Science.gov

Sample records for 64-row dual source

  1. Multidetector-row CT with a 64-row amorphous silicon flat panel detector

    NASA Astrophysics Data System (ADS)

    Shapiro, Edward G.; Colbeth, Richard E.; Daley, Earl T.; Job, Isaias D.; Mollov, Ivan P.; Mollov, Todor I.; Pavkovich, John M.; Roos, Pieter G.; Star-Lack, Josh M.; Tognina, Carlo A.

    2007-03-01

    A unique 64-row flat panel (FP) detector has been developed for sub-second multidetector-row CT (MDCT). The intent was to explore the image quality achievable with relatively inexpensive amorphous silicon (a-Si) compared to existing diagnostic scanners with discrete crystalline diode detectors. The FP MDCT system is a bench-top design that consists of three FP modules. Each module uses a 30 cm x 3.3 cm a-Si array with 576 x 64 photodiodes. The photodiodes are 0.52 mm x 0.52 mm, which allows for about twice the spatial resolution of most commercial MDCT scanners. The modules are arranged in an overlapping geometry, which is sufficient to provide a full-fan 48 cm diameter scan. Scans were obtained with various detachable scintillators, e.g. ceramic Gd IIO IIS, particle-in-binder Gd IIO IIS:Tb and columnar CsI:Tl. Scan quality was evaluated with a Catphan-500 performance phantom and anthropomorphic phantoms. The FP MDCT scans demonstrate nearly equivalent performance scans to a commercial 16-slice MDCT scanner at comparable 10 - 20 mGy/100mAs doses. Thus far, a high contrast resolution of 15 lp/cm and a low contrast resolution of 5 mm @ 0.3 % have been achieved on 1 second scans. Sub-second scans have been achieved with partial rotations. Since the future direction of MDCT appears to be in acquiring single organ coverage per scan, future efforts are planned for increasing the number of detector rows beyond the current 64- rows.

  2. Dual source heat pump

    DOEpatents

    Ecker, Amir L.; Pietsch, Joseph A.

    1982-01-01

    What is disclosed is a heat pump apparatus for conditioning a fluid characterized by a fluid handler and path for circulating the fluid in heat exchange relationship with a refrigerant fluid; at least two refrigerant heat exchangers, one for effecting heat exchange with the fluid and a second for effecting heat exchange between refrigerant and a heat exchange fluid and the ambient air; a compressor for efficiently compressing the refrigerant; at least one throttling valve for throttling liquid refrigerant; a refrigerant circuit; refrigerant; a source of heat exchange fluid; heat exchange fluid circulating device and heat exchange fluid circuit for circulating the heat exchange fluid in heat exchange relationship with the refrigerant; and valves or switches for selecting the heat exchangers and direction of flow of the refrigerant therethrough for selecting a particular mode of operation. The heat exchange fluid provides energy for defrosting the second heat exchanger when operating in the air source mode and also provides a alternate source of heat.

  3. Comparison of Reconstruction Intervals in Routine ECG-Pulsed 64-Row-MSCT Coronary Angiography in Frequency Controlled Patients

    SciTech Connect

    Frydrychowicz, Alex Pache, Gregor; Saueressig, Ulrich; Foell, Daniela; Kotter, Elmar; Langer, Mathias; Bley, Thorsten A.

    2007-02-15

    Purpose. In light of the increasing use and acceptance of multislice computed tomography (MSCT) coronary angiography it was the purpose of this study to compare reconstruction intervals used in a routine ECG-pulsed MSCT coronary artery angiography setting with frequency controlled patients. Methods. Examinations were performed on a Siemens Somatom Sensation 64 scanner with a total of 110 ml of contrast agent and ECG pulsing (interval from 40% to 70%) after oral application of a {beta}-blocker if the heart rate was higher than 65 bpm. All human subjects were referred for the evaluation of suspected coronary artery disease. Coronary artery segments were evaluated by two experienced radiologists in a consensus reading. A ranking of diagnostic image quality (from 1 (no evaluation possible) to 5 (excellent image quality)) was statistically evaluated by Wilcoxon Signed Rank Test. Results. In 45 patients (30 male, 15 female, age 63.8 {+-} 12.1 years) we detected a significant advantage of the 60% reconstruction interval over 40%, 50%, and 70% (for each p < 0.05). In cases of sudden arrhythmia or movement during the scan, additional reconstruction intervals within the ECG-pulsed reconstruction intervals remained necessary for diagnosis. Conclusion. In a routine diagnostic setting with frequency controlled patients and ECG pulsing the 60% reconstruction interval can be considered superior for the initial diagnosis in 64-row multislice computed tomography coronary angiography. However, further information can be derived from various reconstruction intervals such as 40% and 70%.

  4. Exploiting dual otoacoustic emission sources

    NASA Astrophysics Data System (ADS)

    Abdala, Carolina; Kalluri, Radha

    2015-12-01

    Two distinct processes generate otoacoustic emissions (OAEs). Reflection-source emissions, here recorded as stimulus frequency OAEs, are optimally informative at low sound levels and are more sensitive to slight hearing loss; they have been linked to cochlear amplifier gain and tuning. Distortion-source emissions are strongest at moderate-high sound levels and persist despite mild hearing loss; they likely originate in the nonlinear process of hair cell transduction. In this preliminary study, we exploit the unique features of each by generating a combined reflection-distortion OAE profile in normal hearing and hearing-impaired ears. Distortion-product (DP) and stimulus-frequency (SF) OAEs were recorded over a broad range of stimulus levels and frequencies. Individual I/O and transfer functions were generated for both emission types in each ear, and OAE peak strength, compression threshold, and rate of compression were calculated. These combined SFOAE and DPOAE features in normal and hearing-impaired ears may provide a potentially informative and novel index of hearing loss. This is an initial step toward utilizing OAE source in characterizing cochlear function and dysfunction.

  5. Dual energy with dual source CT and kVp switching with single source CT: a comparison of dual energy performance

    NASA Astrophysics Data System (ADS)

    Grasruck, M.; Kappler, S.; Reinwand, M.; Stierstorfer, K.

    2009-02-01

    Stimulated by the introduction of clinical dual source CT, the interest in dual energy methods has been increasing in the past years. Whereas the potential of material decomposition by dual energy methods is known since the early 1980ies, the realization of dual energy methods is a wide field of today's research. Energy separation can be achieved with energy selective detectors or by varying X-ray source spectra. This paper focuses on dual energy techniques with varying X-ray spectra. These can be provided by dual source CT devices, operated with different kVp settings on each tube. Excellent spectral separation is the key property for use in clinical routine. The drawback of higher cost for two tubes and two detectors leads to an alternative realization, where a single source CT yields different spectra by fast kVp switching from reading to reading. This provides access to dual-energy methods in single source CT. However, this technique comes with some intrinsic limitations. The maximum X-ray flux is reduced in comparison to the dual source system. The kVp rise and fall time between each reading reduces the spectral separation. In comparison to dual source CT, for a constant number of projections per energy spectrum the temporal resolution is reduced; a reasonable trade of between reduced numbers of projection and limited temporal resolution has to be found. The overall dual energy performance is the guiding line for our investigations. We present simulations and measurements which benchmark both solutions in terms of spectral behavior, especially of spectral separation.

  6. Dual-Cathode Electron-Beam Source

    NASA Technical Reports Server (NTRS)

    Bradley, James G.; Conley, Joseph M.; Wittry, David B.

    1988-01-01

    Beam from either cathode electromagnetically aligned with exit port. Electron beam from either of two cathodes deflected by magnetic and electric fields to central axis. Mechanical alignment of beam easy because cathode axes, anode apertures, and electron trajectories coplanar. Applications where uninterrupted service needed: scanning electron microscopes, transmission electron microscopes, electron-beam lithography equipment, Auger instruments, and microfocused x-ray sources.

  7. The HelCat dual-source plasma device.

    PubMed

    Lynn, Alan G; Gilmore, Mark; Watts, Christopher; Herrea, Janis; Kelly, Ralph; Will, Steve; Xie, Shuangwei; Yan, Lincan; Zhang, Yue

    2009-10-01

    The HelCat (Helicon-Cathode) device has been constructed to support a broad range of basic plasma science experiments relevant to the areas of solar physics, laboratory astrophysics, plasma nonlinear dynamics, and turbulence. These research topics require a relatively large plasma source capable of operating over a broad region of parameter space with a plasma duration up to at least several milliseconds. To achieve these parameters a novel dual-source system was developed utilizing both helicon and thermionic cathode sources. Plasma parameters of n(e) approximately 0.5-50 x 10(18) m(-3) and T(e) approximately 3-12 eV allow access to a wide range of collisionalities important to the research. The HelCat device and initial characterization of plasma behavior during dual-source operation are described.

  8. Dual radio frequency plasma source: Understanding via electrical asymmetry effect

    SciTech Connect

    Bora, B.; Bhuyan, H.; Favre, M.; Wyndham, E.; Wong, C. S.

    2013-04-21

    On the basis of the global model, the influences of driving voltage and frequency on electron heating in geometrically symmetrical dual capacitively coupled radio frequency plasma have been investigated. Consistent with the experimental and simulation results, non-monotonic behavior of dc self bias and plasma heating with increasing high frequency is observed. In addition to the local maxima of plasma parameters for the integer values of the ratio between the frequencies ({xi}), ourstudies also predict local maxima for odd integer values of 2{xi} as a consequence of the electrical asymmetry effect produced by dual frequency voltage sources.

  9. Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy.

    PubMed

    Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

    2014-02-07

    Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source-dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10-15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source-dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented.

  10. Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

    2014-02-01

    Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source-dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10-15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source-dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented.

  11. Dual-source CT for chest pain assessment

    PubMed Central

    Nikolaou, Konstantin; Becker, Alexander; Leber, Alexander W.; Rist, Carsten; Wintersperger, Bernd J.; Reiser, Maximilian F.; Becker, Christoph R.

    2007-01-01

    Comprehensive CT angiography protocols offering a simultaneous evaluation of pulmonary embolism, coronary stenoses and aortic disease are gaining attractiveness with recent CT technology. The aim of this study was to assess the diagnostic accuracy of a specific dual-source CT protocol for chest pain assessment. One hundred nine patients suffering from acute chest pain were examined on a dual-source CT scanner with ECG gating at a temporal resolution of 83 ms using a body-weight-adapted contrast material injection regimen. The images were evaluated for the cause of chest pain, and the coronary findings were correlated to invasive coronary angiography in 29 patients (27%). The files of patients with negative CT examinations were reviewed for further diagnoses. Technical limitations were insufficient contrast opacification in six and artifacts from respiration in three patients. The most frequent diagnoses were coronary stenoses, valvular and myocardial disease, pulmonary embolism, aortic aneurysm and dissection. Overall sensitivity for the identification of the cause of chest pain was 98%. Correlation to invasive coronary angiography showed 100% sensitivity and negative predictive value for coronary stenoses. Dual-source CT offers a comprehensive, robust and fast chest pain assessment. PMID:18034246

  12. Dual mode-locked swept sources for SS-OCT

    NASA Astrophysics Data System (ADS)

    Stancu, Radu F.; Podoleanu, Adrian G.

    2016-03-01

    A novel dual-mode-locking mechanism was developed in order to tune an akinetic swept source (AKSS) based on dispersive cavity at a repetition rate close to, but slightly different from the inverse of the cavity roundtrip. Several optical source configurations emitting in the 1060 nm or 1550 nm wavelength region were developed, characterized and tested in OCT applications. For the 1550 nm swept source employing a Faraday rotating mirror in a dispersive cavity, sweeping rates in the range of MHz were achieved, from 782 kHz to up to 5 times this value, with proportional decrease in the tuning bandwidth. Linewidths smaller than 60 pm and output powers exceeding a few mW were measured. The 1060 nm swept source implemented was used to generate OCT images of a pressure sensitive adhesive.

  13. A millimeter wavelength radiation source using a dual grating resonator

    SciTech Connect

    Killoran, J.H.; Hacker, F.L.; Walsh, J.E. . Dept. of Physics)

    1994-10-01

    A novel means of producing coherent radiation by passing an electron through a dual-grating resonator is presented. The observed radiation is in accordance with the Smith-Purcell dispersion relation for a single grating. Feedback is provided by a second grating. Experiments carried out at beam energies from 30--55 KeV produced radiation at wavelengths from 6 to 0.75 mm. Power measurements were used to clarify the grating-beam interaction. Indications are that operation could be easily extended to shorter wavelengths to provide an inexpensive and compact radiation source in the far-infrared.

  14. Quantitative imaging of chemical composition using dual-energy, dual-source CT

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Primak, Andrew N.; Yu, Lifeng; McCollough, Cynthia H.; Morin, Richard L.

    2008-03-01

    Dual-energy x-ray material decomposition has been proposed as a noninvasive quantitative imaging technique for more than 20 years. In this paper, we summarize previously developed dual-energy material decomposition methods and propose a simple yet accurate method for quantitatively measuring chemical composition in vivo. In order to take advantage of the newly developed dual-source CT, the proposed method is based upon post reconstruction (image space) data. Different from other post reconstruction methods, this method is designed to directly measure element composition (mass fraction) in a tissue by a simple table lookup procedure. The method has been tested in phantom studies and also applied to a clinical case. The results showed that this method is capable of accurately measuring elemental concentrations, such as iron in tissue, under low noise imaging conditions. The advantage of this method lies in its simplicity and fast processing times. We believe that this method can be applied clinically to measure the mass fraction of any chemical element in a two-material object, such as to quantify the iron overload in the liver (hemochromatosis). Further investigations on de-noising techniques, as well as clinical validation, are merited.

  15. Vertical-dual-source tunnel FETs with steeper subthreshold swing

    NASA Astrophysics Data System (ADS)

    Zhi, Jiang; Yiqi, Zhuang; Cong, Li; Ping, Wang; Yuqi, Liu

    2016-09-01

    In order to improve the drive current and subthreshold swing (SS), a novel vertical-dual-source tunneling field-effect transistor (VDSTFET) device is proposed in this paper. The influence of source height, channel length and channel thickness on the device are investigated through two-dimensional numerical simulations. Si-VDSTFET have greater tunneling area and thinner channel, showing an on-current as high as 1.24 μA at gate voltage of 0.8 V and drain voltage of 0.5 V, off-current of less than 0.1 fA, an improved average subthreshold swing of 14 mV/dec, and a minimum point slope of 4 mV/dec. Project supported by the National Natural Science Foundation of China (Nos. 61204092, 61574109).

  16. Dual-Frequency Coherence of Seismic Tremor and Source Properties

    NASA Astrophysics Data System (ADS)

    Dorman, L. M.; Schwartz, S. Y.; Clarke, D. L.

    2009-12-01

    Last fall Dorman and Schwartz reported discovery of a statistical signature (Dual-frequency coherence-DFC) which distinguishes nonvolcanic tremor from the usual microseismic noise. This was first observed in OBS data from the CRSEIZE experiment of 1999-2000 (DeShon and others, 2006), and later on land data from the Nicoya Peninsula. The tremor observed on OBSs was correlated with fluid flow through the seafloor (Brown and others, 2005). The observation of this signature on both land and OBS data indicates that it is a property of the source, rather than the path or the instrument or its environment. Possible causes include the fluid flow noise proposed by Julian (1994) and a repetitive stick-slip motion. Recent work has shown that nonvolcanic tremor accompanying slow slip in three different subduction zones, including northern Costa Rica, consists of swarms of low-frequency earthquakes that occur as stick-slip motion on the plate interface (Brown et al., 2008). Thus, both fluid flow and shear failure sources may be responsible for tremor generation. New work reveals that a Rössler attractor of the type studied by Julian produces a DFC similar to that of the tremor. Since the frequency of the oscillator is controlled by the physical properties of the source (fluid viscosity, channel dimension, flow velocity) this establishes a link between the seismically observable offset frequencies and one potential source mechanism.

  17. Dual-source dual-power electrospinning and characteristics of multifunctional scaffolds for bone tissue engineering.

    PubMed

    Wang, Chong; Wang, Min

    2012-10-01

    Electrospun tissue engineering scaffolds are attractive due to their distinctive advantages over other types of scaffolds. As both osteoinductivity and osteoconductivity play crucial roles in bone tissue engineering, scaffolds possessing both properties are desirable. In this investigation, novel bicomponent scaffolds were constructed via dual-source dual-power electrospinning (DSDPES). One scaffold component was emulsion electrospun poly(D,L-lactic acid) (PDLLA) nanofibers containing recombinant human bone morphogenetic protein (rhBMP-2), and the other scaffold component was electrospun calcium phosphate (Ca-P) particle/poly(lactic-co-glycolic acid) (PLGA) nanocomposite fibers. The mass ratio of rhBMP-2/PDLLA fibers to Ca-P/PLGA fibers in bicomponent scaffolds could be controlled in the DSDPES process by adjusting the number of syringes used to supply solutions for electrospinning. Through process optimization, both types of fibers could be evenly distributed in bicomponent scaffolds. The structure and properties of each type of fibers in the scaffolds were studied. The morphological and structural properties and wettability of scaffolds were assessed. The effects of emulsion composition for rhBMP-2/PDLLA fibers and mass ratio of fibrous components in bicomponent scaffolds on in vitro release of rhBMP-2 from scaffolds were investigated. In vitro degradation of scaffolds was also studied by monitoring their morphological changes, weight losses and decreases in average molecular weight of fiber matrix polymers.

  18. Dual energy CT with photon counting and dual source systems: comparative evaluation

    NASA Astrophysics Data System (ADS)

    Atak, Haluk; Shikhaliev, Polad M.

    2015-12-01

    Recently, new dual energy (DE) computed tomography (CT) systems—dual source CT (DSCT) and photon counting CT (PCCT) have been introduced. Although these systems have the same clinical targets, they have major differences as they use dual and single kVp acquisitions and different x-ray detection and energy resolution concepts. The purpose of this study was theoretical and experimental comparisons of DSCT and PCCT. The DSCT Siemens Somatom Flash was modeled for simulation study. The PCCT had the same configuration as DSCT except it used a photon counting detector. The soft tissue phantoms with 20, 30, and 38 cm diameters included iodine, CaCO3, adipose, and water samples. The dose (air kerma) was 14 mGy for all studies. The low and high energy CT data were simulated at 80 kVp and 140 kVp for DSCT, and in 20-58 keV and 59-120 keV energy ranges for PCCT, respectively. The experiments used Somatom Flash DSCT system and PCCT system based on photon counting CdZnTe detector with 2  ×  256 pixel configuration and 1  ×  1 mm2 pixels size. In simulated general CT images, PCCT provided higher contrast-to-noise ratio (CNR) than DSCT with 0.4/0.8 mm Sn filters. The PCCT with K-edge filter provided higher CNR than the PCCT with a Cu filter, and DSCT with 0.4 mm Sn filter provided higher CNR than the DSCT with a 0.8 mm Sn filter. In simulated DE subtracted images, CNR of the DSCT was comparable to the PCCT with a Cu filter. However, DE PCCT with Ho a K-edge filter provided 30-40% higher CNR than the DE DSCT with 0.4/0.8 mm Sn filters. The experimental PCCT provided higher CNR in general imaging compared to the DSCT. In experimental DE subtracted images, the DSCT provided higher CNR than the PCCT with a Cu filter. However, experimental CNR with DE PCCT with K-edge filter was 15% higher than in DE DSCT, which is less than 30-40% increase predicted by the simulation study. It is concluded that ideal PCCT can provide substantial advantages over ideal

  19. Temporal resolution and motion artifacts in single-source and dual-source cardiac CT

    SciTech Connect

    Schoendube, Harald; Allmendinger, Thomas; Stierstorfer, Karl; Bruder, Herbert; Flohr, Thomas

    2013-03-15

    Purpose: The temporal resolution of a given image in cardiac computed tomography (CT) has so far mostly been determined from the amount of CT data employed for the reconstruction of that image. The purpose of this paper is to examine the applicability of such measures to the newly introduced modality of dual-source CT as well as to methods aiming to provide improved temporal resolution by means of an advanced image reconstruction algorithm. Methods: To provide a solid base for the examinations described in this paper, an extensive review of temporal resolution in conventional single-source CT is given first. Two different measures for assessing temporal resolution with respect to the amount of data involved are introduced, namely, either taking the full width at half maximum of the respective data weighting function (FWHM-TR) or the total width of the weighting function (total TR) as a base of the assessment. Image reconstruction using both a direct fan-beam filtered backprojection with Parker weighting as well as using a parallel-beam rebinning step are considered. The theory of assessing temporal resolution by means of the data involved is then extended to dual-source CT. Finally, three different advanced iterative reconstruction methods that all use the same input data are compared with respect to the resulting motion artifact level. For brevity and simplicity, the examinations are limited to two-dimensional data acquisition and reconstruction. However, all results and conclusions presented in this paper are also directly applicable to both circular and helical cone-beam CT. Results: While the concept of total TR can directly be applied to dual-source CT, the definition of the FWHM of a weighting function needs to be slightly extended to be applicable to this modality. The three different advanced iterative reconstruction methods examined in this paper result in significantly different images with respect to their motion artifact level, despite exactly the same

  20. DualSPHysics: Open-source parallel CFD solver based on Smoothed Particle Hydrodynamics (SPH)

    NASA Astrophysics Data System (ADS)

    Crespo, A. J. C.; Domínguez, J. M.; Rogers, B. D.; Gómez-Gesteira, M.; Longshaw, S.; Canelas, R.; Vacondio, R.; Barreiro, A.; García-Feal, O.

    2015-02-01

    DualSPHysics is a hardware accelerated Smoothed Particle Hydrodynamics code developed to solve free-surface flow problems. DualSPHysics is an open-source code developed and released under the terms of GNU General Public License (GPLv3). Along with the source code, a complete documentation that makes easy the compilation and execution of the source files is also distributed. The code has been shown to be efficient and reliable. The parallel power computing of Graphics Computing Units (GPUs) is used to accelerate DualSPHysics by up to two orders of magnitude compared to the performance of the serial version.

  1. Precision error in dual-photon absorptiometry related to source age

    SciTech Connect

    Ross, P.D.; Wasnich, R.D.; Vogel, J.M.

    1988-02-01

    An average, variable precision error of up to 6% related to source age was observed for dual-photon absorptiometry of the spine in a longitudinal study of bone mineral content involving 393 women. Application of a software correction for source decay compensated for only a portion of this error. The authors conclude that measurement of bone-loss rates using serial dual-photon bone mineral measurements must be interpreted with caution.

  2. Left Ventricular Diastolic Dysfunction Assessment with Dual-Source CT

    PubMed Central

    Wen, Zhaoying; Ma, Heng; Zhao, Ying; Fan, Zhanming; Zhang, Zhaoqi; Choi, Sang Il; Choe, Yeon Hyeon; Liu, Jiayi

    2015-01-01

    Purpose To assess the impact of left ventricular (LV) diastolic dysfunction on left atrial (LA) phasic volume and function using dual-source CT (DSCT) and to find a viable alternative prognostic parameter of CT for LV diastolic dysfunction through quantitative evaluation of LA phasic volume and function in patients with LV diastolic dysfunction. Materials and Methods Seventy-seven patients were examined using DSCT and Doppler echocardiography on the same day. Reservoir, conduit, and contractile function of LA were evaluated by measuring LA volume (LAV) during different cardiac phases and all parameters were normalized to body surface area (BSA). Patients were divided into four groups (normal, impaired relaxation, pseudonormal, and restrictive LV diastolic filling) according to echocardiographic findings. The LA phasic volume and function in different stages of LV diastolic function was compared using one-way ANOVA analysis. The correlations between indexed volume of LA (LAVi) and diastolic function in different stages of LV were evaluated using Spearman correlation analysis. Results LA ejection fraction (LAEF), LA contraction, reservoir, and conduit function in patients in impaired relaxation group were not different from those in the normal group, but they were lower in patients in the pseudonormal and restrictive LV diastolic dysfunction groups (P < 0.05). For LA conduit function, there were no significant differences between the patients in the pseudonormal group and restrictive filling group (P = 0.195). There was a strong correlation between the indexed maximal left atrial volume (LAVmax, r = 0.85, P < 0.001), minimal left atrial volume (LAVmin, r = 0.91, P < 0.001), left atrial volume at the onset of P wave (LAVp, r = 0.84, P < 0.001), and different stages of LV diastolic function. The LAVi increased as the severity of LV diastolic dysfunction increased. Conclusions LA remodeling takes place in patients with LV diastolic dysfunction. At the same time, LA

  3. Conditional Reasoning in Context: A Dual-Source Model of Probabilistic Inference

    ERIC Educational Resources Information Center

    Klauer, Karl Christoph; Beller, Sieghard; Hutter, Mandy

    2010-01-01

    A dual-source model of probabilistic conditional inference is proposed. According to the model, inferences are based on 2 sources of evidence: logical form and prior knowledge. Logical form is a decontextualized source of evidence, whereas prior knowledge is activated by the contents of the conditional rule. In Experiments 1 to 3, manipulations of…

  4. Sources of Role Strain among Dual-Career Couples.

    ERIC Educational Resources Information Center

    Bird, Gloria W.; Ford, Rachel

    1985-01-01

    Examines the extent of role strain among husbands and wives in 69 dual-career couples. Results indicated that, for wives, number of children and importance of the parental role were significant predictors of role strain. For husbands, role strain was related to age of the youngest child and the extent to which child-care tasks were shared.…

  5. Simultaneous 1310/1550 dual-band swept laser source and fiber-based dual-band common-path swept source optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Mao, Youxin; Chang, Shoude; Murdock, Erroll; Flueraru, Costel

    2011-08-01

    A simultaneous two wavelength band swept laser source and a fiber-based dual-band common-path swept source optical coherence tomography is reported. Simultaneous 1310/1550 dual-wavelength tuning is performed by using two fiber-ring cavities with corresponding optical semiconductor amplifier as their gain mediums and two narrowband optical filters with a single dual-window polygonal scanner. Measured average output powers of 60 mW and 27 mW have been achieved for 1310 and 1550 nm bands, respectively, while the two wavelengths were swept simultaneously from 1227 nm to 1387 nm for 1310 nm band and from 1519 nm to 1581 nm for 1550 nm band at an A-scan rate of 65 kHz. A broadband 1310/1550 wavelength-division multiplexing is used for coupling two wavelengths into a common-path single-mode GRIN-lensed fiber probe to form a dual-band common-path swept-source optical coherence tomography. Simultaneous OCT imaging at 1310 and 1550 nm is achieved by using a depth ratio correction method. This technique allows potentially for in vivo endoscopic high-speed functional OCT imaging with high quality spectroscopic contrast with low computational costs. On the other hand, the common path configuration is able to reject common mode noise and potentially implement high stability quantitative phase measurements.

  6. DUAL HEATED ION SOURCE STRUCTURE HAVING ARC SHIFTING MEANS

    DOEpatents

    Lawrence, E.O.

    1959-04-14

    An ion source is presented for calutrons, particularly an electrode arrangement for the ion generator of a calutron ion source. The ion source arc chamber is heated and an exit opening with thermally conductive plates defines the margins of the opening. These plates are electrically insulated from the body of the ion source and are connected to a suitable source of voltage to serve as electrodes for shaping the ion beam egressing from the arc chamber.

  7. Source book for planning nuclear dual-purpose electric/distillation desalination plants

    SciTech Connect

    Reed, S.A.

    1981-02-01

    A source book on nuclear dual-purpose electric/distillation desalination plants was prepared to assist government and other planners in preparing broad evaluations of proposed applications of dual-purpose plants. The document is divided into five major sections. Section 1 presents general discussions relating to the benefits of dual-purpose plants, and spectrum for water-to-power ratios. Section 2 presents information on commercial nuclear plants manufactured by US manufacturers. Section 3 gives information on distillation desalting processes and equipment. Section 4 presents a discussion on feedwater pretreatment and scale control. Section 5 deals with methods for coupling the distillation and electrical generating plants to operate in the dual mode.

  8. Truncus arteriosus: Diagnosis with dual-source computed tomography angiography and low radiation dose

    PubMed Central

    Koplay, Mustafa; Cimen, Derya; Sivri, Mesut; Güvenc, Osman; Arslan, Derya; Nayman, Alaaddin; Oran, Bulent

    2014-01-01

    Truncus arteriosus is an uncommon congenital cardiac abnormality which is characterized by a single arterial trunk origin from the heart that supplies both the systemic, pulmonary and coronary circulation. We present a preterm newborn female patient with type 2 truncusarteriosus, left superior vena cava and aberrant subclavian artery diagnosed with low dose dual-source cardiac computed tomography (CT). We discuss that low dose dual-source cardiac CT has more advantages than other imaging methods and it is an important modality for assessment of patients with conotruncal anomalies such as truncusarteriosus. PMID:25431644

  9. Diffuse optical tomography using dual-interfering source

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Mu, Chenpeng; Intes, Xavier; Chance, Britton

    2002-04-01

    A frequency domain heterodyne system for recording the amplitude and phase of diffuse photon density wave (DPDW) is described here. We demonstrated experimentally the possibility of tomographic image reconstruction using a pair of out-of-phase sources. Both iterative method (SIRT) and subspace technique (SVD) have been used to address the inverse problem. The image quality with respect to the number of iterations and regularization numbers is discussed. Further investigations including the relationship between several parameters (such as modulation frequency, the source pair separation and the number of source and detectors) and the image quality are also discussed.

  10. Signal-to-noise analysis for detection sensitivity of small absorbing heterogeneity in turbid media with single-source and dual-interfering-source.

    PubMed

    Chen, Y; Mu, C; Intes, X; Chance, B

    2001-08-13

    Previous studies have suggested that the phased-array detection can achieve high sensitivity in detecting and localizing inhomogeneities embedded in turbid media by illuminating with dual interfering sources. In this paper, we analyze the sensitivity of single-source and dual-interfering-source (phased array) systems with signal-to-noise ratio criteria. Analytical solutions are presented to investigate the sensitivity of detection using different degrees of absorption perturbation by varying the size and contrast of the object under similar configurations for single- and dual-source systems. The results suggest that dual-source configuration can provide higher detection sensitivity. The relation between the amplitude and phase signals for both systems is also analyzed using a vector model. The results can be helpful for optimizing the experimental design by combining the advantages of both single- and dual-source systems in object detection and localization.

  11. Dual color x-rays from Thomson or Compton sources

    NASA Astrophysics Data System (ADS)

    Petrillo, V.; Bacci, A.; Curatolo, C.; Ferrario, M.; Maroli, C.; Rau, J. V.; Ronsivalle, C.; Serafini, L.; Vaccarezza, C.; Venturelli, M.

    2015-05-01

    We analyze the possibility of producing two color X or γ radiation by Thomson/Compton back-scattering between a high intensity laser pulse and a two-energy level electron beam, constituted by a couple of beamlets separated in time and/or energy obtained by a photoinjector with comb laser techniques and linac velocity bunching. The parameters of the Thomson source at SPARC_LAB have been simulated, proposing a set of values for a realistic experiments.

  12. Dual color x rays from Thomson or Compton sources

    NASA Astrophysics Data System (ADS)

    Petrillo, V.; Bacci, A.; Curatolo, C.; Ferrario, M.; Gatti, G.; Maroli, C.; Rau, J. V.; Ronsivalle, C.; Serafini, L.; Vaccarezza, C.; Venturelli, M.

    2014-02-01

    We analyze the possibility of producing two-color x or γ radiation by Thomson/Compton backscattering between a high intensity laser pulse and a two-energy level electron beam, constituted by a couple of beamlets separated in time and/or energy obtained by a photoinjector with comb laser techniques and linac velocity bunching. The parameters of the Thomson source at SPARC_LAB have been simulated, proposing a set of realistic experiments.

