Bottlenecks of the wavefront sensor based on the Talbot effect.

PubMed

Podanchuk, Dmytro; Kovalenko, Andrey; Kurashov, Vitalij; Kotov, Myhaylo; Goloborodko, Andrey; Danko, Volodymyr

2014-04-01

Physical constraints and peculiarities of the wavefront sensing technique, based on the Talbot effect, are discussed. The limitation on the curvature of the measurable wavefront is derived. The requirements to the Fourier spectrum of the periodic mask are formulated. Two kinds of masks are studied for their performance in the wavefront sensor. It is shown that the boundary part of the mask aperture does not contribute to the initial data for wavefront restoration. It is verified by experiment and computer simulation that the performance of the Talbot sensor, which meets established conditions, is similar to that of the Shack-Hartmann sensor.

46 CFR 7.85 - St. Simons Island, GA to Little Talbot Island, FL.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false St. Simons Island, GA to Little Talbot Island, FL. 7.85... BOUNDARY LINES Atlantic Coast § 7.85 St. Simons Island, GA to Little Talbot Island, FL. (a) A line drawn from latitude 31°04.1′ N. longitude 81°16.7′ W. (St. Simons Lighted Whistle Buoy “ST S”) to latitude 30...

Coherent emission from integrated Talbot-cavity quantum cascade lasers.

PubMed

Meng, Bo; Qiang, Bo; Rodriguez, Etienne; Hu, Xiao Nan; Liang, Guozhen; Wang, Qi Jie

2017-02-20

We report experimental realization of phase-locked quantum cascade laser (QCL) array using a monolithically integrated Talbot cavity. An array with six laser elements at a wavelength of ~4.8 μm shows a maximum peak power of ~4 W which is more than 5 times higher than that of a single ridge laser element and a slope efficiency of 1 W/A at room temperature. Operation of in-phase coherent supermode has been achieved over the whole dynamic range of the Talbot-cavity QCL. The structure was analysed using a straightforward theoretical model, showing quantitatively good agreement with the experimental results. The reduced thermal resistance makes the structure an attractive approach to achieve high beam quality continuous wave QCLs.

Understanding Photography as Applied Chemistry: Using Talbot's Calotype Process to Introduce Chemistry to Design Students

ERIC Educational Resources Information Center

Ro¨sch, Esther S.; Helmerdig, Silke

2017-01-01

Early photography processes were predestined to combine chemistry and art. William Henry Fox Talbot is one of the early photography pioneers. In 2-3 day workshops, design students without a major background in chemistry are able to define a reproducible protocol for Talbot's gallic acid containing calotype process. With the experimental concept…

Observation of electromagnetically induced Talbot effect in an atomic system

NASA Astrophysics Data System (ADS)

Zhang, Zhaoyang; Liu, Xing; Zhang, Dan; Sheng, Jiteng; Zhang, Yiqi; Zhang, Yanpeng; Xiao, Min

2018-01-01

The electromagnetically induced Talbot effect (EITE) resulting from the repeated self-reconstruction of a spatially intensity-modulated probe field is experimentally demonstrated in a three-level atomic configuration. The probe beam is launched into an optically induced lattice (established by the interference of two coupling fields) inside a rubidium vapor cell and is diffracted by the electromagnetically induced grating that was formed. The diffraction pattern repeats itself at the planes of integer multiple Talbot lengths. In addition, a fractional EITE is also investigated. The experimental observations agree well with the theoretical predictions. This investigation may potentially pave the way for studying the nonlinear and quantum dynamical features that have been predicted for established periodic optical systems.

A preclinical Talbot-Lau prototype for x-ray dark-field imaging of human-sized objects.

PubMed

Hauke, C; Bartl, P; Leghissa, M; Ritschl, L; Sutter, S M; Weber, T; Zeidler, J; Freudenberger, J; Mertelmeier, T; Radicke, M; Michel, T; Anton, G; Meinel, F G; Baehr, A; Auweter, S; Bondesson, D; Gaass, T; Dinkel, J; Reiser, M; Hellbach, K

2018-06-01

Talbot-Lau x-ray interferometry provides information about the scattering and refractive properties of an object - in addition to the object's attenuation features. Until recently, this method was ineligible for imaging human-sized objects as it is challenging to adapt Talbot-Lau interferometers (TLIs) to the relevant x-ray energy ranges. In this work, we present a preclinical Talbot-Lau prototype capable of imaging human-sized objects with proper image quality at clinically acceptable dose levels. The TLI is designed to match a setup of clinical relevance as closely as possible. The system provides a scan range of 120 × 30 cm 2 by using a scanning beam geometry. Its ultimate load is 100 kg. High aspect ratios and fine grid periods of the gratings ensure a reasonable setup length and clinically relevant image quality. The system is installed in a university hospital and is, therefore, exposed to the external influences of a clinical environment. To demonstrate the system's capabilities, a full-body scan of a euthanized pig was performed. In addition, freshly excised porcine lungs with an extrinsically provoked pneumothorax were mounted into a human thorax phantom and examined with the prototype. Both examination sequences resulted in clinically relevant image quality - even in the case of a skin entrance air kerma of only 0.3 mGy which is in the range of human thoracic imaging. The presented case of a pneumothorax and a reader study showed that the prototype's dark-field images provide added value for pulmonary diagnosis. We demonstrated that a dedicated design of a Talbot-Lau interferometer can be applied to medical imaging by constructing a preclinical Talbot-Lau prototype. We experienced that the system is feasible for imaging human-sized objects and the phase-stepping approach is suitable for clinical practice. Hence, we conclude that Talbot-Lau x-ray imaging has potential for clinical use and enhances the diagnostic power of medical x-ray imaging. �

Single-shot digital holography by use of the fractional Talbot effect.

PubMed

Martínez-León, Lluís; Araiza-E, María; Javidi, Bahram; Andrés, Pedro; Climent, Vicent; Lancis, Jesús; Tajahuerce, Enrique

2009-07-20

We present a method for recording in-line single-shot digital holograms based on the fractional Talbot effect. In our system, an image sensor records the interference between the light field scattered by the object and a properly codified parallel reference beam. A simple binary two-dimensional periodic grating is used to codify the reference beam generating a periodic three-step phase distribution over the sensor plane by fractional Talbot effect. This provides a method to perform single-shot phase-shifting interferometry at frame rates only limited by the sensor capabilities. Our technique is well adapted for dynamic wavefront sensing applications. Images of the object are digitally reconstructed from the digital hologram. Both computer simulations and experimental results are presented.

Free space and waveguide Talbot effect: phase relations and planar light circuit applications

NASA Astrophysics Data System (ADS)

Nikkhah, H.; Zheng, Q.; Hasan, I.; Abdul-Majid, S.; Hall, T. J.

2012-10-01

Optical fields that are periodic in the transverse plane self-image periodically as they propagate along the optical axis: a phenomenon known as the Talbot effect. A transfer matrix may be defined that relates the amplitude and phase of point sources placed on a particular grid at the input to their respective multiple images at an image plane. The free-space Talbot effect may be mapped to the waveguide Talbot effect. Applying this mapping to the transfer matrix enables the prediction of the phase and amplitude relations between the ports of a Multimode Interference (MMI) coupler- a planar waveguide device. The transfer matrix approach has not previously been applied to the free-space case and its mapping to the waveguide case provides greater clarity and physical insight into the phase relationships than previous treatments. The paper first introduces the underlying physics of the Talbot effect in free space with emphasis on the positions along the optical axis at which images occur; their multiplicity; and their relative phase relations determined by the Gauss Quadratic Sum of number theory. The analysis is then adapted to predict the phase relationships between the ports of an MMI. These phase relationships are critical to planar light circuit (PLC) applications such as 90° optical hybrids for coherent optical receiver front-ends, external optical I-Q modulators for coherent optical transmitters; and optical phased array switches. These applications are illustrated by results obtained from devices that have been fabricated and tested by the PTLab in Si micro-photonic integration platforms.

Quantum information processing by weaving quantum Talbot carpets

NASA Astrophysics Data System (ADS)

Farías, Osvaldo Jiménez; de Melo, Fernando; Milman, Pérola; Walborn, Stephen P.

2015-06-01

Single-photon interference due to passage through a periodic grating is considered in a novel proposal for processing D -dimensional quantum systems (quDits) encoded in the spatial degrees of freedom of light. We show that free-space propagation naturally implements basic single-quDit gates by means of the Talbot effect: an intricate time-space carpet of light in the near-field diffraction regime. By adding a diagonal phase gate, we show that a complete set of single-quDit gates can be implemented. We then introduce a spatially dependent beam splitter that allows for projective measurements in the computational basis and can be used for the implementation of controlled operations between two quDits. Universal quantum information processing can then be implemented with linear optics and ancilla photons via postselection and feed-forward following the original proposal of Knill-Laflamme and Milburn. Although we consider photons, our scheme should be directly applicable to a number of other physical systems. Interpretation of the Talbot effect as a quantum logic operation provides a beautiful and interesting way to visualize quantum computation through wave propagation and interference.

Self-Focusing and the Talbot Effect in Conformal Transformation Optics.

PubMed

Wang, Xiangyang; Chen, Huanyang; Liu, Hui; Xu, Lin; Sheng, Chong; Zhu, Shining

2017-07-21

Transformation optics has been used to propose various novel optical devices. With the help of metamaterials, several intriguing designs, such as invisibility cloaks, have been implemented. However, as the basic units should be much smaller than the working wavelengths to achieve the effective material parameters, and the sizes of devices should be much larger than the wavelengths of illumination to work within the light-ray approximation, it is a big challenge to implement an experimental system that works simultaneously for both geometric optics and wave optics. In this Letter, by using a gradient-index microstructured optical waveguide, we realize a device of conformal transformation optics (CTO) and demonstrate its self-focusing property for geometry optics and the Talbot effect for wave optics. In addition, the Talbot effect in such a system has a potential application to transfer digital information without diffraction. Our findings demonstrate the photon controlling ability of CTO in a feasible experiment system.

Self-Focusing and the Talbot Effect in Conformal Transformation Optics

NASA Astrophysics Data System (ADS)

Wang, Xiangyang; Chen, Huanyang; Liu, Hui; Xu, Lin; Sheng, Chong; Zhu, Shining

2017-07-01

Transformation optics has been used to propose various novel optical devices. With the help of metamaterials, several intriguing designs, such as invisibility cloaks, have been implemented. However, as the basic units should be much smaller than the working wavelengths to achieve the effective material parameters, and the sizes of devices should be much larger than the wavelengths of illumination to work within the light-ray approximation, it is a big challenge to implement an experimental system that works simultaneously for both geometric optics and wave optics. In this Letter, by using a gradient-index microstructured optical waveguide, we realize a device of conformal transformation optics (CTO) and demonstrate its self-focusing property for geometry optics and the Talbot effect for wave optics. In addition, the Talbot effect in such a system has a potential application to transfer digital information without diffraction. Our findings demonstrate the photon controlling ability of CTO in a feasible experiment system.

Quasi-Talbot effect of orbital angular momentum beams for generation of optical vortex arrays by multiplexing metasurface design.

PubMed

Gao, Hui; Li, Yang; Chen, Lianwei; Jin, Jinjin; Pu, Mingbo; Li, Xiong; Gao, Ping; Wang, Changtao; Luo, Xiangang; Hong, Minghui

2018-01-03

The quasi-Talbot effect of orbital angular momentum (OAM) beams, in which the centers are placed in a rotationally symmetric position, is demonstrated both numerically and experimentally for the first time. Since its multiplication factor is much higher than the conventional fractional Talbot effect, the quasi-Talbot effect can be used in the generation of vortex beam arrays. A metasurface based on this theory was designed and fabricated to test the validity of this assumption. The agreement between the numerical and measured results suggests the practicability of this method to realize vortex beam arrays with high integrated levels, which can open a new door to achieve various potential uses related to optical vortex arrays in integrated optical systems for wide-ranging applications.

High resolution Talbot self-imaging applied to structural characterization of self-assembled monolayers of microspheres.

PubMed

Garcia-Sucerquia, J; Alvarez-Palacio, D C; Kreuzer, H J

2008-09-10

We report the observation of the Talbot self-imaging effect in high resolution digital in-line holographic microscopy (DIHM) and its application to structural characterization of periodic samples. Holograms of self-assembled monolayers of micron-sized polystyrene spheres are reconstructed at different image planes. The point-source method of DIHM and the consequent high lateral resolution allows the true image (object) plane to be identified. The Talbot effect is then exploited to improve the evaluation of the pitch of the assembly and to examine defects in its periodicity.

Laser Surface Microstructuring of Biocompatible Materials Using a Microlens Array and the Talbot Effect: Evaluation of the Cell Adhesion.

PubMed

Aymerich, María; Nieto, Daniel; Álvarez, Ezequiel; Flores-Arias, María T

2017-02-22

A laser based technique for microstructuring titanium and tantalum substrates using the Talbot effect and an array of microlenses is presented. By using this hybrid technique; we are able to generate different patterns and geometries on the top surfaces of the biomaterials. The Talbot effect allows us to rapidly make microstructuring, solving the common problems of using microlenses for multipatterning; where the material expelled during the ablation of biomaterials damages the microlens. The Talbot effect permits us to increase the working distance and reduce the period of the patterns. We also demonstrate that the geometries and patterns act as anchor points for cells; affecting the cell adhesion to the metallic substrates and guiding how they spread over the material.

Laser Surface Microstructuring of Biocompatible Materials Using a Microlens Array and the Talbot Effect: Evaluation of the Cell Adhesion

PubMed Central

Aymerich, María; Nieto, Daniel; Álvarez, Ezequiel; Flores-Arias, María T.

2017-01-01

A laser based technique for microstructuring titanium and tantalum substrates using the Talbot effect and an array of microlenses is presented. By using this hybrid technique; we are able to generate different patterns and geometries on the top surfaces of the biomaterials. The Talbot effect allows us to rapidly make microstructuring, solving the common problems of using microlenses for multipatterning; where the material expelled during the ablation of biomaterials damages the microlens. The Talbot effect permits us to increase the working distance and reduce the period of the patterns. We also demonstrate that the geometries and patterns act as anchor points for cells; affecting the cell adhesion to the metallic substrates and guiding how they spread over the material. PMID:28772574

Experimental research on the feature of an x-ray Talbot-Lau interferometer versus tube accelerating voltage

NASA Astrophysics Data System (ADS)

Wang, Sheng-Hao; Margie, P. Olbinado; Atsushi, Momose; Hua-Jie, Han; Hu, Ren-Fang; Wang, Zhi-Li; Gao, Kun; Zhang, Kai; Zhu, Pei-Ping; Wu, Zi-Yu

2015-06-01

X-ray Talbot-Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a conventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of samples producing low absorption contrast, thus bearing tremendous potential for future clinical diagnosis. In this work, by changing the accelerating voltage of the x-ray tube from 35 kV to 45 kV, x-ray phase-contrast imaging of a test sample is performed at each integer value of the accelerating voltage to investigate the characteristic of an x-ray Talbot-Lau interferometer (located in the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan) versus tube voltage. Experimental results and data analysis show that within a range this x-ray Talbot-Lau interferometer is not sensitive to the accelerating voltage of the tube with a constant fringe visibility of ˜ 44%. This x-ray Talbot-Lau interferometer research demonstrates the feasibility of a new dual energy phase-contrast x-ray imaging strategy and the possibility to collect a refraction spectrum. Project supported by the Major State Basic Research Development Program of China (Grant No. 2012CB825800), the Science Fund for Creative Research Groups, China (Grant No. 11321503), the National Natural Science Foundation of China (Grant Nos. 11179004, 10979055, 11205189, and 11205157), and the Japan-Asia Youth Exchange Program in Science (SAKURA Exchange Program in Science) Administered by the Japan Science and Technology Agency.

Talbot effect of the defective grating in deep Fresnel region

NASA Astrophysics Data System (ADS)

Teng, Shuyun; Wang, Junhong; Zhang, Wei; Cui, Yuwei

2015-02-01

Talbot effect of the grating with different defect is studied theoretically and experimentally in this paper. The defects of grating include the loss of the diffraction unit, the dislocation of the diffraction unit and the modulation of the unit separation. The exact diffraction distributions of three kinds of defective gratings are obtained according to the finite-difference time-domain (FDTD) method. The calculation results show the image of the missing or dislocating unit appears at the Talbot distance (as mentioned in K. Patorski Prog. Opt., 27, 1989, pp.1-108). This is the so-called self-repair ability of grating imaging. In addition, some more phenomena are discovered. The loss or the dislocation of diffraction unit causes the diffraction distortion within a certain radial angle. The regular modulation of unit separation changes the original diffraction, but the new periodicity of the diffraction distribution rebuilds. The self-imaging of grating with smaller random modulation still keeps the partial self-repair ability, and yet this characteristic depends on the modulation degree of defective grating. These diffraction phenomena of the defective gratings are explained by use of the diffraction theory of grating. The practical experiment is also performed and the experimental results confirm the theoretic predictions.

Onion cell imaging by using Talbot/self-imaging effect

NASA Astrophysics Data System (ADS)

Agarwal, Shilpi; Kumar, Varun; Shakher, Chandra

2017-08-01

This paper presents the amplitude and phase imaging of onion epidermis cell using the self-imaging capabilities of a grating (Talbot effect) in visible light region. In proposed method, the Fresnel diffraction pattern from the first grating and object is recorded at self-image plane. Fast Fourier Transform (FFT) is used for extracting the 3D amplitude and phase image of onion epidermis cell. The stability of the proposed system, from environmental perturbation as well as its compactness and portability give the proposed system a high potential for several clinical applications.

Nonlinear Talbot effect of rogue waves.

PubMed

Zhang, Yiqi; Belić, Milivoj R; Zheng, Huaibin; Chen, Haixia; Li, Changbiao; Song, Jianping; Zhang, Yanpeng

2014-03-01

Akhmediev and Kuznetsov-Ma breathers are rogue wave solutions of the nonlinear Schrödinger equation (NLSE). Talbot effect (TE) is an image recurrence phenomenon in the diffraction of light waves. We report the nonlinear TE of rogue waves in a cubic medium. It is different from the linear TE, in that the wave propagates in a NL medium and is an eigenmode of NLSE. Periodic rogue waves impinging on a NL medium exhibit recurrent behavior, but only at the TE length and at the half-TE length with a π-phase shift; the fractional TE is absent. The NL TE is the result of the NL interference of the lobes of rogue wave breathers. This interaction is related to the transverse period and intensity of breathers, in that the bigger the period and the higher the intensity, the shorter the TE length.

Wavefront sensor based on the Talbot effect with the precorrected holographic grating.

PubMed

Podanchuk, Dmytro; Kurashov, Vitalij; Goloborodko, Andrey; Dan'ko, Volodymyr; Kotov, Myhaylo; Goloborodko, Natalya

2012-04-01

A holographic wavefront sensor based on the Talbot effect is proposed. Optical wavefronts are measured by sampling the light amplitude distribution with a two-dimensional (2D) precorrected holographic grating. The factors that allow changing an angular measurement range and a spatial resolution of the sensor are discussed. A comparative analysis with the Shack-Hartmann sensor is illustrated with some experimental results.

Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

DOE PAGES

Liu, Bo; Braiman, Yehuda

2018-02-06

In this paper, we introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ~25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. Finally, we found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

NASA Astrophysics Data System (ADS)

Liu, Bo; Braiman, Yehuda

2018-05-01

We introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ∼25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. We found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

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

Liu, Bo; Braiman, Yehuda

In this paper, we introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ~25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. Finally, we found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

Talbot-Lau X-ray Deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments

DOE PAGES

Valdivia, M. P.; Stutman, D.; Stoeckl, C.; ...

2016-04-21

Talbot-Lau X-ray Deflectometry has been developed as an electron density diagnostic for High Energy Density plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping was demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moire pattern formation and grating survival was also observed using a copper x-pinch driven at 400 kA, ~1 kA/ns. Lastly, these results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Adaptive wavefront sensor based on the Talbot phenomenon.

PubMed

Podanchuk, Dmytro V; Goloborodko, Andrey A; Kotov, Myhailo M; Kovalenko, Andrey V; Kurashov, Vitalij N; Dan'ko, Volodymyr P

2016-04-20

A new adaptive method of wavefront sensing is proposed and demonstrated. The method is based on the Talbot self-imaging effect, which is observed in an illuminating light beam with strong second-order aberration. Compensation of defocus and astigmatism is achieved with an appropriate choice of size of the rectangular unit cell of the diffraction grating, which is performed iteratively. A liquid-crystal spatial light modulator is used for this purpose. Self-imaging of rectangular grating in the astigmatic light beam is demonstrated experimentally. High-order aberrations are detected with respect to the compensated second-order aberration. The comparative results of wavefront sensing with a Shack-Hartmann sensor and the proposed sensor are adduced.

High-energy x-ray Talbot-Lau radiography of a human knee

NASA Astrophysics Data System (ADS)

Horn, F.; Gelse, K.; Jabari, S.; Hauke, C.; Kaeppler, S.; Ludwig, V.; Meyer, P.; Michel, T.; Mohr, J.; Pelzer, G.; Rieger, J.; Riess, C.; Seifert, M.; Anton, G.

2017-08-01

We report on a radiographic measurement of an ex vivo human knee using a grating-based phase-contrast imaging setup and a medical x-ray tube at a tube voltage of 70 kV. The measurement has been carried out using a Talbot-Lau setup that is suitable to achieve a high visibility in the energy regime of medical imaging. In a medical reading by an experienced trauma surgeon signatures of chondrocalcinosis in the medial meniscus have been identified more evidently using the dark-field image in comparison to the conventional attenuation image. The analysis has been carried out at various dose levels down to 0.14 mGy measured as air kerma, which is a dose comparable to clinically used radiographic devices. The diagnosis has been confirmed by a histological analysis of the meniscus tissue. In the introduced high-frequency filtered phase-contrast image the anterior and posterior horn of the medial meniscus and the posterior cruciate ligament have also been visible. Furthermore, atherosclerotic plaque is visible in both imaging modalities, attenuation and dark-field, despite the presence of overlaying bone. This measurement, for the first time, proves the feasibility of Talbot-Lau x-ray imaging at high-energy spectra above 40 kVp and reasonable dose levels with regard to spacious and dense objects.

Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited)

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

Valdivia, M. P., E-mail: mpvaldivia@pha.jhu.edu; Stutman, D.; Stoeckl, C.

2016-11-15

Talbot-Lau X-ray deflectometry (TXD) has been developed as an electron density diagnostic for High Energy Density (HED) plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping were demonstrated for 25–29 J, 8–30 ps laser pulses using copper foil targets. Moiré pattern formation and grating survival were also observed using a copper x-pinch driven at 400 kA, ∼1 kA/ns. These results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited).

PubMed

Valdivia, M P; Stutman, D; Stoeckl, C; Mileham, C; Begishev, I A; Theobald, W; Bromage, J; Regan, S P; Klein, S R; Muñoz-Cordovez, G; Vescovi, M; Valenzuela-Villaseca, V; Veloso, F

2016-11-01

Talbot-Lau X-ray deflectometry (TXD) has been developed as an electron density diagnostic for High Energy Density (HED) plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping were demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moiré pattern formation and grating survival were also observed using a copper x-pinch driven at 400 kA, ∼1 kA/ns. These results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Moiré deflectometry using the Talbot-Lau interferometer as refraction diagnostic for high energy density plasmas at energies below 10 keV.

PubMed

Valdivia, M P; Stutman, D; Finkenthal, M

2014-07-01

The highly localized density gradients expected in High Energy Density (HED) plasma experiments can be characterized by x-ray phase-contrast imaging in addition to conventional attenuation radiography. Moiré deflectometry using the Talbot-Lau grating interferometer setup is an attractive HED diagnostic due to its high sensitivity to refraction induced phase shifts. We report on the adaptation of such a system for operation in the sub-10 keV range by using a combination of free standing and ultrathin Talbot gratings. This new x-ray energy explored matches well the current x-ray backlighters used for HED experiments, while also enhancing phase effects at lower electron densities. We studied the performance of the high magnification, low energy Talbot-Lau interferometer, for single image phase retrieval using Moiré fringe deflectometry. Our laboratory and simulation studies indicate that such a device is able to retrieve object electron densities from phase shift measurements. Using laboratory x-ray sources from 7 to 15 μm size we obtained accurate simultaneous measurements of refraction and attenuation for both sharp and mild electron density gradients.

The second-order differential phase contrast and its retrieval for imaging with x-ray Talbot interferometry.

PubMed

Yang, Yi; Tang, Xiangyang

2012-12-01

The x-ray differential phase contrast imaging implemented with the Talbot interferometry has recently been reported to be capable of providing tomographic images corresponding to attenuation-contrast, phase-contrast, and dark-field contrast, simultaneously, from a single set of projection data. The authors believe that, along with small-angle x-ray scattering, the second-order phase derivative Φ(") (s)(x) plays a role in the generation of dark-field contrast. In this paper, the authors derive the analytic formulae to characterize the contribution made by the second-order phase derivative to the dark-field contrast (namely, second-order differential phase contrast) and validate them via computer simulation study. By proposing a practical retrieval method, the authors investigate the potential of second-order differential phase contrast imaging for extensive applications. The theoretical derivation starts at assuming that the refractive index decrement of an object can be decomposed into δ = δ(s) + δ(f), where δ(f) corresponds to the object's fine structures and manifests itself in the dark-field contrast via small-angle scattering. Based on the paraxial Fresnel-Kirchhoff theory, the analytic formulae to characterize the contribution made by δ(s), which corresponds to the object's smooth structures, to the dark-field contrast are derived. Through computer simulation with specially designed numerical phantoms, an x-ray differential phase contrast imaging system implemented with the Talbot interferometry is utilized to evaluate and validate the derived formulae. The same imaging system is also utilized to evaluate and verify the capability of the proposed method to retrieve the second-order differential phase contrast for imaging, as well as its robustness over the dimension of detector cell and the number of steps in grating shifting. Both analytic formulae and computer simulations show that, in addition to small-angle scattering, the contrast generated by the

Development of grating-based x-ray Talbot interferometry at the advanced photon source

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

Marathe, Shashidhara; Xiao Xianghui; Wojcik, Michael J.

2012-07-31

We report on the ongoing effort to develop hard x-ray Talbot interferometry at the Advanced Photon Source (APS), Argonne National Laboratory, USA. We describe the design of the interferometer and preliminary results obtained at 25 keV using a feather and a phantom sample lithographically fabricated of gold. We mention the future developmental goals and applications of this technique as a metrology tool for x-ray optics and beam wavefront characterization.

Moiré deflectometry using the Talbot-Lau interferometer as refraction diagnostic for High Energy Density plasmas at energies below 10 keV

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

Valdivia, M. P.; Stutman, D.; Finkenthal, M.

2014-07-15

The highly localized density gradients expected in High Energy Density (HED) plasma experiments can be characterized by x-ray phase-contrast imaging in addition to conventional attenuation radiography. Moiré deflectometry using the Talbot-Lau grating interferometer setup is an attractive HED diagnostic due to its high sensitivity to refraction induced phase shifts. We report on the adaptation of such a system for operation in the sub-10 keV range by using a combination of free standing and ultrathin Talbot gratings. This new x-ray energy explored matches well the current x-ray backlighters used for HED experiments, while also enhancing phase effects at lower electron densities.more » We studied the performance of the high magnification, low energy Talbot-Lau interferometer, for single image phase retrieval using Moiré fringe deflectometry. Our laboratory and simulation studies indicate that such a device is able to retrieve object electron densities from phase shift measurements. Using laboratory x-ray sources from 7 to 15 μm size we obtained accurate simultaneous measurements of refraction and attenuation for both sharp and mild electron density gradients.« less

Pulse repetition rate multiplication by Talbot effect in a coaxial fiber

NASA Astrophysics Data System (ADS)

Dhingra, Nikhil; Saxena, Geetika Jain; Anand, Jyoti; Sharma, Enakshi K.

2018-03-01

We use a coaxial fiber, which is a cylindrical coupled waveguide structure consisting of two concentric cores, the inner rod and an outer ring core as a first order dispersive media to achieve temporal Talbot effect for pulse repetition rate multiplication (PRRM) in high bit rate optical fiber communication. It is observed that for an input Gaussian pulse train with pulse width, 2τ0=1ps at a repetition rate of 40 Gbps (repetition period, T=25ps), an output repetition rate of 640 Gbps can be achieved without significant distortion at a length of 40.92 m.

Towards simultaneous Talbot bands based optical coherence tomography and scanning laser ophthalmoscopy imaging.

PubMed

Marques, Manuel J; Bradu, Adrian; Podoleanu, Adrian Gh

2014-05-01

We report a Talbot bands-based optical coherence tomography (OCT) system capable of producing longitudinal B-scan OCT images and en-face scanning laser ophthalmoscopy (SLO) images of the human retina in-vivo. The OCT channel employs a broadband optical source and a spectrometer. A gap is created between the sample and reference beams while on their way towards the spectrometer's dispersive element to create Talbot bands. The spatial separation of the two beams facilitates collection by an SLO channel of optical power originating exclusively from the retina, deprived from any contribution from the reference beam. Three different modes of operation are presented, constrained by the minimum integration time of the camera used in the spectrometer and by the galvo-scanners' scanning rate: (i) a simultaneous acquisition mode over the two channels, useful for small size imaging, that conserves the pixel-to-pixel correspondence between them; (ii) a hybrid sequential mode, where the system switches itself between the two regimes and (iii) a sequential "on-demand" mode, where the system can be used in either OCT or SLO regimes for as long as required. The two sequential modes present varying degrees of trade-off between pixel-to-pixel correspondence and independent full control of parameters within each channel. Images of the optic nerve and fovea regions obtained in the simultaneous (i) and in the hybrid sequential mode (ii) are presented.

PHOTO DATE: 08-10-15.LOCATION: Bldg. 30 - FCR-1 (30M/231).SUBJECT: Expedition 44, Kjell Lindgren.Kimiya Yui AND SCOTT KELLY TASTING SPACE LETTUCE EXPERIMENT.PHOTOGRAPHER: BILL STAFFORD

NASA Image and Video Library

2015-08-10

JSC2015E076004 (08/10/2015) --- Flight controllers in the International Space Station Mission Control at the Johnson Space Center monitor systems aboard the orbiting laboratory during a number of dynamic events for Expedition 44. Screens in the front of the room show the camera views from two spacewalking Russian cosmonauts while NASA astronaut Kjell Lindgren is seen harvesting lettuce from the Veggie experiment that would become the first food grown in space to be eaten. NASA Photographer Bill Stafford.

Single-Grating Talbot Imaging for Wavefront Sensing and X-Ray Metrology

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

Grizolli, Walan; Shi, Xianbo; Kolodziej, Tomasz

2017-01-01

Single-grating Talbot imaging relies on high-spatial-resolution detectors to perform accurate measurements of X-ray beam wavefronts. The wavefront can be retrieved with a single image, and a typical measurement and data analysis can be performed in few seconds. These qualities make it an ideal tool for synchrotron beamline diagnostics and in-situ metrology. The wavefront measurement can be used both to obtain a phase contrast image of an object and to characterize an X-ray beam. In this work, we explore the concept in two cases: at-wavelength metrology of 2D parabolic beryllium lenses and a wavefront sensor using a diamond crystal beam splitter.

Stopping time: Henry Fox Talbot and the origins of freeze-frame photography.

PubMed

Ramalingam, Chitra

2008-09-01

As an image-making tool for scientists studying the transient, instantaneous photography has long been seen as opening up a visual realm previously inaccessible to the inferior testimony of the human eye. But when photographic pioneer Henry Fox Talbot took the first photograph of a moving object by the light of an electric spark in 1851, he was guided by existing visual practices designed to create instantaneous vision in the eye itself. Exploring the background behind the peculiar subject of his experiment - a mechanically spinning disc - reveals a hidden prehistory of spark-illuminated photography: physicists' pre-photographic techniques for stopping time.

Towards simultaneous Talbot bands based optical coherence tomography and scanning laser ophthalmoscopy imaging

PubMed Central

Marques, Manuel J.; Bradu, Adrian; Podoleanu, Adrian Gh.

2014-01-01

We report a Talbot bands-based optical coherence tomography (OCT) system capable of producing longitudinal B-scan OCT images and en-face scanning laser ophthalmoscopy (SLO) images of the human retina in-vivo. The OCT channel employs a broadband optical source and a spectrometer. A gap is created between the sample and reference beams while on their way towards the spectrometer’s dispersive element to create Talbot bands. The spatial separation of the two beams facilitates collection by an SLO channel of optical power originating exclusively from the retina, deprived from any contribution from the reference beam. Three different modes of operation are presented, constrained by the minimum integration time of the camera used in the spectrometer and by the galvo-scanners’ scanning rate: (i) a simultaneous acquisition mode over the two channels, useful for small size imaging, that conserves the pixel-to-pixel correspondence between them; (ii) a hybrid sequential mode, where the system switches itself between the two regimes and (iii) a sequential “on-demand” mode, where the system can be used in either OCT or SLO regimes for as long as required. The two sequential modes present varying degrees of trade-off between pixel-to-pixel correspondence and independent full control of parameters within each channel. Images of the optic nerve and fovea regions obtained in the simultaneous (i) and in the hybrid sequential mode (ii) are presented. PMID:24877006

Combining Gabor and Talbot bands techniques to enhance the sensitivity with depth in Fourier domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Bradu, Adrian; Marques, Manuel J.; Bouchal, Petr; Podoleanu, Adrian Gh.

2013-03-01

The purpose of this study was to show how to favorably mix two e_ects to improve the sensitivity with depth in Fourier domain optical coherence tomography (OCT): Talbot bands (TB) and Gabor-based fusion (GF) technique. TB operation is achieved by directing the two beams, from the object arm and from the reference arm in the OCT interferometer, along parallel separate paths towards the spectrometer. By changing the lateral gap between the two beams in their path towards the spectrometer, the position for the maximum sensitivity versus the optical path difference in the interferometer is adjusted. For five values of the focus position, the gap between the two beams is readjusted to reach maximum sensitivity. Then, similar to the procedure employed in the GF technique, a composite image is formed by edging together the parts of the five images that exhibited maximum brightness. The combined procedure, TB/GF is examined for four different values of the beam diameters of the two beams. Also we demonstrate volumetric FD-OCT images with mirror term attenuation and sensitivity profile shifted towards higher OPD values by applying a Talbot bands configuration.

X-ray phase scanning setup for non-destructive testing using Talbot-Lau interferometer

NASA Astrophysics Data System (ADS)

Bachche, S.; Nonoguchi, M.; Kato, K.; Kageyama, M.; Koike, T.; Kuribayashi, M.; Momose, A.

2016-09-01

X-ray grating interferometry has a great potential for X-ray phase imaging over conventional X-ray absorption imaging which does not provide significant contrast for weakly absorbing objects and soft biological tissues. X-ray Talbot and Talbot-Lau interferometers which are composed of transmission gratings and measure the differential X-ray phase shifts have gained popularity because they operate with polychromatic beams. In X-ray radiography, especially for nondestructive testing in industrial applications, the feasibility of continuous sample scanning is not yet completely revealed. A scanning setup is frequently advantageous when compared to a direct 2D static image acquisition in terms of field of view, exposure time, illuminating radiation, etc. This paper demonstrates an efficient scanning setup for grating-based Xray phase imaging using laboratory-based X-ray source. An apparatus consisting of an X-ray source that emits X-rays vertically, optical gratings and a photon-counting detector was used with which continuously moving objects across the field of view as that of conveyor belt system can be imaged. The imaging performance of phase scanner was tested by scanning a long continuous moving sample at a speed of 5 mm/s and absorption, differential-phase and visibility images were generated by processing non-uniform moire movie with our specially designed phase measurement algorithm. A brief discussion on the feasibility of phase scanner with scanning setup approach including X-ray phase imaging performance is reported. The successful results suggest a breakthrough for scanning objects those are moving continuously on conveyor belt system non-destructively using the scheme of X-ray phase imaging.

Automated collimation testing by determining the statistical correlation coefficient of Talbot self-images.

PubMed

Rana, Santosh; Dhanotia, Jitendra; Bhatia, Vimal; Prakash, Shashi

2018-04-01

In this paper, we propose a simple, fast, and accurate technique for detection of collimation position of an optical beam using the self-imaging phenomenon and correlation analysis. Herrera-Fernandez et al. [J. Opt.18, 075608 (2016)JOOPDB0150-536X10.1088/2040-8978/18/7/075608] proposed an experimental arrangement for collimation testing by comparing the period of two different self-images produced by a single diffraction grating. Following their approach, we propose a testing procedure based on correlation coefficient (CC) for efficient detection of variation in the size and fringe width of the Talbot self-images and thereby the collimation position. When the beam is collimated, the physical properties of the self-images of the grating, such as its size and fringe width, do not vary from one Talbot plane to the other and are identical; the CC is maximum in such a situation. For the de-collimated position, the size and fringe width of the self-images vary, and correspondingly the CC decreases. Hence, the magnitude of CC is a measure of degree of collimation. Using the method, we could set the collimation position to a resolution of 1 μm, which relates to ±0.25   μ    radians in terms of collimation angle (for testing a collimating lens of diameter 46 mm and focal length 300 mm). In contrast to most collimation techniques reported to date, the proposed technique does not require a translation/rotation of the grating, use of complicated phase evaluation algorithms, or an intricate method for determination of period of the grating or its self-images. The technique is fully automated and provides high resolution and precision.

Diffraction-Induced Bidimensional Talbot Self-Imaging with Full Independent Period Control

NASA Astrophysics Data System (ADS)

Guillet de Chatellus, Hugues; Romero Cortés, Luis; Deville, Antonin; Seghilani, Mohamed; Azaña, José

2017-03-01

We predict, formulate, and observe experimentally a generalized version of the Talbot effect that allows one to create diffraction-induced self-images of a periodic two-dimensional (2D) waveform with arbitrary control of the image spatial periods. Through the proposed scheme, the periods of the output self-image are multiples of the input ones by any desired integer or fractional factor, and they can be controlled independently across each of the two wave dimensions. The concept involves conditioning the phase profile of the input periodic wave before free-space diffraction. The wave energy is fundamentally preserved through the self-imaging process, enabling, for instance, the possibility of the passive amplification of the periodic patterns in the wave by a purely diffractive effect, without the use of any active gain.

Diffraction-Induced Bidimensional Talbot Self-Imaging with Full Independent Period Control.

PubMed

Guillet de Chatellus, Hugues; Romero Cortés, Luis; Deville, Antonin; Seghilani, Mohamed; Azaña, José

2017-03-31

We predict, formulate, and observe experimentally a generalized version of the Talbot effect that allows one to create diffraction-induced self-images of a periodic two-dimensional (2D) waveform with arbitrary control of the image spatial periods. Through the proposed scheme, the periods of the output self-image are multiples of the input ones by any desired integer or fractional factor, and they can be controlled independently across each of the two wave dimensions. The concept involves conditioning the phase profile of the input periodic wave before free-space diffraction. The wave energy is fundamentally preserved through the self-imaging process, enabling, for instance, the possibility of the passive amplification of the periodic patterns in the wave by a purely diffractive effect, without the use of any active gain.

Complex dark-field contrast and its retrieval in x-ray phase contrast imaging implemented with Talbot interferometry.

PubMed

Yang, Yi; Tang, Xiangyang

2014-10-01

Under the existing theoretical framework of x-ray phase contrast imaging methods implemented with Talbot interferometry, the dark-field contrast refers to the reduction in interference fringe visibility due to small-angle x-ray scattering of the subpixel microstructures of an object to be imaged. This study investigates how an object's subpixel microstructures can also affect the phase of the intensity oscillations. Instead of assuming that the object's subpixel microstructures distribute in space randomly, the authors' theoretical derivation starts by assuming that an object's attenuation projection and phase shift vary at a characteristic size that is not smaller than the period of analyzer grating G₂ and a characteristic length dc. Based on the paraxial Fresnel-Kirchhoff theory, the analytic formulae to characterize the zeroth- and first-order Fourier coefficients of the x-ray irradiance recorded at each detector cell are derived. Then the concept of complex dark-field contrast is introduced to quantify the influence of the object's microstructures on both the interference fringe visibility and the phase of intensity oscillations. A method based on the phase-attenuation duality that holds for soft tissues and high x-ray energies is proposed to retrieve the imaginary part of the complex dark-field contrast for imaging. Through computer simulation study with a specially designed numerical phantom, they evaluate and validate the derived analytic formulae and the proposed retrieval method. Both theoretical analysis and computer simulation study show that the effect of an object's subpixel microstructures on x-ray phase contrast imaging method implemented with Talbot interferometry can be fully characterized by a complex dark-field contrast. The imaginary part of complex dark-field contrast quantifies the influence of the object's subpixel microstructures on the phase of intensity oscillations. Furthermore, at relatively high energies, for soft tissues it can be

Glancing angle Talbot-Lau grating interferometers for phase contrast imaging at high x-ray energy

NASA Astrophysics Data System (ADS)

Stutman, D.; Finkenthal, M.

2012-08-01

A Talbot-Lau interferometer is demonstrated using micro-periodic gratings inclined at a glancing angle along the light propagation direction. Due to the increase in the effective thickness of the absorption gratings, the device enables differential phase contrast imaging at high x-ray energy, with improved fringe visibility (contrast). For instance, at 28° glancing angle, we obtain up to ˜35% overall interferometer contrast with a spectrum having ˜43 keV mean energy, suitable for medical applications. In addition, glancing angle interferometers could provide high contrast at energies above 100 keV, enabling industrial and security applications of phase contrast imaging.

Measuring finite-range phase coherence in an optical lattice using Talbot interferometry

PubMed Central

Santra, Bodhaditya; Baals, Christian; Labouvie, Ralf; Bhattacherjee, Aranya B.; Pelster, Axel; Ott, Herwig

2017-01-01

One of the important goals of present research is to control and manipulate coherence in a broad variety of systems, such as semiconductor spintronics, biological photosynthetic systems, superconducting qubits and complex atomic networks. Over the past decades, interferometry of atoms and molecules has proven to be a powerful tool to explore coherence. Here we demonstrate a near-field interferometer based on the Talbot effect, which allows us to measure finite-range phase coherence of ultracold atoms in an optical lattice. We apply this interferometer to study the build-up of phase coherence after a quantum quench of a Bose–Einstein condensate residing in a one-dimensional optical lattice. Our technique of measuring finite-range phase coherence is generic, easy to adopt and can be applied in practically all lattice experiments without further modifications. PMID:28580941

Cadaveric and in vivo human joint imaging based on differential phase contrast by X-ray Talbot-Lau interferometry.

PubMed

Tanaka, Junji; Nagashima, Masabumi; Kido, Kazuhiro; Hoshino, Yoshihide; Kiyohara, Junko; Makifuchi, Chiho; Nishino, Satoshi; Nagatsuka, Sumiya; Momose, Atsushi

2013-09-01

We developed an X-ray phase imaging system based on Talbot-Lau interferometry and studied its feasibility for clinical diagnoses of joint diseases. The system consists of three X-ray gratings, a conventional X-ray tube, an object holder, an X-ray image sensor, and a computer for image processing. The joints of human cadavers and healthy volunteers were imaged, and the results indicated sufficient sensitivity to cartilage, suggesting medical significance. Copyright © 2012. Published by Elsevier GmbH.

High precision locating control system based on VCM for Talbot lithography

NASA Astrophysics Data System (ADS)

Yao, Jingwei; Zhao, Lixin; Deng, Qian; Hu, Song

2016-10-01

Aiming at the high precision and efficiency requirements of Z-direction locating in Talbot lithography, a control system based on Voice Coil Motor (VCM) was designed. In this paper, we built a math model of VCM and its moving characteristic was analyzed. A double-closed loop control strategy including position loop and current loop were accomplished. The current loop was implemented by driver, in order to achieve the rapid follow of the system current. The position loop was completed by the digital signal processor (DSP) and the position feedback was achieved by high precision linear scales. Feed forward control and position feedback Proportion Integration Differentiation (PID) control were applied in order to compensate for dynamic lag and improve the response speed of the system. And the high precision and efficiency of the system were verified by simulation and experiments. The results demonstrated that the performance of Z-direction gantry was obviously improved, having high precision, quick responses, strong real-time and easily to expend for higher precision.

Talbot phase-contrast X-ray imaging for the small joints of the hand

PubMed Central

Stutman, Dan; Beck, Thomas J; Carrino, John A; Bingham, Clifton O

2011-01-01

A high resolution radiographic method for soft tissues in the small joints of the hand would aid in the study and treatment of Rheumatoid Arthritis (RA) and Osteoarthritis (OA), which often attacks these joints. Of particular interest would be imaging with <100 μm resolution the joint cartilage, whose integrity is a main indicator of disease. Differential phase-contrast or refraction based X-ray imaging (DPC) with Talbot grating interferometers could provide such a method, since it enhances soft tissue contrast and it can be implemented with conventional X-ray tubes. A numerical joint phantom was first developed to assess the angular sensitivity and spectrum needed for a hand DPC system. The model predicts that due to quite similar refraction indexes for joint soft tissues, the refraction effects are very small, requiring high angular resolution. To compare our model to experiment we built a high resolution bench-top interferometer using 10 μm period gratings, a W anode tube and a CCD based detector. Imaging experiments on animal cartilage and on a human finger support the model predictions. For instance, the estimated difference between the index of refraction of cartilage and water is of only several percent at ~25 keV mean energy, comparable to that between the linear attenuation coefficients. The potential advantage of DPC imaging comes thus mainly from the edge enhancement at the soft tissue interfaces. Experiments using a cadaveric human finger are also qualitatively consistent with the joint model, showing that refraction contrast is dominated by tendon embedded in muscle, with the cartilage layer difficult to observe in our conditions. Nevertheless, the model predicts that a DPC radiographic system for the small hand joints of the hand could be feasible using a low energy quasi-monochromatic source, such as a K-edge filtered Rh or Mo tube, in conjunction with a ~2 m long ‘symmetric’ interferometer operated in a high Talbot order. PMID:21841214

Talbot phase-contrast x-ray imaging for the small joints of the hand

NASA Astrophysics Data System (ADS)

Stutman, Dan; Beck, Thomas J.; Carrino, John A.; Bingham, Clifton O.

2011-09-01

A high-resolution radiographic method for soft tissues in the small joints of the hand would aid in the study and treatment of rheumatoid arthritis (RA) and osteoarthritis (OA), which often attacks these joints. Of particular interest would be imaging with <100 µm resolution the joint cartilage, whose integrity is a main indicator of disease. Differential phase-contrast (DPC) or refraction-based x-ray imaging with Talbot grating interferometers could provide such a method, since it enhances soft tissue contrast and can be implemented with conventional x-ray tubes. A numerical joint phantom was first developed to assess the angular sensitivity and spectrum needed for a hand DPC system. The model predicts that, due to quite similar refraction indexes for joint soft tissues, the refraction effects are very small, requiring high angular resolution. To compare our model to experiment we built a high-resolution bench-top interferometer using 10 µm period gratings, a W anode tube and a CCD-based detector. Imaging experiments on animal cartilage and on a human finger support the model predictions. For instance, the estimated difference between the index of refraction of cartilage and water is of only several percent at ~25 keV mean energy, comparable to that between the linear attenuation coefficients. The potential advantage of DPC imaging thus comes mainly from the edge enhancement at the soft tissue interfaces. Experiments using a cadaveric human finger are also qualitatively consistent with the joint model, showing that refraction contrast is dominated by tendon embedded in muscle, with the cartilage layer difficult to observe in our conditions. Nevertheless, the model predicts that a DPC radiographic system for the small hand joints of the hand could be feasible using a low energy quasi-monochromatic source, such as a K-edge filtered Rh or Mo tube, in conjunction with a ~2 m long 'symmetric' interferometer operated in a high Talbot order.

Single-shot Z(eff) dense plasma diagnostic through simultaneous refraction and attenuation measurements with a Talbot-Lau x-ray moiré deflectometer.

PubMed

Valdivia, M P; Stutman, D; Finkenthal, M

2015-04-01

The Talbot-Lau x-ray moiré deflectometer is a powerful plasma diagnostic capable of delivering simultaneous refraction and attenuation information through the accurate detection of x-ray phase shift and intensity. The diagnostic can provide the index of refraction n=1-δ+iβ of an object (dense plasma, for example) placed in the x-ray beam by independently measuring both δ and β, which are directly related to the electron density n(e) and the attenuation coefficient μ, respectively. Since δ and β depend on the effective atomic number Z(eff), a map can be obtained from the ratio between phase and absorption images acquired in a single shot. The Talbot-Lau x-ray moiré deflectometer and its corresponding data acquisition and processing are briefly described to illustrate how the above is achieved; Z(eff) values of test objects within the 4-12 range were obtained experimentally through simultaneous refraction and attenuation measurements. We show that Z(eff) mapping of objects does not require previous knowledge of sample length or shape. The determination of Z(eff) from refraction and attenuation measurements with moiré deflectometry could be of high interest to various domains of high energy density research, such as shocked materials and inertial confinement fusion experiments, as well as material science and nondestructive testing.

