characterized by long flooding periods and strong sensitivity to local precipitations. The objective was to geographically extend and improve the existing model used by the flood forecasting service located in Chalons-en-Champagne. A hydrological study first enabled the specification of boundary conditions (upstream flow or lateral inflow), then the hydraulic model was calibrated using in situ discharge data (adjustment of Strickler coefficients or cross sectional geometry). The assimilation of water level data enabled the reduction of the uncertainty in the hydrological boundary conditions and led to significant improvement of the simulated water level in re-analysis and forecast modes. Still, because of errors in the Strickler coefficients or cross section geometry, the improvement of the simulated water level sometimes resulted in a degradation of discharge values. This problem was overcome by controlling the correction of the hydrological boundary conditions by directly assimilating discharge observations rather than water level observations. As this approach leads to a satisfying simulation of flood events in the Marne catchment in re-analysis and forecast mode, ongoing work aims at controlling Strickler coefficients through data assimilation procedures in order to simultaneously improve the water level and discharge state. [1] N. Goutal, F. Maurel: A finite volume solver for 1D shallow water equations applied to an actual river, Int. J. Numer. Meth. Fluids, 38(2), 1--19, 2002. [2] S. Ricci, A. Piacentini, O. Thual, E. Le Pape, G. Jonville, 2011: Correction of upstream flow and hydraulic state with data assimilation on the context of flood forecasting. Submitted to Hydrol. Earth Syst. Sci, In review.

Enable: Developing Instructional Language Skills.

ERIC Educational Resources Information Center

Witt, Beth

The program presented in this manual provides a structure and activities for systematic development of effective listening comprehension in typical and atypical children. The complete ENABLE kit comes with pictures, cut-outs, and puppets to illustrate the directives, questions, and narrative activities. The manual includes an organizational and…

Spectral structure and stability studies on microstructure-fiber continuum

NASA Astrophysics Data System (ADS)

Gu, Xun; Kimmel, Mark; Zeek, Erik; Shreenath, Aparna P.; Trebino, Rick P.; Windeler, Robert S.

2003-07-01

Although previous direct measurements of the microstructure-fiber continuum have all showed a smooth and stable spectrum, our cross-correlation frequency-resolved optical gating (XFROG) full-intensity-and-phase characterization of the continuum pulse, utilizing sum-frequency-generation with a pre-characterized reference pulse and the angle-dithered-crystal technique, indicates that fine-scale spectral structure exists on a single-shot basis, contrary to previous observations. In particular, deep and fine oscillations are found in the retrieved spectrum, and the retrieved trace contains a "measles" pattern, whereas the measured trace and the independently-measured spectrum are rather smooth. The discrepancy is shown to be the result of unstable single-shot spectral structure. Although the XFROG measurement is not able to directly measure the single-shot fine structure in the trace, the redundancy of information in FROG traces enables the retrieval algorithm to correctly recognize the existence of the spectral fine structure, and restore the structure in the retrieved trace and spectrum. Numerical simulations have supported our hypothesis, and we directly observed the fine spectral structure in single-shot measurements of the continuum spectrum and the structure was seen to be highly unstable, the continuum spectrum appearing smooth only when many shots are averaged. Despite the structure and instability in the continuum spectrum, coherence experiments also reveal that the spectral phase is rather stable, being able to produce well-defined spectral fringes across the entire continuum bandwidth.

Eclipse-induced wind changes over the British Isles on the 20 March 2015

PubMed Central

2016-01-01

The British Isles benefits from dense meteorological observation networks, enabling insights into the still-unresolved effects of solar eclipse events on the near-surface wind field. The near-surface effects of the solar eclipse of 20 March 2015 are derived through comparison of output from the Met Office’s operational weather forecast model (which is ignorant of the eclipse) with data from two meteorological networks: the Met Office’s land surface station (MIDAS) network and a roadside measurement network operated by Vaisala. Synoptic-evolution relative calculations reveal the cooling and increase in relative humidity almost universally attributed to eclipse events. In addition, a slackening of wind speeds by up to about 2 knots in already weak winds and backing in wind direction of about 20° under clear skies across middle England are attributed to the eclipse event. The slackening of wind speed is consistent with the previously reported boundary layer stabilization during eclipse events. Wind direction changes have previously been attributed to a large-scale ‘eclipse-induced cold-cored cyclone’, mountain slope flows, and changes in the strength of sea breezes. A new explanation is proposed here by analogy with nocturnal wind changes at sunset and shown to predict direction changes consistent with those observed. This article is part of the themed issue ‘Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse’. PMID:27550759

Modelling Directional Solidification

NASA Technical Reports Server (NTRS)

Wilcox, William R.; Regel, Liya L.; Zhou, Jian; Yuan, Weijun

1992-01-01

The long range goal of this program has been to develop an improved understanding of phenomena of importance to directional solidification, in order to enable explanation and prediction of differences in behavior between solidification on Earth and in space. Current emphasis is on determining the influence of perturbations on directional solidification.

Observation of b 2 symmetry vibrational levels of the SO 2C 1B 2 state: Vibrational level staggering, Coriolis interactions, and rotation-vibration constants

DOE PAGES

Park, G. Barratt; Jiang, Jun; Saladrigas, Catherine A.; ...

2016-04-14

Here, the C 1B 2 state of SO 2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b 2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X ~ state are vibronically forbidden. We use IR-UV double resonance to observe the b 2 vibrational levels of the C state below 1600 cm –1 of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results frommore » the double-minimum potential. In addition, it allows us to deperturb the strong c-axis Coriolis interactions between levels of a 1 and b 2 vibrational symmetry, and to determine accurately the vibrational dependence of the rotational constants in the distorted C electronic state.« less

Observation of b 2 symmetry vibrational levels of the SO 2C 1B 2 state: Vibrational level staggering, Coriolis interactions, and rotation-vibration constants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, G. Barratt; Jiang, Jun; Saladrigas, Catherine A.

Here, the C 1B 2 state of SO 2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b 2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X ~ state are vibronically forbidden. We use IR-UV double resonance to observe the b 2 vibrational levels of the C state below 1600 cm –1 of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results frommore » the double-minimum potential. In addition, it allows us to deperturb the strong c-axis Coriolis interactions between levels of a 1 and b 2 vibrational symmetry, and to determine accurately the vibrational dependence of the rotational constants in the distorted C electronic state.« less

Observation of finite-wavelength screening in high-energy-density matter

DOE PAGES

Chapman, D. A.; Vorberger, J.; Fletcher, L. B.; ...

2015-04-23

A key component for the description of charged particle systems is the screening of the Coulomb interaction between charge carriers. First investigated in the 1920s by Debye and Hückel for electrolytes, charge screening is important for determining the structural and transport properties of matter as diverse as astrophysical and laboratory plasmas, nuclear matter such as quark-gluon plasmas, electrons in solids, planetary cores and charged macromolecules. For systems with negligible dynamics, screening is still mostly described using a Debye–Hückel-type approach. Here, we report the novel observation of a significant departure from the Debye–Hückel-type model in high-energy-density matter by probing laser-driven, shock-compressedmore » plastic with high-energy X-rays. We use spectrally resolved X-ray scattering in a geometry that enables direct investigation of the screening cloud, and demonstrate that the observed elastic scattering amplitude is only well described within a more general approach.« less

Mentalizing skills do not differentiate believers from non-believers, but credibility enhancing displays do.

PubMed

Maij, David L R; van Harreveld, Frenk; Gervais, Will; Schrag, Yann; Mohr, Christine; van Elk, Michiel

2017-01-01

The ability to mentalize has been marked as an important cognitive mechanism enabling belief in supernatural agents. In five studies we cross-culturally investigated the relationship between mentalizing and belief in supernatural agents with large sample sizes (over 67,000 participants in total) and different operationalizations of mentalizing. The relative importance of mentalizing for endorsing supernatural beliefs was directly compared with credibility enhancing displays-the extent to which people observed credible religious acts during their upbringing. We also compared autistic with neurotypical adolescents. The empathy quotient and the autism-spectrum quotient were not predictive of belief in supernatural agents in all countries (i.e., The Netherlands, Switzerland and the United States), although we did observe a curvilinear effect in the United States. We further observed a strong influence of credibility enhancing displays on belief in supernatural agents. These findings highlight the importance of cultural learning for acquiring supernatural beliefs and ask for reconsiderations of the importance of mentalizing.

Mentalizing skills do not differentiate believers from non-believers, but credibility enhancing displays do

PubMed Central

van Harreveld, Frenk; Gervais, Will; Schrag, Yann; Mohr, Christine; van Elk, Michiel

2017-01-01

The ability to mentalize has been marked as an important cognitive mechanism enabling belief in supernatural agents. In five studies we cross-culturally investigated the relationship between mentalizing and belief in supernatural agents with large sample sizes (over 67,000 participants in total) and different operationalizations of mentalizing. The relative importance of mentalizing for endorsing supernatural beliefs was directly compared with credibility enhancing displays–the extent to which people observed credible religious acts during their upbringing. We also compared autistic with neurotypical adolescents. The empathy quotient and the autism-spectrum quotient were not predictive of belief in supernatural agents in all countries (i.e., The Netherlands, Switzerland and the United States), although we did observe a curvilinear effect in the United States. We further observed a strong influence of credibility enhancing displays on belief in supernatural agents. These findings highlight the importance of cultural learning for acquiring supernatural beliefs and ask for reconsiderations of the importance of mentalizing. PMID:28832606

Learning About Causes From People: Observational Causal Learning in 24-Month-Old Infants

PubMed Central

Meltzoff, Andrew N.; Waismeyer, Anna; Gopnik, Alison

2013-01-01

How do infants and young children learn about the causal structure of the world around them? In 4 experiments we investigate whether young children initially give special weight to the outcomes of goal-directed interventions they see others perform and use this to distinguish correlations from genuine causal relations—observational causal learning. In a new 2-choice procedure, 2- to 4-year-old children saw 2 identical objects (potential causes). Activation of 1 but not the other triggered a spatially remote effect. Children systematically intervened on the causal object and predictively looked to the effect. Results fell to chance when the cause and effect were temporally reversed, so that the events were merely associated but not causally related. The youngest children (24- to 36-month-olds) were more likely to make causal inferences when covariations were the outcome of human interventions than when they were not. Observational causal learning may be a fundamental learning mechanism that enables infants to abstract the causal structure of the world. PMID:22369335

Land-Breeze Forecasting

NASA Technical Reports Server (NTRS)

Case, Jonathan L.; Wheeler, Mark M.; Merceret, Francis J. (Technical Monitor)

2002-01-01

The nocturnal land breeze at the Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) is both operationally significant and challenging to forecast. The occurrence and timing of land breezes impact low-level winds, atmospheric stability, low temperatures, and fog development. Accurate predictions of the land breeze are critical for toxic material dispersion forecasts associated with space launch missions, since wind direction and low-level stability can change noticeably with the onset of a land breeze. This report presents a seven-year observational study of land breezes over east-central Florida from 1995 to 2001. This comprehensive analysis was enabled by the high-resolution tower observations over KSC/CCAFS. Five-minute observations of winds, temperature, and moisture along with 9 15-MHz Doppler Radar Wind Profiler data were used to analyze specific land-breeze cases, while the tower data were used to construct a composite climatology. Utilities derived from this climatology were developed to assist forecasters in determining the land-breeze occurrence, timing, and movement based on predicted meteorological conditions.

Atomic scale dynamics of a solid state chemical reaction directly determined by annular dark-field electron microscopy.

PubMed

Pennycook, Timothy J; Jones, Lewys; Pettersson, Henrik; Coelho, João; Canavan, Megan; Mendoza-Sanchez, Beatriz; Nicolosi, Valeria; Nellist, Peter D

2014-12-22

Dynamic processes, such as solid-state chemical reactions and phase changes, are ubiquitous in materials science, and developing a capability to observe the mechanisms of such processes on the atomic scale can offer new insights across a wide range of materials systems. Aberration correction in scanning transmission electron microscopy (STEM) has enabled atomic resolution imaging at significantly reduced beam energies and electron doses. It has also made possible the quantitative determination of the composition and occupancy of atomic columns using the atomic number (Z)-contrast annular dark-field (ADF) imaging available in STEM. Here we combine these benefits to record the motions and quantitative changes in the occupancy of individual atomic columns during a solid-state chemical reaction in manganese oxides. These oxides are of great interest for energy-storage applications such as for electrode materials in pseudocapacitors. We employ rapid scanning in STEM to both drive and directly observe the atomic scale dynamics behind the transformation of Mn3O4 into MnO. The results demonstrate we now have the experimental capability to understand the complex atomic mechanisms involved in phase changes and solid state chemical reactions.

Gravitaxis in Spherical Janus Swimming Devices

PubMed Central

2013-01-01

In this work, we show that the asymmetrical distribution of mass at the surface of catalytic Janus swimmers results in the devices preferentially propelling themselves upward in a gravitational field. We demonstrate the existence of this gravitaxis phenomenon by observing the trajectories of fueled Janus swimmers, which generate thrust along a vector pointing away from their metallically coated half. We report that as the size of the spherical swimmer increases, the propulsive trajectories are no longer isotropic with respect to gravity, and they start to show a pronounced tendency to move in an upward direction. We suggest that this effect is due to the platinum caps asymmetric mass exerting an increasing influence on the azimuthal angle of the Janus sphere with size, biasing its orientation toward a configuration where the heavier propulsion generating surface faces down. This argument is supported by the good agreement we find between the experimentally observed azimuthal angle distribution for the Janus swimmers and predictions made by simple Boltzmann statistics. This gravitaxis phenomenon provides a mechanism to autonomously control and direct the motion of catalytic swimming devices and so enable a route to make autonomous transport devices and develop new separation, sensing, and controlled release applications. PMID:24134682

Searching for dark matter-dark energy interactions: Going beyond the conformal case

NASA Astrophysics Data System (ADS)

van de Bruck, Carsten; Mifsud, Jurgen

2018-01-01

We consider several cosmological models which allow for nongravitational direct couplings between dark matter and dark energy. The distinguishing cosmological features of these couplings can be probed by current cosmological observations, thus enabling us to place constraints on these specific interactions which are composed of the conformal and disformal coupling functions. We perform a global analysis in order to independently constrain the conformal, disformal, and mixed interactions between dark matter and dark energy by combining current data from: Planck observations of the cosmic microwave background radiation anisotropies, a combination of measurements of baryon acoustic oscillations, a supernova type Ia sample, a compilation of Hubble parameter measurements estimated from the cosmic chronometers approach, direct measurements of the expansion rate of the Universe today, and a compilation of growth of structure measurements. We find that in these coupled dark-energy models, the influence of the local value of the Hubble constant does not significantly alter the inferred constraints when we consider joint analyses that include all cosmological probes. Moreover, the parameter constraints are remarkably improved with the inclusion of the growth of structure data set measurements. We find no compelling evidence for an interaction within the dark sector of the Universe.

Measurements from an Aerial Vehicle: A New Tool for Planetary Exploration

NASA Technical Reports Server (NTRS)

Wright, Henry S.; Levine, Joel S.; Croom, Mark A.; Edwards, William C.; Qualls, Garry D.; Gasbarre, Joseph F.

2004-01-01

Aerial vehicles fill a unique planetary science measurement gap, that of regional-scale, near-surface observation, while providing a fresh perspective for potential discovery. Aerial vehicles used in planetary exploration bridge the scale and resolution measurement gaps between orbiters (global perspective with limited spatial resolution) and landers (local perspective with high spatial resolution) thus complementing and extending orbital and landed measurements. Planetary aerial vehicles can also survey scientifically interesting terrain that is inaccessible or hazardous to landed missions. The use of aerial assets for performing observations on Mars, Titan, or Venus will enable direct measurements and direct follow-ons to recent discoveries. Aerial vehicles can be used for remote sensing of the interior, surface and atmosphere of Mars, Venus and Titan. Types of aerial vehicles considered are airplane "heavier than air" and airships and balloons "lighter than air". Interdependencies between the science measurements, science goals and objectives, and platform implementation illustrate how the proper balance of science, engineering, and cost, can be achieved to allow for a successful mission. Classification of measurement types along with how those measurements resolve science questions and how these instruments are accommodated within the mission context are discussed.

Many-body effects in valleytronics: direct measurement of valley lifetimes in single-layer MoS2.

PubMed

Mai, Cong; Barrette, Andrew; Yu, Yifei; Semenov, Yuriy G; Kim, Ki Wook; Cao, Linyou; Gundogdu, Kenan

2014-01-08

Single layer MoS2 is an ideal material for the emerging field of "valleytronics" in which charge carrier momentum can be finely controlled by optical excitation. This system is also known to exhibit strong many-body interactions as observed by tightly bound excitons and trions. Here we report direct measurements of valley relaxation dynamics in single layer MoS2, by using ultrafast transient absorption spectroscopy. Our results show that strong Coulomb interactions significantly impact valley population dynamics. Initial excitation by circularly polarized light creates electron-hole pairs within the K-valley. These excitons coherently couple to dark intervalley excitonic states, which facilitate fast electron valley depolarization. Hole valley relaxation is delayed up to about 10 ps due to nondegeneracy of the valence band spin states. Intervalley biexciton formation reveals the hole valley relaxation dynamics. We observe that biexcitons form with more than an order of magnitude larger binding energy compared to conventional semiconductors. These measurements provide significant insight into valley specific processes in 2D semiconductors. Hence they could be used to suggest routes to design semiconducting materials that enable control of valley polarization.

Direct Visualization of Aggregate Morphology and Dynamics in a Model Soil Organic–Mineral System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hufschmid, Ryan; Newcomb, Christina J.; Grate, Jay W.

Interactions between mineral surfaces and organic matter are ubiquitous in soils and the environment. Through both physical and chemical mechanisms, organic-mineral assemblages prevent decomposition of soil organic matter by limiting accessibility or reducing efficacy of enzymes and microbes. To understand the mechanisms underlying organic-mineral interactions, researchers have begun to interrogate these systems at smaller length scales. Current techniques that maintain a hydrated state and allow researchers to characterize nanometer length scales are limited. Here we chose a model organic-mineral system and performed complementary imaging techniques that enable direct nanoscale observations in environmentally relevant conditions: cryogenic TEM and in-situ liquid cellmore » TEM. We observed a three-fold increase in aggregate size of goethite nanoparticles upon addition of a model organic phosphate ligand and quantification of nanoparticle orientation reveals a preference for side-to-side interactions independent of the addition of an organic ligand. Additionally, in-situ liquid cell TEM experiments provides a dynamic view of the interactions allowing us to report velocities of mineral assemblages during aggregation and disaggregation, which could potentially provide binding energetics and kinetic parameters about organic-mineral and mineral-mineral systems.« less

The structure and mechanics of Moso bamboo material

PubMed Central

Dixon, P. G.; Gibson, L. J.

2014-01-01

Although bamboo has been used structurally for millennia, there is currently increasing interest in the development of renewable and sustainable structural bamboo products (SBPs). These SBPs are analogous to wood products such as plywood, oriented strand board and glue-laminated wood. In this study, the properties of natural Moso bamboo (Phyllostachys pubescens) are investigated to further enable the processing and design of SBPs. The radial and longitudinal density gradients in bamboo give rise to variations in the mechanical properties. Here, we measure the flexural properties of Moso bamboo in the axial direction, along with the compressive strengths in the axial and transverse directions. Based on the microstructural variations (observed with scanning electron microscopy) and extrapolated solid cell wall properties of bamboo, we develop models, which describe the experimental results well. Compared to common North American construction woods loaded along the axial direction, Moso bamboo is approximately as stiff and substantially stronger, in both flexure and compression but denser. This work contributes to critical knowledge surrounding the microstructure and mechanical properties of bamboo, which are vital to the engineering and design of sustainable SBPs. PMID:25056211

Vectorial point spread function and optical transfer function in oblique plane imaging.

PubMed

Kim, Jeongmin; Li, Tongcang; Wang, Yuan; Zhang, Xiang

2014-05-05

Oblique plane imaging, using remote focusing with a tilted mirror, enables direct two-dimensional (2D) imaging of any inclined plane of interest in three-dimensional (3D) specimens. It can image real-time dynamics of a living sample that changes rapidly or evolves its structure along arbitrary orientations. It also allows direct observations of any tilted target plane in an object of which orientational information is inaccessible during sample preparation. In this work, we study the optical resolution of this innovative wide-field imaging method. Using the vectorial diffraction theory, we formulate the vectorial point spread function (PSF) of direct oblique plane imaging. The anisotropic lateral resolving power caused by light clipping from the tilted mirror is theoretically analyzed for all oblique angles. We show that the 2D PSF in oblique plane imaging is conceptually different from the inclined 2D slice of the 3D PSF in conventional lateral imaging. Vectorial optical transfer function (OTF) of oblique plane imaging is also calculated by the fast Fourier transform (FFT) method to study effects of oblique angles on frequency responses.

Direct measurements of HOx radicals in the marine boundary layer: testing the current tropospheric chemistry mechanism.