  13. Diagnostic Value of Dual-Source Computerized Tomography Combined with Perfusion Imaging for Peripheral Pulmonary Embolism

    PubMed Central

    Mao, Xijin; Wang, Shanshan; Jiang, Xingyue; Zhang, Lin; Xu, Wenjian

    2016-01-01

    Background Pulmonary embolism has become the third most common cardiovascular disease, which can seriously harm human health. Objectives To investigate the diagnostic value of dual-source computerized tomography (CT) and perfusion imaging for peripheral pulmonary embolism. Patients and Methods Thirty-two patients with suspected pulmonary embolism underwent dual-source CT exams. To compare the ability of pulmonary embolism detection software (PED) with CT pulmonary angiography (CTPA) in determining the presence, numbers, and locations of pulmonary emboli, the subsequent images were reviewed by two radiologists using both imaging modalities. Also, the diagnostic consistency between PED and CTPA images and dual-energy pulmonary perfusion imaging (DEPI) for segmental pulmonary embolism was compared. Results CTPA images revealed 50 (7.81%) segmental and 56 (4.38%) sub-segmental pulmonary embolisms, while the PED images showed 68 (10.63%) segmental and 94 (7.34%) sub-segmental pulmonary embolisms. Thus, the detection rate on PED images for peripheral pulmonary embolism was significantly higher than that of the CTPA images (P < 0.05). There was good consistency for diagnosing segmental pulmonary embolism between PED and CTPA and DEPI (kappa = 0.85). The sensitivity and specificity of DEPI images for the diagnosis of pulmonary embolism were 91.7% and 97.5%, respectively. Conclusion PED software of dual-source CT combined with perfusion imaging can significantly improve the detection rate of peripheral pulmonary embolism. PMID:27703656

  14. Optimization of energy level for coronary angiography with dual-energy and dual-source computed tomography.

    PubMed

    Okayama, Satoshi; Seno, Ayako; Soeda, Tsunenari; Takami, Yasuhiro; Kawakami, Rika; Somekawa, Satoshi; Ishigami, Ken-Ichi; Takeda, Yukiji; Kawata, Hiroyuki; Horii, Manabu; Uemura, Shiro; Saito, Yoshihiko

    2012-04-01

    Dual-energy computed tomography (DE-CT) uses polyenergetic X-rays at 100- and 140-kVp tube energy, and generates 120-kVp composite images that are referred to as polyenergetic images (PEIs). Moreover, DE-CT can produce monoenergetic images (MEIs) at any effective energy level. We evaluated whether the image quality of coronary angiography is improved by optimizing the energy levels of DE-CT. We retrospectively evaluated data sets obtained from 24 consecutive patients using cardiac DE-CT at 100- and 140-kVp tube energy with a dual-source scanner. Signal-to-noise ratios (SNRs) were evaluated in the left ascending coronary artery in PEIs, and in MEIs reconstructed at 40, 50, 60, 70, 80, 90, 100, 130, 160 and 190 keV. Energy levels of 100, 120 and 140 kVp generated the highest SNRs in PEIs from 10, 12 and 2 patients, respectively, at 60, 70 and 80 keV in MEIs from 2, 10 and 10 patients, respectively, and at 90 and 100 keV in those from one patient each. Optimization of the energy level for each patient increased the SNR by 16.6% in PEIs (P < 0.0001) and by 18.2% in MEIs (P < 0.05), compared with 120-kVp composite images. The image quality of coronary angiography using DE-CT can be improved by optimizing the energy level for individual patients.

  15. Bicomponent Fibrous Scaffolds Made through Dual-source Dual-power Electrospinning: Dual Delivery of rhBMP-2 and Ca-P Nanoparticles and Enhanced Biological Performances.

    PubMed

    Wang, Chong; Weijia Lu, William; Wang, Min

    2017-04-05

    Electrospun scaffolds incorporated with both calcium phosphates (Ca-P) and bone morphogenetic protein-2 (BMP-2) have been used for bone tissue regeneration. However, in most cases BMP-2 and Ca-P were simply mixed and loaded in a monolithic structure, risking low BMP-2 loading level, reduced BMP-2 biological activity, uncontrolled BMP-2 release and inhomogeneous Ca-P distribution. In this investigation, novel bicomponent scaffolds having evenly distributed rhBMP-2-containing fibers and Ca-P nanoparticle-containing fibers were made using an established dual-source dual-power electrospinning technique with the assistance of emulsion electrospinning and blend electrospinning. The release behaviour of rhBMP-2 and Ca(2+) ions could be separately tuned and the released rhBMP-2 retained a 68% level for biological activity. MC3T3-E1 cells showed high viability and normal morphology on scaffolds. Compared to monocomponent scaffolds, enhanced cell proliferation, alkaline phosphatase activity, cell mineralization and gene expression of osteogenic markers were achieved for bicomponent scaffolds due to the synergistic effect of rhBMP-2 and Ca-P nanoparticles. Bicomponent scaffolds with a double mass elicited further enhanced cell adhesion, spreading, proliferation and osteogenic differentiation. This article is protected by copyright. All rights reserved.

  16. A new coaxial high power microwave source based on dual beams

    SciTech Connect

    Li, Yangmei Zhang, Xiaoping; Qi, Zumin; Dang, Fangchao; Qian, Baoliang

    2014-05-15

    We present a new coaxial high power microwave source based on dual beams, which combines a relativistic backward wave oscillator (RBWO) (noted as the inner sub-source below) and a coaxial transit-time oscillator (TTO) (noted as the outer sub-source). The cathode consists of an inner and an outer annular cathode, which provides the inner and the outer annular electron beam for the sub-sources, respectively. Particle-in-cell (PIC) simulation results demonstrate that power conversion efficiencies of the two sub-sources with an identical frequency of 9.74 GHz are 29% and 25%, respectively. It is furthermore found that phase locking between the inner and the outer sub-sources can be realized, which suggests a feasibility to obtain a higher power output if the two microwave signals are coherently combined.

  17. A new coaxial high power microwave source based on dual beams

    NASA Astrophysics Data System (ADS)

    Li, Yangmei; Zhang, Xiaoping; Qi, Zumin; Dang, Fangchao; Qian, Baoliang

    2014-05-01

    We present a new coaxial high power microwave source based on dual beams, which combines a relativistic backward wave oscillator (RBWO) (noted as the inner sub-source below) and a coaxial transit-time oscillator (TTO) (noted as the outer sub-source). The cathode consists of an inner and an outer annular cathode, which provides the inner and the outer annular electron beam for the sub-sources, respectively. Particle-in-cell (PIC) simulation results demonstrate that power conversion efficiencies of the two sub-sources with an identical frequency of 9.74 GHz are 29% and 25%, respectively. It is furthermore found that phase locking between the inner and the outer sub-sources can be realized, which suggests a feasibility to obtain a higher power output if the two microwave signals are coherently combined.

  18. A High-Power Reflector Impulse Antenna with Dual-Tem Source

    NASA Astrophysics Data System (ADS)

    Guo, Chen; Zhang, An-Xue; Wu, Hui; Jiang, Yan-Sheng; Wang, Wen-Bing

    2008-09-01

    There are different demands on radiation efficiency and direction pattern according to various ultra-wideband (UWB) antennas and high power applications. To obtain more radiating gain on bore-sight of paraboloidal reflector and centralized radiating direction, a novel feeding structure called dual-TEM source has been designed and applied in half-paraboloidal reflector impulse radiating antenna (IRA) applications. Simulation results proved that this proposed half-paraboloidal reflector IRA with dual-TEM source provided greater radiation performance on bore-sight as a result of the synthesized power in the aperture space of paraboloid. Moreover, lots of simulation work and comparison have been done in different feeding models to summarize a relative optimal feeding structure.

  19. Dual-Source Multi-Energy CT with Triple or Quadruple X-ray Beams.

    PubMed

    Yu, Lifeng; Leng, Shuai; McCollough, Cynthia H

    2016-02-01

    Energy-resolved photon-counting CT (PCCT) is promising for material decomposition with multi-contrast agents. However, corrections for non-idealities of PCCT detectors are required, which are still active research areas. In addition, PCCT is associated with very high cost due to lack of mass production. In this work, we proposed an alternative approach to performing multi-energy CT, which was achieved by acquiring triple or quadruple x-ray beam measurements on a dual-source CT scanner. This strategy was based on a "Twin Beam" design on a single-source scanner for dual-energy CT. Examples of beam filters and spectra for triple and quadruple x-ray beam were provided. Computer simulation studies were performed to evaluate the accuracy of material decomposition for multi-contrast mixtures using a tri-beam configuration. The proposed strategy can be readily implemented on a dual-source scanner, which may allow material decomposition of multi-contrast agents to be performed on clinical CT scanners with energy-integrating detector.

  20. Dual-Source Multi-Energy CT with Triple or Quadruple X-ray Beams

    PubMed Central

    Yu, Lifeng; Leng, Shuai; McCollough, Cynthia H.

    2016-01-01

    Energy-resolved photon-counting CT (PCCT) is promising for material decomposition with multi-contrast agents. However, corrections for non-idealities of PCCT detectors are required, which are still active research areas. In addition, PCCT is associated with very high cost due to lack of mass production. In this work, we proposed an alternative approach to performing multi-energy CT, which was achieved by acquiring triple or quadruple x-ray beam measurements on a dual-source CT scanner. This strategy was based on a “Twin Beam” design on a single-source scanner for dual-energy CT. Examples of beam filters and spectra for triple and quadruple x-ray beam were provided. Computer simulation studies were performed to evaluate the accuracy of material decomposition for multi-contrast mixtures using a tri-beam configuration. The proposed strategy can be readily implemented on a dual-source scanner, which may allow material decomposition of multi-contrast agents to be performed on clinical CT scanners with energy-integrating detector. PMID:27330237

  1. Electrostatic energy harvesting device with dual resonant structure for wideband random vibration sources at low frequency.

    PubMed

    Zhang, Yulong; Wang, Tianyang; Zhang, Ai; Peng, Zhuoteng; Luo, Dan; Chen, Rui; Wang, Fei

    2016-12-01

    In this paper, we present design and test of a broadband electrostatic energy harvester with a dual resonant structure, which consists of two cantilever-mass subsystems each with a mass attached at the free edge of a cantilever. Comparing to traditional devices with single resonant frequency, the proposed device with dual resonant structure can resonate at two frequencies. Furthermore, when one of the cantilever-masses is oscillating at resonance, the vibration amplitude is large enough to make it collide with the other mass, which provides strong mechanical coupling between the two subsystems. Therefore, this device can harvest a decent power output from vibration sources at a broad frequency range. During the measurement, continuous power output up to 6.2-9.8 μW can be achieved under external vibration amplitude of 9.3 m/s(2) at a frequency range from 36.3 Hz to 48.3 Hz, which means the bandwidth of the device is about 30% of the central frequency. The broad bandwidth of the device provides a promising application for energy harvesting from the scenarios with random vibration sources. The experimental results indicate that with the dual resonant structure, the vibration-to-electricity energy conversion efficiency can be improved by 97% when an external random vibration with a low frequency filter is applied.

  2. Comparison between single- and dual-electrode ion source systems for low-energy ion transport

    SciTech Connect

    Vasquez, M. Jr.; Tokumura, S.; Kasuya, T.; Maeno, S.; Wada, M.

    2012-11-06

    Extraction of ions with energies below 100 eV has been demonstrated using a hot-cathode multi-cusp ion source equipped with extraction electrodes made of thin wires. Two electrode geometries, a single-electrode system, and a dual-electrode system were built and tested. The single-electrode configuration showed high ion beam current densities at shorter distances from the electrode but exhibited rapid attenuation as the distance from the electrode increased. Beam angular spread measurements showed similar beam divergence for both electrode configurations at low plasma densities. At high plasma densities and low extraction potentials, the single-electrode system showed the angular spread twice as large as that of the dual-electrode system. Energy distribution analyses showed a broader energy spread for ion beams extracted from a single-electrode set-up.

  3. A new compact self-coherent high power microwave source based on dual beams

    SciTech Connect

    Yan, Xiaolu Zhang, Xiaoping; Li, Yangmei; Qi, Zumin; Dang, Fangchao

    2015-05-15

    In this paper, a compact self-coherent high power microwave source based on dual beams is presented. It consists of a two-cavity triaxial klystron amplifier (TKA) (noted as the outer sub-source below) and a multiwave Cerenkov generators (noted as the inner sub-source) inserted in the TKA's inner conductor. These two sub-sources share a common cathode and the magnetic field. The injected signals to the outer sub-source are leakage microwaves from the inner sub-source through the anode-cathode gap (A-K gap). Particle-in-cell simulation shows that when the diode voltage is 687 kV and the axial magnetic field is 0.8 T, two microwaves with power of 1.02 GW and 2.65 GW and the same frequency of 9.72 GHz are generated in the inner and the outer sub-source, respectively; the corresponding power efficiencies are 24% and 31%. Two sub-sources reach the phase locking at 23 ns with a phase difference fluctuation within ±3°. The fast and stable phase locking in the voltage ranging from 665 kV to 709 kV further suggests that the proposed source is promising for coherent power combination and to export a higher power of combined microwaves.

  4. A new compact self-coherent high power microwave source based on dual beams

    NASA Astrophysics Data System (ADS)

    Yan, Xiaolu; Zhang, Xiaoping; Li, Yangmei; Qi, Zumin; Dang, Fangchao

    2015-05-01

    In this paper, a compact self-coherent high power microwave source based on dual beams is presented. It consists of a two-cavity triaxial klystron amplifier (TKA) (noted as the outer sub-source below) and a multiwave Cerenkov generators (noted as the inner sub-source) inserted in the TKA's inner conductor. These two sub-sources share a common cathode and the magnetic field. The injected signals to the outer sub-source are leakage microwaves from the inner sub-source through the anode-cathode gap (A-K gap). Particle-in-cell simulation shows that when the diode voltage is 687 kV and the axial magnetic field is 0.8 T, two microwaves with power of 1.02 GW and 2.65 GW and the same frequency of 9.72 GHz are generated in the inner and the outer sub-source, respectively; the corresponding power efficiencies are 24% and 31%. Two sub-sources reach the phase locking at 23 ns with a phase difference fluctuation within ±3°. The fast and stable phase locking in the voltage ranging from 665 kV to 709 kV further suggests that the proposed source is promising for coherent power combination and to export a higher power of combined microwaves.

  5. Quantitative assessment of scatter correction techniques incorporated in next generation dual-source computed tomography

    NASA Astrophysics Data System (ADS)

    Mobberley, Sean David

    Accurate, cross-scanner assessment of in-vivo air density used to quantitatively assess amount and distribution of emphysema in COPD subjects has remained elusive. Hounsfield units (HU) within tracheal air can be considerably more positive than -1000 HU. With the advent of new dual-source scanners which employ dedicated scatter correction techniques, it is of interest to evaluate how the quantitative measures of lung density compare between dual-source and single-source scan modes. This study has sought to characterize in-vivo and phantom-based air metrics using dual-energy computed tomography technology where the nature of the technology has required adjustments to scatter correction. Anesthetized ovine (N=6), swine (N=13: more human-like rib cage shape), lung phantom and a thoracic phantom were studied using a dual-source MDCT scanner (Siemens Definition Flash. Multiple dual-source dual-energy (DSDE) and single-source (SS) scans taken at different energy levels and scan settings were acquired for direct quantitative comparison. Density histograms were evaluated for the lung, tracheal, water and blood segments. Image data were obtained at 80, 100, 120, and 140 kVp in the SS mode (B35f kernel) and at 80, 100, 140, and 140-Sn (tin filtered) kVp in the DSDE mode (B35f and D30f kernels), in addition to variations in dose, rotation time, and pitch. To minimize the effect of cross-scatter, the phantom scans in the DSDE mode was obtained by reducing the tube current of one of the tubes to its minimum (near zero) value. When using image data obtained in the DSDE mode, the median HU values in the tracheal regions of all animals and the phantom were consistently closer to -1000 HU regardless of reconstruction kernel (chapters 3 and 4). Similarly, HU values of water and blood were consistently closer to their nominal values of 0 HU and 55 HU respectively. When using image data obtained in the SS mode the air CT numbers demonstrated a consistent positive shift of up to 35 HU

  6. Coronary fly-through or virtual angioscopy using dual-source MDCT data.

    PubMed

    van Ooijen, Peter M A; de Jonge, Gonda; Oudkerk, Matthijs

    2007-11-01

    Coronary fly-through or virtual angioscopy (VA) has been studied ever since its invention in 2000. However, application was limited because it requires an optimal computed tomography (CT) scan and time-consuming post-processing. Recent advances in post-processing software facilitate easy construction of VA, but until now image quality was insufficient in most patients. The introduction of dual-source multidetector CT (MDCT) could enable VA in all patients. Twenty patients were scanned using a dual-source MDCT (Definition, Siemens, Forchheim, Germany) using a standard coronary artery protocol. Post-processing was performed on an Aquarius Workstation (TeraRecon, San Mateo, Calif.). Length travelled per major branch was recorded in millimetres, together with the time required in minutes. VA could be performed in every patient for each of the major coronary arteries. The mean (range) length of the automated fly-through was 80 (32-107) mm for the left anterior descending (LAD), 75 (21-116) mm for the left circumflex artery (LCx), and 109 (21-190) mm for the right coronary artery (RCA). Calcifications and stenoses were visualised, as well as most side branches. The mean time required was 3 min for LAD, 2.5 min for LCx, and 2 min for the RCA. Dual-source MDCT allows for high quality visualisation of the coronary arteries in every patient because scanning with this machine is independent of the heart rate. This is clearly shown by the successful VA in all patients. Potential clinical value of VA should be determined in the near future.

  7. Supercontinuum optimization for dual-soliton based light sources using genetic algorithms in a grid platform.

    PubMed

    Arteaga-Sierra, F R; Milián, C; Torres-Gómez, I; Torres-Cisneros, M; Moltó, G; Ferrando, A

    2014-09-22

    We present a numerical strategy to design fiber based dual pulse light sources exhibiting two predefined spectral peaks in the anomalous group velocity dispersion regime. The frequency conversion is based on the soliton fission and soliton self-frequency shift occurring during supercontinuum generation. The optimization process is carried out by a genetic algorithm that provides the optimum input pulse parameters: wavelength, temporal width and peak power. This algorithm is implemented in a Grid platform in order to take advantage of distributed computing. These results are useful for optical coherence tomography applications where bell-shaped pulses located in the second near-infrared window are needed.

  8. Dual-etalon cavity ring-down frequency-comb spectroscopy with broad band light source

    DOEpatents

    Chandler, David W; Strecker, Kevin E

    2014-04-01

    In an embodiment, a dual-etalon cavity-ring-down frequency-comb spectrometer system is described. A broad band light source is split into two beams. One beam travels through a first etalon and a sample under test, while the other beam travels through a second etalon, and the two beams are recombined onto a single detector. If the free spectral ranges ("FSR") of the two etalons are not identical, the interference pattern at the detector will consist of a series of beat frequencies. By monitoring these beat frequencies, optical frequencies where light is absorbed may be determined.

  9. Preliminary experimental investigation of a complex dual-band high power microwave source

    SciTech Connect

    Zhang, Xiaoping Li, Yangmei; Li, Zhiqiang; Zhong, Huihuang; Qian, Baoliang

    2015-10-15

    In order to promote the power conversion efficiency of a magnetically insulated transmission line oscillator (MILO) and obtain microwaves in dual bands, an axially extracted C-band virtual cathode oscillator (VCO) with multiple resonant cavities is introduced to partially utilize the load current of an S-band MILO. The formed novel dual-band high power microwave source called MILO and VCO is investigated with simulation and experimentally. A dual-band radiation antenna is designed to effectively radiate microwaves generated by the MILO and the VCO, respectively, while avoiding them being influenced by the microwave reflection and diffraction. The preliminary experimental results measured by the dual-band diagnostic system show that both the MILO and the VCO operate normally under repeated shots. A microwave of 2.1 GHz, 1.70 GW is generated from the MILO and a 0.37 GW microwave at frequencies of 4.1 GHz and 3.8 GHz is generated from the VCO under the condition of about 440 kV and 35 kA. Compared with a single MILO (10.6%), a MILO and VCO achieves higher total power and efficiency (13.4%) in both S and C bands, indicating that the load current of the MILO partially couples into the beam-wave interaction in the VCO and then contributes to the output microwaves. However, more works are needed regarding the spectrum purification of the VCO and promotion of the output power of both the MILO and the VCO.

  10. Nonequilibrium atmospheric pressure plasma jet using a combination of 50 kHz/2 MHz dual-frequency power sources

    SciTech Connect

    Zhou, Yong-Jie; Yuan, Qiang-Hua; Li, Fei; Wang, Xiao-Min; Yin, Gui-Qin; Dong, Chen-Zhong

    2013-11-15

    An atmospheric pressure plasma jet is generated by dual sinusoidal wave (50 kHz and 2 MHz). The dual-frequency plasma jet exhibits the advantages of both low frequency and radio frequency plasmas, namely, the long plasma plume and the high electron density. The radio frequency ignition voltage can be reduced significantly by using dual-frequency excitation compared to the conventional radio frequency without the aid of the low frequency excitation source. A larger operating range of α mode discharge can be obtained using dual-frequency excitation which is important to obtain homogeneous and low-temperature plasma. A larger controllable range of the gas temperature of atmospheric pressure plasma could also be obtained using dual-frequency excitation.

  11. Frequency-domain endoscopic diffuse optical tomography reconstruction algorithm based on dual-modulation-frequency and dual-points source diffuse equation

    NASA Astrophysics Data System (ADS)

    Qin, Zhuanping; Hou, Qiang; Zhao, Huijuan; Yang, Yanshuang; Zhou, Xiaoqing; Gao, Feng

    2013-03-01

    In this paper, frequency-domain endoscopic diffuse optical tomography image reconstruction algorithm based on dual-modulation-frequency and dual-points source diffuse equation is investigated for the reconstruction of the optical parameters including the absorption and reducing scattering coefficients. The forward problem is solved by the finite element method based on the frequency domain diffuse equation (FD-DE) for dual-points source approximation and multi-modulation-frequency. In the image reconstruction, a multi-modulation-frequency Newton-Raphson algorithm is applied to obtain the solution. To further improve the image accuracy and quality, a method based on the region of interest (ROI) is applied on the above procedures. The simulation is performed in the tubular model to verify the validity of the algorithm. Results show that the FD-DE with dual-points source approximate is more accuracy at shorter source-detector separation. The reconstruction with dual-modulation-frequency improves the image accuracy and quality compared to the results with single-modulation-frequency and triple-modulation-frequency method. The peak optical coefficients in ROI (ROI_max) are almost equivalent to the true optical coefficients with the relative error less than 6.67%. The full width at half maximum (FWHM) achieves 82% of the true radius. The contrast-to-noise ratio (CNR) and image coefficient(IC) is 5.678 and 26.962, respectively. Additionally, the results with the method based on ROI show that the ROI_max is equivalent to the true value. The FWHM can improve by 88% of the true radius. The CNR and IC is improved over 7.782 and 45.335, respectively.

  12. Probabilistic conditional reasoning: Disentangling form and content with the dual-source model.

    PubMed

    Singmann, Henrik; Klauer, Karl Christoph; Beller, Sieghard

    2016-08-01

    The present research examines descriptive models of probabilistic conditional reasoning, that is of reasoning from uncertain conditionals with contents about which reasoners have rich background knowledge. According to our dual-source model, two types of information shape such reasoning: knowledge-based information elicited by the contents of the material and content-independent information derived from the form of inferences. Two experiments implemented manipulations that selectively influenced the model parameters for the knowledge-based information, the relative weight given to form-based versus knowledge-based information, and the parameters for the form-based information, validating the psychological interpretation of these parameters. We apply the model to classical suppression effects dissecting them into effects on background knowledge and effects on form-based processes (Exp. 3) and we use it to reanalyse previous studies manipulating reasoning instructions. In a model-comparison exercise, based on data of seven studies, the dual-source model outperformed three Bayesian competitor models. Overall, our results support the view that people make use of background knowledge in line with current Bayesian models, but they also suggest that the form of the conditional argument, irrespective of its content, plays a substantive, yet smaller, role.

  13. A stochastic inventory management model for a dual sourcing supply chain with disruptions

    NASA Astrophysics Data System (ADS)

    Iakovou, Eleftherios; Vlachos, Dimitrios; Xanthopoulos, Anastasios

    2010-03-01

    As companies continue to globalise their operations and outsource significant portion of their value chain activities, they often end up relying heavily on order replenishments from distant suppliers. The explosion in long-distance sourcing is exposing supply chains and shareholder value at ever increasing operational and disruption risks. It is well established, both in academia and in real-world business environments, that resource flexibility is an effective method for hedging against supply chain disruption risks. In this contextual framework, we propose a single period stochastic inventory decision-making model that could be employed for capturing the trade-off between inventory policies and disruption risks for an unreliable dual sourcing supply network for both the capacitated and uncapacitated cases. Through the developed model, we obtain some important managerial insights and evaluate the merit of contingency strategies in managing uncertain supply chains.

  14. Correction of cross-scatter in next generation dual source CT (DSCT) scanners

    NASA Astrophysics Data System (ADS)

    Bruder, H.; Stierstorfer, K.; Petersilka, M.; Wiegand, C.; Suess, C.; Flohr, T.

    2008-03-01

    In dual source CT (DSCT) with two X-ray sources and two data measurement systems mounted on a CT gantry with a mechanical offset of 90 deg, cross scatter radiation, (essentially 90 deg Compton scatter) is added to the detector signals. In current DSCT scanners the cross scatter correction is model based: the idea is to describe the scattering surface in terms of its tangents. The positions of these tangent lines are used to characterize the shape of the scattering object. For future DSCT scanners with larger axial X-ray beams, the model based correction will not perfectly remove the scatter signal in certain clinical situations: for obese patients scatter artifacts in cardiac dual source scan modes might occur. These shortcomings can be circumvented by utilizing the non-diagnostic time windows in cardiac scan modes to detect cross scatter online. The X-ray generators of both systems have to be switched on and off alternating. If one X-ray source is switched off, cross scatter deposited in the respective other detector can be recorded and processed, to be used for efficient cross scatter correction. The procedure will be demonstrated for cardiac step&shoot as well as for spiral acquisitions. Full rotation reconstructions are less sensitive to cross scatter radiation; hence in non-cardiac case the model-based approach is sufficient. Based on measurements of physical and anthropomorphic phantoms we present image data for DSCT systems with various collimator openings demonstrating the efficacy of the proposed method. In addition, a thorough analysis of contrast-to-noise ratio (CNR) shows, that even for a X-ray beam corresponding to a 64x0.6 mm collimation, the maximum loss of CNR due to cross scatter is only about 7% in case of obese patients.

  15. Nitrogen sources and cycling in the San Francisco Bay estuary: A nitrate dual isotopic composition approach

    USGS Publications Warehouse

    Wankel, Scott D.; Kendall, C.; Francis, C.A.; Paytan, A.

    2006-01-01

    We used the dual isotopic composition of nitrate (??15N and ??18O) within the estuarine system of San Francisco (SF) Bay, California, to explore the utility of this approach for tracing sources and cycling of nitrate (NO3-). Surface water samples from 49 sites within the estuary were sampled during July-August 2004. Spatial variability in the isotopic composition suggests that there are multiple sources of nitrate to the bay ecosystem including seawater, several rivers and creeks, and sewage effluent. The spatial distribution of nitrate from these sources is heavily modulated by the hydrodynamics of the estuary. Mixing along the estuarine salinity gradient is the main control on the spatial variations in isotopic composition of nitrate within the northern arm of SF Bay. However, the nitrate isotopic composition in the southern arm of SF Bay exhibited a combination of source mixing and phytoplankton drawdown due mostly to the long residence time during the summer study period. Very low ?? 18ONO3 values (as low as -5.0???) at the Sacramento-San Joaquin River delta region give rise to a wide range of ??18ONO3 values in the SF Bay system. The range in ??18ONO3 values is more than twice that of (??15NNO3, suggesting that ??18O NO3 is an even more sensitive tool for tracing nitrate sources and cycling than ??15NNO3. ?? 2006, by the American Society of Limnology and Oceanography, Inc.

  16. Radiant, virtual, and dual sources of optical fields in any state of spatial coherence.

    PubMed

    Castañeda, Román; Cañas-Cardona, Gustavo; Garcia-Sucerquia, Jorge

    2010-06-01

    A novel description of interference and diffraction with fields in arbitrary states of spatial coherence is introduced in the framework of the phase-space representation. The field is modeled as produced by radiant and virtual point sources. The first ones emit the radiant power of the field, independently of its spatial coherence state, and the second ones emit the modulating energy in strong dependence on such state. This energy can take on positive and negative values that produce the interference and diffraction patterns after adding them to the radiant energy. Radiant and virtual point sources at a given plane can be arranged over two distinct layers, which can be brought together to provide a unified structure of point sources for the field at such plane. So, the coincidence of specific radiant and virtual sources at the same point induces a further type: the dual point source. Descriptions of diffraction arrangements, Young's experiment with diffraction effects, and some implications of this model are discussed.

  17. Miniaturized silicon photonic integrated swept source OCT receiver with dual polarization, dual balanced, in-phase and quadrature detection (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wang, Zhao; Lee, Hsiang-Chieh; Chen, Long; Vermeulen, Diedrik; Nielsen, Torben; Park, Seo Yeon; Ghaemi, Allan; Swanson, Eric; Doerr, Chris; Fujimoto, James

    2016-03-01

    Miniaturization and cost reduction of OCT systems are important for enabling many new clinical applications as well as accelerating the development of existing applications. Silicon photonics is an important low-cost, high-volume, multi-functional platform for integrated optics because it can benefit from existing semiconductor fabrication techniques to integrate many advanced optical functions onto a single microchip. We present a miniaturized silicon photonic integrated swept source OCT receiver, measuring 3×4mm2, with advanced functionalities including dual polarization, dual balanced, in-phase and quadrature detection, essentially enabling the detection of the full vector field (amplitude, phase, and polarization) of the optical signal. With this integrated receiver, we demonstrate full-range OCT for complex conjugate artifact suppression, polarization diversity detection for removing polarization fading artifact, and polarization sensitive OCT for tissue birefringence imaging. The silicon photonic integrated receiver is a key advance towards developing a miniaturized, multi-functional swept source OCT system.

  18. A dual-isotope approach to allow conclusive partitioning between three sources

    PubMed Central

    Whitman, Thea; Lehmann, Johannes

    2015-01-01

    Stable isotopes have proved to be a transformative tool; their application to distinguish between two sources in a mixture has been a cornerstone of biogeochemical research. However, quantitatively partitioning systems using two stable isotopes (for example, 13C and 12C) has been largely limited to only two sources, and systems of interest often have more than two components, with interactive effects. Here we introduce a dual-isotope approach to allow conclusive partitioning between three sources, using only two stable isotopes. We demonstrate this approach by partitioning soil CO2 emissions derived from microbial mineralization of soil organic carbon (SOC), added pyrogenic organic matter (PyOM) and root respiration. We find that SOC mineralization in the presence of roots is 23% higher (P<0.05) when PyOM is also present. Being able to discern three sources with two isotopes will be of great value not only in biogeochemical research, but may also expand hitherto untapped methodologies in diverse fields. PMID:26530521

  19. Broadly tunable femtosecond mid-infrared source based on dual photonic crystal fibers.

    PubMed

    Yao, Yuhong; Knox, Wayne H

    2013-11-04

    We report a novel scheme of generating broadly tunable femtosecond mid-IR pulses based on difference frequency mixing the outputs from dual photonic crystal fibers (PCF). With a 1.3 W, 1035 nm, 300 fs and 40 MHz Yb fiber chirped pulse amplifier as the laser source, a PCF with single zero dispersion wavelength (ZDW) at the laser wavelength is employed to spectrally broaden a portion of the laser pulses. Facilitated by self-phase modulation, its output spectrum possesses two dominant outermost peaks that can be extended to 970 nm and 1092 nm. A different PCF with two closely spaced ZDWs around the laser wavelength is used to generate the intense Stokes pulses between 1240 - 1260 nm. Frequency mixing the dual PCFs outputs in an AgGaS(2) crystal results in mid-IR pulses broadly tunable from 4.2 μm to 9 μm with a maximum average power of 640 µW at 4.5 μm, corresponding to 16 pJ of pulse energy.