An x-ray backlit Talbot-Lau deflectometer for high-energy-density electron density diagnostics.

PubMed

Valdivia, M P; Stutman, D; Stoeckl, C; Theobald, W; Mileham, C; Begishev, I A; Bromage, J; Regan, S P

2016-02-01

X-ray phase-contrast techniques can measure electron density gradients in high-energy-density plasmas through refraction induced phase shifts. An 8 keV Talbot-Lau interferometer consisting of free standing ultrathin gratings was deployed at an ultra-short, high-intensity laser system using K-shell emission from a 1-30 J, 8 ps laser pulse focused on thin Cu foil targets. Grating survival was demonstrated for 30 J, 8 ps laser pulses. The first x-ray deflectometry images obtained under laser backlighting showed up to 25% image contrast and thus enabled detection of electron areal density gradients with a maximum value of 8.1 ± 0.5 × 10(23) cm(-3) in a low-Z millimeter sized sample. An electron density profile was obtained from refraction measurements with an error of <8%. The 50 ± 15 μm spatial resolution achieved across the full field of view was found to be limited by the x-ray source-size, similar to conventional radiography.

Noiseless intensity amplification of repetitive signals by coherent addition using the temporal Talbot effect

PubMed Central

Maram, Reza; Van Howe, James; Li, Ming; Azaña, José

2014-01-01

Amplification of signal intensity is essential for initiating physical processes, diagnostics, sensing, communications and measurement. During traditional amplification, the signal is amplified by multiplying the signal carriers through an active gain process, requiring the use of an external power source. In addition, the signal is degraded by noise and distortions that typically accompany active gain processes. We show noiseless intensity amplification of repetitive optical pulse waveforms with gain from 2 to ~20 without using active gain. The proposed method uses a dispersion-induced temporal self-imaging (Talbot) effect to redistribute and coherently accumulate energy of the original repetitive waveforms into fewer replica waveforms. In addition, we show how our passive amplifier performs a real-time average of the wave-train to reduce its original noise fluctuation, as well as enhances the extinction ratio of pulses to stand above the noise floor. Our technique is applicable to repetitive waveforms in any spectral region or wave system. PMID:25319207

An x-ray backlit Talbot-Lau deflectometer for high-energy-density electron density diagnostics

DOE PAGES

Valdivia, M. P.; Stutman, D.; Stoeckl, C.; ...

2016-02-10

X-ray phase-contrast techniques can measure electron density gradients in high-energy-density plasmas through refraction induced phase shifts. An 8 keV Talbot-Lau interferometer consisting of free standing ultrathin gratings was deployed at an ultra-short, high-intensity laser system using K-shell emission from a 1-30 J, 8 ps laser pulse focused on thin Cu foil targets. Grating survival was demonstrated for 30 J, 8 ps laser pulses. The first x-ray deflectometry images obtained under laser backlighting showed up to 25% image contrast and thus enabled detection of electron areal density gradients with a maximum value of 8.1 ± 0.5 × 10 23 cm ₋3more » in a low-Z millimeter sized sample. An electron density profile was obtained from refraction measurements with an error of <8%. We found the 50 ± 15 μm spatial resolution achieved across the full field of view was limited by the x-ray source-size, similar to conventional radiography.« less

Fabrication of high aspect grating using bonded substrate for X-ray refraction imaging by Talbot-Lau interferometer

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

Tada, Takuji; Murakoshi, Dai; Ishii, Hiroyasu

2012-07-31

In order to improve the image quality of X-ray refraction images using a Talbot-Lau interferometer, we have been attempting to fabricate gratings with high aspect ratio. In our attempt, deep grooves of grating structure were channeled on a Si substrate bonded by Au diffusion bonding method, and the grooves were filled with Au where the Au layer used for the bonding Si substrate was acting as a seed layer of Au electroplating. From the results of a visibility measurement and a cross sectional SEM image, it was confirmed that the grooves with a pitch of 5.8 {mu}m and a depthmore » of 100 {mu}m could be successfully filled with Au over a large area of 72 Multiplication-Sign 80 mm{sup 2}. Using this grating, the X-ray refraction images for the cartilage of a knee joint of a livestock pig could be obtained where SPS method was employed for the single-shot image acquisition.« less

Large-angle x-ray scatter in Talbot-Lau interferometry for breast imaging

PubMed Central

Vedantham, Srinivasan; Shi, Linxi; Karellas, Andrew

2014-01-01

Monte Carlo simulations were used to investigate large-angle x-ray scatter at design energy of 25 keV during small field of view (9.6 cm × 5 cm) differential phase contrast imaging of the breast using Talbot-Lau interferometry. Homogenous, adipose and fibroglandular breasts of uniform thickness ranging from 2 to 8 cm encompassing the field of view were modeled. Theoretically determined transmission efficiencies of the gratings were used to validate the Monte Carlo simulations, followed by simulations to determine the x-ray scatter reaching the detector. The recorded x-ray scatter was classified into x-ray photons that underwent at least one Compton interaction (incoherent scatter) and Rayleigh interaction alone (coherent scatter) for further analysis. Monte Carlo based estimates of transmission efficiencies showed good correspondence (r2 > 0.99) with theoretical estimates. Scatter-to-primary ratio increased with increasing breast thickness, ranging from 0.11 to 0.22 for 2 to 8 cm thick adipose breasts and from 0.12 to 0.28 for 2 to 8 cm thick fibroglandular breasts. The analyzer grating reduced incoherent scatter by ~18% for 2 cm thick adipose breast and by ~35% for 8 cm thick fibroglandular breast. Coherent scatter was the dominant contributor to the total scatter. Coherent-to-incoherent scatter ratio ranged from 2.2 to 3.1 for 2 to 8 cm thick adipose breasts and from 2.7 to 3.4 for 2 to 8 cm thick fibroglandular breasts. PMID:25295630

Adjustable repetition-rate multiplication of optical pulses using fractional temporal Talbot effect with preceded binary intensity modulation

NASA Astrophysics Data System (ADS)

Xie, Qijie; Zheng, Bofang; Shu, Chester

2017-05-01

We demonstrate a simple approach for adjustable multiplication of optical pulses in a fiber using the temporal Talbot effect. Binary electrical patterns are used to control the multiplication factor in our approach. The input 10 GHz picosecond pulses are pedestal-free and are shaped directly from a CW laser. The pulses are then intensity modulated by different sets of binary patterns prior to entering a fiber of fixed dispersion. Tunable repetition-rate multiplication by different factors of 2, 4, and 8 have been achieved and up to 80 GHz pulse train has been experimentally generated. We also evaluate numerically the influence of the extinction ratio of the intensity modulator on the performance of the multiplied pulse train. In addition, the impact of the modulator bias on the uniformity of the output pulses has also been analyzed through simulation and experiment and a good agreement is reached. Last, we perform numerical simulation on the RF spectral characteristics of the output pulses. The insensitivity of the signal-to-subharmonic noise ratio (SSNR) to the laser linewidth shows that our multiplication scheme is highly tolerant to the incoherence of the input optical pulses.

A new method for fusion, denoising and enhancement of x-ray images retrieved from Talbot-Lau grating interferometry.

PubMed

Scholkmann, Felix; Revol, Vincent; Kaufmann, Rolf; Baronowski, Heidrun; Kottler, Christian

2014-03-21

This paper introduces a new image denoising, fusion and enhancement framework for combining and optimal visualization of x-ray attenuation contrast (AC), differential phase contrast (DPC) and dark-field contrast (DFC) images retrieved from x-ray Talbot-Lau grating interferometry. The new image fusion framework comprises three steps: (i) denoising each input image (AC, DPC and DFC) through adaptive Wiener filtering, (ii) performing a two-step image fusion process based on the shift-invariant wavelet transform, i.e. first fusing the AC with the DPC image and then fusing the resulting image with the DFC image, and finally (iii) enhancing the fused image to obtain a final image using adaptive histogram equalization, adaptive sharpening and contrast optimization. Application examples are presented for two biological objects (a human tooth and a cherry) and the proposed method is compared to two recently published AC/DPC/DFC image processing techniques. In conclusion, the new framework for the processing of AC, DPC and DFC allows the most relevant features of all three images to be combined in one image while reducing the noise and enhancing adaptively the relevant image features. The newly developed framework may be used in technical and medical applications.

3850:..At the Cosmonaut Hotel crew quarters in Baikonur, Kazakhstan, Expedition 44 prime crewmember Kjell Lindgren of NASA (right) plants a tree in his name in a traditional pre-launch ceremony July 15. Assisting are crewmates Kimiya Yui of the Japan Aerospace Exploration Agency (left) and Oleg Kononenko of the Russian Federal Space Agency (Roscosmos, center), Yui, Kononenko and Lindgren will launch July 23, Kazakh time on the Soyuz TMA-17M spacecraft from the Baikonur Cosmodrome for a five-month mission on the International Space Station...Credit: Gagarin Cosmonaut Training Center.

NASA Image and Video Library

2015-07-15

3850: At the Cosmonaut Hotel crew quarters in Baikonur, Kazakhstan, Expedition 44 prime crewmember Kjell Lindgren of NASA (right) plants a tree in his name in a traditional pre-launch ceremony July 15. Assisting are crewmates Kimiya Yui of the Japan Aerospace Exploration Agency (left) and Oleg Kononenko of the Russian Federal Space Agency (Roscosmos, center), Yui, Kononenko and Lindgren will launch July 23, Kazakh time on the Soyuz TMA-17M spacecraft from the Baikonur Cosmodrome for a five-month mission on the International Space Station. Credit: Gagarin Cosmonaut Training Center

Talbot-Lau x-ray deflectometry phase-retrieval methods for electron density diagnostics in high-energy density experiments.

PubMed

Valdivia, Maria Pia; Stutman, Dan; Stoeckl, Christian; Mileham, Chad; Begishev, Ildar A; Bromage, Jake; Regan, Sean P

2018-01-10

Talbot-Lau x-ray interferometry uses incoherent x-ray sources to measure refraction index changes in matter. These measurements can provide accurate electron density mapping through phase retrieval. An adaptation of the interferometer has been developed in order to meet the specific requirements of high-energy density experiments. This adaptation is known as a moiré deflectometer, which allows for single-shot capabilities in the form of interferometric fringe patterns. The moiré x-ray deflectometry technique requires a set of object and reference images in order to provide electron density maps, which can be costly in the high-energy density environment. In particular, synthetic reference phase images obtained ex situ through a phase-scan procedure, can provide a feasible solution. To test this procedure, an object phase map was retrieved from a single-shot moiré image obtained from a plasma-produced x-ray source. A reference phase map was then obtained from phase-stepping measurements using a continuous x-ray tube source in a small laboratory setting. The two phase maps were used to retrieve an electron density map. A comparison of the moiré and phase-stepping phase-retrieval methods was performed to evaluate single-exposure plasma electron density mapping for high-energy density and other transient plasma experiments. It was found that a combination of phase-retrieval methods can deliver accurate refraction angle mapping. Once x-ray backlighter quality is optimized, the ex situ method is expected to deliver electron density mapping with improved resolution. The steps necessary for improved diagnostic performance are discussed.

View from the East: Arab Perceptions of United States Presence and Policy

DTIC Science & Technology

2003-02-01

View from the East: Arab Perceptions of United States Presence and Policy Brent J . Talbot and Michael B. Meyer INSS...IMPLICATIONS FOR US POLICY IN THE MIDDLE EAST, Brent J . Talbot Introduction 1 The Perception Problem 3 The Consensus Issue 11...THE ARAB PERCEPTION AND CONSENSUS PROBLEMS: IMPLICATIONS FOR US POLICY IN THE MIDDLE EAST, Brent J . Talbot EXECUTIVE SUMMARY This paper is a

Progress in coherent lithography using table-top extreme ultraviolet lasers

NASA Astrophysics Data System (ADS)

Li, Wei

Nanotechnology has drawn a wide variety of attention as interesting phenomena occurs when the dimension of the structures is in the nanometer scale. The particular characteristics of nanoscale structures had enabled new applications in different fields in science and technology. Our capability to fabricate these nanostructures routinely for sure will impact the advancement of nanoscience. Apart from the high volume manufacturing in semiconductor industry, a small-scale but reliable nanofabrication tool can dramatically help the research in the field of nanotechnology. This dissertation describes alternative extreme ultraviolet (EUV) lithography techniques which combine table-top EUV laser and various cost-effective imaging strategies. For each technique, numerical simulations, system design, experiment result and its analysis will be presented. In chapter II, a brief review of the main characteristics of table-top EUV lasers will be addressed concentrating on its high power and large coherence radius that enable the lithography application described herein. The development of a Talbot EUV lithography system which is capable of printing 50nm half pitch nanopatterns will be illustrated in chapter III. A detailed discussion of its resolution limit will be presented followed by the development of X-Y-Z positioning stage, the fabrication protocol for diffractive EUV mask, and the pattern transfer using self- developed ion beam etching, and the dose control unit. In addition, this dissertation demonstrated the capability to fabricate functional periodic nanostructures using Talbot EUV lithography. After that, resolution enhancement techniques like multiple exposure, displacement Talbot EUV lithography, fractional Talbot EUV lithography, and Talbot lithography using 18.9nm amplified spontaneous emission laser will be demonstrated. Chapter IV will describe a hybrid EUV lithography which combines the Talbot imaging and interference lithography rendering a high resolution

Preliminary physical stratigraphy, biostratigraphy, and geophysical data of the USGS South Dover Bridge Core, Talbot County, Maryland

USGS Publications Warehouse

Alemán González, Wilma B.; Powars, David S.; Seefelt, Ellen L.; Edwards, Lucy E.; Self-Trail, Jean M.; Durand, Colleen T.; Schultz, Arthur P.; McLaughlin, Peter P.

2012-01-01

The South Dover Bridge (SDB) corehole was drilled in October 2007 in Talbot County, Maryland. The main purpose for drilling this corehole was to characterize the Upper Cretaceous and Paleogene lithostratigraphy and biostratigraphy of the aquifers and confining units of this region. The data obtained from this core also will be used as a guide to geologic mapping and to help interpret well data from the eastern part of the Washington East 1:100,000-scale map near the town of Easton, Md. Core drilling was conducted to a depth of 700 feet (ft). The Cretaceous section was not penetrated due to technical problems during drilling. This project was funded by the U.S. Geological Survey’s (USGS) Eastern Geology and Paleoclimate Science Center (EGPSC) as part of the Geology of the Atlantic Watersheds Project; this project was carried out in cooperation with the Maryland Geological Survey (MGS) through partnerships with the Aquifer Characterization Program of the USGS’s Maryland-Delaware-District of Columbia Water Science Center and the National Cooperative Geologic Mapping Program. The SDB corehole was drilled by the USGS drilling crew in the northeastern corner of the Trappe 7.5-minute quadrangle, near the type locality of the Boston Cliffs member of the Choptank Formation. Geophysical logs (gamma ray, single point resistance, and 16-inch and 64-inch normal resistivity) were run to a depth of 527.5 ft; the total depth of 700.0 ft could not be reached because of the collapse of the lower part of the hole. Of the 700.0 ft drilled, 531.8 ft of core were recovered, representing a 76 percent core recovery. The elevation of the top of the corehole is approximately 12 ft above mean sea level; its coordinates are lat 38°44′49.34″N. and long 76°00′25.09″W. (38.74704N., 76.00697W. in decimal degrees). A groundwater monitoring well was not installed at this site. The South Dover Bridge corehole was the first corehole that will be used to better understand the geology and

Transformation of light double cones in the human retina: the origin of trichromatism, of 4D-spatiotemporal vision, and of patchwise 4D Fourier transformation in Talbot imaging

NASA Astrophysics Data System (ADS)

Lauinger, Norbert

1997-09-01

The interpretation of the 'inverted' retina of primates as an 'optoretina' (a light cones transforming diffractive cellular 3D-phase grating) integrates the functional, structural, and oscillatory aspects of a cortical layer. It is therefore relevant to consider prenatal developments as a basis of the macro- and micro-geometry of the inner eye. This geometry becomes relevant for the postnatal trichromatic synchrony organization (TSO) as well as the adaptive levels of human vision. It is shown that the functional performances, the trichromatism in photopic vision, the monocular spatiotemporal 3D- and 4D-motion detection, as well as the Fourier optical image transformation with extraction of invariances all become possible. To transform light cones into reciprocal gratings especially the spectral phase conditions in the eikonal of the geometrical optical imaging before the retinal 3D-grating become relevant first, then in the von Laue resp. reciprocal von Laue equation for 3D-grating optics inside the grating and finally in the periodicity of Talbot-2/Fresnel-planes in the near-field behind the grating. It is becoming possible to technically realize -- at least in some specific aspects -- such a cortical optoretina sensor element with its typical hexagonal-concentric structure which leads to these visual functions.

Survival resonances in an atom-optics system driven by temporally and spatially periodic dissipation

NASA Astrophysics Data System (ADS)

Chai, Shijie; Fekete, Julia; McDowall, Peter; Coop, Simon; Lindballe, Thue; Andersen, Mikkel F.

2018-03-01

We investigate laser-cooled atoms periodically driven by pulsed standing waves of light tuned close to an open atomic transition. This nonunitary system displays survival resonances for certain driving frequencies. The survival resonances emerge as a result of the matter-wave Talbot-Lau effect, similar to the Talbot effect causing quantum resonances in the atom optics δ -kicked rotor. Since the Talbot-Lau effect occurs for incoherent waves, the survival resonances can be observed using thermal atoms. A microlensing effect can enhance the height and incisiveness of the resonances. This may find applications in precision measurements.

Lindgren exercises in Node 3 module

NASA Image and Video Library

2015-07-28

ISS044E024392 (07/28/2015) --- Newly arrived NASA astronaut Kjell Lindgren exercises on the International Space Station using the Advanced Resistive Exercise Device to help mitigate the potentially adverse effects of long duration stays in microgravity.

Lindgren conducts Veg-01 Plant Pillow Refill

NASA Image and Video Library

2015-12-02

Flight engineer Kjell Lindgren poses with zinnia plants in the Veggie facility during Plant Pillow water refill operations. Image was taken in the Columbus European Laboratory and released by Lindgren on social media. "Our zinnias are looking good! #SpaceGardener"

Geophysicists

NASA Astrophysics Data System (ADS)

2004-02-01

In Memoriam: Francis R. ``Joe'' Boyd, John B. Ivey, William Warren Kellogg, Norma N. McMillin, Henry T. R. Radoski, William (Bill) Sackett, John W. Sherman, III, Kjell Petter Skjerlie, Peter Bernard Smoor; Recent Ph.D.s: Joan Bech, Mark Pickett

30-lens interferometer for high energy x-rays

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

Lyubomirskiy, M., E-mail: lyubomir@esrf.fr; Snigireva, I., E-mail: irina@esrf.fr; Vaughan, G.

2016-07-27

We report a hard X-ray multilens interferometer consisting of 30 parallel compound refractive lenses. Under coherent illumination each CRL creates a diffraction limited focal spot - secondary source. An overlapping of coherent beams from these sources resulting in the interference pattern which has a rich longitudinal structure in accordance with the Talbot imaging formalism. The proposed interferometer was experimentally tested at ID11 ESRF beamline for the photon energies 32 keV and 65 keV. The fundamental and fractional Talbot images were recorded with the high resolution CCD camera. An effective source size in the order of 15 µm was determined frommore » the first Talbot image proving that the multilens interferometer can be used as a high resolution beam diagnostic tool.« less

Free-space entangled quantum carpets

NASA Astrophysics Data System (ADS)

Barros, Mariana R.; Ketterer, Andreas; Farías, Osvaldo Jiménez; Walborn, Stephen P.

2017-04-01

The Talbot effect in quantum physics is known to produce intricate patterns in the probability distribution of a particle, known as "quantum carpets," corresponding to the revival and replication of the initial wave function. Recently, it was shown that one can encode a D -level qudit in such a way that the Talbot effect can be used to process the D -dimensional quantum information [Farías et al., Phys. Rev. A 91, 062328 (2015), 10.1103/PhysRevA.91.062328]. Here we introduce a scheme to produce free-propagating "entangled quantum carpets" with pairs of photons produced by spontaneous parametric down-conversion. First we introduce an optical device that can be used to synthesize arbitrary superposition states of Talbot qudits. Sending spatially entangled photon pairs through a pair of these devices produces an entangled pair of qudits. As an application, we show how the Talbot effect can be used to test a D -dimensional Bell inequality. Numerical simulations show that violation of the Bell inequality depends strongly on the amount of spatial correlation in the initial two-photon state. We briefly discuss how our optical scheme might be adapted to matter wave experiments.

Combustion Integration Rack (CIR)/FLame Extinguishment Experiment (FLEX)-2J Fiber Replace

NASA Image and Video Library

2015-08-20

ISS044E064666 (08/20/2015) --- NASA astronaut Kjell Lindgren replaces items inside the Multi-user Droplet Combustion Apparatus found inside the station’s Combustion Integrated Rack (CIR.) The CIR houses hardware capable of performing combustion experiments to further research of combustion in microgravity.

Ideal-observer detectability in photon-counting differential phase-contrast imaging using a linear-systems approach

PubMed Central

Fredenberg, Erik; Danielsson, Mats; Stayman, J. Webster; Siewerdsen, Jeffrey H.; Åslund, Magnus

2012-01-01

Purpose: To provide a cascaded-systems framework based on the noise-power spectrum (NPS), modulation transfer function (MTF), and noise-equivalent number of quanta (NEQ) for quantitative evaluation of differential phase-contrast imaging (Talbot interferometry) in relation to conventional absorption contrast under equal-dose, equal-geometry, and, to some extent, equal-photon-economy constraints. The focus is a geometry for photon-counting mammography. Methods: Phase-contrast imaging is a promising technology that may emerge as an alternative or adjunct to conventional absorption contrast. In particular, phase contrast may increase the signal-difference-to-noise ratio compared to absorption contrast because the difference in phase shift between soft-tissue structures is often substantially larger than the absorption difference. We have developed a comprehensive cascaded-systems framework to investigate Talbot interferometry, which is a technique for differential phase-contrast imaging. Analytical expressions for the MTF and NPS were derived to calculate the NEQ and a task-specific ideal-observer detectability index under assumptions of linearity and shift invariance. Talbot interferometry was compared to absorption contrast at equal dose, and using either a plane wave or a spherical wave in a conceivable mammography geometry. The impact of source size and spectrum bandwidth was included in the framework, and the trade-off with photon economy was investigated in some detail. Wave-propagation simulations were used to verify the analytical expressions and to generate example images. Results: Talbot interferometry inherently detects the differential of the phase, which led to a maximum in NEQ at high spatial frequencies, whereas the absorption-contrast NEQ decreased monotonically with frequency. Further, phase contrast detects differences in density rather than atomic number, and the optimal imaging energy was found to be a factor of 1.7 higher than for absorption

The Journal of Suggestive-Accelerative Learning and Teaching. Volume 4, Number 1, Spring 1979.

ERIC Educational Resources Information Center

Schuster, Donald, Ed.

1979-01-01

This volume presents articles on aspects of suggestive learning with emphasis on foreign language instruction. The following articles and reviews are included: (1) "Biofeedback in Holistic Education," by Larry O. Rouse; (2) "Report on the Helsinki Suggestopedia Seminar, June, 1978," by Kjell Weinius; (3) "Suggestology and…

Nicole: Suicide and Terminal Illness.

ERIC Educational Resources Information Center

Saunders, Judith M.; And Others

1993-01-01

Presents case summary of 58-year-old woman, terminally ill with cancer, who is contemplating suicide. Includes comments from Kjell Rudestam from the Fielding Institute and from Margaret Battin from the University of Utah who debate appropriate responses to people who contemplate suicide because of terminal illness. (NB)

Design and Fabrication of Aspheric Microlens Array for Optical Read-Only-Memory Card System

NASA Astrophysics Data System (ADS)

Kim, Hongmin; Jeong, Gibong; Kim, Young‑Joo; Kang, Shinill

2006-08-01

An optical head based on the Talbot effect with an aspheric microlens array for an optical read-only-memory (ROM) card system was designed and fabricated. The mathematical expression for the wavefield diffracted by a periodic microlens array showed that the amplitude distribution at the Talbot plane from the focal plane of the microlens array was identically equal to that at the focal plane. To use a reflow microlens array as a master pattern of an ultraviolet-imprinted (UV-imprinted) microlens array, the reflow microlens was defined as having an aspheric shape. To obtain optical probes with good optical qualities, a microlens array with the minimum spherical aberration was designed by ray tracing. The reflow condition was optimized to realize the master pattern of a microlens with a designed aspheric shape. The intensity distribution of the optical probes at the Talbot plane from the focal plane showed a diffraction-limited shape.

Variations in the source, metal content and bioreactivity of technogenic aerosols: a case study from Port Talbot, Wales, UK.

PubMed

Moreno, Teresa; Merolla, Luciano; Gibbons, Wes; Greenwell, Leona; Jones, Tim; Richards, Roy

2004-10-15

Atmospheric aerosol samples were collected during different prevailing wind directions from a site located close to a busy motorway, a major steelworks, and the town of Port Talbot (Wales, UK). A high-volume collector was used (1100 l/min), enabling relatively large amounts of particulate matter (PM(10-2.5) and PM(2.5)) samples to be obtained on a polyurethane foam [PUF, H(2)N-C(O)O-CH(2)CH(3)] substrate over periods of 2-7 days. Four samples were chosen to exemplify different particle mixtures: SE- and NE-derived samples for particles moving along and across the motorway, a NW-derived sample from the town, and a mixed SW/SE-derived sample containing a mixture of particles from both steelworks and motorway. The latter sample showed the highest average collection rate (0.9 mg/h, 13 microg/m(3)) and included a prominent pollution episode when rainy winds were blowing from the direction of the steelworks. Both NW and SE samples were collected under dry conditions and show the same collection rate (0.7 mg/h, 10 microg/m(3)), whereas the NE sample was collected during wetter weather and shows the lowest rate (0.3 mg/h, 5 microg/m(3)). Scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis system (EDX) analyses show all samples are dominated by elemental and organic carbon compounds (EOCC) and nitrates, with lesser amounts of sulphates, felsic silicates, chlorides and metals. ICP-MS analyses show the SW/SE sample to be richest in metals, especially Fe, Zn, Ni, and Mn, these being attributed to an origin from the steelworks. The SE sample, blown along the motorway corridor, shows enhanced levels of Pb, V, Ti, As, and Ce, these metals being interpreted as defining a traffic-related chemical fingerprint. The NW sample shows a very low metal content. DNA plasmid assay data on the samples show TM(50) values varying from 66 to 175 microg/ml for the adjusted whole sample and 89 to 203 microg/ml for the soluble fraction. The SW/SE-mixed metalliferous sample

ISS Expedition 45 / 46 Underwater Crew Training

NASA Image and Video Library

2015-02-03

Underwater camera views of ISS Expedition 45 (Soyuz 42) crewmember Scott Kelly and ISS Expedition 46 (Soyuz 43) crewmember Kjell Lindgren during ISS Extravehicular Activity (EVA) Maintenance 9 Training (PMA/PMM Relocate) at JSC's Neutral Buoyancy Lab (NBL) Pool Deck at Sonny Carter Training Facility (SCTF). TIME magazine film crew filming activities.

Adult Education in Transition: Three Cases and Periods Compared

ERIC Educational Resources Information Center

Engesbak, Heidi; Tonseth, Christin; Fragoso, Antonio; Lucio-Villegas, Emilio

2010-01-01

The focus of this article is the development of adult education. As Kjell Rubenson maintains, adult education has gone through three eras of development: the humanistic, the strong economic period and a softer version of the economic period. Based on this model, we examine whether the development of adult education has similarities across…

Taxonomic changes of some neotropical species of Arctiini Leach (Lepidoptera: Erebidae: Arctiinae).

PubMed

Beccacece, Hernán Mario; Zapata, Adriana Inés

2017-05-30

Arctiini (Lepidoptera, Erebidae, Arctiinae) is the most speciose tribe of tiger moths. In this study, the taxonomy of some Neotropical species of this tribe is reviewed based on habitus and, in some cases, genitalia of type specimens. Lectotypes are designated for two names. Four new combinations are proposed: Agaraea sericeum (Zerny, 1931) comb. n., Biturix nigrostriata (Rothschild, 1909) comb. n., Carales fasciatus (Rothschild, 1909) comb. n. and Opharus pallida (Dognin, 1910) comb. n. Six new synonymies are proposed: Agaraea nigrotuberculata Bryk, 1953 (=Agaraea klagesi (Rothschild, 1909)), Opharus ochracea Joicey & Talbot, 1918 and Pelochyta fergusoni Watson & Goodger, 1986 (=Opharus pallida (Dognin, 1910)), Melese flavescens Joicey & Talbot, 1918 (=Melese paranensis Dognin, 1911), Leucanopsis infucata (Berg, 1882) (=Pareuchaetes aurata aurata (Butler, 1875)) and Tessellota pura Breyer, 1957 (=Tessellota cancellata (Burmeister, 1878)). Moreover, Opharus ochracea Joicey & Talbot, 1918 comb. rev. is returned to the original genus. For each rearrangement, both remarks and information about type specimens are provided.

Emergency Mask OBT

NASA Image and Video Library

2015-07-28

ISS044E025035 (07/29/2015) --- NASA astronaut Kjell Lindgren wears protective breathing apparatus that would be used in the unlikely event of a fire or hazardous chemical leak inside the pressurized air volume of the International Space Station. Familiarization of safety and emergency equipment is standard practice for all newly arrived crew members.

Emergency Mask OBT

NASA Image and Video Library

2015-07-28

ISS044E025035 (07/29/2015) --- NASA astronaut Kjell Lindgren prepares to don protective breathing apparatus that would be used in the unlikely event of a fire or hazardous chemical leak inside the pressurized air volume of the International Space Station. Familiarization of safety and emergency equipment is standard practice for all newly arrived crew members.

Veg-01 Plant Harvest

NASA Image and Video Library

2015-08-10

ISS044E045825 (08/11/2015) --- NASA astronauts Scott Kelly and Kjell Lindgren on the International Space Station are getting their taste buds ready for the first taste of food that's grown, harvested and eaten in space, a critical step on the path to Mars. The crew took their first bites on Aug. 10, 2015.

2013 Inaugural Parade

NASA Image and Video Library

2013-01-21

The Orion space capsule along with NASA Astronauts Lee Morin, Alvin Drew, Kjell Lindgren, Serena Aunon, Kate Rubins, and Mike Massimino pass the Presidential viewing stand and President Barack Obama during the inaugural parade honoring Obama, Monday Jan. 21, 2013, in Washington. Obama was sworn-in as the nation's 44th President earlier in the day. Photo Credit: (NASA/Bill Ingalls)

Feasibility evaluation of a neutron grating interferometer with an analyzer grating based on a structured scintillator.

PubMed

Kim, Youngju; Kim, Jongyul; Kim, Daeseung; Hussey, Daniel S; Lee, Seung Wook

2018-03-01

We introduce an analyzer grating based on a structured scintillator fabricated by a gadolinium oxysulfide powder filling method for a symmetric Talbot-Lau neutron grating interferometer. This is an alternative way to analyze the Talbot self-image of a grating interferometer without using an absorption grating to block neutrons. Since the structured scintillator analyzer grating itself generates the signal for neutron detection, we do not need an additional scintillator screen as an absorption analyzer grating. We have developed and tested an analyzer grating based on a structured scintillator in our symmetric Talbot-Lau neutron grating interferometer to produce high fidelity absorption, differential phase, and dark-field contrast images. The acquired images have been compared to results of a grating interferometer utilizing a typical absorption analyzer grating with two commercial scintillation screens. The analyzer grating based on the structured scintillator enhances interference fringe visibility and shows a great potential for economical fabrication, compact system design, and so on. We report the performance of the analyzer grating based on a structured scintillator and evaluate its feasibility for the neutron grating interferometer.

Feasibility evaluation of a neutron grating interferometer with an analyzer grating based on a structured scintillator

NASA Astrophysics Data System (ADS)

Kim, Youngju; Kim, Jongyul; Kim, Daeseung; Hussey, Daniel. S.; Lee, Seung Wook

2018-03-01

We introduce an analyzer grating based on a structured scintillator fabricated by a gadolinium oxysulfide powder filling method for a symmetric Talbot-Lau neutron grating interferometer. This is an alternative way to analyze the Talbot self-image of a grating interferometer without using an absorption grating to block neutrons. Since the structured scintillator analyzer grating itself generates the signal for neutron detection, we do not need an additional scintillator screen as an absorption analyzer grating. We have developed and tested an analyzer grating based on a structured scintillator in our symmetric Talbot-Lau neutron grating interferometer to produce high fidelity absorption, differential phase, and dark-field contrast images. The acquired images have been compared to results of a grating interferometer utilizing a typical absorption analyzer grating with two commercial scintillation screens. The analyzer grating based on the structured scintillator enhances interference fringe visibility and shows a great potential for economical fabrication, compact system design, and so on. We report the performance of the analyzer grating based on a structured scintillator and evaluate its feasibility for the neutron grating interferometer.

Spatial resolution characterization of differential phase contrast CT systems via modulation transfer function (MTF) measurements

NASA Astrophysics Data System (ADS)

Li, Ke; Zambelli, Joseph; Bevins, Nicholas; Ge, Yongshuai; Chen, Guang-Hong

2013-06-01

By adding a Talbot-Lau interferometer to a conventional x-ray absorption computed tomography (CT) imaging system, both differential phase contrast (DPC) signal and absorption contrast signal can be simultaneously measured from the same set of CT measurements. The imaging performance of such multi-contrast x-ray CT imaging systems can be characterized with standard metrics such as noise variance, noise power spectrum, contrast-to-noise ratio, modulation transfer function (MTF), and task-based detectability index. Among these metrics, the measurement of the MTF can be challenging in DPC-CT systems due to several confounding factors such as phase wrapping and the difficulty of using fine wires as probes. To address these technical challenges, this paper discusses a viable and reliable method to experimentally measure the MTF of DPC-CT. It has been found that the spatial resolution of DPC-CT is degraded, when compared to that of the corresponding absorption CT, due to the presence of a source grating G0 in the Talbot-Lau interferometer. An effective MTF was introduced and experimentally estimated to describe the impact of the Talbot-Lau interferometer on the system MTF.

Current Approaches to Automated Information Evaluation and their Applicability to Priority Intelligence Requirement Answering

DTIC Science & Technology

2010-07-01

corresponding to various “ Elvises ” are highlighted, including Elvis Presley , skater Elvis Stojko, and Norwegian Elvis impersonator Kjell Elvis ...was Elvis born?” is Tupelo, MS. ‘ Elvis ’ is automatically interpreted as ‘ Elvis Presley ’ according to the highest-ranked results; no other Elvis is...Because Powerset is processing logical statements derived from a single source of data (Wikipedia), the answers do not converge on a single Elvis

75 FR 28630 - Maryland; Major Disaster and Related Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-21

..., Howard, Kent, Montgomery, Prince George's, Queen Anne's, Saint Mary's, Talbot, Washington, and Wicomico..., Calvert, Caroline, Carroll, Charles, Dorchester, Frederick, Garrett, Harford, Montgomery, Prince George's...

A general theory of interference fringes in x-ray phase grating imaging.

PubMed

Yan, Aimin; Wu, Xizeng; Liu, Hong

2015-06-01

The authors note that the concept of the Talbot self-image distance in x-ray phase grating interferometry is indeed not well defined for polychromatic x-rays, because both the grating phase shift and the fractional Talbot distances are all x-ray wavelength-dependent. For x-ray interferometry optimization, there is a need for a quantitative theory that is able to predict if a good intensity modulation is attainable at a given grating-to-detector distance. In this work, the authors set out to meet this need. In order to apply Fourier analysis directly to the intensity fringe patterns of two-dimensional and one-dimensional phase grating interferometers, the authors start their derivation from a general phase space theory of x-ray phase-contrast imaging. Unlike previous Fourier analyses, the authors evolved the Wigner distribution to obtain closed-form expressions of the Fourier coefficients of the intensity fringes for any grating-to-detector distance, even if it is not a fractional Talbot distance. The developed theory determines the visibility of any diffraction order as a function of the grating-to-detector distance, the phase shift of the grating, and the x-ray spectrum. The authors demonstrate that the visibilities of diffraction orders can serve as the indicators of the underlying interference intensity modulation. Applying the theory to the conventional and inverse geometry configurations of single-grating interferometers, the authors demonstrated that the proposed theory provides a quantitative tool for the grating interferometer optimization with or without the Talbot-distance constraints. In this work, the authors developed a novel theory of the interference intensity fringes in phase grating x-ray interferometry. This theory provides a quantitative tool in design optimization of phase grating x-ray interferometers.

Evaporative Cooling in a Holographic Atom Trap

NASA Technical Reports Server (NTRS)

Newell, Raymond

2003-01-01

We present progress on evaporative cooling of Rb-87 atoms in our Holographic Atom Trap (HAT). The HAT is formed by the interference of five intersecting YAG laser beams: atoms are loaded from a vapor-cell MOT into the bright fringes of the interference pattern through the dipole force. The interference pattern is composed of Talbot fringes along the direction of propagation of the YAG beams, prior to evaporative cooling each Talbot fringe contains 300,000 atoms at 50 micro-K and peak densities of 2 x 10(exp 14)/cu cm. Evaporative cooling is achieved through adiabatically decreasing the intensity of the YAG laser. We present data and calculations covering a range of HAT geometries and cooling procedures.

Mitigating the Tyranny, a Moral Responsibility

DTIC Science & Technology

2009-12-01

to their society they must be physically and emotionally equipped to handle life outside the warzone; it is, therefore, the military’s obligation...Moral Responsibilities of Victors in War, Warfare studies AY10 Coursebook , edited by Sharon McBride, (Maxwell AFB, Al: Air University Press, October... Coursebook , edited by Sharon McBride, page156-167. Maxwell AFB, AL [or Ala.]: Air University Press, October 2009. Myhr, Kjell-Ivar. ―Norsk F-16 pilot

iss045e152270

NASA Image and Video Library

2015-12-01

ISS045e152270 (12/01/2015) --- NASA astronaut Kjell Lindgren takes images of the Earth on board the International Space Station on Dec. 1, 2015 from the Cupola, the 360 degree viewing and robotic Canadarm 2 control area. Later this area will be used by Lindgren and NASA astronaut Scott Kelly to use the station’s Canadarm 2 robotic arm to reach out and grapple the Orbital ATK CRS-4 "Cygnus" spaceship full of equipment and supplies.

Two-dimensional periodic structures in solid state laser resonator

NASA Astrophysics Data System (ADS)

Okulov, Alexey Y.

1991-07-01

Transverse effects in nonlinear optical devices are being widely investigated. Recently, synchronization of a laser set by means of the Talbot effect has been demonstrated experimentally. This paper considers a Talbot cavity formed by a solid-state amplifying laser separated from the output mirror by a free space interval. This approach involves the approximation of the nonlinear medium as a thin layer, within which the diffraction is negligible. The other part of a resonator is empty, and the wave field is transformed by the Fresnel-Kirchoff integral. As a result, the dynamics of the transverse (and temporal) structure is computed by a successively iterated nonlinear local map (one- or two-dimensional) and a linear nonlocal map (generally speaking, infinitely dimensional).

19. DECK VIEW LOOKING FORWARD WITH MAST, RIGGING AND BOWSPRIT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. DECK VIEW LOOKING FORWARD WITH MAST, RIGGING AND BOWSPRIT DETAILS - HATCH COVER REMOVED TO SHOW CENTERBOARD TRUNK - KATHRYN-Two-sail Bateau "Skipjack", Dogwood Harbor, Chesapeake Bay, Tilghman, Talbot County, MD

Born’s rule as signature of a superclassical current algebra

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

Fussy, S.; Mesa Pascasio, J.; Institute for Atomic and Subatomic Physics, Vienna University of Technology, Operng. 9, 1040 Vienna

2014-04-15

We present a new tool for calculating the interference patterns and particle trajectories of a double-, three- and N-slit system on the basis of an emergent sub-quantum theory developed by our group throughout the last years. The quantum itself is considered as an emergent system representing an off-equilibrium steady state oscillation maintained by a constant throughput of energy provided by a classical zero-point energy field. We introduce the concept of a “relational causality” which allows for evaluating structural interdependences of different systems levels, i.e. in our case of the relations between partial and total probability density currents, respectively. Combined with themore » application of 21st century classical physics like, e.g., modern nonequilibrium thermodynamics, we thus arrive at a “superclassical” theory. Within this framework, the proposed current algebra directly leads to a new formulation of the guiding equation which is equivalent to the original one of the de Broglie–Bohm theory. By proving the absence of third order interferences in three-path systems it is shown that Born’s rule is a natural consequence of our theory. Considering the series of one-, double-, or, generally, of N-slit systems, with the first appearance of an interference term in the double slit case, we can explain the violation of Sorkin’s first order sum rule, just as the validity of all higher order sum rules. Moreover, the Talbot patterns and Talbot distance for an arbitrary N-slit device can be reproduced exactly by our model without any quantum physics tool. -- Highlights: •Calculating the interference patterns and particle trajectories of a double-, three- and N-slit system. •Deriving a new formulation of the guiding equation equivalent to the de Broglie–Bohm one. •Proving the absence of third order interferences and thus explaining Born’s rule. •Explaining the violation of Sorkin’s order sum rules. •Classical simulation of Talbot

The Role(s) of Heparan Sulfate Proteoglycan(s) in the wnt-1 Signaling Pathway

DTIC Science & Technology

1998-08-01

First , the sequence of the cDNA, when compared to the genomic site of insertion of the P-element, revealed that the P-element is inserted 686 bp...stages 8 to 13 (Yoffe et al. 1995). We first examined whether ectopic expression of Wgts effectively restores the naked cuticle as it does in wg and...by Kjell~n and Lindahl, 1991) . HS/heparin N-deacetylase/N-sulfotransferase catalyzes N-deacetylation and N-sulfation that is the first and key step

Biological Sciences and Bioelectromagnetics in Europe: Summary Report.

DTIC Science & Technology

1985-08-26

shielded room in which the Madrid study. This project, dubbed "Pro- Earth’s magnetic field has been removed , Ject Henhouse," involves the original they...investi- the patients are removed from the room gator), a laboratory in Sweden (Dr. and returned to their normal environ- KJell Mild), and two...a little far removed of the samples were sent to them by mail and is certainly an area that needs more and had a reduced proliferation rate. It work

Photocopy of postcard (original in Picture Group 800, Connecticut State ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photocopy of postcard (original in Picture Group 800, Connecticut State Library, Hartford, Connecticut), C.G. Talbot, publisher, Putnam, Conn., No. 1478. Postmarked 1905. Grammar School, Putnam, Conn. - Israel Putnam School, School & Oak Streets, Putnam, Windham County, CT

Change of Command ceremony

NASA Image and Video Library

2015-09-05

ISS044E086857 (09/05/2015) --- Cosmonaut Gennady Padalka (center in red shirt) handed command of the International Space Station to NASA astronaut Scott Kelly (front left with microphone) on Sept. 5, 2015. In the background the rest of the space station crew was on hand (from left to right): ESA(European Space Agency) astronaut Andreas Mogensen (back), Russian cosmonauts Mikhail Kornienko, Sergey Volkov and Oleg Kononenko, Kazakh cosmonaut Aidyn Aimbetov, Japan Aerospace Exploration Agency (JAXA) astronaut Kimiya Yui and NASA astronaut Kjell Lindgren.

View of Kelly outside the A/L during EVA 32

NASA Image and Video Library

2015-10-28

ISS045E082968 (10/28/2015) --- NASA astronaut Scott Kelly is photographed just outside the airlock during his first ever spacewalk on Oct 28, 2015. Kelly and NASA astronaut Kjell Lindgren worked outside for seven hours and 16 minutes on a series of tasks to service and upgrade the International Space Station. They wrapped a dark matter detection experiment in a thermal blanket, lubricated the tip of the Canadarm2 robotic arm and then routed power and data cables for a future docking port.

Kelly takes a Self-Portrait during EVA 32

NASA Image and Video Library

2015-10-28

ISS045E082998 (10/28/2015) --- NASA astronaut Scott Kelly snaps a quick space selfie during his first ever spacewalk on Oct 28, 2015. Kelly and NASA astronaut Kjell Lindgren worked outside for seven hours and 16 minutes on a series of tasks to service and upgrade the International Space Station. They wrapped a dark matter detection experiment in a thermal blanket, lubricated the tip of the Canadarm2 robotic arm and then routed power and data cables for a future docking port.

1. Photocopy of photograph (original print located in Pope & ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of photograph (original print located in Pope & Talbot Archives. Port Gamble, WA.) Unknown Photographer, Unknown Date. View of Walker-Ames House, house no. 1, facing southwest. - Walker-Ames House, Rainier Avenue, Port Gamble, Kitsap County, WA

2. Historic American Buildings Survey E.H. Pickering, Photographer December 1936 ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Historic American Buildings Survey E.H. Pickering, Photographer December 1936 OLDEST FRAME HOUSE OF WORSHIP IN MARYLAND. LORD AND LADY BALTIMORE ATTENDED SERVICE HERE IN 1700 WHEN WM. PENN PREACHED. - Quaker Meetinghouse, Washington Street, Easton, Talbot County, MD

1. Photocopy of photograph (original print #17 located in ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of photograph (original print #17 - located in Pope & Talbot Archives. Port Gamble, WA). Unknown Photographer, September 1906. View of St. Paul's Episcopal Church, facing southwest from Rainier Avenue. - St. Paul's Episcopal Church, Rainier Avenue, Port Gamble, Kitsap County, WA

Lindgren during EVA 32

NASA Image and Video Library

2015-10-28

ISS045E082789 (10/28/2015) --- NASA astronaut Kjell Lindgren is photographed through a window during a night pass while on his first spacewalk on Oct. 28, 2015. Lindgren and NASA astronaut Scott Kelly worked outside for seven hours and 16 minutes on a series of tasks to service and upgrade the International Space Station. They wrapped a dark matter detection experiment in a thermal blanket, lubricated the tip of the Canadarm2 robotic arm and then routed power and data cables for a future docking port.

A new optical post-equalization based on self-imaging

NASA Astrophysics Data System (ADS)

Guizani, S.; Cheriti, A.; Razzak, M.; Boulslimani, Y.; Hamam, H.

2005-09-01

Driven by the world's growing need for communication bandwidth, progress is constantly being reported in building newer fibers that are capable of handling the rapid increase in traffic. However, building an optical fiber link is a major investment, one that is very expensive to replace. A major impairment that restricts the achievement of higher bit rates with standard single mode fiber is chromatic dispersion. This is particularly problematic for systems operating in the 1550 nm band, where the chromatic dispersion limit decreases rapidly in inverse proportion to the square of the bit rate. For the first time, to the best of our knowledge, this document illustrates a new optical technique to post compensate optically the chromatic dispersion in fiber using temporal Talbot effect in ranges exceeding the 40G bit/s. We propose a new optical post equalization solutions based on the self imaging of Talbot effect.

Phase-space evolution of x-ray coherence in phase-sensitive imaging.

PubMed

Wu, Xizeng; Liu, Hong

2008-08-01

X-ray coherence evolution in the imaging process plays a key role for x-ray phase-sensitive imaging. In this work we present a phase-space formulation for the phase-sensitive imaging. The theory is reformulated in terms of the cross-spectral density and associated Wigner distribution. The phase-space formulation enables an explicit and quantitative account of partial coherence effects on phase-sensitive imaging. The presented formulas for x-ray spectral density at the detector can be used for performing accurate phase retrieval and optimizing the phase-contrast visibility. The concept of phase-space shearing length derived from this phase-space formulation clarifies the spatial coherence requirement for phase-sensitive imaging with incoherent sources. The theory has been applied to x-ray Talbot interferometric imaging as well. The peak coherence condition derived reveals new insights into three-grating-based Talbot-interferometric imaging and gratings-based x-ray dark-field imaging.