PubMed

Kanaya, Yugo; Akimoto, Hajime

2002-01-01

OH and HO(2) radicals, atmospheric detergents, and the reservoir thereof, play central roles in tropospheric chemistry. In spite of their importance, we had no choice but to trust their concentrations predicted by modeling studies based on known chemical processes. However, recent direct measurements of these radicals have enabled us to test and revise our knowledge of the processes by comparing the predicted and observed values of the radical concentrations. We developed a laser-induced fluorescence (LIF) instrument and successfully observed OH and HO(2) at three remote islands of Japan (Oki Island, Okinawa Island, and Rishiri Island). At Okinawa Island, the observed daytime level of HO(2) agreed closely with the model estimates, suggesting that the photochemistry at Okinawa is well described by the current chemistry mechanism. At Rishiri Island, in contrast, the observed daytime level of HO(2) was consistently much lower than the calculated values. We proposed that iodine chemistry, usually not incorporated into the mechanism, is at least partly responsible for the discrepancy in the results. At night, HO(2) was detected at levels greater than 1 pptv at all three islands, suggesting the presence of processes in the dark that produce radicals. We showed that ozone reactions with unsaturated hydrocarbons, including monoterpenes, could significantly contribute to radical production. Copyright 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2: 199-211, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10019

An in-situ analytical scanning and transmission electron microscopy investigation of structure-property relationships in electronic materials

NASA Astrophysics Data System (ADS)

Wagner, Andrew James

As electronic and mechanical devices are scaled downward in size and upward in complexity, macroscopic principles no longer apply. Synthesis of three-dimensionally confined structures exhibit quantum confinement effects allowing, for example, silicon nanoparticles to luminesce. The reduction in size of classically brittle materials reveals a ductile-to-brittle transition. Such a transition, attributed to a reduction in defects, increases elasticity. In the case of silicon, elastic deformation can improve electronic carrier mobility by over 50%, a vital attribute of modern integrated circuits. The scalability of such principles and the changing atomistic processes which contribute to them presents a vitally important field of research. Beginning with the direct observation of dislocations and lattice planes in the 1950s, the transmission electron microscope has been a powerful tool in materials science. More recently, as nanoscale technologies have proliferated modern life, their unique ability to spatially resolve nano- and atomic-scale structures has become a critical component of materials research and characterization. Signals produced by an incident beam of high-energy electrons enables researchers to both image and chemically analyze materials at the atomic scale. Coherently and elastically-scattered electrons can be collected to produce atomic-scale images of a crystalline sample. New specimen stages have enabled routine investigation of samples heated up to 1000 °C and cooled to liquid nitrogen temperatures. MEMS-based transducers allow for sub-nm scale mechanical testing and ultrathin membranes allow study of liquids and gases. Investigation of a myriad of previously "unseeable" processes can now be observed within the TEM, and sometimes something new is found within the old. High-temperature annealing of pure a Si:H films leads to crystallization of the film. Such films provide higher carrier mobility compared to amorphous films, offering improved photovoltaic performance. The annealing process, however, requires exceptionally high temperature (> 600 °C) and time (tens of hours), limiting throughput and costing energy. In an effort to fabricate polycrystalline solar cells at lower cost, large ( 30 nm) silicon nanocrystals were incorporated into hydrogenated amorphous silicon (a Si:H) thin films. When annealed, the embedded nanocrystals were expected to act as heterogeneous nucleation sites and crystallize the surrounding amorphous matrix. When observed in the TEM, an additional and unexpected event was observed. At the boundary between the nanocrystal and amorphous matrix, nanocavities were observed to form. Continued annealing resulted in movement of the cavities away from the nanocrystal while leaving behind a crystalline tail. The origins and fundamental mechanisms of this phenomenon were examined by in-situ heating TEM and ex-situ crystallographic TEM techniques. We demonstrate a mechanism of solid-phase crystallization (SPC) enabled by nanoscale cavities formed at the interface between an hydrogenated amorphous silicon film and embedded 30 nm to 40 nm Si nanocrystals. The nanocavities, 10 nm to 25 nm across, have the unique property of an internal surface that is part amorphous and part crystalline, enabling capillarity-driven diffusion from the amorphous to the crystalline domain. The nanocavities propagate rapidly through the amorphous phase, up to five times faster than the SPC growth rate, while "pulling behind" a crystalline tail. It is shown that twin boundaries exposed on the crystalline surface accelerate crystal growth and influence the direction of nanocavity propagation. The mechanical properties and mechanisms of plasticity in these same silicon nanocubes have also been investigated. The strain-dependent mechanical properties and the underlying mechanisms governing the elastic-plastic response are explored in detail. Elastic strains approaching 7% and flow stresses of 11 GPa were observed, significantly higher than that observed in other nanoscale volumes of Si. In-situ imaging revealed the formation of 5 nm dislocation embryos at 7% strain, giving way at 20% strain to continuous nucleation of leading partial dislocations with {111}-habit at the embryo surface.

Automatic segmentation of triaxial accelerometry signals for falls risk estimation.

PubMed

Redmond, Stephen J; Scalzi, Maria Elena; Narayanan, Michael R; Lord, Stephen R; Cerutti, Sergio; Lovell, Nigel H

2010-01-01

Falls-related injuries in the elderly population represent one of the most significant contributors to rising health care expense in developed countries. In recent years, falls detection technologies have become more common. However, very few have adopted a preferable falls prevention strategy through unsupervised monitoring in the free-living environment. The basis of the monitoring described herein was a self-administered directed-routine (DR) comprising three separate tests measured by way of a waist-mounted triaxial accelerometer. Using features extracted from the manually segmented signals, a reasonable estimate of falls risk can be achieved. We describe here a series of algorithms for automatically segmenting these recordings, enabling the use of the DR assessment in the unsupervised and home environments. The accelerometry signals, from 68 subjects performing the DR, were manually annotated by an observer. Using the proposed signal segmentation routines, an good agreement was observed between the manually annotated markers and the automatically estimated values. However, a decrease in the correlation with falls risk to 0.73 was observed using the automatic segmentation, compared to 0.81 when using markers manually placed by an observer.

New Technique for Retrieving Liquid Water Path over Land using Satellite Microwave Observations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deeter, M.N.; Vivekanandan, J.

2005-03-18

We present a new methodology for retrieving liquid water path over land using satellite microwave observations. As input, the technique exploits the Advanced Microwave Scanning Radiometer for earth observing plan (EOS) (AMSR-E) polarization-difference signals at 37 and 89 GHz. Regression analysis performed on model simulations indicates that over variable atmospheric and surface conditions the polarization-difference signals can be simply parameterized in terms of the surface emissivity polarization difference ({Delta}{var_epsilon}), surface temperature, liquid water path (LWP), and precipitable water vapor (PWV). The resulting polarization-difference parameterization (PDP) enables fast and direct (noniterative) retrievals of LWP with minimal requirements for ancillary data. Single-more » and dual-channel retrieval methods are described and demonstrated. Data gridding is used to reduce the effects of instrumental noise. The methodology is demonstrated using AMSR-E observations over the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site during a six day period in November and December, 2003. Single- and dual-channel retrieval results mostly agree with ground-based microwave retrievals of LWP to within approximately 0.04 mm.« less

National Space Council’s Scott Pace Comments on New Presidential Space Policy, Return to Moon

NASA Image and Video Library

2017-12-11

Executive Secretary of the National Space Council, Scott Pace, comments on the Space Policy Directive-1, signed by President Trump at the White House on Monday, Dec. 11. It directs NASA’s human spaceflight program back to the Moon, as recommended by the Council. The directive calls for NASA to lead an innovative and sustainable program of exploration with commercial and international partners to enable human expansion across the solar system, and to bring back to Earth new knowledge and opportunities for human advancement. This effort will more effectively organize government, private industry, and international efforts toward returning humans on the Moon, and will lay the foundation that will eventually enable human exploration of Mars.

Directing Matter: Toward Atomic-Scale 3D Nanofabrication.

PubMed

Jesse, Stephen; Borisevich, Albina Y; Fowlkes, Jason D; Lupini, Andrew R; Rack, Philip D; Unocic, Raymond R; Sumpter, Bobby G; Kalinin, Sergei V; Belianinov, Alex; Ovchinnikova, Olga S

2016-06-28

Enabling memristive, neuromorphic, and quantum-based computing as well as efficient mainstream energy storage and conversion technologies requires the next generation of materials customized at the atomic scale. This requires full control of atomic arrangement and bonding in three dimensions. The last two decades witnessed substantial industrial, academic, and government research efforts directed toward this goal through various lithographies and scanning-probe-based methods. These technologies emphasize 2D surface structures, with some limited 3D capability. Recently, a range of focused electron- and ion-based methods have demonstrated compelling alternative pathways to achieving atomically precise manufacturing of 3D structures in solids, liquids, and at interfaces. Electron and ion microscopies offer a platform that can simultaneously observe dynamic and static structures at the nano- and atomic scales and also induce structural rearrangements and chemical transformation. The addition of predictive modeling or rapid image analytics and feedback enables guiding these in a controlled manner. Here, we review the recent results that used focused electron and ion beams to create free-standing nanoscale 3D structures, radiolysis, and the fabrication potential with liquid precursors, epitaxial crystallization of amorphous oxides with atomic layer precision, as well as visualization and control of individual dopant motion within a 3D crystal lattice. These works lay the foundation for approaches to directing nanoscale level architectures and offer a potential roadmap to full 3D atomic control in materials. In this paper, we lay out the gaps that currently constrain the processing range of these platforms, reflect on indirect requirements, such as the integration of large-scale data analysis with theory, and discuss future prospects of these technologies.

Directing Matter: Toward Atomic-Scale 3D Nanofabrication

DOE PAGES

Jesse, Stephen; Borisevich, Albina Y.; Fowlkes, Jason D.; ...

2016-05-16

Here we report that enabling memristive, neuromorphic, and quantum based computing as well as efficient mainstream energy storage and conversion technologies requires next generation of materials customized at the atomic scale. This requires full control of atomic arrangement and bonding in three dimensions. The last two decades witnessed substantial industrial, academic, and government research efforts directed towards this goal through various lithographies and scanning probe based methods. These technologies emphasize 2D surface structures, with some limited 3D capability. Recently, a range of focused electron and ion based methods have demonstrated compelling alternative pathways to achieving atomically precise manufacturing of 3Dmore » structures in solids, liquids, and at interfaces. Electron and ion microscopies offer a platform that can simultaneously observe dynamic and static structures at the nano and atomic scales, and also induce structural rearrangements and chemical transformation. The addition of predictive modeling or rapid image analytics and feedback enables guiding these in a controlled manner. Here, we review the recent results that used focused electron and ion beams to create free-standing nanoscale 3D structures, radiolysis and the fabrication potential with liquid precursors, epitaxial crystallization of amorphous oxides with atomic layer precision, as well as visualization and control of individual dopant motion within a 3D crystal lattice. These works lay the foundation for new approaches to directing nanoscale level architectures and offer a potential roadmap to full 3D atomic control in materials. Lastly, in this perspective we lay out the gaps that currently constrain the processing range of these platforms, reflect on indirect requirements, such as the integration of large scale data analysis with theory, and discuss future prospects of these technologies.« less

Solar and Space Physics Science Enabled by Pico and Nano Satellites

NASA Astrophysics Data System (ADS)

Swenson, C.; Fish, C. S.

2012-12-01

The most significant advances in solar and space physics, or Heliophysics, over the next decade are most likely to derive from new observational techniques. The connection between advances in scientific understanding and technology has historically been demonstrated across many disciplines and time. Progress on some of the most compelling scientific problems will most likely occur through multipoint observations within the space environment to understand the coupling between disparate regions: Heliosphere, magnetosphere, ionosphere, thermosphere and mesosphere. Multipoint measurements are also needed to develop understanding of the various scalars or vector field signatures (i.e gradients, divergence) that arise from coupling processes that occur across temporal and spatial scales or within localized regions. The resources that are available over the next decades for all areas of Heliophysics research have limits and it is therefore important that the community be innovative in developing new observational techniques to advance science. One of the most promising new observational techniques becoming available are miniaturized sensors and satellite systems called pico- or nano-satellites and CubeSats. These are enabled by the enormous investment of the commercial, medical, and defense industries in producing highly capable, portable and low-power battery-operated consumer electronics, in-situ composition probes, and novel reconnaissance sensors. The advancements represented by these technologies have direct application in developing pico- or nano-satellites and CubeSats system for Heliophysics research. In this talk we overview the current environment and technologies surrounding these novel small satellites and discuss the types and capabilities of the miniature sensors that are being developed. We discuss how pico- or nano-satellites and CubeSats can be used to address highest priority science identified in the Decadal Survey and the innovations and advancements that are required to make substantial progress.

IC 3639 - A New Bona Fide Compton-Thick AGN Unveiled By NuSTAR

NASA Technical Reports Server (NTRS)

Boorman, Peter G.; Gandhi, P.; Alexander, D. M.; Annuar, A.; Ballantyne, D. R.; Bauer, F.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.;

Properties of X-Ray Flashes from HETE Observations

NASA Astrophysics Data System (ADS)

Ricker, G. R.; HETE Science Team

2005-05-01

Now in its fifth year of operations, HETE continues to provide the observer community with prompt localizations and accurate spectral measurements of GRB sources over a broad energy range, extending from 2-500 keV. As a result of HETE's excellent low energy response, it is uniquely suited to the discovery of X-ray flashes (XRFs). Approximately 1/3 of the ˜20-25 GRBs per year which HETE localizes are XRFs. HETE's localization sample now includes >25 X-ray flashes (XRFs), with redshifts having been established for two: XRF020903 (z=0.25) and XRF030429 (z=2.66). Following on from the original discovery of XRFs by BeppoSAX, HETE has shown that the discovery space for such rapid, soft cosmological transients is quite large: as a class, XRFs (and X-ray rich GRBs) are more numerous than are classical GRBs. Although XRFs may well be related to GRBs, there are indications that XRFs have spectral peaks (in ν Fν ) that can extend down to, or even below, 1 keV. Although the BAT instrument on Swift cannot directly explore this low energy range, the slewing of Swift to HETE-discovered XRFs will enable Swift's XRT to conduct target-of-opportunity followup observations. These Swift XRT followup observations are a powerful means of establishing ˜3-5 arcsecond localizations from the X-ray afterglows, thus enabling sensitive optical and IR searches for counterparts and subsequent redshift measurements. Properties of the sample of HETE-discovered XRFs will be reviewed, and the implications of the HETE sample for the planning of future missions will be discussed. The HETE scientific team includes participants from France, Japan, Brazil, India, Italy, and the USA. This research was supported in the USA by NASA contracts NASW-4690 and NAS8-39073.

Constructive, Collaborative, Contextual, and Self-Directed Learning in Surface Anatomy Education

ERIC Educational Resources Information Center

Bergman, Esther M.; Sieben, Judith M.; Smailbegovic, Ida; de Bruin, Anique B. H.; Scherpbier, Albert J. J. A.; van der Vleuten, Cees P. M.

2013-01-01

Anatomy education often consists of a combination of lectures and laboratory sessions, the latter frequently including surface anatomy. Studying surface anatomy enables students to elaborate on their knowledge of the cadaver's static anatomy by enabling the visualization of structures, especially those of the musculoskeletal system, move and…

Ocean data management in OMP Data Service

NASA Astrophysics Data System (ADS)

Fleury, Laurence; André, François; Belmahfoud, Nizar; Boichard, Jean-Luc; Brissebrat, Guillaume; Ferré, Hélène; Mière, Arnaud

2014-05-01

The Observatoire Midi-Pyrénées Data Service (SEDOO) is a development team, dedicated to environmental data management and dissemination application set up, in the framework of intensive field campaigns and long term observation networks. SEDOO developped some applications dealing with ocean data only, but also generic databases that enable to store and distribute multidisciplinary datasets. SEDOO is in charge of the in situ data management and the data portal for international and multidisciplinary programmes as large as African Monsoon Multidisciplinary Analyses (AMMA) and Mediterranean Integrated STudies at Regional And Local Scales (MISTRALS). The AMMA and MISTRALS databases are distributed and the data portals enable to access datasets managed by other data centres (IPSL, CORIOLIS...) through interoperability protocols (OPeNDAP, xml requests...). AMMA and MISTRALS metadata (data description) are standardized and comply with international standards (ISO 19115-19139; INSPIRE European Directive; Global Change Master Directory Thesaurus). Most of the AMMA and MISTRALS in situ ocean data sets are homogenized and inserted in a relational database, in order to enable accurate data selection and download of different data sets in a shared format. Data selection criteria are location, period, physical property name, physical property range... The data extraction procedure include format output selection among CSV, NetCDF, Nasa Ames... The AMMA database - http://database.amma-international.org/ - contains field campaign observations in the Guinea Gulf (EGEE 2005-2007) and Atlantic Tropical Ocean (AEROSE-II 2006...), as well as long term monitoring data (PIRATA, ARGO...). Operational analysis (MERCATOR) and satellite products (TMI, SSMI...) are managed by IPSL data centre and can be accessed too. They have been projected over regular latitude-longitude grids and converted into the NetCDF format. The MISTRALS data portal - http://mistrals.sedoo.fr/ - enables to access ocean datasets produced by the contributing programmes: Hydrological cycle in the Mediterranean eXperiment (HyMeX), Chemistry-Aerosol Mediterranean eXperiment (ChArMEx), Marine Mediterranean eXperiment (MERMeX)... The programmes include many field campaigns from 2011 to 2015, collecting general and specific properties. Long term monitoring networks, like Mediterranean Ocean Observing System on Environment (MOOSE) or Mediterranean Eurocentre for Underwater Sciences and Technologies (MEUST-SE), contribute to the MISTRALS data portal as well. Relevant model outputs and satellite products managed by external data centres (IPSL, ENEA...) can be accessed too. SEDOO manages the SSS (Sea Surface Salinity) national observation service data: http://sss.sedoo.fr/. SSS aims at collecting, validating, archiving and distributing in situ SSS measurements derived from Voluntary Observing Ship programs. The SSS data user interface enables to built multicriteria data request and download relevant datasets. SEDOO contributes to the SOLWARA project that aims at understanding the oceanic circulation in the Coral Sea and the Solomon Sea and their role in both the climate system and the oceanic chemistry. The research programme include in situ measurements, numerical modelling and compiled analyses of past data. The website http://thredds.sedoo.fr/solwara/ enables to access, visualize and download Solwara gridded data and model simulations, using Thredds associated services (OPEnDAP, NCSS and WMS). In order to improve the application user-friendliness, SSS and SOLWARA web interfaces are JEE applications build with GWT Framework, and share many modules.

Colors of Alien Worlds from Direct Imaging Exoplanet Missions

NASA Astrophysics Data System (ADS)

Hu, Renyu

2016-01-01

Future direct-imaging exoplanet missions such as WFIRST will measure the reflectivity of exoplanets at visible wavelengths. Most of the exoplanets to be observed will be located further away from their parent stars than is Earth from the Sun. These "cold" exoplanets have atmospheric environments conducive for the formation of water and/or ammonia clouds, like Jupiter in the Solar System. I find the mixing ratio of methane and the pressure level of the uppermost cloud deck on these planets can be uniquely determined from their reflection spectra, with moderate spectral resolution, if the cloud deck is between 0.6 and 1.5 bars. The existence of this unique solution is useful for exoplanet direct imaging missions for several reasons. First, the weak bands and strong bands of methane enable the measurement of the methane mixing ratio and the cloud pressure, although an overlying haze layer can bias the estimate of the latter. Second, the cloud pressure, once derived, yields an important constraint on the internal heat flux from the planet, and thus indicating its thermal evolution. Third, water worlds having H2O-dominated atmospheres are likely to have water clouds located higher than the 10-3 bar pressure level, and muted spectral absorption features. These planets would occupy a confined phase space in the color-color diagrams, likely distinguishable from H2-rich giant exoplanets by broadband observations. Therefore, direct-imaging exoplanet missions may offer the capability to broadly distinguish H2-rich giant exoplanets versus H2O-rich super-Earth exoplanets, and to detect ammonia and/or water clouds and methane gas in their atmospheres.

Neonatal and maternal outcomes of successful manual rotation to correct malposition of the fetal head; A retrospective and prospective observational study

PubMed Central

Tempest, Nicola; McGuinness, Naomi; Lane, Steven; Hapangama, Dharani K.

2017-01-01

Objective To evaluate the neonatal and maternal outcomes associated with successful operative vaginal births assisted by manual rotation. Design Prospective and retrospective observational study. Setting Delivery suite in a tertiary referral teaching hospital in England. Population A cohort of 2,426 consecutive operative births, in the second stage of labour, complicated with malposition of the fetal head during 2006–2013. Methods Outcomes of all births successfully assisted by manual rotation followed by direct traction instruments were compared with other methods of operative birth for fetal malposition in the second stage of labour (rotational ventouse, Kielland forceps and caesarean section). Main outcome measures Associated neonatal outcomes (admission to the special care baby unit, low cord pH, low Apgar and shoulder dystocia) and maternal outcomes (massive obstetric haemorrhage (blood loss of >1500ml) and obstetric anal sphincter injury). Results Births successfully assisted with manual rotation followed by direct traction instruments, resulted in 10% (36/346) of the babies being admitted to the Special Care Baby Unit, 4.9% (17/349) shoulder dystocia, 2% (7/349) massive obstetric haemorrhage and 1.7% (6/349) obstetric anal sphincter injury, similar to other methods of rotational births. Conclusions Adverse neonatal and maternal outcomes associated with successful manual rotations followed by direct traction instruments were comparable to traditional methods of operative births. There is an urgent need to standardise the practice (guidance, training) and documentation of manual rotation followed by direct traction instrumental deliveries that will enable assessment of its efficacy and the absolute safety in achieving a vaginal birth. PMID:28489924

Neonatal and maternal outcomes of successful manual rotation to correct malposition of the fetal head; A retrospective and prospective observational study.

PubMed

Tempest, Nicola; McGuinness, Naomi; Lane, Steven; Hapangama, Dharani K

2017-01-01

To evaluate the neonatal and maternal outcomes associated with successful operative vaginal births assisted by manual rotation. Prospective and retrospective observational study. Delivery suite in a tertiary referral teaching hospital in England. A cohort of 2,426 consecutive operative births, in the second stage of labour, complicated with malposition of the fetal head during 2006-2013. Outcomes of all births successfully assisted by manual rotation followed by direct traction instruments were compared with other methods of operative birth for fetal malposition in the second stage of labour (rotational ventouse, Kielland forceps and caesarean section). Associated neonatal outcomes (admission to the special care baby unit, low cord pH, low Apgar and shoulder dystocia) and maternal outcomes (massive obstetric haemorrhage (blood loss of >1500ml) and obstetric anal sphincter injury). Births successfully assisted with manual rotation followed by direct traction instruments, resulted in 10% (36/346) of the babies being admitted to the Special Care Baby Unit, 4.9% (17/349) shoulder dystocia, 2% (7/349) massive obstetric haemorrhage and 1.7% (6/349) obstetric anal sphincter injury, similar to other methods of rotational births. Adverse neonatal and maternal outcomes associated with successful manual rotations followed by direct traction instruments were comparable to traditional methods of operative births. There is an urgent need to standardise the practice (guidance, training) and documentation of manual rotation followed by direct traction instrumental deliveries that will enable assessment of its efficacy and the absolute safety in achieving a vaginal birth.

Digital direct electron imaging of energy-filtered electron backscatter diffraction patterns

NASA Astrophysics Data System (ADS)

Vespucci, S.; Winkelmann, A.; Naresh-Kumar, G.; Mingard, K. P.; Maneuski, D.; Edwards, P. R.; Day, A. P.; O'Shea, V.; Trager-Cowan, C.