  20. Wet-chemical synthesis of different bismuth telluride nanoparticles using metal organic precursors - single source vs. dual source approach.

    PubMed

    Bendt, Georg; Weber, Anna; Heimann, Stefan; Assenmacher, Wilfried; Prymak, Oleg; Schulz, Stephan

    2015-08-28

    Thermolysis of the single source precursor (Et2Bi)2Te in DIPB at 80 °C yielded phase-pure Bi4Te3 nanoparticles, while mixtures of Bi4Te3 and elemental Bi were formed at higher temperatures. In contrast, cubic Bi2Te particles were obtained by thermal decomposition of Et2BiTeEt in DIPB. Moreover, a dual source approach (hot injection method) using the reaction of Te(SiEt3)2 and Bi(NMe2)3 was applied for the synthesis of different pure Bi-Te phases including Bi2Te, Bi4Te3 and Bi2Te3, which were characterized by PXRD, REM, TEM and EDX. The influence of reaction temperature, precursor molar ratio and thermolysis conditions on the resulting material phase was verified. Moreover, reactions of alternate bismuth precursors such as Bi(NEt2)3, Bi(NMeEt)3 and BiCl3 with Te(SiEt3)2 were investigated.

  1. Financial Impact of Dual Vendor, Matrix Pricing, and Sole-Source Contracting on Implant Costs.

    PubMed

    Althausen, Peter L; Lapham, Joan; Mead, Lisa

    2016-12-01

    Implant costs comprise the largest proportion of operating room supply costs for orthopedic trauma care. Over the years, hospitals have devised several methods of controlling these costs with the help of physicians. With increasing economic pressure, these negotiations have a tremendous ability to decrease the cost of trauma care. In the past, physicians have taken no responsibility for implant pricing which has made cost control difficult. The reasons have been multifactorial. However, industry surgeon consulting fees, research support, and surgeon comfort with certain implant systems have played a large role in slowing adoption of cost-control measures. With the advent of physician gainsharing and comanagement agreements, physicians now have impetus to change. At our facility, we have used 3 methods for cost containment since 2009: dual vendor, matrix pricing, and sole-source contracting. Each has been increasingly successful, resulting in massive savings for the institution. This article describes the process and benefits of each model.

  2. Spatiotemporal optical similaritons in dual-core waveguide with an external source

    NASA Astrophysics Data System (ADS)

    Soloman Raju, Thokala

    2017-04-01

    We explore analytically and numerically the existence of exact asymptotic spatiotemporal optical self-similar light bullets to the nonlinear Schrödinger equation with gain in the presence of an external source in (3+1)-dimensions. This model appertains to the description of self-similar wave propagation through asymmetric planar dual-core waveguide (DWG) amplifiers. The asymmetric DWG is composed of two adjoining, closely spaced, upper and lower waveguides, in which the lower one acts as a passive waveguide while the upper waveguide is an active one. Due to the linear coupling between them, we can control the dynamical behaviors of the wave propagating through the passive waveguide by controlling the wave in active waveguide. We explicate the mechanism to control the dynamical behaviors of these self-similar waves for two specific cases: (i) when the gain and width are hyperbolic functions and (ii) when the gain and width are periodic functions.

  3. New normative standards of conditional reasoning and the dual-source model.

    PubMed

    Singmann, Henrik; Klauer, Karl Christoph; Over, David

    2014-01-01

    There has been a major shift in research on human reasoning toward Bayesian and probabilistic approaches, which has been called a new paradigm. The new paradigm sees most everyday and scientific reasoning as taking place in a context of uncertainty, and inference is from uncertain beliefs and not from arbitrary assumptions. In this manuscript we present an empirical test of normative standards in the new paradigm using a novel probabilized conditional reasoning task. Our results indicated that for everyday conditional with at least a weak causal connection between antecedent and consequent only the conditional probability of the consequent given antecedent contributes unique variance to predicting the probability of conditional, but not the probability of the conjunction, nor the probability of the material conditional. Regarding normative accounts of reasoning, we found significant evidence that participants' responses were confidence preserving (i.e., p-valid in the sense of Adams, 1998) for MP inferences, but not for MT inferences. Additionally, only for MP inferences and to a lesser degree for DA inferences did the rate of responses inside the coherence intervals defined by mental probability logic (Pfeifer and Kleiter, 2005, 2010) exceed chance levels. In contrast to the normative accounts, the dual-source model (Klauer et al., 2010) is a descriptive model. It posits that participants integrate their background knowledge (i.e., the type of information primary to the normative approaches) and their subjective probability that a conclusion is seen as warranted based on its logical form. Model fits showed that the dual-source model, which employed participants' responses to a deductive task with abstract contents to estimate the form-based component, provided as good an account of the data as a model that solely used data from the probabilized conditional reasoning task.

  4. Source apportionment of carbonaceous aerosols over South and East Asia using dual carbon isotopes

    NASA Astrophysics Data System (ADS)

    Gustafsson, O.; Kirillova, E. N.; Andersson, A.-; Kruså, M.; Sheesley, R. J.; Tiwari, S.-; Lee, M.; Chen, B.; Du, K.

    2012-12-01

    contrary to the isotopic gradient expected for secondary organic aerosol (SOA) formation and instead suggests that WSOC in the South Asian regional receptor atmosphere stems largely from chemically-aged POA. The year-round dual-isotope data suggests that a key contribution to S Asian WSOC may be ageing of POA from incomplete biomass combustion. These top-down isotope-based observational constraints is favorably combined with bottom-up emission inventories to iteratively produce an improved understanding of both anthropogenic sources and atmospheric behavior of climate- and health-afflicting carbonaceous aerosols in the air of South and East Asia.

  5. Investigation of a dual-isotope approach to trace nitrate sources in groundwater systems

    NASA Astrophysics Data System (ADS)

    Fukada, T.; Hiscock, K. M.; Dennis, P. F.

    2002-12-01

    Nitrate contamination in groundwater has long been an issue in Europe, with reported high nitrate concentrations in drinking water of greater than 10 mg/L NO3-N, as defined by the World Health Organisation, posing various health risks. Identifying the sources and fate of nitrate in groundwater is part of the solution to nitrate contamination. Several methods have been reported for identifying nitrogen sources, such as the single isotope method using the nitrogen isotopes of nitrate, but the methods present difficulties, such as ambiguity of interpretation. In this study, and by adopting a dual-isotope approach, with measurements of oxygen as well as nitrogen isotopes of nitrate, we have been able to identify the sources and fate of nitrate in groundwater with greater confidence. To investigate the approach, we collected groundwater samples from a Pleistocene alluvial aquifer at a bank filtration site in Germany, the Cretaceous Chalk aquifer in rural eastern England, the Triassic sandstone aquifer in the urban English Midlands and also from controlled laboratory columns treated with pig manure. The values of nitrogen isotopes in groundwater nitrate sources were in the range of -0.13 to +5.64 % for inorganic fertiliser, +9.26 to +11.44 % for urban sewerage and +8.99 to +13.61 % for pig manure. Values of the oxygen isotopes in groundwater nitrate sources were in the range of +3.46 to +16.00 % for inorganic fertiliser, +8.21to +10.77 % for sewerage and +10.73 to +12.07 % for pig manure. We also observed that those sites experiencing denitrification produced a linear relationship indicating an enrichment of the heavier nitrogen isotope relative to the heavier oxygen isotope by a factor of 1.3 and 1.9.

  6. An insight into the western Pacific wintertime moisture sources using dual water vapor isotopes

    NASA Astrophysics Data System (ADS)

    Rangarajan, Ravi; Laskar, Amzad H.; Bhattacharya, Sourendra K.; Shen, Chuan-Chou; Liang, Mao-Chang

    2017-04-01

    Continuous measurements of isotopic ratios in atmospheric water vapor in a western Pacific region (Taipei, Taiwan) in two winters (2011 and 2012) were made and analyzed to understand the moisture source characteristics. In wintertime, the so-called East Asian Monsoon dominates, largely affecting the climate and meteorology of this region. Being located in the subtropical region, Taipei provides an ideal opportunity for studying interactions between high latitude cold and dry continental air masses and low to mid-latitude warm and wet oceanic air. Indeed, the dual isotope function, d-excess shows the presence of two distinct moisture sources, contributing to the winter vapor isotope variability. Undoubtedly, the dominant moisture source is the high latitude continental cold air masses reaching Taipei with d-excess values of >20‰. Alongside, wet and warm air masses characterized by strong air-sea interaction from the surrounding oceans, possessing d-excess value of ∼10‰ also play a role. The interactions of these two distinct air masses cause the d-excess values to change by as much as ∼20‰ in a few days. Multiple regression analysis shows that source moisture composition and water vapor mixing ratio combined control over 60% of the observed variability. We developed a box model to show that both high and low d-excess events in the winter are primarily controlled by the humidity deficit over the ocean. The information obtained in this study could be used in interpreting the paleoclimate proxies within the East Asian region.

  7. Material differentiation in forensic radiology with single-source dual-energy computed tomography.

    PubMed

    Ruder, Thomas D; Thali, Yannick; Bolliger, Stephan A; Somaini-Mathier, Sandra; Thali, Michael J; Hatch, Gary M; Schindera, Sebastian T

    2013-06-01

    The goal of this study was to investigate the use of dual-energy computed tomography (CT) in differentiating frequently encountered foreign material on CT images using a standard single-source CT scanner. We scanned 20 different, forensically relevant materials at two X-Ray energy levels (80 and 130 kVp) on CT. CT values were measured in each object at both energy levels. Intraclass correlation coefficient (ICC) was used to determine intra-reader reliability. Analysis of variance (ANOVA) was performed to assess significance levels between X-Ray attenuation at 80 and 130 kVp. T test was used to investigate significance levels between mean HU values of individual object pairings at single energy levels of 80 and 130 kVp, respectively. ANOVA revealed that the difference in attenuation between beam energies of 80 kVp compared to 130 kVp was statistically significant (p < 0.005) for all materials except brass and lead. ICC was excellent at 80 kVp (0.999, p < 0.001) and at 130 kVp (0.998, p < 0.001). T test showed that using single energy levels of 80 and 130 kVp respectively 181/190 objects pairs could be differentiated from one another based on HU measurements. Using the combined information from both energy levels, 189/190 object pairs could be differentiated. Scanning with different energy levels is a simple way to apply dual-energy technique on a regular single-energy CT and improves the ability to differentiate foreign bodies with CT, based on their attenuation values.

  8. Electrocortical Sources Related to Whole-Body Surface Translations during a Single- and Dual-Task Paradigm

    PubMed Central

    Bogost, Mark D.; Burgos, Pablo I.; Little, C. Elaine; Woollacott, Marjorie H.; Dalton, Brian H.

    2016-01-01

    Appropriate reactive motor responses are essential in maintaining upright balance. However, little is known regarding the potential location of cortical sources that are related to the onset of a perturbation during single- and dual-task paradigms. The purpose of this study was to estimate the location of cortical sources in response to a whole-body surface translation and whether diverted attention decreases the N1 event-related potential (ERP) amplitude related to a postural perturbation. This study utilized high-resolution electroencephalography in conjunction with measure projection analysis from ERPs time-locked to backwards surface translation onsets to determine which cortical sources were related to whole-body postural perturbations. Subjects (n = 15) either reacted to whole-body surface translations with (dual task) or without (single task) performing a visual working memory task. For the single task, four domains were identified that were mainly localized within the frontal and parietal lobes and included sources from the prefrontal, premotor, primary and supplementary motor, somatosensory and anterior cingulate cortex. Five domains were estimated for the dual task and also included sources within the frontal and parietal lobes, but the sources also shifted to other locations that included areas within the temporal and occipital lobes. Additionally, mean absolute N1 ERP amplitudes representing the activity from similar locations in both tasks were greater for the single than dual task. The present localization results highlight the importance of frontal, parietal and anterior cingulate cortical areas in reactive postural control and suggest a re-allocation or shift of cortical sources related to reactive balance control in the presence of a secondary task. Thus, this study provides novel insight into the underlying neurophysiology and contribution of cortical sources in relation to the neural control of reactive balance. PMID:27803658

  9. Dual diagnosis, as described by those who experience the disorder: using the Internet as a source of data.

    PubMed

    Edward, Karen-Leigh; Robins, Alan

    2012-12-01

    The complexity of providing treatment for people with dual diagnosis is well recognized. For the purpose of this paper, the World Health Organization definition of dual diagnosis was used; that is, a person diagnosed with an alcohol or drug use problem in addition to mental illness. This research explored the personal narratives of those who experience dual diagnosis using the Internet as a data source. An important consideration in using the Internet as a data source was that Web forums can offer a sense of anonymity, allowing people to share very detailed and personal information, and providing a rich source of qualitative data. The results produced five emergent themes: spiralling out of control - again!, getting help and giving support, treating both the addiction and mental illness, having meaning and being active, and being honest with self and others. The results indicate that individuals who experience dual diagnosis are often left to navigate their personal treatment requirements across two diverse systems, and were generally not satisfied with the conflictual advice received across these two systems (i.e. alcohol and other drug and mental health services). This study has produced valuable insights related to consumer-perceived service barriers and enablers.

  10. Dual-core ytterbium fiber amplifier for high-power 1060 nm swept source multichannel optical coherence tomography imaging.

    PubMed

    Harduar, Mark K; Mariampillai, Adrian; Vuong, Barry; Gu, Xijia; Standish, Beau A; Yang, Victor X D

    2011-08-01

    A novel (to our knowledge) dual-core ytterbium (Yb(3+)) doped fiber, as an optically pumped amplifier, boosts the output power from a 1060 nm swept source laser beyond 250 mW, while providing a wavelength tuning range of 93 nm, for optical coherence tomography (OCT) imaging. The design of the dual-core Yb-doped fiber amplifier and its multiple wavelength optical pumping scheme to optimize output bandwidth are discussed. Use of the dual-core fiber amplifier showed no appreciable degradation to the coherence length of the seed laser. The signal intensity improvement of this amplifier is demonstrated on a multichannel in vivo OCT imaging system at 1060 nm.

  11. Desired lifetime and end-of-life desires across adulthood from 20 to 90: a dual-source information model.

    PubMed

    Lang, Frieder R; Baltes, Paul B; Wagner, Gert G

    2007-09-01

    How long do people want to live, and how does scientific research on aging affect such desires? A dual-source information model proposes that aging expectations and desires are informed differently by two sources: personal experiences on the one hand, and scientific and societal influences on the other. Two studies with independent German national samples explored desires regarding length of life and end of life among adults between the ages of 20 and 90. FINDINGS ARE: First, desired lifetime is consistent at around 85 years with few age differences. Second, experimental induction of good or bad news from research on aging has little effect in Study 1. Third, interest in science has moderating effects on desired lifetime in Study 2. Fourth, there is a high prevalence of a strong desire to control the "when and how" of one's death, although only 11% of the individuals completed a living will. Findings are consistent with the dual-source information model.

  12. Dual electrospray ion source for electron-transfer dissociation on a hybrid linear ion trap-orbitrap mass spectrometer.

    PubMed

    Williams, D Keith; McAlister, Graeme C; Good, David M; Coon, Joshua J; Muddiman, David C

    2007-10-15

    A dual electrospray ionization source (ESI) has been modified to simultaneously produce cations and anions, one from each emitter, for performing rapid electron-transfer dissociation (ETD) ion/ion reactions on a hybrid linear ion trap-orbitrap mass spectrometer. Unlike the pulsed dual ESI sources that were used to generate ETD reagent ions, this source separates the emitters in space, rather than time, by physically switching which one is in front of the atmospheric inlet. The new arrangement allows for substantially enhanced spray stability and decreased switching times (

  13. Sources and transformations of nitrate from streams draining varying land uses: Evidence from dual isotope analysis

    USGS Publications Warehouse

    Burns, Douglas A.; Boyer, E.W.; Elliott, E.M.; Kendall, C.

    2009-01-01

    Knowledge of key sources and biogeochemical processes that affect the transport of nitrate (NO3-) in streams can inform watershed management strategies for controlling downstream eutrophication. We applied dual isotope analysis of NO3- to determine the dominant sources and processes that affect NO3- concentrations in six stream/river watersheds of different land uses. Samples were collected monthly at a range of flow conditions for 15 mo during 2004-05 and analyzed for NO3- concentrations, ?? 15NNO3, and ??18ONO3. Samples from two forested watersheds indicated that NO3- derived from nitrification was dominant at baseflow. A watershed dominated by suburban land use had three ??18ONO3 values greater than +25???, indicating a large direct contribution of atmospheric NO 3- transported to the stream during some high flows. Two watersheds with large proportions of agricultural land use had many ??15NNO3 values greater than +9???, suggesting an animal waste source consistent with regional dairy farming practices. These data showed a linear seasonal pattern with a ??18O NO3:??15NNO3 of 1:2, consistent with seasonally varying denitrification that peaked in late summer to early fall with the warmest temperatures and lowest annual streamflow. The large range of ?? 15NNO3 values (10???) indicates that NO 3- supply was likely not limiting the rate of denitrification, consistent with ground water and/or in-stream denitrification. Mixing of two or more distinct sources may have affected the seasonal isotope patterns observed in these two agricultural streams. In a mixed land use watershed of large drainage area, none of the source and process patterns observed in the small streams were evident. These results emphasize that observations at watersheds of a few to a few hundred km2 may be necessary to adequately quantify the relative roles of various NO 3- transport and process patterns that contribute to streamflow in large basins. Copyright ?? 2009 by the American Society of

  14. Identifying diffused nitrate sources in a stream in an agricultural field using a dual isotopic approach.

    PubMed

    Ding, Jingtao; Xi, Beidou; Gao, Rutai; He, Liansheng; Liu, Hongliang; Dai, Xuanli; Yu, Yijun

    2014-06-15

    Nitrate (NO3(-)) pollution is a severe problem in aquatic systems in Taihu Lake Basin in China. A dual isotope approach (δ(15)NNO3(-) and δ(18)ONO3(-)) was applied to identify diffused NO3(-) inputs in a stream in an agricultural field at the basin in 2013. The site-specific isotopic characteristics of five NO3(-) sources (atmospheric deposition, AD; NO3(-) derived from soil organic matter nitrification, NS; NO3(-) derived from chemical fertilizer nitrification, NF; groundwater, GW; and manure and sewage, M&S) were identified. NO3(-) concentrations in the stream during the rainy season [mean±standard deviation (SD)=2.5±0.4mg/L] were lower than those during the dry season (mean±SD=4.0±0.5mg/L), whereas the δ(18)ONO3(-) values during the rainy season (mean±SD=+12.3±3.6‰) were higher than those during the dry season (mean±SD=+0.9±1.9‰). Both chemical and isotopic characteristics indicated that mixing with atmospheric NO3(-) resulted in the high δ(18)O values during the rainy season, whereas NS and M&S were the dominant NO3(-) sources during the dry season. A Bayesian model was used to determine the contribution of each NO3(-) source to total stream NO3(-). Results showed that reduced N nitrification in soil zones (including soil organic matter and fertilizer) was the main NO3(-) source throughout the year. M&S contributed more NO3(-) during the dry season (22.4%) than during the rainy season (17.8%). AD generated substantial amounts of NO3(-) in May (18.4%), June (29.8%), and July (24.5%). With the assessment of temporal variation of diffused NO3(-) sources in agricultural field, improved agricultural management practices can be implemented to protect the water resource and avoid further water quality deterioration in Taihu Lake Basin.

  15. Adaptive optics OCT using 1060nm swept source and dual deformable lenses for human retinal imaging

    NASA Astrophysics Data System (ADS)

    Jian, Yifan; Lee, Sujin; Cua, Michelle; Miao, Dongkai; Bonora, Stefano; Zawadzki, Robert J.; Sarunic, Marinko V.

    2016-03-01

    Adaptive optics concepts have been applied to the advancement of biological imaging and microscopy. In particular, AO has also been very successfully applied to cellular resolution imaging of the retina, enabling visualization of the characteristic mosaic patterns of the outer retinal layers using flood illumination fundus photography, Scanning Laser Ophthalmoscopy (SLO), and Optical Coherence Tomography (OCT). Despite the high quality of the in vivo images, there has been a limited uptake of AO imaging into the clinical environment. The high resolution afforded by AO comes at the price of limited field of view and specialized equipment. The implementation of a typical adaptive optics imaging system results in a relatively large and complex optical setup. The wavefront measurement is commonly performed using a Hartmann-Shack Wavefront Sensor (HS-WFS) placed at an image plane that is optically conjugated to the eye's pupil. The deformable mirror is also placed at a conjugate plane, relaying the wavefront corrections to the pupil. Due to the sensitivity of the HS-WFS to back-reflections, the imaging system is commonly constructed from spherical mirrors. In this project, we present a novel adaptive optics OCT retinal imaging system with significant potential to overcome many of the barriers to integration with a clinical environment. We describe in detail the implementation of a compact lens based wavefront sensorless adaptive optics (WSAO) 1060nm swept source OCT human retinal imaging system with dual deformable lenses, and present retinal images acquired in vivo from research volunteers.

  16. Dual-Source Precursor Approach for Highly Efficient Inverted Planar Heterojunction Perovskite Solar Cells.

    PubMed

    Luo, Deying; Zhao, Lichen; Wu, Jiang; Hu, Qin; Zhang, Yifei; Xu, Zhaojian; Liu, Yi; Liu, Tanghao; Chen, Ke; Yang, Wenqiang; Zhang, Wei; Zhu, Rui; Gong, Qihuang

    2017-03-15

    The highest efficiencies reported for perovskite solar cells so far have been obtained mainly with methylammonium and formamidinium mixed cations. Currently, high-quality mixed-cation perovskite thin films are normally made by use of antisolvent protocols. However, the widely used "antisolvent"-assisted fabrication route suffers from challenges such as poor device reproducibility, toxic and hazardous organic solvent, and incompatibility with scalable fabrication process. Here, a simple dual-source precursor approach is developed to fabricate high-quality and mirror-like mixed-cation perovskite thin films without involving additional antisolvent process. By integrating the perovskite films into the planar heterojunction solar cells, a power conversion efficiency of 20.15% is achieved with negligible current density-voltage hysteresis. A stabilized power output approaching 20% is obtained at the maximum power point. These results shed light on fabricating highly efficient perovskite solar cells via a simple process, and pave the way for solar cell fabrication via scalable methods in the near future.

  17. Dose heterogeneity correction for low-energy brachytherapy sources using dual-energy CT images

    NASA Astrophysics Data System (ADS)

    Mashouf, S.; Lechtman, E.; Lai, P.; Keller, B. M.; Karotki, A.; Beachey, D. J.; Pignol, J. P.

    2014-09-01

    Permanent seed implant brachytherapy is currently used for adjuvant radiotherapy of early stage prostate and breast cancer patients. The current standard for calculation of dose around brachytherapy sources is based on the AAPM TG-43 formalism, which generates the dose in a homogeneous water medium. Recently, AAPM TG-186 emphasized the importance of accounting for tissue heterogeneities. We have previously reported on a methodology where the absorbed dose in tissue can be obtained by multiplying the dose, calculated by the TG-43 formalism, by an inhomogeneity correction factor (ICF). In this work we make use of dual energy CT (DECT) images to extract ICF parameters. The advantage of DECT over conventional CT is that it eliminates the need for tissue segmentation as well as assignment of population based atomic compositions. DECT images of a heterogeneous phantom were acquired and the dose was calculated using both TG-43 and TG-43 × \\text{ICF} formalisms. The results were compared to experimental measurements using Gafchromic films in the mid-plane of the phantom. For a seed implant configuration of 8 seeds spaced 1.5 cm apart in a cubic structure, the gamma passing score for 2%/2 mm criteria improved from 40.8% to 90.5% when ICF was applied to TG-43 dose distributions.

  18. Dose heterogeneity correction for low-energy brachytherapy sources using dual-energy CT images.

    PubMed

    Mashouf, S; Lechtman, E; Lai, P; Keller, B M; Karotki, A; Beachey, D J; Pignol, J P

    2014-09-21

    Permanent seed implant brachytherapy is currently used for adjuvant radiotherapy of early stage prostate and breast cancer patients. The current standard for calculation of dose around brachytherapy sources is based on the AAPM TG-43 formalism, which generates the dose in a homogeneous water medium. Recently, AAPM TG-186 emphasized the importance of accounting for tissue heterogeneities. We have previously reported on a methodology where the absorbed dose in tissue can be obtained by multiplying the dose, calculated by the TG-43 formalism, by an inhomogeneity correction factor (ICF). In this work we make use of dual energy CT (DECT) images to extract ICF parameters. The advantage of DECT over conventional CT is that it eliminates the need for tissue segmentation as well as assignment of population based atomic compositions. DECT images of a heterogeneous phantom were acquired and the dose was calculated using both TG-43 and TG-43 [Formula: see text] formalisms. The results were compared to experimental measurements using Gafchromic films in the mid-plane of the phantom. For a seed implant configuration of 8 seeds spaced 1.5 cm apart in a cubic structure, the gamma passing score for 2%/2 mm criteria improved from 40.8% to 90.5% when ICF was applied to TG-43 dose distributions.

  19. Dual-band optical coherence tomography using a single supercontinuum laser source

    NASA Astrophysics Data System (ADS)

    Chen, Siyu; Shu, Xiao; Yi, Ji; Fawzi, Amani; Zhang, Hao F.

    2016-06-01

    We developed a simultaneous visible-light (Vis) and near-infrared (NIR) dual-band optical coherence tomography (OCT) system using a single supercontinuum laser source. The goal was to benchmark our newly developed Vis-OCT against the well-developed NIR-OCT. The Vis-OCT subsystem operated at 91 nm full-width-at-half-maximum (FWHM) bandwidth centered at 566 nm the NIR-OCT subsystem operated at 93 nm FWHM bandwidth centered at 841 nm. The axial resolutions were 1.8 and 4.4 μm in air for the Vis- and NIR-OCT subsystems, respectively. We compared the respective performances, including anatomical imaging, angiography, absolute retinal blood flow measurements, and spectroscopic analysis for retinal blood oxygen saturation (sO2), between the two subsystems in rodents in vivo. While demonstrating minor discrepancies related to operation wavelengths, both subsystems showed comparable performances in the first three tests. However, we were only able to retrieve sO2 using the Vis-OCT subsystem.

  20. Dual photon absorptiometry using a gadolinium-153 source applied to measure equine bone mineral content

    NASA Astrophysics Data System (ADS)

    Moure, Alessandro; Reichmann, Peter; Remigio Gamba, Humberto

    2003-12-01

    The application of the dual photon absorptiometry (DPA) technique, using gadolinium-153 as the photon source, to evaluate the bone mineral density (BMD) of the third metacarpal bone of horses is presented. The radiation detector was implemented with a NaI(TI) scintillator coupled to a 14 stage photomultiplier. A modular mechanical system allows the position of the prototype to be adjusted in relation to the animal. A moveable carrier makes it possible to scan the third metacarpal with a velocity adjustable between 1 and 12 mm s-1, in steps of 1 mm s-1, for a total distance of 250 mm. The prototype was evaluated with a phantom of the third metacarpal bone made of perspex and aluminium, and in vitro with a transverse slice of the third metacarpal bone of a horse. The tests showed that the prototype has an accuracy and precision of, approximately, 10% and 6%, respectively, for a 6 s acquisition time. Preliminary studies carried out in three foals from birth to one year of age indicated that the prototype is well suited to in vivo and in situ analysis of the BMD of the third metacarpal bones of horses, making it possible to evaluate the changes of BMD levels on a monthly basis. Also, results indicated an exponential behaviour of the BMD curve during the first year of life of the studied horses.

  1. Noise-tolerance analysis for detection and reconstruction of absorbing inhomogeneities with diffuse optical tomography using single- and phase-correlated dual-source schemes

    NASA Astrophysics Data System (ADS)

    Kanmani, B.; Vasu, R. M.

    2007-03-01

    An iterative reconstruction procedure is used to invert intensity data from both single- and phase-correlated dual-source illuminations for absorption inhomogeneities. The Jacobian for the dual source is constructed by an algebraic addition of the Jacobians estimated for the two sources separately. By numerical simulations, it is shown that the dual-source scheme performs superior to the single-source system in regard to (i) noise tolerance in data and (ii) ability to reconstruct smaller and lower contrast objects. The quality of reconstructions from single-source data, as indicated by mean-square error at convergence, is markedly poorer compared to their dual-source counterpart, when noise in data was in excess of 2%. With fixed contrast and decreasing inhomogeneity diameter, our simulations showed that, for diameters below 7 mm, the dual-source scheme has a higher percentage contrast recovery compared to the single-source scheme. Similarly, the dual-source scheme reconstructs to a higher percentage contrast recovery from lower contrast inhomogeneity, in comparison to the single-source scheme.

  2. Virtual monochromatic imaging in dual-source and dual-energy CT for visualization of acute ischemic stroke

    NASA Astrophysics Data System (ADS)

    Hara, Hidetake; Muraishi, Hiroshi; Matsuzawa, Hiroki; Inoue, Toshiyuki; Nakajima, Yasuo; Satoh, Hitoshi; Abe, Shinji

    2015-07-01

    We have recently developed a phantom that simulates acute ischemic stroke. We attempted to visualize an acute-stage cerebral infarction by using dual-energy Computed tomography (DECT) to obtain virtual monochromatic images of this phantom. Virtual monochromatic images were created by using DECT voltages from 40 to 100 keV in steps of 10 keV and from 60 to 80 keV in steps of 1 keV, under three conditions of the tube voltage with thin (Sn) filters. Calculation of the CNR values allowed us to evaluate the visualization of acute-stage cerebral infarction. The CNR value of a virtual monochromatic image was the highest at 68 keV under 80 kV / Sn 140 kV, at 72 keV under 100 kV / Sn 140 kV, and at 67 keV under 140 kV / 80 kV. The CNR values of virtual monochromatic images at voltages between 65 and 75 keV were significantly higher than those obtained for all other created images. Therefore, the optimal conditions for visualizing acute ischemic stroke were achievable.

  3. Feasibility Study of Computational Fluid Dynamics Simulation of Coronary Computed Tomography Angiography Based on Dual-Source Computed Tomography

    PubMed Central

    Lu, Jing; Yu, Jie; Shi, Heshui

    2017-01-01

    Background Adding functional features to morphological features offers a new method for non-invasive assessment of myocardial perfusion. This study aimed to explore technical routes of assessing the left coronary artery pressure gradient, wall shear stress distribution and blood flow velocity distribution, combining three-dimensional coronary model which was based on high resolution dual-source computed tomography (CT) with computational fluid dynamics (CFD) simulation. Methods Three cases of no obvious stenosis, mild stenosis and severe stenosis in left anterior descending (LAD) were enrolled. Images acquired on dual-source CT were input into software Mimics, ICEMCFD and FLUENT to simulate pressure gradient, wall shear stress distribution and blood flow velocity distribution. Measuring coronary enhancement ratio of coronary artery was to compare with pressure gradient. Results Results conformed to theoretical values and showed difference between normal and abnormal samples. Conclusions The study verified essential parameters and basic techniques in blood flow numerical simulation preliminarily. It was proved feasible. PMID:27924174

  4. Initial Experience of the Application of Automated Tube Potential Selection Technique in High-pitch Dual-source CT Angiography of Whole Aorta Using Third-generation Dual-source CT Scanner.