X-ray Optics Testing Beamline 1-BM at the Advanced Photon Source

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

Macrander, Albert; Erdmann, Mark; Kujala, Naresh

2016-07-27

Beamline 1-BM at the APS has been reconfigured in part for testing of synchrotron optics with both monochromatic and white beams. Operational since 2013, it was reconfigured to accommodate users of the APS as well as users from other DOE facilities. Energies between 6 and 28 keV are available. The beamline was reconfigured to remove two large mirrors and to provide a 100 mm wide monochromatics beam at 54 m from the source. In addition a custom white beam shutter was implemented for topography exposures as short as 65 millisec over the full available horizontal width. Primary agendas include bothmore » white beam and monochromatic beam topography, Talbot grating interferometry, and tests of focusing optics. K-B mirrors, MLLs, and FZPs have been characterized. Measurements of the spatial coherence lengths on the beamline were obtained with Talbot interferometry. Topography data has been reported.« less

X-ray optics testing beamline 1-BM at the advanced photon source

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

Macrander, Albert, E-mail: atm@anl.gov; Erdmann, Mark; Kujala, Naresh

2016-07-27

Beamline 1-BM at the APS has been reconfigured in part for testing of synchrotron optics with both monochromatic and white beams. Operational since 2013, it was reconfigured to accommodate users of the APS as well as users from other DOE facilities. Energies between 6 and 28 keV are available. The beamline was reconfigured to remove two large mirrors and to provide a 100 mm wide monochromatic beam at 54 m from the source. In addition a custom white beam shutter was implemented for topography exposures as short as 65 millisec over the full available horizontal width. Primary agendas include bothmore » white beam and monochromatic beam topography, Talbot grating interferometry, and tests of focusing optics. K-B mirrors, MLLs, and FZPs have been characterized. Measurements of the spatial coherence lengths on the beamline were obtained with Talbot interferometry. Topography data has been reported.« less

Rehabilitation: 25 Years of Concepts, Principles, Perspectives. A Collection of Articles Published in "Rehabilitation Literature," 1959-1984.

ERIC Educational Resources Information Center

Regnier, Stephen J., Comp.; Petkovsek, Marian, Comp.

Twenty-five articles from the bimonthly journal "Rehabilitation Literature" (1959-1984) are presented. The articles were chosen to represent key concepts, principles, and perspectives in rehabilitation. The following authors and titles are represented: "A Concept of Rehabilitation" (H. Talbot); "Rehabilitation: Prospect and Retrospect" (H.…

From the Proton Synchroton to the Large Hadron Collider - 50 Years of Nobel Memories in High-Energy Physics

ScienceCinema

None

2018-06-19

The seminars will be held in the Main Auditorium with transmission to : Council Chamber, IT Auditorium, Prévessin BE Auditorium , Kjell Johnssen Auditorium in Building 30, Room 40-S2-A01, and via webcast. Confirmed Speakers include: Prof. Jack Steinberger, Dr. Guenther Plass, Prof. Emilio Picasso, Dr. Steve Myers, Prof. Carlo Rubbia, Prof. Burton Richter, Dr. Lyndon Evans, Prof. Rolf-Dieter Heuer, Prof. Leon Lederman, Prof. Jim Cronin, Prof. Sheldon Glashow, Prof. Jerome Friedman, Prof. Frank Wilczek, Prof. Martinus Veltman, Prof. Gerardus 't Hooft, Prof. David Gross, Prof. Samuel Ting, Prof. Steven Weinberg (via teleconference) --- Contact: Directorate.Office@cern.ch

From the Proton Synchroton to the Large Hadron Collider - 50 Years of Nobel Memories in High-Energy Physics

ScienceCinema

Friedman, Jerome

2018-06-15

The seminars will be held in the Main Auditorium with transmission to : Council Chamber, IT Auditorium, Prévessin BE Auditorium , Kjell Johnssen Auditorium in Building 30, Room 40-S2-A01, and via webcast. Confirmed Speakers include: Prof. Jack Steinberger, Dr. Guenther Plass, Prof. Emilio Picasso, Dr. Steve Myers, Prof. Carlo Rubbia, Prof. Burton Richter, Dr. Lyndon Evans, Prof. Rolf-Dieter Heuer, Prof. Leon Lederman, Prof. Jim Cronin, Prof. Sheldon Glashow, Prof. Jerome Friedman, Prof. Frank Wilczek, Prof. Martinus Veltman, Prof. Gerardus 't Hooft, Prof. David Gross, Prof. Samuel Ting, Prof. Steven Weinberg (via teleconference) --- Contact: Directorate.Office@cern.ch

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

None

The seminars will be held in the Main Auditorium with transmission to : Council Chamber, IT Auditorium, Prévessin BE Auditorium , Kjell Johnssen Auditorium in Building 30, Room 40-S2-A01, and via webcast. Confirmed Speakers include: Prof. Jack Steinberger, Dr. Guenther Plass, Prof. Emilio Picasso, Dr. Steve Myers, Prof. Carlo Rubbia, Prof. Burton Richter, Dr. Lyndon Evans, Prof. Rolf-Dieter Heuer, Prof. Leon Lederman, Prof. Jim Cronin, Prof. Sheldon Glashow, Prof. Jerome Friedman, Prof. Frank Wilczek, Prof. Martinus Veltman, Prof. Gerardus 't Hooft, Prof. David Gross, Prof. Samuel Ting, Prof. Steven Weinberg (via teleconference) --- Contact: Directorate.Office@cern.ch

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

None

The seminars will be held in the Main Auditorium with transmission to: Council Chamber, IT Auditorium, Prévessin BE Auditorium , Kjell Johnssen Auditorium in Building 30, Room 40-S2-A01, and via webcast. Confirmed Speakers include: Prof. Jack Steinberger, Dr. Guenther Plass, Prof. Emilio Picasso, Dr. Steve Myers, Prof. Carlo Rubbia, Prof. Burton Richter, Dr. Lyndon Evans, Prof. Rolf-Dieter Heuer, Prof. Leon Lederman, Prof. Jim Cronin, Prof. Sheldon Glashow, Prof. Jerome Friedman, Prof. Frank Wilczek, Prof. Martinus Veltman, Prof. Gerardus 't Hooft, Prof. David Gross, Prof. Samuel Ting, Prof. Steven Weinberg (via teleconference) --- Contact: Directorate.Office@cern.ch

Retraction: Borroto-Escuela et al., The existence of FGFR1-5-HT1A receptor heterocomplexes in midbrain 5-HT neurons of the rat: relevance for neuroplasticity.

PubMed

2013-07-10

The Journal of Neuroscience has received a report describing an investigation by the Karolinska Institutet, which found substantial data misrepresentation in the article "The Existence of FGFR1-5-HT1A Receptor Heterocomplexes in Midbrain 5-HT Neurons of the Rat: Relevance for Neuroplasticity" by Dasiel O. Borroto-Escuela, Wilber Romero-Fernandez, Mileidys Pérez-Alea, Manuel Narvaez, Alexander O. Tarakanov, Giuseppa Mudó , Luigi F. Agnati, Francisco Ciruela, Natale Belluardo, and Kjell Fuxe, which appeared on pages 6295-6303 of the May 2, 2012 issue. Because the results cannot be considered reliable, the editors of The Journal are retracting the paper.

Space Station Astronauts Return Safely to Earth on This Week @NASA – December 11, 2015

NASA Image and Video Library

2015-12-11

On Dec. 11 aboard the International Space Station, NASA’s Kjell Lindgren, Russian cosmonaut Oleg Kononenko and Kimiya Yui of the Japan Aerospace Exploration Agency, bid farewell to crew members remaining on the station -- including Commander Scott Kelly, NASA’s one-year mission astronaut. The returning members of Expedition 45 then climbed aboard their Soyuz spacecraft for the trip back to Earth. They safely touched down hours later in Kazakhstan – closing out a 141-day stay in space. Also, Next space station crew prepares for launch, Supply mission arrives at space station, Quantum computing lab and more!

From the Proton Synchroton to the Large Hadron Collider - 50 Years of Nobel Memories in High-Energy Physics

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

None

2009-12-07

The seminars will be held in the Main Auditorium with transmission to : Council Chamber, IT Auditorium, Prévessin BE Auditorium , Kjell Johnssen Auditorium in Building 30, Room 40-S2-A01, and via webcast. Confirmed Speakers include: Prof. Jack Steinberger, Dr. Guenther Plass, Prof. Emilio Picasso, Dr. Steve Myers, Prof. Carlo Rubbia, Prof. Burton Richter, Dr. Lyndon Evans, Prof. Rolf-Dieter Heuer, Prof. Leon Lederman, Prof. Jim Cronin, Prof. Sheldon Glashow, Prof. Jerome Friedman, Prof. Frank Wilczek, Prof. Martinus Veltman, Prof. Gerardus 't Hooft, Prof. David Gross, Prof. Samuel Ting, Prof. Steven Weinberg (via teleconference) --- Contact: Directorate.Office@cern.ch

From the Proton Synchroton to the Large Hadron Collider - 50 Years of Nobel Memories in High-Energy Physics

ScienceCinema

None

2017-12-09

The seminars will be held in the Main Auditorium with transmission to : Council Chamber, IT Auditorium, Prévessin BE Auditorium , Kjell Johnssen Auditorium in Building 30, Room 40-S2-A01, and via webcast. Confirmed Speakers include: Prof. Jack Steinberger, Dr. Guenther Plass, Prof. Emilio Picasso, Dr. Steve Myers, Prof. Carlo Rubbia, Prof. Burton Richter, Dr. Lyndon Evans, Prof. Rolf-Dieter Heuer, Prof. Leon Lederman, Prof. Jim Cronin, Prof. Sheldon Glashow, Prof. Jerome Friedman, Prof. Frank Wilczek, Prof. Martinus Veltman, Prof. Gerardus 't Hooft, Prof. David Gross, Prof. Samuel Ting, Prof. Steven Weinberg (via teleconference) --- Contact: Directorate.Office@cern.ch

78 FR 70027 - Senior Executive Service; Performance Review Board

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-22

.... SYKES, MERLE L. SYNAKOWSKI, EDMUND J. TALBOT JR, GERALD L. TAYLOR, CHARLES W. THOMPSON, MICHAEL A..., WILLIAM N. BURROWS, CHARLES W. BUTTRESS, LARRY D. CADIEUX, GENA E. CALBOS, PHILIP T. CALLAHAN, SAMUEL N..., JAMES MELBOURN DURANT, CHARLES K. ECKROADE, WILLIAM A. EDWARDS III, ROBERT E. EHLI, CATHY L. ELKIND...

The Relationship between Lattice Enthalpy and Melting Point in Magnesium and Aluminium Oxides. Science Notes

ERIC Educational Resources Information Center

Talbot, Christopher; Yap, Lydia

2013-01-01

This "Science Note" presents a study by Christopher Talbot and Lydia Yap, who teach IB Chemistry at Anglo-Chinese School (Independent), Republic of Singapore, to pre-university students. Pre-university students may postulate the correlation between the magnitude of the lattice enthalpy compound and its melting point, since both…

The Effect of Leader Attributes, Situational Context, and Participant Optimism on Trust in Outdoor Leaders

ERIC Educational Resources Information Center

Shooter, Wynn; Paisley, Karen; Sibthorp, Jim

2009-01-01

Outdoor education researchers have accumulated a notable cache of work documenting the outcomes of participation in outdoor education programs (e.g., Hattie, Marsh, Neill, & Richards, 1997; Kaplan & Talbot, 1983). While continuing this work remains an important task, some researchers are turning their attention toward understanding the process of…

Building a MicroSociety

ERIC Educational Resources Information Center

Dunton, Sheryl

2006-01-01

Talbot Hill Elementary School in Renton, Washington, uses the MicroSociety model to make learning relevant and engaging for its diverse student population. Three afternoons each week, every student participates in a for-profit business, a governmental agency, or a nonprofit organization. Teachers prepare students to participate in the school's…

From Matron to Maven: A New Role and New Professional Identity for Deans of Women, 1892 to 1916.

ERIC Educational Resources Information Center

Nidiffer, Jana

1995-01-01

Traces the careers of four women who were instrumental in transforming the position of dean of women from dormitory matron into professional administrator. These women were Marion Talbot, University of Chicago, 1892-1925; Mary Bidwell Breed, Indiana University, 1901-06; Ada Louise Comstock, University of Minnesota, 1906-12; and Lois Kimball…

Fabrication and Characterization of Tilted Fiber Optic Bragg Grating Filters over Various Wavelengths

NASA Technical Reports Server (NTRS)

Grant, Joseph; Jackson, Kurt V.; Wang, Y.; Sharma, A.; Burdine, Robert V. (Technical Monitor)

2002-01-01

Fiber Optic Bragg Grating taps are fabricated and characterized at various wavelengths using a modified Talbot interferometric technique. Gratings are fabricated by tilting the photosensitive fiber to angles up to 45 degrees w.r.t. the writing angle. Diffraction characteristics of the tilted grating is monitored in first and second orders.

Groundwater-Discharge Wetlands in the Tanana Flats, Interior Alaska

DTIC Science & Technology

1991-07-01

Water *Hemlock Duckweed Bladderwort Bcba Cal a Floating Mat Water 9112214 0 1im For conversion of SI metric units to U.S./British customary units of...Utricularia sp.) and duckweed (Lemna sp,.). classified as "fens" (Gabriel and Talbot 1984). There Mosses do not appear to contribute to the structure

Instructional Resources. The Significance of Form: The Architecture of Public Buildings.

ERIC Educational Resources Information Center

Talbot-Stanaway, Susan; And Others

1989-01-01

Presents the architecture of public buildings through a set of four lessons. (S. Talbot-Stanaway and Elizabeth Hornor). The lessons teach about the Oshkosh Grand Opera House in Oshkosh, Wisconsin; the Clayton County Library in Jonesboro, Georgia; the Pennsylvania Academy of the Fine Arts in Philadelphia, Pennsylvania; and the National Gallery of…

Demystifying the Halftoning Process: Conventional, Stochastic, and Hybrid Halftone Dot Structures

ERIC Educational Resources Information Center

Oliver, Garth R.; Waite, Jerry J.

2006-01-01

For more than 150 years, printers have been faithfully reproducing continuous tone originals using halftoning techniques. For about 120 years, printers could only use the AM halftoning technique invented by Henry Talbot. In recent years, the advent of powerful raster image processors and high-resolution output devices has increased the variety of…

NCI at Frederick's Wye Oak Moves Down the Street | Poster

Cancer.gov

One of NCI at Frederick’s two offspring of the Wye Oak tree that lived for nearly 500 years in Talbot County, Maryland, has found a new home on campus. The move was necessitated by upgrades to Chiller Plant #5 and the associated water piping routes on the west side of building 560.

An Investigation into the Creation, Stability, and X-Ray Fluorescence Analysis of Early Photographic Processes: An Upper-Level Undergraduate Laboratory

ERIC Educational Resources Information Center

Rogge, Corina E.; Bezur, Aniko

2012-01-01

Photography is one of the few fine art forms that were initially developed by scientists such as Herschel and Talbot; however, in the modern chemistry curriculum, photography has become divorced from its scientific beginnings and resides in the studio arts department of most universities. An upper-level undergraduate experiment is described in…

Investigating biofilm structure using x-ray microtomography and gratings-based phase contrast

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

Miller, Erin A.; Xiao, Xianghui; Miller, Micah D.

2012-10-17

Direct examination of natural and engineered environments has revealed that the majority of microorganisms in these systems live in structured communities termed biofilms. To gain a better understanding for how biofilms function and interact with their local environment, fundamental capabilities for enhanced visualization, compositional analysis, and functional characterization of biofilms are needed. For pore-scale and community-scale analysis (100’s of nm to 10’s of microns), a variety of surface tools are available. However, understanding biofilm structure in complex three-dimensional (3-D) environments is considerably more difficult. X-ray microtomography can reveal a biofilm’s internal structure, but the obtaining sufficient contrast to image low-Zmore » biological material against a higher-Z substrate makes detecting biofilms difficult. Here we present results imaging Shewanella oneidensis biofilms on a Hollow-fiber Membrane Biofilm Reactor (HfMBR), using the x-ray microtomography system at sector 2-BM of the Advanced Photon Source (APS), at energies ranging from 13-15.4 keV and pixel sizes of 0.7 and 1.3 μm/pixel. We examine the use of osmium (Os) as a contrast agent to enhance biofilm visibility and demonstrate that staining improves imaging of hydrated biofilms. We also present results using a Talbot interferometer to provide phase and scatter contrast information in addition to absorption. Talbot interferometry allows imaging of unstained hydrated biofilms with phase contrast, while absorption contrast primarily highlights edges and scatter contrast provides little information. However, the gratings used here limit the spatial resolution to no finer than 2 μm, which hinders the ability to detect small features. Future studies at higher resolution or higher Talbot order for greater sensitivity to density variations may improve imaging.« less

Pioneering Deans of Women: More Than Wise and Pious Matrons. Athene Series.

ERIC Educational Resources Information Center

Nidiffer, Jana

This book examines the careers and contributions of four pioneering deans of women and the innovations they created as they worked to enhance opportunities and community for women. The women are Marion Talbot, Mary Bidwell Breed, Ada Louise Comstock, and Lois Kimball Mathews. The book analyzes how they developed a profession out of their…

Linear information retrieval method in X-ray grating-based phase contrast imaging and its interchangeability with tomographic reconstruction

NASA Astrophysics Data System (ADS)

Wu, Z.; Gao, K.; Wang, Z. L.; Shao, Q. G.; Hu, R. F.; Wei, C. X.; Zan, G. B.; Wali, F.; Luo, R. H.; Zhu, P. P.; Tian, Y. C.

2017-06-01

In X-ray grating-based phase contrast imaging, information retrieval is necessary for quantitative research, especially for phase tomography. However, numerous and repetitive processes have to be performed for tomographic reconstruction. In this paper, we report a novel information retrieval method, which enables retrieving phase and absorption information by means of a linear combination of two mutually conjugate images. Thanks to the distributive law of the multiplication as well as the commutative law and associative law of the addition, the information retrieval can be performed after tomographic reconstruction, thus simplifying the information retrieval procedure dramatically. The theoretical model of this method is established in both parallel beam geometry for Talbot interferometer and fan beam geometry for Talbot-Lau interferometer. Numerical experiments are also performed to confirm the feasibility and validity of the proposed method. In addition, we discuss its possibility in cone beam geometry and its advantages compared with other methods. Moreover, this method can also be employed in other differential phase contrast imaging methods, such as diffraction enhanced imaging, non-interferometric imaging, and edge illumination.

Kelly and Lindgren conduct EMU Resize OPS

NASA Image and Video Library

2015-10-07

ISS045E050652 (10/07/2015) --- US astronauts Scott Kelly (bottom)and Kjell Lindgren (top) are counting down to a pair of spacewalks, now targeted for Oct. 28 and Nov. 6. The duo serviced their spacesuits replacing lithium batteries, checking their gloves and verifying power to video cameras. On the first spacewalk, the spacewalkers will lubricate the tip of the robotic arm Canadarm2, route power cables and place a thermal shroud over the Alpha Magnetic Spectrometer. During the second spacewalk, Kelly and Lindgren will refill coolant reservoirs and configure the port truss cooling system back to its original configuration after repair work completed back in 2012.

Sal Adelante Mujer!: Support Group for Latina First-Year College Students

ERIC Educational Resources Information Center

Segura-Malady, Evelyn E.

2014-01-01

Latinas are at a disadvantage when it comes to earning a college degree, as is evidenced by the fact that they take longer to complete their degrees than Black, Asian, and white college students and have the lowest graduation rates in comparison to these respective groups (Fry, 2004; Fry, 2012; Rodriguez, Guido-Brito, Torres, & Talbot, 2000).…

1. Photocopy of photograph (original print located in Pope & ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of photograph (original print located in Pope & Talbot Archives Port Gamble, WA). Unknown Photographer, 1907. View of Gamble Bay, facing west from east shore. S'klallam Village of Boston in foreground, Puget Mill in background. - Port Gamble National Historic Landmark, Bounded by Hood Canal, Port Gamble Bay, State Road 104, & Town Limits, Port Gamble, Kitsap County, WA

75 FR 77660 - National Register of Historic Places; Notification of Pending Nominations and Related Actions

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-13

...--Proctor House, 133 First Ave, Twin City, 10001049 MARYLAND Talbot County Miller's House, Old Wye Mills Rd... Lincoln County Lincoln Hotel, 301 W Sherlock St, Harrington, 10001044 Skagit County Northern State Hospital, Roughly bounded by Thompson Dr to the S, Hemlick Dr to the E, Hub Dr to the W, and \\1/4\\ mi S of...

78 FR 32556 - Safety Zone; 2013 Ocean City Air Show, Atlantic Ocean; Ocean City, MD

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-31

...-AA00 Safety Zone; 2013 Ocean City Air Show, Atlantic Ocean; Ocean City, MD AGENCY: Coast Guard, DHS... navigable waters of the Atlantic Ocean in the vicinity of Ocean City, MD to support the Ocean City Air Show... June 9, 2013, Ocean City, MD will host an air show event between Talbot Street and 33rd Street over the...

75 FR 18778 - Safety Zone; Ocean City Air Show 2010, Atlantic Ocean, Ocean City, MD

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-13

...-AA00 Safety Zone; Ocean City Air Show 2010, Atlantic Ocean, Ocean City, MD AGENCY: Coast Guard, DHS... zone on the Atlantic Ocean in the vicinity of Ocean City, Maryland to support the Ocean City Air Show..., 5, and 6, 2010 Ocean City, Maryland will host an air show event on the Atlantic Ocean between Talbot...

Description of two new Jujubinus species (Gastropoda: Trochidae) from the Sicily Channel, with notes on the Jujubinus curinii species complex.

PubMed

Smriglio, Carlo; Di Giulio, Andrea; Mariottini, Paolo

2014-06-17

Based on shell characters, two new species of the gastropod family Trochidae, Jujubinus eleonorae n. sp. and Jujubinus trilloi n. sp., from the Sicily Channel are described. Shells of the new taxa were collected in the lower infralittoral of the Skerki and Talbot Banks, respectively. The new taxa are compared with Jujubinus curinii Bogi & Campani, 2005, morphologically the most closely related species.

US-Europe Workshop on Impact of Multifunctionality on Damage Evolution in Composite Materials

DTIC Science & Technology

2015-09-01

Inventions (DD882) Scientific Progress See Attachment Technology Transfer Not applicable UNIVERSITY OF ILLINOIS AEROSPACE ENGINEERING...Composite Materials PI: Ioannis Chasiotis Aerospace Engineering University of Illinois at Urbana-Champaign Talbot Lab, 104 S. Wright Street, Urbana, IL...focused on the current state of corporate research in the aerospace industry which is a major potential adopter of multifunctional composites. The two

Using optical masks to create and image sub-optical wavelength atomic structures in a MOT

NASA Astrophysics Data System (ADS)

Turlapov, Andrey; Tonyushkin, Aleksey; Sleator, Tycho

2002-05-01

We have used an ``optical mask'' for Rubidium atoms in a magneto-optical trap to create and image atomic density gratings with periodicities as small as 1/8th of an optical wavelength ( ˜ 100 nm). The mask consists of a pulse of an optical standing wave (wavelength λ) resonant to an open atomic transition. The interaction pumps all atoms except those near the nodes into another hyperfine ground state, leaving a grating of ``spikes'' in atomic density in the initial ground state. The nodes of the standing wave serve as slits of the mask. By applying two such masks separated by time T, we have created atomic gratings of period λ/(2n) (or smaller) at times (n+1)/n T after the first mask pulse. For T on the order of the Talbot time (or inverse recoil frequency), quantum effects are important for the dynamics of the atomic center of mass. Under appropriate conditions, these quantum effects led to a reduction of the period of the resulting density gratings (Talbot-Lau effect). The resulting density gratings of period λ/2n (for n=1 to 4) were imaged in real time using an additional optical mask.

Talbot self-imaging phenomenon under Bessel beam illumination

NASA Astrophysics Data System (ADS)

Chakraborty, Rijuparna; Chowdhury, Subhajit Dutta; Chakraborty, Ajoy Kumar

2018-06-01

In this paper, we report the results of our theoretical studies on the phenomenon of self-imaging of periodic object under the illumination of zero-order Bessel beam. Our theoretical analysis indicates that the self-images are visible only after the walk-off distance of the Bessel beam used. It is also observed that the self-images bend around the optical axis of the setup. Besides, the present study justifies the importance of the conditions stipulated by Montgomery.

2. Photocopy of photograph (original print located in Pope & ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Photocopy of photograph (original print located in Pope & Talbot Archives Port Gamble, WA). Unknown Photographer, Circa 1953. View of Port Gamble and surroundings, aerial shot facing west. Port Gamble Bay, townsite and millsite in foreground, Hood Canal and Olympic Mountains in the background. - Port Gamble National Historic Landmark, Bounded by Hood Canal, Port Gamble Bay, State Road 104, & Town Limits, Port Gamble, Kitsap County, WA

46 CFR 7.90 - St. Johns River, FL.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false St. Johns River, FL. 7.90 Section 7.90 Shipping COAST... § 7.90 St. Johns River, FL. A line drawn from the southeasternmost extremity of Little Talbot (Spike) Island to latitude 30°23.8′ N. longitude 81°20.3′ W. (St. Johns Lighted Whistle Buoy “2 STJ”); thence to...

18 CFR Appendix A to Part 11 - FEE SCHEDULE FOR FY 2014

Code of Federal Regulations, 2014 CFR

2014-04-01

... Jasper 103.15 Jeff Davis 59.93 Jefferson 57.77 Jenkins 51.51 Johnson 52.91 Jones 95.72 Lamar 112.02... 62.96 Talbot 56.81 Taliaferro 70.44 Tattnall 74.93 Taylor 57.72 Telfair 60.79 Terrell 63.93 Thomas 73... Stevens 22.10 Sumner 26.24 Thomas 22.86 Trego 17.29 Wabaunsee 27.28 Wallace 17.43 Washington 28.93 Wichita...

Some doctors of medicine who published optometry books and played significant roles in early twentieth century optometric education.

PubMed

Goss, David A

2011-01-01

This paper provides brief profiles of four doctors of medicine who wrote books for optometrists and who were faculty members in, and/or directors of, optometry schools in the early twentieth century. Those studied were Thomas G. Atkinson (1870-1946), Marshall B. Ketchum (1856-1937), Joseph I. Pascal (1890-1955), and Clarence W. Talbot (1883-1958). The content of the books they wrote is also discussed.

Multisite study of particle number concentrations in urban air.

PubMed

Harrison, Roy M; Jones, Alan M

2005-08-15

Particle number concentration data are reported from a total of eight urban site locations in the United Kingdom. Of these, six are central urban background sites, while one is an urban street canyon (Marylebone Road) and another is influenced by both a motorway and a steelworks (Port Talbot). The concentrations are generally of a similar order to those reported in the literature, although higher than those in some of the other studies. Highest concentrations are at the Marylebone Road site and lowest are at the Port Talbot site. The central urban background locations lie somewhere between with concentrations typically around 20 000 cm(-3). A seasonal pattern affects all sites, with highest concentrations in the winter months and lowest concentrations in the summer. Data from all sites show a diurnal variation with a morning rush hour peak typical of an anthropogenic pollutant. When the dilution effects of windspeed are accounted for, the data show little directionality at the central urban background sites indicating the influence of sources from all directions as might be expected if the major source were road traffic. At the London Marylebone Road site there is high directionality driven by the air circulation in the street canyon, and at the Port Talbot site different diurnal patterns are seen for particle number count and PM10 influenced by emissions from road traffic (particle number count) and the steelworks (PM10) and local meteorological factors. Hourly particle number concentrations are generally only weakly correlated to NO(x) and PM10, with the former showing a slightly closer relationship. Correlations between daily average particle number count and PM10 were also weak. Episodes of high PM10 concentration in summer typically show low particle number concentrations consistent with transport of accumulation mode secondary aerosol, while winter episodes are frequently associated with high PM10 and particle number count arising from poor dispersion of

Kashmir--The Key to Peace in Afghanistan

DTIC Science & Technology

2013-03-01

Missile Crisis the U.S. had to learn similar lessons in the early years of it gaining nuclear weapons. Victoria Schofield and Praveen Swami reinforce...12 Praveen Swami, India, Pakistan and the Secret Jihad (London: Routledge, 2007), 204. 13 Peter Lavoy, Asymmetric Warefare in South Asia: the...Swami, Praveen . India, Pakistan and the Secret Jihad. London: Routledge, 2007. Talbot, Ian. Pakistan: A Modern History. New Delhi: Oxford University

Space Station Astronauts Make Safe Landing on This Week @NASA – September 11, 2015

NASA Image and Video Library

2015-09-11

Aboard the International Space Station, the Expedition 45 crew – including new Commander Scott Kelly and Kjell Lindgren of NASA, said goodbye to Gennady Padalka of the Russian Federal Space Agency, Andreas Mogensen of ESA (European Space Agency) and Aidyn Aimbetov of the Kazakh Space Agency (Kazcosmos) as the trio climbed aboard their Soyuz spacecraft for the return trip to Earth. The Soyuz landed safely in Kazakhstan on Sept. 11 Eastern time, Sept. 12 in Kazakhstan -- closing out a 168-day mission for Padalka and an 8-day stay on the station for Mogensen and Aimbetov. Also, First Orion crew module segments welded, SLS Launch Vehicle Stage Adapter, New Ceres imagery, New Horizons update, 9/11 tribute and National Preparedness Month!

X-ray phase-contrast computed tomography visualizes the microstructure and degradation profile of implanted biodegradable scaffolds after spinal cord injury

PubMed Central

Takashima, Kenta; Hoshino, Masato; Uesugi, Kentaro; Yagi, Naoto; Matsuda, Shojiro; Nakahira, Atsushi; Osumi, Noriko; Kohzuki, Masahiro; Onodera, Hiroshi

2015-01-01

Tissue engineering strategies for spinal cord repair are a primary focus of translational medicine after spinal cord injury (SCI). Many tissue engineering strategies employ three-dimensional scaffolds, which are made of biodegradable materials and have microstructure incorporated with viable cells and bioactive molecules to promote new tissue generation and functional recovery after SCI. It is therefore important to develop an imaging system that visualizes both the microstructure of three-dimensional scaffolds and their degradation process after SCI. Here, X-ray phase-contrast computed tomography imaging based on the Talbot grating interferometer is described and it is shown how it can visualize the polyglycolic acid scaffold, including its microfibres, after implantation into the injured spinal cord. Furthermore, X-ray phase-contrast computed tomography images revealed that degradation occurred from the end to the centre of the braided scaffold in the 28 days after implantation into the injured spinal cord. The present report provides the first demonstration of an imaging technique that visualizes both the microstructure and degradation of biodegradable scaffolds in SCI research. X-ray phase-contrast imaging based on the Talbot grating interferometer is a versatile technique that can be used for a broad range of preclinical applications in tissue engineering strategies. PMID:25537600

The Wye Oaks on Campus | Poster

Cancer.gov

The Wye Oak tree—a towering white oak that lived for nearly 500 years in Talbot County, Maryland—was the nation’s largest white oak tree as well as the State Tree of Maryland until it was destroyed in a severe thunderstorm in 2002. Today, several clones of the Wye Oak, as well as a few of the Wye Oak’s progeny, still exist—including two on the NCI at Frederick campus.

Comparison of different phase retrieval algorithms

NASA Astrophysics Data System (ADS)

Kaufmann, Rolf; Plamondon, Mathieu; Hofmann, Jürgen; Neels, Antonia

2017-09-01

X-ray phase contrast imaging is attracting more and more interest. Since the phase cannot be measured directly an indirect method using e.g. a grating interferometer has to be applied. This contribution compares three different approaches to calculate the phase from Talbot-Lau interferometer measurements using a phase-stepping approach. Besides the usually applied Fourier coefficient method also a linear fitting technique and Taylor series expansion method are applied and compared.

3. View of Port Gamble commercial district, facing south from ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. View of Port Gamble commercial district, facing south from intersection of Rainier Avenue with Walker Street. Pope and Talbot office and general store building in left foreground, Walker-Ames House in left background. Community Hall in right foreground, masonic lodge in right background, fire station between hall and lodge. - Port Gamble National Historic Landmark, Bounded by Hood Canal, Port Gamble Bay, State Road 104, & Town Limits, Port Gamble, Kitsap County, WA

Flow in Curved Ducts of Varying Cross-Section

DTIC Science & Technology

1992-07-01

56 IX.2 900 pipe bend of Enayet et al. (1983) ............................. 57 IX.3 1800 pipe bend of Rowe (1970...et al. (1978), Chandran et al. (1979, 1981), Enayet et al. (1982b), Talbot and Gong (1983), Bovendeerd et al. (1987) and Rindt et al. (1991). There are...Bruun (1979), Humphrey et al. (1981), Taylor et al. (1982), Enayet et al. (1982a), Chang (1983), lacovides et al. (1990) and Kim (1991). The early works

West Europe Report No. 2167

DTIC Science & Technology

1983-07-01

will soon be the case with the 104—can be produced equally well at all three establishments. As Jean Boillot, the head of Peugeot-Talbot, explains...the rise. "Yet another typically French evil," Jean Boillot observes. What are the reasons? Lumped together, agitation in the factories, general...suspect these measures of being efforts to regain ground lost. A Serious Handicap "In enthusiasm for work," as Citroen official Jacques Lombard

Novel methods for matter interferometry with nanosized objects

NASA Astrophysics Data System (ADS)

Arndt, Markus

2005-05-01

We discuss the current status and prospects for novel experimental methods for coherence^1,2 and decoherence^3 experiments with large molecules. Quantum interferometry with nanosized objects is interesting for the exploration of the quantum-classical transition. The same experimental setup is also promising for metrology applications and molecular nanolithography. Our coherence experiments with macromolecules employ a Talbot-Lau interferometer. We discuss some modifications to this scheme, which are required to extend it to particles with masses in excess of several thousand mass units. In particular, the detection in all previous interference experiments with large clusters and molecules, was based on either laser ionization^1 (e.g. Fullerenes) or electron impact ionization^2 (e.g. Porphyrins etc.). However, most ionization schemes run into efficiency limits when the mass and complexity of the target particle increases. Here we present experimental results for an interference detector which is truly scalable, i.e. one which will even improve with increasing particle size and complexity. ``Mechanically magnified fluorescence imaging'' (MMFI), combines the high spatial resolution, which is intrinsic to Talbot Lau interferometry with the high detection efficiency of fluorophores adsorbed onto a substrate. In the Talbot Lau setup a molecular interference pattern is revealed by scanning the 3^rd grating across the molecular beam^1. The number of transmitted molecules is a function of the relative position between the mask and the molecular density pattern. Both the particle interference pattern and the mechanical mask structure may be far smaller than any optical resolution limit. After mechanical magnification by an arbitrary factor, in our case a factor 5000, the interference pattern can still be inspected in fluorescence microscopy. The fluorescent molecules are collected on a surface which is scanned collinearly and synchronously behind the 3rd grating. The

Testing the role of metal hydrolysis in the anomalous electrodeposition of Ni-Fe alloys

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

Harris, T.M.; St. Clair, J.

1996-12-01

With the objective of testing several models of the anomalous codeposition (ACD) encountered in the electrodeposition of nickel-iron alloys, the effects of bath pH and complexing agents on the composition of deposits were examined. When the pH of the base line bath was increased from 3.0 to 5.0, the Ni/Fe mass ratio of the deposit increased (i.e., the deposition became less anomalous). The presence of tartrate ion in the bath produced a slight decrease in the Ni/Fe of the deposit. This complexing agent complexes ferric ion and thus prevents its precipitation but has little interaction with ferrous ion or nickelmore » ion under the electrodeposition conditions examined. The addition of ethylenediamine to the bath produced a significant increase in the Ni/Fe mass ratio. This complexing agent does not interact significantly with ferric ion or ferrous ion under the test conditions. None of these observations are consistent with the Dahms and Croll model of ACD. The effects of pH and tartaric acid on the deposit composition are consistent with the predictions of the Grande and Talbot model and the Matlosz model. The effect of ethylenediamine is not consistent with the Grande and Talbot model, but may be interpreted within the framework of the Matlosz model and the Hessami and Tobias model.« less

Approximation of the ruin probability using the scaled Laplace transform inversion

PubMed Central

Mnatsakanov, Robert M.; Sarkisian, Khachatur; Hakobyan, Artak

2015-01-01

The problem of recovering the ruin probability in the classical risk model based on the scaled Laplace transform inversion is studied. It is shown how to overcome the problem of evaluating the ruin probability at large values of an initial surplus process. Comparisons of proposed approximations with the ones based on the Laplace transform inversions using a fixed Talbot algorithm as well as on the ones using the Trefethen–Weideman–Schmelzer and maximum entropy methods are presented via a simulation study. PMID:26752796

A chat with Congress, from space on This Week @NASA – December 4, 2015

NASA Image and Video Library

2015-12-04

A Dec. 2 event with the House of Representatives Committee on Science, Space and Technology, featured a live chat with NASA’s Scott Kelly and Kjell Lindgren from onboard the International Space Station. Kelly and Lindgren answered questions from Texas Representative and Chairperson Lamar Smith and other committee members, about life on the station and the research on the orbital laboratory. Kelly is in the ninth month of his year-long mission with Russian cosmonaut Mikhail Kornienko to gather biomedical data that will help formulate a human mission to Mars, while Lindgren is preparing to return to Earth Dec. 11 to complete a 141-day mission. Also, Next space station crew preparing for launch, Orion powerhouse ready for testing, Anniversary of Orion’s first flight test, Your planet is changing. We’re on it, and Preparing Earth observation tool for space station!

Measurements of phoretic velocities of aerosol particles in microgravity conditions

NASA Astrophysics Data System (ADS)

Prodi, F.; Santachiara, G.; Travaini, S.; Vedernikov, A.; Dubois, F.; Minetti, C.; Legros, J. C.

2006-11-01

Measurements of thermo- and diffusio-phoretic velocities of aerosol particles (carnauba wax, paraffin and sodium chloride) were performed in microgravity conditions (Drop Tower facility, in Bremen, and Parabolic Flights, in Bordeaux). In the case of thermophoresis, a temperature gradient was obtained by heating the upper plate of the cell, while the lower one was maintained at environmental temperature. For diffusiophoresis, the water vapour gradient was obtained with sintered plates imbued with a water solution of MgCl 2 and distilled water, at the top and at the bottom of the cell, respectively. Aerosol particles were observed through a digital holographic velocimeter, a device allowing the determination of 3-D coordinates of particles from the observed volume. Particle trajectories and consequently particle velocities were reconstructed through the analysis of the sequence of particle positions. The experimental values of reduced thermophoretic velocities are between the theoretical values of Yamamoto and Ishihara [Yamamoto, K., Ishihara, Y., 1988. Thermophoresis of a spherical particle in a rarefied gas of a transition regime. Phys. Fluids. 31, 3618-3624] and Talbot et al. [Talbot, L., Cheng, R.K., Schefer, R.W., Willis, D.R., 1980. Thermophoresis of particles in a heated boundary layer. J. Fluid Mech. 101, 737-758], and do not show a clear dependence on the thermal conductivity of the aerosol. The existence of negative thermophoresis is not confirmed in our experiments. Concerning diffusiophoretic experiments, the results obtained show a small increase of reduced diffusiophoretic velocity with the Knudsen number.

Invited Article: Progress in coherent lithography using table-top extreme ultraviolet lasers

NASA Astrophysics Data System (ADS)

Li, W.; Urbanski, L.; Marconi, M. C.

2015-12-01

Compact (table top) lasers emitting at wavelengths below 50 nm had expanded the spectrum of applications in the extreme ultraviolet (EUV). Among them, the high-flux, highly coherent laser sources enabled lithographic approaches with distinctive characteristics. In this review, we will describe the implementation of a compact EUV lithography system capable of printing features with sub-50 nm resolution using Talbot imaging. This compact system is capable of producing consistent defect-free samples in a reliable and effective manner. Examples of different patterns and structures fabricated with this method will be presented.

Cygnus OA-4 Spacecraft on Approach to ISS

NASA Image and Video Library

2015-12-09

ISS045e176110 (12/09/2015) --- Using the International Space Station’s robotic arm, Canadarm2 (right) NASA Flight Engineer Kjell Lindgren prepares to capture Orbital ATK’s Cygnus cargo vehicle Dec. 09, 2015. The space station crew and the robotics officer in mission control in Houston will position Cygnus for installation to the orbiting laboratory’s Earth-facing port of the Unity module. Among the more than 7,000 pounds of supplies aboard Cygnus are numerous science and research investigations and technology demonstrations, including a new life science facility that will support studies on cell cultures, bacteria and other microorganisms; a microsatellite deployer and the first microsatellite that will be deployed from the space station; several other educational and technology demonstration CubeSats; and experiments that will study the behavior of gases and liquids, clarify the thermo-physical properties of molten steel, and evaluate flame-resistant textiles.

Born’s rule as signature of a superclassical current algebra

NASA Astrophysics Data System (ADS)

Fussy, S.; Mesa Pascasio, J.; Schwabl, H.; Grössing, G.

2014-04-01

We present a new tool for calculating the interference patterns and particle trajectories of a double-, three- and N-slit system on the basis of an emergent sub-quantum theory developed by our group throughout the last years. The quantum itself is considered as an emergent system representing an off-equilibrium steady state oscillation maintained by a constant throughput of energy provided by a classical zero-point energy field. We introduce the concept of a “relational causality” which allows for evaluating structural interdependences of different systems levels, i.e. in our case of the relations between partial and total probability density currents, respectively. Combined with the application of 21st century classical physics like, e.g., modern nonequilibrium thermodynamics, we thus arrive at a “superclassical” theory. Within this framework, the proposed current algebra directly leads to a new formulation of the guiding equation which is equivalent to the original one of the de Broglie-Bohm theory. By proving the absence of third order interferences in three-path systems it is shown that Born’s rule is a natural consequence of our theory. Considering the series of one-, double-, or, generally, of N-slit systems, with the first appearance of an interference term in the double slit case, we can explain the violation of Sorkin’s first order sum rule, just as the validity of all higher order sum rules. Moreover, the Talbot patterns and Talbot distance for an arbitrary N-slit device can be reproduced exactly by our model without any quantum physics tool.

Bone cartilage imaging with x-ray interferometry using a practical x-ray tube

NASA Astrophysics Data System (ADS)

Kido, Kazuhiro; Makifuchi, Chiho; Kiyohara, Junko; Itou, Tsukasa; Honda, Chika; Momose, Atsushi

2010-04-01

The purpose of this study was to design an X-ray Talbot-Lau interferometer for the imaging of bone cartilage using a practical X-ray tube and to develop that imaging system for clinical use. Wave-optics simulation was performed to design the interferometer with a practical X-ray tube, a source grating, two X-ray gratings, and an X-ray detector. An imaging system was created based on the results of the simulation. The specifications were as follows: the focal spot size was 0.3 mm of an X-ray tube with a tungsten anode (Toshiba, Tokyo, Japan). The tube voltage was set at 40 kVp with an additive aluminum filter, and the mean energy was 31 keV. The pixel size of the X-ray detector, a Condor 486 (Fairchild Imaging, California, USA), was 15 μm. The second grating was a Ronchi-type grating whose pitch was 5.3 μm. Imaging performance of the system was examined with X-ray doses of 0.5, 3 and 9 mGy so that the bone cartilage of a chicken wing was clearly depicted with X-ray doses of 3 and 9 mGy. This was consistent with the simulation's predictions. The results suggest that X-ray Talbot-Lau interferometry would be a promising tool in detecting soft tissues in the human body such as bone cartilage for the X-ray image diagnosis of rheumatoid arthritis. Further optimization of the system will follow to reduce the X-ray dose for clinical use.

Performance of Predictive Equations Specifically Developed to Estimate Resting Energy Expenditure in Ventilated Critically Ill Children.

PubMed

Jotterand Chaparro, Corinne; Taffé, Patrick; Moullet, Clémence; Laure Depeyre, Jocelyne; Longchamp, David; Perez, Marie-Hélène; Cotting, Jacques

2017-05-01

To determine, based on indirect calorimetry measurements, the biases of predictive equations specifically developed recently for estimating resting energy expenditure (REE) in ventilated critically ill children, or developed for healthy populations but used in critically ill children. A secondary analysis study was performed using our data on REE measured in a previous prospective study on protein and energy needs in pediatric intensive care unit. We included 75 ventilated critically ill children (median age, 21 months) in whom 407 indirect calorimetry measurements were performed. Fifteen predictive equations were used to estimate REE: the equations of White, Meyer, Mehta, Schofield, Henry, the World Health Organization, Fleisch, and Harris-Benedict and the tables of Talbot. Their differential and proportional biases (with 95% CIs) were computed and the bias plotted in graphs. The Bland-Altman method was also used. Most equations underestimated and overestimated REE between 200 and 1000 kcal/day. The equations of Mehta, Schofield, and Henry and the tables of Talbot had a bias ≤10%, but the 95% CI was large and contained values by far beyond ±10% for low REE values. Other specific equations for critically ill children had even wider biases. In ventilated critically ill children, none of the predictive equations tested met the performance criteria for the entire range of REE between 200 and 1000 kcal/day. Even the equations with the smallest bias may entail a risk of underfeeding or overfeeding, especially in the youngest children. Indirect calorimetry measurement must be preferred. Copyright © 2016 Elsevier Inc. All rights reserved.

Daniel Stern's journey in infant psychiatry: interview by John A. Talbot.

PubMed

Stern, Daniel

2012-12-01

This interview with Professor Daniel Stern, conducted on February 16, 2012 by Dr. John Talbott, reviews the field of infant psychiatry, the history of which goes back more than 100 years. Sigmund Freud, then Melanie Klein, Anna Freud, Donald Winnicott, and, finally, Margaret Mahler, all psychoanalysts, influenced its development. Direct observation of very young infants and their mothers began in the latter half of the 20th century, and the subsequent course shifted through the influence of developmental psychologists and ethologists. This review concludes with Dr. Stern's predictions and fears about future directions of the field.

Enabling laboratory EUV research with a compact exposure tool

NASA Astrophysics Data System (ADS)

Brose, Sascha; Danylyuk, Serhiy; Tempeler, Jenny; Kim, Hyun-su; Loosen, Peter; Juschkin, Larissa

2016-03-01

In this work we present the capabilities of the designed and realized extreme ultraviolet laboratory exposure tool (EUVLET) which has been developed at the RWTH-Aachen, Chair for the Technology of Optical Systems (TOS), in cooperation with the Fraunhofer Institute for Laser Technology (ILT) and Bruker ASC GmbH. Main purpose of this laboratory setup is the direct application in research facilities and companies with small batch production, where the fabrication of high resolution periodic arrays over large areas is required. The setup can also be utilized for resist characterization and evaluation of its pre- and post-exposure processing. The tool utilizes a partially coherent discharge produced plasma (DPP) source and minimizes the number of other critical components to a transmission grating, the photoresist coated wafer and the positioning system for wafer and grating and utilizes the Talbot lithography approach. To identify the limits of this approach first each component is analyzed and optimized separately and relations between these components are identified. The EUV source has been optimized to achieve the best values for spatial and temporal coherence. Phase-shifting and amplitude transmission gratings have been fabricated and exposed. Several commercially available electron beam resists and one EUV resist have been characterized by open frame exposures to determine their contrast under EUV radiation. Cold development procedure has been performed to further increase the resist contrast. By analyzing the exposure results it can be demonstrated that only a 1:1 copy of the mask structure can be fully resolved by the utilization of amplitude masks. The utilized phase-shift masks offer higher 1st order diffraction efficiency and allow a demagnification of the mask structure in the achromatic Talbot plane.

Puget Sound Tanker Size Optimization.

DTIC Science & Technology

1981-06-01

6.0 ENTIRE FLEET 190 175 1,428,657 12,779.0 609.0 .- 01w OIW 77’ a LJ Iz-I, 61- 0 0 d - J c- 6-8 CLJ 6-8 E- L9 - a LA~ 1VIOI 40 IN331f3d 78 As mentioned...Transportation, U.S. Coast Guard. Report no. CG- D -21-77. 25. Wardley-Smith, J ., ed. 1979. The prevention of oil pollution. 26. Goldberg, N.N., Keith, V.F...Coast Guard. 80. Kahn, D .; Talbot, T.; and Woodward, J . Jan. 1974. Vessel safety model: vol. III Programmers’ manual. Final report. For the U.S

Timing noise measurement of 320 GHz optical pulses using an improved optoelectronic harmonic mixer.

PubMed

Tsuchida, Hidemi

2006-03-01

An improved optoelectronic harmonic mixer (OEHM) has been employed for measuring the timing noise of 320 GHz optical pulses that are generated from a 160 GHz mode-locked laser diode by the temporal Talbot effect. The OEHM makes use of a low-drive voltage LiNbO3 modulator and a W-band unitraveling carrier photodiode for converting the 320 GHz pulse intensity into a low-frequency electrical signal. The time domain demodulation technique has been used for the precise evaluation of phase noise power spectral density. The rms timing jitter has been estimated to be 311 fs for the 10 Hz-18.6 MHz bandwidth.

A latitudinal study of oxygen isotopes within horsehair

NASA Astrophysics Data System (ADS)

Thompson, E.; Bronk Ramsey, C.; McConnell, J. R.