2015-11-01

Electron backscatter diffraction is a scanning electron microscopy technique used to obtain crystallographic information on materials. It allows the nondestructive mapping of crystal structure, texture, and strain with a lateral and depth resolution on the order of tens of nanometers. Electron backscatter diffraction patterns (EBSPs) are presently acquired using a detector comprising a scintillator coupled to a digital camera, and the crystallographic information obtainable is limited by the conversion of electrons to photons and then back to electrons again. In this article we will report the direct acquisition of energy-filtered EBSPs using a digital complementary metal-oxide-semiconductor hybrid pixel detector, Timepix. We show results from a range of samples with different mass and density, namely diamond, silicon, and GaN. Direct electron detection allows the acquisition of EBSPs at lower (≤5 keV) electron beam energies. This results in a reduction in the depth and lateral extension of the volume of the specimen contributing to the pattern and will lead to a significant improvement in lateral and depth resolution. Direct electron detection together with energy filtering (electrons having energy below a specific value are excluded) also leads to an improvement in spatial resolution but in addition provides an unprecedented increase in the detail in the acquired EBSPs. An increase in contrast and higher-order diffraction features are observed. In addition, excess-deficiency effects appear to be suppressed on energy filtering. This allows the fundamental physics of pattern formation to be interrogated and will enable a step change in the use of electron backscatter diffraction (EBSD) for crystal phase identification and the mapping of strain. The enhancement in the contrast in high-pass energy-filtered EBSD patterns is found to be stronger for lighter, less dense materials. The improved contrast for such materials will enable the application of the EBSD technique to be expanded to materials for which conventional EBSD analysis is not presently practicable.

Transit Recovery of Kepler-167e: Providing JWST with an Unprecedented Jupiter-analog Exoplanet Target

NASA Astrophysics Data System (ADS)

Dalba, Paul; Muirhead, Philip; Tamburo, Patrick

2018-05-01

The Kepler Mission has uncovered a handful of long-period transiting exoplanets that orbit in the cold outer reaches of their systems, despite their low transit probabilities. Recent work suggests that cold gas giant exoplanet atmospheres are amenable to transmission spectroscopy (the analysis of the transit depth versus wavelength) enabling novel tests of planetary formation and evolution theories. Of particular scientific interest is Kepler-167e, a low-eccentricity Jupiter-analog exoplanet with a 1,071-day orbital period residing well beyond the snow-line. Transmission spectroscopy of Kepler-167e from JWST can reveal the composition of this planet's atmosphere, constrain its heavy-element abundance, and identify atmospheric photochemical processes. JWST characterization also enables unprecedented direct comparison with Jupiter and Saturn, which show a striking diversity in physical properties that is best investigated through comparative exoplanetology. Since Kepler only observed two transits of Kepler-167e, it is not known if this exoplanet exhibits transit timing variations (TTVs). About half of Kepler's long-period exoplanets have TTVs of up to 40 hours. Such a large uncertainty jeopardizes attempts to characterize the atmosphere of this unique Jovian exoplanet with JWST. To mitigate this risk, the upcoming third transit of Kepler-167e must be observed to test for TTVs. We propose a simple 10-hour, single-channel observation to capture ingress or egress of the next transit of Kepler-167e in December 2018. In the absence of TTVs, our observation will reduce the ephemeris uncertainty from an unknown value to approximately 3 minutes, thereby removing the risk in future transit observations with JWST. The excellent photometric precision of Spitzer is sufficient to identify the transit of Kepler-167e. Given the timing and nature of this program, Spitzer is the only observatory--on the ground or in space--that can make this pivotal observation.

Deep-sea observations at hydrocarbon drilling locations: Contributions from the SERPENT Project after 120 field visits

NASA Astrophysics Data System (ADS)

Gates, Andrew R.; Benfield, Mark C.; Booth, David J.; Fowler, Ashley M.; Skropeta, Danielle; Jones, Daniel O. B.

2017-03-01

The SERPENT Project has been running for over ten years. In this time scientists from universities and research institutions have made more than 120 visits to oil rigs, drill ships and survey vessels operated by 16 oil companies, in order to work with the industry's Remotely Operated Vehicles (ROV). Visits have taken place in Europe, North and South America, Africa and Australasia at water depths from 100 m to nearly 3000 m. The project has directly produced >40 peer reviewed publications and data from the project's >2600 entry online image and video archive have been used in many others. The aim of this paper is to highlight examples of how valuable data can be obtained through collaboration with hydrocarbon exploration and production companies to use existing industry infrastructure to increase scientific discovery in unexplored areas and augment environmental monitoring of industrial activity. The large number of industry ROVs operating globally increases chance encounters with large, enigmatic marine organisms. SERPENT video observations include the deepest known records of species previously considered epipelagic such as scalloped hammerhead (Sphyrna lewini) and southern sunfish (Mola ramsayi) and the first in situ observations of pelagic species such as oarfish (Regalecus glesne). Such observations enable improvements to distribution records and description of behaviour of poorly understood species. Specimen collection has been used for taxonomic descriptions, functional studies and natural products chemistry research. Anthropogenic effects been assessed at the local scale using in situ observations and sample collection at the time of drilling operations and subsequent visits have enabled study of recovery from drilling. Future challenges to be addressed using the SERPENT approach include ensuring unique faunal observations by industry ROV operators are reported, further study of recovery from deep-water drilling activity and to carry out in situ studies to improve the understanding of potential future decommissioning of obsolete hydrocarbon infrastructure.

Efficient visibility encoding for dynamic illumination in direct volume rendering.

PubMed

Kronander, Joel; Jönsson, Daniel; Löw, Joakim; Ljung, Patric; Ynnerman, Anders; Unger, Jonas

2012-03-01

We present an algorithm that enables real-time dynamic shading in direct volume rendering using general lighting, including directional lights, point lights, and environment maps. Real-time performance is achieved by encoding local and global volumetric visibility using spherical harmonic (SH) basis functions stored in an efficient multiresolution grid over the extent of the volume. Our method enables high-frequency shadows in the spatial domain, but is limited to a low-frequency approximation of visibility and illumination in the angular domain. In a first pass, level of detail (LOD) selection in the grid is based on the current transfer function setting. This enables rapid online computation and SH projection of the local spherical distribution of visibility information. Using a piecewise integration of the SH coefficients over the local regions, the global visibility within the volume is then computed. By representing the light sources using their SH projections, the integral over lighting, visibility, and isotropic phase functions can be efficiently computed during rendering. The utility of our method is demonstrated in several examples showing the generality and interactive performance of the approach.

Petaminer: Using ROOT for efficient data storage in MySQL database

NASA Astrophysics Data System (ADS)

Cranshaw, J.; Malon, D.; Vaniachine, A.; Fine, V.; Lauret, J.; Hamill, P.

2010-04-01

High Energy and Nuclear Physics (HENP) experiments store Petabytes of event data and Terabytes of calibration data in ROOT files. The Petaminer project is developing a custom MySQL storage engine to enable the MySQL query processor to directly access experimental data stored in ROOT files. Our project is addressing the problem of efficient navigation to PetaBytes of HENP experimental data described with event-level TAG metadata, which is required by data intensive physics communities such as the LHC and RHIC experiments. Physicists need to be able to compose a metadata query and rapidly retrieve the set of matching events, where improved efficiency will facilitate the discovery process by permitting rapid iterations of data evaluation and retrieval. Our custom MySQL storage engine enables the MySQL query processor to directly access TAG data stored in ROOT TTrees. As ROOT TTrees are column-oriented, reading them directly provides improved performance over traditional row-oriented TAG databases. Leveraging the flexible and powerful SQL query language to access data stored in ROOT TTrees, the Petaminer approach enables rich MySQL index-building capabilities for further performance optimization.

Development of a digital mobile solar tracker

NASA Astrophysics Data System (ADS)

Baidar, S.; Kille, N.; Ortega, I.; Sinreich, R.; Thomson, D.; Hannigan, J.; Volkamer, R.

2015-11-01

We have constructed and deployed a fast digital solar tracker aboard a moving ground-based platform. The tracker consists of two rotating mirrors, a lens, an imaging camera, and a motion compensation system that provides the Euler angles of the mobile platform in real time. The tracker can be simultaneously coupled to UV-Vis and FTIR spectrometers making it a versatile tool to measure the absorption of trace gases using solar incoming radiation. The integrated system allows the tracker to operate autonomously while the mobile laboratory is in motion. Mobile direct sun Differential Optical Absorption Spectroscopy (mobile DS-DOAS) observations using this tracker were conducted during summer 2014 as part of the Front Range Photochemistry and Pollution Experiment (FRAPPE) in Colorado, USA. We demonstrate an angular precision of 0.052° (about 1/10 of the solar disk diameter) during research drives, and verify this tracking precision from measurements of the center to limb darkening (CLD, the changing appearance of Fraunhofer lines) in the mobile DS-DOAS spectra. The high photon flux from direct sun observation enables measurements of nitrogen dioxide (NO2) slant columns with high temporal resolution, and reveals spatial detail in the variations of NO2 vertical column densities (VCDs). The NO2 VCD from DS-DOAS is compared with a co-located MAX-DOAS instrument. Overall good agreement is observed amid a highly heterogeneous air mass.

Development of a digital mobile solar tracker

NASA Astrophysics Data System (ADS)

Baidar, Sunil; Kille, Natalie; Ortega, Ivan; Sinreich, Roman; Thomson, David; Hannigan, James; Volkamer, Rainer

2016-03-01

We have constructed and deployed a fast digital solar tracker aboard a moving ground-based platform. The tracker consists of two rotating mirrors, a lens, an imaging camera, and a motion compensation system that provides the Euler angles of the mobile platform in real time. The tracker can be simultaneously coupled to UV-Vis and Fourier transform infrared spectrometers, making it a versatile tool to measure the absorption of trace gases using solar incoming radiation. The integrated system allows the tracker to operate autonomously while the mobile laboratory is in motion. Mobile direct sun differential optical absorption spectroscopy (mobile DS-DOAS) observations using this tracker were conducted during summer 2014 as part of the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) in Colorado, USA. We demonstrate an angular precision of 0.052° (about 1/10 of the solar disk diameter) during research drives and verify this tracking precision from measurements of the center to limb darkening (CLD, the changing appearance of Fraunhofer lines) in the mobile DS-DOAS spectra. The high photon flux from direct sun observation enables measurements of nitrogen dioxide (NO2) slant columns with high temporal resolution and reveals spatial detail in the variations of NO2 vertical column densities (VCDs). The NO2 VCD from DS-DOAS is compared with a co-located MAX-DOAS instrument. Overall good agreement is observed amid a highly heterogeneous air mass.

Environmental Profile of a Community's Health (EPOCH): An Instrument to Measure Environmental Determinants of Cardiovascular Health in Five Countries

PubMed Central

Chow, Clara K.; Lock, Karen; Madhavan, Manisha; Corsi, Daniel J.; Gilmore, Anna B.; Subramanian, S. V.; Li, Wei; Swaminathan, Sumathi; Lopez-Jaramillo, Patricio; Avezum, Alvaro; Lear, Scott A.; Dagenais, Gilles; Teo, Koon; McKee, Martin; Yusuf, Salim

2010-01-01

Background The environment in which people live is known to be important in influencing diet, physical activity, smoking, psychosocial and other risk factors for cardiovascular (CV) disease. However no instrument exists that evaluates communities for these multiple environmental factors and is suitable for use across different communities, regions and countries. This report describes the design and reliability of an instrument to measure environmental determinants of CV risk factors. Method/Principal Findings The Environmental Profile of Community Health (EPOCH) instrument comprises two parts: (I) an assessment of the physical environment, and (II) an interviewer-administered questionnaire to collect residents' perceptions of their community. We examined the inter-rater reliability amongst 3 observers from each region of the direct observation component of the instrument (EPOCH I) in 93 rural and urban communities in 5 countries (Canada, Colombia, Brazil, China and India). Data collection using the EPOCH instrument was feasible in all communities. Reliability of the instrument was excellent (Intraclass Correlation Coefficient - ICC>0.75) for 24 of 38 items and fair to good (ICC 0.4–0.75) for 14 of 38 items. Conclusion This report shows data collection with the EPOCH instrument is feasible and direct observation of community measures reliable. The EPOCH instrument will enable further research on environmental determinants of health for population studies from a broad range of settings. PMID:21170320

Multi-Sensor Aerosol Products Sampling System

NASA Technical Reports Server (NTRS)

Petrenko, M.; Ichoku, C.; Leptoukh, G.

2011-01-01

Global and local properties of atmospheric aerosols have been extensively observed and measured using both spaceborne and ground-based instruments, especially during the last decade. Unique properties retrieved by the different instruments contribute to an unprecedented availability of the most complete set of complimentary aerosol measurements ever acquired. However, some of these measurements remain underutilized, largely due to the complexities involved in analyzing them synergistically. To characterize the inconsistencies and bridge the gap that exists between the sensors, we have established a Multi-sensor Aerosol Products Sampling System (MAPSS), which consistently samples and generates the spatial statistics (mean, standard deviation, direction and rate of spatial variation, and spatial correlation coefficient) of aerosol products from multiple spacebome sensors, including MODIS (on Terra and Aqua), MISR, OMI, POLDER, CALIOP, and SeaWiFS. Samples of satellite aerosol products are extracted over Aerosol Robotic Network (AERONET) locations as well as over other locations of interest such as those with available ground-based aerosol observations. In this way, MAPSS enables a direct cross-characterization and data integration between Level-2 aerosol observations from multiple sensors. In addition, the available well-characterized co-located ground-based data provides the basis for the integrated validation of these products. This paper explains the sampling methodology and concepts used in MAPSS, and demonstrates specific examples of using MAPSS for an integrated analysis of multiple aerosol products.

Dual-dimensional microscopy: real-time in vivo three-dimensional observation method using high-resolution light-field microscopy and light-field display.

PubMed

Kim, Jonghyun; Moon, Seokil; Jeong, Youngmo; Jang, Changwon; Kim, Youngmin; Lee, Byoungho

2018-06-01

Here, we present dual-dimensional microscopy that captures both two-dimensional (2-D) and light-field images of an in-vivo sample simultaneously, synthesizes an upsampled light-field image in real time, and visualizes it with a computational light-field display system in real time. Compared with conventional light-field microscopy, the additional 2-D image greatly enhances the lateral resolution at the native object plane up to the diffraction limit and compensates for the image degradation at the native object plane. The whole process from capturing to displaying is done in real time with the parallel computation algorithm, which enables the observation of the sample's three-dimensional (3-D) movement and direct interaction with the in-vivo sample. We demonstrate a real-time 3-D interactive experiment with Caenorhabditis elegans. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Weina; Hellinga, Homme W.; Beese, Lorena S.

Even though high-fidelity polymerases copy DNA with remarkable accuracy, some base-pair mismatches are incorporated at low frequency, leading to spontaneous mutagenesis. Using high-resolution X-ray crystallographic analysis of a DNA polymerase that catalyzes replication in crystals, we observe that a C {center_dot} A mismatch can mimic the shape of cognate base pairs at the site of incorporation. This shape mimicry enables the mismatch to evade the error detection mechanisms of the polymerase, which would normally either prevent mismatch incorporation or promote its nucleolytic excision. Movement of a single proton on one of the mismatched bases alters the hydrogen-bonding pattern such thatmore » a base pair forms with an overall shape that is virtually indistinguishable from a canonical, Watson-Crick base pair in double-stranded DNA. These observations provide structural evidence for the rare tautomer hypothesis of spontaneous mutagenesis, a long-standing concept that has been difficult to demonstrate directly.« less

Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave

PubMed Central

Gershman, Daniel J.; F-Viñas, Adolfo; Dorelli, John C.; Boardsen, Scott A.; Avanov, Levon A.; Bellan, Paul M.; Schwartz, Steven J.; Lavraud, Benoit; Coffey, Victoria N.; Chandler, Michael O.; Saito, Yoshifumi; Paterson, William R.; Fuselier, Stephen A.; Ergun, Robert E.; Strangeway, Robert J.; Russell, Christopher T.; Giles, Barbara L.; Pollock, Craig J.; Torbert, Roy B.; Burch, James L.

2017-01-01

Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA's Magnetospheric Multiscale (MMS) mission, we utilize Earth's magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations. PMID:28361881

Electron spin resonance and spin-valley physics in a silicon double quantum dot.

PubMed

Hao, Xiaojie; Ruskov, Rusko; Xiao, Ming; Tahan, Charles; Jiang, HongWen

2014-05-14

Silicon quantum dots are a leading approach for solid-state quantum bits. However, developing this technology is complicated by the multi-valley nature of silicon. Here we observe transport of individual electrons in a silicon CMOS-based double quantum dot under electron spin resonance. An anticrossing of the driven dot energy levels is observed when the Zeeman and valley splittings coincide. A detected anticrossing splitting of 60 MHz is interpreted as a direct measure of spin and valley mixing, facilitated by spin-orbit interaction in the presence of non-ideal interfaces. A lower bound of spin dephasing time of 63 ns is extracted. We also describe a possible experimental evidence of an unconventional spin-valley blockade, despite the assumption of non-ideal interfaces. This understanding of silicon spin-valley physics should enable better control and read-out techniques for the spin qubits in an all CMOS silicon approach.

Nonlinear two-dimensional terahertz photon echo and rotational spectroscopy in the gas phase.

PubMed

Lu, Jian; Zhang, Yaqing; Hwang, Harold Y; Ofori-Okai, Benjamin K; Fleischer, Sharly; Nelson, Keith A

2016-10-18

Ultrafast 2D spectroscopy uses correlated multiple light-matter interactions for retrieving dynamic features that may otherwise be hidden under the linear spectrum; its extension to the terahertz regime of the electromagnetic spectrum, where a rich variety of material degrees of freedom reside, remains an experimental challenge. We report a demonstration of ultrafast 2D terahertz spectroscopy of gas-phase molecular rotors at room temperature. Using time-delayed terahertz pulse pairs, we observe photon echoes and other nonlinear signals resulting from molecular dipole orientation induced by multiple terahertz field-dipole interactions. The nonlinear time domain orientation signals are mapped into the frequency domain in 2D rotational spectra that reveal J-state-resolved nonlinear rotational dynamics. The approach enables direct observation of correlated rotational transitions and may reveal rotational coupling and relaxation pathways in the ground electronic and vibrational state.

NELIOTA: First temperature measurement of lunar impact flashes

NASA Astrophysics Data System (ADS)

Bonanos, A. Z.; Avdellidou, C.; Liakos, A.; Xilouris, E. M.; Dapergolas, A.; Koschny, D.; Bellas-Velidis, I.; Boumis, P.; Charmandaris, V.; Fytsilis, A.; Maroussis, A.

2018-04-01

We report the first scientific results from the NELIOTA (NEO Lunar Impacts and Optical TrAnsients) project, which has recently begun lunar monitoring observations with the 1.2-m Kryoneri telescope. NELIOTA aims to detect faint impact flashes produced by near-Earth meteoroids and asteroids and thereby help constrain the size-frequency distribution of near-Earth objects in the decimeter to meter range. The NELIOTA setup, consisting of two fast-frame cameras observing simultaneously in the R and I bands, enables - for the first time - direct analytical calculation of the flash temperatures. We present the first ten flashes detected, for which we find temperatures in the range 1600 to 3100 K, in agreement with theoretical values. Two of these flashes were detected on multiple frames in both filters and therefore yield the first measurements of the temperature drop for lunar flashes. In addition, we compute the impactor masses, which range between 100 g and 50 kg.

Time-resolved two-window measurement of Wigner functions for coherent backscatter from a turbid medium

NASA Astrophysics Data System (ADS)

Reil, Frank; Thomas, John E.

2002-05-01

For the first time we are able to observe the time-resolved Wigner function of enhanced backscatter from a random medium using a novel two-window technique. This technique enables us to directly verify the phase-conjugating properties of random media. An incident divergent beam displays a convergent enhanced backscatter cone. We measure the joint position and momentum (x, p) distributions of the light field as a function of propagation time in the medium. The two-window technique allows us to independently control the resolutions for position and momentum, thereby surpassing the uncertainty limit associated with Fourier transform pairs. By using a low-coherence light source in a heterodyne detection scheme, we observe enhanced backscattering resolved by path length in the random medium, providing information about the evolution of optical coherence as a function of penetration depth in the random medium.

Observing random walks of atoms in buffer gas through resonant light absorption

NASA Astrophysics Data System (ADS)

Aoki, Kenichiro; Mitsui, Takahisa

2016-07-01

Using resonant light absorption, random-walk motions of rubidium atoms in nitrogen buffer gas are observed directly. The transmitted light intensity through atomic vapor is measured, and its spectrum is obtained, down to orders of magnitude below the shot-noise level to detect fluctuations caused by atomic motions. To understand the measured spectra, the spectrum for atoms performing random walks in a Gaussian light beam is computed, and its analytical form is obtained. The spectrum has 1 /f2 (f is frequency) behavior at higher frequencies, crossing over to a different, but well-defined, behavior at lower frequencies. The properties of this theoretical spectrum agree excellently with the measured spectrum. This understanding also enables us to obtain the diffusion constant, the photon cross section of atoms in buffer gas, and the atomic number density from a single spectral measurement. We further discuss other possible applications of our experimental method and analysis.

Parsimonious description for predicting high-dimensional dynamics

PubMed Central

Hirata, Yoshito; Takeuchi, Tomoya; Horai, Shunsuke; Suzuki, Hideyuki; Aihara, Kazuyuki

2015-01-01

When we observe a system, we often cannot observe all its variables and may have some of its limited measurements. Under such a circumstance, delay coordinates, vectors made of successive measurements, are useful to reconstruct the states of the whole system. Although the method of delay coordinates is theoretically supported for high-dimensional dynamical systems, practically there is a limitation because the calculation for higher-dimensional delay coordinates becomes more expensive. Here, we propose a parsimonious description of virtually infinite-dimensional delay coordinates by evaluating their distances with exponentially decaying weights. This description enables us to predict the future values of the measurements faster because we can reuse the calculated distances, and more accurately because the description naturally reduces the bias of the classical delay coordinates toward the stable directions. We demonstrate the proposed method with toy models of the atmosphere and real datasets related to renewable energy. PMID:26510518

Monte Carlo modeling of atomic oxygen attack of polymers with protective coatings on LDEF

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Degroh, Kim K.; Sechkar, Edward A.

1992-01-01

Characterization of the behavior of atomic oxygen interaction with materials on the Long Duration Exposure Facility (LDEF) will assist in understanding the mechanisms involved, and will lead to improved reliability in predicting in-space durability of materials based on ground laboratory testing. A computational simulation of atomic oxygen interaction with protected polymers was developed using Monte Carlo techniques. Through the use of assumed mechanistic behavior of atomic oxygen and results of both ground laboratory and LDEF data, a predictive Monte Carlo model was developed which simulates the oxidation processes that occur on polymers with applied protective coatings that have defects. The use of high atomic oxygen fluence-directed ram LDEF results has enabled mechanistic implications to be made by adjusting Monte Carlo modeling assumptions to match observed results based on scanning electron microscopy. Modeling assumptions, implications, and predictions are presented, along with comparison of observed ground laboratory and LDEF results.