    PubMed

    Kong, Lingyan; Liang, Jixiang; Xue, Huadan; Wang, Yining; Wang, Yun; Jin, Zhengyu; Zhang, Daming; Chen, Jin

    2017-02-20

    Objective To evaluate the application of automated tube potential selection technique in high-pitch dual-source CT aortic angiography on a third-generation dual-source CT scanner. Methods Whole aorta angiography were indiated in 59 patients,who were divided into 2 groups using a simple random method:in group 1 there were 31 patients who underwent the examination with automated tube potential selection using a vascular setting with a preferred image quality of 288 mA/100 kV;in group 2 there were 28 patients who underwent the examination with a tube voltage of 100 kV and automated tube current modulation using a reference tube current of 288 mA. Both groups were scanned on a third generation dual-source CT device operated in dual-source high-pitch ECG-gating mode with a pitch of 3.0,collimation of 2×192×0.6 mm,and a rotation time of 0.25 s. Iterative reconstruction algorithm was used. For group 1,the volume and flow of contrast medium and chasing saline were adapted to the tube voltage. For group 2,a contrast material bolus of 45 ml with a flow of 4.5 ml/s followed by a 50 ml saline chaser at 5 ml/s was used. CTA scan was automatically started using a bolus tracking technique at the level of the original part of aorta after a trigger threshold of 100 HU was reached. The start delay was set to 6 s in both groups. Effective dose (ED),signal to noise ratio (SNR),contrast to noise ratio (CNR),and subjective diagnostic quality of both groups were evaluated. Results The mean ED were 21.3% lower (t=-3.099,P=0.000) in group 1 [(2.48±0.80) mSv] than in group 2 [(3.15±0.86) mSv]. Two groups showed no significant difference in attenuation,SD,SNR,or CNR at all evaluational parts of aorta (ascending aorta,aortic arch,diaphragmatic aorta,or iliac bifurcation)(all P>0.05). There was no significant difference in subjective diagnostic quality values of two groups [(1.41±0.50) scores vs. (1.39±0.50) scores;W=828.5,P=0.837]. Conclusion Compared with automated tube current

  5. Intensity distribution and impact of scatter for dual-source CT

    NASA Astrophysics Data System (ADS)

    Kyriakou, Yiannis; Kalender, Willi A.

    2007-12-01

    Apart from forward scatter, which is given for all CT scanners, dual-source CT (DSCT) is also affected by cross-scatter photons from the second tube-detector system arranged at 90°. We investigated the magnitude and distribution of scatter for DSCT and its impact on image quality. Simulations and measurements of homogeneous and anthropomorphic phantoms were conducted for a DSCT scanner (SOMATOM Definition, Siemens Medical Solutions, Forchheim, Germany) at tube voltages of 80 and 120 kV. The simulations of forward scatter were carried out using combined analytical and Monte Carlo simulation methods for a collimation of 19.2 mm for both tube-detector systems. Measurements of cross scatter were performed by switching one tube off, still reading out the corresponding detector. The relative scatter fractions and the distribution of cross scatter were registered for various imaging conditions. Additionally, a detailed noise analysis with respect to the correction of cross-scatter artifacts is provided to evaluate the performance of correction algorithms. The forward-scatter fraction increased with increasing phantom diameter from 0.02 up to 0.11 for PMMA phantoms of 80 to 400 mm diameter. For cross scatter, the mean intensity was equivalent to forward scatter for small phantoms but was larger for increased phantom size and resulted in severe artifacts in the reconstructed images. The outer dimensions and shape of the object are decisive for the cross-scatter intensity distribution whereas the influence of the degree of inhomogeneity of the respective phantom appears to be negligible. Scatter correction suppressed cross-scatter artifacts but increased noise as a function of the cross-scatter fraction. The magnitude of scatter is not negligible for DSCT systems and dedicated corrections are necessary for the assurance of unimpaired image quality.

  6. Silicon photonic integrated circuit swept-source optical coherence tomography receiver with dual polarization, dual balanced, in-phase and quadrature detection.

    PubMed

    Wang, Zhao; Lee, Hsiang-Chieh; Vermeulen, Diedrik; Chen, Long; Nielsen, Torben; Park, Seo Yeon; Ghaemi, Allan; Swanson, Eric; Doerr, Chris; Fujimoto, James

    2015-07-01

    Optical coherence tomography (OCT) is a widely used three-dimensional (3D) optical imaging method with many biomedical and non-medical applications. Miniaturization, cost reduction, and increased functionality of OCT systems will be critical for future emerging clinical applications. We present a silicon photonic integrated circuit swept-source OCT (SS-OCT) coherent receiver with dual polarization, dual balanced, in-phase and quadrature (IQ) detection. We demonstrate multiple functional capabilities of IQ polarization resolved detection including: complex-conjugate suppressed full-range OCT, polarization diversity detection, and polarization-sensitive OCT. To our knowledge, this is the first demonstration of a silicon photonic integrated receiver for OCT. The integrated coherent receiver provides a miniaturized, low-cost solution for SS-OCT, and is also a key step towards a fully integrated high speed SS-OCT system with good performance and multi-functional capabilities. With further performance improvement and cost reduction, photonic integrated technology promises to greatly increase penetration of OCT systems in existing applications and enable new applications.

  7. Silicon photonic integrated circuit swept-source optical coherence tomography receiver with dual polarization, dual balanced, in-phase and quadrature detection

    PubMed Central

    Wang, Zhao; Lee, Hsiang-Chieh; Vermeulen, Diedrik; Chen, Long; Nielsen, Torben; Park, Seo Yeon; Ghaemi, Allan; Swanson, Eric; Doerr, Chris; Fujimoto, James

    2015-01-01

    Optical coherence tomography (OCT) is a widely used three-dimensional (3D) optical imaging method with many biomedical and non-medical applications. Miniaturization, cost reduction, and increased functionality of OCT systems will be critical for future emerging clinical applications. We present a silicon photonic integrated circuit swept-source OCT (SS-OCT) coherent receiver with dual polarization, dual balanced, in-phase and quadrature (IQ) detection. We demonstrate multiple functional capabilities of IQ polarization resolved detection including: complex-conjugate suppressed full-range OCT, polarization diversity detection, and polarization-sensitive OCT. To our knowledge, this is the first demonstration of a silicon photonic integrated receiver for OCT. The integrated coherent receiver provides a miniaturized, low-cost solution for SS-OCT, and is also a key step towards a fully integrated high speed SS-OCT system with good performance and multi-functional capabilities. With further performance improvement and cost reduction, photonic integrated technology promises to greatly increase penetration of OCT systems in existing applications and enable new applications. PMID:26203382

  8. Applying high frame-rate digital radiography and dual-energy distributed-sources for advanced tomosynthesis

    NASA Astrophysics Data System (ADS)

    Travish, Gil; Rangel, Felix J.; Evans, Mark A.; Schmiedehausen, Kristin

    2013-09-01

    Conventional radiography uses a single point x-ray source with a fan or cone beam to visualize various areas of the human body. An imager records the transmitted photons—historically film and now increasingly digital radiography (DR) flat panel detectors—followed by optional image post-processing. Some post-processing techniques of particular interest are tomosynthesis, and dual energy subtraction. Tomosynthesis adds the ability to recreate quasi-3D images from a series of 2D projections. These exposures are typically taken along an arc or other path; and, tomosynthesis reconstruction is used to form a three-dimensional representation of the area of interest. Dual-energy radiography adds the ability to enhance or "eliminate" structures based on their different attenuation of well-separated end-point energies in two exposures. These advanced capabilities come at a high cost in terms of complexity, imaging time, capital equipment, space, and potentially reduced image quality due to motion blur if acquired sequentially. Recently, the prospect of creating x-ray sources, which are composed of arrays of micro-emitters, has been put forward. These arrays offer a flat-panel geometry and may afford advantages in fabrication methodology, size and cost. They also facilitate the use of the dual energy technology. Here we examine the possibility of using such an array of x-ray sources combined with high frame-rate (~kHz) DR detectors to produce advanced medical images without the need for moving gantries or other complex motion systems. Combining the advantages of dual energy imaging with the ability to determine the relative depth location of anatomical structures or pathological findings from imaging procedures should prove to be a powerful diagnostic tool. We also present use cases that would benefit from the capabilities of this modality.

  9. Radiation dose efficiency of dual-energy CT benchmarked against single-source, kilovoltage-optimized scans

    PubMed Central

    Pratap, Jit

    2016-01-01

    Objective: This study evaluated the radiation dose and image quality implications of dual-energy CT (DECT) use, compared with kilovoltage-optimized single-source/single-energy CT (SECT) on a dual-source Siemens Somatom® Definition Flash CT scanner (Siemens Healthcare, Forcheim, Germany). Methods: With equalized radiation dose (volumetric CT dose index), image noise (standard deviation of CT number) and signal-difference-to-noise ratio (SDNR) were measured and compared across three techniques: 100, 120 and 100/140 kVp (dual energy). Noise in a 30-cm-diameter water phantom and SDNR within unenhanced soft-tissue regions of a small adult (50 kg/165 cm) anthropomorphic phantom were utilized for the assessment. Results: Water phantom image noise decreased with DECT compared with the lower noise SECT setting of 120 kVp (p = 0.046). A decrease in SDNR within the anthropomorphic phantom was demonstrated at 120 kVp compared with the SECT kilovoltage-optimized setting of 100 kVp (p = 0.001). A further decrease in SDNR was observed for the DECT technique when compared with 120 kVp (p = 0.01). Conclusion: On the Siemens Somatom Definition Flash system (Siemens Healthcare), and for equalized radiation dose conditions, image quality expressed as SDNR of unenhanced soft tissue may be compromised for DECT when compared with kilovoltage-optimized SECT, particularly for smaller patients. Advances in knowledge: DECT on a dual-source CT scanner may require a radiation dose increase to maintain unenhanced soft-tissue contrast detectability, particularly for smaller patients. PMID:26559438

  10. Analysis of Pulmonary Vein Antrums Motion with Cardiac Contraction Using Dual-Source Computed Tomography

    PubMed Central

    de Guise, Jacques; Vu, Toni; Chartrand-Lefebvre, Carl; Blais, Danis; Lebeau, Martin; Nguyen, Nhu-Tram; Roberge, David

    2016-01-01

    Purpose: The purpose of the study was to determine the extent of displacement of the pulmonary vein antrums resulting from the intrinsic motion of the heart using 4D cardiac dual-source computed tomography (DSCT). Methods: Ten consecutive female patients were enrolled in this prospective planning study. In breath-hold, a contrast-injected cardiac 4-dimensional (4D) computed tomography (CT) synchronized to the electrocardiogram was obtained using a prospective sequential acquisition method including the extreme phases of systole and diastole. Right and left atrial fibrillation target volumes (CTVR and CTVL) were defined, with each target volume containing the antral regions of the superior and inferior pulmonary veins. Four points of interest were used as surrogates for the right superior and inferior pulmonary vein antrum (RSPVA and RIPVA) and the left superior and inferior pulmonary vein antrum (LSPVA and LIPVA). On our 4D post-processing workstation (MIM Maestro™, MIM Software Inc.), maximum displacement of each point of interest from diastole to systole was measured in the mediolateral (ML), anteroposterior (AP), and superoinferior (SI) directions. Results: Median age of the enrolled patients was 60 years (range, 56-71 years). Within the CTVR, the mean displacements of the superior and inferior surrogates were 3 mm vs. 1 mm (p=0.002), 2 mm vs. 0 mm (p= 0.001), and 3 mm vs. 0 mm (p=0.00001), in the ML, AP, and SI directions, respectively. On the left, mean absolute displacements of the LSPVA vs. LIPVA were similar at 4 mm vs. 1 mm (p=0.0008), 2 mm vs. 0 mm (p= 0.001), and 3 mm vs. 1 mm (p=0.00001) in the ML, AP, and SI directions. Conclusion: When isolated from breathing, cardiac contraction is associated with minimal inferior pulmonary veins motion and modest (1-6 mm) motion of the superior veins. Target deformation was thus of a magnitude similar or greater than target motion, limiting the potential gains of cardiac tracking. Optimal strategies for cardiac

  11. Robust image transmission using a new joint source channel coding algorithm and dual adaptive OFDM

    NASA Astrophysics Data System (ADS)

    Farshchian, Masoud; Cho, Sungdae; Pearlman, William A.

    2004-01-01

    In this paper we consider the problem of robust image coding and packetization for the purpose of communications over slow fading frequency selective channels and channels with a shaped spectrum like those of digital subscribe lines (DSL). Towards this end, a novel and analytically based joint source channel coding (JSCC) algorithm to assign unequal error protection is presented. Under a block budget constraint, the image bitstream is de-multiplexed into two classes with different error responses. The algorithm assigns unequal error protection (UEP) in a way to minimize the expected mean square error (MSE) at the receiver while minimizing the probability of catastrophic failure. In order to minimize the expected mean square error at the receiver, the algorithm assigns unequal protection to the value bit class (VBC) stream. In order to minimizes the probability of catastrophic error which is a characteristic of progressive image coders, the algorithm assigns more protection to the location bit class (LBC) stream than the VBC stream. Besides having the advantage of being analytical and also numerically solvable, the algorithm is based on a new formula developed to estimate the distortion rate (D-R) curve for the VBC portion of SPIHT. The major advantage of our technique is that the worst case instantaneous minimum peak signal to noise ratio (PSNR) does not differ greatly from the averge MSE while this is not the case for the optimal single stream (UEP) system. Although both average PSNR of our method and the optimal single stream UEP are about the same, our scheme does not suffer erratic behavior because we have made the probability of catastrophic error arbitarily small. The coded image is sent via orthogonal frequency division multiplexing (OFDM) which is a known and increasing popular modulation scheme to combat ISI (Inter Symbol Interference) and impulsive noise. Using dual adaptive energy OFDM, we use the minimum energy necessary to send each bit stream at a

  12. Impact on Image Quality and Radiation Dose of Third-Generation Dual-Source Computed Tomography of the Coronary Arteries.

    PubMed

    Apfaltrer, Georg; Szolar, Dieter H; Wurzinger, Eric; Takx, Richard A P; Nance, John W; Dutschke, Anja; Tschauner, Sebastian; Loewe, Christian; Ringl, Helmut; Sorantin, Erich; Apfaltrer, Paul

    2017-04-15

    The aim of this study was to assess the image quality (IQ) and radiation dose of third-generation dual-source computed tomography (CT) coronary angiography (cCTA) in comparison with 64-slice single-source CT. This retrospective study included 140 patients (73 men, mean age 62 ± 11 years) with low-to-intermediate probability of coronary artery disease who underwent either third-generation dual-source cCTA using prospectively electrocardiography-triggered high-pitch spiral acquisition (n = 70) (group 1) or retrospective electrocardiography-gated cCTA on a 64-slice CT system (n = 70) (group 2). Contrast-to-noise and signal-to-noise ratios were measured within the aorta and coronary arteries. Subjective IQ was assessed using a 5-point Likert scale. Effective dose was estimated using specific conversion factors. The contrast-to-noise ratio of group 1 was significantly higher than group 2 at all levels (all p <0.001). Signal-to-noise ratio of group 1 was also significantly higher than group 2 (p <0.05), except for the distal left circumflex artery. Subjective IQ for group 1 was rated significantly better than for group 2 (median score [25th to 75th percentile]: 1 [1 to 2] vs 2 [2 to 3]; p <0.001). The median effective dose was 1.55 mSv (1.09 to 1.88) in group 1 versus 12.29 mSv (11.63 to 14.36) in group 2 (p <0.001) which corresponds to a mean radiation dose reduction of 87.4%. In conclusion, implementation of third-generation dual-source CT system for cCTA leads to improved IQ with significant radiation dose savings.

  13. The Source of Execution-Related Dual-Task Interference: Motor Bottleneck or Response Monitoring?

    ERIC Educational Resources Information Center

    Bratzke, Daniel; Rolke, Bettina; Ulrich, Rolf

    2009-01-01

    The present study assessed the underlying mechanism of execution-related dual-task interference in the psychological refractory period (PRP) paradigm. The motor bottleneck hypothesis attributes this interference to a processing limitation at the motor level. By contrast, the response monitoring hypothesis attributes it to a bottleneck process that…

  14. Dual-source dual-energy CT with additional tin filtration: Dose and image quality evaluation in phantoms and in-vivo

    PubMed Central

    Primak, Andrew N.; Giraldo, Juan Carlos Ramirez; Eusemann, Christian D.; Schmidt, Bernhard; Kantor, B.; Fletcher, Joel G.; McCollough, Cynthia H.

    2010-01-01

    Purpose To investigate the effect on radiation dose and image quality of the use of additional spectral filtration for dual-energy CT (DECT) imaging using dual-source CT (DSCT). Materials and Methods A commercial DSCT scanner was modified by adding tin filtration to the high-kV tube, and radiation output and noise measured in water phantoms. Dose values for equivalent image noise were compared among DE-modes with and without tin filtration and single-energy (SE) mode. To evaluate DECT material discrimination, the material-specific DEratio for calcium and iodine were determined using images of anthropomorphic phantoms. Data were additionally acquired in 38 and 87 kg pigs, and noise for the linearly mixed and virtual non-contrast (VNC) images compared between DE-modes. Finally, abdominal DECT images from two patients of similar sizes undergoing clinically-indicated CT were compared. Results Adding tin filtration to the high-kV tube improved the DE contrast between iodine and calcium as much as 290%. Pig data showed that the tin filtration had no effect on noise in the DECT mixed images, but decreased noise by as much as 30% in the VNC images. Patient VNC-images acquired using 100/140 kV with added tin filtration had improved image quality compared to those generated with 80/140 kV without tin filtration. Conclusion Tin filtration of the high-kV tube of a DSCT scanner increases the ability of DECT to discriminate between calcium and iodine, without increasing dose relative to SECT. Furthermore, use of 100/140 kV tube potentials allows improved DECT imaging of large patients. PMID:20966323

  15. Heat Source/Sink in a Magneto-Hydrodynamic Non-Newtonian Fluid Flow in a Porous Medium: Dual Solutions.

    PubMed

    Hayat, Tasawar; Awais, Muhammad; Imtiaz, Amna

    2016-01-01

    This communication deals with the properties of heat source/sink in a magneto-hydrodynamic flow of a non-Newtonian fluid immersed in a porous medium. Shrinking phenomenon along with the permeability of the wall is considered. Mathematical modelling is performed to convert the considered physical process into set of coupled nonlinear mathematical equations. Suitable transformations are invoked to convert the set of partial differential equations into nonlinear ordinary differential equations which are tackled numerically for the solution computations. It is noted that dual solutions for various physical parameters exist which are analyzed in detail.

  16. Plug-and-play Integration of dual-model based Knowledge Artefacts into an Open Source Ehr System.

    PubMed

    Krexner, Rabea; Duftschmid, Georg

    2014-01-01

    In this paper we present our experiences with extending an existing approach for an archetype-compliant collection and export of data according to the openEHR specifications within the open source EHR system OpenMRS. It allows an automatic generation of forms from templates, which were introduced by openEHR as an extension of the dual-model approach. Data entered in these forms can be exported in form of standardized EHR extracts. The use of templates allowed us to solve problems reported for the original archetype-based version of the approach, which were caused by the high optionality within archetypes.

  17. Heat Source/Sink in a Magneto-Hydrodynamic Non-Newtonian Fluid Flow in a Porous Medium: Dual Solutions

    PubMed Central

    Hayat, Tasawar; Awais, Muhammad; Imtiaz, Amna

    2016-01-01

    This communication deals with the properties of heat source/sink in a magneto-hydrodynamic flow of a non-Newtonian fluid immersed in a porous medium. Shrinking phenomenon along with the permeability of the wall is considered. Mathematical modelling is performed to convert the considered physical process into set of coupled nonlinear mathematical equations. Suitable transformations are invoked to convert the set of partial differential equations into nonlinear ordinary differential equations which are tackled numerically for the solution computations. It is noted that dual solutions for various physical parameters exist which are analyzed in detail. PMID:27598314

  18. Image reconstruction and image quality evaluation for a dual source CT scanner

    PubMed Central

    Flohr, T. G.; Bruder, H.; Stierstorfer, K.; Petersilka, M.; Schmidt, B.; McCollough, C. H.

    2008-01-01

    The authors present and evaluate concepts for image reconstruction in dual source CT (DSCT). They describe both standard spiral (helical) DSCT image reconstruction and electrocardiogram (ECG)-synchronized image reconstruction. For a compact mechanical design of the DSCT, one detector (A) can cover the full scan field of view, while the other detector (B) has to be restricted to a smaller, central field of view. The authors develop an algorithm for scan data completion, extrapolating truncated data of detector (B) by using data of detector (A). They propose a unified framework for convolution and simultaneous 3D backprojection of both (A) and (B) data, with similar treatment of standard spiral, ECG-gated spiral, and sequential (axial) scan data. In ECG-synchronized image reconstruction, a flexible scan data range per measurement system can be used to trade off temporal resolution for reduced image noise. Both data extrapolation and image reconstruction are evaluated by means of computer simulated data of anthropomorphic phantoms, by phantom measurements and patient studies. The authors show that a consistent filter direction along the spiral tangent on both detectors is essential to reduce cone-beam artifacts, requiring truncation of the extrapolated (B) data after convolution in standard spiral scans. Reconstructions of an anthropomorphic thorax phantom demonstrate good image quality and dose accumulation as theoretically expected for simultaneous 3D backprojection of the filtered (A) data and the truncated filtered (B) data into the same 3D image volume. In ECG-gated spiral modes, spiral slice sensitivity profiles (SSPs) show only minor dependence on the patient’s heart rate if the spiral pitch is properly adapted. Measurements with a thin gold plate phantom result in effective slice widths (full width at half maximum of the SSP) of 0.63–0.69mm for the nominal 0.6mm slice and 0.82–0.87mm for the nominal 0.75mm slice. The visually determined through-plane (z

  19. A diode-pumped Nd:YAlO3 dual-wavelength yellow light source

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Fu, Xihong; Zhai, Pei; Xia, Jing; Li, Shutao

    2013-11-01

    We present what is, to the best of our knowledge, the first diode-pumped Nd:YAlO3 (Nd:YAP) continuous-wave (cw) dual-wavelength yellow laser at 593 nm and 598 nm, based on sum-frequency generation between 1064 and 1339 nm in a-axis polarization using LBO crystal and between 1079 and 1341 nm in c-axis polarization using PPKTP crystal, respectively. At an incident pump power of 17.3 W, the maximum output power obtained at 593 nm and 598 nm is 0.18 W and 1.86 W, respectively. The laser experiment shows that Nd:YAP crystal can be used for an efficient diode-pumped dual-wavelength yellow laser system.

  20. A 2.45 GHz electron cyclotron resonance proton ion source and a dual-lens low energy beam transporta)

    NASA Astrophysics Data System (ADS)

    Zhang, W. H.; Ma, H. Y.; Yang, Y.; Wu, Q.; Zhang, X. Z.; Wang, H.; Ma, B. H.; Feng, Y. C.; Fang, X.; Guo, J. W.; Cao, Y.; Li, X. X.; Zhu, Y. H.; Li, J. Y.; Sha, S.; Lu, W.; Lin, S. H.; Guo, X. H.; Zhao, H. Y.; Sun, L. T.; Xie, D. Z.; Peng, S. X.; Liu, Z. W.; Zhao, H. W.

    2012-02-01

    The structure and preliminary commissioning results of a new 2.45 GHz ECR proton ion source and a dual-lens low energy beam transport (LEBT) system are presented in this paper. The main magnetic field of the ion source is provided by a set of permanent magnets with two small electro-solenoid magnets at the injection and the extraction to fine tune the magnetic field for better microwave coupling. A 50 keV pulsed proton beam extracted by a three-electrode mechanism passes through the LEBT system of length of 1183 mm. This LEBT consists of a diagnosis chamber, two Glaser lenses, two steering magnets, and a final beam defining cone. A set of inner permanent magnetic rings is embedded in each of the two Glaser lenses to produce a flatter axial-field to reduce the lens aberrations.

  1. A 2.45 GHz electron cyclotron resonance proton ion source and a dual-lens low energy beam transport

    SciTech Connect

    Zhang, W. H.; Ma, H. Y.; Wu, Q.; Zhang, X. Z.; Wang, H.; Ma, B. H.; Feng, Y. C.; Fang, X.; Guo, J. W.; Li, X. X.; Zhu, Y. H.; Li, J. Y.; Guo, X. H.; Zhao, H. Y.; Sun, L. T.; Xie, D. Z.; Liu, Z. W.; Zhao, H. W.; Yang, Y.; Cao, Y.; and others

    2012-02-15

    The structure and preliminary commissioning results of a new 2.45 GHz ECR proton ion source and a dual-lens low energy beam transport (LEBT) system are presented in this paper. The main magnetic field of the ion source is provided by a set of permanent magnets with two small electro-solenoid magnets at the injection and the extraction to fine tune the magnetic field for better microwave coupling. A 50 keV pulsed proton beam extracted by a three-electrode mechanism passes through the LEBT system of length of 1183 mm. This LEBT consists of a diagnosis chamber, two Glaser lenses, two steering magnets, and a final beam defining cone. A set of inner permanent magnetic rings is embedded in each of the two Glaser lenses to produce a flatter axial-field to reduce the lens aberrations.

  2. Fire Source Localization Based on Distributed Temperature Sensing by a Dual-Line Optical Fiber System

    PubMed Central

    Sun, Miao; Tang, Yuquan; Yang, Shuang; Li, Jun; Sigrist, Markus W.; Dong, Fengzhong

    2016-01-01

    We propose a method for localizing a fire source using an optical fiber distributed temperature sensor system. A section of two parallel optical fibers employed as the sensing element is installed near the ceiling of a closed room in which the fire source is located. By measuring the temperature of hot air flows, the problem of three-dimensional fire source localization is transformed to two dimensions. The method of the source location is verified with experiments using burning alcohol as fire source, and it is demonstrated that the method represents a robust and reliable technique for localizing a fire source also for long sensing ranges. PMID:27275822

  3. Fire Source Localization Based on Distributed Temperature Sensing by a Dual-Line Optical Fiber System.

    PubMed

    Sun, Miao; Tang, Yuquan; Yang, Shuang; Li, Jun; Sigrist, Markus W; Dong, Fengzhong

    2016-06-06

    We propose a method for localizing a fire source using an optical fiber distributed temperature sensor system. A section of two parallel optical fibers employed as the sensing element is installed near the ceiling of a closed room in which the fire source is located. By measuring the temperature of hot air flows, the problem of three-dimensional fire source localization is transformed to two dimensions. The method of the source location is verified with experiments using burning alcohol as fire source, and it is demonstrated that the method represents a robust and reliable technique for localizing a fire source also for long sensing ranges.

  4. Nitrate source apportionment using a combined dual isotope, chemical and bacterial property, and Bayesian model approach in river systems

    NASA Astrophysics Data System (ADS)

    Xia, Yongqiu; Li, Yuefei; Zhang, Xinyu; Yan, Xiaoyuan

    2017-01-01

    Nitrate (NO3-) pollution is a serious problem worldwide, particularly in countries with intensive agricultural and population activities. Previous studies have used δ15N-NO3- and δ18O-NO3- to determine the NO3- sources in rivers. However, this approach is subject to substantial uncertainties and limitations because of the numerous NO3- sources, the wide isotopic ranges, and the existing isotopic fractionations. In this study, we outline a combined procedure for improving the determination of NO3- sources in a paddy agriculture-urban gradient watershed in eastern China. First, the main sources of NO3- in the Qinhuai River were examined by the dual-isotope biplot approach, in which we narrowed the isotope ranges using site-specific isotopic results. Next, the bacterial groups and chemical properties of the river water were analyzed to verify these sources. Finally, we introduced a Bayesian model to apportion the spatiotemporal variations of the NO3- sources. Denitrification was first incorporated into the Bayesian model because denitrification plays an important role in the nitrogen pathway. The results showed that fertilizer contributed large amounts of NO3- to the surface water in traditional agricultural regions, whereas manure effluents were the dominant NO3- source in intensified agricultural regions, especially during the wet seasons. Sewage effluents were important in all three land uses and exhibited great differences between the dry season and the wet season. This combined analysis quantitatively delineates the proportion of NO3- sources from paddy agriculture to urban river water for both dry and wet seasons and incorporates isotopic fractionation and uncertainties in the source compositions.

  5. Recognition Memory zROC Slopes for Items with Correct versus Incorrect Source Decisions Discriminate the Dual Process and Unequal Variance Signal Detection Models

    ERIC Educational Resources Information Center

    Starns, Jeffrey J.; Rotello, Caren M.; Hautus, Michael J.

    2014-01-01

    We tested the dual process and unequal variance signal detection models by jointly modeling recognition and source confidence ratings. The 2 approaches make unique predictions for the slope of the recognition memory zROC function for items with correct versus incorrect source decisions. The standard bivariate Gaussian version of the unequal…

  6. Comparison of three dual-source remote sensing evapotranspiration models during the MUSOEXE-12 campaign: Revisit of model physics

    NASA Astrophysics Data System (ADS)

    Yang, Yuting; Long, Di; Guan, Huade; Liang, Wei; Simmons, Craig; Batelaan, Okke

    2015-05-01

    Various remote sensing-based terrestrial evapotranspiration (ET) models have been developed during the past four decades. These models vary in conceptual and mathematical representations of the physics, consequently leading to different performances. Examination of uncertainties associated with limitations in model physics will be useful for model selection and improvement. Here, three dual-source remote sensing ET models (i.e., the Hybrid dual-source scheme and Trapezoid framework-based ET Model (HTEM), the Two-Source Energy Balance (TSEB) model, and the MOD16 ET algorithm) using ASTER images were compared during the MUSOEXE-12 campaign in the Heihe River Basin in Northwest China, aiming to better understand the differences in model physics that potentially lead to differences in model performance. Model results were first compared against observations from a dense network of eddy covariance towers and isotope-based evaporation (E) and transpiration (T) partitioning. Results show that HTEM outperformed the other two models in simulating ET and its partitioning, whereas MOD16 performed worst (i.e., ET root-mean-square errors are 42.3 W/m2 (HTEM), 49.8 W/m2 (TSEB), and 95.3 W/m2 (MOD16)). On to model limitations, HTEM tends to underestimate ET under high advection due mostly to the underestimation of temperatures for the wet edge in its trapezoidal space. For TSEB, large uncertainties occur in determining the initial Priestley-Taylor coefficient and the iteration procedure for ET partitioning, leading to overestimation/underestimation of T/E in most cases, particularly over sparse vegetation. Primary use of meteorological data for MOD16 does not effectively capture the soil moisture restriction on ET, and therefore results in unreasonable spatial ET patterns.

  7. Dual-source RF transmission in cardiac SSFP imaging at 3 T: systematic spatial evaluation of image quality improvement compared to conventional RF transmission.

    PubMed

    Rasper, Michael; Gramer, Bettina M; Settles, Marcus; Laugwitz, Karl-Ludwig; Ibrahim, Tareq; Rummeny, Ernst J; Huber, Armin

    2015-01-01

    The purpose of this investigation was to systematically evaluate the spatial distribution of image quality improvement with dual-source radiofrequency (RF) transmission in cardiac steady-state free precession sequences at 3.0 T. Imaging with and without dual-source RF transmission was performed in 30 patients. Contrast-to-noise ratio for the left ventricular myocardium was significantly higher using dual-source RF transmission, but improvement was not uniformly distributed. The posterior myocardium showed significantly less contrast-to-noise ratio gain than all other cardiac regions. Signal-to-noise ratio increase was higher in the right than in the left ventricle. Subjective image quality was significantly enhanced by parallel RF transmission.