2016-12-01

This study aims to explore the hypothesis that 'if oxygen isotope ratios deplete with decreasing temperature then a study of oxygen isotope ratios within horsehair from Oxfordshire to Iceland will show a latitudinal depletion gradient'. By looking at oxygen isotope values at different geographical positions, we can track the relationship with latitude and with different regional climate features. This will provide a firmer understanding of how to compare climate records from different locations. Additionally, a comparison of the horse breeds from this study to those analysed within previous studies will create an even better understanding of the intra-species variation within the δ18O values of horsehair. A total of 24 horses were sampled on the 7th March from Thordale Stud in Shetland, the Icelandic Food And Veterinary Authority in Iceland, the Exmoor Pony Centre in Exmoor and the Pigeon House Equestrian Centre in Oxfordshire. By starting the sampling process from the most recent growth at the follicle, the sampling date becomes a chronological marker, temporally fixing the first sample within a sequential set of data points extending for one year or longer, depending on the length of each individual hair. The samples were analysed for oxygen isotope values using an IRMS coupled within a Sercon HTEA. Preliminary results show a latitudinal gradient is evident on comparison between the locations, consistent with the findings of Darling and Talbot's study of fresh water isotopes in the British Isles (2003). These results support the hypothesis, showing that a study of oxygen isotope ratios within horse hair from Oxfordshire to Iceland showing a latitudinal depletion gradient, consistent with a depletion of oxygen isotope ratios due to decreasing temperatures. Darling, W. and Talbot, J. (2003). The O and H stable isotope composition of freshwaters in the British Isles. 1. Rainfall. Hydrol. Earth System Science, 7(2), pp.163-181.

Hot and dense plasma probing by soft X-ray lasers

NASA Astrophysics Data System (ADS)

Krůs, M.; Kozlová, M.; Nejdl, J.; Rus, B.

2018-01-01

Soft X-ray lasers, due to their short wavelength, its brightness, and good spatial coherence, are excellent sources for the diagnostics of dense plasmas (up to 1025 cm-3) which are relevant to e.g. inertial fusion. Several techniques and experimental results, which are obtained at the quasi-steady state scheme being collisionally pumped 21.2 nm neon-like zinc laser installed at PALS Research Center, are presented here; among them the plasma density measurement by a double Lloyd mirror interferometer, deflectometer based on Talbot effect measuring plasma density gradients itself, with a following ray tracing postprocessing. Moreover, the high spatial resolution (nm scale) plasma images can be obtained when soft X-ray lasers are used.

Single-pulse interference caused by temporal reflection at moving refractive-index boundaries

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

Plansinis, Brent W.; Donaldson, William R.; Agrawal, Govind P.

Here, we show numerically and analytically that temporal reflections from a moving refractive-index boundary act as an analog of Lloyd’s mirror, allowing a single pulse to produce interference fringes in time as it propagates inside a dispersive medium. This interference can be viewed as the pulse interfering with a virtual pulse that is identical to the first, except for a π-phase shift. Furthermore, if a second moving refractive-index boundary is added to create the analog of an optical waveguide, a single pulse can be self-imaged or made to produce two or more pulses by adjusting the propagation length in amore » process similar to the Talbot effect.« less

Single-pulse interference caused by temporal reflection at moving refractive-index boundaries

DOE PAGES

Plansinis, Brent W.; Donaldson, William R.; Agrawal, Govind P.

2017-09-29

Here, we show numerically and analytically that temporal reflections from a moving refractive-index boundary act as an analog of Lloyd’s mirror, allowing a single pulse to produce interference fringes in time as it propagates inside a dispersive medium. This interference can be viewed as the pulse interfering with a virtual pulse that is identical to the first, except for a π-phase shift. Furthermore, if a second moving refractive-index boundary is added to create the analog of an optical waveguide, a single pulse can be self-imaged or made to produce two or more pulses by adjusting the propagation length in amore » process similar to the Talbot effect.« less

Dual light field and polarization imaging using CMOS diffractive image sensors.

PubMed

Jayasuriya, Suren; Sivaramakrishnan, Sriram; Chuang, Ellen; Guruaribam, Debashree; Wang, Albert; Molnar, Alyosha

2015-05-15

In this Letter we present, to the best of our knowledge, the first integrated CMOS image sensor that can simultaneously perform light field and polarization imaging without the use of external filters or additional optical elements. Previous work has shown how photodetectors with two stacks of integrated metal gratings above them (called angle sensitive pixels) diffract light in a Talbot pattern to capture four-dimensional light fields. We show, in addition to diffractive imaging, that these gratings polarize incoming light and characterize the response of these sensors to polarization and incidence angle. Finally, we show two applications of polarization imaging: imaging stress-induced birefringence and identifying specular reflections in scenes to improve light field algorithms for these scenes.

Optical computing and neural networks; Proceedings of the Meeting, National Chiao Tung Univ., Hsinchu, Taiwan, Dec. 16, 17, 1992

NASA Technical Reports Server (NTRS)

Hsu, Ken-Yuh (Editor); Liu, Hua-Kuang (Editor)

1992-01-01

The present conference discusses optical neural networks, photorefractive nonlinear optics, optical pattern recognition, digital and analog processors, and holography and its applications. Attention is given to bifurcating optical information processing, neural structures in digital halftoning, an exemplar-based optical neural net classifier for color pattern recognition, volume storage in photorefractive disks, and microlaser-based compact optical neuroprocessors. Also treated are the optical implementation of a feature-enhanced optical interpattern-associative neural network model and its optical implementation, an optical pattern binary dual-rail logic gate module, a theoretical analysis for holographic associative memories, joint transform correlators, image addition and subtraction via the Talbot effect, and optical wavelet-matched filters. (No individual items are abstracted in this volume)

Optical computing and neural networks; Proceedings of the Meeting, National Chiao Tung Univ., Hsinchu, Taiwan, Dec. 16, 17, 1992

NASA Astrophysics Data System (ADS)

Hsu, Ken-Yuh; Liu, Hua-Kuang

The present conference discusses optical neural networks, photorefractive nonlinear optics, optical pattern recognition, digital and analog processors, and holography and its applications. Attention is given to bifurcating optical information processing, neural structures in digital halftoning, an exemplar-based optical neural net classifier for color pattern recognition, volume storage in photorefractive disks, and microlaser-based compact optical neuroprocessors. Also treated are the optical implementation of a feature-enhanced optical interpattern-associative neural network model and its optical implementation, an optical pattern binary dual-rail logic gate module, a theoretical analysis for holographic associative memories, joint transform correlators, image addition and subtraction via the Talbot effect, and optical wavelet-matched filters. (No individual items are abstracted in this volume)

Geological survey of Maryland using EREP flight data. [mining, mapping, Chesapeake Bay islands, coastal water features

NASA Technical Reports Server (NTRS)

Weaver, K. N. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Underflight photography has been used in the Baltimore County mined land inventory to determine areas of disturbed land where surface mining of sand and ground clay, or stone has taken place. Both active and abandoned pits and quarries were located. Aircraft data has been used to update cultural features of Calvert, Caroline, St. Mary's, Somerset, Talbot, and Wicomico Counties. Islands have been located and catalogued for comparison with older film and map data for erosion data. Strip mined areas are being mapped to obtain total area disturbed to aid in future mining and reclamation problems. Coastal estuarine and Atlantic Coast features are being studied to determine nearshore bedforms, sedimentary, and erosional patterns, and manmade influence on natural systems.

Sub-Fourier characteristics of a δ-kicked-rotor resonance.

PubMed

Talukdar, I; Shrestha, R; Summy, G S

2010-07-30

We experimentally investigate the sub-Fourier behavior of a δ-kicked-rotor resonance by performing a measurement of the fidelity or overlap of a Bose-Einstein condensate exposed to a periodically pulsed standing wave. The temporal width of the fidelity resonance peak centered at the Talbot time and zero initial momentum exhibits an inverse cube pulse number (1/N3)-dependent scaling compared to a 1/N2 dependence for the mean energy width at the same resonance. A theoretical analysis shows that for an accelerating potential the width of the resonance in acceleration space depends on 1/N3, a property which we also verify experimentally. Such a sub-Fourier effect could be useful for high precision gravity measurements.

Energy weighted x-ray dark-field imaging.

PubMed

Pelzer, Georg; Zang, Andrea; Anton, Gisela; Bayer, Florian; Horn, Florian; Kraus, Manuel; Rieger, Jens; Ritter, Andre; Wandner, Johannes; Weber, Thomas; Fauler, Alex; Fiederle, Michael; Wong, Winnie S; Campbell, Michael; Meiser, Jan; Meyer, Pascal; Mohr, Jürgen; Michel, Thilo

2014-10-06

The dark-field image obtained in grating-based x-ray phase-contrast imaging can provide information about the objects' microstructures on a scale smaller than the pixel size even with low geometric magnification. In this publication we demonstrate that the dark-field image quality can be enhanced with an energy-resolving pixel detector. Energy-resolved x-ray dark-field images were acquired with a 16-energy-channel photon-counting pixel detector with a 1 mm thick CdTe sensor in a Talbot-Lau x-ray interferometer. A method for contrast-noise-ratio (CNR) enhancement is proposed and validated experimentally. In measurements, a CNR improvement by a factor of 1.14 was obtained. This is equivalent to a possible radiation dose reduction of 23%.

Near-field interferometry of a free-falling nanoparticle from a point-like source

NASA Astrophysics Data System (ADS)

Bateman, James; Nimmrichter, Stefan; Hornberger, Klaus; Ulbricht, Hendrik

2014-09-01

Matter-wave interferometry performed with massive objects elucidates their wave nature and thus tests the quantum superposition principle at large scales. Whereas standard quantum theory places no limit on particle size, alternative, yet untested theories—conceived to explain the apparent quantum to classical transition—forbid macroscopic superpositions. Here we propose an interferometer with a levitated, optically cooled and then free-falling silicon nanoparticle in the mass range of one million atomic mass units, delocalized over >150 nm. The scheme employs the near-field Talbot effect with a single standing-wave laser pulse as a phase grating. Our analysis, which accounts for all relevant sources of decoherence, indicates that this is a viable route towards macroscopic high-mass superpositions using available technology.

To Rabi Hamiltonian through their Time Dependent Terms can be Reckons as Fractals

NASA Astrophysics Data System (ADS)

Rosary-Oyong, Se, Glory

2016-03-01

For light-matters interactions, ever replies by theLate HE. Mr. Prof M. Barmawi through Bose-Einstein condensates matter-waves ever retrieves [Boyce & DiPrima, 2015] instead of Richard Courant cq HE. Mr. Prof. Sudjoko Danusubroto's LKTM, Lustrum VI ITB, March 2, 1984. Follows ``Modified kernel to Quantum systems thorough Laplace inverse transformation'' whereas ``karyon'' in prokaryotes/eukaryotes meant as well as `kernel' , have been sought for `growth curve' & `potential of proton to other protons' the time dependent terms cos (ωt)exp[-iωot] whose integration y = sin ωt + c proves to be fractals h. 3 guided by Rabi Hamiltonian from Isidor Isaac Rabi,1944. Accompanying ``the Theory of Scale Relativity'' from Laurent Nottale/LUTH, the proofs of considerances whereas `time also are fractals', from Norways for Infra OMAN soughts a benchmark portfolio from Kjell Storvik, 2004: ``Socially Responsible Investment Strategies for the Norwegian Petroleum Fund'' whereas the Rabi frequency ? = 2 ɛ.deg/h can be relatively in comparisons expressed of capacitive [E.d/h]. Acknowledgment to HE. Mr. AUGUST PARENGKUAN if accepts 1995-2005 Invoicing & Fulfillments to ``KOMPAS'' cq the Prodi of Physics ITB.

SPEAR (Space Plasma Exploration by Active Radar): New Developments and Future Plans

NASA Astrophysics Data System (ADS)

Baddeley, L. J.; Oksavik, K.

2009-12-01

The SPEAR heating facility is located on Svalbard at 75° CGM latitude and as such is 10° closer to a geomagnetic pole than any current ionospheric heating facility. It thus has the unique ability to perform heating experiments inside the polar cap at all local times. It is co-located with several facilities, including the EISCAT Svalbard Radar, the SOUZY radar and the Kjell Henriksen Observatory. After much speculation regarding the operational future of the SPEAR facility, UNIS has taken ownership of the system, with a 3 year research and operational grant from the Norwegian Research Council. The facility has a detailed and successful research history, with results having already been presented at international scientific conferences and appeared in 13 peer-review papers in international journals. Successful experiments have been carried out using both X and O mode polarisation in conjunction with both ground and space based instrumentation. Additionally, the operational frequency the facility (4.45 - 5.825 MHz) means that its scientific capabilities will increase towards the next solar activity maximum in 2012. Future plans, both experimentally and logistically will be discussed in additional to possibilities for future experimental collaborations

Miniaturized optical wavelength sensors

NASA Astrophysics Data System (ADS)

Kung, Helen Ling-Ning

Recently semiconductor processing technology has been applied to the miniaturization of optical wavelength sensors. Compact sensors enable new applications such as integrated diode-laser wavelength monitors and frequency lockers, portable chemical and biological detection, and portable and adaptive hyperspectral imaging arrays. Small sensing systems have trade-offs between resolution, operating range, throughput, multiplexing and complexity. We have developed a new wavelength sensing architecture that balances these parameters for applications involving hyperspectral imaging spectrometer arrays. In this thesis we discuss and demonstrate two new wavelength-sensing architectures whose single-pixel designs can easily be extended into spectrometer arrays. The first class of devices is based on sampling a standing wave. These devices are based on measuring the wavelength-dependent period of optical standing waves formed by the interference of forward and reflected waves at a mirror. We fabricated two different devices based on this principle. The first device is a wavelength monitor, which measures the wavelength and power of a monochromatic source. The second device is a spectrometer that can also act as a selective spectral coherence sensor. The spectrometer contains a large displacement piston-motion MEMS mirror and a thin GaAs photodiode flip-chip bonded to a quartz substrate. The performance of this spectrometer is similar to that of a Michelson in resolution, operating range, throughput and multiplexing but with the added advantages of fewer components and one-dimensional architecture. The second class of devices is based on the Talbot self-imaging effect. The Talbot effect occurs when a periodic object is illuminated with a spatially coherent wave. Periodically spaced self-images are formed behind the object. The spacing of the self-images is proportional to wavelength of the incident light. We discuss and demonstrate how this effect can be used for spectroscopy

Cetylpyridinium chloride/magnetic alginate beads: an efficient system to remove p-nitrophenol from wastewater

NASA Astrophysics Data System (ADS)

Obeid, Layaly; Bee, Agnes; Talbot, Delphine; Abramson, Sebastien; Welschbillig, Mathias

2014-05-01

The adsorption process is one of the most efficient methods to remove pollutants from wastewater provided that suitable adsorbents are used. In order to produce environmentally safe adsorbents, natural polymers have received increasing attention in recent years. Thus, alginate, a polysaccharide extracted from brown seaweeds, is extensively used as inexpensive, non-toxic and efficient biosorbent. Furthermore, it has been shown that the encapsulation of magnetic materials in alginate beads facilitates their recovery from wastewater after the adsorption step, by the use of an external magnetic field gradient, obtained with a magnet or an electromagnet [1, 2]. In the present work, we have studied the adsorption affinity of magnetic alginate beads (called magsorbents)for p-nitrophenol (PNP), used as a hydrophobic pollutant, in presence of cetylpyridinium chloride (CPC), a cationic surfactant. First, the effect of different parameters (pH solution, contact time, surfactant initial concentration…) on the adsorption of CPC on the alginate beads was investigated. Adsorption of the surfactant occurs due to electrostatic attractions between its cationic head groups and negative carboxylate functions of the alginate beads. At larger surfactant concentrations, adsorption is also due to the interaction between the hydrocarbon chains of CPC forming aggregated structures capable of solubilizing hydrophobic solutes. In a second step, we showed that PNP can reach up to 95% of adsorption in the beads in presence of CPC, although the pollutant is poorly adsorbed by alginate in absence of the surfactant. At highest CPC concentrations, desorption occurs as micellar solubilization is preferred over coadsorption. Our magsorbents appear to efficiently remove both cationic surfactant and hydrophobic pollutants and we hope that this fundamental research will be helpful for the future development of magnetically assisted processes in water treatment plants. 1. A.Bee, D.Talbot, S.Abramson, V

3D-fabrication of tunable and high-density arrays of crystalline silicon nanostructures

NASA Astrophysics Data System (ADS)

Wilbers, J. G. E.; Berenschot, J. W.; Tiggelaar, R. M.; Dogan, T.; Sugimura, K.; van der Wiel, W. G.; Gardeniers, J. G. E.; Tas, N. R.

2018-04-01

In this report, a procedure for the 3D-nanofabrication of ordered, high-density arrays of crystalline silicon nanostructures is described. Two nanolithography methods were utilized for the fabrication of the nanostructure array, viz. displacement Talbot lithography (DTL) and edge lithography (EL). DTL is employed to perform two (orthogonal) resist-patterning steps to pattern a thin Si3N4 layer. The resulting patterned double layer serves as an etch mask for all further etching steps for the fabrication of ordered arrays of silicon nanostructures. The arrays are made by means of anisotropic wet etching of silicon in combination with an isotropic retraction etch step of the etch mask, i.e. EL. The procedure enables fabrication of nanostructures with dimensions below 15 nm and a potential density of 1010 crystals cm-2.

Habitat Suitability Index Models and Instream Flow Suitability Curves: American shad

USGS Publications Warehouse

Stier, David J.; Crance, Johnie H.

1985-01-01

INTRODUCTION The American shad, an anadromous species, is the largest member of the herring family (Clupeidae) and is native to North America (Talbot and Sykes 1958; Hildebrand 1963; Walburg and Nichols 1967). Historically, the commercial fishery for American shad on the Atlantic coast was widespread and intense; in 1896 the estimated catch was 22.7 million kg (50 million lb). By 1960, however, the estimated catch had dropped to slightly more than 3.6 million kg (8 million lb), according to Walburg and Nichols (1967). Pollution, overfishing, and dams constructed across streams that prevent shad from reaching their spawning grounds have caused partial or total depletion of stocks (Hildebrand 1963). Several programs aimed at restoring American shad to their former range have been initiated by Federal and State agencies.

Pope and Talbot, Inc., Petition for Objection to Issuance of Title V Operating Permit

EPA Pesticide Factsheets

This document may be of assistance in applying the Title V air operating permit regulations. This document is part of the Title V Petition Database available at www2.epa.gov/title-v-operating-permits/title-v-petition-database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

Analysis of reflection-peak wavelengths of sampled fiber Bragg gratings with large chirp.

PubMed

Zou, Xihua; Pan, Wei; Luo, Bin

2008-09-10

The reflection-peak wavelengths (RPWs) in the spectra of sampled fiber Bragg gratings with large chirp (SFBGs-LC) are theoretically investigated. Such RPWs are divided into two parts, the RPWs of equivalent uniform SFBGs (U-SFBGs) and the wavelength shift caused by the large chirp in the grating period (CGP). We propose a quasi-equivalent transform to deal with the CGP. That is, the CGP is transferred into quasi-equivalent phase shifts to directly derive the Fourier transform of the refractive index modulation. Then, in the case of both the direct and the inverse Talbot effect, the wavelength shift is obtained from the Fourier transform. Finally, the RPWs of SFBGs-LC can be achieved by combining the wavelength shift and the RPWs of equivalent U-SFBGs. Several simulations are shown to numerically confirm these predicted RPWs of SFBGs-LC.

Geologic isolation of nuclear waste at high latitudes: the role of ice sheets

USGS Publications Warehouse

Person, M.; McIntosh, J.; Iverson, N.; Neuzil, C.E.; Bense, V.

2012-01-01

Geologic isolation of high-level nuclear waste from the biosphere requires special consideration in countries at high latitudes (>40°N) owing to the possibility of future episodes of continental glaciation (Talbot 1999). It is now widely recognized that Pleistocene continental glaciations have had a profound effect on rates of sediment erosion (Cuffey & Paterson 2010) and deformation including tectonic thrusting (Pedersen 2005) as well as groundwater flow (Person et al. 2007; Lemieux et al. 2008a,b,c). In addition, glacial mechanical loads may have generated anomalous, or fossil, pore pressures within certain clay-rich confining units (e.g. Vinard et al. 2001). Because high-level nuclear wastes must be isolated from the biosphere as long as 1 million years (McMurry et al. 2003), the likelihood of one or more continental ice sheets overrunning high-latitude sites must be considered.

Isotropic scalar image visualization of vector differential image data using the inverse Riesz transform.

PubMed

Larkin, Kieran G; Fletcher, Peter A

2014-03-01

X-ray Talbot moiré interferometers can now simultaneously generate two differential phase images of a specimen. The conventional approach to integrating differential phase is unstable and often leads to images with loss of visible detail. We propose a new reconstruction method based on the inverse Riesz transform. The Riesz approach is stable and the final image retains visibility of high resolution detail without directional bias. The outline Riesz theory is developed and an experimentally acquired X-ray differential phase data set is presented for qualitative visual appraisal. The inverse Riesz phase image is compared with two alternatives: the integrated (quantitative) phase and the modulus of the gradient of the phase. The inverse Riesz transform has the computational advantages of a unitary linear operator, and is implemented directly as a complex multiplication in the Fourier domain also known as the spiral phase transform.

Grating-based x-ray differential phase contrast imaging with twin peaks in phase-stepping curves—phase retrieval and dewrapping

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

Yang, Yi; Xie, Huiqiao; Tang, Xiangyang, E-mail: xiangyang.tang@emory.edu

Purpose: X-ray differential phase contrast CT implemented with Talbot interferometry employs phase-stepping to extract information of x-ray attenuation, phase shift, and small-angle scattering. Since inaccuracy may exist in the absorption grating G{sub 2} due to an imperfect fabrication, the effective period of G{sub 2} can be as large as twice the nominal period, leading to a phenomenon of twin peaks that differ remarkably in their heights. In this work, the authors investigate how to retrieve and dewrap the phase signal from the phase-stepping curve (PSC) with the feature of twin peaks for x-ray phase contrast imaging. Methods: Based on themore » paraxial Fresnel–Kirchhoff theory, the analytical formulae to characterize the phenomenon of twin peaks in the PSC are derived. Then an approach to dewrap the retrieved phase signal by jointly using the phases of the first- and second-order Fourier components is proposed. Through an experimental investigation using a prototype x-ray phase contrast imaging system implemented with Talbot interferometry, the authors evaluate and verify the derived analytic formulae and the proposed approach for phase retrieval and dewrapping. Results: According to theoretical analysis, the twin-peak phenomenon in PSC is a consequence of combined effects, including the inaccuracy in absorption grating G{sub 2}, mismatch between phase grating and x-ray source spectrum, and finite size of x-ray tube’s focal spot. The proposed approach is experimentally evaluated by scanning a phantom consisting of organic materials and a lab mouse. The preliminary data show that compared to scanning G{sub 2} over only one single nominal period and correcting the measured phase signal with an intuitive phase dewrapping method that is being used in the field, stepping G{sub 2} over twice its nominal period and dewrapping the measured phase signal with the proposed approach can significantly improve the quality of x-ray differential phase contrast imaging

ADHydro: A Large-scale High Resolution Multi-Physics Distributed Water Resources Model for Water Resource Simulations in a Parallel Computing Environment

NASA Astrophysics Data System (ADS)

lai, W.; Steinke, R. C.; Ogden, F. L.

2013-12-01

Physics-based watershed models are useful tools for hydrologic studies, water resources management and economic analyses in the contexts of climate, land-use, and water-use changes. This poster presents development of a physics-based, high-resolution, distributed water resources model suitable for simulating large watersheds in a massively parallel computing environment. Developing this model is one of the objectives of the NSF EPSCoR RII Track II CI-WATER project, which is joint between Wyoming and Utah. The model, which we call ADHydro, is aimed at simulating important processes in the Rocky Mountain west, includes: rainfall and infiltration, snowfall and snowmelt in complex terrain, vegetation and evapotranspiration, soil heat flux and freezing, overland flow, channel flow, groundwater flow and water management. The ADHydro model uses the explicit finite volume method to solve PDEs for 2D overland flow, 2D saturated groundwater flow coupled to 1D channel flow. The model has a quasi-3D formulation that couples 2D overland flow and 2D saturated groundwater flow using the 1D Talbot-Ogden finite water-content infiltration and redistribution model. This eliminates difficulties in solving the highly nonlinear 3D Richards equation, while the finite volume Talbot-Ogden infiltration solution is computationally efficient, guaranteed to conserve mass, and allows simulation of the effect of near-surface groundwater tables on runoff generation. The process-level components of the model are being individually tested and validated. The model as a whole will be tested on the Green River basin in Wyoming and ultimately applied to the entire Upper Colorado River basin. ADHydro development has necessitated development of tools for large-scale watershed modeling, including open-source workflow steps to extract hydromorphological information from GIS data, integrate hydrometeorological and water management forcing input, and post-processing and visualization of large output data

Optical fabrication and testing; Proceedings of the Meeting, Singapore, Oct. 22-27, 1990

NASA Astrophysics Data System (ADS)

Lorenzen, Manfred; Campbell, Duncan R.; Johnson, Craig W.

1991-03-01

Various papers on optical fabrication and testing are presented. Individual topics addressed include: interferometry with laser diodes, new methods for economic production of prisms and lenses, interferometer accuracy and precision, optical testing with wavelength scanning interferometer, digital Talbot interferometer, high-sensitivity interferometric technique for strain measurements, absolute interferometric testing of spherical surfaces, contouring using gratings created on an LCD panel, three-dimensional inspection using laser-based dynamic fringe projection, noncontact optical microtopography, laser scan microscope and infrared laser scan microscope, photon scanning tunneling microscopy. Also discussed are: combination-matching problems in the layout design of minilaser rangefinder, design and testing of a cube-corner array for laser ranging, mode and far-field pattern of diode laser-phased arrays, new glasses for optics and optoelectronics, optical properties of Li-doped ZnO films, application and machining of Zerodur for optical purposes, finish machining of optical components in mass production.

Enhancing Tabletop X-Ray Phase Contrast Imaging with Nano-Fabrication

PubMed Central

Miao, Houxun; Gomella, Andrew A.; Harmon, Katherine J.; Bennett, Eric E.; Chedid, Nicholas; Znati, Sami; Panna, Alireza; Foster, Barbara A.; Bhandarkar, Priya; Wen, Han

2015-01-01

X-ray phase-contrast imaging is a promising approach for improving soft-tissue contrast and lowering radiation dose in biomedical applications. While current tabletop imaging systems adapt to common x-ray tubes and large-area detectors by employing absorptive elements such as absorption gratings or monolithic crystals to filter the beam, we developed nanometric phase gratings which enable tabletop x-ray far-field interferometry with only phase-shifting elements, leading to a substantial enhancement in the performance of phase contrast imaging. In a general sense the method transfers the demands on the spatial coherence of the x-ray source and the detector resolution to the feature size of x-ray phase masks. We demonstrate its capabilities in hard x-ray imaging experiments at a fraction of clinical dose levels and present comparisons with the existing Talbot-Lau interferometer and with conventional digital radiography. PMID:26315891

X-ray phase-contrast imaging at 100 keV on a conventional source

PubMed Central

Thüring, T.; Abis, M.; Wang, Z.; David, C.; Stampanoni, M.

2014-01-01

X-ray grating interferometry is a promising imaging technique sensitive to attenuation, refraction and scattering of the radiation. Applications of this technique in the energy range between 80 and 150 keV pose severe technical challenges, and are still mostly unexplored. Phase-contrast X-ray imaging at such high energies is of relevant scientific and industrial interest, in particular for the investigation of strongly absorbing or thick materials as well as for medical imaging. Here we show the successful implementation of a Talbot-Lau interferometer operated at 100 keV using a conventional X-ray tube and a compact geometry, with a total length of 54 cm. We present the edge-on illumination of the gratings in order to overcome the current fabrication limits. Finally, the curved structures match the beam divergence and allow a large field of view on a short and efficient setup. PMID:24903579

X-ray simulations method for the large field of view

NASA Astrophysics Data System (ADS)

Schelokov, I. A.; Grigoriev, M. V.; Chukalina, M. V.; Asadchikov, V. E.

2018-03-01

In the standard approach, X-ray simulation is usually limited to the step of spatial sampling to calculate the convolution of integrals of the Fresnel type. Explicitly the sampling step is determined by the size of the last Fresnel zone in the beam aperture. In other words, the spatial sampling is determined by the precision of integral convolution calculations and is not connected with the space resolution of an optical scheme. In the developed approach the convolution in the normal space is replaced by computations of the shear strain of ambiguity function in the phase space. The spatial sampling is then determined by the space resolution of an optical scheme. The sampling step can differ in various directions because of the source anisotropy. The approach was used to simulate original images in the X-ray Talbot interferometry and showed that the simulation can be applied to optimize the methods of postprocessing.

Inscription of first order fiber Bragg gratings in sapphire fibers by 400 nm femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Elsmann, Tino; Habisreuther, Tobias; Graf, Albrecht; Rothhardt, Manfred; Bartelt, Hartmut

2013-05-01

We demonstrate the inscription of fiber Bragg gratings in single crystalline sapphire using the second harmonic of a Ti:Sa-amplified femtosecond laser system. With the laser wavelength of 400 nm first order gratings were fabricated. The interferometric inscription was performed out using the Talbot interferometer. This way, not only single gratings but also multiplexed sensor arrays were realized. For evaluating of the sensor signals an adapted multimodal interrogation setup was build up, because the sapphire fiber is an extreme multimodal air clad fiber. Due to the multimodal reflection spectrum, different peak functions have been tested to evaluate the thermal properties of the grating. The temperature sensors were tested for high temperature applications up to 1200°C with a thermal sensitivity in the order of 25 pm/K which is more than the doubled of that one reached with Bragg gratings in conventional silica fibers.

Isotropic scalar image visualization of vector differential image data using the inverse Riesz transform

PubMed Central

Larkin, Kieran G.; Fletcher, Peter A.

2014-01-01

X-ray Talbot moiré interferometers can now simultaneously generate two differential phase images of a specimen. The conventional approach to integrating differential phase is unstable and often leads to images with loss of visible detail. We propose a new reconstruction method based on the inverse Riesz transform. The Riesz approach is stable and the final image retains visibility of high resolution detail without directional bias. The outline Riesz theory is developed and an experimentally acquired X-ray differential phase data set is presented for qualitative visual appraisal. The inverse Riesz phase image is compared with two alternatives: the integrated (quantitative) phase and the modulus of the gradient of the phase. The inverse Riesz transform has the computational advantages of a unitary linear operator, and is implemented directly as a complex multiplication in the Fourier domain also known as the spiral phase transform. PMID:24688823

Effect of Nanohole Spacing on the Self-Imaging Phenomenon Created by the Three-Dimensional Propagation of Light through Periodic Nanohole Arrays

PubMed Central

Chowdhury, Mustafa H.; Lindquist, Nathan C.; Lesuffleur, Antoine; Oh, Sang-Hyun; Lakowicz, Joseph R.; Ray, Krishanu

2013-01-01

We present a detailed study of the inter-nanohole distance that governs the self-imaging phenomenon created by the three-dimensional propagation of light through periodic nanohole arrays on plasmonic substrates. We used scanning near-field optical microscopy (SNOM) to map the light intensity distributions at various heights above 10×10 nanohole arrays of varying pitch sizes on silver films. Our results suggest the inter-hole spacing has to be greater than the wavelength of the incident light to create the self-imaging phenomenon. We also present Finite-Difference Time-Domain (FDTD) calculations which show qualitative corroboration of our experimental results. Both our experimental and FDTD results show that the self-imaging phenomenon is more pronounced for structures with larger pitch sizes. We believe this self-imaging phenomenon is related to the Talbot imaging effect that has also been modified by a plasmonic component and can potentially be used to provide the basis for a new class of optical microscopes. PMID:24416456

Precise and fast spatial-frequency analysis using the iterative local Fourier transform.

PubMed

Lee, Sukmock; Choi, Heejoo; Kim, Dae Wook

2016-09-19

The use of the discrete Fourier transform has decreased since the introduction of the fast Fourier transform (fFT), which is a numerically efficient computing process. This paper presents the iterative local Fourier transform (ilFT), a set of new processing algorithms that iteratively apply the discrete Fourier transform within a local and optimal frequency domain. The new technique achieves 2¹⁰ times higher frequency resolution than the fFT within a comparable computation time. The method's superb computing efficiency, high resolution, spectrum zoom-in capability, and overall performance are evaluated and compared to other advanced high-resolution Fourier transform techniques, such as the fFT combined with several fitting methods. The effectiveness of the ilFT is demonstrated through the data analysis of a set of Talbot self-images (1280 × 1024 pixels) obtained with an experimental setup using grating in a diverging beam produced by a coherent point source.

Visual optics: an engineering approach

NASA Astrophysics Data System (ADS)

Toadere, Florin

2010-11-01

The human eyes' visual system interprets the information from the visible light in order to build a representation of the world surrounding the body. It derives color by comparing the responses to light from the three types of photoreceptor cones in the eyes. These long medium and short cones are sensitive to blue, green and red portions of the visible spectrum. We simulate the color vision for the normal eyes. We see the effects of the dyes, filters, glasses and windows on color perception when the test image is illuminated with the D65 light sources. In addition to colors' perception, the human eyes can suffer from diseases and disorders. The eye can be seen as an optical instrument which has its own eye print. We present aspects of some nowadays methods and technologies which can capture and correct the human eyes' wavefront aberrations. We focus our attention to Siedel aberrations formula, Zenike polynomials, Shack-Hartmann Sensor, LASIK, interferograms fringes aberrations and Talbot effect.

Optical fabrication and testing; Proceedings of the Meeting, Singapore, Oct. 22-27, 1990

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

Lorenzen, M.; Campbell, D.R.; Johnson, C.W.

1991-01-01

Various papers on optical fabrication and testing are presented. Individual topics addressed include: interferometry with laser diodes, new methods for economic production of prisms and lenses, interferometer accuracy and precision, optical testing with wavelength scanning interferometer, digital Talbot interferometer, high-sensitivity interferometric technique for strain measurements, absolute interferometric testing of spherical surfaces, contouring using gratings created on an LCD panel, three-dimensional inspection using laser-based dynamic fringe projection, noncontact optical microtopography, laser scan microscope and infrared laser scan microscope, photon scanning tunneling microscopy. Also discussed are: combination-matching problems in the layout design of minilaser rangefinder, design and testing of a cube-corner arraymore » for laser ranging, mode and far-field pattern of diode laser-phased arrays, new glasses for optics and optoelectronics, optical properties of Li-doped ZnO films, application and machining of Zerodur for optical purposes, finish machining of optical components in mass production.« less

Correction of data truncation artifacts in differential phase contrast (DPC) tomosynthesis imaging

NASA Astrophysics Data System (ADS)

Garrett, John; Ge, Yongshuai; Li, Ke; Chen, Guang-Hong

2015-10-01

The use of grating based Talbot-Lau interferometry permits the acquisition of differential phase contrast (DPC) imaging with a conventional medical x-ray source and detector. However, due to the limited area of the gratings, limited area of the detector, or both, data truncation image artifacts are often observed in tomographic DPC acquisitions and reconstructions, such as tomosynthesis (limited-angle tomography). When data are truncated in the conventional x-ray absorption tomosynthesis imaging, a variety of methods have been developed to mitigate the truncation artifacts. However, the same strategies used to mitigate absorption truncation artifacts do not yield satisfactory reconstruction results in DPC tomosynthesis reconstruction. In this work, several new methods have been proposed to mitigate data truncation artifacts in a DPC tomosynthesis system. The proposed methods have been validated using experimental data of a mammography accreditation phantom, a bovine udder, as well as several human cadaver breast specimens using a bench-top DPC imaging system at our facility.

Multinomial modeling and an evaluation of common data-mining algorithms for identifying signals of disproportionate reporting in pharmacovigilance databases.

PubMed

Johnson, Kjell; Guo, Cen; Gosink, Mark; Wang, Vicky; Hauben, Manfred

2012-12-01

A principal objective of pharmacovigilance is to detect adverse drug reactions that are unknown or novel in terms of their clinical severity or frequency. One method is through inspection of spontaneous reporting system databases, which consist of millions of reports of patients experiencing adverse effects while taking one or more drugs. For such large databases, there is an increasing need for quantitative and automated screening tools to assist drug safety professionals in identifying drug-event combinations (DECs) worthy of further investigation. Existing algorithms can effectively identify problematic DECs when the frequencies are high. However these algorithms perform differently for low-frequency DECs. In this work, we provide a method based on the multinomial distribution that identifies signals of disproportionate reporting, especially for low-frequency combinations. In addition, we comprehensively compare the performance of commonly used algorithms with the new approach. Simulation results demonstrate the advantages of the proposed method, and analysis of the Adverse Event Reporting System data shows that the proposed method can help detect interesting signals. Furthermore, we suggest that these methods be used to identify DECs that occur significantly less frequently than expected, thus identifying potential alternative indications for these drugs. We provide an empirical example that demonstrates the importance of exploring underexpected DECs. Code to implement the proposed method is available in R on request from the corresponding authors. kjell@arboranalytics.com or Mark.M.Gosink@Pfizer.com Supplementary data are available at Bioinformatics online.

Far-field interference of a neutron white beam and the applications to noninvasive phase-contrast imaging

NASA Astrophysics Data System (ADS)

Pushin, D. A.; Sarenac, D.; Hussey, D. S.; Miao, H.; Arif, M.; Cory, D. G.; Huber, M. G.; Jacobson, D. L.; LaManna, J. M.; Parker, J. D.; Shinohara, T.; Ueno, W.; Wen, H.

2017-04-01

The phenomenon of interference plays a crucial role in the field of precision measurement science. Wave-particle duality has expanded the well-known interference effects of electromagnetic waves to massive particles. The majority of the wave-particle interference experiments require a near monochromatic beam which limits its applications due to the resulting low intensity. Here we demonstrate white beam interference in the far-field regime using a two-phase-grating neutron interferometer and its application to phase-contrast imaging. The functionality of this interferometer is based on the universal moiré effect that allows us to improve upon the standard Lau setup. Interference fringes were observed with monochromatic and polychromatic neutron beams for both continuous and pulsed beams. Far-field neutron interferometry allows for the full utilization of intense neutron sources for precision measurements of gradient fields. It also overcomes the alignment, stability, and fabrication challenges associated with the more familiar perfect-crystal neutron interferometer, as well as avoids the loss of intensity due to the absorption analyzer grating requirement in Talbot-Lau interferometer.

Numerical modeling of gravel bed river response to meander straightening: The coupling between the evolution of bed pavement and long profile

NASA Astrophysics Data System (ADS)

Talbot, Tracey; Lapointe, Michel

2002-06-01

Artificial meander straightening (rectification) was conducted in the early 1960s along the Sainte-Marguerite River, Canada, in order to facilitate highway construction along the valley. Previous studies [Talbot and Lapointe, 2002] confirm that vertical reprofiling, coupled with pavement coarsening in the degrading reach, were the main responses counteracting the disequilibrium in gravel transport rates triggered at rectification of this system. Numerical simulations, using SEDROUT2.0, a one-dimensional hydraulic and sediment transport model, and validated against the observed channel response, show the important role played by an advancing wave of pavement coarsening down the rectified reach in modulating the bed degradation response. Simulations extending into the future reveal an asymptotically slowing approach to equilibrium in the middle of the 21st century, with a response half-time of the order of 10 years. In near-threshold gravel bed systems like the Sainte-Marguerite River, pavement coarsening after rectification buffers the system against extreme degradation. Most significantly for watershed management, this also appears to severely limit the extent of propagation of degradation upstream of the rectification.

Peptides and proteins in matter wave interferometry: Challenges and prospects

NASA Astrophysics Data System (ADS)

Sezer, Ugur; Geyer, Philipp; Mairhofer, Lukas; Brand, Christian; Doerre, Nadine; Rodewald, Jonas; Schaetti, Jonas; Koehler, Valentin; Mayor, Marcel; Arndt, Markus

2016-05-01

Recent developments in matter wave physics suggest that quantum interferometry with biologically relevant nanomaterials is becoming feasible for amino acids, peptides, proteins and RNA/DNA strands. Quantum interference of biomolecules is interesting as it can mimic Schrödinger's cat states with molecules of high mass, elevated temperature and biological functionality. Additionally, the high internal complexity can give rise to a rich variety of couplings to the environment and new handles for quantitative tests of quantum decoherence. Finally, matter wave interferometers are highly sensitive force sensors and pave the way for quantum-assisted measurements of biomolecular properties in interaction with tailored or biomimetic environments. Recent interferometer concepts such as the Kapitza-Dirac-Talbot-Lau interferometer (KDTLI) or the Optical Time-domain Matter Wave interferometer (OTIMA) have already proven their potential for quantum optics in the mass range beyond 10000 amu and for metrology. Here we show our advances in quantum interferometry with vitamins and peptides and discuss methods of realizing cold, intense and sufficiently slow beams of synthetically tailored or hydrated polypeptides with promising properties for a new generation of quantum optics.

Electron density and effective atomic number (Zeff) determination through x-ray Moiré deflectometry

NASA Astrophysics Data System (ADS)

Valdivia Leiva, Maria Pia; Stutman, Dan; Finkenthal, Michael

2014-10-01

Talbot-Lau based Moiré deflectometry is a powerful density diagnostic capable of delivering refraction information and attenuation from a single image, through the accurate detection of X-ray phase-shift and intensity. The technique is able to accurately measure both the real part of the index of refraction δ (directly related to electron density) and the attenuation coefficient μ of an object placed in the x-ray beam. Since the atomic number Z (or Zeff for a composite sample) is proportional to these quantities, an elemental map of the effective atomic number can be obtained with the ratio of the phase and the absorption image. The determination of Zeff from refraction and attenuation measurements with Moiré deflectometry could be of high interest in various fields of HED research such as shocked materials and ICF experiments as Zeff is linked, by definition, to the x-ray absorption properties of a specific material. This work is supported by U.S. DoE/NNSA Grant No. 435 DENA0001835.

Methods to mitigate data truncation artifacts in multi-contrast tomosynthesis image reconstructions

NASA Astrophysics Data System (ADS)

Garrett, John; Ge, Yongshuai; Li, Ke; Chen, Guang-Hong

2015-03-01

Differential phase contrast imaging is a promising new image modality that utilizes the refraction rather than the absorption of x-rays to image an object. A Talbot-Lau interferometer may be used to permit differential phase contrast imaging with a conventional medical x-ray source and detector. However, the current size of the gratings fabricated for these interferometers are often relatively small. As a result, data truncation image artifacts are often observed in a tomographic acquisition and reconstruction. When data are truncated in x-ray absorption imaging, the methods have been introduced to mitigate the truncation artifacts. However, the same strategy to mitigate absorption truncation artifacts may not be appropriate for differential phase contrast or dark field tomographic imaging. In this work, several new methods to mitigate data truncation artifacts in a multi-contrast imaging system have been proposed and evaluated for tomosynthesis data acquisitions. The proposed methods were validated using experimental data acquired for a bovine udder as well as several cadaver breast specimens using a benchtop system at our facility.

Pope and Talbot, Inc., Order Partially Granting and Partially Denying Petition for Objection to Title V Operating Permit

EPA Pesticide Factsheets

This document may be of assistance in applying the Title V air operating permit regulations. This document is part of the Title V Petition Database available at www2.epa.gov/title-v-operating-permits/title-v-petition-database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

Optical diffraction interpretation: an alternative to interferometers

NASA Astrophysics Data System (ADS)

Bouillet, S.; Audo, F.; Fréville, S.; Eupherte, L.; Rouyer, C.; Daurios, J.

2015-08-01

The Laser MégaJoule (LMJ) is a French high power laser project that requires thousands of large optical components. The wavefront performances of all those optics are critical to achieve the desired focal spot shape and to limit the hot spots that could damage the components. Fizeau interferometers and interferometric microscopes are the most commonly used tools to cover the whole range of interesting spatial frequencies. Anyway, in some particular cases like diffractive and/or coated and/or aspheric optics, an interferometric set-up becomes very expensive with the need to build a costly reference component or a specific to-the-wavelength designed interferometer. Despite the increasing spatial resolution of Fizeau interferometers, it may even not be enough, if you are trying to access the highest spatial frequencies of a transmitted wavefront for instance. The method we developed is based upon laser beam diffraction intermediate field measurements and their interpretation with a Fourier analysis and the Talbot effect theory. We demonstrated in previous papers that it is a credible alternative to classical methods. In this paper we go further by analyzing main error sources and discussing main practical difficulties.

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

Kagias, M.; Cartier, S.; Wang, Z.

X-ray phase contrast imaging enables the measurement of the electron density of a sample with high sensitivity compared to the conventional absorption contrast. This is advantageous for the study of dose-sensitive samples, in particular, for biological and medical investigations. Recent developments relaxed the requirement for the beam coherence, such that conventional X-ray sources can be used for phase contrast imaging and thus clinical applications become possible. One of the prominent phase contrast imaging methods, Talbot-Lau grating interferometry, is limited by the manufacturing, alignment, and photon absorption of the analyzer grating, which is placed in the beam path in front ofmore » the detector. We propose an alternative improved method based on direct conversion charge integrating detectors, which enables a grating interferometer to be operated without an analyzer grating. Algorithms are introduced, which resolve interference fringes with a periodicity of 4.7 μm recorded with a 25 μm pitch Si microstrip detector (GOTTHARD). The feasibility of the proposed approach is demonstrated by an experiment at the TOMCAT beamline of the Swiss Light Source on a polyethylene sample.« less

Modeling of antihydrogen beam formation for interferometric gravity measurements

NASA Astrophysics Data System (ADS)

Gerber, Sebastian

2018-02-01

In this paper a detailed computational study is performed on the formation of antihydrogen via three-body-recombination of positrons and antiprotons in a Penning trap with a specific focus on formation of a beam of antihydrogen. First, an analytical model is presented to calculate the formation process of the anti-atoms, the yield of the fraction leaving the recombination plasma volume and their angular velocity distribution. This model is then benchmarked against data from different antihydrogen experiments. Subsequently, the flux of antihydrogen towards the axial opening angle of a Penning trap is evaluated for its suitability as input beam into a Talbot-Lau matter interferometer. The layout and optimization of the interferometer to measure the acceleration of antihydrogen in the Earth’s gravitational field is numerically calculated. The simulated results can assist experiments aiming to measure the weak equivalence principle of antimatter as proposed by the AEgIS experiment (Testera et al 2015 Hyperfine Interact. 233 13-20). The presented model can further help in the optimization of beam-like antihydrogen sources for CPT invariance tests of antimatter (Kuroda et al 2014 Nat. Commun. 5 3089).

Numerical Modeling of Shatter Cones Development in Impact Craters

NASA Technical Reports Server (NTRS)

Baratoux, D.; Melosh, H. J.

2003-01-01

Shatter cones are the characteristic forms of rock fractures in impact structures. They have been used for decades as unequivocal fingerprints of meteoritic impacts on Earth. The abundant data about shapes, apical angles, sizes and distributions of shatter cones for many terrestrial impact structures should provide insights for the determination of impact conditions and characteristics of shock waves produced by high-velocity projectiles in geologic media. However, previously proposed models for the formation of shatter cones do not agree with observations. For example, the widely accepted Johnson-Talbot mechanism requires that the longitudinal stress drops to zero between the arrival of the elastic precursor and the main plastic wave. Unfortunately, observations do not support such a drop. A model has been also proposed to explain the striated features on the surface of shatter cones but can not invoked for their conical shape. The mechanism by which shatter cones form thus remains enigmatic to date. In this paper we present a new model for the formation of shatter cones. Our model has been tested by means of numerical simulations using the hydrocodes SALE 2D enhanced with the Grady-Kipp-Melosh fragmentation model.

Kicking atoms with finite duration pulses

NASA Astrophysics Data System (ADS)

Fekete, Julia; Chai, Shijie; Daszuta, Boris; Andersen, Mikkel F.

2016-05-01

The atom optics delta-kicked particle is a paradigmatic system for experimental studies of quantum chaos and classical-quantum correspondence. It consists of a cloud of laser cooled atoms exposed to a periodically pulsed standing wave of far off-resonant laser light. A purely quantum phenomena in such systems are quantum resonances which transfers the atoms into a coherent superposition of largely separated momentum states. Using such large momentum transfer ``beamsplitters'' in atom interferometers may have applications in high precision metrology. The growth in momentum separation cannot be maintained indefinitely due to finite laser power. The largest momentum transfer is achieved by violating the usual delta-kick assumption. Therefore we explore the behavior of the atom optics kicked particle with finite pulse duration. We have developed a semi-classical model which shows good agreement with the full quantum description as well as our experiments. Furthermore we have found a simple scaling law that helps to identify optimal parameters for an atom interferometer. We verify this by measurements of the ``Talbot time'' (a measurement of h/m) which together with other well-known constants constitute a measurement of the fine structure constant.