Direct observation of electron emission and recombination processes by time domain measurements of charge pumping current

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hori, Masahiro, E-mail: hori@eng.u-toyama.ac.jp; Watanabe, Tokinobu; Ono, Yukinori

2015-01-26

To analyze the charge pumping (CP) sequence in detail, the source/drain electron current and the substrate hole current under the CP mode of transistors are simultaneously monitored in the time domain. Peaks are observed in both the electron and hole currents, which are, respectively, attributed to the electron emission from the interface defects and to the recombination with holes. The peak caused by the electron emission is found to consist of two components, strongly suggesting that the present time-domain measurement can enable us to resolve different kinds of interface defects. Investigating the correlation between the number of emitted and recombinedmore » electrons reveals that only one of the two components contributes to the CP current for the gate-pulse fall time from 6.25 × 10{sup −4} to 1.25 × 10{sup −2} s.« less

Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave.

PubMed

Gershman, Daniel J; F-Viñas, Adolfo; Dorelli, John C; Boardsen, Scott A; Avanov, Levon A; Bellan, Paul M; Schwartz, Steven J; Lavraud, Benoit; Coffey, Victoria N; Chandler, Michael O; Saito, Yoshifumi; Paterson, William R; Fuselier, Stephen A; Ergun, Robert E; Strangeway, Robert J; Russell, Christopher T; Giles, Barbara L; Pollock, Craig J; Torbert, Roy B; Burch, James L

2017-03-31

Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA's Magnetospheric Multiscale (MMS) mission, we utilize Earth's magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations.

Coarse-Grained Simulation of Solvated Cellulose Ib Microfibril

NASA Astrophysics Data System (ADS)

Fan, Bingxin; Maranas, Janna; Zhong, Linghao; Zhen Zhao Collaboration

2013-03-01

We construct a coarse-grained (CG) model of cellulose microfibrils in water. The force field is derived from atomistic simulation of a 40 glucose-unit-long microfibril by requiring consistency between the chain configuration, intermolecular packing and hydrogen bonding of the two levels of modeling. Intermolecular interactions such as hydrogen bonding are added sequentially until the force field holds the microfibril crystal structure. This stepwise process enables us to evaluate the importance of each potential and provides insight to ordered and disordered regions. We simulate cellulose microfibrils with 100 to 400 residues, comparable to the smallest observed microfibrils. Microfibrils longer than 100nm would form a bending region along their longitudinal direction. Multiple bends are observed in the microfibril containing 400 residues. Although the cause is not clear, the bending regions may provide us insights about the periodicity and the behavior of the disordered regions in the microfibril.

Direct Observation of the Surface Segregation of Cu in Pd by Time-Resolved Positron-Annihilation-Induced Auger Electron Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayer, J.; Hugenschmidt, C.; Schreckenbach, K.

2010-11-12

Density functional theory calculations predict the surface segregation of Cu in the second atomic layer of Pd which has not been unambiguously confirmed by experiment so far. We report measurements on Pd surfaces covered with three and six monolayers of Cu using element selective positron-annihilation-induced Auger electron spectroscopy (PAES) which is sensitive to the topmost atomic layer. Moreover, time-resolved PAES, which was applied for the first time, enables the investigation of the dynamics of surface atoms and hence the observation of the segregation process. The time constant for segregation was experimentally determined to {tau}=1.38(0.21) h, and the final segregated configurationmore » was found to be consistent with calculations. Time-dependent PAES is demonstrated to be a novel element selective technique applicable for the investigation of, e.g., heterogeneous catalysis, corrosion, or surface alloying.« less

Direct Observation of the Surface Segregation of Cu in Pd by Time-Resolved Positron-Annihilation-Induced Auger Electron Spectroscopy

NASA Astrophysics Data System (ADS)

Mayer, J.; Hugenschmidt, C.; Schreckenbach, K.

2010-11-01

Density functional theory calculations predict the surface segregation of Cu in the second atomic layer of Pd which has not been unambiguously confirmed by experiment so far. We report measurements on Pd surfaces covered with three and six monolayers of Cu using element selective positron-annihilation-induced Auger electron spectroscopy (PAES) which is sensitive to the topmost atomic layer. Moreover, time-resolved PAES, which was applied for the first time, enables the investigation of the dynamics of surface atoms and hence the observation of the segregation process. The time constant for segregation was experimentally determined to τ=1.38(0.21)h, and the final segregated configuration was found to be consistent with calculations. Time-dependent PAES is demonstrated to be a novel element selective technique applicable for the investigation of, e.g., heterogeneous catalysis, corrosion, or surface alloying.

Adoption of safety eyewear among citrus harvesters in rural Florida.

PubMed

Monaghan, Paul F; Bryant, Carol A; McDermott, Robert J; Forst, Linda S; Luque, John S; Contreras, Ricardo B

2012-06-01

The community-based prevention marketing program planning framework was used to adapt an evidence-based intervention to address eye injuries among Florida's migrant citrus harvesters. Participant-observer techniques, other direct observations, and individual and focus group interviews provided data that guided refinement of a safety eyewear intervention. Workers were attracted to the eyewear's ability to minimize irritation, offer protection from trauma, and enable work without declines in productivity or comfort. Access to safety glasses equipped with worker-designed features reduced the perceived barriers of using them; deployment of trained peer-leaders helped promote adoption. Workers' use of safety glasses increased from less than 2% to between 28% and 37% in less than two full harvesting seasons. The combination of formative research and program implementation data provided insights for tailoring an existing evidence-based program for this occupational community and increase potential for future dissemination and worker protection.

Direct observation of atomic-scale origins of local dissolution in Al-Cu-Mg alloys

PubMed Central

Zhang, B.; Wang, J.; Wu, B.; Oguzie, E. E.; Luo, K.; Ma, X. L.

2016-01-01

Atomistic chemical inhomogeneities are anticipated to induce dissimilarities in surface potentials, which control corrosion initiation of alloys at the atomic scale. Precise understanding of corrosion is therefore hampered by lack of definite information describing how atomistic heterogeneities regulate the process. Here, using high-angle annular dark-field (HAADF) scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) techniques, we systematically analyzed the Al20Cu2Mn3 second phase of 2024Al and successfully observed that atomic-scale segregation of Cu at defect sites induced preferential dissolution of the adjacent zones. We define an “atomic-scale galvanic cell”, composed of zones rich in Cu and its surrounding matrix. Our findings provide vital information linking atomic-scale microstructure and pitting mechanism, particularly for Al-Cu-Mg alloys. The resolution achieved also enables understanding of dealloying mechanisms and further streamlines our comprehension of the concept of general corrosion. PMID:28000750

Huygens’ Metasurfaces Enabled by Magnetic Dipole Resonance Tuning in Split Dielectric Nanoresonators

DOE PAGES

Liu, Sheng; Vaskin, Aleksandr; Campione, Salvatore; ...

2017-06-07

Dielectric metasurfaces that exploit the different Mie resonances of nanoscale dielectric resonators are a powerful platform for manipulating electromagnetic fields and can provide novel optical behavior. Here in this work, we experimentally demonstrate independent tuning of the magnetic dipole resonances relative to the electric dipole resonances of split dielectric resonators (SDRs). By increasing the split dimension, we observe a blue shift of the magnetic dipole resonance toward the electric dipole resonance. Therefore, SDRs provide the ability to directly control the interaction between the two dipole resonances within the same resonator. For example, we achieve the first Kerker condition by spectrallymore » overlapping the electric and magnetic dipole resonances and observe significantly suppressed backward scattering. Moreover, we show that a single SDR can be used as an optical nanoantenna that provides strong unidirectional emission from an electric dipole source.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Cheng-Long; Xu, Su-Yang; Belopolski, Ilya

Weyl semimetals provide the realization of Weyl fermions in solid-state physics. Among all the physical phenomena that are enabled by Weyl semimetals, the chiral anomaly is the most unusual one. Here, we report signatures of the chiral anomaly in the magneto-transport measurements on the first Weyl semimetal TaAs. We show negative magnetoresistance under parallel electric and magnetic fields, that is, unlike most metals whose resistivity increases under an external magnetic field, we observe that our high mobility TaAs samples become more conductive as a magnetic field is applied along the direction of the current for certain ranges of the fieldmore » strength. We present systematically detailed data and careful analyses, which allow us to exclude other possible origins of the observed negative magnetoresistance. Finally, our transport data, corroborated by photoemission measurements, first-principles calculations and theoretical analyses, collectively demonstrate signatures of the Weyl fermion chiral anomaly in the magneto-transport of TaAs.« less

Blue straggler stars: lessons from open clusters.

NASA Astrophysics Data System (ADS)

Geller, Aaron M.

Open clusters enable a deep dive into blue straggler characteristics. Recent work shows that the binary properties (frequency, orbital elements and companion masses and evolutionary states) of the blue stragglers are the most important diagnostic for determining their origins. To date the multi-epoch radial-velocity observations necessary for characterizing these blue straggler binaries have only been carried out in open clusters. In this paper, I highlight recent results in the open clusters NGC 188, NGC 2682 (M67) and NGC 6819. The characteristics of many of the blue stragglers in these open clusters point directly to origins through mass transfer from an evolved donor star. Additionally, a handful of blue stragglers show clear signatures of past dynamical encounters. These comprehensive, diverse and detailed observations also reveal important challenges for blue straggler formation models (and particularly the mass-transfer channel), which we must overcome to fully understand the origins of blue straggler stars and other mass-transfer products.

The Galactic Center View with Simbol-X

NASA Astrophysics Data System (ADS)

Raimondi, L.; Malaguti, G.; Angelini, L.; Cappi, M.; Grandi, P.; Palumbo, G. G. C.; Puccetti, S.

2009-05-01

The nature of the hard X-ray emission above 3 keV of the Galactic Centre (GC) is still source of controversy. Recent observations with Chandra are consistent with either a population of discrete sources or with a diffuse non thermal emission or, most likely, a combination of the two. The Simbol-X mission will be equipped with a grazing incident telescope imaging up to ~80 keV, providing an improvement of three orders of magnitude in sensitivity and angular resolution compared with the instruments that have operated so far above 10 keV. This capability will enable to directly disentangle between the discrete source versus the diffuse emission scenarios. This is demonstrated by the Simbol-X simulations of the GC shown here, where the input model includes a list of both diffuse and point sources (both resolved and unresolved) using the input spectrum observed with presently operating X-ray telescopes.

Microbial diversity arising from thermodynamic constraints

PubMed Central

Großkopf, Tobias; Soyer, Orkun S

2016-01-01

The microbial world displays an immense taxonomic diversity. This diversity is manifested also in a multitude of metabolic pathways that can utilise different substrates and produce different products. Here, we propose that these observations directly link to thermodynamic constraints that inherently arise from the metabolic basis of microbial growth. We show that thermodynamic constraints can enable coexistence of microbes that utilise the same substrate but produce different end products. We find that this thermodynamics-driven emergence of diversity is most relevant for metabolic conversions with low free energy as seen for example under anaerobic conditions, where population dynamics is governed by thermodynamic effects rather than kinetic factors such as substrate uptake rates. These findings provide a general understanding of the microbial diversity based on the first principles of thermodynamics. As such they provide a thermodynamics-based framework for explaining the observed microbial diversity in different natural and synthetic environments. PMID:27035705

Wave-Particle Energy Exchange Directly Observed in a Kinetic Alfven-Branch Wave

NASA Technical Reports Server (NTRS)

Gershman, Daniel J.; F-Vinas, Adolfo; Dorelli, John C.; Boardsen, Scott A. (Inventor); Avanov, Levon A.; Bellan, Paul M.; Schwartz, Steven J.; Lavraud, Benoit; Coffey, Victoria N.; Chandler, Michael O.;

Modelling high-resolution ALMA observations of strongly lensed highly star-forming galaxies detected by Herschel

NASA Astrophysics Data System (ADS)

Dye, S.; Furlanetto, C.; Dunne, L.; Eales, S. A.; Negrello, M.; Nayyeri, H.; van der Werf, P. P.; Serjeant, S.; Farrah, D.; Michałowski, M. J.; Baes, M.; Marchetti, L.; Cooray, A.; Riechers, D. A.; Amvrosiadis, A.

2018-06-01

We have modelled ˜0.1 arcsec resolution Atacama Large Millimetre/submillimeter Array imaging of six strong gravitationally lensed galaxies detected by the Herschel Space Observatory. Our modelling recovers mass properties of the lensing galaxies and, by determining magnification factors, intrinsic properties of the lensed submillimetre sources. We find that the lensed galaxies all have high ratios of star formation rate to dust mass, consistent with or higher than the mean ratio for high-redshift submillimetre galaxies and low-redshift ultra-luminous infrared galaxies. Source reconstruction reveals that most galaxies exhibit disturbed morphologies. Both the cleaned image plane data and the directly observed interferometric visibilities have been modelled, enabling comparison of both approaches. In the majority of cases, the recovered lens models are consistent between methods, all six having mass density profiles that are close to isothermal. However, one system with poor signal to noise shows mildly significant differences.

General Astrophysics with the HabEx Workhorse Camera

NASA Astrophysics Data System (ADS)

Stern, Daniel; Clarke, John; Gaudi, B. Scott; Kiessling, Alina; Krause, Oliver; Martin, Stefan; Scowen, Paul; Somerville, Rachel; HabEx STDT

2018-01-01

The Habitable Exoplanet Imaging Mission (HabEx) concept has been designed to enable an extensive suite of science, broadly put under the rubric of General Astrophysics, in addition to its exoplanet direct imaging science. General astrophysics directly addresses multiple NASA programmatic branches, and HabEx will enable investigations ranging from cosmology, to galaxy evolution, to stellar population studies, to exoplanet transit spectroscopy, to Solar System studies. This poster briefly describes one of the two primary HabEx General Astrophysics instruments, the HabEx Workhorse Camera (HWC). HWC will be a dual-detector UV-to-near-IR imager and multi-object grism spectrometer with a microshutter array and a moderate (3' x 3') field-of-view. We detail some of the key science we expect HWC to undertake, emphasizing unique capabilities enabled by a large-aperture, highly stable space-borne platform at these wavelengths.

Two-photon direct frequency comb spectroscopy of alkali atoms

NASA Astrophysics Data System (ADS)

Palm, Christopher; Pradhananga, Trinity; Nguyen, Khoa; Montcrieffe, Caitlin; Kimball, Derek

2012-11-01

We have studied transition frequencies and excited state hyperfine structure in rubidium using 2-photon transitions excited directly with the frequency-doubled output of a erbium fiber optical frequency comb. The frequency comb output is directed in two counterpropagating directions through a vapor cell containing the rubidium vapor. A pair of optical filters is used to select teeth of the comb in order to identify the transition wavelengths. A photomultiplier tube (PMT) measures fluorescence from a decay channel wavelength selected with another optical filter. Using different combinations of filters enables a wide range of transitions to be investigated. By scanning the repetition rate, a Doppler-free spectrum can be obtained enabling kHz-resolution spectral measurements. An interesting dependence of the 2-photon spectrum on the energy of the intermediate state of the 2-photon transition is discussed. Our investigations are laying the groundwork for a long-term research program to use direct frequency comb spectroscopy to understand the complex spectra of rare-earth atoms.

Bioelectrochemical systems-driven directional ion transport enables low-energy water desalination, pollutant removal, and resource recovery.

PubMed

Chen, Xi; Liang, Peng; Zhang, Xiaoyuan; Huang, Xia

2016-09-01

Bioelectrochemical systems (BESs) are integrated water treatment technologies that generate electricity using organic matter in wastewater. In situ use of bioelectricity can direct the migration of ionic substances in a BES, thereby enabling water desalination, resource recovery, and valuable substance production. Recently, much attention has been placed on the microbial desalination cells in BESs to drive water desalination, and various configurations have optimized electricity generation and desalination performance and also coupled hydrogen production, heavy metal reduction, and other reactions. In addition, directional transport of other types of charged ions can remediate polluted groundwater, recover nutrient, and produce valuable substances. To better promote the practical application, the use of BESs as directional drivers of ionic substances requires further optimization to improve energy use efficiency and treatment efficacy. This article reviews existing researches on BES-driven directional ion transport to treat wastewater and identifies a few key factors involved in efficiency optimization. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simultaneous Position, Velocity, Attitude, Angular Rates, and Surface Parameter Estimation Using Astrometric and Photometric Observations

DTIC Science & Technology

2013-07-01

Additionally, a physically consistent BRDF and radiation pressure model is utilized thus enabling an accurate physical link between the observed... BRDF and radiation pressure model is utilized thus enabling an accurate physical link between the observed photometric brightness and the attitudinal...source and the observer is ( ) VLVLH ˆˆˆˆˆ ++= (2) with angles α and β from N̂ and is used in many analytic BRDF models . There are many

Charge Transfer Directed Radical Substitution Enables para-Selective C–H Functionalization

PubMed Central

Boursalian, Gregory B.; Ham, Won Seok; Mazzotti, Anthony R.; Ritter, Tobias

2016-01-01

Efficient C–H functionalization requires selectivity for specific C–H bonds. Progress has been made for directed aromatic substitution reactions to achieve ortho- and meta- selectivity, but a general strategy for para-selective C–H functionalization has remained elusive. Herein, we introduce a previously unappreciated concept which enables nearly complete para selectivity. We propose that radicals with high electron affinity elicit areneto-radical charge transfer in the transition state of radical addition, which is the factor primarily responsible for high positional selectivity. We demonstrate that the selectivity is predictable by a simple theoretical tool and show the utility of the concept through a direct synthesis of aryl piperazines. Our results contradict the notion, widely held by organic chemists, that radical aromatic substitution reactions are inherently unselective. The concept of charge transfer directed radical substitution could serve as the basis for the development of new, highly selective C–H functionalization reactions. PMID:27442288

Advanced Direct-Drive Generator for Improved Availability of Oscillating Wave Surge Converter Power Generation Systems Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Englebretson, Steven; Ouyang, Wen; Tschida, Colin

This report summarizes the activities conducted under the DOE-EERE funded project DE-EE0006400, where ABB Inc. (ABB), in collaboration with Texas A&M’s Advanced Electric Machines & Power Electronics (EMPE) Lab and Resolute Marine Energy (RME) designed, derisked, developed, and demonstrated a novel magnetically geared electrical generator for direct-drive, low-speed, high torque MHK applications The project objective was to investigate a novel and compact direct-drive electric generator and its system aspects that would enable elimination of hydraulic components in the Power Take-Off (PTO) of a Marine and Hydrokinetic (MHK) system with an oscillating wave surge converter (OWSC), thereby improving the availability ofmore » the MHK system. The scope of this project was limited to the development and dry lab demonstration of a low speed generator to enable future direct drive MHK systems.« less

Enabling complex nanoscale pattern customization using directed self-assembly.

PubMed

Doerk, Gregory S; Cheng, Joy Y; Singh, Gurpreet; Rettner, Charles T; Pitera, Jed W; Balakrishnan, Srinivasan; Arellano, Noel; Sanders, Daniel P

2014-12-16

Block copolymer directed self-assembly is an attractive method to fabricate highly uniform nanoscale features for various technological applications, but the dense periodicity of block copolymer features limits the complexity of the resulting patterns and their potential utility. Therefore, customizability of nanoscale patterns has been a long-standing goal for using directed self-assembly in device fabrication. Here we show that a hybrid organic/inorganic chemical pattern serves as a guiding pattern for self-assembly as well as a self-aligned mask for pattern customization through cotransfer of aligned block copolymer features and an inorganic prepattern. As informed by a phenomenological model, deliberate process engineering is implemented to maintain global alignment of block copolymer features over arbitrarily shaped, 'masking' features incorporated into the chemical patterns. These hybrid chemical patterns with embedded customization information enable deterministic, complex two-dimensional nanoscale pattern customization through directed self-assembly.

Charge-transfer-directed radical substitution enables para-selective C-H functionalization

NASA Astrophysics Data System (ADS)

Boursalian, Gregory B.; Ham, Won Seok; Mazzotti, Anthony R.; Ritter, Tobias

2016-08-01

Efficient C-H functionalization requires selectivity for specific C-H bonds. Progress has been made for directed aromatic substitution reactions to achieve ortho and meta selectivity, but a general strategy for para-selective C-H functionalization has remained elusive. Herein we introduce a previously unappreciated concept that enables nearly complete para selectivity. We propose that radicals with high electron affinity elicit arene-to-radical charge transfer in the transition state of radical addition, which is the factor primarily responsible for high positional selectivity. We demonstrate with a simple theoretical tool that the selectivity is predictable and show the utility of the concept through a direct synthesis of aryl piperazines. Our results contradict the notion, widely held by organic chemists, that radical aromatic substitution reactions are inherently unselective. The concept of radical substitution directed by charge transfer could serve as the basis for the development of new, highly selective C-H functionalization reactions.

Design Dimensions Enabling Divergent Behaviour across Physical, Digital, and Social Library Interfaces

NASA Astrophysics Data System (ADS)

Björneborn, Lennart

What design dimensions across physical, digital, and social library interfaces may enable and trigger users to find more information resources than planned or known in advance? The paper outlines a conceptual framework with libraries as integrative interfaces across physical, digital, and social affordances and users that mix convergent (goal-directed) and divergent (exploratory) information behaviour. Ten design dimensions that enable and trigger divergent behaviour are outlined. Implications for persuasive design are discussed.

Effect of Binding Components in Complex Sample Matrices on Recovery in Direct Immersion Solid-Phase Microextraction: Friends or Foe?

PubMed

Alam, Md Nazmul; Pawliszyn, Janusz

2018-02-20

The development of matrix compatible coatings for solid-phase microextraction (SPME) has enabled direct extraction of analytes from complex sample matrices. The direct immersion (DI) mode of SPME when utilized in conjunction with such extraction phases facilitates extraction of a wide range of analytes from complex matrices without the incurrence of fouling or coating saturation. In this work, mathematical models and computational simulations were employed to investigate the effect of binding components present in complex samples on the recovery of small molecules varying in logP for extractions carried out using the direct immersion approach. The presented findings corroborate that the studied approach indeed enables the extraction of both polar and nonpolar analytes from complex matrices, provided a suitable sorbent is employed. Further results indicated that, in certain cases, the kinetics of extraction of a given analyte in its free form might be dependent on the desorption kinetics of their bound form from matrix components, which might lower total recoveries of analytes with high affinity for the matrix. However, the binding of analytes to matrix components also enables SPME to extract a balanced quantity of different logP analytes, facilitated by multiphase equilibria, with a single extraction device.

New Mission to Measure Global Lightning from the International Space Station (ISS)

NASA Astrophysics Data System (ADS)

Blakeslee, R. J.; Christian, H. J., Jr.; Mach, D. M.; Buechler, D. E.; Koshak, W. J.; Walker, T. D.; Bateman, M. G.; Stewart, M. F.; O'Brien, S.; Wilson, T. O.; Pavelitz, S. D.; Coker, C.