  8. Effectiveness of Using Dual-source CT and the Upshot it creates on Both Heart Rate and Image Quality

    PubMed Central

    Selçuk, Tuba; Otçu, Hafize; Yüceler, Zeyneb; Bilgili, Çiğdem; Bulakçı, Mesut; Savaş, Yıldıray; Çelik, Ömer

    2016-01-01

    Background: Early detection of coronary artery disease (CAD) is important because of the high morbidity and mortality rates. As invasive coronary angiography (ICA) is an invasive procedure, an alternative diagnostic method; coronary computed tomography angiography (CTA), has become more widely used by the improvements in detector technology. Aims: In this study, we aimed to examine the accuracy and image quality of high-pitch 128-slice dual-source CTA taking the ICA as reference technique. We also aimed to compare the accuracy and image quality between different heart rate groups of >70 beates per minute (bpm) and ≤70 bpm. Study Design: Retrospective cross-sectional study. Methods: Among 450 patients who underwent coronary CTA with the FLASH spiral technique, performed with a second generation dual-source computed tomography device with a pitch value of 3.2, 102 patients without stent and/or bypass surgery history and clinically suspected coronary artery disease who underwent ICA within 15 days were enrolled. Image quality was assessed by two independent radiologists using a 4-point scale (1=absence of any artifacts- 4=non-evaluable). A stenosis >50% was considered significant on a per-segment, per-vessel, and per-patient basis and ICA was considered the reference method. Radiation doses were determined using dose length product (DLP) values detected by the computed tomography (CT) device. In addition, patients were classified into two groups according to their heart rates as ≤70 bpm (73 patients) and >70 bpm (29 patients). The relation between the diagnostic accuracy and heart rate groups were evaluated. Results: Overall, 1495 (98%) coronary segments were diagnostic in 102 patients (32 male, 70 female, mean heart rate: 65 bpm). There was a significant correlation between image quality and mean heart rate in the right coronary artery (RCA) segments. The effective radiation dose was 0.98±0.09 mili Sievert (mSv). On a per-patient basis, sensitivity, specificity

  9. Emission sources and atmospheric processing of carbonaceous aerosols in India and China: Insights from dual carbon isotope techniques

    NASA Astrophysics Data System (ADS)

    Andersson, A.; Kirillova, E. N.; Bosch, C.; Suresh, T.; Lee, M.; Du, K.; Sheesley, R. J.; Budhavant, K.; Gustafsson, O. M.

    2013-12-01

    The large emissions of carbonaceous aerosols, e.g., black carbon (BC), in India and China have detrimental effects on both human health and the regional climate. However, mitigation efforts as well as accurate modeling of these effects are currently hampered by large uncertainties regarding the contributions from different emission sources, including both primary and secondary processes. Here, we present dual carbon isotope constraints on emissions sources and atmospheric processing from multiple sites capturing the outflow from India and China. Radiocarbon (14C) studies of elemental carbon (EC) - a tracer for BC - show larger relative fossil contributions than expected from bottom-up emission inventories, for both India (49+-5) and China (80 +-6%). Similarly to EC, radiocarbon constraints of water soluble organic carbon (WSOC) shows substantially larger relative fossil contributions in Chinese outflow (30-50%) as compared with India, but also compared to Europe and USA (10-20%). In contrast to the radiocarbon data, stable carbon (d13C) analysis of WSOC shows substantial variability for different sites capturing the Indian outflow. Strong enrichment of heavy isotopes in WSOC is coupled to expected transport time from sources, indicating the influence of photochemical aging during transport. Such trends in the d13C signature are not observed for the EC fraction. Taken together this work show that carbon isotope techniques provide firm constraints on emission sources of different fractions of carbonaceous aerosols, and may also offer insights into atmospheric processing of these constituents during air mass transport.

  10. Utilization of dual-source X-ray tomography for reduction of scanning time of wooden samples

    NASA Astrophysics Data System (ADS)

    Fíla, T.; Kumpová, I.; Jandejsek, I.; Kloiber, M.; Tureček, D.; Vavřík, D.

    2015-05-01

    We present a novel dual-source/dual energy (DSCT/DECT) micro-tomography system including results of high-resolution DSCT reconstruction. The DSCT micro-tomography setup was designed as a multi-purpose X-ray imaging device equipped with two pairs of X-ray tubes and detectors in orthogonal arrangement with independent control of beam parameters. Both pairs (tube-detector) are mounted on a computer numerical control positioning system and can be independently set up to different geometries (e.g. with different magnification of each pair). In this work the simultaneous scanning of the object by two tube-detector pairs was used for approximately half reduction of tomography scanning time. The developed imaging procedure was applied for scanning of a wooden sample locally damaged during a semi-destructive test for assessment of wood quality. Prior to the tomography measurements the setup geometry was precisely adjusted in terms of magnification, horizontal and vertical tube-specimen-detector alignment of both pairs. DSCT measurements were carried out in sequence (2 × 90° for each tube) with identical 100μm image resolution. It was proven that the presented experimental setup combined with appropriate control technique significantly reduces tomography scanning time of materials with complex micro-structure.

  11. Controllable time dependent and dual band emission infrared source to test missile warning systems in flight

    NASA Astrophysics Data System (ADS)

    Cabib, Dario; Davidzon, Larry; Gil, Amir

    2008-10-01

    Proliferation and technological progress of Mid Wave Infrared (MWIR) sensors for Missile Warning Systems (MWS)1,2 and increased sophistication of countermeasures require demanding in-flight testing. The IR sensors are becoming more sensitive for longer range of detection, the spatial resolution is improving for better target detection and identification, spectral discrimination is being introduced for lower False Alarm Rate (FAR), and the imaging frame rate is increasing for faster defensive reaction. As a result, testing a complex MWS/countermeasure system performance before deployment requires ever more realistic simulation of the threats in their natural backgrounds, and faster measurement of the radiometric output, directionality and time response of the countermeasures. In a previous paper3 we have described a system (IRTS or Infrared Threat Stimulator) we developed to test missile warning systems (MWS) mounted on an aircraft. The IRTS is placed in the field and projects a time dependent infrared beam toward the flying aircraft. The time dependent intensity of the beam simulates the infrared emittance of an approaching missile in the 3 to 5 micron spectral range as sensed by an MWS system. Now we have developed a new system based on the IRTS concept allowing the user to separately control the time profiles of two different infrared ranges independently within the 3 to 5 micron range. This is important because MWS instrumentation now has higher spectral discrimination capability in order to be more missile-specific and less prone to be confused by clutter and background signals. In this paper we describe the new dual band IRTS system and its capability (or Dual Color IRTS, DCIRTS).

  12. Dual Nitrate Isotopes in Dry Deposition: Utility for Partitioning Nox Source Contributions to Landscape Nitrogen Deposition

    EPA Science Inventory

    Dry deposition is a major component of total nitrogen deposition and thus an important source of bioavailable nitrogen to ecosystems. However, relative to wet deposition, less is known regarding the sources and spatial variability of dry deposition. This is in part due to diffi...

  13. Enhancing Competition through the Improvement of the Dual Sourcing Decision Criteria at the Aeronautical Systems Division

    DTIC Science & Technology

    1986-09-01

    Transfer of Production Technology Adequacy of TDP Data Rights Contractor Investment Learning Curve Technical Assistance need by second source Maintenance... transfer of production expertise involves 26 people. Even with a good TDP, people are needed to augment the start up of a second source. The degree

  14. Dual isotope notch observer for isotope identification, assay and imaging with mono-energetic gamma-ray sources

    DOEpatents

    Barty, Christopher P.J.

    2013-02-05

    A dual isotope notch observer for isotope identification, assay and imaging with mono-energetic gamma-ray sources includes a detector arrangement consists of three detectors downstream from the object under observation. The latter detector, which operates as a beam monitor, is an integrating detector that monitors the total beam power arriving at its surface. The first detector and the middle detector each include an integrating detector surrounding a foil. The foils of these two detectors are made of the same atomic material, but each foil is a different isotope, e.g., the first foil may comprise U235 and second foil may comprise U238. The integrating detectors surrounding these pieces of foil measure the total power scattered from the foil and can be similar in composition to the final beam monitor. Non-resonant photons will, after calibration, scatter equally from both foils.

  15. A tunable dual-wavelength pump source based on simulated polariton scattering for terahertz-wave generation

    NASA Astrophysics Data System (ADS)

    Sun, Bo; Liu, Jinsong; Yao, Jianquan; Li, Enbang

    2013-11-01

    We propose a dual-wavelength pump source by utilizing stimulated polariton scattering in a LiNbO3 crystal. The residual pump and the generated tunable Stokes waves can be combined to generate THz-wave generation via difference frequency generation (DFG). With a pump energy of 49 mJ, Stokes waves with a tuning range from 1067.8 to 1074 nm have been generated, and an output energy of up to 14.9 mJ at 1070 nm has been achieved with a conversion efficiency of 21.7%. A sum frequency generation experiment was carried out to demonstrate the feasibility of the proposed scheme for THz-wave DFG.

  16. Automatic selection of an optimal systolic and diastolic reconstruction windows for dual-source CT coronary angiography

    NASA Astrophysics Data System (ADS)

    Seifarth, H.; Puesken, M.; Wienbeck, S.; Maintz, D.; Heindel, W.; Juergens, K.-U.

    2008-03-01

    Purpose: To assess the performance of a motion map algorithm to automatically determine the optimal systolic and diastolic reconstruction window for coronary CT Angiography using Dual Source CT. Materials and Methods: Dual Source coronary CT angiography data sets (Somatom Definition, Siemens Medical Solutions) from 50 consecutive patients were included in the analysis. Optimal systolic and diastolic reconstruction windows were determined using a motion map algorithm (BestPhase, Siemens Medical Solutions). Additionally data sets were reconstructed in 5% steps throughout the RR-interval. For each major vessel (RCA, LAD and LCX) an optimal systolic and diastolic reconstruction window was manually determined by two independent readers using volume rendering displays. Image quality was rated using a five-point scale (1 = no motion artifacts, 5 = severe motion artifacts over entire length of the vessel). Results: The mean heart rate during the scan was 72.4bpm (+/-15.8bpm). Median systolic and diastolic reconstruction windows using the BestPhase algorithm were at 37% and 73% RR. The median manually selected systolic reconstruction window was 35 %, 30% and 35% for RCA, LAD, and LCX. For all vessels the median observer selected diastolic reconstruction window was 75%. Mean image quality using the BestPhase algorithm was 2.4 +/-0.9 for systolic reconstructions and 1.9 +/-1.1 for diastolic reconstructions. Using the manual approach, the mean image quality was 1.9 +/-0.5 and 1.7 +/-0.8 respectively. There was a significant difference in image quality between automatically and manually determined systolic reconstructions (p<0.01) but there was no significant difference in image quality in diastolic reconstructions. Conclusion: Automatic determination of the optimal reconstruction interval using the BestPhase algorithm is feasible and yields reconstruction windows similar to observer selected reconstruction windows. In diastolic reconstructions overall image quality is similar

  17. Modeling of single event transients with dual double-exponential current sources: Implications for logic cell characterization

    SciTech Connect

    Black, Dolores Archuleta; Robinson, William H.; Wilcox, Ian Zachary; Limbrick, Daniel B.; Black, Jeffrey D.

    2015-08-07

    Single event effects (SEE) are a reliability concern for modern microelectronics. Bit corruptions can be caused by single event upsets (SEUs) in the storage cells or by sampling single event transients (SETs) from a logic path. Likewise, an accurate prediction of soft error susceptibility from SETs requires good models to convert collected charge into compact descriptions of the current injection process. This paper describes a simple, yet effective, method to model the current waveform resulting from a charge collection event for SET circuit simulations. The model uses two double-exponential current sources in parallel, and the results illustrate why a conventional model based on one double-exponential source can be incomplete. Furthermore, a small set of logic cells with varying input conditions, drive strength, and output loading are simulated to extract the parameters for the dual double-exponential current sources. As a result, the parameters are based upon both the node capacitance and the restoring current (i.e., drive strength) of the logic cell.

  18. Modeling of single event transients with dual double-exponential current sources: Implications for logic cell characterization

    DOE PAGES

    Black, Dolores Archuleta; Robinson, William H.; Wilcox, Ian Zachary; ...

    2015-08-07

    Single event effects (SEE) are a reliability concern for modern microelectronics. Bit corruptions can be caused by single event upsets (SEUs) in the storage cells or by sampling single event transients (SETs) from a logic path. Likewise, an accurate prediction of soft error susceptibility from SETs requires good models to convert collected charge into compact descriptions of the current injection process. This paper describes a simple, yet effective, method to model the current waveform resulting from a charge collection event for SET circuit simulations. The model uses two double-exponential current sources in parallel, and the results illustrate why a conventionalmore » model based on one double-exponential source can be incomplete. Furthermore, a small set of logic cells with varying input conditions, drive strength, and output loading are simulated to extract the parameters for the dual double-exponential current sources. As a result, the parameters are based upon both the node capacitance and the restoring current (i.e., drive strength) of the logic cell.« less

  19. A dual neutron/gamma source for the Fissmat Inspection for Nuclear Detection (FIND) system.

    SciTech Connect

    Doyle, Barney Lee; King, Michael; Rossi, Paolo; McDaniel, Floyd Del; Morse, Daniel Henry; Antolak, Arlyn J.; Provencio, Paula Polyak; Raber, Thomas N.

    2008-12-01

    Shielded special nuclear material (SNM) is very difficult to detect and new technologies are needed to clear alarms and verify the presence of SNM. High-energy photons and neutrons can be used to actively interrogate for heavily shielded SNM, such as highly enriched uranium (HEU), since neutrons can penetrate gamma-ray shielding and gamma-rays can penetrate neutron shielding. Both source particles then induce unique detectable signals from fission. In this LDRD, we explored a new type of interrogation source that uses low-energy proton- or deuteron-induced nuclear reactions to generate high fluxes of mono-energetic gammas or neutrons. Accelerator-based experiments, computational studies, and prototype source tests were performed to obtain a better understanding of (1) the flux requirements, (2) fission-induced signals, background, and interferences, and (3) operational performance of the source. The results of this research led to the development and testing of an axial-type gamma tube source and the design/construction of a high power coaxial-type gamma generator based on the {sup 11}B(p,{gamma}){sup 12}C nuclear reaction.

  20. Dual-Carbon sources fuel the OCS deep-reef Community, a stable isotope investigation

    USGS Publications Warehouse

    Sulak, Kenneth J.; Berg, J.; Randall, Michael; Dennis, George D.; Brooks, R.A.

    2008-01-01

    The hypothesis that phytoplankton is the sole carbon source for the OCS deep-reef community (>60 m) was tested. Trophic structure for NE Gulf of Mexico deep reefs was analyzed via carbon and nitrogen stable isotopes. Carbon signatures for 114 entities (carbon sources, sediment, fishes, and invertebrates) supported surface phytoplankton as the primary fuel for the deep reef. However, a second carbon source, the macroalga Sargassum, with its epiphytic macroalgal associate, Cladophora liniformis, was also identified. Macroalgal carbon signatures were detected among 23 consumer entities. Most notably, macroalgae contributed 45 % of total carbon to the 13C isotopic spectrum of the particulate-feeding reef-crest gorgonian Nicella. The discontinuous spatial distribution of some sessile deep-reef invertebrates utilizing pelagic macroalgal carbon may be trophically tied to the contagious distribution of Sargassum biomass along major ocean surface features.

  1. Numerical simulation of a dual-source supersonic plasma jet expansion process: continuum approach

    NASA Astrophysics Data System (ADS)

    Pal, Subrata; Dey, Subhrajit; Miebach, Thomas

    2007-05-01

    Expanding thermal plasma (ETP) is a versatile technology for thin film deposition process with directional plasma flux and high deposition rates. This process involves expansion of supersonic plasma jets through a steep pressure ratio into a chamber maintained at near vacuum. Usually the plasma jets deviate from chemical and thermal equilibrium and the continuum approach is insufficient to describe the phenomena. In the current work, the continuum approach based Navier-Stokes equations have been implemented to study and understand the jet expansion process in a typical dual-arc plasma deposition reactor. The numerical predictions have been compared against in-house experimental data obtained by thermocouple measurements. For the range of back pressures (6-200 Pa) considered, it was observed that the jet core is supersonic and transitions to a subsonic zone downstream without the formation of any Mach disc for the prevalent operating parameters. Indications of thick and smeared barrel shocks were however observed in the computed flow-thermal fields. The modelled fluid was assumed to be a perfect gas with temperature dependent specific heats, thermal conductivity and viscosity coefficients, with constant Prandtl number of order unity. The radial spreads of the jets increase with increasing pressure ratio thus leading to enhanced interactions within reduced distances downstream of the nozzle exit. The jet core Mach number also increases, but moderately, with decreasing backpressure. It is concluded that within reasonable accuracy, continuum approach based calculations are able to capture most of the important phenomena involved in compressible, high-temperature, supersonic jet expansion processes which are essential in designing chambers relevant to the mentioned processes.

  2. DUHOCAMIS: a dual hollow cathode ion source for metal ion beams.

    PubMed

    Zhao, W J; Müller, M W O; Janik, J; Liu, K X; Ren, X T

    2008-02-01

    In this paper we describe a novel ion source named DUHOCAMIS for multiply charged metal ion beams. This ion source is derived from the hot cathode Penning ion gauge ion source (JINR, Dubna, 1957). A notable characteristic is the modified Penning geometry in the form of a hollow sputter electrode, coaxially positioned in a compact bottle-magnetic field along the central magnetic line of force. The interaction of the discharge geometry with the inhomogeneous but symmetrical magnetic field enables this device to be operated as hollow cathode discharge and Penning discharge as well. The main features of the ion source are the very high metal ion efficiency (up to 25%), good operational reproducibility, flexible and efficient operations for low charged as well as highly charged ions, compact setup, and easy maintenance. For light ions, e.g., up to titanium, well-collimated beams in the range of several tens of milliamperes of pulsed ion current (1 ms, 10/s) have been reliably performed in long time runs.

  3. Active induction balance method for metal detector sensing head utilizing transmitter-bucking and dual current source

    NASA Astrophysics Data System (ADS)

    Ambruš, D.; Vasić, D.; Bilas, V.

    2013-06-01

    A central problem in a design of frequency domain electromagnetic induction sensors used in landmine detection is an effective suppression of a direct inductive coupling between the transmitter and the receiver coil (induction balance, IB). In sensing heads based on the transmitter-bucking configuration, IB is achieved by using two concentric transmitter coils with opposing exciter fields in order to create a central magnetic cavity for the receiver coil. This design has numerous advantages over other IB methods in terms of detection sensitivity, spatial resolution, sensor dimensions and suitability for model-based measurements. However, very careful design and precise sensing head geometry are required if a single excitation source is used for driving both transmitter coils. In this paper we analyze the IB sensitivity to small perturbations of geometrical properties of coils. We propose a sensor design with dual current source and active induction balance scheme which overcomes the limitations of geometry-based balancing and potentially provides more efficient compensation of soil effects.

  4. Food sources of macro-invertebrates in an important mangrove ecosystem of Vietnam determined by dual stable isotope signatures

    NASA Astrophysics Data System (ADS)

    Tue, Nguyen Tai; Hamaoka, Hideki; Sogabe, Atsushi; Quy, Tran Dang; Nhuan, Mai Trong; Omori, Koji

    2012-08-01

    Dual stable isotope signatures (δ13C and δ15N) were applied to determine the contribution of mangrove materials and other organic carbon sources to the invertebrate community in an ecologically important mangrove ecosystem of Vietnam. We have analyzed 181 specimens of 30 invertebrate species and found δ13C and δ15N ranging from - 14.5 to - 26.8‰ and from 1.3 to 12.1‰, respectively. From taxa measured for stable isotopes, polychaete, gastropods, bivalves, and grapsid crabs living in mangrove forest showed relative low δ13C values, while fiddler crabs inhabiting in the land-water ecotone showed the highest δ13C values. The δ13C showed that just a few mangrove inhabitants directly relied on the mangrove materials. The wide ranges of δ13C and δ15N signatures indicated that the invertebrates utilized heterogeneous diets, comprising benthic microalgae, marine phytoplankton, particulate organic matter, sediment organic matter, mangrove detritus, and meiofauna and rotten animal tissues as the supplemental nutrient food sources. Moreover, the significant correlation between δ13C values and body sizes of invertebrates showed that snails Littoraria melanostoma and Terebralia sulcata, bivalve Glauconome virens, and portunid crab Scylla serrata exhibited ontogenetic shifts in diets. The present study showed that adjacent habitats such as tidal flat and mangrove creeks seem to contribute an important microalgal food resource for invertebrates and highlighted the need for conservations of mangrove forests and the adjacent habitats.

  5. Dual source CT (DSCT) imaging of obese patients: evaluation of CT number accuracy, uniformity, and noise

    NASA Astrophysics Data System (ADS)

    Walz-Flannigan, A.; Schmidt, B.,; Apel, A.; Eusemann, C.; Yu, L.; McCollough, C. H.

    2009-02-01

    Obese patients present challenges in obtaining sufficient x-ray exposure over reasonable time periods for acceptable CT image quality. To overcome this limitation, the exposure can be divided between two x-ray sources using a dualsource (DS) CT system. However, cross-scatter issues in DS CT may also compromise image quality. We evaluated a DS CT system optimized for imaging obese patients, comparing the CT number accuracy and uniformity to the same images obtained with a single-source (SS) acquisition. The imaging modes were compared using both solid cylindrical PMMA phantoms and a semi-anthropomorphic thorax phantom fitted with extension rings to simulate different size patients. Clinical protocols were used and CTDIvol and kVp were held constant between SS and DS modes. Results demonstrated good agreement in CT number between SS and DS modes in CT number, with the DS mode showing better axial uniformity for the largest phantoms.

  6. Evaluation of Wall Boundary Conditions for Impedance Eduction Using a Dual-Source Method

    NASA Technical Reports Server (NTRS)

    Watson, W. R.; Jones, M. G.

    2012-01-01

    The accuracy of the Ingard-Myers boundary condition and a recently proposed modified Ingard-Myers boundary condition is evaluated for use in impedance eduction under the assumption of uniform mean flow. The evaluation is performed at three centerline Mach numbers, using data acquired in a grazing flow impedance tube, using both upstream and downstream propagating sound sources, and on a database of test liners for which the expected behavior of the impedance spectra is known. The test liners are a hard-wall insert consisting of 12.6 mm thick aluminum, a linear liner without a facesheet consisting of a number of small diameter but long cylindrical channels embedded in a ceramic material, and two conventional nonlinear liners consisting of a perforated facesheet bonded to a honeycomb core. The study is restricted to a frequency range for which only plane waves are cut on in the hard-wall sections of the flow impedance tube. The metrics used to evaluate each boundary condition are 1) how well it educes the same impedance for upstream and downstream propagating sources, and 2) how well it predicts the expected behavior of the impedance spectra over the Mach number range. The primary conclusions of the study are that the same impedance is educed for upstream and downstream propagating sources except at the highest Mach number, that an effective impedance based on both the upstream and downstream measurements is more accurate than an impedance based on the upstream or downstream data alone, and that the Ingard-Myers boundary condition with an effective impedance produces results similar to that achieved with the modified Ingard-Myers boundary condition.

  7. Broadly tunable dual-wavelength light source for coherent anti-Stokes Raman scattering microscopy.

    PubMed

    Ganikhanov, Feruz; Carrasco, Silvia; Sunney Xie, X; Katz, Mordechai; Seitz, Wolfgang; Kopf, Daniel

    2006-05-01

    The signal and idler beams from a picosecond, synchronously pumped optical parametric oscillator (OPO) provide the two colors necessary for coherent anti-Stokes Raman scattering (CARS) microscopy. The OPO provides a continuously tunable frequency difference between the two beams over a broad range of Raman shifts (100-3700 cm(-1)) by varying the temperature of a single nonlinear crystal. The near-infrared output (900-1300 nm) allows for deep penetration into thick samples and reduced nonlinear photodamage. Applications of this light source to in vivo cell and ex vivo tissue imaging are demonstrated.

  8. Using dual isotopes to evaluate sources and transformations of nitrate in the West Lake watershed, eastern China

    NASA Astrophysics Data System (ADS)

    Jin, Zanfang; Qin, Xue; Chen, Lingxiao; Jin, Mantong; Li, Feili

    2015-06-01

    The West Lake is a World Heritage site in the West Lake watershed in eastern China. In this study, the hydrogeological and dual isotopic approaches were integrated to evaluate the seasonal and spatial variations of nitrate (NO3-) in the West Lake watershed, and to characterize NO3- sources and transformations. The results revealed that the geochemical facies of the water samples were dominated by Ca2 + + Na+-HCO3- + SO42- in the surface water and transfer water, Ca2 + + Na+-HCO3- and Ca2 + + Na+-SO42 - in the groundwater, which most likely reflect natural reactions and anthropogenic inputs. About 13% of the groundwater samples containing NO3- exceeded the World Health Organization (WHO) standard of 10 mg N L- 1. NO3- was the dominant form of total nitrogen (TN) and was the main surface water contaminant in the West Lake watershed. The δ15NNO3 and δ18ONO3 values indicated that the dominant NO3- sources in surface water were soil nitrogen (soil N) and chemical fertilizers, while the main NO3- sources in groundwater were soil N from the forest, chemical fertilizers and manure in the tea garden, domestic sewage from the small, old residential area in the forest as well as urban areas. The distribution of NO3- in groundwater was strongly influenced by land use. Results also suggest that there was significant nitrification in surface water and groundwater in the West Lake watershed, and that there were also denitrification processes in groundwater. The annual net fluxes of TN, NO3-, and NH4+ into the West Lake were 2.0 × 104, 4.0 × 103, and 1.31 × 104 kg as N, respectively.

  9. Image Quality and Radiation Dose for Prospectively Triggered Coronary CT Angiography: 128-Slice Single-Source CT versus First-Generation 64-Slice Dual-Source CT

    NASA Astrophysics Data System (ADS)

    Gu, Jin; Shi, He-Shui; Han, Ping; Yu, Jie; Ma, Gui-Na; Wu, Sheng

    2016-10-01

    This study sought to compare the image quality and radiation dose of coronary computed tomography angiography (CCTA) from prospectively triggered 128-slice CT (128-MSCT) versus dual-source 64-slice CT (DSCT). The study was approved by the Medical Ethics Committee at Tongji Medical College of Huazhong University of Science and Technology. Eighty consecutive patients with stable heart rates lower than 70 bpm were enrolled. Forty patients were scanned with 128-MSCT, and the other 40 patients were scanned with DSCT. Two radiologists independently assessed the image quality in segments (diameter >1 mm) according to a three-point scale (1: excellent; 2: moderate; 3: insufficient). The CCTA radiation dose was calculated. Eighty patients with 526 segments in the 128-MSCT group and 544 segments in the DSCT group were evaluated. The image quality 1, 2 and 3 scores were 91.6%, 6.9% and 1.5%, respectively, for the 128-MSCT group and 97.6%, 1.7% and 0.7%, respectively, for the DSCT group, and there was a statistically significant inter-group difference (P ≤ 0.001). The effective doses were 3.0 mSv in the 128-MSCT group and 4.5 mSv in the DSCT group (P ≤ 0.001). Compared with DSCT, CCTA with prospectively triggered 128-MSCT had adequate image quality and a 33.3% lower radiation dose.

  10. Detection of Special Nuclear Material from Delayed Neutron Emission Induced by a Dual-Particle Monoenergetic Source

    SciTech Connect

    Mayer, Michael F.; Nattress, J.; Jovanovic, I

    2016-06-30

    Detection of unique signatures of special nuclear materials is critical for their interdiction in a variety of nuclear security and nonproliferation scenarios. We report on the observation of delayed neutrons from fission of uranium induced in dual-particle active interrogation based on the 11B(d,n gamma)12C nuclear reaction. Majority of the fissions are attributed to fast fission induced by the incident quasi-monoenergetic neutrons. A Li-doped glass–polymer composite scintillation neutron detector, which displays excellent neutron/γ discrimination at low energies, was used in the measurements, along with a recoil-based liquid scintillation detector. Time- dependent buildup and decay of delayed neutron emission from 238U were measured between the interrogating beam pulses and after the interrogating beam was turned off, respectively. Characteristic buildup and decay time profiles were compared to the common parametrization into six delayed neutron groups, finding a good agreement between the measurement and nuclear data. This method is promising for detecting fissile and fissionable materials in cargo scanning applications and can be readily integrated with transmission radiography using low-energy nuclear reaction sources.

  11. Tetralogy of Fallot Cardiac Function Evaluation and Intelligent Diagnosis Based on Dual-Source Computed Tomography Cardiac Images.

    PubMed

    Cai, Ken; Rongqian, Yang; Li, Lihua; Xie, Zi; Ou, Shanxing; Chen, Yuke; Dou, Jianhong

    2016-05-01

    Tetralogy of Fallot (TOF) is the most common complex congenital heart disease (CHD) of the cyanotic type. Studies on ventricular functions have received an increasing amount of attention as the development of diagnosis and treatment technology for CHD continues to advance. Reasonable options for imaging examination and accurate assessment of preoperative and postoperative left ventricular functions of TOF patients are important in improving the cure rate of TOF radical operation, therapeutic evaluation, and judgment prognosis. Therefore, with the aid of dual-source computed tomography (DSCT), cardiac images with high temporal resolution and high definition, we measured the left ventricular time-volume curve using image data and calculating the left ventricular function parameters to conduct the preliminary evaluation on TOF patients. To comprehensively evaluate the cardiac function, the segmental ventricular wall function parameters were measured, and the measurement results were mapped to a bull's eye diagram to realize the standardization of segmental ventricular wall function evaluation. Finally, we introduced a new clustering method based on auto-regression model parameters and combined this method with Euclidean distance measurements to establish an intelligent diagnosis of TOF. The results of this experiment show that the TOF evaluation and the intelligent diagnostic methods proposed in this article are feasible.

  12. Influence of energy density of different light sources on Knoop hardness of a dual-cured resin cement.

    PubMed

    Piva, Evandro; Correr-Sobrinho, Lourenço; Sinhoreti, Mario Alexandre Coelho; Consani, Simonides; Demarco, Flávio Fernando; Powers, John Michael

    2008-01-01

    The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs) were tested: tungsten halogen light (HAL), light-emitting diode (LED) and xenon plasma-arc (PAC) lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce). Three energy doses were used by modifying the irradiance (I) of each LCU and the irradiation time (T): 24 Jcm(-2) (I/2x2T), 24 Jcm(-2) (IxT) and 48 Jcm(-2) (Ix2T). Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus). Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10). Knoop hardness number (KHN) means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (alpha=5%). Application of 48 J.cm(-2) energy dose through the ceramic using LED (50.5+/-2.8) and HAL (50.9+/-3.7) produced significantly higher KHN means (p<0.05) than the control (44.7+/-3.8). LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase.

  13. Detection of special nuclear material from delayed neutron emission induced by a dual-particle monoenergetic source

    NASA Astrophysics Data System (ADS)

    Mayer, M.; Nattress, J.; Jovanovic, I.