Effects of fixture rotation on coating uniformity for high-performance optical filter fabrication

NASA Astrophysics Data System (ADS)

Rubin, Binyamin; George, Jason; Singhal, Riju

2018-04-01

Coating uniformity is critical in fabricating high-performance optical filters by various vacuum deposition methods. Simple and planetary rotation systems with shadow masks are used to achieve the required uniformity [J. B. Oliver and D. Talbot, Appl. Optics 45, 13, 3097 (2006); O. Lyngnes, K. Kraus, A. Ode and T. Erguder, in `Method for Designing Coating Thickness Uniformity Shadow Masks for Deposition Systems with a Planetary Fixture', 2014 Technical Conference Proceedings, Optical Coatings, August 13, 2014, DOI: 10.14332/svc14.proc.1817.]. In this work, we discuss the effect of rotation pattern and speed on thickness uniformity in an ion beam sputter deposition system. Numerical modeling is used to determine statistical distribution of random thickness errors in coating layers. The relationship between thickness tolerance and production yield are simulated theoretically and demonstrated experimentally. Production yields for different optical filters produced in an ion beam deposition system with planetary rotation are presented. Single-wavelength and broadband optical monitoring systems were used for endpoint monitoring during filter deposition. Limitations of thickness tolerances that can be achieved in systems with planetary rotation are shown. Paths for improving production yield in an ion beam deposition system are described.

Levitated Optomechanics for Fundamental Physics

NASA Astrophysics Data System (ADS)

Rashid, Muddassar; Bateman, James; Vovrosh, Jamie; Hempston, David; Ulbricht, Hendrik

2015-05-01

Optomechanics with levitated nano- and microparticles is believed to form a platform for testing fundamental principles of quantum physics, as well as find applications in sensing. We will report on a new scheme to trap nanoparticles, which is based on a parabolic mirror with a numerical aperture of 1. Combined with achromatic focussing, the setup is a cheap and readily straightforward solution to trapping nanoparticles for further study. Here, we report on the latest progress made in experimentation with levitated nanoparticles; these include the trapping of 100 nm nanodiamonds (with NV-centres) down to 1 mbar as well as the trapping of 50 nm Silica spheres down to 10?4 mbar without any form of feedback cooling. We will also report on the progress to implement feedback stabilisation of the centre of mass motion of the trapped particle using digital electronics. Finally, we argue that such a stabilised particle trap can be the particle source for a nanoparticle matterwave interferometer. We will present our Talbot interferometer scheme, which holds promise to test the quantum superposition principle in the new mass range of 106 amu. EPSRC, John Templeton Foundation.

High contrast laser beam collimation testing using two proximately placed holographic optical elements

NASA Astrophysics Data System (ADS)

Rajkumar; Dubey, Rajiv; Debnath, Sanjit K.; Chhachhia, D. P.

2018-05-01

Accuracy in laser beam collimation is very important in systems used for precision measurements. The present work reports a technique for collimation testing of laser beams using two proximately placed holographic optical elements (HOEs). The required HOEs are designed and fabricated such that upon illumination with the test beam, they release two laterally sheared wavefronts, at desired angles from the directly transmitted beam, that superimpose each other to generate straight interference fringes. Deviation from the collimation of the test beam results in orientation of these otherwise horizontal fringes. The novelty of this setup comes from the fact that HOEs are lightweight, as well as easy to fabricate as compared to conventional wedge plates used for collimation testing, and generate high contrast fringes compared to other interferometry, holography, Talbot and Moiré based techniques in a compact manner. The proposed technique is experimentally validated by measuring the orientation of fringes by an angle of 16.4° when a collimating lens of focal length 200 mm is defocused by 600 μm. The accuracy in the setting of this collimation position is obtained to be 10 μm.

Noise in x-ray grating-based phase-contrast imaging

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

Weber, Thomas; Bartl, Peter; Bayer, Florian

Purpose: Grating-based x-ray phase-contrast imaging is a fast developing new modality not only for medical imaging, but as well for other fields such as material sciences. While these many possible applications arise, the knowledge of the noise behavior is essential. Methods: In this work, the authors used a least squares fitting algorithm to calculate the noise behavior of the three quantities absorption, differential phase, and dark-field image. Further, the calculated error formula of the differential phase image was verified by measurements. Therefore, a Talbot interferometer was setup, using a microfocus x-ray tube as source and a Timepix detector for photonmore » counting. Additionally, simulations regarding this topic were performed. Results: It turned out that the variance of the reconstructed phase is only dependent of the total number of photons used to generate the phase image and the visibility of the experimental setup. These results could be evaluated in measurements as well as in simulations. Furthermore, the correlation between absorption and dark-field image was calculated. Conclusions: These results provide the understanding of the noise characteristics of grating-based phase-contrast imaging and will help to improve image quality.« less

Noise in x-ray grating-based phase-contrast imaging.

PubMed

Weber, Thomas; Bartl, Peter; Bayer, Florian; Durst, Jürgen; Haas, Wilhelm; Michel, Thilo; Ritter, André; Anton, Gisela

2011-07-01

Grating-based x-ray phase-contrast imaging is a fast developing new modality not only for medical imaging, but as well for other fields such as material sciences. While these many possible applications arise, the knowledge of the noise behavior is essential. In this work, the authors used a least squares fitting algorithm to calculate the noise behavior of the three quantities absorption, differential phase, and dark-field image. Further, the calculated error formula of the differential phase image was verified by measurements. Therefore, a Talbot interferometer was setup, using a microfocus x-ray tube as source and a Timepix detector for photon counting. Additionally, simulations regarding this topic were performed. It turned out that the variance of the reconstructed phase is only dependent of the total number of photons used to generate the phase image and the visibility of the experimental setup. These results could be evaluated in measurements as well as in simulations. Furthermore, the correlation between absorption and dark-field image was calculated. These results provide the understanding of the noise characteristics of grating-based phase-contrast imaging and will help to improve image quality.

Creating and Sustaining Secondary Schools' Success: Sandfields, Cwmtawe, and the Neath-Port Talbot Local Authority's High Reliability Schools Reform

ERIC Educational Resources Information Center

Stringfield, Sam; Reynolds, David; Schaffer, Eugene

2016-01-01

This chapter presents data from a 15-year, mixed-methods school improvement effort. The High Reliability Schools (HRS) reform made use of previous research on school effects and on High Reliability Organizations (HROs). HROs are organizations in various parts of our cultures that are required to operate successfully "the first time, every…

Timing and significance of pathological features in C9orf72 expansion-associated frontotemporal dementia

PubMed Central

Vatsavayai, Sarat C; Yoon, Soo Jin; Gardner, Raquel C; Gendron, Tania F; Vargas, Jose Norberto S; Trujillo, Andrew; Pribadi, Mochtar; Phillips, Joanna J; Gaus, Stephanie E; Hixson, John D; Garcia, Paul A; Rabinovici, Gil D; Coppola, Giovanni; Geschwind, Daniel H; Petrucelli, Leonard; Miller, Bruce L; Seeley, William W

2016-01-01

See Scaber and Talbot (doi:10.1093/aww264) for a scientific commentary on this article. A GGGGCC repeat expansion in C9orf72 leads to frontotemporal dementia and/or amyotrophic lateral sclerosis. Diverse pathological features have been identified, and their disease relevance remains much debated. Here, we describe two illuminating patients with frontotemporal dementia due to the C9orf72 repeat expansion. Case 1 was a 65-year-old female with behavioural variant frontotemporal dementia accompanied by focal degeneration in subgenual anterior cingulate cortex, amygdala, and medial pulvinar thalamus. At autopsy, widespread RNA foci and dipeptide repeat protein inclusions were observed, but TDP-43 pathology was nearly absent, even in degenerating brain regions. Case 2 was a 74-year-old female with atypical frontotemporal dementia–motor neuron disease who underwent temporal lobe resection for epilepsy 5 years prior to her first frontotemporal dementia symptoms. Archival surgical resection tissue contained RNA foci, dipeptide repeat protein inclusions, and loss of nuclear TDP-43 but no TDP-43 inclusions despite florid TDP-43 inclusions at autopsy 8 years after first symptoms. These findings suggest that C9orf72-specific phenomena may impact brain structure and function and emerge before first symptoms and TDP-43 aggregation. PMID:27797809

Assembling mesoscopic particles by various optical schemes

NASA Astrophysics Data System (ADS)

Fournier, Jean-Marc; Rohner, Johann; Jacquot, Pierre; Johann, Robert; Mias, Solon; Salathé, René-P.

2005-08-01

Shaping optical fields is the key issue in the control of optical forces that pilot the manipulation of mesoscopic polarizable dielectric particles. The latter can be positioned according to endless configurations. The scope of this paper is to review and discuss several unusual designs which produce what we think are among some of the most interesting arrangements. The simplest schemes result from interference between two or several coherent light beams, leading to periodic as well as pseudo-periodic arrays of optical traps. Complex assemblages of traps can be created with holographic-type set-ups; this case is widely used by the trapping community. Clusters of traps can also be configured through interferometric-type set-ups or by generating external standing waves by diffractive elements. The particularly remarkable possibilities of the Talbot effect to generate three-dimensional optical lattices and several schemes of self-organization represent further very interesting means for trapping. They will also be described and discussed. in this paper. The mechanisms involved in those trapping schemes do not require the use of high numerical aperture optics; by avoiding the need for bulky microscope objectives, they allow for more physical space around the trapping area to perform experiments. Moreover, very large regular arrays of traps can be manufactured, opening numerous possibilities for new applications.

Improved In vivo Assessment of Pulmonary Fibrosis in Mice using X-Ray Dark-Field Radiography

NASA Astrophysics Data System (ADS)

Yaroshenko, Andre; Hellbach, Katharina; Yildirim, Ali Önder; Conlon, Thomas M.; Fernandez, Isis Enlil; Bech, Martin; Velroyen, Astrid; Meinel, Felix G.; Auweter, Sigrid; Reiser, Maximilian; Eickelberg, Oliver; Pfeiffer, Franz

2015-12-01

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease with a median life expectancy of 4-5 years after initial diagnosis. Early diagnosis and accurate monitoring of IPF are limited by a lack of sensitive imaging techniques that are able to visualize early fibrotic changes at the epithelial-mesenchymal interface. Here, we report a new x-ray imaging approach that directly visualizes the air-tissue interfaces in mice in vivo. This imaging method is based on the detection of small-angle x-ray scattering that occurs at the air-tissue interfaces in the lung. Small-angle scattering is detected with a Talbot-Lau interferometer, which provides the so-called x-ray dark-field signal. Using this imaging modality, we demonstrate-for the first time-the quantification of early pathogenic changes and their correlation with histological changes, as assessed by stereological morphometry. The presented radiography method is significantly more sensitive in detecting morphological changes compared with conventional x-ray imaging, and exhibits a significantly lower radiation dose than conventional x-ray CT. As a result of the improved imaging sensitivity, this new imaging modality could be used in future to reduce the number of animals required for pulmonary research studies.

Predator removal enhances waterbird restoration in Chesapeake Bay (Maryland)

USGS Publications Warehouse

Erwin, R. Michael; McGowan, Peter C.; Reese, Jan

2011-01-01

This report represents an update to an earlier report(Erwin et al. 2007a) on wildlife restoration on the largest dredge material island project in the United States underway in Talbot County, Maryland (Figure 1) in the mid–Chesapeake Bay region, referred to as the Paul Sarbanes Ecosystem Restoration Project at Poplar Island (www.nab.usace.army.mil/projects/Maryland/PoplarIsland/documents.html). An important component of this largescale restoration effort focused on water birds, as many of these species have undergone significant declines in the Chesapeake region over the past 30 years (Erwin et al. 2007b). The priority waterbird species include common terns (Sterna hirundo), least terns (S. antillarum), snowy egrets (Egretta thula), and ospreys (Pandion haliaetus). Although significant numbers of common terns (more than 800 pairs in 2003), least terns (62 pairs in 2003), snowy egrets (50 or more pairs by 2005), and ospreys (7 to 10 pairs) have nested on Poplar Island since early 2000, tern productivity especially had been strongly limited by a combination of red fox (Vulpes vulpes) and great horned owl (Bubo virginianus) predation. Fox trapping began in 2004, and four were removed that year; no more evidence of fox presence was found in 2005 or subsequently. The owls proved to be more problematic.

Non-invasive Differentiation of Kidney Stone Types using X-ray Dark-Field Radiography

PubMed Central

Scherer, Kai; Braig, Eva; Willer, Konstantin; Willner, Marian; Fingerle, Alexander A.; Chabior, Michael; Herzen, Julia; Eiber, Matthias; Haller, Bernhard; Straub, Michael; Schneider, Heike; Rummeny, Ernst J.; Noël, Peter B.; Pfeiffer, Franz

2015-01-01

Treatment of renal calculi is highly dependent on the chemical composition of the stone in question, which is difficult to determine using standard imaging techniques. The objective of this study is to evaluate the potential of scatter-sensitive X-ray dark-field radiography to differentiate between the most common types of kidney stones in clinical practice. Here, we examine the absorption-to-scattering ratio of 118 extracted kidney stones with a laboratory Talbot-Lau Interferometer. Depending on their chemical composition, microscopic growth structure and morphology the various types of kidney stones show strongly varying, partially opposite contrasts in absorption and dark-field imaging. By assessing the microscopic calculi morphology with high resolution micro-computed tomography measurements, we illustrate the dependence of dark-field signal strength on the respective stone type. Finally, we utilize X-ray dark-field radiography as a non-invasive, highly sensitive (100%) and specific (97%) tool for the differentiation of calcium oxalate, uric acid and mixed types of stones, while additionally improving the detectability of radio-lucent calculi. We prove clinical feasibility of the here proposed method by accurately classifying renal stones, embedded within a fresh pig kidney, using dose-compatible measurements and a quick and simple visual inspection. PMID:25873414

Iranian and Swedish adolescents: differences in personality traits and well-being

PubMed Central

Nima, Ali A.; Sikström, Sverker; Archer, Trevor

2013-01-01

Introduction. This study addresses the need to further contextualize research on well-being (e.g., Kjell, 2011) in terms of cross-cultural aspects of personality traits among adolescents and by examining two different conceptualizations of well-being: subjective well-being (i.e., life satisfaction, positive and negative affect) and psychological well-being (i.e., positive relations with others, environmental mastery, self-acceptance, autonomy, personal growth, and life purpose). Methods. Iranian (N = 122, mean age 15.23 years) and Swedish (N = 109, mean age 16.69 years) adolescents were asked to fill out a Big Five personality test, as well as questionnaires assessing subjective well-being and psychological well-being. Results. Swedes reported higher subjective and psychological well-being, while Iranians reported higher degree of Agreeableness, Openness and Conscientiousness. Neuroticism and Extraversion did not differ between cultures. Neuroticism was related to well-being within both cultures. Openness was related to well-being only among Iranians, and Extraversion only among Swedes. A mediation analysis within the Swedish sample, the only sample meeting statistical criteria for mediation analysis to be conducted, demonstrated that psychological well-being mediated the relationship between Neuroticism and subjective well-being as well as between Extraversion and subjective well-being. Conclusions. Certain personality traits, such as Extraversion, Openness, and Conscientiousness, relate differently to well-being measures across cultures. Meanwhile, Neuroticism seems to relate similarly across cultures at least with regard to subjective well-being. Furthermore, the results give an indication on how psychological well-being might mediate the relationship between certain personality traits and subjective well-being. Overall, the complexity of the results illustrates the need for more research whilst supporting the importance of contextualizing well-being research

High-energy x-ray grating-based phase-contrast radiography of human anatomy

NASA Astrophysics Data System (ADS)

Horn, Florian; Hauke, Christian; Lachner, Sebastian; Ludwig, Veronika; Pelzer, Georg; Rieger, Jens; Schuster, Max; Seifert, Maria; Wandner, Johannes; Wolf, Andreas; Michel, Thilo; Anton, Gisela

2016-03-01

X-ray grating-based phase-contrast Talbot-Lau interferometry is a promising imaging technology that has the potential to raise soft tissue contrast in comparison to conventional attenuation-based imaging. Additionally, it is sensitive to attenuation, refraction and scattering of the radiation and thus provides complementary and otherwise inaccessible information due to the dark-field image, which shows the sub-pixel size granularity of the measured object. Until recent progress the method has been mainly limited to photon energies below 40 keV. Scaling the method to photon energies that are sufficient to pass large and spacious objects represents a challenging task. This is caused by increasing demands regarding the fabrication process of the gratings and the broad spectra that come along with the use of polychromatic X-ray sources operated at high acceleration voltages. We designed a setup that is capable to reach high visibilities in the range from 50 to 120 kV. Therefore, spacious and dense parts of the human body with high attenuation can be measured, such as a human knee. The authors will show investigations on the resulting attenuation, differential phase-contrast and dark-field images. The images experimentally show that X-ray grating-based phase-contrast radiography is feasible with highly absorbing parts of the human body containing massive bones.

Intact Imaging of Human Heart Structure Using X-ray Phase-Contrast Tomography.

PubMed

Kaneko, Yukihiro; Shinohara, Gen; Hoshino, Masato; Morishita, Hiroyuki; Morita, Kiyozo; Oshima, Yoshihiro; Takahashi, Masashi; Yagi, Naoto; Okita, Yutaka; Tsukube, Takuro

2017-02-01

Structural examination of human heart specimens at the microscopic level is a prerequisite for understanding congenital heart diseases. It is desirable not to destroy or alter the properties of such specimens because of their scarcity. However, many of the currently available imaging techniques either destroy the specimen through sectioning or alter the chemical and mechanical properties of the specimen through staining and contrast agent injection. As a result, subsequent studies may not be possible. X-ray phase-contrast tomography is an imaging modality for biological soft tissues that does not destroy or alter the properties of the specimen. The feasibility of X-ray phase-contrast tomography for the structural examination of heart specimens was tested using infantile and fetal heart specimens without congenital diseases. X-ray phase-contrast tomography was carried out at the SPring-8 synchrotron radiation facility using the Talbot grating interferometer at the bending magnet beamline BL20B2 to visualize the structure of five non-pretreated whole heart specimens obtained by autopsy. High-resolution, three-dimensional images were obtained for all specimens. The images clearly showed the myocardial structure, coronary vessels, and conduction bundle. X-ray phase-contrast tomography allows high-resolution, three-dimensional imaging of human heart specimens. Intact imaging using X-ray phase-contrast tomography can contribute to further structural investigation of heart specimens with congenital heart diseases.

Geology of the southernmost Piedmont from Columbus to Junction City, GA

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

Hanley, T.B.

1993-03-01

Mapping in the Piedmont from the Chattahoochee River to Junction City, GA, is critical to understanding contacts with Southern Appalachian outboard terranes, relationships to the Piedmont allochthon, strike slip displacements along major faults and late Paleozoic and post Paleozoic tectonic activity. Three major map units defining a large synform are recognized in western Muscogee County: the North Columbus Migmatite Complex, the Moffitts Mill Schist (MMS), and the Phenix City gneiss. The distinctive but poorly exposed fine grained feldspar augen MMS, which extends at least as far east as Geneva, contains small enclaves of amphibolite and calcsilicate and large enclaves ofmore » lineated granitoid gneiss. Protomylonites and mylonitic gneiss with a N-S to N45E strike are exposed from Geneva to Junction City. Three brecciated quartz dikes transect the area in eastern Muscogee Co. and Talbot Co., converging on Talbotton from the southwest. The northern dike strikes ENE and is associated with an augen schist; the middle dike strikes NE and projects to the southwest deep into Muscogee County as a silicified fracture zone with minor associated granite. The southern dike has a NNE strike and is parallel to and locally silicifies the mylonitic foliation that dominates gneisses to the east. Deflections of the magnetic anomaly patterns to the northeast in the Geneva - Junction City area are parallel to quartz dikes and mylonitic foliations.« less

Aged Tg2576 mice are impaired on social memory and open field habituation tests.

PubMed

Deacon, R M J; Koros, E; Bornemann, K D; Rawlins, J N P

2009-02-11

In a previous publication [Deacon RMJ, Cholerton LL, Talbot K, Nair-Roberts RG, Sanderson DJ, Romberg C, et al. Age-dependent and -independent behavioral deficits in Tg2576 mice. Behav Brain Res 2008;189:126-38] we found that very few cognitive tests were suitable for demonstrating deficits in Tg2576 mice, an amyloid over-expression model of Alzheimer's disease, even at 23 months of age. However, in a retrospective analysis of a separate project on these mice, tests of social memory and open field habituation revealed large cognitive impairments. Controls showed good open field habituation, but Tg2576 mice were hyperactive and failed to habituate. In the test of social memory for a juvenile mouse, controls showed considerably less social investigation on the second meeting, indicating memory of the juvenile, whereas Tg2576 mice did not show this decrement.As a control for olfactory sensitivity, on which social memory relies, the ability to find a food pellet hidden under wood chip bedding was assessed. Tg2576 mice found the pellet as quickly as controls. As this test requires digging ability, this was independently assessed in tests of burrowing and directly observed digging. In line with previous results and the hippocampal dysfunction characteristic of aged Tg2576 mice, they both burrowed and dug less than controls.

Axisymmetric deformation of a poroelastic layer overlying an elastic half-space due to surface loading

NASA Astrophysics Data System (ADS)

Rani, Sunita; Rani, Sunita

2017-11-01

The axisymmetric deformation of a homogeneous, isotropic, poroelastic layer of uniform thickness overlying a homogeneous, isotropic, elastic half-space due to surface loads has been obtained. The fluid and the solid constituents of the porous layer are compressible and the permeability in vertical direction is different from its permeability in horizontal direction. The displacements and pore-pressure are taken as basic state variables. An analytical solution for the pore-pressure, displacements and stresses has been obtained using the Laplace-Hankel transform technique. The case of normal disc loading is discussed in detail. Diffusion of pore-pressure is obtained in the space-time domain. The Laplace inversion is evaluated using the fixed Talbot algorithm and the Hankel inversion using the extended Simpson's rule. Two different models of the Earth have been considered: continental crust model and oceanic crust model. For continental crust model, the layer is assumed to be of Westerly Granite and for the oceanic crust model of Hanford Basalt. The effect of the compressibilities of the fluid as well as solid constituents and anisotropy in permeability has been studied on the diffusion of pore-pressure. Contour maps have been plotted for the diffusion of pore-pressure for both models. It is observed that the pore-pressure changes to compression for the continental crust model with time, which is not true for the oceanic crust.

Bounds on quantum collapse models from matter-wave interferometry: calculational details

NASA Astrophysics Data System (ADS)

Toroš, Marko; Bassi, Angelo

2018-03-01

We present a simple derivation of the interference pattern in matter-wave interferometry predicted by a class of quantum master equations. We apply the obtained formulae to the following collapse models: the Ghirardi-Rimini-Weber (GRW) model, the continuous spontaneous localization (CSL) model together with its dissipative (dCSL) and non-Markovian generalizations (cCSL), the quantum mechanics with universal position localization (QMUPL), and the Diósi-Penrose (DP) model. We discuss the separability of the dynamics of the collapse models along the three spatial directions, the validity of the paraxial approximation, and the amplification mechanism. We obtain analytical expressions both in the far field and near field limits. These results agree with those already derived in the Wigner function formalism. We compare the theoretical predictions with the experimental data from two recent matter-wave experiments: the 2012 far-field experiment of Juffmann T et al (2012 Nat. Nanotechnol. 7 297-300) and the 2013 Kapitza-Dirac-Talbot-Lau (KDTL) near-field experiment of Eibenberger et al (2013 Phys. Chem. Chem. Phys. 15 14696-700). We show the region of the parameter space for each collapse model that is excluded by these experiments. We show that matter-wave experiments provide model-insensitive bounds that are valid for a wide family of dissipative and non-Markovian generalizations.

Arcsecond and Sub-arcsedond Imaging with X-ray Multi-Image Interferometer and Imager for (very) small sattelites

NASA Astrophysics Data System (ADS)

Hayashida, K.; Kawabata, T.; Nakajima, H.; Inoue, S.; Tsunemi, H.

2017-10-01

The best angular resolution of 0.5 arcsec is realized with the X-ray mirror onborad the Chandra satellite. Nevertheless, further better or comparable resolution is anticipated to be difficult in near future. In fact, the goal of ATHENA telescope is 5 arcsec in the angular resolution. We propose a new type of X-ray interferometer consisting simply of an X-ray absorption grating and an X-ray spectral imaging detector, such as X-ray CCDs or new generation CMOS detectors, by stacking the multi images created with the Talbot interferenece (Hayashida et al. 2016). This system, now we call Multi Image X-ray Interferometer Module (MIXIM) enables arcseconds resolution with very small satellites of 50cm size, and sub-arcseconds resolution with small sattellites. We have performed ground experiments, in which a micro-focus X-ray source, grating with pitch of 4.8μm, and 30 μm pixel detector placed about 1m from the source. We obtained the self-image (interferometirc fringe) of the grating for wide band pass around 10keV. This result corresponds to about 2 arcsec resolution for parrallel beam incidence. The MIXIM is usefull for high angular resolution imaging of relatively bright sources. Search for super massive black holes and resolving AGN torus would be the targets of this system.

Ground-water resources of the south metropolitan Atlanta region, Georgia

USGS Publications Warehouse

Clarke, John S.; Peck, Michael F.

1991-01-01

Ground-water resources of the nine county south metropolitan Atlanta region were evaluated in response to an increased demand for water supplies and concern that existing surface water supplies may not be able to meet future supply demands. Previous investigations have suggested that crystalline rock in the study area has low permeability and can not sustain well yields suitable for public supply. However, the reported yield for 406 wells drilled into crystalIine rock units in this area ranged from less than 1 to about 700 gallons per minute, and averaged 43 gallons per minute. The reported flow from 13 springs ranged from 0.5 to 679 gallons per minute. The yield of 43 wells and flow from five springs was reported to exceed 100 gallons per minute. Most of the high-yielding wells and springs were near contact zones between rocks of contrasting lithologic and weathering properties. The high-yielding wells and springs are located in a variety of topographic settings: hillsides, upland draws, and hilltops were most prevalent.The study area, which includes Henry, Fayette, Coweta, Spalding, Lamar, Pike, Meriwether, Upson and Talbot Counties, is within the Piedmont physiographic province except for the southernmost part of Talbot County, which is in the Coastal Plain physiographic province. In the Piedmont, ground-water storage occurs in joints, fractures and other secondary openings in the bedrock, and in pore spaces in the regolith. The most favorable geologic settings for siting highyielding wells are along contact zones between rocks of contrasting lithology and permeability, major zones of fracturing such as the Towaliga and Auchumpkee fault zones, and other numerous shear and microbreccia zones.Although most wells in the study area are from 101 to 300 feet deep, the highest average yields were obtained from wells 51 to 100 feet deep, and 301 to 500 feet deep. Of the wells inventoried, the average diameter of well casing was largest for wells located on hills and

Hydrogeology and soil gas at J-Field, Aberdeen Proving Ground, Maryland

USGS Publications Warehouse

Hughes, W.B.

1993-01-01

Disposal of chemical warfare agents, munitions, and industrial chemicals in J-Field, Aberdeen Proving Ground, Maryland, has contaminated soil, groundwater and surface water. Seven exploratory borings and 38 observation wells were drilled to define the hydrogeologic framework at J-Field and to determine the type, extent, and movement of contaminants. The geologic units beneath J-Field consist of Coastal Plain sediments of the Cretaceous Patapsco Formation and Pleistocene Talbot Formation. The Patapsco Formation contains several laterally discontinuous aquifers and confining units. The Pleistocene deposits were divided into 3 hydrogeologic units--a surficial aquifer, a confining unit, and a confined aquifer. Water in the surficial aquifer flows laterally from topographically high areas to discharge areas in marshes and streams, and vertically to the underlying confined aquifer. In offshore areas, water flows from the deeper confined aquifers upward toward discharge areas in the Gunpowder River and Chesapeake Bay. Analyses of soil-gas samples showed high relative-flux values of chlorinated solvents, phthalates, and hydrocarbons at the toxic-materials disposal area, white-phosphorus disposal area, and riot-control-agent disposal area. The highest flux values were located downgradient of the toxic materials and white phosphorus disposal areas, indicating that groundwater contaminants are moving from source areas beneath the disposal pits toward discharge points in the marshes and estuaries. Elevated relative-flux values were measured upgradient and downgradient of the riot-control agent disposal area, and possibly result from soil and (or) groundwater contamination.

Measurements and simulations analysing the noise behaviour of grating-based X-ray phase-contrast imaging

NASA Astrophysics Data System (ADS)

Weber, T.; Bartl, P.; Durst, J.; Haas, W.; Michel, T.; Ritter, A.; Anton, G.

2011-08-01

In the last decades, phase-contrast imaging using a Talbot-Lau grating interferometer is possible even with a low-brilliance X-ray source. With the potential of increasing the soft-tissue contrast, this method is on its way into medical imaging. For this purpose, the knowledge of the underlying physics of this technique is necessary.With this paper, we would like to contribute to the understanding of grating-based phase-contrast imaging by presenting results on measurements and simulations regarding the noise behaviour of the differential phases.These measurements were done using a microfocus X-ray tube with a hybrid, photon-counting, semiconductor Medipix2 detector. The additional simulations were performed by our in-house developed phase-contrast simulation tool “SPHINX”, combining both wave and particle contributions of the simulated photons.The results obtained by both of these methods show the same behaviour. Increasing the number of photons leads to a linear decrease of the standard deviation of the phase. The number of used phase steps has no influence on the standard deviation, if the total number of photons is held constant.Furthermore, the probability density function (pdf) of the reconstructed differential phases was analysed. It turned out that the so-called von Mises distribution is the physically correct pdf, which was also confirmed by measurements.This information advances the understanding of grating-based phase-contrast imaging and can be used to improve image quality.

Poplar Island Environmental Restoration Project: Challenges in waterbird restoration on an island in Chesapeake Bay

USGS Publications Warehouse

Erwin, R.M.; Miller, J.; Reese, J.G.

2007-01-01

At 460 hectares, the Paul Sarbanes Environmental Restoration Project at Poplar Island, Talbot County, Maryland, represents the largest 'beneficial use' dredged material project of the U. S. Army Corps of Engineers (a cooperative project with Maryland Port Administration). Begun in 1998, the 15-year restoration project will ultimately consist of roughly 220 ha of uplands and 220 ha of tidal wetland habitats, with limited areas of dike roads, perimeter riprap, and unvegetated mudflats. Wetland restoration began in one small section (or 'cell') in 2002, but not all cells will be filled with dredged material until at least 2013. As a major objective of the restoration, six species of waterbirds were identified as 'priority species' for Chesapeake Bay: American black duck (Anas rubripes), snowy egret (Egretta thula), cattle egret (Bubulcus ibis), osprey (Pandion haliaetus), common tern (Sterna hirundo), and least tern (S. antillarum). Monitoring of nesting activities of these species from 2002 to 2005 indicated that all species except black ducks colonized the site rapidly. More than 800 pairs of common terns nested in 2003 to 2004. Because of predation by red fox (Vulpes vulpes) and great horned owl (Bubo virginianus), reproductive success was very low for the terns. Trapping was effective in removing the foxes, and other controls have been applied to opportunistic nesting species including herring gulls (Larus argentatus) and Canada geese (Branta canadensis). An effective public education program on the island has helped address concerns about animal control.

Not All Locations Are Created Equal: Exploring How Adults Hide and Search for Objects

PubMed Central

Legge, Eric L. G.; Spetch, Marcia L.; Cenkner, Andrew; Bulitko, Vadim; Anderson, Craig; Brown, Matthew; Heth, Donald

2012-01-01

Little is known about the strategies people use to effectively hide objects from others, or to search for objects others have hidden. The present research extends a recent investigation of people’s hiding and searching strategies in a simple room with 9 cache location. In the present studies, people hid and searched for three objects under more than 70 floor tiles in complex real and virtual rooms. Experiment 1 replicated several finding of Talbot et al within the more complex real and virtual environments. Specifically, people traveled further from origin and selected more dispersed locations when hiding than when searching. Experiments 2 and 3 showed that: 1) people were attracted to an area of darkness when searching and avoided locations close to a window when hiding, 2) when search attempts were limited to three choices, people searched farther from origin and dispersed their locations more when hiding than when searching, and 3) informing people that they would need to recover their hidden objects altered their hiding behavior and increased recovery accuracy. Across all experiments, consistencies in location preferences emerged, with more preference for the middle of the room during hiding and more preference for corners of the room during searching. Even though the same people participated in both the hiding and searching tasks, it appears that people use different strategies to select hiding places than to search for objects hidden by others. PMID:22606324

Preclinical x-ray dark-field imaging: foreign body detection

NASA Astrophysics Data System (ADS)

Braig, Eva-Maria; Muenzel, Daniela; Fingerle, Alexander; Herzen, Julia; Rummeny, Ernst; Pfeiffer, Franz; Noel, Peter

2017-03-01

The purpose of this study was to evaluate the performance of X-ray dark-field imaging for detection of retained foreign bodies in ex-vivo hands and feet. X-ray dark-field imaging, acquired with a three-grating Talbot-Lau interferometer, has proven to provide access to sub-resolution structures due to small-angle scattering. The study was institutional review board (IRB) approved. Foreign body parts included pieces of wood and metal which were placed in a formalin fixated human ex-vivo hand. The samples were imaged with a grating-based interferometer consisting of a standard microfocus X-ray tube (60 kVp, 100 W) and a Varian 2520-DX detector (pixel size: 127 μm). The attenuation and the dark-field signals provide complementary diagnostic information for this clinical task. With regard to detecting of wooden objects, which are clinically the most relevant, only the dark-field image revealed the locations. The signal is especially strong for dry wood which in comparison is poorly to non-visible in computed tomography. The detection of high atomic-number or dense material and wood-like or porous materials in a single X-ray scan is enabled by the simultaneous acquisition of the conventional attenuation and dark-field signal. Our results reveal that with this approach one can reach a significantly improved sensitivity for detection of foreign bodies, while an easy implementation into the clinical arena is becoming feasible.

Identification of specific sources of airborne particles emitted from within a complex industrial (steelworks) site

NASA Astrophysics Data System (ADS)

Beddows, D. C. S.; Harrison, Roy M.

2018-06-01

A case study is provided of the development and application of methods to identify and quantify specific sources of emissions from within a large complex industrial site. Methods include directional analysis of concentrations, chemical source tracers and correlations with gaseous emissions. Extensive measurements of PM10, PM2.5, trace gases, particulate elements and single particle mass spectra were made at sites around the Port Talbot steelworks in 2012. By using wind direction data in conjunction with real-time or hourly-average pollutant concentration measurements, it has been possible to locate areas within the steelworks associated with enhanced pollutant emissions. Directional analysis highlights the Slag Handling area of the works as the most substantial source of elevated PM10 concentrations during the measurement period. Chemical analyses of air sampled from relevant wind directions is consistent with the anticipated composition of slags, as are single particle mass spectra. Elevated concentrations of PM10 are related to inverse distance from the Slag Handling area, and concentrations increase with increased wind speed, consistent with a wind-driven resuspension source. There also appears to be a lesser source associated with Sinter Plant emissions affecting PM10 concentrations at the Fire Station monitoring site. The results are compared with a ME2 study using some of the same data, and shown to give a clearer view of the location and characteristics of emission sources, including fugitive dusts.

Improved visualization of breast cancer features in multifocal carcinoma using phase-contrast and dark-field mammography: an ex vivo study.

PubMed

Grandl, Susanne; Scherer, Kai; Sztrókay-Gaul, Anikó; Birnbacher, Lorenz; Willer, Konstantin; Chabior, Michael; Herzen, Julia; Mayr, Doris; Auweter, Sigrid D; Pfeiffer, Franz; Bamberg, Fabian; Hellerhoff, Karin

2015-12-01

Conventional X-ray attenuation-based contrast is inherently low for the soft-tissue components of the female breast. To overcome this limitation, we investigate the diagnostic merits arising from dark-field mammography by means of certain tumour structures enclosed within freshly dissected mastectomy samples. We performed grating-based absorption, absolute phase and dark-field mammography of three freshly dissected mastectomy samples containing bi- and multifocal carcinoma using a compact, laboratory Talbot-Lau interferometer. Preoperative in vivo imaging (digital mammography, ultrasound, MRI), postoperative histopathological analysis and ex vivo digital mammograms of all samples were acquired for the diagnostic verification of our results. In the diagnosis of multifocal tumour growth, dark-field mammography seems superior to standard breast imaging modalities, providing a better resolution of small, calcified tumour nodules, demarcation of tumour boundaries with desmoplastic stromal response and spiculated soft-tissue strands extending from an invasive ductal breast cancer. On the basis of selected cases, we demonstrate that dark-field mammography is capable of outperforming conventional mammographic imaging of tumour features in both calcified and non-calcified tumours. Presuming dose optimization, our results encourage further studies on larger patient cohorts to identify those patients that will benefit the most from this promising additional imaging modality. • X-ray dark-field mammography provides significantly improved visualization of tumour features • X-ray dark-field mammography is capable of outperforming conventional mammographic imaging • X-ray dark-field mammography provides imaging sensitivity towards highly dispersed calcium grains.

Coherence properties of blackbody radiation and application to energy harvesting and imaging with nanoscale rectennas

NASA Astrophysics Data System (ADS)

Lerner, Peter B.; Cutler, Paul H.; Miskovsky, Nicholas M.

2015-01-01

Modern technology allows the fabrication of antennas with a characteristic size comparable to the electromagnetic wavelength in the optical region. This has led to the development of new technologies using nanoscale rectifying antennas (rectennas) for solar energy conversion and sensing of terahertz, infrared, and visible radiation. For example, a rectenna array can collect incident radiation from an emitting source and the resulting conversion efficiency and operating characteristics of the device will depend on the spatial and temporal coherence properties of the absorbed radiation. For solar radiation, the intercepted radiation by a micro- or nanoscale array of devices has a relatively narrow spatial and angular distribution. Using the Van Cittert-Zernike theorem, we show that the coherence length (or radius) of solar radiation on an antenna array is, or can be, tens of times larger than the characteristic wavelength of the solar spectrum, i.e., the thermal wavelength, λT=2πℏc/(kBT), which for T=5000 K is about 3 μm. Such an effect is advantageous, making possible the rectification of solar radiation with nanoscale rectenna arrays, whose size is commensurate with the coherence length. Furthermore, we examine the blackbody radiation emitted from an array of antennas at temperature T, which can be quasicoherent and lead to a modified self-image, analogous to the Talbot-Lau self-imaging process but with thermal rather than monochromatic radiation. The self-emitted thermal radiation may be important as a nondestructive means for quality control of the array.

Aberdeen area fire training area hydrologic assessment, Aberdeen Proving Ground. Final report, September 1989-July 1991

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

Whitten, C.B.; Miller, S.P.; Derryberry, N.A.

1992-12-01

In 1986, the US Environmental Protection Agency (EPA) issued a Hazardous Waste Management Permit to Aberdeen Proving Ground (APG), Maryland. The permit required a Resource Conservation and Recovery Act (RCRA) Facility Assessment (RFA) of sites in the Aberdeen Area (AA) of APG. Recommendations from a draft RFA report suggested further investigations at the Fire Training Area (FTA). This study is in response to the recommendations. Three soil borings and twelve groundwater monitor wells were installed. Three rounds of groundwater sampling and analyses were conducted. APG lies in the Coastal Plain Physiographic Province which is underlain by sediments consisting of threemore » major units, the Potomac Group, the Talbot Formation, and Recent (Holocene) sediments. The Lower Cretaceous sediments of the Potomac Group lie unconformably on the older Precambrian rocks. In the early 1960's fire training was initiated and training has been conducted as often as once a week. Trenches were ignited after being filled with oil and water. The exercises concluded in 1989. During the RFA shallow boring soil gas surveys were conducted for volatile organic compound (VOC) contamination at the FTA. Deeper borings were conducted for monitor wells and geologic mapping. Sampling and monitoring of groundwater, surface water, and soils was conducted. Analyses of groundwater from the monitor wells and two supply wells indicate the AFTA is contributing chemical contaminants to the upper aquifer, which is at a depth of approximately 30 feet below ground surface. ....Aberdeen Proving Ground, Maryland, Hydrogeology, Groundwater, Site characterization, Groundwater contamination.« less

Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner.

PubMed

Müller, Mark; Yaroshenko, Andre; Velroyen, Astrid; Bech, Martin; Tapfer, Arne; Pauwels, Bart; Bruyndonckx, Peter; Sasov, Alexander; Pfeiffer, Franz

2015-12-01

In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed.

Differences in coastal subsidence in southern Oregon (USA) during at least six prehistoric megathrust earthquakes

USGS Publications Warehouse

Milker, Yvonne; Nelson, Alan R.; Horton, Benjamin P.; Engelhart, Simon E.; Bradley, Lee-Ann; Witter, Robert C.

2016-01-01

Stratigraphic, sedimentologic (including CT 3D X-ray tomography scans), foraminiferal, and radiocarbon analyses show that at least six of seven abrupt peat-to-mud contacts in cores from a tidal marsh at Talbot Creek (South Slough, Coos Bay), record sudden subsidence (relative sea-level rise) during great megathrust earthquakes at the Cascadia subduction zone. Data for one contact are insufficient to infer whether or not it records a great earthquake—it may also have formed through local, non-seismic, hydrographic processes. To estimate the amount of subsidence marked by each contact, we expanded a previous regional modern foraminiferal dataset to 174 samples from six Oregon estuaries. Using a transfer function derived from the new dataset, estimates of coseismic subsidence across the six earthquake contacts vary from 0.31 m to 0.75 m. Comparison of subsidence estimates for three contacts in adjacent cores shows within-site differences of ≤0.10 m, about half the ±0.22 m error, although some estimates may be minimums due to uncertain ecological preferences for Balticammina pseudomacrescens in brackish environments and almost monospecific assemblages of Miliammina fusca on tidal flats. We also account for the influence of taphonomic processes, such as infiltration of mud with mixed foraminiferal assemblages into peat, on subsidence estimates. Comparisons of our subsidence estimates with values for correlative contacts at other Oregon sites suggest that some of our estimates are minimums and that Cascadia's megathrust earthquake ruptures have been heterogeneous over the past 3500 years.

Refractive index degeneration in older lenses: A potential functional correlate to structural changes that underlie cataract formation.

PubMed

Bahrami, Mehdi; Hoshino, Masato; Pierscionek, Barbara; Yagi, Naoto; Regini, Justyn; Uesugi, Kentaro

2015-11-01

A major structure/function relationship in the eye lens is that between the constituent proteins, the crystallins and the optical property of refractive index. Structural breakdown that leads to cataract has been investigated in a number of studies; the concomitant changes in the optics, namely increases in light attenuation have also been well documented. Specific changes in the refractive index gradient that cause such attenuation, however, are not well studied because previous methods of measuring refractive index require transparent samples. The X-ray Talbot interferometric method using synchrotron radiation allows for measurement of fine changes in refractive index through lenses with opacities. The findings of this study on older human lenses show disruptions to the refractive index gradient and in the refractive index contours. These disruptions are linked to location in the lens and occur in polar regions, along or close to the equatorial plane or in lamellar-like formations. The disruptions that are seen in the polar regions manifest branching formations that alter with progression through the lens with some similarity to lens sutures. This study shows how the refractive index gradient, which is needed to maintain image quality of the eye, may be disturbed and that this can occur in a number of distinct ways. These findings offer insight into functional changes to a major optical parameter in older lenses. Further studies are needed to elicit how these may be related to structural degenerations reported in the literature. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

The eye lens: age-related trends and individual variations in refractive index and shape parameters.

PubMed

Pierscionek, Barbara; Bahrami, Mehdi; Hoshino, Masato; Uesugi, Kentaro; Regini, Justyn; Yagi, Naoto

2015-10-13

The eye lens grows throughout life by cell accrual on its surface and can change shape to adjust the focussing power of the eye. Varying concentrations of proteins in successive cell layers create a refractive index gradient. The continued growth of the lens and age-related changes in proteins render it less able to alter shape with loss of capacity by the end of the sixth decade of life. Growth and protein ageing alter the refractive index but as accurate measurement of this parameter is difficult, the nature of such alterations remains uncertain. The most accurate method to date for measuring refractive index in intact lenses has been developed at the SPring-8 synchrotron. The technique, based on Talbot interferometry, has an X-ray source and was used to measure refractive index in sixty-six human lenses, aged from 16 to 91 years. Height and width were measured for forty-five lenses. Refractive index contours show decentration in some older lenses but individual variations mask age-related trends. Refractive index profiles along the optic axis have relatively flat central sections with distinct micro-fluctuations and a steep gradient in the cortex but do not exhibit an age-related trend. The refractive index profiles in the equatorial aspect show statistical significance with age, particularly for lenses below the age of sixty that had capacity to alter shape in vivo. The maximum refractive index in the lens centre decreases slightly with age with considerable scatter in the data and there are age-related variations in sagittal thickness and equatorial height.

Slit-scanning differential x-ray phase-contrast mammography: proof-of-concept experimental studies.

PubMed

Koehler, Thomas; Daerr, Heiner; Martens, Gerhard; Kuhn, Norbert; Löscher, Stefan; van Stevendaal, Udo; Roessl, Ewald

2015-04-01

The purpose of this work is to investigate the feasibility of grating-based, differential phase-contrast, full-field digital mammography (FFDM) in terms of the requirements for field-of-view (FOV), mechanical stability, and scan time. A rigid, actuator-free Talbot interferometric unit was designed and integrated into a state-of-the-art x-ray slit-scanning mammography system, namely, the Philips MicroDose L30 FFDM system. A dedicated phase-acquisition and phase retrieval method was developed and implemented that exploits the redundancy of the data acquisition inherent to the slit-scanning approach to image generation of the system. No modifications to the scan arm motion control were implemented. The authors achieve a FOV of 160 × 196 mm consisting of two disjoint areas measuring 77 × 196 mm with a gap of 6 mm between them. Typical scanning times vary between 10 and 15 s and dose levels are lower than typical FFDM doses for conventional scans with identical acquisition parameters due to the presence of the source-grating G0. Only minor to moderate artifacts are observed in the three reconstructed images, indicating that mechanical vibrations induced by other system components do not prevent the use of the platform for phase contrast imaging. To the best of our knowledge, this is the first attempt to integrate x-ray gratings hardware into a clinical mammography unit. The results demonstrate that a scanning differential phase contrast FFDM system that meets the requirements of FOV, stability, scan time, and dose can be build.

State-of-the-art Nanofabrication in Catalysis.

PubMed

Karim, Waiz; Tschupp, Simon A; Herranz, Juan; Schmidt, Thomas J; Ekinci, Yasin; van Bokhovenac, Jeroen A

2017-04-26

We present recent developments in top-down nanofabrication that have found application in catalysis research. To unravel the complexity of catalytic systems, the design and use of models with control of size, morphology, shape and inter-particle distances is a necessity. The study of well-defined and ordered nanoparticles on a support contributes to the understanding of complex phenomena that govern reactions in heterogeneous and electro-catalysis. We review the strengths and limitations of different nanolithography methods such as electron beam lithography (EBL), photolithography, extreme ultraviolet (EUV) lithography and colloidal lithography for the creation of such highly tunable catalytic model systems and their applications in catalysis. Innovative strategies have enabled particle sizes reaching dimensions below 10 nm. It is now possible to create pairs of particles with distance controlled with an extremely high precision in the order of one nanometer. We discuss our approach to study these model systems at the single-particle level using X-ray absorption spectroscopy and show new ways to fabricate arrays of single nanoparticles or nanoparticles in pairs over a large area using EBL and EUV-achromatic Talbot lithography. These advancements have provided new insights into the active sites in metal catalysts and enhanced the understanding of the role of inter-particle interactions and catalyst supports, such as in the phenomenon of hydrogen spillover. We present a perspective on future directions for employing top-down nanofabrication in heterogeneous and electrocatalysis. The rapid development in nanofabrication and characterization methods will continue to have an impact on understanding of complex catalytic processes.