2015-12-01

Over the past 20 years, the NASA Marshall Space Flight Center, the University of Alabama in Huntsville, and their partners developed and demonstrated the effectiveness and value of space-based lightning observations as a remote sensing tool for Earth science research and applications, and, in the process, established a robust global lightning climatology. The observations included measurements from the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) that acquired global observations of total lightning (i.e., intracloud and cloud-to-ground discharges) from November 1997 to April 2015 between 38° N/S latitudes, and its Optical Transient Detector predecessor that acquired observation from May 1995 to April 2000 over 75° N/S latitudes. In February 2016, as an exciting follow-on to these prior missions, a space-qualified LIS built as a flight-spare for TRMM will be delivered to the International Space Station (ISS) for a 2 year or longer mission, flown as a hosted payload on the Department of Defense Space Test Program-Houston 5 (STP-H5) mission. The LIS on ISS will continue observations of the amount, rate, and radiant energy of total lightning over the Earth. More specifically, LIS measures lightning during both day and night, with storm scale resolution (~4 km), millisecond timing, and high, uniform detection efficiency, without any land-ocean bias. Lightning is a direct and most impressive response to intense atmospheric convection. ISS LIS lightning observations will continue to provide important gap-filling inputs to pressing Earth system science issues across a broad range of disciplines. This mission will also extend TRMM time series observations, expand the latitudinal coverage to 54° latitude, provide real-time lightning data to operational users, espically over data sparse oceanic regions, and enable cross-sensor observations and calibrations that includes the new GOES-R Geostationary Lightning Mapper (GLM) and the Meteosat Third Generation Lightning Imager (MTG LI). The ISS platform will also uniquely enable LIS to provide simultaneous and complementary observations with other ISS payloads such as the European Space Agency's Atmosphere-Space Interaction Monitor (ASIM) exploring the connection between lightning and terrestrial gamma-ray flashes (TGFs).

75 FR 10194 - Direct Single Family Housing Loans and Grants

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-05

... Part 3550 RIN 0575-AC81 Direct Single Family Housing Loans and Grants AGENCY: Rural Housing Service... to amend its regulations for the Direct Single Family Housing Loans by reinstating language to enable... via the U.S. Postal Service to the Branch Chief, Regulations and Paperwork Management Branch, U.S...

Two-photon Direct Frequency Comb Spectroscopy of Alkali Atoms

NASA Astrophysics Data System (ADS)

Nguyen, Khoa; Pradhananga, Trinity; Palm, Christopher; Stalnaker, Jason; Kimball, Derek Jackson

2012-06-01

We are using direct frequency comb spectroscopy to study transition frequencies and excited state hyperfine structure in potassium and rubidium using 2-photon transitions excited directly with the frequency-doubled output of a erbium fiber optical frequency comb. The frequency comb output is directed in two counterpropagating directions through a vapor cell containing the atomic vapor of interest. A pair of optical filters is used to select teeth of the comb in order to identify the transition wavelengths. A photomultiplier tube (PMT) measures fluorescence from a decay channel wavelength selected with another optical filter. Using different combinations of filters enables a wide range of transitions to be investigated. By scanning the repetition rate, a Doppler-free spectrum can be obtained enabling kHz-resolution spectral measurements. The thermal motion of the atoms in the vapor cell actually eliminates the need to fine-tune the offset frequency and repetition rate, alleviating a somewhat challenging requirement for spectroscopy of cold atoms. Our investigations are laying the groundwork for a long-term research program to use direct frequency comb spectroscopy to understand the complex spectra of rare-earth atoms.

Direct Frequency Comb Spectroscopy of Alkali Atoms

NASA Astrophysics Data System (ADS)

Pradhananga, Trinity; Palm, Christopher; Nguyen, Khoa; Guttikonda, Srikanth; Kimball, Derek Jackson

2011-11-01

We are using direct frequency comb spectroscopy to study transition frequencies and excited state hyperfine structure in potassium and rubidium using 2-photon transitions excited directly with the frequency-doubled output of a erbium fiber optical frequency comb. The frequency comb output is directed in two counterpropagating directions through a vapor cell containing the atomic vapor of interest. A pair of optical filters is used to select teeth of the comb in order to identify the transition wavelengths. A photomultiplier tube (PMT) measures fluorescence from a decay channel wavelength selected with another optical filter. Using different combinations of filters enables a wide range of transitions to be investigated. By scanning the repetition rate, a Doppler-free spectrum can be obtained enabling kHz-resolution spectral measurements. The thermal motion of the atoms in the vapor cell actually eliminates the need to fine-tune the offset frequency and repetition rate, alleviating a somewhat challenging requirement for spectroscopy of cold atoms. Our investigations are laying the groundwork for a long-term research program to use direct frequency comb spectroscopy to understand the complex spectra of rare-earth atoms.

Reconciling the Dawn-Dusk Asymmetry in Mercury’s Exosphere with the Micrometeoroid Impact Directionality

NASA Astrophysics Data System (ADS)

Pokorný, Petr; Sarantos, Menelaos; Janches, Diego

2017-06-01

Combining dynamical models of dust from Jupiter-family comets and Halley-type comets, we demonstrate that the seasonal variation of the dust/meteoroid environment at Mercury is responsible for producing the dawn-dusk asymmetry in Mercury’s exosphere observed by the MESSENGER spacecraft. Our latest models, calibrated recently from ground-based and space-borne measurements, provide unprecedented statistics that enable us to study the longitudinal and latitudinal distribution of meteoroids impacting Mercury’s surface. We predict that the micrometeoroid impact vaporization source is expected to undergo significant motion on Mercury’s surface toward the nightside during Mercury’s approach to aphelion and toward the dayside when the planet is approaching the Sun.

The Challenges of Low-Frequency Radio Polarimetry: Lessons from the Murchison Widefield Array

NASA Astrophysics Data System (ADS)

Lenc, E.; Anderson, C. S.; Barry, N.; Bowman, J. D.; Cairns, I. H.; Farnes, J. S.; Gaensler, B. M.; Heald, G.; Johnston-Hollitt, M.; Kaplan, D. L.; Lynch, C. R.; McCauley, P. I.; Mitchell, D. A.; Morgan, J.; Morales, M. F.; Murphy, Tara; Offringa, A. R.; Ord, S. M.; Pindor, B.; Riseley, C.; Sadler, E. M.; Sobey, C.; Sokolowski, M.; Sullivan, I. S.; O'Sullivan, S. P.; Sun, X. H.; Tremblay, S. E.; Trott, C. M.; Wayth, R. B.

2017-09-01

We present techniques developed to calibrate and correct Murchison Widefield Array low-frequency (72-300 MHz) radio observations for polarimetry. The extremely wide field-of-view, excellent instantaneous (u, v)-coverage and sensitivity to degree-scale structure that the Murchison Widefield Array provides enable instrumental calibration, removal of instrumental artefacts, and correction for ionospheric Faraday rotation through imaging techniques. With the demonstrated polarimetric capabilities of the Murchison Widefield Array, we discuss future directions for polarimetric science at low frequencies to answer outstanding questions relating to polarised source counts, source depolarisation, pulsar science, low-mass stars, exoplanets, the nature of the interstellar and intergalactic media, and the solar environment.

Traffic Monitor

NASA Technical Reports Server (NTRS)

1995-01-01

Intelligent Vision Systems, Inc. (InVision) needed image acquisition technology that was reliable in bad weather for its TDS-200 Traffic Detection System. InVision researchers used information from NASA Tech Briefs and assistance from Johnson Space Center to finish the system. The NASA technology used was developed for Earth-observing imaging satellites: charge coupled devices, in which silicon chips convert light directly into electronic or digital images. The TDS-200 consists of sensors mounted above traffic on poles or span wires, enabling two sensors to view an intersection; a "swing and sway" feature to compensate for movement of the sensors; a combination of electronic shutter and gain control; and sensor output to an image digital signal processor, still frame video and optionally live video.

Reconciling the Dawn-Dusk Asymmetry in Mercury's Exosphere with the Micrometeoroid Impact Directionality

NASA Technical Reports Server (NTRS)

Pokorny, Petr; Sarantos, Menelaos; Janches, Diego

2017-01-01

Combining dynamical models of dust from Jupiter-family comets and Halley-type comets, we demonstrate that the seasonal variation of the dust/meteoroid environment at Mercury is responsible for producing the dawn-dusk asymmetry in Mercury's exosphere observed by the MESSENGER spacecraft. Our latest models, calibrated recently from ground-based and space-borne measurements, provide unprecedented statistics that enable us to study the longitudinal and latitudinal distribution of meteoroids impacting Mercury's surface. We predict that the micrometeoroid impact vaporization source is expected to undergo significant motion on Mercury's surface toward the nightside during Mercury's approach to aphelion and toward the dayside when the planet is approaching the Sun.

Black GE based on crystalline/amorphous core/shell nanoneedle arrays

DOEpatents

Javey, Ali; Chueh, Yu-Lun; Fan, Zhiyong

2014-03-04

Direct growth of black Ge on low-temperature substrates, including plastics and rubber is reported. The material is based on highly dense, crystalline/amorphous core/shell Ge nanoneedle arrays with ultrasharp tips (.about.4 nm) enabled by the Ni catalyzed vapor-solid-solid growth process. Ge nanoneedle arrays exhibit remarkable optical properties. Specifically, minimal optical reflectance (<1%) is observed, even for high angles of incidence (.about.75.degree.) and for relatively short nanoneedle lengths (.about.1 .mu.m). Furthermore, the material exhibits high optical absorption efficiency with an effective band gap of .about.1 eV. The reported black Ge can have important practical implications for efficient photovoltaic and photodetector applications on nonconventional substrates.

Acid-base chemistry of frustrated water at protein interfaces.

PubMed

Fernández, Ariel

2016-01-01

Water molecules at a protein interface are often frustrated in hydrogen-bonding opportunities due to subnanoscale confinement. As shown, this condition makes them behave as a general base that may titrate side-chain ammonium and guanidinium cations. Frustration-based chemistry is captured by a quantum mechanical treatment of proton transference and shown to remove same-charge uncompensated anticontacts at the interface found in the crystallographic record and in other spectroscopic information on the aqueous interface. Such observations are untenable within classical arguments, as hydronium is a stronger acid than ammonium or guanidinium. Frustration enables a directed Grotthuss mechanism for proton transference stabilizing same-charge anticontacts. © 2015 Federation of European Biochemical Societies.

Impairment of prosocial sentiments is associated with frontopolar and septal damage in frontotemporal dementia.

PubMed

Moll, Jorge; Zahn, Roland; de Oliveira-Souza, Ricardo; Bramati, Ivanei E; Krueger, Frank; Tura, Bernardo; Cavanagh, Alyson L; Grafman, Jordan

2011-01-15

Poets and philosophers have long acknowledged moral sentiments as key motivators of human social behavior. Prosocial sentiments, which include guilt, pity and embarrassment, enable us to care about others and to be concerned about our mistakes. Functional imaging studies have implicated frontopolar, ventromedial frontal and basal forebrain regions in the experience of prosocial sentiments. Patients with lesions of the frontopolar and ventromedial frontal areas were observed to behave inappropriately and less prosocially, which could be attributed to a generalized emotional blunting. Direct experimental evidence for brain regions distinctively associated with moral sentiment impairments is lacking, however. We investigated this issue in patients with the behavioral variant of frontotemporal dementia, a disorder in which early and selective impairments of social conduct are consistently observed. Using a novel moral sentiment task, we show that the degree of impairment of prosocial sentiments is associated with the degree of damage to frontopolar cortex and septal area, as assessed with 18-Fluoro-Deoxy-Glucose-Positron Emission Tomography, an established measure of neurodegenerative damage. This effect was dissociable from impairment of other-critical feelings (anger and disgust), which was in turn associated with dorsomedial prefrontal and amygdala dysfunction. Our findings suggest a critical role of the frontopolar cortex and septal region in enabling prosocial sentiments, a fundamental component of moral conscience. Published by Elsevier Inc.

Dendrites and Pits: Untangling the Complex Behavior of Lithium Metal Anodes through Operando Video Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, Kevin N.; Kazyak, Eric; Chadwick, Alexander F.

Enabling ultra-high energy density rechargeable Li batteries would have widespread impact on society. But, the critical challenges of Li metal anodes (most notably cycle life and safety) remain unsolved. This is attributed to the evolution of Li metal morphology during cycling, which leads to dendrite growth and surface pitting. Herein, we present a comprehensive understanding of the voltage variations observed during Li metal cycling, which is directly correlated to morphology evolution through the use of operando video microscopy. A custom-designed visualization cell was developed to enable operando synchronized observation of Li metal electrode morphology and electrochemical behavior during cycling. Amore » mechanistic understanding of the complex behavior of these electrodes is gained through correlation with continuum-scale modeling, which provides insight into the dominant surface kinetics. Our work provides a detailed explanation of (1) when dendrite nucleation occurs, (2) how those dendrites evolve as a function of time, (3) when surface pitting occurs during Li electrodissolution, (4) kinetic parameters that dictate overpotential as the electrode morphology evolves, and (5) how this understanding can be applied to evaluate electrode performance in a variety of electrolytes. Our results provide detailed insight into the interplay between morphology and the dominant electrochemical processes occurring on the Li electrode surface through an improved understanding of changes in cell voltage, which represents a powerful new platform for analysis.« less

Dendrites and Pits: Untangling the Complex Behavior of Lithium Metal Anodes through Operando Video Microscopy

DOE PAGES

Wood, Kevin N.; Kazyak, Eric; Chadwick, Alexander F.; ...

2015-10-14

Enabling ultra-high energy density rechargeable Li batteries would have widespread impact on society. But, the critical challenges of Li metal anodes (most notably cycle life and safety) remain unsolved. This is attributed to the evolution of Li metal morphology during cycling, which leads to dendrite growth and surface pitting. Herein, we present a comprehensive understanding of the voltage variations observed during Li metal cycling, which is directly correlated to morphology evolution through the use of operando video microscopy. A custom-designed visualization cell was developed to enable operando synchronized observation of Li metal electrode morphology and electrochemical behavior during cycling. Amore » mechanistic understanding of the complex behavior of these electrodes is gained through correlation with continuum-scale modeling, which provides insight into the dominant surface kinetics. Our work provides a detailed explanation of (1) when dendrite nucleation occurs, (2) how those dendrites evolve as a function of time, (3) when surface pitting occurs during Li electrodissolution, (4) kinetic parameters that dictate overpotential as the electrode morphology evolves, and (5) how this understanding can be applied to evaluate electrode performance in a variety of electrolytes. Our results provide detailed insight into the interplay between morphology and the dominant electrochemical processes occurring on the Li electrode surface through an improved understanding of changes in cell voltage, which represents a powerful new platform for analysis.« less

Migration of magnetotactic bacteria in porous media.

PubMed

Rismani Yazi, Saeed; Nosrati, Reza; Stevens, Corey A; Vogel, David; Escobedo, Carlos

2018-01-01

Magnetotactic bacteria (MTB) migrate in complex porous sediments where fluid flow is ubiquitous. Here, we demonstrate that magnetotaxis enables MTB to migrate effectively through porous micromodels. Directed MTB can circumvent curved obstacles by traveling along the boundaries and pass flat obstacles by repeatedly switching between forward and backward runs. Magnetotaxis enables directed motion of MTB through heterogeneous porous media, overcoming tortuous flow fields with local velocities as high as 250  μ m s -1 . Our findings bring new insights into the migration behaviour of MTB in their natural habitats and their potential in vivo applications as microbiorobots.

Stereospecific Palladium-Catalyzed C-H Arylation of Pyroglutamic Acid Derivatives at the C3 Position Enabled by 8-Aminoquinoline as a Directing Group.

PubMed

Verho, Oscar; Maetani, Micah; Melillo, Bruno; Zoller, Jochen; Schreiber, Stuart L

2017-09-01

An efficient and stereospecific Pd-catalyzed protocol for the C-H arylation of pyroglutamic acid derivatives that uses 8-aminoquinoline as a directing group is described. The reaction was shown to proceed efficiently with a variety of aryl and heteroaryl iodides bearing different functional groups, giving C3-arylated cis products in good to high yields. Removal of the 8-aminoquinoline unit from these C-H arylation products enables access to synthetically useful cis and trans pyroglutamic acid-based building blocks.

Direct atomic fabrication and dopant positioning in Si using electron beams with active real-time image-based feedback.

PubMed

Jesse, Stephen; Hudak, Bethany M; Zarkadoula, Eva; Song, Jiaming; Maksov, Artem; Fuentes-Cabrera, Miguel; Ganesh, Panchapakesan; Kravchenko, Ivan; Snijders, Panchapakesan C; Lupini, Andrew R; Borisevich, Albina Y; Kalinin, Sergei V

2018-06-22

Semiconductor fabrication is a mainstay of modern civilization, enabling the myriad applications and technologies that underpin everyday life. However, while sub-10 nanometer devices are already entering the mainstream, the end of the Moore's law roadmap still lacks tools capable of bulk semiconductor fabrication on sub-nanometer and atomic levels, with probe-based manipulation being explored as the only known pathway. Here we demonstrate that the atomic-sized focused beam of a scanning transmission electron microscope can be used to manipulate semiconductors such as Si on the atomic level, inducing growth of crystalline Si from the amorphous phase, reentrant amorphization, milling, and dopant front motion. These phenomena are visualized in real-time with atomic resolution. We further implement active feedback control based on real-time image analytics to automatically control the e-beam motion, enabling shape control and providing a pathway for atom-by-atom correction of fabricated structures in the near future. These observations open a new epoch for atom-by-atom manufacturing in bulk, the long-held dream of nanotechnology.

Optical Communication on SmallSats - Enabling the Next Era in Space Science (a Keck Institute for Space Studies Workshop)

NASA Astrophysics Data System (ADS)

Grefenstette, Brian

2017-08-01

Small satellites (<50 kg) have revolutionized the possibilities for inexpensive science from space-borne platforms. A number of scientific CubeSats have been recently launched or are under development, including some bound for interplanetary space. Recent miniaturization of technology for high-precision pointing, high efficiency solar power, high-powered on-board processing, and scientific detectors provide the capability for groundbreaking, focused science from these resource-limited spacecraft. Similar innovations in both radio frequency and optical/laser communications are poised to increase telemetry bandwidth to a gigabit per second (Gb/s) or more. This enhancement can allow real-time, global science measurements and/or ultra-high fidelity (resolution, cadence, etc.) observations from tens or hundreds of Earth-orbiting satellites, or permit high-bandwidth, direct-to-earth communications for (inter)planetary missions. Here we present the results of a recent Keck Institue for Space Science workshop that brought together scientists and engineers from academia and industry to showcase the breakthrough science enabled by optical communications on small satellites for future missions.

Direct atomic fabrication and dopant positioning in Si using electron beams with active real-time image-based feedback

NASA Astrophysics Data System (ADS)

Jesse, Stephen; Hudak, Bethany M.; Zarkadoula, Eva; Song, Jiaming; Maksov, Artem; Fuentes-Cabrera, Miguel; Ganesh, Panchapakesan; Kravchenko, Ivan; Snijders, Panchapakesan C.; Lupini, Andrew R.; Borisevich, Albina Y.; Kalinin, Sergei V.

2018-06-01

Semiconductor fabrication is a mainstay of modern civilization, enabling the myriad applications and technologies that underpin everyday life. However, while sub-10 nanometer devices are already entering the mainstream, the end of the Moore’s law roadmap still lacks tools capable of bulk semiconductor fabrication on sub-nanometer and atomic levels, with probe-based manipulation being explored as the only known pathway. Here we demonstrate that the atomic-sized focused beam of a scanning transmission electron microscope can be used to manipulate semiconductors such as Si on the atomic level, inducing growth of crystalline Si from the amorphous phase, reentrant amorphization, milling, and dopant front motion. These phenomena are visualized in real-time with atomic resolution. We further implement active feedback control based on real-time image analytics to automatically control the e-beam motion, enabling shape control and providing a pathway for atom-by-atom correction of fabricated structures in the near future. These observations open a new epoch for atom-by-atom manufacturing in bulk, the long-held dream of nanotechnology.

a Low-Cost and Lightweight 3d Interactive Real Estate-Purposed Indoor Virtual Reality Application

NASA Astrophysics Data System (ADS)

Ozacar, K.; Ortakci, Y.; Kahraman, I.; Durgut, R.; Karas, I. R.

2017-11-01

Interactive 3D architectural indoor design have been more popular after it benefited from Virtual Reality (VR) technologies. VR brings computer-generated 3D content to real life scale and enable users to observe immersive indoor environments so that users can directly modify it. This opportunity enables buyers to purchase a property off-the-plan cheaper through virtual models. Instead of showing property through 2D plan or renders, this visualized interior architecture of an on-sale unbuilt property is demonstrated beforehand so that the investors have an impression as if they were in the physical building. However, current applications either use highly resource consuming software, or are non-interactive, or requires specialist to create such environments. In this study, we have created a real-estate purposed low-cost high quality fully interactive VR application that provides a realistic interior architecture of the property by using free and lightweight software: Sweet Home 3D and Unity. A preliminary study showed that participants generally liked proposed real estate-purposed VR application, and it satisfied the expectation of the property buyers.

Company Profile: Selventa, Inc.

PubMed

Fryburg, David A; Latino, Louis J; Tagliamonte, John; Kenney, Renee D; Song, Diane H; Levine, Arnold J; de Graaf, David

2012-08-01

Selventa, Inc. (MA, USA) is a biomarker discovery company that enables personalized healthcare. Originally founded as Genstruct, Inc., Selventa has undergone significant evolution from a technology-based service provider to an active partner in the development of diagnostic tests, functioning as a molecular dashboard of disease activity using a unique platform. As part of that evolution, approximately 2 years ago the company was rebranded as Selventa to reflect its new identity and mission. The contributions to biomedical research by Selventa are based on in silico, reverse-engineering methods to determine biological causality. That is, given a set of in vitro or in vivo biological observations, which biological mechanisms can explain the measured results? Facilitated by a large and carefully curated knowledge base, these in silico methods generated new insights into the mechanisms driving a disease. As Selventa's methods would enable biomarker discovery and be directly applicable to generating novel diagnostics, the scientists at Selventa have focused on the development of predictive biomarkers of response in autoimmune and oncologic diseases. Selventa is presently building a portfolio of independent, as well as partnered, biomarker projects with the intention to create diagnostic tests that predict response to therapy.

ARPS Enabled Titan Rover Concept with Inflatable Wheels

NASA Technical Reports Server (NTRS)

Balint, Tibor S.; Schriener, Timothy M.; Shirley, James H.