    2016-06-01

    Detection of unique signatures of special nuclear materials is critical for their interdiction in a variety of nuclear security and nonproliferation scenarios. We report on the observation of delayed neutrons from fission of uranium induced in dual-particle active interrogation based on the 11B(d,n γ)12C nuclear reaction. Majority of the fissions are attributed to fast fission induced by the incident quasi-monoenergetic neutrons. A Li-doped glass-polymer composite scintillation neutron detector, which displays excellent neutron/γ discrimination at low energies, was used in the measurements, along with a recoil-based liquid scintillation detector. Time-dependent buildup and decay of delayed neutron emission from 238U were measured between the interrogating beam pulses and after the interrogating beam was turned off, respectively. Characteristic buildup and decay time profiles were compared to the common parametrization into six delayed neutron groups, finding a good agreement between the measurement and nuclear data. This method is promising for detecting fissile and fissionable materials in cargo scanning applications and can be readily integrated with transmission radiography using low-energy nuclear reaction sources.

  14. A dual-energy medical instrument for measurement of x-ray source voltage and dose rate

    NASA Astrophysics Data System (ADS)

    Ryzhikov, V. D.; Naydenov, S. V.; Volkov, V. G.; Opolonin, O. D.; Makhota, S.; Pochet, T.; Smith, C. F.

    2016-03-01

    An original dual-energy detector and medical instrument have been developed to measure the output voltages and dose rates of X-ray sources. Theoretical and experimental studies were carried out to characterize the parameters of a new scintillator-photodiode sandwich-detector based on specially-prepared zinc selenide crystals in which the low-energy detector (LED) works both as the detector of the low-energy radiation and as an absorption filter allowing the highenergy fraction of the radiation to pass through to the high-energy detector (HED). The use of the LED as a low-energy filter in combination with a separate HED opens broad possibilities for such sandwich structures. In particular, it becomes possible to analyze and process the sum, difference and ratio of signals coming from these detectors, ensuring a broad (up to 106) measurement range of X-ray intensity from the source and a leveling of the energy dependence. We have chosen an optimum design of the detector and the geometry of the component LED and HED parts that allow energy-dependence leveling to within specified limits. The deviation in energy dependence of the detector does not exceed about 5% in the energy range from 30 to 120 keV. The developed detector and instrument allow contactless measurement of the anode voltage of an X-ray emitter from 40 to 140 kV with an error no greater than 3%. The dose rate measurement range is from 1 to 200 R/min. An original medical instrument has passed clinical testing and was recommended for use in medical institutions for X-ray diagnostics.

  15. Ultra-high-resolution dual-source CT for forensic dental visualization-discrimination of ceramic and composite fillings.

    PubMed

    Jackowski, C; Wyss, M; Persson, A; Classens, M; Thali, M J; Lussi, A

    2008-07-01

    Dental identification is the most valuable method to identify human remains in single cases with major postmortem alterations as well as in mass casualties because of its practicability and demanding reliability. Computed tomography (CT) has been investigated as a supportive tool for forensic identification and has proven to be valuable. It can also scan the dentition of a deceased within minutes. In the present study, we investigated currently used restorative materials using ultra-high-resolution dual-source CT and the extended CT scale for the purpose of a color-encoded, in scale, and artifact-free visualization in 3D volume rendering. In 122 human molars, 220 cavities with 2-, 3-, 4- and 5-mm diameter were prepared. With presently used filling materials (different composites, temporary filling materials, ceramic, and liner), these cavities were restored in six teeth for each material and cavity size (exception amalgam n = 1). The teeth were CT scanned and images reconstructed using an extended CT scale. Filling materials were analyzed in terms of resulting Hounsfield units (HU) and filling size representation within the images. Varying restorative materials showed distinctively differing radiopacities allowing for CT-data-based discrimination. Particularly, ceramic and composite fillings could be differentiated. The HU values were used to generate an updated volume-rendering preset for postmortem extended CT scale data of the dentition to easily visualize the position of restorations, the shape (in scale), and the material used which is color encoded in 3D. The results provide the scientific background for the application of 3D volume rendering to visualize the human dentition for forensic identification purposes.

  16. The superior aspect of the perirenal space: could it be depicted by dual-source CT in vivo in adults

    PubMed Central

    Qi, R; Zhou, X P; Li, Z L

    2015-01-01

    Objective: This study aims to observe whether the renal fascias could be effectively shown by dual-source CT (DSCT) and to explore the superior communication of the perirenal space (PS) in vivo in adults. Methods: 275 cases were included in the normal group and 124 cases in the acute pancreatitis group in this study; all images obtained by DSCT were observed; the superior adherence of the renal fascias and the pattern of superior communication of the PS were judged; and the consistency between the two groups was compared. Results: The superior adherence of the renal fascias was reliably displayed in 57.8% of the normal group and 69.4% of the acute pancreatitis group, the anterior renal fascia (ARF) did not fuse with the posterior renal fascia superiorly. The left ARF fused with the posterior parietal peritoneum in 57.9% of the normal group and 45.3% of the pancreatitis group, where the left PS communicated with the subdiaphragmatic retroperitoneal space (SDRS). The left ARF fused with the peritoneum laterally and simultaneously with the inferior phrenic fascia medially in 42.1% and 54.7% of each group, respectively, where the left PS was open towards the SDRS laterally but sealed off from the SDRS medially. The right ARF fused with the peritoneum in all cases; and the right PS was open towards the bare area of the liver. Conclusion: To some extent, DSCT can display renal fascia and its superior adherence and reflect the superior communication of the PS. Advances in knowledge: This study was conducted in vivo in adults by high-resolution DSCT, and more samples could be provided. PMID:25411900

  17. Performance of dual-source CT with high pitch spiral mode for coronary stent patency compared with invasive coronary angiography

    PubMed Central

    Yang, Xia; Yu, Qiang; Dong, Wei; Fu, Zhen-Hong; Yang, Jun-Jue; Guo, Jun; Chen, Yun-Dai

    2016-01-01

    Objective To investigate the performance of dual-source computed tomography (DSCT) using high-pitch spiral (HPS) mode for coronary stents patency. Methods We conducted a prospective study on 120 patients with 260 previous stents implanted due to recurred suspicious symptoms of angina scheduled for invasive coronary angiography (ICA), while DSCT were conducted using HPS mode. Results There was no significant impact of age, body mass index or heat rate (HR) on image quality (P > 0.05), while HR variability had a slight impact on that (P < 0.05). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) of DSCT in detection of in-stent restenosis (ISR) based per-patient were 92.3%, 96.7%, 88.9%, and 97.8%, respectively. And those based per-stent were 87%, 96.8%, 83.3%, and 97.7% with un-assessment stents, 97.4%, 99.5%, 97.4%, and 99.5% without un-assessment stents. There was significant difference on sensitivity, specificity, PPV and NPV between diameter ≥ 3.0 mm group (93.3%, 97.9%, 87.5%, and 98.9%) and diameter < 3.0 mm group (80%, 93.3%, 80.0%, and 93.3%) (P < 0.05), and that between stent number ≥ 3 group (82.3%, 77.8%, 66.7%, and 60%) with < 3 group (97.3%, 80%, 96.5%, and 75%). The effective dose of DSCT (1.4 ± 0.5 mSv) is significantly less than that by invasive coronary angiography [4.0 ± 0.8 mSv (P < 0.01)]. Conclusion DSCT using HPS mode provides good diagnostic performance on stent patency with lower effective dose in patients with HR < 65 beats/min. PMID:27928222

  18. Imaging of the Coronary Venous System: Validation of Three-Dimensional Rotational Venous Angiography Against Dual-Source Computed Tomography

    SciTech Connect

    Knackstedt, Christian; Muehlenbruch, Georg; Mischke, Karl; Bruners, Philipp; Schimpf, Thomas; Frechen, Dirk; Schummers, Georg; Mahnken, Andreas H.; Guenther, Rolf W.; Kelm, Malte; Schauerte, Patrick

    2008-11-15

    Information on the anatomy of the cardiac venous system (CVS) is increasingly important for cardiac resynchronization therapy or percutaneous transvenous mitral valve annuloplasty. Three-dimensional (3D) imaging can further improve the understanding of the relationship of cardiac structures. This study was performed to validate the accuracy of rotational coronary sinus angiography (CSA) displaying the 3D anatomy of the CVS compared to ECG-gated, contrast-enhanced, cardiac dual-source computed tomography (DSCT). Five domestic pigs (60 kg) underwent DSCT using a standardized examination protocol. Using a standard C-arm for fluoroscopy, a rotational CSA was obtained and 3D-image reconstructions performed. Side branches were identified using both methods and enumerated. Vessel visibility was estimated for each side branch and great cardiac vein/anterior interventricular vein. Also, vessel diameters were measured at distinct landmarks, i.e., side branching. The amount of contrast medium was determined and the effective radiation exposure of both methods was calculated. There was no significant difference regarding the vessel diameter of the great cardiac vein/anterior interventricular vein or its side branches. Also, estimation of vessel visibility was not different between the two imaging modalities. Estimated radiation exposure and amount of contrast medium were lower for rotational CSA. In conclusion, a 3D reconstruction of rotational CSA images is possible. All parts of the CVS are well depicted, allowing a 3D overview of the CVS anatomy. On-site 3D visualization might improve decision making during cardiac interventions. In contrast to DSCT, rotational CSA does not demonstrate the anatomy of the mitral annulus or the course of the left circumflex artery.

  19. Compact High-Repetition-Rate Monochromatic Terahertz Source Based on Difference Frequency Generation from a Dual-Wavelength Nd:YAG Laser and DAST Crystal

    NASA Astrophysics Data System (ADS)

    Zhong, Kai; Mei, Jialin; Wang, Maorong; Liu, Pengxiang; Xu, Degang; Wang, Yuye; Shi, Wei; Yao, Jianquan; Teng, Bing; Xiao, Yong

    2017-01-01

    Although high-repetition-rate dual-wavelength Nd:YAG lasers at 1319 and 1338 nm have been realized for quite a long time, we have employed it in generating monochromatic terahertz (THz) wave in this paper for the first time. The dual-wavelength laser was LD-end-pumped and acousto-optically (AO) Q-switched with the output power of watt level operating at different repetition rates from 5.5 to 30 kHz. Using a 0.6-mm-thick organic nonlinear crystal DAST for difference frequency generation (DFG), a compact terahertz source was achieved at 3.28 THz. The maximum average output power was about 0.58 μW obtained at a repetition rate of 5.5 kHz, corresponding to the conversion efficiency of about 6.4 × 10-7. The output power scaling is still feasible with higher pump power and a longer nonlinear DFG crystal. Owing to the compactness of the dual-wavelength laser and the nonlinear crystal, a palm-top terahertz source is expected for portable applications such as imaging and so on.

  20. Plasma characteristics of single- and dual-electrode ion source systems utilized in low-energy ion extraction

    SciTech Connect

    Vasquez, M. R.; Tokumura, S.; Kasuya, T.; Wada, M.

    2014-02-15

    Discharge characteristics in the upstream as well as in the downstream regions of a 50-eV positive ion beam were measured along the beam axis. Single- and dual-electrode configurations made of 0.1-mm diameter tungsten wires were tested. By varying the upstream discharge parameters, the shape of the sheath edge around the extractors, which can either be “planar” or “cylindrical,” can be controlled. The sheath eventually affected the simultaneous extraction of ions and neutralizing electrons. The dual-electrode configuration at the lower discharge current, revealed a homogeneous discharge downstream. At this condition, the edge of the sheath can be inferred to be “planar” which allowed the uniform extraction and propagation of low-energy ions at longer distances. The dual-electrode configuration was capable of transmitting low-energy ions up to 70 mm downstream.

  1. Contrast material injection protocol with the flow rate adjusted to the heart rate for dual source CT coronary angiography.

    PubMed

    Zhu, Xiaomei; Chen, Wenping; Li, Mei; Xu, Yi; Xu, Hai; Zhu, Yinsu; Wang, Dehang; Tang, Lijun

    2012-08-01

    To investigate the effect on coronary arterial attenuations of contrast material flow rate adjusted to a patient's heart rate during dual source CT coronary angiography (DSCT-CCTA). A total of 296 consecutive patients (mean age: 58.7 years) undergoing DSCT-CCTA without previous coronary stent placement, bypass surgery, congenital or valvular heart disease were included. The image acquisition protocol was standardized (120 kV, 380 mAs) and retrospective electrocardiograph (ECG) gating was used. Patients were randomly assigned to one of three groups [flow rate: G1: dosage/16, G2: dosage/(scan time +8), G3: fixed flow rate]. The groups were compared with respect to the attenuations of the ascending aorta (AA) above coronary ostia, the left main coronary artery (LM), the proximal right coronary artery (RCA), the left anterior descending artery (LAD), the left circumflex artery (LCX), and the contrast to noise ratio of the LM (LM(CNR)) and the proximal RCA (RCA(CNR)). Correlations between heart rate and attenuation of the coronary arteries were evaluated in three groups with linear regression. There was no significant difference in the three groups among the mean attenuations of AA (P = 0.141), LM (P = 0.068), RCA (P = 0.284), LM(CNR) (P = 0.598) and RCA(CNR) (P = 0.546). The attenuations of the LAD and the LCX in group 1 were slightly higher than those in group 2 and 3 (P < 0.05). In group 1, the attenuations of the AA (P < 0.01), LM (P < 0.01), RCA (P < 0.01), LAD (P = 0.02) and LCX (P < 0.01) decreased, respectively, with an increasing heart rate. A similar finding was detected in group 3 (AA: P < 0.01, LM: P < 0.01, RCA: P < 0.01, LAD: P < 0.01 and LCX: P < 0.01). In contrast, the attenuations of the AA (P = 0.55), LM (P = 0.27), RCA (P = 0.77), LAD (P = 0.22) and LCX (P = 0.74) had no significant correlation with heart rate in group 2. In all three groups, LM(CNR) (P = 0.77, 0.69 and 0.73 respectively) and RCA(CNR) (P = 0.75, 0.39 and 0.61 respectively) had no

  2. Identification of benign and malignant thyroid nodules by in vivo iodine concentration measurement using single-source dual energy CT

    PubMed Central

    Gao, Shun-Yu; Zhang, Xiao-Yan; Wei, Wei; Li, Xiao-Ting; Li, Yan-Ling; Xu, Min; Sun, Ying-Shi; Zhang, Xiao-Peng

    2016-01-01

    Abstract This study proposed to determine whether in vivo iodine concentration measurement by single-source dual energy (SSDE) CT can improve differentiation between benign and malignant thyroid nodules. In total, 53 patients presenting with thyroid nodules underwent SSDE CT scanning. Iodine concentrations were measured for each nodule and normal thyroid tissue using the GSI-viewer image analysis software. A total of 26 thyroid nodules were malignant in 26 patients and confirmed by surgery; 33 nodules from 27 patients were benign, with 10 confirmed by surgery and others after follow-up. Iodine concentrations with plain CT were significantly lower in malignant than benign nodules (0.47 ± 0.20 vs 1.17 ± 0.38 mg/mL, P = 0.00). Receiver operating characteristic (ROC) curve showed an area under the curve (AUC) of 0.93; with a cutoff of 0.67, iodine concentration showed 92.3% sensitivity and 88.5% specificity in diagnosing malignancy. Iodine concentration obtained by enhanced and plain CT were significantly higher in malignant than benign nodules (9.05 ± 3.35 vs 3.46 ± 2.24 mg/mL, P = 0.00). ROC curve analysis showed an AUC of 0.93; with a cutoff value of 3.37, iodine concentration displayed 78% sensitivity, 95% specificity in diagnosing malignancy. Combining unenhanced with enhanced iodine concentrations, the diagnostic equation was: Y = –8.641 × unenhanced iodine concentration + 0.663 × iodine concentration. ROC curve showed an AUC of 0.98 (95% CI, 0.94, 1.00). With Y ≥ –2 considered malignancy, diagnostic sensitivity and specificity were 96%, 96.3%, respectively. This study concluded that SSDE CT can detect the differences in iodine uptake and blood supply between benign and malignant thyroid lesions. PMID:27684811

  3. Neural correlates of confidence during item recognition and source memory retrieval: evidence for both dual-process and strength memory theories.

    PubMed

    Hayes, Scott M; Buchler, Norbou; Stokes, Jared; Kragel, James; Cabeza, Roberto

    2011-12-01

    Although the medial-temporal lobes (MTL), PFC, and parietal cortex are considered primary nodes in the episodic memory network, there is much debate regarding the contributions of MTL, PFC, and parietal subregions to recollection versus familiarity (dual-process theory) and the feasibility of accounts on the basis of a single memory strength process (strength theory). To investigate these issues, the current fMRI study measured activity during retrieval of memories that differed quantitatively in terms of strength (high vs. low-confidence trials) and qualitatively in terms of recollection versus familiarity (source vs. item memory tasks). Support for each theory varied depending on which node of the episodic memory network was considered. Results from MTL best fit a dual-process account, as a dissociation was found between a right hippocampal region showing high-confidence activity during the source memory task and bilateral rhinal regions showing high-confidence activity during the item memory task. Within PFC, several left-lateralized regions showed greater activity for source than item memory, consistent with recollective orienting, whereas a right-lateralized ventrolateral area showed low-confidence activity in both tasks, consistent with monitoring processes. Parietal findings were generally consistent with strength theory, with dorsal areas showing low-confidence activity and ventral areas showing high-confidence activity in both tasks. This dissociation fits with an attentional account of parietal functions during episodic retrieval. The results suggest that both dual-process and strength theories are partly correct, highlighting the need for an integrated model that links to more general cognitive theories to account for observed neural activity during episodic memory retrieval.

  4. Value of Virtual Colonoscopy with 64 Row CT in Evaluation of Colorectal Cancer

    PubMed Central

    Zaleska-Dorobisz, Urszula; Łasecki, Mateusz; Nienartowicz, Ewa; Pelak, Joanna; Słonina, Joanna; Olchowy, Cyprian; Ścieżka, Marek; Sąsiadek, Marek

    2014-01-01

    Summary Background Virtual colonoscopy (VC) enables three-dimensional view of walls and internal lumen of the colon as a result of reconstruction of multislice CT images. The role of VC in diagnosis of the colon abnormalities systematically increases, and in many medical centers all over the world is carried out as a screening test of patients with high risk of colorectal cancer. Material/Methods We analyzed results of virtual colonoscopy of 360 patients with clinical suspicion of colorectal cancer. Sensitivity and specificity of CT colonoscopy for detection of colon cancers and polyps were assessed. Results Results of our research have shown high diagnostic efficiency of CT colonoscopy in detection of focal lesions in large intestine of 10 mm or more diameter. Sensitivity was 85.7%, specificity 89.2%. Conclusions Virtual colonoscopy is noninvasive and well tolerated by patients imaging method, which permits for early detection of the large intestine lesions with specificity and sensitivity similar to classical colonoscopy in screening exams in patients suspected for colorectal cancer. Good preparation of the patients for the examination is very important for proper diagnosis and interpretation of this imaginge procedure. PMID:25302086

  5. Screening for coronary artery disease in respiratory patients: comparison of single- and dual-source CT in patients with a heart rate above 70 bpm.

    PubMed

    Pansini, Vittorio; Remy-Jardin, Martine; Tacelli, Nunzia; Faivre, Jean-Baptiste; Flohr, Thomas; Deken, Valérie; Duhamel, Alain; Remy, Jacques

    2008-10-01

    To evaluate the assessibility of coronary arteries in respiratory patients with high heart rates. This study was based on the comparative analysis of two paired populations of 54 patients with a heart rate >70 bpm evaluated with dual-source (group 1) and single-source (group 2) CT. The mean heart rate was 89.1 bpm in group 1 and 86.7 bpm in group 2 (P=0.26). The mean number of assessable segments per patient was significantly higher in group 1 compared to group 2 (P dual-source CT suggests that high heart rates should no longer be considered as contraindications for ECG-gated CT angiograms of the chest whenever clinically relevant.

  6. Cardiac MOLLI T1 mapping at 3.0 T: comparison of patient-adaptive dual-source RF and conventional RF transmission.

    PubMed

    Rasper, Michael; Nadjiri, Jonathan; Sträter, Alexandra S; Settles, Marcus; Laugwitz, Karl-Ludwig; Rummeny, Ernst J; Huber, Armin M

    2017-01-30

    To prospectively compare image quality and myocardial T1 relaxation times of modified Look-Locker inversion recovery (MOLLI) imaging at 3.0 T (T) acquired with patient-adaptive dual-source (DS) and conventional single-source (SS) radiofrequency (RF) transmission. Pre- and post-contrast MOLLI T1 mapping using SS and DS was acquired in 27 patients. Patient wise and segment wise analysis of T1 times was performed. The correlation of DS MOLLI measurements with a reference spin echo sequence was analysed in phantom experiments. DS MOLLI imaging reduced T1 standard deviation in 14 out of 16 myocardial segments (87.5%). Significant reduction of T1 variance could be obtained in 7 segments (43.8%). DS significantly reduced myocardial T1 variance in 16 out of 25 patients (64.0%). With conventional RF transmission, dielectric shading artefacts occurred in six patients causing diagnostic uncertainty. No according artefacts were found on DS images. DS image findings were in accordance with conventional T1 mapping and late gadolinium enhancement (LGE) imaging. Phantom experiments demonstrated good correlation of myocardial T1 time between DS MOLLI and spin echo imaging. Dual-source RF transmission enhances myocardial T1 homogeneity in MOLLI imaging at 3.0 T. The reduction of signal inhomogeneities and artefacts due to dielectric shading is likely to enhance diagnostic confidence.

  7. A dual-plane co-RASOR technique for accurate and rapid tracking and position verification of an Ir-192 source for single fraction HDR brachytherapy

    NASA Astrophysics Data System (ADS)

    de Leeuw, Hendrik; Moerland, Marinus A.; van Vulpen, Marco; Seevinck, Peter R.; Bakker, Chris J. G.

    2013-11-01

    Effective high-dose-rate (HDR) treatment requires accurate and independent treatment verification to ensure that the treatment proceeds as prescribed, in particular if a high dose is given, as in single fraction therapy. Contrary to CT imaging and fluoroscopy, MR imaging provides high soft tissue contrast. Conventional MR techniques, however, do not offer the temporal resolution in combination with the 3D spatial resolution required for accurate brachytherapy source localization. We have developed an MR imaging method (center-out RAdial Sampling with Off-Resonance (co-RASOR)) that generates high positive contrast in the geometrical center of field perturbing objects, such as HDR brachytherapy sources. co-RASOR generates high positive contrast in the geometric center of an Ir-192 source by applying a frequency offset to center-out encoded data. To obtain high spatial accuracy in 3D with adequate temporal resolution, two orthogonal center-out encoded 2D images are applied instead of a full 3D acquisition. Its accuracy in 3D is demonstrated by 3D MRI and CT. The 2D images show high positive contrast in the geometric center of non-radioactive Ir-192 sources, with signal intensities up to 160% of the average signal intensity in the surrounding medium. The accuracy with which the center of the Ir-192 source is located by the dual-plane MRI acquisition corresponds closely to the accuracy obtained by 3D MRI and CT imaging. The positive contrast is shown to be obtained in homogeneous and in heterogeneous tissue. The dual-plane MRI technique allows the brachytherapy source to be tracked in 3D with millimeter accuracy with a temporal resolution of approximately 4 s.

  8. An Aneurysmal Left Circumflex Artery-to-Right Atrium Fistula in a Patient with Ischemic Symptoms: Accurate Diagnosis with Dual-Source CT Angiography

    SciTech Connect

    Oncel, Dilek Oncel, Guray

    2008-07-15

    In this report, we present a 55-year-old female patient with a left circumflex artery-to-right atrial fistula associated with a huge saccular aneurysm. She had undergone conventional angiography due to ischemic symptoms. In conventional angiography, a very dilated and tortuous vessel originating from the circumflex artery and continuous with a huge saccular aneurysm was visualized but the drainage site could not be demonstrated. With dual-source CT coronary angiography, the exact anatomy of this fistula was demonstrated and surgery was planned.

  9. Microwave observation of H 3N-SO 3⋯H 2O using a concentric, dual-injection nozzle source

    NASA Astrophysics Data System (ADS)

    Hunt, S. W.; Brauer, C. S.; Craddock, M. B.; Higgins, K. J.; Nienow, A. M.; Leopold, K. R.

    2004-10-01

    The complex H 3N-SO 3⋯ H 2O is observed by pulsed nozzle Fourier transform microwave spectroscopy using a newly designed concentric, dual-injection nozzle source. This source allows two reactive species to be injected independently into a seeded supersonic expansion by introducing gases through a pair of concentric hypodermic needles situated downstream of the nozzle orifice. Microwave spectra of the parent form of H 3N-SO 3⋯H 2O, as well as nine isotopically substituted derivatives are observed, and the N-S bond length is estimated to be 1.83(13) Å. This value is in reasonable agreement with previous theoretical calculations and suggests that the complexation of H 3N-SO 3 with water produces a substantial contraction of the nitrogen-sulfur bond. The spectrum shows no evidence of internal motion of the water subunit.

  10. Accuracy of dual-source CT to identify significant coronary artery disease in patients with uncontrolled hypertension presenting with chest pain: comparison with coronary angiography.

    PubMed

    Marwan, Mohamed; Pflederer, Tobias; Schepis, Tiziano; Seltmann, Martin; Klinghammer, Lutz; Muschiol, Gerd; Ropers, Dieter; Daniel, Werner G; Achenbach, Stephan

    2012-06-01

    It has been previously reported that the sensitivity and specificity of multislice CT for detecting significant CAD (coronary artery disease) is high. Chest pain is a common presentation in patients with uncontrolled hypertension. We investigated the sensitivity and specificity of dual-source CT to detect and rule out significant CAD in patients presenting with uncontrolled hypertension accompanied by chest pain. 260 consecutive patients presenting with acute chest pain in the context of stage 2 hypertension (systolic pressure ≥160 and/or diastolic pressure ≥100) were enrolled in the study. After admission, control of blood pressure and risk stratification, 82 patients were excluded due to renal insufficiency, prior coronary revascularisation or refused participation in the study. 90 further patients with low pre-test probability of CAD were also excluded. 88 remaining patients were subjected to CT coronary angiography using dual-source CT (Definition, Siemens Medical Solutions, Forchheim, Germany) within 24 h before invasive coronary angiography. A contrast-enhanced volume dataset was acquired (120 kV, 400 mAs/rot, collimation 2 × 64 × 0.6 mm, retrospective ECG gating). Data sets were evaluated concerning the presence or absence of significant coronary stenoses and validated against invasive coronary angiography. A significant stenosis was assumed if the diameter reduction was ≥50%. 88 patients (mean age 66 ± 11 years, mean heart rate 61 ± 9 bpm) were evaluated regarding the presence or absence of significant CAD (at least one stenosis ≥50% diameter reduction). Mean systolic blood pressure on presentation was 203 ± 20 mmHg and mean diastolic blood pressure was 103 ± 13 mmHg. On a per patient basis, the sensitivity and specificity for dual-source CT to detect significant CAD in vessels >1.5 mm diameter was 100% (36/36, 95% CI 90-100) and 90% (47/52, 95% CI 79-97), respectively with a negative predictive value (NPV) of 100% (47/47, 95% CI 92-100) and a

  11. SU-D-207-03: Development of 4D-CBCT Imaging System with Dual Source KV X-Ray Tubes

    SciTech Connect

    Nakamura, M; Ishihara, Y; Matsuo, Y; Ueki, N; Iizuka, Y; Mizowaki, T; Hiraoka, M

    2015-06-15

    Purpose: The purposes of this work are to develop 4D-CBCT imaging system with orthogonal dual source kV X-ray tubes, and to determine the imaging doses from 4D-CBCT scans. Methods: Dual source kV X-ray tubes were used for the 4D-CBCT imaging. The maximum CBCT field of view was 200 mm in diameter and 150 mm in length, and the imaging parameters were 110 kV, 160 mA and 5 ms. The rotational angle was 105°, the rotational speed of the gantry was 1.5°/s, the gantry rotation time was 70 s, and the image acquisition interval was 0.3°. The observed amplitude of infrared marker motion during respiration was used to sort each image into eight respiratory phase bins. The EGSnrc/BEAMnrc and EGSnrc/DOSXYZnrc packages were used to simulate kV X-ray dose distributions of 4D-CBCT imaging. The kV X-ray dose distributions were calculated for 9 lung cancer patients based on the planning CT images with dose calculation grid size of 2.5 x 2.5 x 2.5 mm. The dose covering a 2-cc volume of skin (D2cc), defined as the inner 5 mm of the skin surface with the exception of bone structure, was assessed. Results: A moving object was well identified on 4D-CBCT images in a phantom study. Given a gantry rotational angle of 105° and the configuration of kV X-ray imaging subsystems, both kV X-ray fields overlapped at a part of skin surface. The D2cc for the 4D-CBCT scans was in the range 73.8–105.4 mGy. Linear correlation coefficient between the 1000 minus averaged SSD during CBCT scanning and D2cc was −0.65 (with a slope of −0.17) for the 4D-CBCT scans. Conclusion: We have developed 4D-CBCT imaging system with dual source kV X-ray tubes. The total imaging dose with 4D-CBCT scans was up to 105.4 mGy.

  12. Dual-frequency comb generation with differing GHz repetition rates by parallel Fabry-Perot cavity filtering of a single broadband frequency comb source

    NASA Astrophysics Data System (ADS)

    Mildner, Jutta; Meiners-Hagen, Karl; Pollinger, Florian

    2016-07-01

    We present a dual-comb-generator based on a coupled Fabry-Perot filtering cavity doublet and a single seed laser source. By filtering a commercial erbium-doped fiber-based optical frequency comb with CEO-stabilisation and 250 MHz repetition rate, two broadband coherent combs of different repetition rates in the GHz range are generated. The filtering doublet consists of two Fabry-Perot cavities with a tunable spacing and Pound-Drever-Hall stabilisation scheme. As a prerequisite for the development of such a filtering unit, we present a method to determine the actual free spectral range and transmission bandwidth of a Fabry-Perot cavity in situ. The transmitted beat signal of two diode lasers is measured as a function of their tunable frequency difference. Finally, the filtering performance and resulting beat signals of the heterodyned combs are discussed as well as the optimisation measures of the whole system.

  13. Multiparametric Evaluation of Head and Neck Squamous Cell Carcinoma Using a Single-Source Dual-Energy CT with Fast kVp Switching: State of the Art.

    PubMed

    Lam, Stephanie; Gupta, Rajiv; Kelly, Hillary; Curtin, Hugh D; Forghani, Reza

    2015-11-06

    There is an increasing body of evidence establishing the advantages of dual-energy CT (DECT) for evaluation of head and neck squamous cell carcinoma (HNSCC). Focusing on a single-source DECT system with fast kVp switching, we will review the principles behind DECT and associated post-processing steps that make this technology especially suitable for HNSCC evaluation and staging. The article will review current applications of DECT for evaluation of HNSCC including use of different reconstructions to improve tumor conspicuity, tumor-normal soft tissue interface, accuracy of invasion of critical structures such as thyroid cartilage, and reduce dental artifact. We will provide a practical approach for DECT implementation into routine clinical use and a multi-parametric approach for scan interpretation based on the experience at our institution. The article will conclude with a brief overview of potential future applications of the technique.