The eye lens: age-related trends and individual variations in refractive index and shape parameters

PubMed Central

Pierscionek, Barbara; Bahrami, Mehdi; Hoshino, Masato; Uesugi, Kentaro; Regini, Justyn; Yagi, Naoto

2015-01-01

The eye lens grows throughout life by cell accrual on its surface and can change shape to adjust the focussing power of the eye. Varying concentrations of proteins in successive cell layers create a refractive index gradient. The continued growth of the lens and age-related changes in proteins render it less able to alter shape with loss of capacity by the end of the sixth decade of life. Growth and protein ageing alter the refractive index but as accurate measurement of this parameter is difficult, the nature of such alterations remains uncertain. The most accurate method to date for measuring refractive index in intact lenses has been developed at the SPring-8 synchrotron. The technique, based on Talbot interferometry, has an X-ray source and was used to measure refractive index in sixty-six human lenses, aged from 16 to 91 years. Height and width were measured for forty-five lenses. Refractive index contours show decentration in some older lenses but individual variations mask age-related trends. Refractive index profiles along the optic axis have relatively flat central sections with distinct micro-fluctuations and a steep gradient in the cortex but do not exhibit an age-related trend. The refractive index profiles in the equatorial aspect show statistical significance with age, particularly for lenses below the age of sixty that had capacity to alter shape in vivo. The maximum refractive index in the lens centre decreases slightly with age with considerable scatter in the data and there are age-related variations in sagittal thickness and equatorial height. PMID:26416418

Innovation and fusion of x-ray and optical tomography for mouse studies of breast cancer

NASA Astrophysics Data System (ADS)

Wang, Ge; Cong, Wenxiang; Yang, Qingsong; Pian, Qi; Zhu, Shouping; Liang, Jimin; Barroso, Margarida; Intes, Xavier

2016-10-01

For early detection and targeted therapy, receptor expression profiling is instrumental to classifying breast cancer into sub-groups. In particular, human epidermal growth factor receptor 2 (HER2) expression has been shown to have both prognostic and predictive values. Recently, an increasingly more complex view of HER2 in breast cancer has emerged from genome sequencing that highlights the role of inter- and intra-tumor heterogeneity in therapy resistance. Studies on such heterogeneity demand high-content, high-resolution functional and molecular imaging in vivo, which cannot be achieved using any single imaging tool. Clearly, there is a critical need to develop a multimodality approach for breast cancer imaging. Since 2006, grating-based x-ray imaging has been developed for much-improved x-ray images. In 2014, the demonstration of fluorescence molecular tomography (FMT) guided by x-ray grating-based micro-CT was reported with encouraging results and major drawbacks. In this paper, we propose to integrate grating-based x-ray tomography (GXT) and high-dimensional optical tomography (HOT) into the first-of-its-kind truly-fused GXT-HOT (pronounced as "Get Hot") system for imaging of breast tumor heterogeneity, HER2 expression and dimerization, and therapeutic response. The primary innovation lies in developing a brand-new high-content, high-throughput x-ray optical imager based on several contemporary techniques to have MRI-type soft tissue contrast, PET-like sensitivity and specificity, and micro-CT-equivalent resolution. This system consists of two orthogonal x-ray Talbot-Lau interferometric imaging chains and a hyperspectral time-resolved single-pixel optical imager. Both the system design and pilot results will be reported in this paper, along with relevant issues under further investigation.

Hydrogeologic setting, hydraulic properties, and ground-water flow at the O-Field area of Aberdeen Proving Ground, Maryland

USGS Publications Warehouse

Banks, W.S.; Smith, B.S.; Donnelly, C.A.

1996-01-01

The U.S. Army disposed chemical agents, laboratory materials, and unexploded ordnance at O-Field in the Edgewood area of Aberdeen Proving Ground, Maryland, from before World War II until at least the 1950's. Soil, ground water, surface water,and wetland sediments in the O-Field area were contaminated from the disposal activity. A ground-water-flow model of the O-Field area was constructed by the U.S. Geological Survey (USGS) in 1989 to simulate flow in the central and southern part of the Gunpowder Neck. The USGS began an additional study of the contamination in the O-Field area in cooperation with the U.S. Army in 1990 to (1) further define the hydrogeologic framework of the O-Field area, (2) characterize the hydraulic properties of the aquifers and confining units, and (3) define ground-water flow paths at O-Field based on the current data and simulations of ground-water flow. A water-table aquifer, an upper confining unit, and an upper confined aquifer comprise the shallow ground-water aquifer system of the O-Field area. A lower confining unit, through which ground-water movement is negligible, is considered a lower boundary to the shallow aquifer system. These units are all part of the Pleistocene Talbot Formation. The model developed in the previous study was redesigned using the data collected during this study and emphasized New O-Field. The current steady-state model was calibrated to water levels of June 1993. The rate of ground-water flow calculated by the model was approximately 0.48 feet per day (ft/d) and the rate determined from chlorofluorocarbon dates was approximately 0.39 ft/d.

Cell force mapping using a double-sided micropillar array based on the moiré fringe method

NASA Astrophysics Data System (ADS)

Zhang, F.; Anderson, S.; Zheng, X.; Roberts, E.; Qiu, Y.; Liao, R.; Zhang, X.

2014-07-01

The mapping of traction forces is crucial to understanding the means by which cells regulate their behavior and physiological function to adapt to and communicate with their local microenvironment. To this end, polymeric micropillar arrays have been used for measuring cell traction force. However, the small scale of the micropillar deflections induced by cell traction forces results in highly inefficient force analyses using conventional optical approaches; in many cases, cell forces may be below the limits of detection achieved using conventional microscopy. To address these limitations, the moiré phenomenon has been leveraged as a visualization tool for cell force mapping due to its inherent magnification effect and capacity for whole-field force measurements. This Letter reports an optomechanical cell force sensor, namely, a double-sided micropillar array (DMPA) made of poly(dimethylsiloxane), on which one side is employed to support cultured living cells while the opposing side serves as a reference pattern for generating moiré patterns. The distance between the two sides, which is a crucial parameter influencing moiré pattern contrast, is predetermined during fabrication using theoretical calculations based on the Talbot effect that aim to optimize contrast. Herein, double-sided micropillar arrays were validated by mapping mouse embryo fibroblast contraction forces and the resulting force maps compared to conventional microscopy image analyses as the reference standard. The DMPA-based approach precludes the requirement for aligning two independent periodic substrates, improves moiré contrast, and enables efficient moiré pattern generation. Furthermore, the double-sided structure readily allows for the integration of moiré-based cell force mapping into microfabricated cell culture environments or lab-on-a-chip devices.

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

Müller, Mark, E-mail: mark-mueller@ph.tum.de; Yaroshenko, Andre; Velroyen, Astrid

In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal andmore » noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed.« less

An efficient and guaranteed stable numerical method for continuous modeling of infiltration and redistribution with a shallow dynamic water table

NASA Astrophysics Data System (ADS)

Lai, Wencong; Ogden, Fred L.; Steinke, Robert C.; Talbot, Cary A.

2015-03-01

We have developed a one-dimensional numerical method to simulate infiltration and redistribution in the presence of a shallow dynamic water table. This method builds upon the Green-Ampt infiltration with Redistribution (GAR) model and incorporates features from the Talbot-Ogden (T-O) infiltration and redistribution method in a discretized moisture content domain. The redistribution scheme is more physically meaningful than the capillary weighted redistribution scheme in the T-O method. Groundwater dynamics are considered in this new method instead of hydrostatic groundwater front. It is also computationally more efficient than the T-O method. Motion of water in the vadose zone due to infiltration, redistribution, and interactions with capillary groundwater are described by ordinary differential equations. Numerical solutions to these equations are computationally less expensive than solutions of the highly nonlinear Richards' (1931) partial differential equation. We present results from numerical tests on 11 soil types using multiple rain pulses with different boundary conditions, with and without a shallow water table and compare against the numerical solution of Richards' equation (RE). Results from the new method are in satisfactory agreement with RE solutions in term of ponding time, deponding time, infiltration rate, and cumulative infiltrated depth. The new method, which we call "GARTO" can be used as an alternative to the RE for 1-D coupled surface and groundwater models in general situations with homogeneous soils with dynamic water table. The GARTO method represents a significant advance in simulating groundwater surface water interactions because it very closely matches the RE solution while being computationally efficient, with guaranteed mass conservation, and no stability limitations that can affect RE solvers in the case of a near-surface water table.

Kernel learning at the first level of inference.

PubMed

Cawley, Gavin C; Talbot, Nicola L C

2014-05-01

Kernel learning methods, whether Bayesian or frequentist, typically involve multiple levels of inference, with the coefficients of the kernel expansion being determined at the first level and the kernel and regularisation parameters carefully tuned at the second level, a process known as model selection. Model selection for kernel machines is commonly performed via optimisation of a suitable model selection criterion, often based on cross-validation or theoretical performance bounds. However, if there are a large number of kernel parameters, as for instance in the case of automatic relevance determination (ARD), there is a substantial risk of over-fitting the model selection criterion, resulting in poor generalisation performance. In this paper we investigate the possibility of learning the kernel, for the Least-Squares Support Vector Machine (LS-SVM) classifier, at the first level of inference, i.e. parameter optimisation. The kernel parameters and the coefficients of the kernel expansion are jointly optimised at the first level of inference, minimising a training criterion with an additional regularisation term acting on the kernel parameters. The key advantage of this approach is that the values of only two regularisation parameters need be determined in model selection, substantially alleviating the problem of over-fitting the model selection criterion. The benefits of this approach are demonstrated using a suite of synthetic and real-world binary classification benchmark problems, where kernel learning at the first level of inference is shown to be statistically superior to the conventional approach, improves on our previous work (Cawley and Talbot, 2007) and is competitive with Multiple Kernel Learning approaches, but with reduced computational expense. Copyright © 2014 Elsevier Ltd. All rights reserved.

Genetic characterization of brown bears of the Kodiak Archipelago

USGS Publications Warehouse

Talbot, Sandra L.; Gust, Judy R.; Sage, George K.; Fischbach, Anthony S.; Amstrup, Kristin S.; Leacock, William; Van Daele, Larry

2006-01-01

Here we examine genetic characteristics of brown bears of Kodiak and Afognak islands, using 14 variable nuclear microsatellite loci and nucleotide sequence information including the hypervariable domain I of the mtDNA control region (Wakely 1993). Because these markers, or a subset of them, have been used to characterize brown bears of the Kenai Peninsula (Jackson et al. 2005), Katmai National Park, Seward Peninsula, and nine other populations in Alaska (Talbot, unpublished data), we compared levels of genetic diversity and relationships among populations when possible. In addition, we obtained preliminary comparative information from class II DQA and DQB genes of the brown bear MHC, to examine levels of variation at this important immunology-mediating supergene. These data were used to answer the following questions: 1) are earlier findings of extremely low levels of variability at nuclear (biparentallyinherited) microsatellite loci from a small geographic area (Paetkau et al. 1998b) representative of Kodiak Archipelago populations as a whole? 2) Is the level and type of variation at the maternally-inherited mtDNA lower, or similar to, levels found in other populations in Alaska? 3) Is there concordance between low levels of genetic variation observed at neutral markers with levels of variation observed at functional genes? 4) Is there population substructuring within Kodiak and Afognak islands? 5) What is the connectivity between populations on Afognak Island and Kodiak Island? 6) What are the phylogeographic relationships between bears of the Kodiak Archipelago with brown bears on mainland Alaskan and other western Beringian populations? We also test whether these markers will provide an appropriate baseline for designing genetic tagging studies for use in future research and management activities, such as mark-recapture efforts, on the Refuge.

Experimentally enhanced model-based deconvolution of propagation-based phase-contrast data

NASA Astrophysics Data System (ADS)

Pichotka, M.; Palma, K.; Hasn, S.; Jakubek, J.; Vavrik, D.

2016-12-01

In recent years phase-contrast has become a much investigated modality in radiographic imaging. The radiographic setups employed in phase-contrast imaging are typically rather costly and complex, e.g. high performance Talbot-Laue interferometers operated at synchrotron light sources. In-line phase-contrast imaging states the most pedestrian approach towards phase-contrast enhancement. Utilizing small angle deflection within the imaged sample and the entailed interference of the deflected and un-deflected beam during spatial propagation, in-line phase-contrast imaging only requires a well collimated X-ray source with a high contrast & high resolution detector. Employing high magnification the above conditions are intrinsically fulfilled in cone-beam micro-tomography. As opposed of 2D imaging, where contrast enhancement is generally considered beneficial, in tomographic modalities the in-line phase-contrast effect can be quite a nuisance since it renders the inverse problem posed by tomographic reconstruction inconsistent, thus causing reconstruction artifacts. We present an experimentally enhanced model-based approach to disentangle absorption and in-line phase-contrast. The approach employs comparison of transmission data to a system model computed iteratively on-line. By comparison of the forward model to absorption data acquired in continuous rotation strong local deviations of the data residual are successively identified as likely candidates for in-line phase-contrast. By inducing minimal vibrations (few mrad) to the sample around the peaks of such deviations the transmission signal can be decomposed into a constant absorptive fraction and an oscillating signal caused by phase-contrast which again allows to generate separate maps for absorption and phase-contrast. The contributions of phase-contrast and the corresponding artifacts are subsequently removed from the tomographic dataset. In principle, if a 3D handling of the sample is available, this method also

From powerful research platform for industrial EUV photoresist development, to world record resolution by photolithography: EUV interference lithography at the Paul Scherrer Institute

NASA Astrophysics Data System (ADS)

Buitrago, Elizabeth; Fallica, Roberto; Fan, Daniel; Karim, Waiz; Vockenhuber, Michaela; van Bokhoven, Jeroen A.; Ekinci, Yasin

2016-09-01

Extreme ultraviolet interference lithography (EUV-IL, λ = 13.5 nm) has been shown to be a powerful technique not only for academic, but also for industrial research and development of EUV materials due to its relative simplicity yet record high-resolution patterning capabilities. With EUV-IL, it is possible to pattern high-resolution periodic images to create highly ordered nanostructures that are difficult or time consuming to pattern by electron beam lithography (EBL) yet interesting for a wide range of applications such as catalysis, electronic and photonic devices, and fundamental materials analysis, among others. Here, we will show state-of the-art research performed using the EUV-IL tool at the Swiss Light Source (SLS) synchrotron facility in the Paul Scherrer Institute (PSI). For example, using a grating period doubling method, a diffraction mask capable of patterning a world record in photolithography of 6 nm half-pitch (HP), was produced. In addition to the description of the method, we will give a few examples of applications of the technique. Well-ordered arrays of suspended silicon nanowires down to 6.5 nm linewidths have been fabricated and are to be studied as field effect transistors (FETs) or biosensors, for instance. EUV achromatic Talbot lithography (ATL), another interference scheme that utilizes a single grating, was shown to yield well-defined nanoparticles over large-areas with high uniformity presenting great opportunities in the field of nanocatalysis. EUV-IL is in addition, playing a key role in the future introduction of EUV lithography into high volume manufacturing (HVM) of semiconductor devices for the 7 and 5 nm logic node (16 nm and 13 nm HP, respectively) and beyond while the availability of commercial EUV-tools is still very much limited for research.

Quantum Optics in Phase Space

NASA Astrophysics Data System (ADS)

Schleich, Wolfgang P.

2001-04-01

Quantum Optics in Phase Space provides a concise introduction to the rapidly moving field of quantum optics from the point of view of phase space. Modern in style and didactically skillful, Quantum Optics in Phase Space prepares students for their own research by presenting detailed derivations, many illustrations and a large set of workable problems at the end of each chapter. Often, the theoretical treatments are accompanied by the corresponding experiments. An exhaustive list of references provides a guide to the literature. Quantum Optics in Phase Space also serves advanced researchers as a comprehensive reference book. Starting with an extensive review of the experiments that define quantum optics and a brief summary of the foundations of quantum mechanics the author Wolfgang P. Schleich illustrates the properties of quantum states with the help of the Wigner phase space distribution function. His description of waves ala WKB connects semi-classical phase space with the Berry phase. These semi-classical techniques provide deeper insight into the timely topics of wave packet dynamics, fractional revivals and the Talbot effect. Whereas the first half of the book deals with mechanical oscillators such as ions in a trap or atoms in a standing wave the second half addresses problems where the quantization of the radiation field is of importance. Such topics extensively discussed include optical interferometry, the atom-field interaction, quantum state preparation and measurement, entanglement, decoherence, the one-atom maser and atom optics in quantized light fields. Quantum Optics in Phase Space presents the subject of quantum optics as transparently as possible. Giving wide-ranging references, it enables students to study and solve problems with modern scientific literature. The result is a remarkably concise yet comprehensive and accessible text- and reference book - an inspiring source of information and insight for students, teachers and researchers alike.

AEgIS at ELENA: outlook for physics with a pulsed cold antihydrogen beam

NASA Astrophysics Data System (ADS)

Doser, M.; Aghion, S.; Amsler, C.; Bonomi, G.; Brusa, R. S.; Caccia, M.; Caravita, R.; Castelli, F.; Cerchiari, G.; Comparat, D.; Consolati, G.; Demetrio, A.; Di Noto, L.; Evans, C.; Fanì, M.; Ferragut, R.; Fesel, J.; Fontana, A.; Gerber, S.; Giammarchi, M.; Gligorova, A.; Guatieri, F.; Haider, S.; Hinterberger, A.; Holmestad, H.; Kellerbauer, A.; Khalidova, O.; Krasnický, D.; Lagomarsino, V.; Lansonneur, P.; Lebrun, P.; Malbrunot, C.; Mariazzi, S.; Marton, J.; Matveev, V.; Mazzotta, Z.; Müller, S. R.; Nebbia, G.; Nedelec, P.; Oberthaler, M.; Pacifico, N.; Pagano, D.; Penasa, L.; Petracek, V.; Prelz, F.; Prevedelli, M.; Rienaecker, B.; Robert, J.; Røhne, O. M.; Rotondi, A.; Sandaker, H.; Santoro, R.; Smestad, L.; Sorrentino, F.; Testera, G.; Tietje, I. C.; Widmann, E.; Yzombard, P.; Zimmer, C.; Zmeskal, J.; Zurlo, N.

2018-03-01

The efficient production of cold antihydrogen atoms in particle traps at CERN's Antiproton Decelerator has opened up the possibility of performing direct measurements of the Earth's gravitational acceleration on purely antimatter bodies. The goal of the AEgIS collaboration is to measure the value of g for antimatter using a pulsed source of cold antihydrogen and a Moiré deflectometer/Talbot-Lau interferometer. The same antihydrogen beam is also very well suited to measuring precisely the ground-state hyperfine splitting of the anti-atom. The antihydrogen formation mechanism chosen by AEgIS is resonant charge exchange between cold antiprotons and Rydberg positronium. A series of technical developments regarding positrons and positronium (Ps formation in a dedicated room-temperature target, spectroscopy of the n=1-3 and n=3-15 transitions in Ps, Ps formation in a target at 10 K inside the 1 T magnetic field of the experiment) as well as antiprotons (high-efficiency trapping of ?, radial compression to sub-millimetre radii of mixed ? plasmas in 1 T field, high-efficiency transfer of ? to the antihydrogen production trap using an in-flight launch and recapture procedure) were successfully implemented. Two further critical steps that are germane mainly to charge exchange formation of antihydrogen-cooling of antiprotons and formation of a beam of antihydrogen-are being addressed in parallel. The coming of ELENA will allow, in the very near future, the number of trappable antiprotons to be increased by more than a factor of 50. For the antihydrogen production scheme chosen by AEgIS, this will be reflected in a corresponding increase of produced antihydrogen atoms, leading to a significant reduction of measurement times and providing a path towards high-precision measurements. This article is part of the Theo Murphy meeting issue `Antiproton physics in the ELENA era'.

What is Lethe hyrania (Kollar, 1844) (Lepidoptera, Nymphalidae, Satyrinae)?

PubMed

Lang, Song-Yun; Lamas, Gerardo

2016-02-02

Known for a long time as "Lethe insana [sic] (Kollar, 1844)" (e.g. Fruhstorfer, 1911; D'Abrera, 1985), Lethe hyrania (Kollar, 1844) is a common, sexually-dimorphic, satyrine butterfly, found in the Sino-Himalayan region. Kollar (1844) described simultaneously both Satyrus isana and S. hyrania, as separate but closely related species, from northwestern India. Kollar (1844) spelt the name of the former in two different ways, as isana in the text (pp. 448, 449, 585), and as jsana in the legend for plate 16. Westwood (1851) maintained isana and hyrania as separate species but transferred them to the genus Debis Doubleday, whereas both Butler (1868) and Kirby (1871) assigned them to the genus Lethe Hübner, synonymizing isana under L. rohria (Fabricius). Moore (1882) was the first author to regard isana and hyrania as conspecific, the former representing the female sex and the latter the male, though he misspelt isana as "isania". Acting as First Reviser, Article 24.2 of ICZN (1999), Moore (1882) gave precedence to hyrania, thus the valid name for the species is Lethe hyrania. Later, Marshall & Nicéville (1883), Nicéville (1886), Doherty (1886), Elwes (1888), and Moore (1892) followed Moore's (1882) opinion, though afterwards Mackinnon & Nicéville (1897) argued that isana had priority over hyrania, based on "page precedence", ignoring Moore's (1882) previous action. Bingham (1905) was the first author to introduce the incorrect subsequent spelling "insana" and, apparently following Mackinnon & Nicéville (1897), also gave precedence to "insana" over hyrania. Most subsequent authors followed Bingham's (1905) error, and used Lethe "insana" for this species (for instance, Fruhstorfer, 1911; Evans, 1923, 1927; Gaede, 1931; Talbot, [1949]; Lesse, 1957; D'Abrera, 1985, 1990; Bozano, 1999). Except for Bozano (1999), who listed both hyrania and "insana" as valid species, without further comment, the name hyrania has been forgotten for over a hundred years.

Mask fabrication and its applications to extreme ultra-violet diffractive optics

NASA Astrophysics Data System (ADS)

Cheng, Yang-Chun

Short-wavelength radiation around 13nm of wavelength (Extreme Ultra-Violet, EUV) is being considered for patterning microcircuits, and other electronic chips with dimensions in the nanometer range. Interferometric Lithography (IL) uses two beams of radiation to form high-resolution interference fringes, as small as half the wavelength of the radiation used. As a preliminary step toward manufacturing technology, IL can be used to study the imaging properties of materials in a wide spectral range and at nanoscale dimensions. A simple implementation of IL uses two transmission diffraction gratings to form the interference pattern. More complex interference patterns can be created by using different types of transmission gratings. In this thesis, I describe the development of a EUV lithography system that uses diffractive optical elements (DOEs), from simple gratings to holographic structures. The exposure system is setup on a EUV undulator beamline at the Synchrotron Radiation Center, in the Center for NanoTechnology clean room. The setup of the EUV exposure system is relatively simple, while the design and fabrication of the DOE "mask" is complex, and relies on advanced nanofabrication techniques. The EUV interferometric lithography provides reliable EUV exposures of line/space patterns and is ideal for the development of EUV resist technology. In this thesis I explore the fabrication of these DOE for the EUV range, and discuss the processes I have developed for the fabrication of ultra-thin membranes. In addition, I discuss EUV holographic lithography and generalized Talbot imaging techniques to extend the capability of our EUV-IL system to pattern arbitrary shapes, using more coherent sources than the undulator. In a series of experiments, we have demonstrated the use of a soft X-ray (EUV) laser as effective source for EUV lithography. EUV-IL, as implemented at CNTech, is being used by several companies and research organizations to characterize photoresist

Concentrations of Semivolatile Organic Compounds Associated with African Dust Air Masses in Mali, Cape Verde, Trinidad and Tobago, and the U.S. Virgin Islands, 2001-2008

USGS Publications Warehouse

Garrison, Virginia H.; Foreman, William T.; Genualdi, Susan A.; Majewski, Michael S.; Mohammed, Azad; Simonich, Staci Massey

2011-01-01

Every year, billions of tons of fine particles are eroded from the surface of the Sahara Desert and the Sahel of West Africa, lifted into the atmosphere by convective storms, and transported thousands of kilometers downwind. Most of the dust is carried west to the Americas and the Caribbean in the Saharan Air Layer (SAL). Dust air masses predominately impact northern South America during the Northern Hemisphere winter and the Caribbean and Southeastern United States in summer. Dust concentrations vary considerably temporally and spatially. In a dust source region (Mali), concentrations range from background levels of 575 micrograms per cubic meter (mu/u g per m3) to 13,000 mu/u g per m3 when visibility degrades to a few meters (Gillies and others, 1996). In the Caribbean, concentrations of 200 to 600 mu/u g per m3 in the mid-Atlantic and Barbados (Prospero and others, 1981; Talbot and others, 1986), 3 to 20 mu/u g per m3 in the Caribbean (Prospero and Nees, 1986; Perry and others, 1997); and >100 mu/u g per m3 in the Virgin Islands (this dataset) have been reported during African dust conditions. Mean dust particle size decreases as the SAL traverses from West Africa to the Caribbean and Americas as a result of gravitational settling. Mean particle size reaching the Caribbean is <1 micrometer (mu/u m) (Perry and others, 1997), and even finer particles are carried into Central America, the Southeastern United States, and maritime Canada. Particles less than 2.5 mu/u m diameter (termed PM2.5) can be inhaled deeply into human lungs. A large body of literature has shown that increased PM2.5 concentrations are linked to increased cardiovascular/respiratory morbidity and mortality (for example, Dockery and others, 1993; Penn and others, 2005).

Airborne Measurements of NO, NO2, and NO(y) as Related to NASA's Pacific Exploratory Mission

NASA Technical Reports Server (NTRS)

Sandholm, Scott

1997-01-01

The Tropospheric Trace Gas and Airborne Measurements Group's (TTGAMG) efforts on NASA GTE (Global Tropospheric Experiment) PEM (Pacific Exploratory Mission) West A & B field campaign primarily involved the acquisition of NO, NO2 and NO(y) measurements, as well as the subsequent analysis and interpretation of the data base obtained during the PEM West field campaign. These investigations focused on the distribution of trace gases, sources and sinks of ozone, ozone producing precursors with a heavy emphasize on ozone's photochemical state, and the partitioning of the molecules within the NO(y) family over the north western Pacific Ocean. The two components of PEM West were focused on observing air masses as they reached the Asian Continent (PEM West A) or as the air mass departed the Asian Continent (PEM West B). NO(x) concentrations play a pivotal role in controlling the photochemical lifetime of ozone in these environments, and understanding the NO(x) species partitioning is paramount. The transport of NO(x) into the regions, in the form of longer lived NO(y) family members, was examined in relation to the comparison of natural occurring sources of NO(x) (i.e., lightning and stratosphere/troposphere exchange) to those produced as a result of anthropogenic activity (i.e., biomass burning and aircraft emissions). The TTGAMG's measurements of NOx and NO(y), in conjunction with other investigators' measurements of PAN (H. B. Singh's group) and HNO3 (R. W. Talbot's group), have been used to assess the total reactive odd nitrogen levels over the study regions, the partitioning of the reactive odd nitrogen species in their various forms, and the usefulness of the NO, measurement and its measurement technique. The TTGAMG's primary PEM West objectives were the characterization of the factors controlling the distribution and fate of reactive odd nitrogen compounds over the western Pacific Ocean and an analysis of the concentration of various trace gases in the troposphere as

AEgIS at ELENA: outlook for physics with a pulsed cold antihydrogen beam.

PubMed

Doser, M; Aghion, S; Amsler, C; Bonomi, G; Brusa, R S; Caccia, M; Caravita, R; Castelli, F; Cerchiari, G; Comparat, D; Consolati, G; Demetrio, A; Di Noto, L; Evans, C; Fanì, M; Ferragut, R; Fesel, J; Fontana, A; Gerber, S; Giammarchi, M; Gligorova, A; Guatieri, F; Haider, S; Hinterberger, A; Holmestad, H; Kellerbauer, A; Khalidova, O; Krasnický, D; Lagomarsino, V; Lansonneur, P; Lebrun, P; Malbrunot, C; Mariazzi, S; Marton, J; Matveev, V; Mazzotta, Z; Müller, S R; Nebbia, G; Nedelec, P; Oberthaler, M; Pacifico, N; Pagano, D; Penasa, L; Petracek, V; Prelz, F; Prevedelli, M; Rienaecker, B; Robert, J; Røhne, O M; Rotondi, A; Sandaker, H; Santoro, R; Smestad, L; Sorrentino, F; Testera, G; Tietje, I C; Widmann, E; Yzombard, P; Zimmer, C; Zmeskal, J; Zurlo, N

2018-03-28

The efficient production of cold antihydrogen atoms in particle traps at CERN's Antiproton Decelerator has opened up the possibility of performing direct measurements of the Earth's gravitational acceleration on purely antimatter bodies. The goal of the AEgIS collaboration is to measure the value of g for antimatter using a pulsed source of cold antihydrogen and a Moiré deflectometer/Talbot-Lau interferometer. The same antihydrogen beam is also very well suited to measuring precisely the ground-state hyperfine splitting of the anti-atom. The antihydrogen formation mechanism chosen by AEgIS is resonant charge exchange between cold antiprotons and Rydberg positronium. A series of technical developments regarding positrons and positronium (Ps formation in a dedicated room-temperature target, spectroscopy of the n =1-3 and n =3-15 transitions in Ps, Ps formation in a target at 10 K inside the 1 T magnetic field of the experiment) as well as antiprotons (high-efficiency trapping of [Formula: see text], radial compression to sub-millimetre radii of mixed [Formula: see text] plasmas in 1 T field, high-efficiency transfer of [Formula: see text] to the antihydrogen production trap using an in-flight launch and recapture procedure) were successfully implemented. Two further critical steps that are germane mainly to charge exchange formation of antihydrogen-cooling of antiprotons and formation of a beam of antihydrogen-are being addressed in parallel. The coming of ELENA will allow, in the very near future, the number of trappable antiprotons to be increased by more than a factor of 50. For the antihydrogen production scheme chosen by AEgIS, this will be reflected in a corresponding increase of produced antihydrogen atoms, leading to a significant reduction of measurement times and providing a path towards high-precision measurements.This article is part of the Theo Murphy meeting issue 'Antiproton physics in the ELENA era'. © 2018 The Author(s).

Hot mill process parameters impacting on hot mill tertiary scale formation

NASA Astrophysics Data System (ADS)

Kennedy, Jonathan Ian

For high end steel applications surface quality is paramount to deliver a suitable product. A major cause of surface quality issues is from the formation of tertiary scale. The scale formation depends on numerous factors such as thermo-mechanical processing routes, chemical composition, thickness and rolls used. This thesis utilises a collection of data mining techniques to better understand the influence of Hot Mill process parameters on scale formation at Port Talbot Hot Strip Mill in South Wales. The dataset to which these data mining techniques were applied was carefully chosen to reduce process variation. There are several main factors that were considered to minimise this variability including time period, grade and gauge investigated. The following data mining techniques were chosen to investigate this dataset: Partial Least Squares (PLS); Logit Analysis; Principle Component Analysis (PCA); Multinomial Logistical Regression (MLR); Adaptive Neuro Inference Fuzzy Systems (ANFIS). The analysis indicated that the most significant variable for scale formation is the temperature entering the finishing mill. If the temperature is controlled on entering the finishing mill scale will not be formed. Values greater than 1070 °C for the average Roughing Mill and above 1050 °C for the average Crop Shear temperature are considered high, with values greater than this increasing the chance of scale formation. As the temperature increases more scale suppression measures are required to limit scale formation, with high temperatures more likely to generate a greater amount of scale even with fully functional scale suppression systems in place. Chemistry is also a significant factor in scale formation, with Phosphorus being the most significant of the chemistry variables. It is recommended that the chemistry specification for Phosphorus be limited to a maximum value of 0.015 % rather than 0.020 % to limit scale formation. Slabs with higher values should be treated with

Mass and number size distributions of particulate matter components: comparison of an industrial site and an urban background site.

PubMed

Taiwo, Adewale M; Beddows, David C S; Shi, Zongbo; Harrison, Roy M

2014-03-15

Size-resolved composition of particulate matter (PM) sampled in the industrial town of Port Talbot (PT), UK was determined in comparison to a typical urban background site in Birmingham (EROS). A Micro-Orifice Uniform Deposit Impactor (MOUDI) sampler was deployed for two separate sampling campaigns with the addition of a Grimm optical spectrometer at the PT site. MOUDI samples were analysed for water-soluble anions (Cl(-), NO₃(-) and SO₄(2-)) and cations (Na(+), NH4(+), K(+), Mg(2+) and Ca(2+)) and trace metals (Al, V, Cr, Mn, Fe, Cu, Zn, Sb, Ba and Pb). The PM mass distribution showed a predominance of fine particle (PM₂.₅) mass at EROS whereas the PT samples were dominated by the coarse fraction (PM₂.₅₋₁₀). SO₄(2-), Cl(-), NH4(+), Na(+), NO₃(-), and Ca(2+) were the predominant ionic species at both sites while Al and Fe were the metals with highest concentrations at both sites. Mean concentrations of Cl(-), Na(+), K(+), Ca(2+), Mg(2+), Cr, Mn, Fe and Zn were higher at PT than EROS due to industrial and marine influences. The contribution of regional pollution by sulphate, ammonium and nitrate was greater at EROS relative to PT. The traffic signatures of Cu, Sb, Ba and Pb were particularly prominent at EROS. Overall, PM at EROS was dominated by secondary aerosol and traffic-related particles while PT was heavily influenced by industrial activities and marine aerosol. Profound influences of wind direction are seen in the 72-hour data, especially in relation to the PT local sources. Measurements of particle number in 14 separate size bins plotted as a function of wind direction and speed are highly indicative of contributing sources, with local traffic dominant below 0.5 μm, steelworks emissions from 0.5 to 15 μm, and marine aerosol above 15 μm. Copyright © 2013 Elsevier B.V. All rights reserved.

Cognitive Behavioral Therapy for Insomnia in Posttraumatic Stress Disorder: A Randomized Controlled Trial

PubMed Central

Talbot, Lisa S.; Maguen, Shira; Metzler, Thomas J.; Schmitz, Martha; McCaslin, Shannon E.; Richards, Anne; Perlis, Michael L.; Posner, Donn A.; Weiss, Brandon; Ruoff, Leslie; Varbel, Jonathan; Neylan, Thomas C.

2014-01-01

disorder should include behavioral sleep medicine. Clinical Trial Information: Trial Name: Cognitive Behavioral Treatment Of Insomnia In Posttraumatic Stress Disorder. URL: http://clinicaltrials.gov/ct2/show/NCT00881647. Registration Number: NCT00881647. Citation: Talbot LS; Maguen S; Metzler TJ; Schmitz M; McCaslin SE; Richards A; Perlis ML; Posner DA; Weiss B; Ruoff L; Varbel J; Neylan TC. Cognitive behavioral therapy for insomnia in posttraumatic stress disorder: a randomized controlled trial. SLEEP 2014;37(2):327-341. PMID:24497661

Polarized Light Microscopy

NASA Technical Reports Server (NTRS)

Frandsen, Athela F.

2016-01-01

Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often

Water isotope systematics: Improving our palaeoclimate interpretations

USGS Publications Warehouse

Jones, M. D.; Dee, S.; Anderson, L.; Baker, A.; Bowen, G.; Noone, D.

2016-01-01

The stable isotopes of oxygen and hydrogen, measured in a variety of archives, are widely used proxies in Quaternary Science. Understanding the processes that control δ18O change have long been a focus of research (e.g. Shackleton and Opdyke, 1973; Talbot, 1990 ; Leng, 2006). Both the dynamics of water isotope cycling and the appropriate interpretation of geological water-isotope proxy time series remain subjects of active research and debate. It is clear that achieving a complete understanding of the isotope systematics for any given archive type, and ideally each individual archive, is vital if these palaeo-data are to be used to their full potential, including comparison with climate model experiments of the past. Combining information from modern monitoring and process studies, climate models, and proxy data is crucial for improving our statistical constraints on reconstructions of past climate variability.As climate models increasingly incorporate stable water isotope physics, this common language should aid quantitative comparisons between proxy data and climate model output. Water-isotope palaeoclimate data provide crucial metrics for validating GCMs, whereas GCMs provide a tool for exploring the climate variability dominating signals in the proxy data. Several of the studies in this set of papers highlight how collaborations between palaeoclimate experimentalists and modelers may serve to expand the usefulness of palaeoclimate data for climate prediction in future work.This collection of papers follows the session on Water Isotope Systematics held at the 2013 AGU Fall Meeting in San Francisco. Papers in that session, the breadth of which are represented here, discussed such issues as; understanding sub-GNIP scale (Global Network for Isotopes in Precipitation, (IAEA/WMO, 2006)) variability in isotopes in precipitation from different regions, detailed examination of the transfer of isotope signals from precipitation to geological archives, and the

Abortion foes get turn to ask Supreme Court for constitutional protection.

PubMed

Denniston, L

1994-04-28

judge's order. Clinic lawyer, Talbot D'Alemberte, president of Florida State University and former president of the American Bar Association, will argue that the issue is about intimidation. The Clinton administration's Solicitor General Drew S. Days III will support Seminole County Circuit Court Judge Robert S. McGregor's decision limiting protester activity.

Quantum light in novel systems

NASA Astrophysics Data System (ADS)

Rai, Amit

2011-12-01

In this thesis we have focused on the study of various systems which are presently widely studied in different areas of quantum optics and quantum information sciences. These, for example, include the coupled system of photonic waveguides which are known to be highly efficient in manipulating the flow of light. The Hamiltonian describing the evolution of field mode in coupled waveguides is effectively identical to the well-known tight binding Hamiltonian used in solid state physics. The advantage of waveguide system is the possibility to control various interactions by design and their low decoherence rate. The excellent stability offered by coupled waveguides has led to the observation of many key coherent effects such as quantum walk, Bloch oscillation, and discrete Talbot effect. For example, Bloch oscillations have been investigated in coupled waveguides using coherent beam of light. We wanted to inquire whether coherent phenomena such as Bloch oscillations can be possible with incoherent single photon sources. We discovered that Bloch oscillations are indeed possible with single photons provided we prepare single photons in a W state. Moreover, coupled waveguides also find applications in the field of quantum information processing. Since entanglement plays a prominent role in all these applications, it is important to understand the entanglement dynamics in these structures. We considered the case of squeezed input in one of the waveguide and showed that one can generate entanglement between the waveguide modes. We further continued our work on the entanglement generation in coupled waveguides by incorporating the effect of loss in the waveguide structure for the squeezed and photon number input states. We considered relevant experimental parameters and showed that waveguide structures are reasonably robust against the effect of loss. Another system which has attracted a great deal of interest is the optomechanical system. We consider an optomechanical system

Unraveling the hydrocarbon charge potential of the Nordkapp Basin, Barents Sea: An integrated approach to reduce exploration risk in complex salt basins

NASA Astrophysics Data System (ADS)

Schenk, Oliver; Shtukert, Olga; Bishop, Andrew; Kornpihl, Kristijan; Milne, Graham

2014-05-01

Pleistocene (glacial). The models have been thermally calibrated. Consideration of Pleistocene glacial/interglacial cycles was required for thermal calibration as well as to better understand and predict the hydrocarbon phase behavior. References: Koyi, H., Talbot, C.J., Tørudbakken, B.O., 1993, Salt diapirs of the southwest Nordkapp Basin: analogue modelling, Tectonophysics, Volume 228, Issues 3-4, Pages 167-187. Nilsen, K.T., Vendeville, B.C., Johansen, J.-T., 1995, Influence of regional tectonics on halokinesis in the Nordkapp Basin, Barents Sea. In: Jackson, M.P.A., Roberts, D.G., Snelson, S. (eds), Salt tectonics, a global perspective, AAPG Memoir 65, 413-436.

Grating-based phase contrast tomosynthesis imaging: Proof-of-concept experimental studies

PubMed Central

Li, Ke; Ge, Yongshuai; Garrett, John; Bevins, Nicholas; Zambelli, Joseph; Chen, Guang-Hong

2014-01-01

Purpose: This paper concerns the feasibility of x-ray differential phase contrast (DPC) tomosynthesis imaging using a grating-based DPC benchtop experimental system, which is equipped with a commercial digital flat-panel detector and a medical-grade rotating-anode x-ray tube. An extensive system characterization was performed to quantify its imaging performance. Methods: The major components of the benchtop system include a diagnostic x-ray tube with a 1.0 mm nominal focal spot size, a flat-panel detector with 96 μm pixel pitch, a sample stage that rotates within a limited angular span of ±30°, and a Talbot-Lau interferometer with three x-ray gratings. A total of 21 projection views acquired with 3° increments were used to reconstruct three sets of tomosynthetic image volumes, including the conventional absorption contrast tomosynthesis image volume (AC-tomo) reconstructed using the filtered-backprojection (FBP) algorithm with the ramp kernel, the phase contrast tomosynthesis image volume (PC-tomo) reconstructed using FBP with a Hilbert kernel, and the differential phase contrast tomosynthesis image volume (DPC-tomo) reconstructed using the shift-and-add algorithm. Three inhouse physical phantoms containing tissue-surrogate materials were used to characterize the signal linearity, the signal difference-to-noise ratio (SDNR), the three-dimensional noise power spectrum (3D NPS), and the through-plane artifact spread function (ASF). Results: While DPC-tomo highlights edges and interfaces in the image object, PC-tomo removes the differential nature of the DPC projection data and its pixel values are linearly related to the decrement of the real part of the x-ray refractive index. The SDNR values of polyoxymethylene in water and polystyrene in oil are 1.5 and 1.0, respectively, in AC-tomo, and the values were improved to 3.0 and 2.0, respectively, in PC-tomo. PC-tomo and AC-tomo demonstrate equivalent ASF, but their noise characteristics quantified by the 3D NPS

You Don't Need Richards'... A New General 1-D Vadose Zone Solution Method that is Reliable

NASA Astrophysics Data System (ADS)

Ogden, F. L.; Lai, W.; Zhu, J.; Steinke, R. C.; Talbot, C. A.

2015-12-01

Hydrologic modelers and mathematicians have strived to improve 1-D Richards' equation (RE) solution reliability for predicting vadose zone fluxes. Despite advances in computing power and the numerical solution of partial differential equations since Richards first published the RE in 1931, the solution remains unreliable. That is to say that there is no guarantee that for a particular set of soil constitutive relations, moisture profile conditions, or forcing input that a numerical RE solver will converge to an answer. This risk of non-convergence renders prohibitive the use of RE solvers in hydrological models that need perhaps millions of infiltration solutions. In lieu of using unreliable numerical RE solutions, researchers have developed a wide array of approximate solutions that more-or-less mimic the behavior of the RE, with some notable deficiencies such as parameter insensitivity or divergence over time. The improved Talbot-Ogden (T-O) finite water-content scheme was shown by Ogden et al. (2015) to be an extremely good approximation of the 1-D RE solution, with a difference in cumulative infiltration of only 0.2 percent over an 8 month simulation comparing the improved T-O scheme with a RE numerical solver. The reason is that the newly-derived fundamental flow equation that underpins the improved T-O method is equivalent to the RE minus a term that is equal to the diffusive flux divided by the slope of the wetting front. Because the diffusive flux has zero mean, this term is not important in calculating the mean flux. The wetting front slope is near infinite (sharp) in coarser soils that produce more significant hydrological interactions between surface and ground waters, which also makes this missing term 1) disappear in the limit, and, 2) create stability challenges for the numerical solution of RE. The improved T-O method is a replacement for the 1-D RE in soils that can be simulated as homogeneous layers, where the user is willing to neglect the effects

Hydraulic and thermal soil Parameter combined with TEM data at quaternary coastal regions

NASA Astrophysics Data System (ADS)

Grabowski, Ima; Kirsch, Reinhard; Scheer, Wolfgang

2014-05-01

In order to generate a more efficient method of planning and dimensioning small- and medium sized geothermal power plants at quaternary subsurface a basic approach has been attempted. Within the EU-project CLIWAT, the coastal region of Denmark, Germany, Netherlands and Belgium has been investigated and air borne electro magnetic data was collected. In this work the regional focus was put on the isle of Föhr. To describe the subsurface with relevant parameters one need the information from drillings and geophysical well logging data. The approach to minimize costs and use existing data from state agencies led the investigation to the combination of specific electrical resistivity data and hydraulic and thermal conductivity. We worked out a basic soil/hydraulic conductivity statistic for the isle of Föhr by gathering all well logging data from the island and sorted the existing soil materials to associated kf -values. We combined specific electrical resistivity with hydraulic soil properties to generate thermal conductivity values by extracting porosity. Until now we generated a set of rough data for kf - values and thermal conductivity. The air borne TEM data sets are reliable up to 150 m below surface, depending on the conductivity of the layers. So we can suppose the same for the differentiated parameters. Since this is a very rough statistic of kf -values, further more investigation has to be made. Although the close connection to each area of investigation either over existing logging data or laboratory soil property values will remain necessary. Literature: Ahmed S, de Marsily G, Talbot A (1988): Combined Use of Hydraulic and Electrical Properties of an Aquifer in a Geostatistical Estimation of Transmissivity. - Groundwater, vol. 26 (1) Burschil T, Scheer W, Wiederhold H, Kirsch R (2012): Groundwater situation on a glacially affected barrier island. Submitted to Hydrology and Earth System Sciences - an Interactive Open Access Journal of the European

N Isotopes in Nile Sediments (ethiopia, Sudan)

NASA Astrophysics Data System (ADS)

Padoan, M.; Villa, I. M.; Garzanti, E.; Galbusera, M.; Quistini, S.; Peruta, L.; El Kammar, A.

2009-04-01

The Nile is the most important river of the Eastern Mediterranean. Its water and sediment fluxes have greatly influenced marine circulation throughout the Quaternary, and are widely considered as possible causes for stagnation and formation of sapropel (Krom et al., 1999a; 2002; Talbot et al., 2000; Freydier et al., 2001; Weldeab et al., 2002; Scrivner et al., 2004). Variations in annual flooding and baseflow of the river Nile, controlled by climate changes, had major impact on the rise and demise of Egyptian dynasties (Stanley et al., 2003). In order to better define sedimentary sources of the Nile system and to obtain more robust results, we have analyzed Nd isotopes in sediments of all its major Sudanese and Ethiopian tributaries (Atbara, Gash, Abay, Didesa, Dabus, White Nile, Bahr Ez Zeraf) in several replicate samples. Analyses were carried out on distinct mud and sand fractions (<40 microns and 125-180 microns) of 30 samples, and systematic changes related to grain size and hydraulic-sorting processes could thus be investigated. On the same samples, companion studies are being carried out on Sr isotopes (Padoan et al., 2007) and on Pb isotopes at the Geological Survey of Israel (Harlavan et al., in preparation). Overall, isotopic signals are markedly different between the White Nile system, derived from largely Archean to Paleoproterozoic basement rocks, and Ethiopian tributaries, derived in diverse proportions from largely Neoproterozoic rift-shoulder basements and overlying Oligocene flood basalts. Isotopic signals of Main Nile sediments downstream of the Atbara confluence are close to those of Blue Nile sediments, indicating that detritus is mainly provided by the latter (Garzanti et al., 2006). In the White Nile branch, the 143Nd/144Nd ratio of the mud fraction is lower in the Bahr Ez Zeraf (0.51167) than in the White Nile downstrean of the Sobat confluence (0.51219), revealing significant sediment influx from the latter. In Blue Nile and Atbara branches

Geochemical and biological influences on the distribution of bacteriohopanepolyol biomarkers in hydrothermal springs

NASA Astrophysics Data System (ADS)

Boyer, G. M.; Woods, J.; Schubotz, F.; Shock, E.; Boyd, E. S.; Summons, R. E.

2013-12-01

as more nitrogen becomes available, bacteria incorporate it into a greater proportion of their BHPs. However, this relationship appears to be highly influenced by pH, with acidic sites having a greater percentage of nitrogen-bearing BHPs than near-neutral or alkaline sites. Finally, the number of BHP structures detected is positively correlated with the diversity of bacterial 16S rDNA genes (R2 = 0.62, logarithmic fit), suggesting that BHP structural diversity is a good proxy for estimating bacterial taxonomic diversity. [1] H. M. Talbot et al., Org. Geochem. 39, 232-263 (2008). [2] S. D'Imperio et al., Appl. Environ. Microbiol. 74, 5802-5808 (2008). [3] R. W. Castenholz, Microb. Ecol. 3, 79-105 (1977). [4] E. S. Boyd et al., Front. Microbiol. 3: 221 (2012).

Quantitative X-ray Differential Interference Contrast Microscopy

NASA Astrophysics Data System (ADS)

Nakamura, Takashi

Full-field soft x-ray microscopes are widely used in many fields of sciences. Advances in nanofabrication technology enabled short wavelength focusing elements with significantly improved spatial resolution. In the soft x-ray spectral region, samples as small as 12 nm can be resolved using micro zone-plates as the objective lens. In addition to conventional x-ray microscopy in which x-ray absorption difference provides the image contrast, phase contrast mechanisms such as differential phase contrast (DIC) and Zernike phase contrast have also been demonstrated These phase contrast imaging mechanisms are especially attractive at the x-ray wavelengths where phase contrast of most materials is typically 10 times stronger than the absorption contrast. With recent progresses in plasma-based x- ray sources and increasing accessibility to synchrotron user facilities, x-ray microscopes are quickly becoming standard measurement equipment in the laboratory. To further the usefulness of x-ray DIC microscopy this thesis explicitly addresses three known issues with this imaging modality by introducing new techniques and devices First, as opposed to its visible-light counterpart, no quantitative phase imaging technique exists for x-ray DIC microscopy. To address this issue, two nanoscale x-ray quantitative phase imaging techniques, using exclusive OR (XOR) patterns and zone-plate doublets, respectively, are proposed. Unlike existing x-ray quantitative phase imaging techniques such as Talbot interferometry and ptychography, no dedicated experimental setups or stringent illumination coherence are needed for quantitative phase retrieval. Second, to the best of our knowledge, no quantitative performance characterization of DIC microscopy exists to date. Therefore the imaging system's response to sample's spatial frequency is not known In order to gain in-depth understanding of this imaging modality, performance of x-ray DIC microscopy is quantified using modulation transfer function

The O and H stable isotope composition of freshwaters in the British Isles. 2. Surface waters and groundwater

NASA Astrophysics Data System (ADS)

Darling, W. G.; Bath, A. H.; Talbot, J. C.