2006-01-01

The Decadal Survey identified Titan as one of the top priority science destinations in the large moons category, while NASA's proposed Design Reference Mission Set ranked a Titan in-situ explorer second, after a recommended Europa Geophysical Observer mission. This paper discusses a Titan rover concept, enabled by a single advanced Radioisotope Power System that could provide about 110We (BOL). The concept targets the smaller Flagship or potentially the New Frontiers mission class. This MSL class rover would traverse on four 1.5 m diameter inflatable wheels during its 3 years mission duration and would use as much design and flight heritage as possible to reduce mission cost. Direct to Earth communication would remove the need for a relay orbiter. Details on the strawman instrument payload, and rover subsystems are given for this science driven mission concept. In addition, power system trades between Advanced RTG, TPV, and Advanced Stirling and Brayton Radioisotope Power Systems (RPS) are outlined. While many possible approaches exist for Titan in-situ exploration, the Titan rover concept presented here could provide a scientifically interesting and programmatically affordable solution.

Transverse angular momentum in topological photonic crystals

NASA Astrophysics Data System (ADS)

Deng, Wei-Min; Chen, Xiao-Dong; Zhao, Fu-Li; Dong, Jian-Wen

2018-01-01

Engineering local angular momentum of structured light fields in real space enables applications in many fields, in particular, the realization of unidirectional robust transport in topological photonic crystals with a non-trivial Berry vortex in momentum space. Here, we show transverse angular momentum modes in silicon topological photonic crystals when considering transverse electric polarization. Excited by a chiral external source with either transverse spin angular momentum or transverse phase vortex, robust light flow propagating along opposite directions is observed in several kinds of sharp-turn interfaces between two topologically-distinct silicon photonic crystals. A transverse orbital angular momentum mode with alternating phase vortex exists at the boundary of two such photonic crystals. In addition, unidirectional transport is robust to the working frequency even when the ring size or location of the pseudo-spin source varies in a certain range, leading to the superiority of the broadband photonic device. These findings enable one to make use of transverse angular momentum, a kind of degree of freedom, to achieve unidirectional robust transport in the telecom region and other potential applications in integrated photonic circuits, such as on-chip robust delay lines.

Mesoplasticity approach to studies of the cutting mechanism in ultra-precision machining

NASA Astrophysics Data System (ADS)

Lee, Rongbin W. B.; Wang, Hao; To, Suet; Cheung, Chi Fai; Chan, Chang Yuen

2014-03-01

There have been various theoretical attempts by researchers worldwide to link up different scales of plasticity studies from the nano-, micro- and macro-scale of observation, based on molecular dynamics, crystal plasticity and continuum mechanics. Very few attempts, however, have been reported in ultra-precision machining studies. A mesoplasticity approach advocated by Lee and Yang is adopted by the authors and is successfully applied to studies of the micro-cutting mechanisms in ultra-precision machining. Traditionally, the shear angle in metal cutting, as well as the cutting force variation, can only be determined from cutting tests. In the pioneering work of the authors, the use of mesoplasticity theory enables prediction of the fluctuation of the shear angle and micro-cutting force, shear band formation, chip morphology in diamond turning and size effect in nano-indentation. These findings are verified by experiments. The mesoplasticity formulation opens up a new direction of studies to enable how the plastic behaviour of materials and their constitutive representations in deformation processing, such as machining can be predicted, assessed and deduced from the basic properties of the materials measurable at the microscale.

Three-dimensional Super Resolution Microscopy of F-actin Filaments by Interferometric PhotoActivated Localization Microscopy (iPALM).

PubMed

Wang, Yilin; Kanchanawong, Pakorn

2016-12-01

Fluorescence microscopy enables direct visualization of specific biomolecules within cells. However, for conventional fluorescence microscopy, the spatial resolution is restricted by diffraction to ~ 200 nm within the image plane and > 500 nm along the optical axis. As a result, fluorescence microscopy has long been severely limited in the observation of ultrastructural features within cells. The recent development of super resolution microscopy methods has overcome this limitation. In particular, the advent of photoswitchable fluorophores enables localization-based super resolution microscopy, which provides resolving power approaching the molecular-length scale. Here, we describe the application of a three-dimensional super resolution microscopy method based on single-molecule localization microscopy and multiphase interferometry, called interferometric PhotoActivated Localization Microscopy (iPALM). This method provides nearly isotropic resolution on the order of 20 nm in all three dimensions. Protocols for visualizing the filamentous actin cytoskeleton, including specimen preparation and operation of the iPALM instrument, are described here. These protocols are also readily adaptable and instructive for the study of other ultrastructural features in cells.

Star & Planet Formation Studies and Opportunities with SOFIA

NASA Technical Reports Server (NTRS)

Smith, Kimberly Ennico

2018-01-01

Star formation, the most fundamental process in the universe, is linked to planet formation and thus to the origin and evolution of life. We have a general outline of how planets and stars form, yet unraveling the details of the physics and chemistry continues to challenge us. The infrared and submillimeter part of the spectrum hold the most promise for studying the beginnings of star formation. The observational landscape recently shaped by Spitzer, Herschel and ALMA, continues to challenge our current theories. SOFIA, the Stratospheric Observatory for Infrared Astronomy, equipped with state-of-the-art infrared instrumentation to a vantage point at 45,000 feet (13.7 kilometers) flight altitude that is above 99.9 percent of the Earth's water vapor, enables observations in the infrared through terahertz frequencies not possible from the ground. SOFIA is a community observatory, about to start its sixth annual observing cycle. My talk will focus on recent results in advancing star and planet formation processes using SOFIA's imaging and polarimetric capabilities, and the upcoming science enabled by the 3rd generation instrument High-Resolution Mid-Infrared Spectrometer (HIRMES) to be commissioned in 2019. I will show how mid-infrared imaging is used to test massive star formation theories, how far-infrared polarimetry on sub-parsec scales is directly testing the role of magnetic fields in molecular clouds, and how velocity-resolved high-resolution spectroscopy will push forward our understanding of proto-planetary disk science. I will also summarize upcoming opportunities with the SOFIA observatory. For the latest news about your flying observatory, see https://sofia.usra.edu/.

Augmenting WFIRST Microlensing with a Ground-Based Telescope Network

NASA Astrophysics Data System (ADS)

Zhu, Wei; Gould, Andrew

2016-06-01

Augmenting the Wide Field Infrared Survey Telescope (WFIRST) microlensing campaigns with intensive observations from a ground-based network of wide-field survey telescopes would have several major advantages. First, it would enable full two-dimensional (2-D) vector microlens parallax measurements for a substantial fraction of low-mass lenses as well as planetary and binary events that show caustic crossing features. For a significant fraction of the free-floating planet (FFP) events and all caustic-crossing planetary/binary events, these 2-D parallax measurements directly lead to complete solutions (mass, distance, transverse velocity) of the lens object (or lens system). For even more events, the complementary ground-based observations will yield 1-D parallax measurements. Together with the 1-D parallaxes from WFIRST alone, they can probe the entire mass range M > M_Earth. For luminous lenses, such 1-D parallax measurements can be promoted to complete solutions (mass, distance, transverse velocity) by high-resolution imaging. This would provide crucial information not only about the hosts of planets and other lenses, but also enable a much more precise Galactic model. Other benefits of such a survey include improved understanding of binaries (particularly with low mass primaries), and sensitivity to distant ice-giant and gas-giant companions of WFIRST lenses that cannot be detected by WFIRST itself due to its restricted observing windows. Existing ground-based microlensing surveys can be employed if WFIRST is pointed at lower-extinction fields than is currently envisaged. This would come at some cost to the event rate. Therefore the benefits of improved characterization of lenses must be weighed against these costs.

Towards Designing Cognitively-Enriched Project-Oriented Courses within a Blended Problem-Based Learning Context

ERIC Educational Resources Information Center

Tambouris, Efthimios; Zotou, Maria; Tarabanis, Konstantinos

2014-01-01

Traditional education seems to gradually and moderately make way for self-directed and student-centred learning strategies that will efficiently enable students to reach their full potentials and will sufficiently prepare them for their upcoming professional careers. Problem-Based Learning (PBL) is such a strategy, since it enables active…

Disconnects between the enabling legislation and management planning

Treesearch

Christopher Hawkins; David K. Loomis

2007-01-01

The natural resource management paradigm in place for the past century has favored an expert-client approach, whereby managers have used wise biological principles in conjunction with clientele preferences to enable local, regional, and national decision-making. This paradigm, though acceptable when the primary clients were direct resource consumers (e.g., fishermen,...

Brief Report: Just-in-Time Visual Supports to Children with Autism via the Apple Watch:® A Pilot Feasibility Study.

PubMed

O'Brien, Amanda; Schlosser, Ralf W; Shane, Howard C; Abramson, Jennifer; Allen, Anna A; Flynn, Suzanne; Yu, Christina; Dimery, Katherine

2016-12-01

Using augmented input might be an effective means for supplementing spoken language for children with autism who have difficulties following spoken directives. This study aimed to (a) explore whether JIT-delivered scene cues (photos, video clips) via the Apple Watch ® enable children with autism to carry out directives they were unable to implement with speech alone, and (b) test the feasibility of the Apple Watch ® (with a focus on display size). Results indicated that the hierarchical JIT supports enabled five children with autism to carry out the majority of directives. Hence, the relatively small display size of the Apple Watch does not seem to hinder children with autism to glean critical information from visual supports.

Stiffness of RBC optical confinement affected by optical clearing

NASA Astrophysics Data System (ADS)

Grishin, Oleg V.; Fedosov, Ivan V.; Tuchin, Valery V.

2017-03-01

In vivo optical trapping is a novel applied direction of an optical manipulation, which enables one to noninvasive measurement of mechanical properties of cells and tissues in living animals directly. But an application area of this direction is limited because strong scattering of many biological tissues. An optical clearing enables one to decrease the scattering and therefore increase a depth of light penetration, decrease a distortion of light beam, improve a resolution in imaging applications. Now novel methods had appeared for a measurement an optical clearing degree at a cellular level. But these methods aren't applicable in vivo. In this paper we present novel measurement method of estimate of the optical clearing, which are based on a measurement of optical trap stiffness. Our method may be applicable in vivo.

Grippers Based on Opposing Van Der Waals Adhesive Pads

NASA Technical Reports Server (NTRS)

Parness, Aaron (Inventor); Kennedy, Brett A. (Inventor); Heverly, Matthew C (Inventor); Cutkosky, Mark R. (Inventor); Hawkes, Elliot Wright (Inventor)

2016-01-01

Novel gripping structures based on van der Waals adhesive forces are disclosed. Pads covered with fibers can be activated in pairs by opposite forces, thereby enabling control of the adhesive force in an ON or OFF state. Pads can be used in groups, each comprising a group of opposite pads. The adhesive structures enable anchoring forces that can resist adverse forces from different directions. The adhesive structures can be used to enable the operation of robots on surfaces of space vehicles.

Dynamic Receptor Team Formation Can Explain the High Signal Transduction Gain in Escherichia coli

PubMed Central

Albert, Réka; Chiu, Yu-wen; Othmer, Hans G.

2004-01-01

Evolution has provided many organisms with sophisticated sensory systems that enable them to respond to signals in their environment. The response frequently involves alteration in the pattern of movement, either by directed movement, a process called taxis, or by altering the speed or frequency of turning, which is called kinesis. Chemokinesis has been most thoroughly studied in the peritrichous bacterium Escherichia coli, which has four helical flagella distributed over the cell surface, and swims by rotating them. When rotated counterclockwise the flagella coalesce into a propulsive bundle, producing a relatively straight “run,” and when rotated clockwise they fly apart, resulting in a “tumble” which reorients the cell with little translocation. A stochastic process generates the runs and tumbles, and in a chemoeffector gradient, runs that carry the cell in a favorable direction are extended. The cell senses spatial gradients as temporal changes in receptor occupancy and changes the probability of counterclockwise rotation (the bias) on a fast timescale, but adaptation returns the bias to baseline on a slow timescale, enabling the cell to detect and respond to further concentration changes. The overall structure of the signal transduction pathways is well characterized in E. coli, but important details are still not understood. Only recently has a source of gain in the signal transduction network been identified experimentally, and here we present a mathematical model based on dynamic assembly of receptor teams that can explain this observation. PMID:15111386

Dynamic receptor team formation can explain the high signal transduction gain in Escherichia coli.

PubMed

Albert, Réka; Chiu, Yu-Wen; Othmer, Hans G

2004-05-01

Evolution has provided many organisms with sophisticated sensory systems that enable them to respond to signals in their environment. The response frequently involves alteration in the pattern of movement, either by directed movement, a process called taxis, or by altering the speed or frequency of turning, which is called kinesis. Chemokinesis has been most thoroughly studied in the peritrichous bacterium Escherichia coli, which has four helical flagella distributed over the cell surface, and swims by rotating them. When rotated counterclockwise the flagella coalesce into a propulsive bundle, producing a relatively straight "run," and when rotated clockwise they fly apart, resulting in a "tumble" which reorients the cell with little translocation. A stochastic process generates the runs and tumbles, and in a chemoeffector gradient, runs that carry the cell in a favorable direction are extended. The cell senses spatial gradients as temporal changes in receptor occupancy and changes the probability of counterclockwise rotation (the bias) on a fast timescale, but adaptation returns the bias to baseline on a slow timescale, enabling the cell to detect and respond to further concentration changes. The overall structure of the signal transduction pathways is well characterized in E. coli, but important details are still not understood. Only recently has a source of gain in the signal transduction network been identified experimentally, and here we present a mathematical model based on dynamic assembly of receptor teams that can explain this observation.

A New Simulation Framework for the Electron-Ion Collider

NASA Astrophysics Data System (ADS)

Arrington, John

2017-09-01

Last year, a collaboration between Physics Division and High-Energy Physics at Argonne was formed to enable significantly broader contributions to the development of the Electron-Ion Collider. This includes efforts in accelerator R&D, theory, simulations, and detector R&D. I will give a brief overview of the status of these efforts, with emphasis on the aspects aimed at enabling the community to more easily become involved in evaluation of physics, detectors, and details of spectrometer designs. We have put together a new, easy-to-use simulation framework using flexible software tools. The goal is to enable detailed simulations to evaluate detector performance and compare detector designs. In addition, a common framework capable of providing detailed simulations of different spectrometer designs will allow for fully consistent evaluations of the physics reach of different spectrometer designs or detector systems for a variety of physics channels. In addition, new theory efforts will provide self-consistent models of GPDs (including QCD evolution) and TMDs in nucleons and light nuclei, as well as providing more detailed physics input for the evaluation of some new observables. This material is based upon work supported by Laboratory Directed Research and Development (LDRD) funding from Argonne National Laboratory, provided by the Director, Office of Science, of the U.S. Department of Energy under Contract DE-AC02-06CH11357.

Physical, Physiological, and Dietary Comparisons Between Marine Corps Forces Special Operations Command Critical Skills Operators and Enablers.

PubMed

Royer, Scott D; Thomas, D Travis; Winters, Joshua D; Abt, John P; Best, Stuart; Poploski, Kathleen M; Zalaiskalns, Andrejs; Lephart, Scott M

2018-04-04

Tactical demands of a Marine Corps Forces Special Operations Command (MARSOC) Critical Skills Operator (CSO) require high levels of physical performance. During combat deployments, teams of CSOs are supplemented with enablers who specialize in mission-specific tasks. MARSOC CSOs and enablers serve alongside each other in extreme combat environments, often enduring the same physical demands, but the selection process for each group is very different. The purpose of this observational study was to quantify the physical, physiological, and dietary differences of MARSOC CSOs and enablers, as this may have a direct impact on tactical performance and provide important information to shape future research. Fat free mass (FFM), fat mass (FM), fat mass index (FMI), fat free mass index (FFMI), anaerobic power (AP), anaerobic capacity (AC), aerobic capacity (VO2max), knee flexion (KF), knee extension (KE), trunk extension (TE), and trunk flexion (TF) isokinetic strength were collected. Dietary intake was collected using automated self-administered 24-hr dietary recalls (ASA24) for a subgroup of subjects. Testing on 164 male CSOs (age: 27.5 ± 3.8 yr, height: 178.7 ± 6.5 cm, mass: 85.7 ± 9.1 kg, and 7.6 ± 2.9 yr of military service) and 51 male enablers (age: 27.8 ± 5.4 yr, height: 178.4 ± 8.5 cm, mass: 83.8 ± 11.8 kg, and 7.9 ± 5.4 yr of military service) showed there were no significant differences for age, height, mass, or years of military service. (p> 0.05). CSOs demonstrated greater physiological performance in AP (W/kg) (p= 0.020), AC (W/kg) (p = 0.001), and VO2max (ml/kg/min) (p = 0.018). There were no significant differences in FM and FFM (p > 0.05), however CSOs demonstrated significantly higher FFMI (p = 0.011). CSOs also demonstrated greater KF (%BW) (p = 0.001), KE (%BW) (p = 0.001), TE (%BW) (p = 0.010), and TF (%BW) (p = 0.016). No differences in energy or macronutrient intake were observed in the subgroup. MARSOC CSOs demonstrated significantly greater FFMI, AP, AC, VO2max, KF, KE, TE, and TF compared with enablers. Dietary intake was consistent between groups, but fueling concerns were identified for all personnel in the subgroup. These findings suggest the need for future studies to examine what physiological and strength thresholds are necessary to operate effectively as a member of a MSOT and determine the relationship between specific performance deficits and risk of injury. In addition, the integration of nutrition strategies that augment and optimize the performance of both CSOs and enablers may be beneficial.

Radar velocity determination using direction of arrival measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doerry, Armin W.; Bickel, Douglas L.; Naething, Richard M.

The various technologies presented herein relate to utilizing direction of arrival (DOA) data to determine various flight parameters for an aircraft A plurality of radar images (e.g., SAR images) can be analyzed to identify a plurality of pixels in the radar images relating to one or more ground targets. In an embodiment, the plurality of pixels can be selected based upon the pixels exceeding a SNR threshold. The DOA data in conjunction with a measurable Doppler frequency for each pixel can be obtained. Multi-aperture technology enables derivation of an independent measure of DOA to each pixel based on interferometric analysis.more » This independent measure of DOA enables decoupling of the aircraft velocity from the DOA in a range-Doppler map, thereby enabling determination of a radar velocity. The determined aircraft velocity can be utilized to update an onboard INS, and to keep it aligned, without the need for additional velocity-measuring instrumentation.« less

Detection of F-region electron density irregularities using incoherent-scatter radar

NASA Astrophysics Data System (ADS)

Gudivada, Krishna Prasad

Incoherent-scatter radar data from Poker Flat, Alaska has been used to determine size distributions of electron density structures in the evening time sector of the auroral zone. At high latitudes ionospheric plasma typically moves east-west with speeds of several hundred meters per second. Density irregularities that rapidly move through the radar beam are therefore observed as time-varying power fluctuations. The new phased array radar used for this study has been operated with several antenna directions with successive pulses transmitted in each direction. It is therefore possible to observe plasma Doppler velocities in multiple directions and determine the vector direction of the plasma motion. This near-simultaneous observation of the plasma velocity in conjunction with the electron density height profile data enable a new technique to determine the scale sizes of electron density fluctuations that move horizontally through the radar beam. The study focuses on the collision-less F-region ionosphere where the plasma drift is approximately constant with altitude. The experimental technique limits the range of scale sizes that may be studied to relatively large-scale sizes (i.e. greater than few tens of km). Results show that during magnetically disturbed conditions (Kp ≥ 4) when westward plasma velocities are relatively high (500-1000 m/s) the scale sizes of irregularities (often called plasma blobs) are in the range of 100-300 km and predominantly originate from the polar cap and are transported over long distances (˜1000 km) due to the long chemical recombination times (30-90 minutes). Some irregularities are caused by local auroral particle precipitation and have been identified with associated electron temperature enhancements. For cases of low magnetic activity (Kp ≤ 1), when the radar is located in a region of low plasma velocities (100-500 m/s) well south of the auroral oval (essentially a mid-latitude type ionosphere), the density distribution is always biased strongly toward small-scale sizes (less than 50 km).

Investigation of enablers of knowledge transfer in the medical industry.

PubMed

Tuan, Han-Wen

2008-01-01

This paper presents a research model for investigating the relationship between organisational enablers and the Knowledge Transfer (KT) Performance (KTP) in the medical industry. The enablers include leadership, organisational culture, Information Technology (IT) and individual performance measurement, and KTP is determined by individual capability, organisational capability and product/service innovation. This paper chose professional medical personnel as the research subject to determine whether or not these enablers affect KT. The findings show that only leadership directly affects the KTP, with IT also impacting both organisational capability and product/service innovation. The implications of these findings are discussed based on interviews with experts and practitioners.

GaN/NbN epitaxial semiconductor/superconductor heterostructures

NASA Astrophysics Data System (ADS)

Yan, Rusen; Khalsa, Guru; Vishwanath, Suresh; Han, Yimo; Wright, John; Rouvimov, Sergei; Katzer, D. Scott; Nepal, Neeraj; Downey, Brian P.; Muller, David A.; Xing, Huili G.; Meyer, David J.; Jena, Debdeep

2018-03-01

Epitaxy is a process by which a thin layer of one crystal is deposited in an ordered fashion onto a substrate crystal. The direct epitaxial growth of semiconductor heterostructures on top of crystalline superconductors has proved challenging. Here, however, we report the successful use of molecular beam epitaxy to grow and integrate niobium nitride (NbN)-based superconductors with the wide-bandgap family of semiconductors—silicon carbide, gallium nitride (GaN) and aluminium gallium nitride (AlGaN). We apply molecular beam epitaxy to grow an AlGaN/GaN quantum-well heterostructure directly on top of an ultrathin crystalline NbN superconductor. The resulting high-mobility, two-dimensional electron gas in the semiconductor exhibits quantum oscillations, and thus enables a semiconductor transistor—an electronic gain element—to be grown and fabricated directly on a crystalline superconductor. Using the epitaxial superconductor as the source load of the transistor, we observe in the transistor output characteristics a negative differential resistance—a feature often used in amplifiers and oscillators. Our demonstration of the direct epitaxial growth of high-quality semiconductor heterostructures and devices on crystalline nitride superconductors opens up the possibility of combining the macroscopic quantum effects of superconductors with the electronic, photonic and piezoelectric properties of the group III/nitride semiconductor family.

GaN/NbN epitaxial semiconductor/superconductor heterostructures.