  14. Power combination of two phase-locked high power microwave beams from a new coaxial microwave source based on dual beams

    SciTech Connect

    Li, Yangmei; Zhang, Xiaoping Zhang, Jiande; Dang, Fangchao; Yan, Xiaolu

    2014-10-15

    The new coaxial high power microwave source based on dual beams has demonstrated two phase-locked output microwave beams generated by its two sub-sources. In order to achieve a single higher output power, we present a three-port waveguide-based power combiner to combine the two microwave beams. Particle-in-cell simulation results show that when the diode voltage is 675 kV and the guiding magnetic field is 0.8 T, a combined microwave with an average power of about 4.0 GW and a frequency of 9.74 GHz is generated; the corresponding power conversion efficiency is 29%. The combination effect of the combiner is further validated in the diode voltage range from 675 kV to 755 kV as well as in the pulse regime. The simulations indicate that the maximum surface axial electric field strength of the electrodynamic structure is 720 kV/cm, which is relatively low corresponding to an output power of 4.0 GW. The stable combined output suggests the probability of long-pulse operation for the combined source.

  15. A Dual-Channel, Curved-Crystal Spectrograph for Petawatt Laser, X-Ray Backlighter Source Studies

    SciTech Connect

    Theobald, W.; Stoeckl, C.; Jaanimagi, P.A.; Nilson, P.M.; Storm, M.; Meyerhofer, D.D.; Sangster, T.C.; Hey, D.; MacKinnon, A.J.; Park, H.-S.; Patel, P.K.; Shepherd, R.; Snavely, R.A.; Key, M.H.; King, J.A.; Zhang, B.; Stephens, R.B.; Akli, K.U.; Highbarger, K.; Daskalova, R.L.; VanWoerkom, L.; Freeman, R.R.; Green, J.S.; Gregori, G.; Lancaster, K.; Norreys, P.A.

    2009-08-19

    A dual-channel, curved-crystal spectrograph was designed to measure time-integrated x-ray spectra in the ~1.5 to 2 keV range (6.2–8.2 Å wavelength) from small-mass, thin-foil targets irradiated by the VULCAN petawatt laser focused up to 4 x 10^20 W/cm^2. The spectrograph consists of two cylindrically curved potassium-acid-phthalate crystals bent in the meridional plane to increase the spectral range by a factor of ~10 compared to a flat crystal. The device acquires single-shot x-ray spectra with good signal-to-background ratios in the hard x-ray background environment of petawatt laser-plasma interactions. The peak spectral energies of the aluminum He-alpha and Ly-alpha resonance lines were ~1.8 and ~1.0 mJ/eV sr (~0.4 and 0.25 J/Å sr), respectively, for 220 J, 10 ps laser irradiation.

  16. A dual-channel, curved-crystal spectrograph for petawatt laser, x-ray backlighter source studies

    SciTech Connect

    Theobald, W.; Stoeckl, C.; Jaanimagi, P. A.; Nilson, P. M.; Storm, M.; Meyerhofer, D. D.; Sangster, T. C.; Hey, D.; MacKinnon, A. J.; Park, H.-S.; Patel, P. K.; Shepherd, R.; Snavely, R. A.; Key, M. H.; King, J. A.; Zhang, B.; Stephens, R. B.; Akli, K. U.; Highbarger, K.; Daskalova, R. L.; and others

    2009-08-15

    A dual-channel, curved-crystal spectrograph was designed to measure time-integrated x-ray spectra in the {approx}1.5 to 2 keV range (6.2-8.2 A wavelength) from small-mass, thin-foil targets irradiated by the VULCAN petawatt laser focused up to 4x10{sup 20} W/cm{sup 2}. The spectrograph consists of two cylindrically curved potassium-acid-phthalate crystals bent in the meridional plane to increase the spectral range by a factor of {approx}10 compared to a flat crystal. The device acquires single-shot x-ray spectra with good signal-to-background ratios in the hard x-ray background environment of petawatt laser-plasma interactions. The peak spectral energies of the aluminum He{sub {alpha}} and Ly{sub {alpha}} resonance lines were {approx}1.8 and {approx}1.0 mJ/eV sr ({approx}0.4 and 0.25 J/A sr), respectively, for 220 J, 10 ps laser irradiation.

  17. Dual-energy imaging of bone marrow edema on a dedicated multi-source cone-beam CT system for the extremities

    NASA Astrophysics Data System (ADS)

    Zbijewski, W.; Sisniega, A.; Stayman, J. W.; Thawait, G.; Packard, N.; Yorkston, J.; Demehri, S.; Fritz, J.; Siewerdsen, J. H.

    2015-03-01

    Purpose: Arthritis and bone trauma are often accompanied by bone marrow edema (BME). BME is challenging to detect in CT due to the overlaying trabecular structure but can be visualized using dual-energy (DE) techniques to discriminate water and fat. We investigate the feasibility of DE imaging of BME on a dedicated flat-panel detector (FPD) extremities cone-beam CT (CBCT) with a unique x-ray tube with three longitudinally mounted sources. Methods: Simulations involved a digital BME knee phantom imaged with a 60 kVp low-energy beam (LE) and 105 kVp high-energy beam (HE) (+0.25 mm Ag filter). Experiments were also performed on a test-bench with a Varian 4030CB FPD using the same beam energies as the simulation study. A three-source configuration was implemented with x-ray sources distributed along the longitudinal axis and DE CBCT acquisition in which the superior and inferior sources operate at HE (and collect half of the projection angles each) and the central source operates at LE. Three-source DE CBCT was compared to a double-scan, single-source orbit. Experiments were performed with a wrist phantom containing a 50 mg/ml densitometry insert submerged in alcohol (simulating fat) with drilled trabeculae down to ~1 mm to emulate the trabecular matrix. Reconstruction-based three-material decomposition of fat, soft tissue, and bone was performed. Results: For a low-dose scan (36 mAs in the HE and LE data), DE CBCT achieved combined accuracy of ~0.80 for a pattern of BME spherical lesions ranging 2.5 - 10 mm diameter in the knee phantom. The accuracy increased to ~0.90 for a 360 mAs scan. Excellent DE discrimination of the base materials was achieved in the experiments. Approximately 80% of the alcohol (fat) voxels in the trabecular phantom was properly identified both for single and 3-source acquisitions, indicating the ability to detect edemous tissue (water-equivalent plastic in the body of the densitometry insert) from the fat inside the trabecular matrix

  18. Dual-wavelength source from 5%MgO:PPLN cylinders for the characterization of nonlinear infrared crystals.

    PubMed

    Kemlin, Vincent; Jegouso, David; Debray, Jérôme; Boursier, Elodie; Segonds, Patricia; Boulanger, Benoit; Ishizuki, Hideki; Taira, Takunori; Mennerat, Gabriel; Melkonian, Jean-Michel; Godard, Antoine

    2013-11-18

    We conceived a unique fully parametric source based on two independent cylindrical OPOs simultaneously pumped by the same Nd:YAG laser. Each OPO delivers more than 2 mJ and is continuously tunable between 1.41 µm and 4.3 µm. This source is of particular interest for the study of the generation of infrared parametric light in nonlinear crystals. It was validated by performing difference frequency generation experiments in CdSe crystals with output in the range 8 - 10 µm.

  19. Compact high-repetition-rate terahertz source based on difference frequency generation from an efficient 2-μm dual-wavelength KTP OPO

    NASA Astrophysics Data System (ADS)

    Mei, Jialin; Zhong, Kai; Wang, Maorong; Liu, Pengxiang; Xu, Degang; Wang, Yuye; Shi, Wei; Yao, Jianquan; Norwood, Robert A.; Peyghambarian, Nasser

    2016-11-01

    A compact optical terahertz (THz) source was demonstrated based on an efficient high-repetition-rate doubly resonant optical parametric oscillator (OPO) around 2 μm with two type-II phase-matched KTP crystals in the walk-off compensated configuration. The KTP OPO was intracavity pumped by an acousto-optical (AO) Q-switched Nd:YVO4 laser and emitted two tunable wavelengths near degeneracy. The tuning range extended continuously from 2.068 μm to 2.191 μm with a maximum output power of 3.29 W at 24 kHz, corresponding to an optical-optical conversion efficiency (from 808 nm to 2 μm) of 20.69%. The stable pulsed dual-wavelength operation provided an ideal pump source for generating terahertz wave of micro-watt level by the difference frequency generation (DFG) method. A 7.84-mm-long periodically inverted quasi-phase-matched (QPM) GaAs crystal with 6 periods was used to generate a terahertz wave, the maximum voltage of 180 mV at 1.244 THz was acquired by a 4.2-K Si bolometer, corresponding to average output power of 0.6 μW and DFG conversion efficiency of 4.32×10-7. The acceptance bandwidth was found to be larger than 0.35 THz (FWHM). As to the 15-mm-long GaSe crystal used in the type-II collinear DFG, a tunable THz source ranging from 0.503 THz to 3.63 THz with the maximum output voltage of 268 mV at 1.65 THz had been achieved, and the corresponding average output power and DFG conversion efficiency were 0.9 μW and 5.86×10-7 respectively. This provides a potential practical palm-top tunable THz sources for portable applications.

  20. An increase of curdlan productivity by integration of carbon/nitrogen sources control and sequencing dual fed-batch fermentors operation.

    PubMed

    Zheng, Z Y; Jiang, Y; Zhan, X B; Ma, L W; Wu, J R; Zhang, L M; Lin, C C

    2014-01-01

    Curdlan is produced by Agrobacterium sp. ATCC 31749 under nitrogen-limited conditions not associated with cell growth. A novel curdlan production process was developed based on the different nutrient requirements for microbial cell growth and its efficiency was increased by integrating carbon/nitrogen sources control and sequencing dual fed-batch fermentors operation. By feeding ammonium solution to supply abundant nitrogen source and controlling pH in Fermentor I, cell growth was accelerated. High cell density of 29 g/L was attained. The culture broth in Fermentor I was then inoculated into sequencing Fermentor II which alleviated the high requirement for dissolved oxygen and accumulation of inhibitory metabolic by-products during curdlan production. Fermentor I promoted cell growth. Curdlan production started instantaneously in Fermentor II. By feeding nutrient solution with high carbon/nitrogen ratio and NaOH solution for pH adjustment, a feasible and optimal curdlan production process was formulated. The productivity, conversion efficiency and curdlan yield were achieved of 0.98 g/(L h), 57% (w) and 67 g/L, respectively. Such novel process can be scaled up for significant cost reduction at the industrial level.

  1. Implementation and performance of SIBYLS: a dual endstation small-angle X-ray scattering and macromolecular crystallography beamline at the Advanced Light Source

    PubMed Central

    Classen, Scott; Hura, Greg L.; Holton, James M.; Rambo, Robert P.; Rodic, Ivan; McGuire, Patrick J.; Dyer, Kevin; Hammel, Michal; Meigs, George; Frankel, Kenneth A.; Tainer, John A.

    2013-01-01

    The SIBYLS beamline (12.3.1) of the Advanced Light Source at Lawrence Berkeley National Laboratory, supported by the US Department of Energy and the National Institutes of Health, is optimized for both small-angle X-ray scattering (SAXS) and macromolecular crystallography (MX), making it unique among the world’s mostly SAXS or MX dedicated beamlines. Since SIBYLS was commissioned, assessments of the limitations and advantages of a combined SAXS and MX beamline have suggested new strategies for integration and optimal data collection methods and have led to additional hardware and software enhancements. Features described include a dual mode monochromator [containing both Si(111) crystals and Mo/B4C multilayer elements], rapid beamline optics conversion between SAXS and MX modes, active beam stabilization, sample-loading robotics, and mail-in and remote data collection. These features allow users to gain valuable insights from both dynamic solution scattering and high-resolution atomic diffraction experiments performed at a single synchrotron beamline. Key practical issues considered for data collection and analysis include radiation damage, structural ensembles, alternative conformers and flexibility. SIBYLS develops and applies efficient combined MX and SAXS methods that deliver high-impact results by providing robust cost-effective routes to connect structures to biology and by performing experiments that aid beamline designs for next generation light sources. PMID:23396808

  2. A dual-inexact fuzzy stochastic model for water resources management and non-point source pollution mitigation under multiple uncertainties

    NASA Astrophysics Data System (ADS)

    Dong, C.; Tan, Q.; Huang, G.-H.; Cai, Y.-P.

    2014-01-01

    In this research, a dual-inexact fuzzy stochastic programming (DIFSP) method was developed for supporting the planning of water and farmland use management system considering the non-point source pollution mitigation under uncertainty. The random boundary interval (RBI) was incorporated into DIFSP through integrating fuzzy programming (FP) and chance-constrained programming (CCP) approaches within an interval linear programming (ILP) framework. The lower and upper bounds of RBI are continuous random variables, and the correlation exiting between the lower and upper bounds can be tackled in RBI through the joint probability distribution function. And thus the subjectivity of decision making is greatly reduced, enhancing the stability and robustness of obtained solutions. The proposed method was then applied to solve a water and farmland use planning model (WFUPM) with non-point source pollution. The generated results could provide decision makers with detailed water supply-demand schemes involving diversified water related activities under various system conditions. These useful solutions could allow more in-depth analyses of the trade-offs between human and environment, as well as those between system optimality and reliability. In addition, comparative analyses on the solutions obtained from ICCP (Interval chance-constraints programming) and DIFSP demonstrated the higher application of this developed approach for supporting the water and farmland use system planning.

  3. A dual-inexact fuzzy stochastic model for water resources management and non-point source pollution mitigation under multiple uncertainties

    NASA Astrophysics Data System (ADS)

    Dong, C.; Tan, Q.; Huang, G.-H.; Cai, Y.-P.

    2014-05-01

    In this research, a dual-inexact fuzzy stochastic programming (DIFSP) method was developed for supporting the planning of water and farmland use management system considering the non-point source pollution mitigation under uncertainty. The random boundary interval (RBI) was incorporated into DIFSP through integrating fuzzy linear programming (FLP) and chance-constrained programming (CCP) approaches within an interval linear programming (ILP) framework. This developed method could effectively tackle the uncertainties expressed as intervals and fuzzy sets. Moreover, the lower and upper bounds of RBI are continuous random variables, and the correlation existing between the lower and upper bounds can be tackled in RBI through the joint probability distribution function. And thus the subjectivity of decision making is greatly reduced, enhancing the stability and robustness of obtained solutions. The proposed method was then applied to solve a water and farmland use planning model (WFUPM) with non-point source pollution mitigation. The generated results could provide decision makers with detailed water supply-demand schemes involving diversified water-related activities under preferred satisfaction degrees. These useful solutions could allow more in-depth analyses of the trade-offs between humans and environment, as well as those between system optimality and reliability. In addition, comparative analyses on the solutions obtained from ICCP (Interval chance-constraints programming) and DIFSP demonstrated the higher application of this developed approach for supporting the water and farmland use system planning.

  4. Bilateral breast MRI by use of dual-source parallel radiofrequency excitation and image-based shimming at 3 Tesla: improvement in homogeneity on fat-suppression imaging.

    PubMed

    Ishizaka, Kinya; Kato, Fumi; Terae, Satoshi; Mito, Suzuko; Oyama-Manabe, Noriko; Kamishima, Tamotsu; Nakanishi, Mitsuhiro; Sugimori, Hiroyuki; Hamaguchi, Hiroyuki; Shirato, Hiroki

    2015-01-01

    In this study, we aimed to compare fat-suppression homogeneity on breast MR imaging by using dual-source parallel radiofrequency excitation and image-based shimming (DS-IBS) with single-source radiofrequency excitation with volume shim (SS-Vol) at 3 Tesla. Twenty patients were included. Axial three-dimensional T1-weighted turbo-field-echo breast images with DS-IBS and SS-Vol were obtained. Fat suppression was scored with four grade points. The contrast of the pectoral muscle and the fat in each breast area was obtained in the head medial, head lateral, foot medial, and foot lateral areas. The axillary space was calculated and compared between DS-IBS and SS-Vol. The average DS-IBS score was significantly higher than that of SS-Vol. The mean contrasts of fat in the foot lateral areas and axillary spaces on DS-IBS images were significantly higher than on SS-Vol images.

  5. Design and analysis of a dual-axis resonator fiber-optic gyroscope employing a single source.

    PubMed

    Pinnoji, Prerana Dabral; Nayak, Jagannath

    2013-08-01

    In this paper, design of a resonator fiber-optic gyroscope comprised of a single laser source and two optical fiber resonator rings is presented. A typical gyroscope measures angular rotation around a fixed axis, whereas the proposed design can sense simultaneous rotation about two orthogonal axes. Two variants of the design are proposed and analyzed using a mathematical model based on Jones matrix methodology.

  6. Land-use controls on sources and processing of nitrate in small watersheds: Insights from dual isotopic analysis

    USGS Publications Warehouse

    Barnes, R.T.; Raymond, P.A.

    2010-01-01

    Studies have repeatedly shown that agricultural and urban areas export considerably more nitrogen to streams than forested counterparts, yet it is difficult to identify and quantify nitrogen sources to streams due to complications associated with terrestrial and in-stream biogeochemical processes. In this study, we used the isotopic composition of nitrate (??15N-NO3- and ??18O- NO3-) in conjunction with a simple numerical model to examine the spatial and temporal variability of nitrate (NO3-) export across a land-use gradient and how agricultural and urban development affects net removal mechanisms. In an effort to isolate the effects of land use, we chose small headwater systems in close proximity to each other, limiting the variation in geology, surficial materials, and climate between sites. The ??15N and ??18Oof stream NO 3- varied significantly between urban, agricultural, and forested watersheds, indicating that nitrogen sources are the primary determinant of the ??15N-NO3-, while the ??18O-NO3- was found to reflect biogeochemical processes. The greatest NO3- concentrations corresponded with the highest stream ??15N-NO3- values due to the enriched nature of two dominant anthropogenic sources, septic and manure, within the urban and agricultural watersheds, respectively. On average, net removal of the available NO3- pool within urban and agricultural catchments was estimated at 45%. The variation in the estimated net removal of NO3- from developed watersheds was related to both drainage area and the availability of organic carbon. The determination of differentiated isotopic land-use signatures and dominant seasonal mechanisms illustrates the usefulness of this approach in examining the sources and processing of excess nitrogen within headwater catchments. ?? 2010 by the Ecological Society of America.

  7. [Linkage of large secondary and registry data sources with data of cohort studies : usage of a dual potential].

    PubMed

    Jacobs, Svenja; Stallmann, Christoph; Pigeot, Iris

    2015-08-01

    Cohort studies provide the best evidence of all epidemiological observational studies for the identification of causal relationships between risk factors and diseases. However, this design may lead to drawbacks that may affect the validity and reliability of the results. This follows in particular from systematic errors, such as selection bias or recall bias. One possibility to avoid or counteract some of these drawbacks is to link primary data from cohort studies with secondary and register data. The linkage of these data may also be used for mutual validations. Data that were previously linked with primary data within the context of cohort studies in Germany were obtained from statutory health insurances and pensions as well as data from the Federal Employment Agency and cancer registries. All these data have two features in common: First, they all cover detailed information about a large population and over a long period of time. Second, all sources are in principle able to provide data on an individual level such that an individual data linkage, e.g. with primary data, is possible. However, use and linkage of each of these data sources are restricted by several limitations. These have to be accounted for as well as numerous legal restrictions that exist in Germany to especially prevent the misuse of social data.

  8. Analysis of Dual Rotating Rake Data from the NASA Glenn Advanced Noise Control Fan Duct with Artificial Sources

    NASA Technical Reports Server (NTRS)

    Dahl, Milo D.; Sutliff, Daniel L.

    2014-01-01

    The Rotating Rake mode measurement system was designed to measure acoustic duct modes generated by a fan stage. Initially, the mode amplitudes and phases were quantified from a single rake measurement at one axial location. To directly measure the modes propagating in both directions within a duct, a second rake was mounted to the rotating system with an offset in both the axial and the azimuthal directions. The rotating rake data analysis technique was then extended to include the data measured by the second rake. The analysis resulted in a set of circumferential mode levels at each of the two rake microphone locations. Radial basis functions were then least-squares fit to this data to obtain the radial mode amplitudes for the modes propagating in both directions within the duct. Validation experiments have been conducted using artificial acoustic sources. Results are shown for the measurement of the standing waves in the duct from sound generated by one and two acoustic sources that are separated into the component modes propagating in both directions within the duct. Measured reflection coefficients from the open end of the duct are compared to analytical predictions.

  9. Dual functionality of triticale as a novel dietary source of prebiotics with antioxidant activity in fermented dairy products.

    PubMed

    Agil, Rania; Hosseinian, Farah

    2012-03-01

    The objectives of this study were to: (i) define the optimum concentration of triticale bran (TB) that can be incorporated in yogurt, (ii) evaluate the prebiotic effects of TB on microbial viability, pH and total titratable acidity (TTA) in yogurt across 28 days of cold storage, and (iii) measure the oxygen radical absorbance capacity (ORAC) of water-extractable polysaccharides (WEP) in TB. Lactobacillus bulgaricus and Streptococcus thermophilus were used as starter cultures. Lactobacillus acidophilus and Bifidobacterium lactis were used as probiotics. A concentration of 4% TB in yogurt was determined to be the maximum amount that could be added without causing synersis. By day 7, the number of bacteria greatly increased in yogurt samples containing TB and maintained higher viable bacteria counts at the end of the cold storage period, in comparison to controls (P ≤ 0.05). Confirming this data was the lower pH levels and higher TTA values of TB yogurt samples exhibited throughout 28 days (P ≤ 0.05). Polysaccharide extracts of TB exhibited strong antioxidant activity with an ORAC value of 33.86 ± 2.30 μmol trolox equivalents (TE)/g of bran. Results of this study suggest that TB may serve as a new prebiotic and antioxidant source for functional foods and nutraceutical applications.

  10. Terahertz source at 9.4 THz based on a dual-wavelength infrared laser and quasi-phase matching in organic crystals OH1

    SciTech Connect

    Majkić, A. Zgonik, M.; Petelin, A.; Jazbinšek, M.; Ruiz, B.; Medrano, C.; Günter, P.

    2014-10-06

    We present a compact, room temperature, and narrowband terahertz source, based on difference-frequency generation in the organic nonlinear optical crystals OH1 (2-[3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene]malononitrile). The system employs a specific dual-wavelength infrared laser that emits coaxial, synchronous 10-ns pulses of similar energy and duration at wavelengths of 1064 nm and 1030 nm by using Nd:YAG and Yb:YAG crystals within the split laser cavity. The common part of the laser cavity comprises an acousto-optic Q-switch and an output coupler. The output is frequency-mixed in a stack of several OH1 crystals in a quasi-phase-matching configuration, which is determined on the basis of refractive index and absorption measurements in the 1–11 THz range. The system generates terahertz radiation in pulse trains with 1.0 μW average power and a near-Gaussian intensity profile.

  11. Assessing sources of nitrate contamination in the Shiraz urban aquifer (Iran) using the δ(15)N and δ(18)O dual-isotope approach.

    PubMed

    Amiri, Haleh; Zare, Mohammad; Widory, David

    2015-01-01

    Nitrate ([Formula: see text]) is one of the major threats to the quality of the drinking water taken from the Shiraz aquifer. This aquifer undergoes high anthropogenic pressures from multiple local urban (including uncontrolled sewage systems), agricultural and industrial activities, resulting in [Formula: see text] concentrations as high as 149 mg L(-1), well above the 50 mg L(-1) guideline defined by the World Health Organisation. We coupled here classical chemical and dual isotope (δ(15)N and δ(18)O of [Formula: see text]) approaches trying to characterize sources and potential processes controlling the budget of this pollutant. Chemical data indicate that nitrate in this aquifer is explained by distinct end-members: while mineral fertilizers isotopically show to have no impact, our isotope approach identifies natural soil nitrification and organic [Formula: see text] (manure and/or septic waste) as the two main contributors. Isotope data suggest that natural denitrification may occur within the aquifer, but this conclusion is not supported by the study of other chemical parameters.

  12. Assessing the sources and magnitude of diurnal nitrate variability in the San Joaquin River (California) with an in situ optical nitrate sensor and dual nitrate isotopes

    USGS Publications Warehouse

    Pellerin, B.A.; Downing, B.D.; Kendall, C.; Dahlgren, R.A.; Kraus, T.E.C.; Saraceno, J.; Spencer, R.G.M.; Bergamaschi, B.A.

    2009-01-01

    1. We investigated diurnal nitrate (NO3-) concentration variability in the San Joaquin River using an in situ optical NO3- sensor and discrete sampling during a 5-day summer period characterized by high algal productivity. Dual NO3- isotopes (??15NNO3 and ??18O NO3) and dissolved oxygen isotopes (??18O DO) were measured over 2 days to assess NO3- sources and biogeochemical controls over diurnal time-scales. 2. Concerted temporal patterns of dissolved oxygen (DO) concentrations and ??18ODO were consistent with photosynthesis, respiration and atmospheric O2 exchange, providing evidence of diurnal biological processes independent of river discharge. 3. Surface water NO3- concentrations varied by up to 22% over a single diurnal cycle and up to 31% over the 5-day study, but did not reveal concerted diurnal patterns at a frequency comparable to DO concentrations. The decoupling of ??15NNO3 and ??18ONO3 isotopes suggests that algal assimilation and denitrification are not major processes controlling diurnal NO3- variability in the San Joaquin River during the study. The lack of a clear explanation for NO 3- variability likely reflects a combination of riverine biological processes and time-varying physical transport of NO3- from upstream agricultural drains to the mainstem San Joaquin River. 4. The application of an in situ optical NO3- sensor along with discrete samples provides a view into the fine temporal structure of hydrochemical data and may allow for greater accuracy in pollution assessment. ?? 2008 Blackwell Publishing Ltd.

  13. 3T MRI and 128-slice dual-source CT cisternography images of the cranial nerves a brief pictorial review for clinicians.

    PubMed

    Roldan-Valadez, Ernesto; Martinez-Anda, Jaime J; Corona-Cedillo, Roberto

    2014-01-01

    There is a broad community of health sciences professionals interested in the anatomy of the cranial nerves (CNs): specialists in neurology, neurosurgery, radiology, otolaryngology, ophthalmology, maxillofacial surgery, radiation oncology, and emergency medicine, as well as other related fields. Advances in neuroimaging using high-resolution images from computed tomography (CT) and magnetic resonance (MR) have made highly-detailed visualization of brain structures possible, allowing normal findings to be routinely assessed and nervous system pathology to be detected. In this article we present an integrated perspective of the normal anatomy of the CNs established by radiologists and neurosurgeons in order to provide a practical imaging review, which combines 128-slice dual-source multiplanar images from CT cisternography and 3T MR curved reconstructed images. The information about the CNs includes their origin, course (with emphasis on the cisternal segments and location of the orifices at the skull base transmitting them), function, and a brief listing of the most common pathologies affecting them. The scope of the article is clinical anatomy; readers will find specialized texts presenting detailed information about particular topics. Our aim in this article is to provide a helpful reference for understanding the complex anatomy of the cranial nerves.

  14. Comparison of Image Quality, Diagnostic Accuracy and Radiation Dose Between Flash Model and Retrospective ECG-Triggered Protocols in Dual Source Computed Tomography (DSCT) in Congenital Heart Diseases

    PubMed Central

    Wang, Rong; Xu, Xiang-Jiu; Huang, Gang; Zhou, Xing; Zhang, Wen-Wen; Ma, Ya-Qiong; Zuo, Xiao-na

    2017-01-01

    Summary Background Dual source computed tomography (DSCT) plays an important role in the diagnosis of congenital heart diseases (CHD). However, the issue of radiation-related side effects constitutes a wide public concern. The aim of the study was to explore the differences in diagnostic accuracy, radiation dose and image quality between a prospectively ECG – triggered high – pitch spiral acquisition (flash model) and a retrospective ECG-gated protocol of DSCT used for the detection of CHD. Material/Methods The study included 58 patients with CHD who underwent a DSCT examination, including two groups of 29 patients in each protocol. Then, both subjective and objective image quality, diagnostic accuracy and radiation dose were compared between the two protocols. Results The image quality and the total as well as partial diagnostic accuracy did not differ significantly between the protocols. The radiation dose in the flash model was obviously lower than that in the retrospective model (P<0.05). Conclusions Compared to the retrospective protocol, the flash model can significantly reduce the dose of radiation, while maintaining both diagnostic accuracy and image quality. PMID:28344686

  15. Modulations of the plasma uniformity by low frequency sources in a large-area dual frequency inductively coupled plasma based on fluid simulations

    SciTech Connect

    Sun, Xiao-Yan; Zhang, Yu-Ru; Li, Xue-Chun; Wang, You-Nian

    2015-05-15

    As the wafer size increases, dual frequency (DF) inductively coupled plasma (ICP) sources have been proposed as an effective method to achieve large-area uniform plasma processing. A two-dimensional (2D) self-consistent fluid model, combined with an electromagnetic module, has been employed to investigate the influence of the low frequency (LF) source on the plasma radial uniformity in an argon DF discharge. When the DF antenna current is fixed at 10 A, the bulk plasma density decreases significantly with the LF due to the less efficient heating, and the best radial uniformity is obtained at 3.39 MHz. As the LF decreases to 2.26 MHz, the plasma density is characterized by an edge-high profile, and meanwhile the maximum of the electron temperature appears below the outer two-turn coil. Moreover, the axial ion flux at 3.39 MHz is rather uniform in the center region except at the radial edge of the substrate, where a higher ion flux is observed. When the inner five-turn coil frequency is fixed at 2.26 MHz, the plasma density profiles shift from edge-high over uniform to center-high as the LF coil current increases from 6 A to 18 A, and the best plasma uniformity is obtained at 14 A. In addition, the maximum of the electron temperature becomes lower with a second peak appears at the radial position of r = 9 cm at 18 A.

  16. Fiber laser driven dual photonic crystal fiber femtosecond mid-infrared source tunable in the range of 4.2 to 9 μm

    NASA Astrophysics Data System (ADS)

    Yao, Yuhong; Knox, Wayne H.

    2014-02-01

    We report a fiber based approach to broadly tunable femtosecond mid-IR source based on difference frequency mixing of the outputs from dual photonic crystal fibers (PCF) pumped by a femtosecond fiber laser, which is a custom-built Yb-doped fiber chirped pulse amplifier (CPA) delivering 1.35 W, 300 fs, 40 MHz pulses centered at 1035 nm. The CPA output is split into two arms to pump two different types of PCFs for generation of the spectrally separated pulses. The shorter wavelength pulses are generated in one PCF with its single zero dispersion wavelength (ZDW) at 1040 nm. Low normal dispersion around the pumping wavelength enables spectral broadening dominated by self-phase modulation (SPM), which extends from 970 to 1092 nm with up to 340 mW of average power. The longer wavelength pulses are generated in a second PCF which has two closely spaced ZDWs around the laser wavelength. Facilitated by its special dispersion profile, the laser wavelength is converted to the normal dispersion region of the fiber, leading to the generation of the narrow-band intense Stokes pulses with 1 to 1.25 nJ of pulse energy at a conversion efficiency of ~30% from the laser pulses. By difference mixing the outputs from both PCFs in a type-II AgGaS2 crystal, mid-IR pulses tunable from 4.2 to 9 μm are readily generated with its average power ranging from 135 - 640 μW, corresponding to 3 - 16 pJ of pulse energy which is comparable to the reported fiber based mid-IR sources enabled by the solitons self-frequency shift (for example, 3 - 10 μm with 10 pJ of maximum pulse energy in [10]). The reported approach provides a power-scalable route to the generation of broadly tunable femtosecond mid-IR pulses, which we believe to be a promising solution for developing compact, economic and high performance mid-IR sources.

  17. Dual stable isotopic analysis of nitrogen and oxygen to evaluate sources and sinks of atmospheric anthropogenic nitrate in the Colorado Desert

    NASA Astrophysics Data System (ADS)

    Bell, M. D.; Allen, E. B.; Sickman, J. O.