The utility of stable isotopes as tracers of the water molecule has a long pedigree. The study reported here is part of an attempt to establish a comprehensive isotopic "baseline" for the British Isles as background data for a range of applications. Part 1 of this study (Darling and Talbot, 2003) considered the isotopic composition of rainfall in Britain and Ireland. The present paper is concerned with the composition of surface waters and groundwater. In isotopic terms, surface waters (other than some upland streams) are poorly characterised in the British Isles; their potential variability has yet to be widely used as an aid in hydrological research. In what may be the first study of a major British river, a monthly isotopic record of the upper River Thames during 1998 was obtained. This shows high damping of the isotopic variation compared to that in rainfall over most of the year, though significant fluctuations were seen for the autumn months. Smaller rivers such as the Stour and Darent show a more subdued response to the balance between runoff and baseflow. The relationship between the isotopic composition of rainfall and groundwater is also considered. From a limited database, it appears that whereas Chalk groundwater is a representative mixture of weighted average annual rainfall, for Triassic sandstone groundwater there is a seasonal selection of rainfall biased towards isotopically-depleted winter recharge. This may be primarily the result of physical differences between the infiltration characteristics of rock types, though other factors (vegetation, glacial history) could be involved. In the main, however, groundwaters appear to be representative of bulk rainfall within an error band of 0.5‰ δ18O. Contour maps of the δ18O and δ2H content of recent groundwaters in the British Isles show a fundamental SW-NE depletion effect modified by topography. The range of measured values, while much smaller than those for rainfall, still covers some ‰ for δ18

Aspects of the internal kinematics and dynamics of salt diapirs: Results from thermomechanical experiments

NASA Astrophysics Data System (ADS)

Zulauf, G.; Zulauf, J.; Peinl, M.; Kihm, N.; Zanella, F.; Bornemann, O.

2009-04-01

The internal parts of salt diapirs are characterized by constrictional deformation supporting steeply plunging prolate fabrics and related linear (L>S) fabrics (Talbot and Jackson 1987). The youngest folds recognized in stems of salt diapirs are known from German Zechstein salt as curtain folds (Kulissen- or Vorhangfalten, Hartwig 1925) because the steeply inclined bedding planes define steeply plunging cylindrical folds. The grain-shape lineation tends to parallel the hinge lines of curtain folds. In cases of rheological stratification (e.g. stiff anhydrite or shale layers embedded in a weaker halite matrix), the curtain folds should be associated with boudins, the latter resulting from vertical extension parallel to the steep axes of the curtain folds. A new deformation apparatus has been used to model the internal kinematics of rheologically stratified salt diapirs. Composite natural samples consisting of a single layer of Gorleben anhydrite, embedded in matrix of Asse halite (both from Zechstein formation of northern Germany), were constrictionally deformed at temperature, T = 345˚ C, strain rate, Ä- = 10-7 s-1, maximum viscosity, η = 2 x 1013 Pa s, and maximum finite strain, eX = 122%. Viscous flow of Asse halite under the conditions listed above was accommodated by dislocation creep, which can be approximated by the equation obtained experimentally by Carter et al. (1993) for low stresses. Dislocation creep was related to formation of subgrains which are forming a striking chessboard pattern in sections cut parallel to the major stretching axis, X. The subgrain size, D, has been used to estimate the differential stress, , using the equation obtained by Schléder and Urai (2005) after combining the calibrations published by Carter et al. (1993) and Franssen (1993). The piezometrically derived stress values are between 2 and 6 MPa. Although the prerequisites for piezometry are not fully met in the present case of Asse halite (e.g. steady

The Welsh Blood Service - 70 years of continuous change.

PubMed

Poole, G D

2017-06-01

The National Blood Transfusion Service (NBTS) in England and Wales was established as a single entity in 1946 and operated as such for almost half a century. During those 50 years, the blood service in Wales, as in the rest of the UK, saw many technological and operational changes. The automation of donation testing, the introduction of successive layers of microbiological screening, the creation of the Tissue Typing Laboratory (later renamed the Welsh Transplantation and Immunogenetics Laboratory) and the development of information technology brought - over a relatively long period - highly significant improvements to an organisation that had begun life as an Emergency Medical Service. Differing funding and reporting arrangements for the Welsh and English blood services made little difference in practice, but the devolution of government following the 1997 referendum in Wales would have a profound influence. Four years before the Government of Wales Act (1998) was passed through the UK parliament, the National Blood Authority (NBA) assumed executive control of the English blood services but not the blood service in Wales. The Scottish National Blood Transfusion Service and the Northern Ireland Blood Transfusion Service had been created as independent organisations in 1946; thus, the scene was set for diversification between the four independent blood services, each operating in different political environments with different funding streams. The creation of the UK Blood Services Forum and its Joint Professional Advisory Committee in 1999 has, however, ensured consistency in professional matters. The blood transfusion service in Wales, in its new headquarters in Talbot Green, became known as the Welsh Blood Service (WBS), or Gwasanaeth Gwaed Cymru in Welsh, reporting for most of its life to the Velindre NHS Trust, part of NHS Wales. Considerable changes would impact the WBS in the 21st century. Social changes would mean that the role of recruitment and marketing

A short history of pediatric endocrinology in North America.

PubMed

Fisher, Delbert A

2004-04-01

Pediatric endocrinology evolved as a subspecialty from the era of biochemical and metabolic clinical investigation led by John Howland, Edwards Park, and James Gamble at Johns Hopkins; Allan Butler at Boston University and Harvard University; Daniel Darrow at Yale University; and Irving McQuarrie at the University of Rochester and the University of Minnesota during the early 20th century. The father of the new subspecialty was Lawson Wilkins, a private pediatric practitioner in Baltimore, Maryland, who was invited by Dr. Edwards Park to establish an endocrine clinic at the Harriet Lane Home at Johns Hopkins in 1935. Dr. Wilkins managed his practice and the clinic until 1946, when, at the age of 52, he accepted a full-time position at the University. Dr. Nathan Talbot was invited to develop a pediatric endocrine clinic at Massachusetts General Hospital by Allan Butler in 1942. These units and their associated subspecialty training programs during the 1950s and 1960s provided the large majority of the second-generation pediatric endocrinologists who went on to establish endocrine subspecialty programs in university medical centers in North America as well as Europe and South America. Diabetes as a clinical pediatric discipline evolved in parallel from the early clinics of Elliott Joslin and Priscilla White in Boston, M.C. Hardin and Robert Jackson at the University of Iowa, George Guest at the University of Cincinnati Children's Hospital, and Alex Hartman at the St. Louis Children's Hospital. The Lawson Wilkins Pediatric Endocrine Society was founded in 1971, and the Council on Diabetes and Youth was established within the American Diabetes Association in 1980. Medical and economic factors led to increasing integration of pediatric diabetes and general endocrine care and training, and diabetes care now is a major activity within the subspecialty of pediatric endocrinology. The growth of pediatric endocrinology in North America has paralleled the growth of academic

Tracking Soil Organic Carbon Transport to Continental Margin Sediments Using Soil-Specific Hopanoid Biomarkers: a Case Study From the Congo Fan (ODP Site 1075)

NASA Astrophysics Data System (ADS)

Cooke, M. P.; Talbot, H. M.; Eniola, O.; Zabel, M.; Wagner, T.

2007-12-01

markers in each sample analyzed down to 89 m depth in addition to the presence of common sediment associated BHPs. Concentrations of soil markers are high in the upper sediment section down to about 49 m supporting the case for these molecular markers as novel proxies for SOC supply and burial. Distinct peaks of adenosyl and 2 methyl adenosyl hopane at about 200, 300 and 550 kyrs tentatively imply that the rate of terrestrial organic matter discharge from tropical Africa significantly increased at these times, possibly associated with periods of reduced soil stability in the Congo catchment. Analysis of the surface sediments from 4 other cores in close proximity to ODP site 1075 clearly shows that the percentage contribution of soil marker BHPs decreases with increasing distance from the river mouth, indicating that the river is the source of these BHPs. References 1. Rohmer, M. 1993. Pure and Applied Chemistry 65, 1293-1298. 2. Talbot, H.M., Rohmer, M., Farrimond, P., 2007. Rapid Communications in Mass Spectrometry (In press). 3. Holtvoeth, J., Wagner, T., Kolonic, S., 2005. Geochimica et Cosmochimica Acta, 69, 2031-2041.

Characterization of imaging performance in differential phase contrast CT compared with the conventional CT: Spectrum of noise equivalent quanta NEQ(k)

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

Tang Xiangyang; Yang Yi; Tang Shaojie

Purpose: Differential phase contrast CT (DPC-CT) is emerging as a new technology to improve the contrast sensitivity of conventional attenuation-based CT. The noise equivalent quanta as a function over spatial frequency, i.e., the spectrum of noise equivalent quanta NEQ(k), is a decisive indicator of the signal and noise transfer properties of an imaging system. In this work, we derive the functional form of NEQ(k) in DPC-CT. Via system modeling, analysis, and computer simulation, we evaluate and verify the derived NEQ(k) and compare it with that of the conventional attenuation-based CT. Methods: The DPC-CT is implemented with x-ray tube and gratings.more » The x-ray propagation and data acquisition are modeled and simulated through Fresnel and Fourier analysis. A monochromatic x-ray source (30 keV) is assumed to exclude any system imperfection and interference caused by scatter and beam hardening, while a 360 Degree-Sign full scan is carried out in data acquisition to avoid any weighting scheme that may disrupt noise randomness. Adequate upsampling is implemented to simulate the x-ray beam's propagation through the gratings G{sub 1} and G{sub 2} with periods 8 and 4 {mu}m, respectively, while the intergrating distance is 193.6 mm (1/16 of the Talbot distance). The dimensions of the detector cell for data acquisition are 32 Multiplication-Sign 32, 64 Multiplication-Sign 64, 96 Multiplication-Sign 96, and 128 Multiplication-Sign 128 {mu}m{sup 2}, respectively, corresponding to a 40.96 Multiplication-Sign 40.96 mm{sup 2} field of view in data acquisition. An air phantom is employed to obtain the noise power spectrum NPS(k), spectrum of noise equivalent quanta NEQ(k), and detective quantum efficiency DQE(k). A cylindrical water phantom at 5.1 mm diameter and complex refraction coefficient n= 1 -{delta}+i{beta}= 1 -2.5604 Multiplication-Sign 10{sup -7}+i1.2353 Multiplication-Sign 10{sup -10} is placed in air to measure the edge transfer function, line spread function

Fabrication et applications des reseaux de Bragg ultra-longs

NASA Astrophysics Data System (ADS)

Gagne, Mathieu

This thesis presents the principal accomplishments realized during the PhD project. The thesis is presented by publication format and is a collection of four published articles having fiber Bragg gratings as a central theme. First achieved in 1978, UV writing of fiber Bragg gratings is nowadays a common and mature technology being present in both industry and academia. The property of reflecting light guided by optical fibers lead to diverse applications in telecommunication, lasers as well as several types of sensors. The conventional fabrication technique is generally based on the use of generally expensive phase masks which determine the obtained characteristics of the fiber Bragg grating. The fiber being photosensitive at those wavelengths, a periodic pattern can be written into it. The maximal length, the period, the chirp, the index contrast and the apodisation are all characteristics that depend on the phase mask. The first objective of the research project is to be able to go beyond this strong dependance on the phase mask without deteriorating grating quality. This is what really sets apart the technique presented in this thesis from other long fiber Bragg grating fabrication techniques available in the literature. The fundamental approach to obtain ultra long fiber Bragg gratings of arbitrary profile is to replace the scheme of scanning a UV beam across a phase mask to expose a fixed fiber by a scheme where the UV beam and phase mask are fixed and where the fiber is moving instead. To obtain a periodic index variation, the interference pattern itself must be synchronized with the moving fiber. Two variations of this scheme were implanted: the first one using electro-optical phase modulator placed in each arm of a Talbot interferometer and the second one using a phase mask mounted on a piezo electric actuator. A new scheme that imparts fine movements of the interferometer is also implemented for the first time and showed to be essential to achieve high

Flexible fabrication of multi-scale integrated 3D periodic nanostructures with phase mask

NASA Astrophysics Data System (ADS)

Yuan, Liang Leon

Top-down fabrication of artificial nanostructures, especially three-dimensional (3D) periodic nanostructures, that forms uniform and defect-free structures over large area with the advantages of high throughput and rapid processing and in a manner that can further monolithically integrate into multi-scale and multi-functional devices is long-desired but remains a considerable challenge. This thesis study advances diffractive optical element (DOE) based 3D laser holographic nanofabrication of 3D periodic nanostructures and develops new kinds of DOEs for advanced diffracted-beam control during the fabrication. Phase masks, as one particular kind of DOE, are a promising direction for simple and rapid fabrication of 3D periodic nanostructures by means of Fresnel diffraction interference lithography. When incident with a coherent beam of light, a suitable phase mask (e.g. with 2D nano-grating) can create multiple diffraction orders that are inherently phase-locked and overlap to form a 3D light interference pattern in the proximity of the DOE. This light pattern is typically recorded in photosensitive materials including photoresist to develop into 3D photonic crystal nanostructure templates. Two kinds of advanced phase masks were developed that enable delicate phase control of multiple diffraction beams. The first exploits femtosecond laser direct writing inside fused silica to assemble multiple (up to nine) orthogonally crossed (2D) grating layers, spaced on Talbot planes to overcome the inherent weak diffraction efficiency otherwise found in low-contrast volume gratings. A systematic offsetting of orthogonal grating layers to establish phase offsets over 0 to pi/2 range provided precise means for controlling the 3D photonic crystal structure symmetry between body centered tetragonal (BCT) and woodpile-like tetragonal (wTTR). The second phase mask consisted of two-layered nanogratings with small sub-wavelength grating periods and phase offset control. That was

Modelling Holocene peatland and permafrost dynamics with the LPJ-GUESS dynamic vegetation model

NASA Astrophysics Data System (ADS)

Chaudhary, Nitin; Miller, Paul A.; Smith, Benjamin

2016-04-01

-1361. - Frolking S, Roulet NT, Tuittila E, Bubier JL, Quillet A, Talbot J, Richard PJH. 2010. A new model of Holocene peatland net primary production, decomposition, water balance, and peat accumulation. Earth Syst. Dynam., 1, 1-21, doi:10.5194/esd-1-1-2010, 2010. - Hilbert DW, Roulet N, Moore T. 2000. Modelling and analysis of peatlands as dynamical systems. Journal of Ecology 88: 230-242. - Kleinen T, Brovkin V, Schuldt RJ. 2012. A dynamic model of wetland extent and peat accumulation: results for the Holocene. Biogeosciences 9: 235-248. - Kokfelt U, Reuss N, Struyf E, Sonesson M, Rundgren M, Skog G, Rosen P, Hammarlund D. 2010. Wetland development, permafrost history and nutrient cycling inferred from late Holocene peat and lake sediment records in subarctic Sweden. Journal of Paleolimnology 44: 327-342. - Loisel J, et al. 2014. A database and synthesis of northern peatland soil properties and Holocene carbon and nitrogen accumulation. Holocene 24: 1028-1042. - Sitch S, et al. 2008. Evaluation of the terrestrial carbon cycle, future plant geography and climate-carbon cycle feedbacks using five Dynamic Global Vegetation Models (DGVMs). Global Change Biology 14: 2015-2039. - Smith B, Prentice IC, Sykes MT. 2001. Representation of vegetation dynamics in the modelling of terrestrial ecosystems: comparing two contrasting approaches within European climate space. Global Ecology and Biogeography 10: 621-637. - Tang J, et al. 2015. Carbon budget estimation of a subarctic catchment using a dynamic ecosystem model at high spatial resolution. Biogeosciences 12: 2791-2808. - Wania R, Ross I, Prentice IC. 2009a. Integrating peatlands and permafrost into a dynamic global vegetation model: 1. Evaluation and sensitivity of physical land surface processes. Global Biogeochemical Cycles 23.

High Arctic paleoenvironmental and Paleoclimatic changes in the Mid-Cretaceous

NASA Astrophysics Data System (ADS)

Herrle, Jens; Schröder-Adams, Claudia; Selby, David; Du Vivier, Alice; Flögel, Sascha; McAnena, Alison; Davis, William; Pugh, Adam; Galloway, Jennifer; Hofmann, Peter; Wagner, Thomas

2014-05-01

the OAE2 period which shades a new light on temperature gradients during different climate states of the Cretaceous. In contrast, to the Late Cenomanian to Early Turonian the distinct occurrence of several widespread glendonite beds in the Late Aptian to Early Albian support cool bottom waters of about 0°C in the Arctic Sverdrup Basin, consistent with much lower TEX86-SST ~28°C, McAnena et al., 2013) and bottom water temperatures (6°C, Huber et al., 2011) in the low latitude North Atlantic. This supports the global character of the proposed Late Aptian cold snap (Kemper, 1987; Herrle & Mutterlose, 2003; Mutterlose et al. 2009; McAnena et al. 2013) and perhaps a northern hemisphere high-latitude intermediate bottom water source. References Du Vivier, A.C.D., Selby, D., Sageman, B.B., Jarvis, I., Gröcke, D.R., Voigt, S., 2014. Marine 187Os/188Os isotope stratigraphy reveals the interaction of volcanism and ocean circulation during Oceanic Anoxic Event 2. EPSL 389, 23-33. Föllmi, K.B., 2012. Early Cretaceous life, climate and anoxia. Cretaceous Research 35, 230-257. Hay, W.W., 2008. Evolving ideas about the Cretaceous climate and ocean circulation. Cretaceous Research 29, 725-753. Hay, W.W., 2011. Can humans force a return to a "Cretaceous" climate? Sedimentary Geology 235, 5-26. Herrle, J.O. , Mutterlose, J., 2003. Calcareous nannofossils from the Aptian - early Albian of SE France: Paleoecological and biostratigraphic implications. Cretaceous Research 24, 1-22. Huber, B.T., MacLeod, K.G., Gröcke, D.R., Kucera, M., 2011. Paleotemperature and paleosalinity inferences and chemostratigraphy across the Aptian/Albian boundary in the subtropical North Atlantic. Paleoceanography 26, PA4221 doi:10.1029/2011PA002178. McAnena, A., Flögel, S., Hofmann, P., Herrle, J.O., Griesand, A., Pross, J., Talbot, H.M., Rethemeyer, J., Wallmann, K., Wagner, T., 2013. Atlantic cooling associated with a marine biotic crisis during the mid-Cretaceous period. Nature Geoscience 6, 558

PREFACE: A Stellar Journey A Stellar Journey

NASA Astrophysics Data System (ADS)

Asplund, M.

2008-10-01

appreciated non-astronomical session on Tuesday afternoon; Sigbritt Ernald provided a rich source of suggestions for suitable interesting persons to invite for the stimulating and highly enjoyable oral and musical presentations. While the responsibilities of the SOC are quite pleasant and frankly not particularly demanding, the heavy burden with organizing a conference falls squarely with the Local Organizing Committee, which has to deal with a seemingly never-ending stream of practicalities and more mundane chores. The main reason the Stellar Journey conference was such an astounding success and ran so smoothly is the tireless work by the whole LOC. All of us owe a great deal of gratitude to Paul Barklem, Nils Bergvall, Norbert Christlieb, Bengt Edvardsson (Chair), Kjell Eriksson, Ulrike Heiter, Susanne Höfner, Andreas Korn, Nikolai Piskunov, Bertrand Plez and Astrid Wachter for their extensive efforts. I'd like to also extend a special acknowledgement to all of the Uppsala students who helped out during the reception, registration and various sessions. Last but not the least, I'd like to thank all of the conference participants for giving such excellent talks and for providing stimulating discussions throughout the week. It is telling that essentially everyone invited to participate in the conference almost immediately accepted while the very few who declined did so only reluctantly due to other prior commitments. Bengt is a highly regarded colleague and friend, whom we all wished to celebrate this special occasion with. This conference represented merely one brief stop on a marvellous and truly stellar journey. I dare say that without exception we are all deeply thankful for having been able to join Bengt Gustafsson on at least some of his many cosmic adventures during the past decades. We trust that this exciting odyssey will continue for many years.

a Passage to the Universe

NASA Astrophysics Data System (ADS)

1995-11-01

a concluding Press Conference , during which the outcome of this unique event will be summarized by the participants and the organisers: Monday, November 20, 1995, 15:30 pm, at the ESO Headquarters, Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany List of National First-Prize Winners Belgium: Mr. Freddy Allemeersch (Teacher), Mr. Pieter De Ceuninck, Mr. Jeroen Staelens (Onze-Lieve-Vrouwecollege, Brugge) Denmark: Mr. Joern C. Olsen, Mr. Henrik Struckmann, Mr. Uffe A. Hansen, Mr. Mogens Winther (Teacher) (Soenderborg Amtsgymnasium) Finland: Mr. Reima Eresmaa, Ms. Laura Elina Nykyri, Ms. Reetamaija Janhonen (Cygnaeues-Lukeo, Jyvaeskylae and Jyvaeskylaen Lyseon Lukeo) France: Mr. Rene Cavaroz (Teacher), Mr. Vincent Hardy, Mr. Antoine Lesuffleur (Lycee Chartier, Bayeux) Germany: Ms. Dorothee Barth, Mr. Walter Czech (Teacher), Mr. Uwe Kranz, Ms. Karin Wieland (Immanuel-Kant-Gymnasium, Leinfelden-Echterdingen, Baden-Wuerttemberg) Greece: Ms. Agni Ioannidi, Ms. Elena Katifori, Mr. Vassilis Samiotis, Mr. Vassillos Tzotzes (Teacher) (Second Varvakelo Experimental Lyceum, Athens) Ireland: Mr. Declan Maccuarta (Teacher), Mr. Colm Mcloughlin (St. Peter's College, Wexford, Co. Wexford) Italy: Mr. Pasquale Ciarletta, Ms. Francesca D'elia, Ms. Ada Fortugna (Teacher), Mr. Alfredo Pudano (Liceo Scientifico `Leonardo da Vinci', Reggio Calabria) The Netherlands: Mr. Alex De Beer, Mr. Klaas Huijbregts, Mr. Ruud Nellen (Norbertuscollege, Rosendaal) Spain: Mr. Aritz Atela Aio, Mr. Julen Sarasola Manich (Teacher), Mr. Jon Huertas Rodriquez (Txorierri Batxilergoko Institua, Derio Bizkaia) Sweden: Mr. Rahman Amanullah, Mr. Kjell L. Bonander (Teacher), Mr. Tomas Oppelstrup, Ms. Christin Wiedemann (Saltsjoebadens Samskola, Saltsjoebaden) United Kingdom: Mr. Michael Ching, Dr. Richard Field (Teacher) (Oundle School, Peterborough) National Committees Further information about the national contests may be obtained from the National Committees: Belgium: Dr. C. Sterken, Vrije Universiteit

32nd International Austrian Winter Symposium : Zell am See, the Netherlands. 20-23 January 2016.

PubMed

Langsteger, W; Rezaee, A; Loidl, W; Geinitz, H S; Fitz, F; Steinmair, M; Broinger, G; Pallwien-Prettner, L; Beheshti, M; Imamovic, L; Beheshti, M; Rendl, G; Hackl, D; Tsybrovsky, O; Steinmair, M; Emmanuel, K; Moinfar, F; Pirich, C; Langsteger, W; Bytyqi, A; Karanikas, G; Mayerhöfer, M; Koperek, O; Niederle, B; Hartenbach, M; Beyer, T; Herrmann, K; Czernin, J; Rausch, I; Rust, P; DiFranco, M D; Lassen, M; Stadlbauer, A; Mayerhöfer, M E; Hartenbach, M; Hacker, M; Beyer, T; Binzel, K; Magnussen, R; Wei, W; Knopp, M U; Flanigan, D C; Kaeding, C; Knopp, M V; Leisser, A; Nejabat, M; Hartenbach, M; Kramer, G; Krainer, M; Hacker, M; Haug, A; Lehnert, Wencke; Schmidt, Karl; Kimiaei, Sharok; Bronzel, Marcus; Kluge, Andreas; Wright, C L; Binzel, K; Zhang, J; Wuthrick, Evan; Maniawski, Piotr; Knopp, M V; Blaickner, M; Rados, E; Huber, A; Dulovits, M; Kulkarni, H; Wiessalla, S; Schuchardt, C; Baum, R P; Knäusl, B; Georg, D; Bauer, M; Wulkersdorfer, B; Wadsak, W; Philippe, C; Haslacher, H; Zeitlinger, M; Langer, O; Bauer, M; Feldmann, M; Karch, R; Wadsak, W; Zeitlinger, M; Koepp, M J; Asselin, M-C; Pataraia, E; Langer, O; Zeilinger, M; Philippe, C; Dumanic, M; Pichler, F; Pilz, J; Hacker, M; Wadsak, W; Mitterhauser, M; Nics, L; Steiner, B; Hacker, M; Mitterhauser, M; Wadsak, W; Traxl, A; Wanek, Thomas; Kryeziu, Kushtrim; Mairinger, Severin; Stanek, Johann; Berger, Walter; Kuntner, Claudia; Langer, Oliver; Mairinger, S; Wanek, T; Traxl, A; Krohn, M; Stanek, J; Filip, T; Sauberer, M; Kuntner, C; Pahnke, J; Langer, O; Svatunek, D; Denk, C; Wilkovitsch, M; Wanek, T; Filip, T; Kuntner-Hannes, C; Fröhlich, J; Mikula, H; Denk, C; Svatunek, D; Wanek, T; Mairinger, S; Stanek, J; Filip, T; Fröhlich, J; Mikula, H; Kuntner-Hannes, C; Balber, T; Singer, J; Fazekas, J; Rami-Mark, C; Berroterán-Infante, N; Jensen-Jarolim, E; Wadsak, W; Hacker, M; Viernstein, H; Mitterhauser, M; Denk, C; Svatunek, D; Sohr, B; Mikula, H; Fröhlich, J; Wanek, T; Kuntner-Hannes, C; Filip, T; Pfaff, S; Philippe, C; Mitterhauser, M; Hartenbach, M; Hacker, M; Wadsak, W; Wanek, T; Halilbasic, E; Visentin, M; Mairinger, S; Stieger, B; Kuntner, C; Trauner, M; Langer, O; Lam, P; Aistleitner, M; Eichinger, R; Artner, C; Eidherr, H; Vraka, C; Haug, A; Mitterhauser, M; Nics, L; Hartenbach, M; Hacker, M; Wadsak, W; Kvaternik, H; Müller, R; Hausberger, D; Zink, C; Aigner, R M; Cossío, U; Asensio, M; Montes, A; Akhtar, S; Te Welscher, Y; van Nostrum, R; Gómez-Vallejo, V; Llop, J; VandeVyver, F; Barclay, T; Lippens, N; Troch, M; Hehenwarter, L; Egger, B; Holzmannhofer, J; Rodrigues-Radischat, M; Pirich, C; Pötsch, N; Rausch, I; Wilhelm, D; Weber, M; Furtner, J; Karanikas, G; Wöhrer, A; Mitterhauser, M; Hacker, M; Traub-Weidinger, T; Cassou-Mounat, T; Balogova, S; Nataf, V; Calzada, M; Huchet, V; Kerrou, K; Devaux, J-Y; Mohty, M; Garderet, L; Talbot, J-N; Stanzel, S; Pregartner, G; Schwarz, T; Bjelic-Radisic, V; Liegl-Atzwanger, B; Aigner, R; Stanzel, S; Quehenberger, F; Aigner, R M; Marković, A Koljević; Janković, Milica; Jerković, V Miler; Paskaš, M; Pupić, G; Džodić, R; Popović, D; Fornito, M C; Familiari, D; Koranda, P; Polzerová, H; Metelková, I; Henzlová, L; Formánek, R; Buriánková, E; Kamínek, M; Thomson, W H; Lewis, C; Thomson, W H; O'Brien, J; James, G; Notghi, A; Huber, H; Stelzmüller, I; Wunn, R; Mandl, M; Fellner, F; Lamprecht, B; Gabriel, M; Fornito, M C; Leonardi, G; Thomson, W H; O'Brien, J; James, G; Hudzietzová, J; Sabol, J; Fülöp, M

2016-04-01

-through reactorS Pfaff, C Philippe, M Mitterhauser, M Hartenbach, M Hacker, W WadsakA22 Influence of 24-nor-ursodeoxycholic acid on hepatic disposition of [18F]ciprofloxacin measured with positron emission tomographyT Wanek, E Halilbasic, M Visentin, S Mairinger, B Stieger, C Kuntner, M Trauner, O LangerA23 Automated 18F-flumazenil production using chemically resistant disposable cassettesP Lam, M Aistleitner, R Eichinger, C ArtnerA24 Similarities and differences in the synthesis and quality control of 177Lu-DOTA-TATE, 177Lu -HA-DOTA-TATE and 177Lu-DOTA-PSMA (PSMA-617)H Eidherr, C Vraka, A Haug, M Mitterhauser, L Nics, M Hartenbach, M Hacker, W WadsakA25 68Ga- and 177Lu-labelling of PSMA-617H Kvaternik, R Müller, D Hausberger, C Zink, RM AignerA26 Radiolabelling of liposomes with 67Ga and biodistribution studies after administration by an aerosol inhalation systemU Cossío, M Asensio, A Montes, S Akhtar, Y te Welscher, R van Nostrum, V Gómez-Vallejo, J LlopA27 Fully automated quantification of DaTscan SPECT: Integration of age and gender differencesF VandeVyver, T Barclay, N Lippens, M TrochA28 Lesion-to-background ratio in co-registered 18F-FET PET/MR imaging - is it a valuable tool to differentiate between low grade and high grade brain tumor?L Hehenwarter, B Egger, J Holzmannhofer, M Rodrigues-Radischat, C PirichA29 [11C]-methionine PET in gliomas - a retrospective data analysis of 166 patientsN Pötsch, I Rausch, D Wilhelm, M Weber, J Furtner, G Karanikas, A Wöhrer, M Mitterhauser, M Hacker, T Traub-WeidingerA30 18F-Fluorocholine versus 18F-Fluorodeoxyglucose for PET/CT imaging in patients with relapsed or progressive multiple myeloma: a pilot studyT Cassou-Mounat, S Balogova, V Nataf, M Calzada, V Huchet, K Kerrou, J-Y Devaux, M Mohty, L Garderet, J-N TalbotA31 Prognostic benefit of additional SPECT/CT in sentinel lymph node mapping of breast cancer patientsS Stanzel, G Pregartner, T Schwarz, V Bjelic-Radisic, B Liegl-Atzwanger, R AignerA32 Evaluation of diagnostic value

Salt or ice diapirism origin for the honeycomb terrain in Hellas basin, Mars?: Implications for the early martian climate

NASA Astrophysics Data System (ADS)

Weiss, David K.; Head, James W.

2017-03-01

origin unlikely. Diot et al. (2016) noted, however, that brittle deformation features are not expected during "passive" downbuilding of diapirs, wherein diapirs propagate upwards at the same rate as they are buried by sediment (Jackson et al., 1994), and Bernhardt et al. (2016a) note that some terrestrial salt diapirism is associated with more ductile, rather than brittle surface deformation, and so the lack of brittle deformation features may not explicitly preclude a salt diapir origin. Bernhardt et al. (2016a) further suggest that the volume of water necessary to produce the thick salt deposits may be as low as a ∼3.5 m global equivalent layer (GEL) of water (∼506 000 km3), assuming fully saturated saline water, and that such a water volume could have been present and recycled throughout the Noachian period (e.g., Rosenberg and Head, 2015). Bernhardt et al. (2016a) conclude that a salt diapir origin for the honeycomb terrain remains a viable candidate formation hypothesis. They performed a preliminary assessment of the diapir-forming layer thicknesses required to produce the observed diapir wavelengths and found that a salt layer must be at least ∼2 km thick and superposed by an overburden between ∼2 and ∼4 km thick to produce the observed diapir wavelengths.We also note that the elongate morphology of the honeycomb terrain (Fig. 1C) is consistent with a diapir origin. Terrestrial salt diapirs are commonly elongated (Fails et al., 1995, pp. 27; Hudec and Jackson, 2007). Elongation can be caused by (1) the local stress field generated by pre-existing faults, (2) a specific tectonic regime, (3) underlying bed slope, or (4) salt thickness variations (Jackson and Talbot, 1986; Harding and Huuse, 2015), or alternatively (5) by variations in the sedimentation rate forming the overlying layer (Fernandez and Kaus, 2015). Ice diapirism:Diot et al. (2016) and Bernhardt et al. (2016a) assessed whether the honeycomb terrain could alternatively be

Mixing and turbulent mixing in fluids, plasma and materials: summary of works presented at the 3rd International Conference on Turbulent Mixing and Beyond

NASA Astrophysics Data System (ADS)

Gauthier, Serge; Keane, Christopher J.; Niemela, Joseph J.; Abarzhi, Snezhana I.

2013-07-01

was held in the summer of 2011 at the Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy. The papers are arranged by TMB themes, and within each theme they are ordered alphabetically by the last name of the first author. The collection includes regular research papers, a few research briefs and review papers. The review papers are published as 'Comments' articles in Physica Scripta . Canonical turbulence and turbulent mixing. Six papers are devoted to canonical turbulence and turbulent mixing. Baumert presents a theory of shear-generated turbulence, which is based on a two-fluid concept. Gampert et al investigate the problem of adequate representation of turbulent structures by applying a decomposition of the field of the turbulent kinetic energy into regions of compressive and extensive strain. Paul and Narashima consider the dynamics of a temporal mixing layer using a vortex sheet model. Schaefer et al analyse the joint statistics and conditional mean strain rates of streamline segments in turbulent flows. Sirota and Zybin deepen their discussion of the connection between Lagrangian and Eulerian velocity structure functions in hydrodynamic turbulence. Talbot et al investigate the heterogeneous mixing by considering gases of very nearly equal densities and very different viscosities. Wall-bounded flows. Three papers are dedicated to wall-bounded flows. Mok et al use the Bayesian spectral density approach to identify the dominant free surface fluctuation frequency downstream of an oscillating hydraulic jump. Tejada-Martinez et al employ large eddy numerical simulations to study wind-driven shallow water flows with and without full-depth Langmuir circulation (parallel counter rotating vortices). Wu et al re-evaluate the Karman constant based on a multi-layer analytical theory of Prandtl's mixing length function. Non-equilibrium processes. This theme is represented by two papers. Chasheckhin and Zagumennyi consider non-equilibrium processes

The Glory of a Nearby Star

NASA Astrophysics Data System (ADS)

2001-08-01

and coronae. More information The research reported in this Press Release is described in a scientific article ("Light from Stellar Coronae: Ground-based Discovery of Emission Lines" by Jürgen Schmitt and Reiner Wichmann ) that appears in the August 2, 2001, issue of the scientific journal "Nature". Jürgen Schmitt has written a popular account on stellar X-ray emission in the German language journal "Sterne und Weltraum" (July 2001, page 544). Note [1]: A report on the observations of the 1869 solar eclipse appeared in the first Nature issue (November 4, 1869) and the interesting story about the identification of the solar coronal lines is described in a popular article ( John Talbot ). A talk by Herbert Friedman about the evolution of X-Ray Astronomy includes a description of the 1949 detection of solar emission in this waveband. More details about the solar-stellar connection and X-rays may be found in the article by Berhard Haisch and Jürgen Schmitt in the October 1999 issue of the journal "Sky & Telescope" (page 46).

Young Astronomers' Observe with ESO Telescopes

NASA Astrophysics Data System (ADS)

1995-11-01

system (with the name `Ngnz'i'!), consisting of a central star that is somewhat larger than the Sun and situated at the same distance as the Sun from the centre of the Milky Way System (31,700 light-years). The distance from the Sun is twice as large, 63,400 light-years. Circling the central star at a distance of 300 million kilometres, there is a double planet with a revolution period of just over 3 years. The conditions on another planet further out is suitable for life and it harbours frog-like intelligent beings. Two outer, gaseous planets complete this system. Spain: Mr. Aritz Atela Aio, Mr. Julen Sarasola Manich (Teacher), Mr. Jon Huertas Rodriquez (Txorierri Batxilergoko Institua, Derio Bizkaia) The group built its own f/8 Newtonian reflector with a main mirror of 20 cm diameter. They tested it on various astronomical objects and found that it produced quite good images. Then they put together their own CCD camera from spare parts; the frame size is about 5 x 4 mm with a total of 300,000 pixels. With this special equipment, they have observed the major Jovian moons as they revolve around Jupiter. They projected the image on a TV-screen and measured the exact positions of the moons, relative to Jupiter, on this screen. In this way, they were able to determine the periods of revolution of the moons and from the diameters of the orbits and Jupiter's size, they could determine Jupiter's mass and mean density. Sweden: Mr. Rahman Amanullah, Mr. Kjell L. Bonander (Teacher), Mr. Tomas Oppelstrup, Ms. Christin Wiedemann (Saltsjoebadens Samskola, Saltsjoebaden) In another Universe, three heroes meet on a far-away planet, named Magrathea. They check the computerized data archive available there, discovering a reference to the planetary system Ikaros III, and a description of its formation and evolution. At the centre is an A-type star, Ikaros; the temperature is 9700 K, and its lifetime is about 500 million years. It is surrounded by three planets, whose physical