PubMed

Yan, Rusen; Khalsa, Guru; Vishwanath, Suresh; Han, Yimo; Wright, John; Rouvimov, Sergei; Katzer, D Scott; Nepal, Neeraj; Downey, Brian P; Muller, David A; Xing, Huili G; Meyer, David J; Jena, Debdeep

2018-03-07

Epitaxy is a process by which a thin layer of one crystal is deposited in an ordered fashion onto a substrate crystal. The direct epitaxial growth of semiconductor heterostructures on top of crystalline superconductors has proved challenging. Here, however, we report the successful use of molecular beam epitaxy to grow and integrate niobium nitride (NbN)-based superconductors with the wide-bandgap family of semiconductors-silicon carbide, gallium nitride (GaN) and aluminium gallium nitride (AlGaN). We apply molecular beam epitaxy to grow an AlGaN/GaN quantum-well heterostructure directly on top of an ultrathin crystalline NbN superconductor. The resulting high-mobility, two-dimensional electron gas in the semiconductor exhibits quantum oscillations, and thus enables a semiconductor transistor-an electronic gain element-to be grown and fabricated directly on a crystalline superconductor. Using the epitaxial superconductor as the source load of the transistor, we observe in the transistor output characteristics a negative differential resistance-a feature often used in amplifiers and oscillators. Our demonstration of the direct epitaxial growth of high-quality semiconductor heterostructures and devices on crystalline nitride superconductors opens up the possibility of combining the macroscopic quantum effects of superconductors with the electronic, photonic and piezoelectric properties of the group III/nitride semiconductor family.

A structural insight into mechanical strength of graphene-like carbon and carbon nitride networks

NASA Astrophysics Data System (ADS)

Rahaman, Obaidur; Mortazavi, Bohayra; Dianat, Arezoo; Cuniberti, Gianaurelio; Rabczuk, Timon

2017-02-01

Graphene, one of the strongest materials ever discovered, triggered the exploration of many 2D materials in the last decade. However, the successful synthesis of a stable nanomaterial requires a rudimentary understanding of the relationship between its structure and strength. In the present study, we investigate the mechanical properties of eight different carbon-based 2D nanomaterials by performing extensive density functional theory calculations. The considered structures were just recently either experimentally synthesized or theoretically predicted. The corresponding stress-strain curves and elastic moduli are reported. They can be useful in training force field parameters for large scale simulations. A comparative analysis of these results revealed a direct relationship between atomic density per area and elastic modulus. Furthermore, for the networks that have an armchair and a zigzag orientation, we observed that they were more stretchable in the zigzag direction than the armchair direction. A critical analysis of the angular distributions and radial distribution functions suggested that it could be due to the higher ability of the networks to suppress the elongations of the bonds in the zigzag direction by deforming the bond angles. The structural interpretations provided in this work not only improve the general understanding of a 2D material’s strength but also enables us to rationally design them for higher qualities.

LONG-TERM STABLE EQUILIBRIA FOR SYNCHRONOUS BINARY ASTEROIDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobson, Seth A.; Scheeres, Daniel J.

Synchronous binary asteroids may exist in a long-term stable equilibrium, where the opposing torques from mutual body tides and the binary YORP (BYORP) effect cancel. Interior of this equilibrium, mutual body tides are stronger than the BYORP effect and the mutual orbit semimajor axis expands to the equilibrium; outside of the equilibrium, the BYORP effect dominates the evolution and the system semimajor axis will contract to the equilibrium. If the observed population of small (0.1-10 km diameter) synchronous binaries are in static configurations that are no longer evolving, then this would be confirmed by a null result in the observationalmore » tests for the BYORP effect. The confirmed existence of this equilibrium combined with a shape model of the secondary of the system enables the direct study of asteroid geophysics through the tidal theory. The observed synchronous asteroid population cannot exist in this equilibrium if described by the canonical 'monolithic' geophysical model. The 'rubble pile' geophysical model proposed by Goldreich and Sari is sufficient, however it predicts a tidal Love number directly proportional to the radius of the asteroid, while the best fit to the data predicts a tidal Love number inversely proportional to the radius. This deviation from the canonical and Goldreich and Sari models motivates future study of asteroid geophysics. Ongoing BYORP detection campaigns will determine whether these systems are in an equilibrium, and future determination of secondary shapes will allow direct determination of asteroid geophysical parameters.« less

Disease management: remote monitoring in heart failure patients with implantable defibrillators, resynchronization devices, and haemodynamic monitors.

PubMed

Abraham, William T

2013-06-01

Heart failure represents a major public health concern, associated with high rates of morbidity and mortality. A particular focus of contemporary heart failure management is reduction of hospital admission and readmission rates. While optimal medical therapy favourably impacts the natural history of the disease, devices such as cardiac resynchronization therapy devices and implantable cardioverter defibrillators have added incremental value in improving heart failure outcomes. These devices also enable remote patient monitoring via device-based diagnostics. Device-based measurement of physiological parameters, such as intrathoracic impedance and heart rate variability, provide a means to assess risk of worsening heart failure and the possibility of future hospitalization. Beyond this capability, implantable haemodynamic monitors have the potential to direct day-to-day management of heart failure patients to significantly reduce hospitalization rates. The use of a pulmonary artery pressure measurement system has been shown to significantly reduce the risk of heart failure hospitalization in a large randomized controlled study, the CardioMEMS Heart Sensor Allows Monitoring of Pressure to Improve Outcomes in NYHA Class III Heart Failure Patients (CHAMPION) trial. Observations from a pilot study also support the potential use of a left atrial pressure monitoring system and physician-directed patient self-management paradigm; these observations are under further investigation in the ongoing LAPTOP-HF trial. All these devices depend upon high-intensity remote monitoring for successful detection of parameter deviations and for directing and following therapy.

Patterned Liquid Metal Contacts for Printed Carbon Nanotube Transistors.

PubMed

Andrews, Joseph B; Mondal, Kunal; Neumann, Taylor V; Cardenas, Jorge A; Wang, Justin; Parekh, Dishit P; Lin, Yiliang; Ballentine, Peter; Dickey, Michael D; Franklin, Aaron D

2018-05-14

Flexible and stretchable electronics are poised to enable many applications that cannot be realized with traditional, rigid devices. One of the most promising options for low-cost stretchable transistors are printed carbon nanotubes (CNTs). However, a major limiting factor in stretchable CNT devices is the lack of a stable and versatile contact material that forms both the interconnects and contact electrodes. In this work, we introduce the use of eutectic gallium-indium (EGaIn) liquid metal for electrical contacts to printed CNT channels. We analyze thin-film transistors (TFTs) fabricated using two different liquid metal deposition techniques-vacuum-filling polydimethylsiloxane (PDMS) microchannel structures and direct-writing liquid metals on the CNTs. The highest performing CNT-TFT was realized using vacuum-filled microchannel deposition with an in situ annealing temperature of 150 °C. This device exhibited an on/off ratio of more than 10 4 and on-currents as high as 150 μA/mm-metrics that are on par with other printed CNT-TFTs. Additionally, we observed that at room temperature the contact resistances of the vacuum-filled microchannel structures were 50% lower than those of the direct-write structures, likely due to the poor adhesion between the materials observed during the direct-writing process. The insights gained in this study show that stretchable electronics can be realized using low-cost and solely solution processing techniques. Furthermore, we demonstrate methods that can be used to electrically characterize semiconducting materials as transistors without requiring elevated temperatures or cleanroom processes.

Measuring the High-Mass IMF in Low-Metallicity Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Weisz, Daniel

2017-08-01

We propose to measure the stellar initial mass function above >1-2 Msun in 46 nearby dwarf galaxies with archival HST observations. This novel approach leverages the redundant age information provided by the main sequence and blue core helium burning stars <500 years old to break the well-known degeneracy between the IMF and star formation history (SFH), enabling a direct measurement of the high-mass IMF in dwarf galaxies. We will be able to constrain the high-mass IMF slope to a precision better than 0.1 to 0.3 dex in each galaxy. Our sample spans a factor of 6 in metallicity ( 5-30% Zsun), 4 decades in star formation rate, and 3 decades in both stellar and gas mass, allowing us to explore the IMF over a wide range of extreme environments.Current observational evidence suggests that nearby dwarf galaxies are the most likely candidates to host significant and systematic variations in the high-mass IMF (e.g., Halpha/UV ratios). However, to date there have been no direct measurements of the high-mass IMF in environments with lower star formation rates and/or more metal poor than the Magellanic Clouds. Our program remedies this shortcoming allowing us to (1) make the first-ever measurement of the high-mass IMF in extremely metal-poor environments; (2) empirically quantify environmental the (lack of) variations in the high-mass IMF; (3) directly test the integrated galactic mass initial mass function (IGIMF), which predicts environmental sensitivity of the IMF in dwarf galaxies.

Elucidation of proliferative capability of mononuclear tetraploid cells, emerging spontaneously from diploid cells, using image cytometry and fluorescence in situ hybridization.

PubMed

Ito, Hideaki; Oga, Atsunori; Furuya, Tomoko; Ikemoto, Kenzo; Amakawa, Genta; Chochi, Yasuyo; Kawauchi, Shigeto; Sasaki, Kohsuke

2013-06-01

Proliferation of tetraploid cells (TCs) emerging from diploid cells is considered to be a critical event toward tumourigenesis, or cancer progression. Recently, several studies have reported that binuclear TCs emerging from normal cells are capable of mitosis, however, it has not been confirmed directly whether mononuclear TCs emerging from normal cells could proliferate, even cancer cells. The aim of this study is to detect mononuclear TCs in vitro, spontaneously emerging from diploid cells and to elucidate their proliferative capability directly. For this purpose, we have developed a novel method. In this study, two completely disomic cell lines were used, TIG-7, a fibroblast cell line and CAL-51, a breast cancer cell line. Cells were cultured on microscope slides and their DNA content was determined using an image cytometer. On the same slides, chromosome numbers were scored using centromere fluorescence in situ hybridization (FISH). For evaluating proliferative capability of TCs, bromodeoxyuridine (BrdUrd) incorporation and colony-forming ability were examined. Using our method, spontaneous emergence of mononuclear TCs was detected in both TIG-7 and CAL-51. Colonies of TIG-7 TCs were not observed, but were observed of CAL-51 TCs. Our method enables detection of mononuclear TCs and elucidation of their proliferative capability, directly; this evidence reveals that mononuclear TIG-7 TCs do not proliferate but that mononuclear CAL-51 TCs are able to. © 2013 Blackwell Publishing Ltd.

Optical diametric drive acceleration through action-reaction symmetry breaking

NASA Astrophysics Data System (ADS)

Wimmer, Martin; Regensburger, Alois; Bersch, Christoph; Miri, Mohammad-Ali; Batz, Sascha; Onishchukov, Georgy; Christodoulides, Demetrios N.; Peschel, Ulf

2013-12-01

Newton's third law of motion is one of the pillars of classical physics. This fundamental principle states that the forces two bodies exert on each other are equal and opposite. Had the resulting accelerations been oriented in the same direction, this would have instead led to a counterintuitive phenomenon, that of diametric drive. In such a hypothetical arrangement, two interacting particles constantly accelerate each other in the same direction through a violation of the action-reaction symmetry. Although in classical mechanics any realization of this process requires one of the two particles to have a negative mass and hence is strictly forbidden, it could nevertheless be feasible in periodic structures where the effective mass can also attain a negative sign. Here we report the first experimental observation of such diametric drive acceleration for pulses propagating in a nonlinear optical mesh lattice. The demonstrated reversal of action-reaction symmetry could enable altogether new possibilities for frequency conversion and pulse-steering applications.

Laboratory Studies of Cometary Materials - Continuity Between Asteroid and Comet

NASA Technical Reports Server (NTRS)

Messenger, Scott; Walker, Robert M.

2015-01-01

Laboratory analysis of cometary samples have been enabled by collection of cometary dust in the stratosphere by high altitude aircraft and by the direct sampling of the comet Wild-2 coma by the NASA Stardust spacecraft. Cometary materials are composed of a complex assemblage of highly primitive, unprocessed interstellar and primordial solar system materials as well as a variety of high temperature phases that must have condensed in the inner regions of the protoplanetary disk. These findings support and contradict conclusions of comet properties based solely on astronomical observations. These sample return missions have instead shown that there is a continuity of properties between comets and asteroids, where both types of materials show evidence for primitive and processed materials. Furthermore, these findings underscore the importance and value of direct sample return. There will be great value in comparing the findings of the Stardust cometary coma sample return mission with those of future asteroid surface sample returns OSIRIS-REx and Hayabusa II as well as future comet nucleus sample returns.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Jaehong; Reid, Obadiah G.; Blackburn, Jeffrey L.

The strong quantum confinement and low dielectric screening impart single-walled carbon nanotubes with exciton-binding energies substantially exceeding kBT at room temperature. Despite these large binding energies, reported photoluminescence quantum yields are typically low and some studies suggest that photoexcitation of carbon nanotube excitonic transitions can produce free charge carriers. Here we report the direct measurement of long-lived free-carrier generation in chirality-pure, single-walled carbon nanotubes in a low dielectric solvent. Time-resolved microwave conductivity enables contactless and quantitative measurement of the real and imaginary photoconductance of individually suspended nanotubes. We found that the conditions of the microwave conductivity measurement allow us tomore » avoid the complications of most previous measurements of nanotube free-carrier generation, including tube–tube/tube–electrode contact, dielectric screening by nearby excitons and many-body interactions. At low photon fluence (approximately 0.05 excitons per μm length of tubes), we directly observe free carriers on excitation of the first and second carbon nanotube exciton transitions.« less

Tubular astigmatism-tunable fluidic lens.

PubMed

Kopp, Daniel; Zappe, Hans

2016-06-15

We demonstrate a new means to fabricate three-dimensional liquid lenses which may be tuned in focal length and astigmatism. Using actuation by electrowetting-on-dielectrics, astigmatism in arbitrary directions may be tuned independently, with almost no cross talk between orthogonal orientations. The lens is based on electrodes structured on planar polyimide foils and subsequently rolled, enabling high-resolution patterning of complex electrodes along the azimuthal and radial directions of the lens. Based on a design established through fluidic and optical simulations, the astigmatism tuning is experimentally verified by a change of the corresponding Zernike coefficients measured using a Shack-Hartmann wavefront sensor. It was seen that the back focal length can be tuned by 5 mm and 0° and 45° astigmatism by 3 μm through application of voltages in the range of 50  V_rms. It was observed that the cross talk with other aberrations is very low, suggesting a novel means for astigmatism control in imaging systems.

Effects of buoyancy-driven convection on nucleation and growth of protein crystals.

PubMed

Nanev, Christo N; Penkova, Anita; Chayen, Naomi

2004-11-01

Protein crystallization has been studied in presence or absence of buoyancy-driven convection. Gravity-driven flow was created, or suppressed, in protein solutions by means of vertically directed density gradients that were caused by generating suitable temperature gradients. The presence of enhanced mixing was demonstrated directly by experiments with crustacyanin, a blue-colored protein, and other materials. Combined with the vertical tube position the enhanced convection has two main effects. First, it reduces the number of nucleated hen-egg-white lysozyme (HEWL) crystals, as compared with those in a horizontal capillary. By enabling better nutrition from the protein in the solution, convection results in growth of fewer larger HEWL crystals. Second, we observe that due to convection, trypsin crystals grow faster. Suppression of convection, achieved by decreasing solution density upward in the capillary, can to some extent mimic conditions of growth in microgravity. Thus, impurity supply, which may have a detrimental effect on crystal quality, was avoided.

Pendant Hydrogen-Bond Donors in Cobalt Catalysts Independently Enhance CO2 Reduction

PubMed Central

2018-01-01

The bioinspired incorporation of pendant proton donors into transition metal catalysts is a promising strategy for converting environmentally deleterious CO2 to higher energy products. However, the mechanism of proton transfer in these systems is poorly understood. Herein, we present a series of cobalt complexes with varying pendant secondary and tertiary amines in the ligand framework with the aim of disentangling the roles of the first and second coordination spheres in CO2 reduction catalysis. Electrochemical and kinetic studies indicate that the rate of catalysis shows a first-order dependence on acid, CO2, and the number of pendant secondary amines, respectively. Density functional theory studies explain the experimentally observed trends and indicate that pendant secondary amines do not directly transfer protons to CO2, but instead bind acid molecules from solution. Taken together, these results suggest a mechanism in which noncooperative pendant amines facilitate a hydrogen-bonding network that enables direct proton transfer from acid to the activated CO2 substrate. PMID:29632886

Pendant Hydrogen-Bond Donors in Cobalt Catalysts Independently Enhance CO2 Reduction.

PubMed

Chapovetsky, Alon; Welborn, Matthew; Luna, John M; Haiges, Ralf; Miller, Thomas F; Marinescu, Smaranda C

2018-03-28

The bioinspired incorporation of pendant proton donors into transition metal catalysts is a promising strategy for converting environmentally deleterious CO 2 to higher energy products. However, the mechanism of proton transfer in these systems is poorly understood. Herein, we present a series of cobalt complexes with varying pendant secondary and tertiary amines in the ligand framework with the aim of disentangling the roles of the first and second coordination spheres in CO 2 reduction catalysis. Electrochemical and kinetic studies indicate that the rate of catalysis shows a first-order dependence on acid, CO 2 , and the number of pendant secondary amines, respectively. Density functional theory studies explain the experimentally observed trends and indicate that pendant secondary amines do not directly transfer protons to CO 2 , but instead bind acid molecules from solution. Taken together, these results suggest a mechanism in which noncooperative pendant amines facilitate a hydrogen-bonding network that enables direct proton transfer from acid to the activated CO 2 substrate.

High-Resolution Imaging of Polyethylene Glycol Coated Dendrimers via Combined Atomic Force and Scanning Tunneling Microscopy

PubMed Central

Zhong, Qian; Yin, Nai-Ning; Karsai, Arpad; da Rocha, Sandro R. P.; Liu, Gang-yu

2015-01-01

Dendrimers have shown great promise as drug delivery vehicles in recent years because they can be synthesized with designed size and functionalities for optimal transportation, targeting, and biocompatibility. One of the most well-known termini used for biocompatibility is polyethylene glycol (PEG), whose performance is affected by its actual conformation. However, the conformation of individual PEG bound to soft materials such as dendrimers has not been directly observed. Using atomic force microscopy (AFM) and scanning tunneling microscopy (STM), this work characterizes the structure adopted by PEGylated dendrimers with the highest resolution reported to date. AFM imaging enables visualization of the individual dendrimers, as well as the differentiation and characterization of the dendrimer core and PEG shell. STM provides direct imaging of the PEG extensions with high-resolution. Collectively, this investigation provides important insight into the structure of coated dendrimers, which is crucial for the design and development of better drug delivery vehicles. PMID:25685559

Case study: use of problem-based learning to develop students' technical and professional skills

NASA Astrophysics Data System (ADS)

Warnock, James N.; Mohammadi-Aragh, M. Jean

2016-03-01

Problem-based learning (PBL) is a pedagogy that has attracted attention for many biomedical engineering curricula. The aim of the current study was to address the research question, 'Does PBL enable students to develop desirable professional engineering skills?' The desirable skills identified were communication, teamwork, problem solving and self-directed learning. Forty-seven students enrolled in a biomedical materials course participated in the case study. Students worked in teams to complete a series of problems throughout the semester. The results showed that students made significant improvements in their problem-solving skills, written communication and self-directed learning. Students also demonstrated an ability to work in teams and communicate orally. In conclusion, this case study provides empirical evidence of the efficacy of PBL on student learning. We discuss findings from our study and provide observations of student performance and perceptions that could be useful for faculty and researchers interested in PBL for biomedical engineering education.

Optogenetic control of contractile function in skeletal muscle

PubMed Central

Bruegmann, Tobias; van Bremen, Tobias; Vogt, Christoph C.; Send, Thorsten; Fleischmann, Bernd K.; Sasse, Philipp

2015-01-01

Optogenetic stimulation allows activation of cells with high spatial and temporal precision. Here we show direct optogenetic stimulation of skeletal muscle from transgenic mice expressing the light-sensitive channel Channelrhodopsin-2 (ChR2). Largest tetanic contractions are observed with 5-ms light pulses at 30 Hz, resulting in 84% of the maximal force induced by electrical stimulation. We demonstrate the utility of this approach by selectively stimulating with a light guide individual intralaryngeal muscles in explanted larynges from ChR2-transgenic mice, which enables selective opening and closing of the vocal cords. Furthermore, systemic injection of adeno-associated virus into wild-type mice provides sufficient ChR2 expression for optogenetic opening of the vocal cords. Thus, direct optogenetic stimulation of skeletal muscle generates large force and provides the distinct advantage of localized and cell-type-specific activation. This technology could be useful for therapeutic purposes, such as restoring the mobility of the vocal cords in patients suffering from laryngeal paralysis. PMID:26035411

Oceanic rafting by a coastal community

PubMed Central

Fraser, Ceridwen I.; Nikula, Raisa; Waters, Jonathan M.

2011-01-01

Oceanic rafting is thought to play a fundamental role in assembling the biological communities of isolated coastal ecosystems. Direct observations of this key ecological and evolutionary process are, however, critically lacking. The importance of macroalgal rafting as a dispersal mechanism has remained uncertain, largely owing to lack of knowledge about the capacity of fauna to survive long voyages at sea and successfully make landfall and establish. Here, we directly document the rafting of a diverse assemblage of intertidal organisms across several hundred kilometres of open ocean, from the subantarctic to mainland New Zealand. Multispecies analyses using phylogeographic and ecological data indicate that 10 epifaunal invertebrate species rafted on six large bull kelp specimens for several weeks from the subantarctic Auckland and/or Snares Islands to the Otago coast of New Zealand, a minimum distance of some 400–600 km. These genetic data are the first to demonstrate that passive rafting can enable simultaneous trans-oceanic transport and landfall of numerous coastal taxa. PMID:20843850

Oceanic rafting by a coastal community.

PubMed

Fraser, Ceridwen I; Nikula, Raisa; Waters, Jonathan M

2011-03-07

Oceanic rafting is thought to play a fundamental role in assembling the biological communities of isolated coastal ecosystems. Direct observations of this key ecological and evolutionary process are, however, critically lacking. The importance of macroalgal rafting as a dispersal mechanism has remained uncertain, largely owing to lack of knowledge about the capacity of fauna to survive long voyages at sea and successfully make landfall and establish. Here, we directly document the rafting of a diverse assemblage of intertidal organisms across several hundred kilometres of open ocean, from the subantarctic to mainland New Zealand. Multispecies analyses using phylogeographic and ecological data indicate that 10 epifaunal invertebrate species rafted on six large bull kelp specimens for several weeks from the subantarctic Auckland and/or Snares Islands to the Otago coast of New Zealand, a minimum distance of some 400-600 km. These genetic data are the first to demonstrate that passive rafting can enable simultaneous trans-oceanic transport and landfall of numerous coastal taxa.

Optofluidic microscope with 3D spatial resolution.

PubMed

Vig, Asger Laurburg; Marie, Rodolphe; Jensen, Eric; Kristensen, Anders

2010-03-01

This paper reports on-chip based optical detection with three-dimensional spatial resolution by integration of an optofluidic microscope (OFM) in a microfluidic pinched flow fractionation (PFF) separation device. This setup also enables on-chip particle image velocimetry (PIV). The position in the plane perpendicular to the flow direction and the velocity along the flow direction of separated fluorescent labeled polystyrene microspheres with diameters of 1 microm , 2.1 microm , 3 microm and 4 microm is determined by the OFM. These results are bench marked against those obtained with a PFF device using conventional fluorescence microscope readout. The size separated microspheres are detected by OFM with an accuracy of

Implementing Kernel Methods Incrementally by Incremental Nonlinear Projection Trick.