Houston, We Have a Podcast. Episode 22: Astronaut Health

NASA Image and Video Library

2017-12-07

[00:00:00] Gary Jordan (Host): Houston, we have a podcast! Welcome to the official podcast of the NASA Johnson Space Center, Episode 22, Astronaut Health. I'm Gary Jordan, and I'll be your host today. So on this podcast, we bring in the experts, NASA scientists, engineers, astronauts, all the coolest people! We bring them right here on the show to tell you about more everything NASA. So today, we're talking about astronaut health with Natacha Chough. She's a flight surgeon here at the NASA Johnson Space Center in Houston, Texas, and she gave a great description about what a flight surgeon does and how they work with astronauts to monitor their health during spaceflight. So thanks to future doctor spaceman for the suggestion on Twitter for an episode with a flight surgeon. If you have suggestions for the topic you'd like to hear on the show, let us know! You can find where to submit everything at the end of every episode. No, I'm not going to reveal it right up front, you got to listen to the whole thing. Plus, this is a really good conversation anyway. You're going to really enjoy it. So, with no further delay, let's go lightspeed and jump right ahead to our talk with Dr. Natacha Chough. Enjoy! [00:00:59] [ Music ] [00:01:12] [ Music & Radio Transmissions ] [00:01:18] [ Music ] Host: Now, we'll -- we'll start with something happy. Natasha, thanks so much for coming on the show, ran into your profile as part of Peggy's NASA Village Project, you're one of the many people that supported Peggy Whitson, right, during her flight. So how was it -- what was it like working with the space ninja? [00:01:36] Natacha Chough: So I think as anyone who works with Peggy will tell you, she is awesome at what she does! [Laughing] And she's just a joy to watch. Plus she's a wonderful person, which just makes it even better. [00:01:46] Host: Oh yeah. Yeah, definitely. Just in the few interactions I've had with her where, you know, interviews or her dealing with media, just, you know, sitting down in the chair with a lot of people looking at her, lights, cameras, and she's just laughing, having a good time. It's just, you know, you really appreciate that when you're on -- when you're on the behind-the-scenes stuff and you know the pressure that goes into it. But you were -- for supporting her, you're a flight surgeon, right? [00:02:07] Natacha Chough: So I wasn't assigned to her as her crew surgeon, but I was -- after her landing, her in two fish [phonetic], I was the physician on the NASA aircraft that brought them back to Houston. [00:02:19] Host: Oh, okay. So you were out -- you were out in Kazakhstan then? [00:02:23] Natacha Chough: So, actually, this landing happened right after Harvey, and because of the multiple personnel impacts that NASA had, including to our aircraft operations division, we weren't able to get our aircraft staged in Kazakhstan in time for their landing. So, what happened was we got the help from the European Space Agency, so they had an aircraft and they went and got our crew in Kazakhstan and brought them back to Cologne, Germany, use the headquarters, and then we went to Cologne to pick up our crew there. [00:02:52] Host: Okay. [00:02:52] Natacha Chough: So that was like a total modified... [00:02:54] Host: Yeah! [00:02:55] Natacha Chough: ...expected direct return operation, yeah. [00:02:57] Host: So you went from Houston to Germany then? Okay. And you were -- so you were -- so what is -- what is that? What's a doctor on-call? [00:03:04] Natacha Chough: We call it the air doc. [00:03:07] Host: Air doc. [00:03:07] Natacha Chough: Yeah. So NASA has an aircraft that we use to bring back our crew from landing within 24 hours, and the -- the purpose of that is just so the science and research folks can get data as soon as possible once the crew returned, just because there's a lot of physiologic changes that happen. You know, not only right after landing, but in the -- the hours and days that follow. [00:03:30] Host: Okay, yeah, and you have to just kind of -- so, what's your job? Your job is to monitor it, record it, to help it? [00:03:36] Natacha Chough: We do take some samples and stuff in flight on return, but, you know, the crew can be pretty symptomatic in terms of like returning to a 1G environment, and so we kind of mitigate a lot of the symptoms that they're having, motion sickness, that type of thing, in the early hours, post-landing. [00:03:54] Host: So now you're a -- you're a flight surgeon now, right? Who's your crew members that you're working with? [00:03:59] Natacha Chough: So currently I'm assigned to Jeanette Epps, and she's launching next spring. [00:04:03] Host: Okay. Okay. So you -- what's some of the stuff you have to do this early ahead of time? [00:04:08] Natacha Chough: So right now, we just did her L minus 6 months physical, make sure that, you know, she's still within standards for long duration spaceflight. She's actually out of the country right now because in this part of the pre-launch timeframe, she and Alex [inaudible], he's a crew member, and then Sergei [inaudible], the Russian crew member, they're all serving as the backup crew to the prime crew that's launching this December. [00:04:33] Host: Oh, okay. So they're out there with Scott Tingle and [inaudible] and those guys? Okay, cool. Very cool. So you're -- you don't have to follow them for that then? You get to stay here? [00:04:43] Natacha Chough: Yeah. In the meantime, you know, there's a lot of just like pre-travel prep, making sure all of us, including the docs, are up on our immunizations for, you know, upcoming travel. In the next few months before launch, we'll also get together with her in our pharmacy, and make sure that she's got any prescription meds she takes on a regular basis put in these ISS medical accessory packs, people take, you know, nutritional supplements or daily vitamins or whatever, we make sure that all that is packed for them and any motion sickness meds they might need on the way up. [00:05:13] Host: Okay. So how long have you been in the flight director, or not flight director, flight surgeon role? [00:05:18] Natacha Chough: So I got hired on full-time here a little over two and a half years ago. [00:05:22] Host: Okay, cool. Alright. So let's -- let's back up just a little bit from -- from all this and talk about, what is a flight surgeon? Right? Let's start -- let's do that. [00:05:32] Natacha Chough: Yeah, so I got to tell you it is the coolest, yet most misleading job title there is, because we don't fly in space, and the vast -- vast majority of us aren't actual surgeons. What a flight surgeon is is a medical doctor who takes care of pilots and astronauts. But the job title is a total misnomer, it's kind of like -- I think of like the surgeon general of the United States, right? So most of these aren't actual surgeons. So for those who are listening who aren't military buffs, basically, dating back to like early wars, actual surgeons were the predominant type of medical doctor on the battlefield, and then that term has stuck in the military at NASA. And the flight part of the job title indicates, you know, that we take care of pilots and astronauts, but it also implies that we have at least some flying experience ourselves, either as private pilots, student pilots, or, you know, riding in the backseat of the T38, the NASA training jet, along with our crew members. So, that flight experience is actually key to understanding the physiology of the flight environment that our patients experience, as well as the psychology and the human factor aspect of like how they interface with engineering design and aircraft controls, and all that's especially important for maintaining crew safety. [00:06:42] Host: How about that? So what are some of the main differences then? Like what -- what separates, you know, what makes you have that flight thing? What are some of the considerations whenever I guess the human body is in flight? [00:06:54] Natacha Chough: Right. So, in flight, depending on the different types of maneuvers you're going to be doing, like if you've been to an airshow, aerobatic pilots can do, you know... [00:07:04] Host: Crazy stuff! [00:07:04] Natacha Chough: A lot of [inaudible] maneuvers, and depending on the order in which they do them, it can change, you know, blood rushing to your head versus blood rushing to your feet, and if you do that [laughing] in a very provocative way, you run the risk of what pilots refer to as graying out or blacking out and losing consciousness momentarily. So you never want those types of incapacitating events to happen in flight. And that's what we try to prevent. Another big thing that we learn about is hypoxia, right, so lack of oxygen. And so if you're cabin, for whatever reason, depressurizes and you are, you know, at the equivalent of tens of hundreds of feet, you know, above sea level, that's going to feel a lot different than a cabin that's pressurized to a more normal environment. So our regular aircraft that all of us fly commercially, like a Southwest aircraft, for example, is pressurized to 8,000 feet and most of us can tolerate that, but if you have a depressurization and all of a sudden you're at the equivalent of 30,000 feet, obviously, your time of useful consciousness, or the amount of time it's going to take before you pass out because you -- there's not enough oxygen up there at that altitude is, you know, goes down to seconds. [00:08:13] Host: Wow. [00:08:14] Natacha Chough: So those are the types of things that we have to learn about, and then, you know, we train along with crew to understand what our particular symptoms are in that situation, because it can be a little bit different for different people. Some people get a little bit loopy. Some people have spotty vision, some people get shaky, it really depends. [00:08:31] Host: Oh yeah, there's -- is that -- is it hypobaric chamber? [00:08:36] Natacha Chough: Hypobaric. Yep. [00:08:37] Host: Hypobaric, where they actually -- they'll do that, right? [00:08:39] Natacha Chough: Exactly. [00:08:40] Host: You go in there, they'll bring down the pressure, and they'll just like watch you and then write down some stuff. I actually had a friend that did that. She works in the MBL, and hers was actually -- she said she -- nothing happened to her. And I was like, oh, that's cool, and she's like, no. [00:08:55] Natacha Chough: That's actually bad. [00:08:56] Host: Yeah! Exactly! And it's because, right, you need to think about your symptoms. [00:09:00] Natacha Chough: Right. And if you don't have any symptoms, you could pass out like that, and we never want that to happen when you're at the controls of an aircraft or, you know, if you're on an EVA and that happens for whatever reason. [00:09:12] Host: Okay. So, do you understand -- when you're a flight surgeon, you understand the -- what happens for your -- the crew members that you're taking care of? [00:09:21] Natacha Chough: Right. And another thing that they do in training is a CO2 exposure class. So carbon dioxide is different on station than it is on earth, right? The levels are different. Because here on earth, if a room gets stuffy, we can just open the window, you can't really do that on station. So, crew are exposed to about 8 minutes of carbon dioxide. It's basically they're breathing into a bag and they're rebreathing their -- their own expired air during these 8 minutes. And they write down their symptoms for that, as well. And that's really important because if levels tend to creep up on station, they have an idea, from this exposure class, you know, what their symptoms are and whether it's potentially attributable to the CO2 levels on station. [00:10:06] Host: Wow. There's a lot of tests for [laughter] being a flight surgeon where they just put you through the ringer! Alright, well, we're going to deprive you of like pressure and see what happens. Alright, keep breathing your own CO2, see what happens. What other kind of tests are like that? [00:10:19] Natacha Chough: Well, I've definitely done the hypobaric -- hypobaric chamber, you know, hypoxia demonstration more times than I can count now. So I think I've lost enough brain cells at this point, but, you know, a lot of it too is -- is written tests and stuff as you're going through like medical specialty training, so. [00:10:34] Host: Okay. Because I know like they -- they do egress training for -- I've seen the ones for Orion, I think, where they actually jump in and I don't know if there's some health considerations there for where a flight surgeon would be for that test. [00:10:46] Natacha Chough: There are. So, you know, Orion is supposed to splash down in the water, and after you've been in space for a long time, that rocking motion in the spacecraft can be really provocative when you're already motion sick, and so, you know, there's certain parameters as to how much rocking we would like versus -- versus not, and, you know, what all that is going to look like. So, people way smarter than me are working on that. [00:11:10] Host: [Laughing] So, when you're -- when you're assigned a crew member, what -- at what point do you start working with them, and at what point do you kind of say, you're done, and you kind of can go onto the next crew member or something? [00:11:22] Natacha Chough: So we usually get assigned to them about a year in advance or so. [00:11:26] Host: Okay. Of their launch? [00:11:28] Natacha Chough: Of their launch. Yeah. It can be as soon as like -- as early as 18 months pre-launch. And so it definitely ramps up like exponentially the closer you get to launch. Like I mentioned, if, you know, if you're in Star City is the physician and you're supporting them through some of the Russian medical training that they do there, when they're here doing training in the MBL, the MBL during their suited run, we also support their vacuum chamber runs in Building 7, which is where they test their AVA suit and make sure that it functions at vacuum. And then there's, on the medical side, there's actually a lot of medical training that they crew get, because there's no requirement right now that there's a physician on station, but each expedition is assigned to CMOs, or chief medical officers, and those are US OS crew members who have a little bit of additional medical training, and so that can include, you know, putting in stitches or temporary dental fillings if needed, those types of things. [00:12:32] And so we've got -- we work with really talented nurses who help train our crew on how to draw their own blood, how to start IVs, all that type of thing. [00:12:40] Host: Oh, okay. And a lot of them are doing studies like that, just normally, right? [00:12:44] Natacha Chough: Some of it is research-based. [00:12:45] Host: Some research-based stuff, I guess besides the medical side, but, okay. So then you -- if they -- if there's no physician on the station, the backup is to have a physician on the ground, right? That's the -- that's the normal way of doing things, and flight surgeons sit in mission control. So is that part -- like, how often are you doing that? [00:13:05] Natacha Chough: So, when you're assigned to a mission, you're on counsel a few times out of the week and -- and that's only because you rotate with other crew surgeons who are working that same expedition. [00:13:16] Host: Oh, okay. So, you're -- it's not just you, it's like a team. [00:13:18] Natacha Chough: It's like a team of 4. Right? So like each Soyuz launch, on the NASA side at least, has one prime crew surgeon and one deputy crew surgeon who's their backup, essentially. And then it's usually two Soyuz crews at a time, and so that's what makes up the -- the four docs that kind of rotate sitting in console. [00:13:35] Host: There you go. So what are you looking at when you're on console? [00:13:38] Natacha Chough: So on console, on a regular day, we mostly focus on the -- the station, what we call the bio environmentals. I like to call it the vital signs on station. Right, so like, what's the CO2 level today? Like what's the pressure, you know, in the modules that the crew is working in, what's the O2 level? What's the temperature? What's the humidity? And then we look at their timeline everyday, so as you probably know, the schedule for each crew member is planned out to like 5 minute increments. [00:14:06] Host: Oh yeah. [00:14:07] Natacha Chough: So, there's always reviews of plans for, you know, the current day, one day out, three days out, seven days out, and so we're just verifying to make sure that, you know, everyone's got two hours of exercise blocked off that, you know, on most days, unless there's an extenuating circumstance, everyone's eating lunch together, because that's really good for, you know, crew psychology, and then making sure that there's nothing, you know, that's unnecessarily interrupting sort of their wind-down period at the end of the day before they go to sleep. It's kind of like if you got called about something for work at like 9 o'clock at night. You know what I mean? So, we try and like really minimize that kind of thing, and then, overall, we also have to approve any overages to their kind of weekly duty hours to make sure that they're not, you know, at risk of bringing out for like working too long of a week, and so if -- if that ever happens, we have weekly meetings with the flight director to make sure that that time is made up the following week, if they get a day off or some time off, subsequently. [00:15:06] Host: So you must be really close with the astronauts then, because you're the one that actually protects them from working. [00:15:10] Natacha Chough: Yeah, so, I mean, yeah, the role of the flight doc these days, you know, back in World War I when flight docs were started, I feel like there was a little bit of animosity, right? [Laughing] Like between flight docs and -- and military fliers, because, you know, the best that you could ever do is come out even from an employment with your flight doc. You know, the worst that you could come out is that they would ground you for some medical reason, but these days it's a lot more -- we're definitely their advocate, right, and want to make sure that we create an environment that is conducive of them, you know, flying happily and safely and healthily. [00:15:46] Host: Yeah. I mean, what -- what is -- what does a flight surgeon do to make sure that they are in a state of mind where they can perform hundreds of experiments and -- and do all the tasks that are assigned to them on a daily basis? [00:15:58] Natacha Chough: So that's actually something that our behavioral health and performance group focuses on, and we work in consultation with them, but, essentially, we've got crew psychologists and crew psychiatrists that are assigned to each crew member, and then, you know, before their mission, they meet with them on a regular basis, and then during the mission, they have what they call PPCs, or private psychological conferences every couple of weeks, and those docs also will be in touch with the crew member's family. Especially after events like Harvey, right? Something totally unplanned and that can be a huge stressor for -- for folks on orbit and their family members on the ground. [00:16:40] Host: Oh, yeah. [00:16:40] Natacha Chough: Yeah. So, they're very good about, you know, before astronauts are even selected, like screening for people who are psychologically, you know, very stable. Once they're selected, making sure that they have all the resources that they have pre-mission, during mission, they talk about, you know, if there's bad news, how do you want it to be delivered? Who do you want to deliver the news? How do you want them to deliver it? So, that group is really, I think, paramount to crew well-being, and then keeping the family members in the loop as well with regular communication. [00:17:14] Host: So that's -- that's just not flight surgeon job then, is it? [00:17:17] Natacha Chough: No, it's more -- yeah, it's BHP. [00:17:19] Host: BHP. Yeah, exactly. What -- what qualifies an astronaut as being able to go to space, medically, healthy? [00:17:26] Natacha Chough: So, what we look for is overall medical fitness for the pressures of spaceflight, and that begins, like I mentioned, with, you know, selection criteria during the application process. So once they're selected, if they have an illness or an injury, we get them treatment and the specialty care that they need, and then we have an air medical board that actually reviews their case files on a regular basis to recertify them for flight if they happen to be grounded for whatever reason. It's actually similar to how the military and the FAA medically certify their pilots. And as a taxpayer, for those of you listening out there, so these processes are also in existence to help keep the general public safe. So, in general, the FAA has a role to keep the risk of a pilot having an incapacitating medical event to less than 1 percent. [00:18:15] Host: Alright. [00:18:17] Natacha Chough: So, we kind of follow very similar standards. But in order for crew to stay healthy, essentially, they have to train, right? So, like I mentioned, we work with really talented physical trainers, psychiatrists, psychologists, pharmacists, nurses, to make sure that our crew are not only physically and mentally ready for long-duration spaceflight, but they're also capable to administer medical care to each other if necessary. [00:18:45] Host: Okay, are you overseeing their -- their workouts and stuff like that? Or is that a totally different thing? [00:18:50] Natacha Chough: So that's the job of our ACERS, so those are astronaut strength, conditioning, and rehab specialists, it's their personal trainers, essentially. So when crew go to orbit, they are actually given what we call an exercise prescription. And they've got different goals that they can work towards and -- and modify if needed in space, and all of that, essentially, is part of our -- it's actually I think one of our most successful countermeasures, right, is maintaining your bone and muscle mass. So we know that maintaining your muscle mass with resistive exercises and getting some sort of impact exercise, like on the treadmill, is really helpful in preventing bone loss and muscle weakness post-flight. [00:19:30] Host: Yeah, definitely. What about -- you said there was a pharmaceutical component to there, are they making sure that they get doses of certain medicines to stay healthy? Like, I don't know if they do calcium supplements or something like that? [00:19:41] Natacha Chough: So, we actually, yeah, we have a great pharmacy here at JSC, and pharmacy helps pack any, you know, regular prescription meds that people fly with, and in addition, you know, they can let us know, there's been some research, there hasn't been enough, but, you know, certain meds just don't do well in space for reasons that we still don't completely understand. So, some -- some medications, if they're in liquid form, will bubble or foam too much to be of any use in space. It's harder to draw them up in a syringe, because you don't have that air -- same air, fluid separation that you do with gravity. So we can't fly those meds, because it's -- it wouldn't be useful. [00:20:19] Host: Right, but they're probably meds that you would need, right? So is there a workaround? [00:20:24] Natacha Chough: So there are alternative meds that we can fly instead, in the meantime, and then we also have medical kits on station with Tylenol and ibuprofen and things like that, if people happen to -- to need those during their mission. [00:20:34] Host: So those -- that's kind of the essential, like, if you're going to fly, this is probably what you're going to need, you know, like the -- stuff like that, just in case some small thing were to come up, oh, I got a slight headache, boom, good to go. [00:20:45] Natacha Chough: Exactly. [00:20:45] Host: Okay, cool. What else besides Tylenol, I guess, that they would -- that they would need? [00:20:49] Natacha Chough: There's antibiotics onboard. If there's, you know, any sort of infection, but it's also, you know, kind of like what you have in your kitchen -- kitchen cabinet. Or, sorry, in your bathroom cabinet [laughing], so Pepto, you know, those types of things. [00:21:03] Host: Okay, cool! [00:21:04] Natacha Chough: But the quarantine process is actually pretty interesting. So I haven't been through that yet myself. I'm the prime doc for Jeanette, so I'll be in quarantine with her, but essentially we go from Star City, Russia, you know, where they train with the Russians, and the entire crew then flies down to Baikonur, Kazakhstan together. And then the prime crew and their prime docs will be in quarantine in Kazakhstan for about two weeks leading up to launch, and so everyday, you know, we take temperatures and do a quick physical exam and there's a Russian epidemiologist down there who's really strict about, you know, who he lets in to visit the crew and stuff, so no kids under 12, that type of thing. And anyone who does want to visit the crew has to, you know, have, you know, written evidence of like 3 days of like no fevers, and... [00:21:54] Host: Wow! [00:21:55] Natacha Chough: Yeah [laughing]. [00:21:56] Host: Alright, pretty -- I mean, it is strict for that reason. Right? They don't want to bring anything up there. So what's the -- have you been in the quarantine environment? [00:22:03] Natacha Chough: No, this will be -- I've visited it, but I haven't stayed there. [00:22:06] Host: Oh. So for Gen X launch, that will be the first time you're going to -- you're going to do it. Okay. [00:22:11] Natacha Chough: Yeah, so I've toured it. There's like a gym, you know, there's a place where they eat meals together and they have folks who are in quarantine with them, like cooks who stay there and cook for them, as well. [00:22:22] Host: Who have also gotten the check? [00:22:24] Natacha Chough: Exactly. Yep. [00:22:25] Host: So it's like a little place for them to live for how long? [00:22:29] Natacha Chough: About two weeks. [00:22:30] Host: Two weeks? Oh, wow. Okay, that's longer than I thought. Yeah, because, you know, you don't want anything to develop, how about that? [00:22:36] Natacha Chough: Right. And then, you know, obviously, flu vaccinations, depending on what time of year you're launching are important for everyone, going down range, to have as well. [00:22:44] Host: Absolutely. Alright, so then they're quarantined and then they go up to the International Space Station. You said they have very limited training when it comes to -- that, you know, they can do small things, but what sorts of things do you prepare for and prepare your crew members for for an emergency? [00:22:59] Natacha Chough: So, actually, they go through what we call megacode training, and so this would be like worst-case scenario, right, like if someone needs CPR. So, we work, again, with our -- our nurse trainers, typically they're nurses with ER backgrounds, and then the flight surgeon, as well, is watching the crew kind of go through this training after they've had a few sessions of hands-on, you know, training with us prior. So, and this is done in the -- the ISS mockup actually. And so we have an AAD [phonetic] on station, if needed. And so they run through, you know, a very modified, but basic algorithm that they would go through in that situation. [00:23:34] Host: Alright. So, okay, and -- and -- in this situation, are you on console helping them out? [00:23:40] Natacha Chough: Yes. So we would, you know, we always have a crew surgeon on console during normal working hours, and then we're on call the rest of the time when we're assigned to that mission. So, if we're not sitting in console on a regular shift, we would get called in for that. [00:23:56] Host: Alright. So no vacations then. You got to stick around in case someone gets pulled in, but that's good, right? Because then, you know, the crew members flying know that, alright, in case of an emergency, I know my -- my flight surgeon's going to be there. So whenever you're designing, you know, procedures, I guess, to do, do you, you know, practice knowing about microgravity? Like, okay, the AAD is going to have to -- we're going to have to do it this way because, you know, you can't just lay someone down, maybe strap them down or something like that? [00:24:24] Natacha Chough: Right. So we actually have a crew medical restraint system on station. And so, the crew know, you know, to put an incapacitated crew member there so that, you know, they don't float away. It's a lot different than it would be on earth. And so, yes, all our procedures are written to -- to account for the microgravity environment. [00:24:40] Host: Okay. Cool. Is there any -- any concerns from the flight surgeon area? Some unique things that flight surgeons in -- at NASA have to deal with that maybe other flight surgeons in the military don't have to worry about because of the microgravity environment? [00:24:55] Natacha Chough: So the biggest thing I'd say, like you mentioned, is, you know, medications, especially like liquids that don't separate from air, and so we're still trying to figure out, you know, how to -- how to work around that [inaudible] is that we do want to fly, but currently can't. [00:25:08] Host: Okay. So it's really just the limitations that... [00:25:10] Natacha Chough: Yeah, and so, you know, they're -- they're industry filters and stuff that -- that neonatal ICUs and that type of thing have worked with and could potentially be helpful. [00:25:20] Host: Cool. So, flight surgeons, I'm trying to think about like your -- your total duties, and they seem -- they seem pretty widespread, right? Like, so you're working with the crew before they launch, when they launch, in mission control, you even talked about some travel, right? You were flying out to Germany, have you been to Kazakhstan or Russia too? [00:25:39] Natacha Chough: Yeah. So, I'm one of the contractor docs, and so part of my job is to be in Star City, Russia where the crew train on Soyuz systems. And so I'm there two to three months out of the year. And that's actually really fun, I kind of like that, it's a very, like, family environment and the crew get together at night and we have family dinners and things like that. [00:26:01] Host: Oh, wow! So it's nice and tightknit. Like, family dinners where? Where they're staying? [00:26:05] Natacha Chough: Yeah, where they're staying. [00:26:06] Host: Okay. [00:26:07] Natacha Chough: Yep. And then -- so I've been to Russia for that and then, yes, I've been to Kazakhstan for a landing as -- as the air doc again on the NASA aircraft. [00:26:16] Host: Cool. NASA aircraft. So that -- was that the G3? [00:26:21] Natacha Chough: It was the G3, now it's G5. [00:26:23] Host: G5. Okay, so then that's the one they take from -- from where to where? [00:26:28] Natacha Chough: From Kazakhstan to Houston, and that's the direct return, what we call direct return within 24 hours of Soyuz landing. [00:26:33] Host: Oh, okay. So you're just watching the recently-landed astronauts and kind of taking care of them? Very cool. Did you take some of the helicopters out to the landing site and all that? [00:26:43] Natacha Chough: I have not actually . So I was on a Russian helicopter for Kate Rubins' launch, I was her deputy crew surgeon. And so for launch, the prime crew doc is, you know, near the launch site with the guest and family members, and then the backup doc, or the deputy doc, which was myself, is in a Russian surgeon rescue helicopter in the event that there's any sort of like launch abort scenario. We would be the ones to fly out to wherever the capsule would have aborted to. [00:27:13] Host: Oh, okay! First responders, boom, you're going. Alright. But you actually did -- you said you flew in the helicopter for Kate Rubins' landing? [00:27:20] Natacha Chough: So you -- they have the blades spinning, but you're staying on the tarmac until you get verification that they've reached orbit. [00:27:28] Host: Okay. [Laughing] Very cool. So what do you have to -- what do you have to study? What do you have to do to be a flight surgeon? Like what's your background? [00:27:35] Natacha Chough: Yeah, so my background is emergency medicine. And then to work at a NASA as a flight surgeon, you need to do an additional residency, and that's medical [inaudible] for specialty training [laughter]. And that residency has to be in aerospace medicine, not flight surgery, that's not a thing. So the expectation, essentially, is that you're a competent physician in whatever your chosen specialty is. [00:28:01] Host: Okay. [00:28:01] Natacha Chough: Before you pursue aerospace medicine because it's such a small and specialized field. I get a lot of questions actually from med students asking what they should specialize in if they want to become a NASA flight surgeon, and I always say, just choose what you love. Because if you love it, you're going to do it better, and that's what people are going to notice, and that's when doors are going to open to you. Because we've had neurologists, urologists, OB/GYNs, become flight surgeons and work here. So it's all about what you enjoy doing. [00:28:26] Host: Yeah, because they're really good, and you said yours was emergency medicine? [00:28:29] Natacha Chough: Yep. [00:28:29] Host: So what was -- what was that -- what were you doing before -- before NASA then in emergency medicine? [00:28:34] Natacha Chough: I actually went straight from emergency medicine residency to the UTMB Aerospace Medicine training program. [00:28:40] Host: Oh, okay. [00:28:41] Natacha Chough: So, yeah, I was just working, you know, 60 to 80 hours a week... [00:28:44] Host: Wow! Alright. [00:28:45] Natacha Chough: ....in the hospital before -- before doing the aerospace program. [00:28:49] Host: Alright. So then what was the aerospace program, how did that -- how do you translate emergency medicine into an aerospace environment? Like, what was different? [00:28:57] Natacha Chough: How did I transition it? I guess the emergency part applies to aerospace medicine in the event of, you know, like a mishap. So -- or planning for a mishap, but not necessarily hoping that that's what happens, right? So it's all about preparing for the worst and hoping for the best. So, emergency medicine, background-wise, can help you figure out what equipment you might need to pack or what equipment you can leave behind. What type of personnel and staffing and other resources you might need at different stages of like a rescue scenario. [00:29:31] Host: Yeah, because I guess you would have to operate assuming that you might have to do something maybe on a site, you know, so you're going to have to bring everything with you or something like that. [00:29:39] Natacha Chough: And you always have to think one step ahead, right? So like let's say I do this first step and it works, but then something else, you know, changes with the patient after that. Then what do I do? And so you have to kind of work out these mental algorithms instead, every possible scenario. [00:29:55] Host: And then from there, you kind of came into the world of NASA, I guess, through... [00:30:01] Natacha Chough: Yeah, so the UTMB Aerospace Medicine program is actually joint with NASA, and so we do some of our rotations here when we are in training, and so one of the ones is working -- is rotating through the flight medicine clinic. And so you're doing some of the astronaut physicals at that time. And then you've got other projects, operationally, that are given to you by different preceptors and mentors. One of my favorite ones was actually doing a one-month rotation with the BHP psychologists and psychiatrists. Just because it's not my specialty, and so I still find it like super interesting though to -- to work with them and see, you know, the types of issues that they deal with, and then interface with the -- the operational flight docs. [00:30:45] Host: Alright, very cool! And now -- now you're here at NASA, now you're a flight surgeon, what's -- it seems like, you know, like I said before, your duties are widespread and you're all over the place, but what's like a -- what's like a day-to-day sort of in the life of a flight surgeon? [00:31:01] Natacha Chough: Yeah, so, it's funny, people are always asking, like, what's a typical day for you? And I'm like, well, I -- I wouldn't say we have typical days, I would say we have typical weeks, but everyday can be a little bit different. So, we are in an engineering community, right? So we're the minority and a lot of times we're looked to as medical consultants, and with station being as complex of a program as it is, there are a lot of meetings with all these different disciplines to make sure that we're doing the right thing and maintaining the health and safety of the crew at the top. So, a lot of times, you know, I'll have a day that's nothing but meetings [laughing], with, you know, potentially questions for me about making, you know, just verifying that like what we're doing isn't medically contraindicated or unsafe in any way. You know, another day I might have my crew member doing a suited run in the MBL and so I'll be there observing that. You know, and another day I might have a couple of meetings in the morning and then in the afternoon my crew member will have some training, medical training, that I'll be attending and just making sure if they have any questions that I'm there. [00:32:05] Host: Okay. Yeah, it seems like your role is more -- is more operational, right? So if something's happening, like, boom, you're there. So, the Neutral Buoyancy Laboratory, that's a good one, right? That one's where the astronauts actually get suited up and practice doing a spacewalk in the pool. [00:32:19] Natacha Chough: Exactly. [00:32:19] Host: Right? So what's -- what's your role? Do you go behind the scenes and kind of check them out beforehand and afterwards? Or is it more you're just kind of standing by watching? [00:32:26] Natacha Chough: Yeah, so everyone who goes in the pool gets a dive physical beforehand. [00:32:29] Host: Dive physical, okay. [00:32:30] Natacha Chough: And then during the run, which is typically about 6 hours, I'll be on the loop just listening and making sure, you know, if there's any medical concerns, they can always request a private loop with the MBL medical director. But as their assigned flight surgeon, it's always good for us to be there, as well, just so we're aware of any issues. [00:32:48] Host: Yeah. Privacy is pretty important when it comes to this stuff, right? [00:32:51] Natacha Chough: Absolutely. [00:32:51] Host: Absolutely, yeah. So that -- your job is kind of -- is kind of like that, right? Whatever you do, you have to make sure that you are protecting the privacy of the astronaut's medical information. So, how does that work I guess in an environment where everyone's talking to each other? Especially in mission control. [00:33:10] Natacha Chough: Yeah. I guess it's not too different from the hospital environment. I think, you know, there are people who interface with us, for example, a biomedical engineer who have essentially [inaudible] of like, you know, a HIPAA, understanding of the HIPAA laws and medical privacy laws and privacy act. [00:33:27] Host: Oh, because they're hearing some of this information too? [00:33:29] Natacha Chough: Right. And, you know, the -- the ones who are involved in these types of conversations are involved because it's a need-to-know basis. And so that's essentially how we operate. [00:33:37] Host: Okay, cool. And you guys have private medical conferences with the astronauts too, right? Like every once in a while, you're checking in. So that's -- is it more of just that? It's just checking in, seeing how everything's going? [00:33:49] Natacha Chough: Yeah, so it's once a week, and it's for about 15 minutes, and it's a video conference direct to station with a crew member on a private loop, and, you know, it's all documented in -- in the chart, the medical chart, from that encounter, will go into the electronic medical record, and so we can always look back and see if there's something that we've been tracking over time, you know, how it's been progressing, but it is mostly a check-in, but, you know, every once in awhile, something will pop up. We know that there are slight immune system changes in space, so, people can get rashes or, you know, just feel stuffier, have allergy-type symptoms. And so a lot of times that's what we deal with. [00:34:31] Host: Okay. So it's -- how much of it is, you know, I guess you're recording, just checking in, and then, you know, sometimes you're going to have to deal with stuff like that, right? So how do you deal with it when you're down here in mission control, but your patient is up in space. [00:34:46] Natacha Chough: Yeah, so that's the art of telemedicine, right, is you can't see and touch and feel your patient yourself. And so we rely on their preflight medical training that we talked about. So they're taught to use, you know, how to use a stethoscope, how to take a blood pressure, how to measure heart rate, that type of thing, and then we have the magic of camera technology up there, so, you know, they can actually look in their crewmates ear and take a picture of what that eardrum looks like and send it down to us. Or they can just take a picture of a rash that's developed and send that down to us, and then, you know, during the private medical conference, we can ask all the other questions, we want to know, how long has it been there, and, you know, is it getting better or worse and what makes it better or worse, those types of things. [00:35:29] Host: Are the things that are normal for spaceflight, like, are there particular, you know, microgravity rashes or something like that that's just typical for being in a space environment or something like that? [00:35:41] Natacha Chough: Rashes can develop, yeah, so that's probably not uncommon, and it's because airflow on station is different than on earth, right? Like particles have weight to them here and there's constant airflow that moves things to different areas. So air doesn't -- heavier molecules don't dissipate or, you know, sink the same way on station. If you're staying motionless, the air particles around you are just going to heat up and you kind of have this like cloak of warmth, right? Or... [00:36:13] Host: Woah! [00:36:14] Natacha Chough: Another example would be if you unpacked something and it had, you know, particles of dust, the dust isn't going to like fall to the ground. [00:36:24] Host: Oh, it's going right up. Yeah. [00:36:25] Natacha Chough: So eye complaints can be a common thing that we hear about after something like that. So we've got protective equipment up there. If -- if we think something's going to be particularly hazardous for them to open or unpack, we recommend that they wear goggles and that type of thing. [00:36:39] Host: Wow! I would not have thought the -- like a heat shield, I guess, that's -- like happening because of the [inaudible]. That's interesting. [00:36:46] Natacha Chough: It's actually documented in Lost Moon, Jim Lovell's book about Apollo 13, when they had to turn a lot of the power systems off, it was really cold in there, but they found if they didn't move around as much, their body heat actually heated the air particles around them. [00:37:02] Host: Woah! [Laughter] That is wild to think about! So that's what I was talking about when I was asking, like, what are some of the microgravity things that are just different? That's perfect! That's exactly what I was -- I would have never thought, like, so -- so if you just stay still, you stay warm, because you're kind of moving, it's just a different air environment. How about that? So I guess are you the one in charge, though, if they are unpacking something, for example? Like, you say, hey, you definitely have to wear goggles for this or something like that? [00:37:31] Natacha Chough: It actually depends on who owns the hardware. But there's a lot of other system interfaces that I'm not privy to that I think come into play, and the biomedical engineer helps us out with that, as well. So they kind of -- biomedical engineers essentially are what -- we call them the nuts and bolts, they work with the nuts and bolts of medical hardware, right? So if the ultrasound machine breaks, they troubleshoot that. If the human breaks for whatever reason, like that's our job, we're the blood and guts. [00:37:58] Host: [Laughing] The blood and guts. [00:37:59] Natacha Chough: Yeah, but the rashes, going back to the rashes, so the -- the reason sometimes rashes develop is, so, back to our example of unpacking something that's new, maybe it's off gassing some sort of particles and those particles, if they're not circulating in the air the same way that they do on earth, can sort of linger in one space, maybe near your skin or something, and that sort of exposure with I guess not as efficient airflow as you would have on earth may make the skin react a little bit. But there's also, like I mentioned, some immune changes that happen and some rashes and allergy-type symptoms can be related to that, as well. [00:38:36] Host: Oh, because your immune system isn't operating as -- as much so you react, I guess, a little bit more? [00:38:42] Natacha Chough: Yeah, so we -- that's something we don't totally understand yet. And even on earth, the immune -- immunology is one of the least understood medical specialties out there. Things are always changing. [00:38:53] Host: See, I don't understand why I get a flu shot sometimes, and then a month later I get the flu! [Laughter] I don't understand. I should be completely protected! And I know there's, like, you know, changes in strands or something. So, anyway, but, yeah, no, a lot of different things to -- to think about, I guess, from -- from your end, especially just -- that's a totally different world. Are you -- are you measuring some of these things over -- over time? And then understanding trends? Like, are there certain trends that you've seen just from studying astronauts in space for so long? [00:39:26] Natacha Chough: So we've got a group of epidemiologists, and then folks on the research side who are studying particular, you know, body systems, for example, like you're in chemistry or whatnot, those are the ones who are typically measuring those types of trends. [00:39:40] Host: Okay. [00:39:40] Natacha Chough: Yeah. And so anything that goes into our electronic medical record, we can have the epidemiologists look at and they can, you know, identify trends and they can control for changes in like the CAT scan machine that was used from this mission to this mission, and control for age or gender or whatnot, and so it's a lot of number crunching and, you know, doing statistics and making sure that any trends or changes that we're seeing are statistically significant. [00:40:05] Host: Okay, yeah. Because I know, like, you know, just understanding, like just basic, when you go to space, this is something that happens sort of things. Right? So your immune system gets a little bit weaker, your -- your muscles and bones start to, you know, get a little bit weaker and disappear so you have to build it back up and do this exercise all the time. Just medical things that you have to think about, you know, the human body, how it reacts to space. And these are things, these are lessons that we can take to missions beyond low-earth orbit too, right, to -- to station, our past station to, you know, the moon, deep space, Mars, all of that stuff. So how is the role of a flight surgeon going to change as we -- as the communication starts to get a little bit, you know, longer. Because when we go out to Mars, you're talking about when earth and Mars are at their farthest point away from each other, that's like a 40-something minute round trip for communication. [00:41:01] Natacha Chough: Yeah. Yeah, so, and the question is, right, like, do you then have a requirement to have a doctor onboard? And not only that, but what if the doctor is the one who is sick and becomes the patient, then what? Right? Because when you fly in an aircraft, you've got a pilot and a co-pilot, but if you've only got one doctor, I don't know, like, is it enough for someone else to, you know, be trained as a mid-level provider, like a physician assistant or a nurse practitioner or is it enough to have just in time, like on-orbit, you know, refresher training videos for a non-physician to be able to do a medical procedure? Do we need, you know, minimally-invasive surgery type capabilities on these spacecrafts? And those are all questions that, like I said, people way smarter than me are -- are looking into and challenges that we still need to address. [00:41:51] Host: Wow. Yeah, because there's -- there's a lot of different considerations. We just did a podcast pretty recently with Orion, and they were talking about just, like, for example, oxygen or something, right, like oxygen is super important to have on the spacecraft, but you can only put so many oxygen generators on the spacecraft before it becomes a little bit, okay, let's -- let's calm down. You know, because you have backups, but you can't just make -- keep making backups until you're perfectly fine. So the same with the physician's, right? You can't just have, like, an army of doctors going to space because, you know, it's just you need those other things, right, you can have a doctor, but then you need -- if you're doing Mars exploration, maybe a geologist, maybe an engineer, maybe a pilot, you know, you need all of the above, nice like diverse group of -- of astronauts who can do -- do it all in the -- in one mission. [00:42:40] Natacha Chough: Yeah, and I think also the -- the crew psychology is going to change a little bit. [00:42:45] Host: Oh yeah. [00:42:46] Natacha Chough: And so, you know, people have talked about, what's the ideal crew make up? Should they all be all one gender, should they have an even number versus an odd number? Because if you have an even number and you have a disagreement and you vote on something, what do you do if you have a tie? But if you have an odd number of crew members and there's one person who's the tiebreaker, are they then sort of, you know, like labeled as... [00:43:08] Host: Yeah. [00:43:09] Natacha Chough: You know? [00:43:09] Host: She's inside [inaudible] that guy or something. [00:43:11] Natacha Chough: And then there's questions about what kind of -- what degree of assertiveness or leadership do you want your commander versus someone who fosters more equality in community in a multi month, like, transit phase from earth to Mars, where there's not a lot going on, so do you really want somebody who's like super dominant on you all the time about something... [00:43:31] Host: Yeah. [00:43:31] Natacha Chough: ...when there's not a lot of operational things happening. [00:43:35] Host: Yeah. [00:43:35] Natacha Chough: Yeah, so a lot of -- a lot of factors there are going to be in play, but I think crew psychology and wellness is going to be huge. [00:43:43] Host: Oh yeah. I would assume that whatever crew they choose to do these deep space missions, they're going to be, you know, be able to do it all in a sense. They'll be super qualified people that have multiple disciplines, and when with the most recent astronaut class, that's reflected there too. You've got doctors with flight time, you've got Navy Seals slash doctor, you have, to know, an engineer in four different disciplines, so, you know, you got all of these people that can -- that can do it all. It's pretty cool. [Laughing] I guess from a flight surgeon perspective, you'd probably go more towards the -- the redundancy in doctor ability, like a doctor and then someone trained mid-level with the doctor, physician? [00:44:26] Natacha Chough: Potentially. Yeah, I mean, I guess I haven't really thought about it too much. I was just kind of like throwing out ideas, but [laughter], I mean, it's always good, you know, to have backups and potentially backups to your backup, so. [00:44:38] Host: So how about whenever, I mean, you know, we're going -- we're going out, way out into space, but I'm going to pull back for just a second. Like, your first -- your first time going out over to overseas, to support like a crew thing. I'm only asking -- I'm asking this selfishly because I'm about to go over to Kazakhstan myself. So what was -- what was that like, that experience of -- of, you know, working with the crew before a launch or after a landing or your first time? [00:45:05] Natacha Chough: So it actually felt very natural to me, and I think part of the reason is because I was a Peace Corp volunteer like before I went to medical school, and I was -- I lived in that region of the world. So I was doing service in Turkmenistan, and so to be in Kazakhstan was almost like coming home. So I felt very comfortable and part of that experience really turned me onto the International Space Station program because of the international cooperation part of it. So going over there was actually really fun for me, I really enjoyed it. And as to like the actual pre-launch experience, so as the deputy crew surgeon, for my first mission, your job is to take care of the family and launch guests that are invited. And so, you know, some folks aren't frequent international travelers, and Kazakhstan is fairly remote, so, you know, if you've got medical conditions, you know, I was trying to remind people to bring all their prescription meds that they're going to need, because we don't always necessarily have what they're going to need. We do carry a small medical pack with us with some like sleep meds and, you know, allergy meds, that type of thing, in case it's needed. [00:46:13] And then really it's just getting to know them, getting to make sure that your prime surgeon who's locked in quarantine has everything they need. If not, you know, we can arrange to -- to have extra supplies brought into them, you know, medically, if -- if they need something. And then the day of launch, depending on what time you launch, this may happen earlier or later, but I got up super early with our, you always have a nurse with you when you're going out into the field, and so we had the search and rescue forces pick us up in a van, and we went to the remote airport where their helicopter was staged to stay on the helicopter and wait for launch, and then once we got word that the crew had reached orbit, then the helicopter blade stops spinning and then we just go back to the hotel. So I -- on an ideal day, on launch, you're actually not doing too much, because things are working as they should. [00:47:08] Host: Right. Because your job is to be there, like, the helicopter blade spinning is the perfect analogy to, you know, if something goes wrong, you're getting in the helicopter. Right? That is your job. Otherwise, the blade stops spinning. So, that's exactly, cool. Wow, alright, a lot of -- a lot of cool stuff to do as a flight surgeon. Is there anything I missed about flight surgery, because a lot of this is very foreign to me because I, you know, medical stuff goes like right over my head [laughing], but I try -- I try to do my best to kind of summarize everything into something that's, you know, that we can tell out to the world and that makes a lot of sense and kind of encapsulates the story of astronaut health. [00:47:50] Natacha Chough: Oh, so there was one thing I was going to say. So, and this is kind of like a misconception that I think is important to clear up for folks out there who are interested in becoming a flight surgeon or who are in medical school. [00:48:00] Host: Yeah. [00:48:01] Natacha Chough: So, some flight surgeons have gone on to become astronauts, and subsequently flown in space, but they're in the minority. So being a flight surgeon is not a shortcut to becoming an astronaut, I'm sorry if I'm crushing any dreams out there, but we get to do a lot of what an astronaut does, except fly in space. So we're with them for a lot of the training they do, and, you know, while space is, no doubt, the best part of being an astronaut, it's a pretty small percentage of their career, so, like, I don't feel too bad about my job, I actually love my job, and it's -- there's another doc in our group who refers to it as being like, taking care of Lewis and Clark. And so I think that's totally appropriate and it's super rewarding. We are one of the first faces they see, you know, on landing. So if you see the -- the PAO shots of the crew getting pulled out of the Soyuz, we're like the, you know, the other person in the blue flight suit in the corner [laughing], making sure they're okay along with our -- we've got great Russian field medical nurses that help us out with taking vitals and all of that, so. [00:48:58] Host: That's right. You're there for every step of the way, except on the International Space Station. [00:49:02] Natacha Chough: That is okay. [00:49:03] Host: Yeah, that's -- oh, really, you wouldn't want to -- you wouldn't want to fly? [00:49:07] Natacha Chough: Oh, no, I just mean, you know, this job is so rewarding for me as is that I'm happy as a clam. [00:49:13] Host: Hey, yeah, you can't complain, because you're doing -- you're doing some really, really cool stuff. That's really awesome. Yeah, well if you -- if you do, you know, want to be a flight surgeon slash astronaut, there -- is it -- is it Kell Lindgren [phonetic]? [00:49:26] Natacha Chough: Kjell. [00:49:26] Host: Kjell Lindgren, yeah, Kjell Lindgren was a flight surgeon turned astronaut, right? [00:49:31] Natacha Chough: And Mike Beret, Tom Marshburn, and then Serena Aunon-Chancellor [phonetic] next year. [00:49:36] Host: What? Oh, all of them? [00:49:37] Natacha Chough: They were all previously flight surgeons. [00:49:39] Host: Ahhh, so you say it's low, but there's quite a few [laughter], there's quite a few! And, you know, definitely a medical doctor, I think, would be up there for someone who's essential on a deep space mission. I definitely think, you know, for missions beyond, they're going to be -- they're going to be up there. Because the human body is like -- it's one of the things we're focusing on when we're doing studies on the International Space Station, right? Like, studies on the human body, but then it's going to be a huge factor for missions beyond, because there's different things you have to worry about. [00:50:09] Natacha Chough: And we're the most annoying variable, I would say, right? Like, to -- to an engineer's who's focused on, you know, the spacecraft and things being like within binary ranges, we have the most variables within our physiologic system to -- to have the potential to drive folks crazy. So sometimes we'll get questions, you know, like, well, what's, you know, how low can this temperature be, or whatever, like, well, it depends. It depends on, you know, [laughing] all these different factors. And so I know that's -- that's hard to hear sometimes. So, you know, we have to -- to bound the question appropriately and then, you know, start from a place that's, you know, medically, ethically, you know, safe for the crew, and then that's your starting point to -- to work from there. [00:50:51] Host: Yeah. Yeah, and it's just -- it's got to be so cool just working with an astronaut throughout the whole thing. Have you ever done the 0 gravity flight? [00:50:58] Natacha Chough: Yes! Yep, that's part of our training as well. [00:51:00] Host: Alright! So that's -- so that's pretty close to space, right? [00:51:03] Natacha Chough: Yeah. [00:51:03] Host: You kind of feel the microgravity. [00:51:06] Natacha Chough: It's for 30 -- about 30 seconds at a time. Yeah, it's pretty much exactly how I imagined it like in my dreams as a kid. It was actually super fun, and it's -- it felt like Christmas [laughing]. That's like the best way I can describe it. [00:51:18] Host: Wow. Did you -- were you there as a flight surgeon like with an astronaut, or were you there for something else? [00:51:24] Natacha Chough: I was there as like an aerospace medicine resident in training. It was sort of just like an exposure flight for me. [00:51:31] Host: Yeah [laughing]. [00:51:31] Natacha Chough: It was super fun! [00:51:33] Host: Alright. Something definitely cool to get exposed to, right? That's like a once-in-a-lifetime kind of thing. That's pretty cool. [00:51:40] Natacha Chough: I'll take that over the, you know, losing brain cells in the hypoxia chamber [laughter]. [00:51:43] Host: Yeah! Unfortunately, that's something you've done multiple times. Multiple 0 gravity flights would be pretty cool. Alright. Alright, well, Natacha, thanks so much for coming on the show. I think this was a nice -- nice overview of what a flight surgeon does and how it helps in, you know, every step of the way for Lewis and Clark, I love that analogy, that's perfect. So, thanks for coming on the show and talking about what a flight surgeon does. [00:52:03] Natacha Chough: Thanks for having me! [00:52:04] Host: Very cool. [00:52:05] [ Music ] [00:52:14] [ Music & Radio Transmissions ] Host: Hey! Thanks for sticking around. So today we talked with Dr. Natacha Chough about her role as a flight surgeon and what that has to do with astronaut health. If you want to know what's going on in the role of human research and how that applies to spaceflight, NASA,gov/hrp is a great resource for all of that. Everything human research and how that applies to spaceflight. If you go to NASA.gov/iss, you can figure out all the stuff going on on the International Space Station, and a lot of that has to do with some of the human research we're doing, as we talked about it in this episode. Otherwise, on social media, you can follow us Facebook, Twitter, Instagram, follow the International Space Station accounts, they're verified and, you know, we got a lot of followers, so you can find us pretty easily. But just use the hashtag, AskNASA, on any one of those platforms, if you want to ask a question about the show, and actually that's where I found the recommendation for this show, is actually on Twitter. [00:53:19] So, I'm paying attention to all of that, just make sure to mention it's for Houston, we have a podcast, and then -- and then we'll go from there! So, the credits for today go to John [inaudible] and Alex [inaudible]. Thanks again to Dr. Natacha Chough for coming on the show this week. This podcast was recorded on November 15th. We'll be back next week!

hwhap_Ep13_First Flight

NASA Image and Video Library

2017-10-06

. >> OH. >> SO, I WAS REALLY, REALLY SPEEDING UP AND I ONLY HAD TO CLIMB UP TO 3,000 FEET, WHICH YOU DO REALLY FAST IN THAT JET IF YOU HAVEN’T TAKEN THE POWER OUT. >> WHOA. >> AND SO, SAME THING, I GOT TO 3,000 FEET, I WAS CLIMBING REALLY, REALLY FAST, HE SAID, “CHECK YOUR ALTITUDE.” AND MY IMMEDIATE RESPONSE WASN’T TO TAKE OUT THE POWER, IT WAS JUST TO PITCH THE NOSE FORWARD, WHICH MEANT THAT ANYTHING THAT I HAD LOOSE IN THE JET JUST HIT THE CEILING BECAUSE I JUST WENT DOWN SO FAST ALL THE SUDDEN. >> WHOA. >> REALLY GOOD TRAINING. >> YEAH. >> I DIDN’T FORGET THAT LESSON. >> YEAH. THAT’S GOOD THAT YOU GUYS ARE ALWAYS KEEPING EACH OTHER IN CHECK. I’M SURE THAT ALL YOUR ASTRONAUT-- YOUR FELLOW ASTRONAUTS ARE CONSTANTLY DOING THIS, RIGHT? THEY’RE GIVING YOU ADVICE AND ANYTHING LIKE THAT. >> ABSOLUTELY. >> NOW, YOU BEING A FIRST TIME FLYER, I’M SURE THEY’VE GIVEN YOU SOME OF THOSE EXPERIENCES, ESPECIALLY SOME OF YOUR CLASSMATES, RIGHT? >> MM-HMM. >> SO WE HAVE REID WISEMAN, AND I’M TRYING TO THINK. >> MIKE HOPKINS. >> MIKE HOPKINS. >> KJELL LINDGREN. >> KJELL-- ALL THESE GUYS HAVE FLOWN BEFORE. >> KATE RUBINS. >> YEAH, THAT’S RIGHT, KATE MOST RECENTLY. SO, HAVE THESE GUYS GIVEN YOU SOME ADVICE, COME TO YOU AND SAY, “HEY, THIS”-- YOU KNOW, ANY KIND OF THINGS THAT YOU HAVE TO BE WATCHING OUT FOR? >> ABSOLUTELY. >> YEAH. >> AND NOT JUST THEM, ALL OF THEM. >> RIGHT. >> EVERYTHING FROM IF YOU’RE HAVING A BAD DAY DON’T TALK TO IT ON THE-- DON’T TALK TO PEOPLE ABOUT IT ON THE RADIO, TO EXPECTATIONS ON HOW TO-- AS YOU’RE GETTING READY FOR THE LAUNCH AND YOUR FAMILY’S IN KAZAKHSTAN, GETTING READY FOR THAT, WHAT TO EXPECT OUT OF THAT. >> ANY GOOD NUGGETS THAT THEY’VE TOLD YOU? >> CHRIS CASSIDY TOLD ME THAT ONE OF THE THINGS TO DO WHEN YOU’RE DOING A PROCEDURE IS TO MAKE SURE-- THERE’S NOTES BLOCKS IN A LOT OF THE PROCEDURES. >> MM-HMM. >> AND HE SAID, “THE NOTES BLOCKS AREN’T REQUIRED FOR US TO READ.” >> HMM. >> BUT, YOU REALLY NEED TO

HWHAP_Ep4_Space Food

NASA Image and Video Library

2017-07-28

them in a different environment? Takiyah Sirmons: Well, we're not growing plants at the food lab, a lot of that work is housed out of Kennedy Space Center in Florida. And so they are growing different dwarf vegetables with the expectation that that would supplement the foods system but not necessarily be the full menu. So we still have to have a standard menu that will provide the core amount of calories. And then there's a certain amount of food that you can grow to increase their variety. And so we've partnered with them on a couple of their projects, mainly for the sensory component so seeing whether or not those products taste good and whether or not consumers can tell the difference between a product that was grown in the greenhouse versus something that you would buy in the grocery store. And so we've done a little bit of work with them on that. Host: All right, all right that sounds awesome. Takiyah Sirmons: They can have a salad in space. Host: Yeah, cut up some fresh tomatoes or something. Takiyah Sirmons: They goes a long way, if they haven't had a salad in a while then you'd be very thrilled to have one in space. Host: That is true, they did something on International Space Station recently, right the veggie experiment. Some lettuce, Scott Kelly and Kjell Lindgren and some of those guys actually got to taste it up in orbit and they said it tasted like arugula. Takiyah Sirmons: Oh, okay, arugula is tasty. Host: So it would be good for a salad right, sprinkle a little arugula on a salad, I mean I'm imagining eggs benedict right now, I'm super hungry. Takiyah Sirmons: We're not there yet. Host: One, day, one day, oh okay all right so is there anything that you've learned you know, about astronauts, just anything new. I know taste buds maybe change but is there anything that they brought down with them from their experience on orbit that has kind of changed the way that. Or maybe not exactly changed the way but just added something to the way that you process

Ep8_Exploring the Cosmos with Styx

NASA Image and Video Library

2017-08-25

. >> THEY DO A BUNCH OF DIFFERENT THINGS. >> YEAH. >> FOR EXAMPLE, WOODY HOBURG IS AN ENGINEER IN FOUR DIFFERENT TYPES OF-- HE’S LIKE COMPUTER SCIENCE, AND ELECTRICAL, AND AEROSPACE, AND MECHANICAL. LIKE HE’S ALL OF THEM. AND THEN WHEN YOU’RE TALKING ABOUT A DOCTOR PILOT, FRANK RUBIO IS A DOCTOR PILOT. HE FLEW HELICOPTERS, AND THEN HE DID SOME SKYDIVING, BUT THEN ALSO IS A MEDICAL DOCTOR BY TRAINING. IT’S INSANE. SO, THEY’RE FINDING THESE FOLKS THAT HAVE ALL OF THESE DIFFERENT SPECIALITIES, BUT WHEN YOU’RE TALKING ABOUT SCIENTIST/MEDICAL DOCTOR/PILOT AND THEN YOU HAVE ALL OF THESE DIFFERENT FOLKS THAT ARE SLASH, SLASH, SLASH, IT’S AMAZING. I HAVE-- >> AND I WOULD RECOMMEND HAVING-- BEING ABLE TO PLAY AN INSTRUMENT. >> AND MANY ASTRONAUTS KNOW HOW TO. >> RIGHT. >> YEAH. >> WE HAVE GUITARS AND OTHER THINGS UP IN SPACE RIGHT NOW. >> YEAH. >> BECAUSE MUSIC IS REALLY A PART OF LIFE. >> ABSOLUTELY. >> AND IT’S ONE THING TO HAVE PRE-RECORDED MUSIC, BUT TO CREATE MUSIC AND MAKE YOUR OWN MUSIC WOULD BE PART OF IT. BECAUSE YOU NEED JOY. >> YEAH. ABSOLUTELY. >> YOU CAN’T DO-- NOT JUST WORKING ALL THE TIME. YOU NEED TO HAVE THE JOY OF LIFE. >> AND YOU’RE RIGHT, SOME OF THE-- SO, RIGHT, AS WE WERE SAYING, WE HAVE PROGRESSED FROM SHUTTLE FLIGHTS, WHICH WERE A COUPLE OF DAYS, ALL THE WAY UP TO NOW INTERNATIONAL SPACE STATION FLIGHTS, WHICH ARE SEVERAL MONTHS. >> YEAH. >> SO, THEY’RE UP THERE FOR A LONG TIME AND A LOT OF THEM, LIKE YOU SAY, THEY DO BRING INSTRUMENTS. >> YEAH, CHRIS HADFIELD. >> WE HAVE-- CHRIS HADFIELD HAS HIS GUITAR, RIGHT? >> HE’S GREAT. >> HE’S JAMMIN’. WE’VE HAD FOLKS BRING FLUTES. >> CADY COLEMAN. >> CADY COLEMAN, RIGHT. AND THEN I THINK KJELL LINDGREN BROUGHT BAGPIPES, RIGHT? >> WOW! >> THEY MADE HIM PRACTICE WAY ON THE OTHER SIDE. >> YEAH! >> HE WASN’T INVITED BACK! >> YOU KNOW WHAT, IT’S FUNNY. YEAH, I THINK SIX IS A GOOD NUMBER. THERE’S SIX MEMBERS OF STYX AS WELL, AND WE ARE VERY GOOD AT THE MUSIC PART. >> WE DO HAVE A