PubMed

Kwak, Nojun

2016-05-20

Recently, the nonlinear projection trick (NPT) was introduced enabling direct computation of coordinates of samples in a reproducing kernel Hilbert space. With NPT, any machine learning algorithm can be extended to a kernel version without relying on the so called kernel trick. However, NPT is inherently difficult to be implemented incrementally because an ever increasing kernel matrix should be treated as additional training samples are introduced. In this paper, an incremental version of the NPT (INPT) is proposed based on the observation that the centerization step in NPT is unnecessary. Because the proposed INPT does not change the coordinates of the old data, the coordinates obtained by INPT can directly be used in any incremental methods to implement a kernel version of the incremental methods. The effectiveness of the INPT is shown by applying it to implement incremental versions of kernel methods such as, kernel singular value decomposition, kernel principal component analysis, and kernel discriminant analysis which are utilized for problems of kernel matrix reconstruction, letter classification, and face image retrieval, respectively.

Nanophotonic Optical Isolator Controlled by the Internal State of Cold Atoms

NASA Astrophysics Data System (ADS)

Sayrin, Clément; Junge, Christian; Mitsch, Rudolf; Albrecht, Bernhard; O'Shea, Danny; Schneeweiss, Philipp; Volz, Jürgen; Rauschenbeutel, Arno

2015-10-01

The realization of nanophotonic optical isolators with high optical isolation even at ultralow light levels and low optical losses is an open problem. Here, we employ the link between the local polarization of strongly confined light and its direction of propagation to realize low-loss nonreciprocal transmission through a silica nanofiber at the single-photon level. The direction of the resulting optical isolator is controlled by the spin state of cold atoms. We perform our experiment in two qualitatively different regimes, i.e., with an ensemble of cold atoms where each atom is weakly coupled to the waveguide and with a single atom strongly coupled to the waveguide mode. In both cases, we observe simultaneously high isolation and high forward transmission. The isolator concept constitutes a nanoscale quantum optical analog of microwave ferrite resonance isolators, can be implemented with all kinds of optical waveguides and emitters, and might enable novel integrated optical devices for fiber-based classical and quantum networks.

F-16XL and F-18 High Speed Acoustic Flight Test Databases

NASA Technical Reports Server (NTRS)

Kelly, J. J.; Wilson, M. R.; Rawls, J., Jr.; Norum, T. D.; Golub, R. A.

1999-01-01

This report presents the recorded acoustic data and the computed narrow-band and 1/3-octave band spectra produced by F-18 and F-16XL aircraft in subsonic flight over an acoustic array. Both broadband-shock noise and turbulent mixing noise are observed in the spectra. Radar and c-band tracking systems provided the aircraft position which enabled directivity and smear angles from the aircraft to each microphone to be computed. These angles are based on source emission time and thus give some idea about the directivity of the radiated sound field due to jet noise. A follow-on static test was also conducted where acoustic and engine data were obtained. The acoustic data described in the report has application to community noise analysis, noise source characterization and validation of prediction models. A detailed description of the signal processing procedures is provided. Follow-on static tests of each aircraft were also conducted for which engine data and far-field acoustic data are presented.

Collective Dynamics of Periplasmic Glutamine Binding Protein upon Domain Closure

PubMed Central

Loeffler, Hannes H.; Kitao, Akio

2009-01-01

The glutamine binding protein is a vital component of the associated ATP binding cassette transport systems responsible for the uptake of glutamine into the cell. We have investigated the global movements of this protein by molecular dynamics simulations and principal component analysis (PCA). We confirm that the most dominant mode corresponds to the biological function of the protein, i.e., a hinge-type motion upon ligand binding. The closure itself was directly observed from two independent trajectories whereby PCA was used to elucidate the nature of this closing reaction. Two intermediary states are identified and described in detail. The ligand binding induces the structural change of the hinge regions from a discontinuous β-sheet to a continuous one, which also enhances softness of the hinge and modifies the direction of hinge motion to enable closing. We also investigated the convergence behavior of PCA modes, which were found to converge rather quickly when the associated magnitudes of the eigenvalues are well separated. PMID:19883597

Photoinduced Spontaneous Free-Carrier Generation in Semiconducting Single-Walled Carbon Nanotubes

DOE PAGES

Park, Jaehong; Reid, Obadiah G.; Blackburn, Jeffrey L.; ...

2015-11-04

The strong quantum confinement and low dielectric screening impart single-walled carbon nanotubes with exciton-binding energies substantially exceeding kBT at room temperature. Despite these large binding energies, reported photoluminescence quantum yields are typically low and some studies suggest that photoexcitation of carbon nanotube excitonic transitions can produce free charge carriers. Here we report the direct measurement of long-lived free-carrier generation in chirality-pure, single-walled carbon nanotubes in a low dielectric solvent. Time-resolved microwave conductivity enables contactless and quantitative measurement of the real and imaginary photoconductance of individually suspended nanotubes. We found that the conditions of the microwave conductivity measurement allow us tomore » avoid the complications of most previous measurements of nanotube free-carrier generation, including tube–tube/tube–electrode contact, dielectric screening by nearby excitons and many-body interactions. At low photon fluence (approximately 0.05 excitons per μm length of tubes), we directly observe free carriers on excitation of the first and second carbon nanotube exciton transitions.« less

Pore Breathing of Metal-Organic Frameworks by Environmental Transmission Electron Microscopy.

PubMed

Parent, Lucas R; Pham, C Huy; Patterson, Joseph P; Denny, Michael S; Cohen, Seth M; Gianneschi, Nathan C; Paesani, Francesco

2017-10-11

Metal-organic frameworks (MOFs) have emerged as a versatile platform for the rational design of multifunctional materials, combining large specific surface areas with flexible, periodic frameworks that can undergo reversible structural transitions, or "breathing", upon temperature and pressure changes, and through gas adsorption/desorption processes. Although MOF breathing can be inferred from the analysis of adsorption isotherms, direct observation of the structural transitions has been lacking, and the underlying processes of framework reorganization in individual MOF nanocrystals is largely unknown. In this study, we describe the characterization and elucidation of these processes through the combination of in situ environmental transmission electron microscopy (ETEM) and computer simulations. This combined approach enables the direct monitoring of the breathing behavior of individual MIL-53(Cr) nanocrystals upon reversible water adsorption and temperature changes. The ability to characterize structural changes in single nanocrystals and extract lattice level information through in silico correlation provides fundamental insights into the relationship between pore size/shape and host-guest interactions.

The Tribal Lands Collaboratory: Building partnerships and developing tools to support local Tribal community response to climate change.

NASA Astrophysics Data System (ADS)

Jones, K. D.; Wee, B.; Kuslikis, A.

2015-12-01

Response of Tribal nations and Tribal communities to current and emerging climate change challenges requires active participation of stakeholders who have effective access to relevant data, information and analytical tools. The Tribal Lands Collaboratory (TLC), currently under development, is a joint effort between the American Indian Higher Education Consortium (AIHEC), the Environmental Systems Research Institute (Esri), and the National Ecological Observatory Network (NEON). The vision of the TLC is to create an integrative platform that enables coordination between multiple stakeholders (e.g. Tribal resource managers, Tribal College faculty and students, farmers, ranchers, and other local community members) to collaborate on locally relevant climate change issues. The TLC is intended to facilitate the transformation of data into actionable information that can inform local climate response planning. The TLC will provide the technical mechanisms to access, collect and analyze data from both internal and external sources (e.g. NASA's Giovanni climate data portal, Ameriflux or USA National Phenology Network) while also providing the social scaffolds to enable collaboration across Tribal communities and with members of the national climate change research community. The prototype project focuses on phenology, a branch of science focused on relationships between climate and the seasonal timing of biological phenomena. Monitoring changes in the timing and duration of phenological stages in plant and animal co­­­­mmunities on Tribal lands can provide insight to the direct impacts of climate change on culturally and economically significant Tribal resources . The project will leverage existing phenological observation protocols created by the USA-National Phenology Network and NEON to direct data collection efforts and will be tailored to the specific needs and concerns of the community. Phenology observations will be captured and managed within the Collaboratory environment where these data may then be correlated with regional climate data to investigate interactions between large-scale environmental changes and local impacts. Esri's Story Maps is a candidate mechanism for sharing of those findings among Tribal stakeholders.

Medical education in difficult circumstances: analysis of the experience of clinical medical students following the new innovative medical curriculum in Aksum, rural Ethiopia.

PubMed

Morgan, C; Teshome, M; Crocker-Buque, T; Bhudia, R; Singh, K

2018-05-31

In 2012, 12 medical schools were opened in Ethiopia to tackle the significant shortage of doctors. This included Aksum School of Medicine situated in Aksum, a rural town in Northern Ethiopia. The new Innovative Medical Curriculum (NIMC) is a four-year programme designed by the Ethiopian Federal Ministries of Health and Education. The curriculum is designed to train biomedical science graduates to become doctors in 4 years, with a focus on the healthcare needs of rural people living in poverty. This research was conducted at Aksum School of Medicine and included two hospitals (Aksum Referral Hospital and St Mary's District Hospital). This study focused on medical students during their clinical years across multiple specialities (61 Clerkship 1 students and 13 Clerkship 2 students). We used primarily qualitative research methods supplemented with quantitative measures. There were 3 stages of data collection over a 1 month period, this included qualitative group interviews, direct observation of students in a clinical setting and direct observation of skills sessions followed by a questionnaire on the sessions. We analysed the data by reconstructing the student experience and comparing it with the NIMC. The proposed typical week set out in the NIMC tended to differ from the real clinical experience of these students. Through qualitative group interview and direct observation of teaching, the main theme that was consistent throughout was the lack of doctors with specialist postgraduate training. Clinical need often took priority over education. However, students enjoyed taking early responsibility and gaining practical experience. Through direct observation of skills sessions and short questionnaires, these sessions were highly valuable to the students and they felt confident in carrying out the taught procedures in the future. The combination of poorly resourced hospitals and lack of specialist doctors provides a challenging environment for medical students to learn. However, it is a unique clinical experience that is rarely seen in developed countries and facilitates the acquirement of skills from an early stage. Supervision and specialist input is fundamental in enabling students to learn and this is a key area that was lacking in the students' clinical experience.

SWE-based Observation Data Delivery from the Instrument to the User - Sensor Web Technology in the NeXOS Project

NASA Astrophysics Data System (ADS)

Jirka, Simon; del Rio, Joaquin; Toma, Daniel; Martinez, Enoc; Delory, Eric; Pearlman, Jay; Rieke, Matthes; Stasch, Christoph

2017-04-01

The rapidly evolving technology for building Web-based (spatial) information infrastructures and Sensor Webs, there are new opportunities to improve the process how ocean data is collected and managed. A central element in this development is the suite of Sensor Web Enablement (SWE) standards specified by the Open Geospatial Consortium (OGC). This framework of standards comprises on the one hand data models as well as formats for measurement data (ISO/OGC Observations and Measurement, O&M) and metadata describing measurement processes and sensors (OGC Sensor Model Language, SensorML). On the other hand the SWE standards comprise (Web service) interface specifications for pull-based access to observation data (OGC Sensor Observation Service, SOS) and for controlling or configuring sensors (OGC Sensor Planning Service, SPS). Also within the European INSPIRE framework the SWE standards play an important role as the SOS is the recommended download service interface for O&M-encoded observation data sets. In the context of the EU-funded Oceans of Tomorrow initiative the NeXOS (Next generation, Cost-effective, Compact, Multifunctional Web Enabled Ocean Sensor Systems Empowering Marine, Maritime and Fisheries Management) project is developing a new generation of in-situ sensors that make use of the SWE standards to facilitate the data publication process and the integration into Web based information infrastructures. This includes the development of a dedicated firmware for instruments and sensor platforms (SEISI, Smart Electronic Interface for Sensors and Instruments) maintained by the Universitat Politècnica de Catalunya (UPC). Among other features, SEISI makes use of OGC SWE standards such OGC-PUCK, to enable a plug-and-play mechanism for sensors based on SensorML encoded metadata. Thus, if a new instrument is attached to a SEISI-based platform, it automatically configures the connection to these instruments, automatically generated data files compliant with the ISO/OGC Observations and Measurements standard and initiates the data transmission into the NeXOS Sensor Web infrastructure. Besides these platform-related developments, NeXOS has realised the full path of data transmission from the sensor to the end user application. The conceptual architecture design is implemented by a series of open source SWE software packages provided by 52°North. This comprises especially different SWE server components (i.e. OGC Sensor Observation Service), tools for data visualisation (e.g. the 52°North Helgoland SOS viewer), and an editor for providing SensorML-based metadata (52°North smle). As a result, NeXOS has demonstrated how the SWE standards help to improve marine observation data collection. Within this presentation, we will present the experiences and findings of the NeXOS project and will provide recommendation for future work directions.

Community And Stakeholder Engagement With A University-Based Storm Research Team And Program During Events: Progressive Awareness, Cooperation And Mutual Support.

NASA Astrophysics Data System (ADS)

Gayes, P. T.; Bao, S.; Yan, T.; Pietrafesa, L. J.; Hallstrom, J.; Stirling, D.; Mullikin, T.; McClam, M.; Byrd, M.; Aucoin, K.; Marosites, B.

2017-12-01

HUGO: The HUrricane Genesis and Outlook program is a research initiative spanning new approaches to Atlantic tropical season outlooking to a storm event-related interactively coupled model system. In addition to supporting faculty and student academic research it has progressively been engaged by diverse regional interests in the public and private sector. The seasonal outlook incorporates 22 regional-to-global climate drivers developed from the historical storm database and has shown good skill related to historical storm seasons within the development of the model as well as the last several years in an outlook capacity. The event scale model is a based upon a fully interactively coupled model system incorporating ocean, atmosphere, wave and surge/flood models. The recent cluster of storms impacting the Southeast US provided an opportunity to test the model system and helped develop strong collaborative interests across diverse groups seeking to facilitate local capacity and access to additional storm-related information, observations and expertise. The SC State Guard has actively engaged the HUGO team in carrying out their charge in emergency responders planning and activities during several recent storms and flooding events. They were instrumental in developing support to expand observational systems aiding model validation and development as well as develop access pathways for deployment of new observational technology developed through NSF sponsored projects (Intelligent River and Hurricane-RAPID) with ISENSE at Florida Atlantic University to advance observational capability and density especially during or immediately following events. At the same time an increasing number of county-level emergency and environmental managers and private sector interests have similarly been working collaborately towards expanding observational systems contributing to the goals of the growing storm-oriented cooperative and as well as broader national MesoUS goals. Collectively, the interaction and partnering have aided and advanced diverse interests, enabled direct and in-kind support towards mutual goals and enabled considerable leverage of resources focused on science and supporting applications.

Direct Imaging of the Nearest Planetary Systems with NASA's WFIRST Mission

NASA Astrophysics Data System (ADS)

Turnbull, M. C.; Macintosh, B.; Kasdin, J.; Seager, S.; Roberge, A.; Marley, M.; Mandell, A.; Lupu, R.; Hildebrandt, S.; Lewis, N.; Shaklan, S.; Stark, C.

2017-11-01

Using the Coronagraph Instrument (CGI), WFIRST will enable our generation, for the first time in human history, to directly image and characterize planets similar to those in our solar system. We will review the purpose and status of the mission.

Plenoptic imaging with second-order correlations of light

NASA Astrophysics Data System (ADS)

Pepe, Francesco V.; Scarcelli, Giuliano; Garuccio, Augusto; D'Angelo, Milena

2016-01-01

Plenoptic imaging is a promising optical modality that simultaneously captures the location and the propagation direction of light in order to enable tridimensional imaging in a single shot. We demonstrate that it is possible to implement plenoptic imaging through second-order correlations of chaotic light, thus enabling to overcome the typical limitations of classical plenoptic devices.

Structural geologic interpretations from radar imagery

USGS Publications Warehouse

Reeves, Robert G.

1969-01-01

Certain structural geologic features may be more readily recognized on sidelooking airborne radar (SLAR) images than on conventional aerial photographs, other remote sensor imagery, or by ground observations. SLAR systems look obliquely to one or both sides and their images resemble aerial photographs taken at low sun angle with the sun directly behind the camera. They differ from air photos in geometry, resolution, and information content. Radar operates at much lower frequencies than the human eye, camera, or infrared sensors, and thus "sees" differently. The lower frequency enables it to penetrate most clouds and some precipitation, haze, dust, and some vegetation. Radar provides its own illumination, which can be closely controlled in intensity and frequency. It is narrow band, or essentially monochromatic. Low relief and subdued features are accentuated when viewed from the proper direction. Runs over the same area in significantly different directions (more than 45° from each other), show that images taken in one direction may emphasize features that are not emphasized on those taken in the other direction; optimum direction is determined by those features which need to be emphasized for study purposes. Lineaments interpreted as faults stand out on radar imagery of central and western Nevada; folded sedimentary rocks cut by faults can be clearly seen on radar imagery of northern Alabama. In these areas, certain structural and stratigraphic features are more pronounced on radar images than on conventional photographs; thus radar imagery materially aids structural interpretation.

Exploring the initial steps of the testing process: frequency and nature of pre-preanalytic errors.

PubMed

Carraro, Paolo; Zago, Tatiana; Plebani, Mario

2012-03-01

Few data are available on the nature of errors in the so-called pre-preanalytic phase, the initial steps of the testing process. We therefore sought to evaluate pre-preanalytic errors using a study design that enabled us to observe the initial procedures performed in the ward, from the physician's test request to the delivery of specimens in the clinical laboratory. After a 1-week direct observational phase designed to identify the operating procedures followed in 3 clinical wards, we recorded all nonconformities and errors occurring over a 6-month period. Overall, the study considered 8547 test requests, for which 15 917 blood sample tubes were collected and 52 982 tests undertaken. No significant differences in error rates were found between the observational phase and the overall study period, but underfilling of coagulation tubes was found to occur more frequently in the direct observational phase (P = 0.043). In the overall study period, the frequency of errors was found to be particularly high regarding order transmission [29 916 parts per million (ppm)] and hemolysed samples (2537 ppm). The frequency of patient misidentification was 352 ppm, and the most frequent nonconformities were test requests recorded in the diary without the patient's name and failure to check the patient's identity at the time of blood draw. The data collected in our study confirm the relative frequency of pre-preanalytic errors and underline the need to consensually prepare and adopt effective standard operating procedures in the initial steps of laboratory testing and to monitor compliance with these procedures over time.

Observation of unidirectional backscattering-immune topological electromagnetic states.

PubMed

Wang, Zheng; Chong, Yidong; Joannopoulos, J D; Soljacić, Marin

2009-10-08

One of the most striking phenomena in condensed-matter physics is the quantum Hall effect, which arises in two-dimensional electron systems subject to a large magnetic field applied perpendicular to the plane in which the electrons reside. In such circumstances, current is carried by electrons along the edges of the system, in so-called chiral edge states (CESs). These are states that, as a consequence of nontrivial topological properties of the bulk electronic band structure, have a unique directionality and are robust against scattering from disorder. Recently, it was theoretically predicted that electromagnetic analogues of such electronic edge states could be observed in photonic crystals, which are materials having refractive-index variations with a periodicity comparable to the wavelength of the light passing through them. Here we report the experimental realization and observation of such electromagnetic CESs in a magneto-optical photonic crystal fabricated in the microwave regime. We demonstrate that, like their electronic counterparts, electromagnetic CESs can travel in only one direction and are very robust against scattering from disorder; we find that even large metallic scatterers placed in the path of the propagating edge modes do not induce reflections. These modes may enable the production of new classes of electromagnetic device and experiments that would be impossible using conventional reciprocal photonic states alone. Furthermore, our experimental demonstration and study of photonic CESs provides strong support for the generalization and application of topological band theories to classical and bosonic systems, and may lead to the realization and observation of topological phenomena in a generally much more controlled and customizable fashion than is typically possible with electronic systems.

Identification of the Infrared Counterpart of SGR 1935+2154 with the Hubble Space Telescope

NASA Astrophysics Data System (ADS)

Levan, Andrew; Kouveliotou, Chryssa; Fruchter, Andrew

2018-02-01

We present deep Hubble Space Telescope observations of a new magnetar source, the soft gamma-repeater SGR 1935+2154, discovered by Swift. We obtained three epochs of observations: while the source was active in 2015 March, during a quiescent period in 2015 August, and during a further active phase in 2016 May. Close to the center of the X-ray error region identified by Chandra, we find a faint (F140W(AB) = 25.3) source, which fades by a factor of ∼2 over the course of 5 months between the first two epochs of observations, before rebrightening during the second active period. If this source is indeed the counterpart to SGR 1935+2154, then it is among the faintest yet located for a magnetar. Our observations are spaced over 1.3 years and enable us to place limits on the source velocity of μ = (60 ± 40) km s‑1 kpc‑1 observations on timescales of a decade can hence probe proper motion limits smaller than the velocities observed for the majority of pulsars. The comparison of the optical/IR and X-ray light curves of the source suggests that emission in the two regimes is associated but not directly correlated, offering support for a magnetospheric versus a fallback disk origin.

Aligning Ag Nanowires by a Facile Bioinspired Directional Liquid Transfer: Toward Anisotropic Flexible Conductive Electrodes.

PubMed

Meng, Lili; Bian, Ruixin; Guo, Cheng; Xu, Bojie; Liu, Huan; Jiang, Lei

2018-06-01

Recent years have witnessed the booming development of transparent flexible electrodes (TFEs) for their applications in electronics and optoelectronic devices. Various strategies have thus been developed for preparing TFEs with higher flexibility and conductivity. However, little work has focused on TFEs with anisotropic conductivity. Here, a facile strategy of directional liquid transfer is proposed, guided by a conical fibers array (CFA), based on which silver nanowires (AgNWs) are aligned on a soft poly(ethylene terephthalate) substrate in large scale. After further coating a second thin layer of the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), a TFE with notable anisotropic conductivity and excellent optical transmittance of 95.2% is prepared. It is proposed that the CFA enables fine control over the receding of the three-phase contact line during the dewetting process, where AgNWs are guided and aligned by the as-generated directional stress. Moreover, anisotropic electrochemical deposition is enabled where the Cu nanoparticles deposit only on the oriented AgNWs, leading to a surface with anisotropic wetting behavior. Importantly, the approach enables alignment of AgNWs via multiple directions at one step. It is envisioned that the as-developed approach will provide an optional approach for simple and low-cost preparation of TFE with various functions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.