    2010-12-01

    Industrial, automotive, and agricultural emissions release nitrogen into the atmosphere which is subsequently deposited to the surrounding terrestrial ecosystem. The Colorado Desert is impacted by nitrogen deposition from the west due to inputs from the Los Angeles air basin as well as nearby sources from agriculture in the Coachella Valley (CV). Current research within the Colorado Desert has demonstrated that anthropogenic N deposition contributes to the increased biomass of exotic invasive grasses, which compete with native species and can create enough biomass to carry fire in areas of high deposition. To measure the anthropogenic nitrogen within the CV, an array of passive air samplers was erected spanning the valley from west to east. Each sampler contained filters to passively collect both nitric acid and ammonia ions. To evaluate the degree to which the local ecosystem is supplemented by atmospheric N and determine how nitrogen pools are transformed, surface soil and leaf tissue of the dominant shrub, Larrea tridentata, were collected at each site. Only nitrate data from the samplers has currently been analyzed. δ15N, δ17O, and δ18O were obtained from atmospheric and 1M KCl soil extracts using dual isotopic analysis of NO3-. δ15N of vegetation was obtained through combustion of dried leaf tissue. The highest concentrations of atmospheric nitrate are located on the western edge of the desert in the direction toward Los Angeles, and there is also high nitrate near the Salton Sea. The isoscape produced by the isotopic analysis provides a map further describing how NO3- molecules are moving through the desert. This map shows which sources are influencing deposition sinks across the valley. Soil concentrations of nitrogen increase along the same gradient and have an inverse relationship with δ15N. Plant tissue is also less enriched in δ15N at high deposition sites, which correlates with soil values and may be caused by increased fractionation of nitrogen

  18. High-pitch dual-source CT coronary angiography: analysis of the impact on image quality of altered electrocardiography waves during data acquisition.

    PubMed

    Wang, Xiaoling; Fang, Jiliang; Tong, Haibin; Zhao, Qing; Song, Qingqiao; Luo, Ping; Xue, Chao; Zhang, Min; Yang, Shuhua; Wang, Qun; Wang, Ping; Shi, Fengxiang; Xu, Lei; Rong, Peijing

    2012-06-01

    Electrocardiography (ECG) "altered waves" sometimes occur during data acquisition when computed tomography coronary angiography (CTCA) is performed with the prospectively ECG-triggered high-pitch (Flash spiral) mode using a second-generation dual-source CT. The aim of this study was to assess the effect of the ECG altered waves on image quality. Seventy-three consecutive patients with stable sinus rhythm ≤ 65 beats per minute were retrospectively enrolled in this study. CTCA was performed using the Flash spiral mode in which the data acquisition was prospectively triggered at 60 % of the R-R interval and completed within one cardiac cycle. The ECG waves before and during data acquisition were analyzed for grouping purposes. Image quality was evaluated using a four-point scale (1 = best, 4 = unevaluatable). Thirty patients (group 1) were found to have ECG altered waves during data acquisition, while 43 patients (group 2) had ECG "stable waves." The altered waves were seen as the baseline drifting; the broad, erected, or inverted P wave or QRS complexes; and a new wave. However, the length of the R-R interval did not change during the data acquisition. There were no significant differences in image quality scores between the two groups on the per-patient (2 ± 0.87 vs. 2.2 ± 0.74, P = 0.273) or per-segment (1.27 ± 0.54 vs. 1.32 ± 0.55, P = 0.577) basis. There were no significant differences in coronary evaluatability as well (per-patient; 93.3 vs. 95.3 %, P = 0.352; per-segment; 99.4 vs. 99.6 %, P = 1.0). CTCA image quality is not affected by ECG altered waves during data acquisition using the Flash spiral mode in low and stable heart rate patients. Thus, the ECG altered waves are considered artifacts.

  19. A multireader diagnostic performance study of low-contrast detectability on a third-generation dual-source CT scanner: filtered back projection versus advanced modeled iterative reconstruction

    NASA Astrophysics Data System (ADS)

    Solomon, Justin; Mileto, Achille; Ramirez-Giraldo, Juan Carlos; Samei, Ehsan

    2015-03-01

    The purpose of this work was to compare CT low-contrast detectability between two reconstruction algorithms, filtered back-projection (FBP) and advanced modeled iterative reconstruction (ADMIRE). A phantom was designed with a range of low-contrast circular inserts representing 5 contrast levels and 3 sizes. The phantom was imaged on a third-generation dual-source CT scanner (SOMATOM Definition Force, Siemens Healthcare) under various dose levels (0.74 - 5.8 mGy CTDIVol). Images were reconstructed using different settings of slice thickness (0.6 - 5 mm) and reconstruction algorithms (FBP and ADMIRE with strength of 3-5) and were assessed by eleven blinded and independent readers using a two alternative forced choice (2AFC) detection experiment. A second observer experiment was further performed in which observers scored the images based on the total number of visible object groups. Detection performance increased with increasing contrast, size, dose, with accuracy ranging from 50% (i.e., guessing) to 87% with an average inter-observer variability of ±7%. The use of ADMIRE-3 increased performance by 5.2% resulting in an estimated dose reduction potential of 56-60%. The results from the second experiment also showed increased number of visible object groups for increasing dose, slice thickness, and ADMIRE strength. The score difference between FBP and ADMIRE was 0.9, 1.3, and 2.1 for ADMIRE strengths of 3, 4, and 5, respectively, resulting in estimated dose reduction potentials between 4-80%. Overall, the data indicated potential to image at reduced doses while maintaining comparable image quality when using ADMIRE compared to FBP.

  20. Update on multidetector coronary CT angiography of coronary stents: in vitro evaluation of 29 different stent types with dual-source CT.

    PubMed

    Maintz, David; Burg, Matthias C; Seifarth, Harald; Bunck, Alexander C; Ozgün, Murat; Fischbach, Roman; Jürgens, Kai Uwe; Heindel, Walter

    2009-01-01

    The aim of this study was to test a large sample of the latest coronary artery stents using four image reconstruction approaches with respect to lumen visualization, lumen attenuation, and image noise in dual-source multidetector row CT (DSCT) in vitro and to provide a CT catalogue of currently used coronary artery stents. Twenty-nine different coronary artery stents (19 steel, 6 cobalt-chromium, 2 tantalum, 1 iron, 1 magnesium) were examined in a coronary artery phantom (vessel diameter 3 mm, intravascular attenuation 250 HU, extravascular density -70 HU). Stents were imaged in axial orientation with standard parameters: 32 x 0.6 collimation, pitch 0.24, 400 mAs, 120 kV, rotation time 0.33 s. Image reconstructions were obtained with four different convolution kernels (soft, medium-soft, standard high-resolution, stent-dedicated). To evaluate visualization characteristics of the stent, the lumen diameter, intraluminal density, and noise were measured. The stent-dedicated kernel offered best average lumen visualization (54 +/- 8.3%) and most realistic lumen attenuation (222 +/- 44 HU) at the expense of increased noise (23.9 +/- 1.9 HU) compared with standard CTA protocols (p < 0.001 for all). The magnesium stent showed the least artifacts with a lumen visibility of 90%. The majority of stents (79%) exhibited a lumen visibility of 50-59%. Less than half of the stent lumen was visible in only six stents. Stent lumen visibility largely varies depending on the stent type. Magnesium is by far more favorable a stent material with regard to CT imaging when compared with the more common materials steel, cobalt-chromium, or tantalum. The magnesium stent exhibits a lumen visibility of 90%, whereas the majority of the other stents exhibit a lumen visibility of 50-59%.

  1. Measurement of the ascending aorta diameter in patients with severe bicuspid and tricuspid aortic valve stenosis using dual-source computed tomography coronary angiography.

    PubMed

    Son, Jee Young; Ko, Sung Min; Choi, Jin Woo; Song, Meong Gun; Hwang, Hweung Kon; Lee, Sook Jin; Kang, Joon-Won

    2011-12-01

    We aimed to evaluate the diagnostic performance of dual-source computed tomography coronary angiography (DSCT-CA) in the measurement of the ascending aorta (AA) diameter and compare the AA diameter in patients with severe bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV) stenosis. Eighty-eight consecutive patients (50 men, mean age 60.3 ± 13 year) with severe aortic stenosis (AS) underwent DSCT-CA before aortic valve surgery. Seventy-four of the 88 patients underwent cardiovascular magnetic resonance (CMR). The internal diameter of AA was measured from early-systole with DSCT-CA and CMR by 2 radiologists independently at 4 levels (aortic annulus, sinuses of Valsalva, sinotubular junction, and tubular portion at the right pulmonary artery). The patients were divided in to 2 groups (BAV [n = 53]; TAV [n = 35]) according to operative findings. Patients with BAV were significantly younger than those with TAV (P = 0.0035). Inter-observer agreement of AA diameters at 4 levels with DSCT-CA and CMR was excellent (intraclass correlation coefficient = 0.89-0.97). Also, the DSCT-CA and CMR measurements of the AA diameter strongly correlated (r = 0.871-0.976). Mean diameter of the AA by DSCT-CA was significantly larger in patients with BAV (34.4 ± 8.2 mm) as compared to those with TAV (30.6 ± 5.5 mm). The diameters at the sinuses of Valsalva, sinotubular junction, and tubular portion were significantly larger in BAV than in TAV. Twenty-two of 53 (41.5%) patients with BAV and 2 of 35 (5.7%) patients with TAV had AA dilatation > 45 mm. DSCT-CA allows accurate assessment of the AA diameters in patients with severe AS. Patients with severe BAV stenosis had larger AA diameters and higher prevalence of AA dilatation > 45 mm as compared to those with severe TAV stenosis.

  2. Quantification of left coronary bifurcation angles and plaques by coronary computed tomography angiography for prediction of significant coronary stenosis: A preliminary study with dual-source CT

    PubMed Central

    Cui, Yue; Zeng, Wenjuan; Yu, Jie; Lu, Jing; Hu, Yuannan; Diao, Nan; Liang, Bo; Han, Ping; Shi, Heshui

    2017-01-01

    Purpose To evaluate the diagnostic performance of left coronary bifurcation angles and plaque characteristics for prediction of coronary stenosis by dual-source CT. Methods 106 patients suspected of coronary artery disease undergoing both coronary computed tomography angiography (CCTA) and invasive coronary angiography (CAG) within three months were included. Left coronary bifurcation angles including the angles between the left anterior descending artery and left circumflex artery (LAD-LCx), left main coronary artery and left anterior descending artery (LM-LAD), left main coronary artery and left circumflex artery (LM-LCx) were measured on CT images. CCTA plaque parameters were calculated by plaque analysis software. Coronary stenosis ≥ 50% by CAG was defined as significant. Results 106 patients with 318 left coronary bifurcation angles and 126 vessels were analyzed. The bifurcation angle of LAD-LCx was significantly larger in left coronary stenosis ≥ 50% than stenosis < 50%, and significantly wider in the non-calcified plaque group than calcified. Multivariable analyses showed the bifurcation angle of LAD-LCx was an independent predictor for significant left coronary stenosis (OR = 1.423, P = 0.002). In ROC curve analysis, LAD-LCx predicted significant left coronary stenosis with a sensitivity of 66.7%, specificity of 78.4%, positive predictive value of 85.2% and negative predictive value of 55.8%. The lipid plaque volume improved the diagnostic performance of CCTA diameter stenosis (AUC: 0.854 vs. 0.900, P = 0.045) in significant coronary stenosis. Conclusions The bifurcation angle of LAD-LCx could predict significant left coronary stenosis. Wider LAD-LCx is related to non-calcified lesions. Lipid plaque volume could improve the diagnostic performance of CCTA for coronary stenosis prediction. PMID:28346530

  3. Image quality and radiation dose of 128-slice dual-source CT venography using low kilovoltage combined with high-pitch scanning and automatic tube current modulation.

    PubMed

    Park, Chan Kue; Choo, Ki Seok; Jeon, Ung Bae; Baik, Seung Kug; Kim, Yong Woo; Kim, Tae Un; Kim, Chang Won; Jeong, Yeon Ju; Jeong, Dong Wook; Lim, Soo Jin

    2013-06-01

    To compare vascular enhancement, image quality, and radiation dose of 128-slice dual-source CT venography (CTV) between an imaging setting of 120 kVp with low pitch, and a setting of 100 kVp combined with high pitch and automatic tube current modulation. A total of 100 patients with suspected deep vein thrombosis and varicose veins were divided into two groups: Group 1 [50 patients, 120 kVp, low pitch (0.6), and fixed 120 mA) and Group 2 (50 patients, 100 kVp, high pitch (3.0), and automatic tube current modulation]. Two radiologists, who were blinded to the image protocol, assessed vascular enhancement and image noise in the inferior vena cava (IVC), femoral vein, and popliteal vein. They also assigned an image quality score independently using a 5-point visual scale. Effective dose was estimated using the dose-length product (DLP). Group demographics, radiation dose, vascular enhancement, image noise, and image quality in the two groups were analyzed. Mean vascular enhancement of the IVC, femoral vein, and popliteal vein was significantly higher in group 2 than in group 1, and images in group 2 had significantly higher image noise. However, there were no significant differences in subjective image quality score of the IVC, femoral vein, and popliteal vein. The mean DLP in group 2 (402.10 ± 94.29 mGy cm) was significantly lower than that in group 1 (973.36 ± 63.20 mGy cm) (P < 0.001). Lower extremity CTV using 100 kVp, high pitch (3.0), and automatic tube current modulation improved vascular enhancement with acceptable image quality and low radiation dose.

  4. 46 CFR 129.326 - Dual-voltage generators.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Dual-voltage generators. 129.326 Section 129.326... INSTALLATIONS Power Sources and Distribution Systems § 129.326 Dual-voltage generators. If a dual-voltage generator is installed on an OSV— (a) The neutral of the dual-voltage system must be solidly grounded at...

  5. 46 CFR 120.324 - Dual voltage generators.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Dual voltage generators. 120.324 Section 120.324... INSTALLATION Power Sources and Distribution Systems § 120.324 Dual voltage generators. (a) A dual voltage generator installed on a vessel shall be of the grounded type, where: (1) The neutral of a dual...

  6. 46 CFR 129.326 - Dual-voltage generators.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Dual-voltage generators. 129.326 Section 129.326... INSTALLATIONS Power Sources and Distribution Systems § 129.326 Dual-voltage generators. If a dual-voltage generator is installed on an OSV— (a) The neutral of the dual-voltage system must be solidly grounded at...

  7. 46 CFR 120.324 - Dual voltage generators.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Dual voltage generators. 120.324 Section 120.324... INSTALLATION Power Sources and Distribution Systems § 120.324 Dual voltage generators. (a) A dual voltage generator installed on a vessel shall be of the grounded type, where: (1) The neutral of a dual...

  8. 46 CFR 129.326 - Dual-voltage generators.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Dual-voltage generators. 129.326 Section 129.326... INSTALLATIONS Power Sources and Distribution Systems § 129.326 Dual-voltage generators. If a dual-voltage generator is installed on an OSV— (a) The neutral of the dual-voltage system must be solidly grounded at...

  9. 46 CFR 120.324 - Dual voltage generators.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Dual voltage generators. 120.324 Section 120.324... INSTALLATION Power Sources and Distribution Systems § 120.324 Dual voltage generators. (a) A dual voltage generator installed on a vessel shall be of the grounded type, where: (1) The neutral of a dual...

  10. 46 CFR 120.324 - Dual voltage generators.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Dual voltage generators. 120.324 Section 120.324... INSTALLATION Power Sources and Distribution Systems § 120.324 Dual voltage generators. (a) A dual voltage generator installed on a vessel shall be of the grounded type, where: (1) The neutral of a dual...

  11. 46 CFR 120.324 - Dual voltage generators.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Dual voltage generators. 120.324 Section 120.324... INSTALLATION Power Sources and Distribution Systems § 120.324 Dual voltage generators. (a) A dual voltage generator installed on a vessel shall be of the grounded type, where: (1) The neutral of a dual...

  12. 46 CFR 129.326 - Dual-voltage generators.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Dual-voltage generators. 129.326 Section 129.326... INSTALLATIONS Power Sources and Distribution Systems § 129.326 Dual-voltage generators. If a dual-voltage generator is installed on an OSV— (a) The neutral of the dual-voltage system must be solidly grounded at...

  13. 46 CFR 129.326 - Dual-voltage generators.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Dual-voltage generators. 129.326 Section 129.326... INSTALLATIONS Power Sources and Distribution Systems § 129.326 Dual-voltage generators. If a dual-voltage generator is installed on an OSV— (a) The neutral of the dual-voltage system must be solidly grounded at...

  14. Application of the Low-dose One-stop-shop Cardiac CT Protocol with Third-generation Dual-source CT.

    PubMed

    Lin, Lu; Wang, Yining; Yi, Yan; Cao, Jian; Kong, Lingyan; Qian, Hao; Zhang, Hongzhi; Wu, Wei; Wang, Yun; Jin, Zhengyu

    2017-02-20

    Objective To evaluate the feasibility of a low-dose one-stop-shop cardiac CT imaging protocol with third-generation dual-source CT (DSCT). Methods Totally 23 coronary artery disease (CAD) patients were prospectively enrolled between March to September in 2016. All patients underwent an ATP stress dynamic myocardial perfusion imaging (MPI) (data acquired prospectively ECG-triggered during end systole by table shuttle mode in 32 seconds) at 70 kV combined with prospectively ECG-triggered high-pitch coronary artery angiography (CCTA) on a third-generation DSCT system. Myocardial blood flow (MBF) was quantified and compared between perfusion normal and abnormal myocardial segments based on AHA-17-segment model. CCTA images were evaluated qualitatively based on SCCT-18-segment model and the effective dose(ED) was calculated. In patients with subsequent catheter coronary angiography (CCA) as reference,the diagnosis performance of MPI (for per-vessel ≥50% and ≥70% stenosis) and CCTA (for≥50% stenosis) were assessed. Results Of 23 patients who had completed the examination of ATP stress MPI plus CCTA,12 patients received follow-up CCA. At ATP stress MPI,77 segments (19.7%) in 13 patients (56.5%) had perfusion abnormalities. The MBF values of hypo-perfused myocardial segments decreased significantly compared with normal segments [(93±22)ml/(100 ml·min) vs. (147±27)ml/(100 ml·min);t=15.978,P=0.000]. At CCTA,93.9% (308/328) of the coronary segments had diagnostic image quality. With CCA as the reference standard,the per-vessel and per-segment sensitivity,specificity,and accuracy of CCTA for stenosis≥50% were 94.1%,93.5%,and 93.7% and 90.9%,97.8%,and 96.8%,and the per-vessel sensitivity,specificity and accuracy of ATP stress MPI for stenosis≥50% and ≥70% were 68.7%,100%,and 89.5% and 91.7%,100%,and 97.9%. The total ED of MPI and CCTA was (3.9±1.3) mSv [MPI:(3.5±1.2) mSv,CCTA:(0.3±0.1) mSv]. Conclusion The third-generation DSCT stress dynamic MPI at 70 k

  15. Identification of dissolved sulfate sources and the role of sulfuric acid in carbonate weathering using dual-isotopic data from the Jialing River, Southwest China

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Dong; Liu, Cong-Qiang; Liu, Xiao-Long; Bao, Li-Ran

    2011-08-01

    Rock weathering by carbonic acid has played a substantial role in both the global carbon cycle and related climate change. Carbonic acid as the major weathering agent has been accepted, whereas the importance of other acid (sulfuric, nitric or organic acids) as an agent is gradually recognized. Here, we examine sulfate dual-isotopic evidence ( δ34S and δ18O) and water chemistry from the Jialing River (Sichuan Basin, Southwest China) to identify dissolved sulfate sources and the role of sulfuric acid in carbonate weathering. A survey was carried out at 29 sites where surface water was sampled during the rainy (July, 2008) and dry (February, 2009) seasons in the Jialing River. The chemical composition of river water was characterized by a dominance of Ca 2+, Mg 2+ and HCO3-, and SO42-, which accounted for more than 90% of the total ion concentrations. Water chemistry varied greatly in time and space, particularly for Na +, Cl -, and SO42-. This variation was a result of anthropogenic influences, such as acid deposition and domestic sewage inputs. Co-variation of the equivalent ratios of [Ca 2+ + Mg 2+] and [ SO42- + HCO3-] indicate that it required significant additional SO42- to achieve ionic balance, which implied that sulfuric acid might play a relatively important role in carbonate weathering of this river basin. Water samples from the Jialing River were significantly rich in SO42-, and increased almost two times from 274 μM in the period of 1958-1990 to 499 μM in this study. The use of co-variations of δ34Svs. δ18O and of δ18Ovs. δ18OO allowed us to demonstrate that most of the sulfate in the waters of the Jialing River was derived from sulfide oxidation and atmospheric inputs by high sulfur-content coal combustion while the contribution of sulfate from domestic and industrial wastewater could be important in the dry season. Thus, the contribution of sulfuric acid, produced by such sulfide oxidation and the oxidation of atmospheric SO 2 emitted from coal

  16. Using nitrate dual isotopic composition (δ15N and δ18O) as a tool for exploring sources and cycling of nitrate in an estuarine system: Elkhorn Slough, California

    NASA Astrophysics Data System (ADS)

    Wankel, Scott D.; Kendall, Carol; Paytan, Adina

    2009-03-01

    Nitrate (NO3-) concentrations and dual isotopic composition (δ15N and δ18O) were measured during various seasons and tidal conditions in Elkhorn Slough to evaluate mixing of sources of NO3- within this California estuary. We found the isotopic composition of NO3- was influenced most heavily by mixing of two primary sources with unique isotopic signatures, a marine (Monterey Bay) and terrestrial agricultural runoff source (Old Salinas River). However, our attempt to use a simple two end-member mixing model to calculate the relative contribution of these two NO3- sources to the Slough was complicated by periods of nonconservative behavior and/or the presence of additional sources, particularly during the dry season when NO3- concentrations were low. Although multiple linear regression generally yielded good fits to the observed data, deviations from conservative mixing were still evident. After consideration of potential alternative sources, we concluded that deviations from two end-member mixing were most likely derived from interactions with marsh sediments in regions of the Slough where high rates of NO3- uptake and nitrification result in NO3- with low δ15N and high δ18O values. A simple steady state dual isotope model is used to illustrate the impact of cycling processes in an estuarine setting which may play a primary role in controlling NO3- isotopic composition when and where cycling rates and water residence times are high. This work expands our understanding of nitrogen and oxygen isotopes as biogeochemical tools for investigating NO3- sources and cycling in estuaries, emphasizing the role that cycling processes may play in altering isotopic composition.

  17. Neural Correlates of Confidence during Item Recognition and Source Memory Retrieval: Evidence for Both Dual-Process and Strength Memory Theories

    ERIC Educational Resources Information Center

    Hayes, Scott M.; Buchler, Norbou; Stokes, Jared; Kragel, James; Cabeza, Roberto

    2011-01-01

    Although the medial-temporal lobes (MTL), PFC, and parietal cortex are considered primary nodes in the episodic memory network, there is much debate regarding the contributions of MTL, PFC, and parietal subregions to recollection versus familiarity (dual-process theory) and the feasibility of accounts on the basis of a single memory strength…

  18. System Design as a Three-Phase Dual-Loop (TPDL) Process: Types of Knowledge-Applied Sources of Feedback, and Student Development as Independent Learners

    ERIC Educational Resources Information Center

    Barak, Moshe

    2010-01-01

    This study aimed at exploring how high school students deal with designing an information system, for example, for a small business or a medical clinic, the extent to which students develop as independent learners while working on their projects, and the factors that help or hinder fostering students' design skills. The three-phase dual-loop…

  19. Mid-infrared difference-frequency generation source pumped by 1.1-1.5 micrometer dual-wavelength fiber amplifier for trace-gas detection

    NASA Technical Reports Server (NTRS)

    Goldberg, L.; Koplow, J.; Lancaster, D. G.; Curl, R. F.; Tittel, F. K.

    1998-01-01

    Continuous-wave mid-infrared radiation near 3.5 micrometers is generated by difference-frequency mixing of the output of a compact 1.1-1.5 micrometer dual-wavelength fiber amplifier in periodically poled LiNbO3. The diode side-pumped amplifier is constructed with double-cladding Yb-doped fiber followed by single-mode Er/Yb codoped fiber. Output powers of as much as 11 microW at 3.4 micrometers are obtained, and spectroscopic detection of CH4 and H2CO is demonstrated. c 1998 Optical Society of America.

  20. 46 CFR 183.324 - Dual voltage generators.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Dual voltage generators. 183.324 Section 183.324... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.324 Dual voltage generators. (a) A dual voltage generator installed on a vessel shall be of the grounded type, where: (1)...

  1. 46 CFR 183.324 - Dual voltage generators.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Dual voltage generators. 183.324 Section 183.324... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.324 Dual voltage generators. (a) A dual voltage generator installed on a vessel shall be of the grounded type, where: (1)...

  2. 46 CFR 183.324 - Dual voltage generators.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Dual voltage generators. 183.324 Section 183.324... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.324 Dual voltage generators. (a) A dual voltage generator installed on a vessel shall be of the grounded type, where: (1)...

  3. 46 CFR 183.324 - Dual voltage generators.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Dual voltage generators. 183.324 Section 183.324... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.324 Dual voltage generators. (a) A dual voltage generator installed on a vessel shall be of the grounded type, where: (1)...

  4. 46 CFR 183.324 - Dual voltage generators.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Dual voltage generators. 183.324 Section 183.324... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.324 Dual voltage generators. (a) A dual voltage generator installed on a vessel shall be of the grounded type, where: (1)...

  5. Fringe Formation in Dual-Hologram Interferometry

    NASA Technical Reports Server (NTRS)

    Burner, A. W.

    1989-01-01

    A first order geometrical optics treatment of holograms combined with the generation of interference fringes by two point sources is used to describe reference fringe formation in non-diffuse dual-hologram interferometry.

  6. Detection of ischaemic myocardial lesions with coronary CT angiography and adenosine-stress dynamic perfusion imaging using a 128-slice dual-source CT: diagnostic performance in comparison with cardiac MRI

    PubMed Central

    Kim, S M; Choi, J-H; Chang, S-A

    2013-01-01

    Objective: We assessed the diagnostic performance of adenosine-stress dynamic CT perfusion (ASDCTP) imaging and coronary CT angiography (CCTA) for the detection of ischaemic myocardial lesions using 128-slice dual-source CT compared with that of 1.5 T cardiac MRI. Methods: This prospective study included 33 patients (61±8 years, 82% male) with suspected coronary artery diseases who underwent ASDCTP imaging and adenosine-stress cardiac MRI. Two investigators independently evaluated ASDCTP images in correlation with significant coronary stenosis on CCTA using two different thresholds of 50% and 70% diameter stenosis. Hypoattenuated myocardial lesions on ASDCTP associated with significant coronary stenoses on CCTA were regarded as true perfusion defects. All estimates of diagnostic performance were calculated and compared with those of cardiac MRI. Results: With use of a threshold of 50% diameter stenosis on CCTA, the diagnostic estimates per-myocardial segment were as follows: sensitivity, 81% [95% confidence interval (CI): 70–92%]; specificity, 94% (95% CI: 92–96%); and accuracy 93% (95% CI: 91–95%). With use of a threshold of 70%, the diagnostic estimates were as follows: sensitivity, 48% (95% CI: 34–62%); specificity, 99% (95% CI: 98–100%); and accuracy, 94% (95% CI: 92–96%). Conclusion: Dynamic CTP using 128-slice dual-source CT enables the assessment of the physiological significance of coronary artery lesions with high diagnostic accuracy in patients with clinically suspected coronary artery disease. Advances in knowledge: Combined CCTA and ASDCTP yielded high accuracy in the detection of perfusion defects regardless of the threshold of significant coronary stenosis. PMID:24096592

  7. Effect of the working gas of the ion-assisted source on the optical and mechanical properties of SiO2 films deposited by dual ion beam sputtering with Si and SiO2 as the starting materials.

    PubMed

    Wu, Jean-Yee; Lee, Cheng-Chung

    2006-05-20

    Silicon and fused-silica targets are used as the starting materials for depositing silicon oxide (SiO2) films. The SiO2 films are prepared by a dual ion beam sputtering deposition system with a main ion source and an ion-assisted source with different working gases. The films deposited are then examined and compared by using a visible spectrophotometer, a Fourier-transform IR spectrophotometer, an atomic force microscope, and contact angle instruments. A Twyman-Green interferometer is employed to study the film stress by phase-shift interferometry. All the SiO2 films show excellent optical properties with extra-low extinction coefficients (below 2x10(-5)) and have no water absorption. When the working gas is O2 for the ion-assisted source, the deposited SiO2 films show good properties in terms of stress and roughness and with a good molecular bonding structure order for both targets. However, SiO2 films deposited from the fused-silica target had a larger contact angle, while those deposited from the silicon target had 2.5 times the deposition rate.

  8. Using dual isotopes to identify sources and transformations of nitrogen in water catchments with different land uses, Loess Plateau of China.

    PubMed

    Xing, Meng; Liu, Weiguo

    2016-01-01

    Nitrogen pollution in rivers is a research hotspot in the field of biogeochemistry. However, the types and sources of pollution have historically been poorly understood in the water catchments of the Loess Plateau in China. In this study, we have chosen the main waterway and four lesser branches of the Jinghe River that vary by land use. We investigated the concentrations and isotopic signatures of nitrogen in river water. Our results revealed that nitrate was the dominant nitrogen type in river catchments of the Loess Plateau. The δ(15)N and δ(18)O values showed that NO3 (-) ions in the studied river samples were derived from precipitation, manure, sewage, soil organic nitrogen, and synthetic NO3 (-) fertilizer. The δ(18)O-NO3 (-) values during July 2012 (mean ± SD = +18.1 ± 1.5‰) were higher than those during the September 2013 (mean ± SD = +7.8 ± 3.7‰), which indicated that mixing with atmospheric NO3 (-) resulted in the high δ(18)O values during July 2012. It appears that no intense nitrification and denitrification occurred in all five rivers according to the isotopic and chemical data. A Bayesian model was used to determine the contributions of four NO3 (-) sources to all five rivers. Results showed that source contributions differ significantly between July and September, and the four potential NO3 (-) sources also showed high variability between the different land use areas.

  9. Amino acids as a nitrogen source in temperate upland grasslands: the use of dual labelled ((13)C, (15)N) glycine to test for direct uptake by dominant grasses.

    PubMed

    Streeter, T C; Bol, R; Bardgett, R D

    2000-01-01

    It is becoming increasingly apparent that soil amino acids are a principal source of nitrogen (N) for certain plants, and especially those of N-limited environments. This study of temperate upland grasslands used glycine-2-(13)C-(15)N and ((15)NH4)(2)SO(4) labelling techniques to test the hypothesis that plant species which dominate 'unimproved' semi-natural grasslands (Festuca-Agrostis-Galium) are able to utilise amino acid N for growth, whereas those plants which dominate 'improved' grasslands (Lolium-Cynosurus), that receive regular applications of inorganic fertiliser, use inorganic N forms as their main N source. Data from field experiments confirmed that 'free' amino acids were more abundant in 'unimproved' than 'improved' grassland and that glycine was the dominant amino acid type (up to 42% of total). Secondly, the injection of representative amounts of glycine-2-(13)C-(15)N (4.76 and 42.86 mM) into intact soil cores from the two grassland types provided evidence of direct uptake of glycine by plants, with both (15)N and (13)C being detected in plant material of both grasslands. Finally, a microcosm experiment demonstrated no preferential uptake of amino acid N by the grasses which dominate the grassland types, namely Holcus lanatus, Festuca rubra, Agrostis capillaris from the 'unimproved' grassland, and Lolium perenne from the 'improved' grassland. Again, both (13)C and (15)N were detected in all grass species suggesting uptake of intact glycine by these plants.

  10. Dual surface interferometer

    DOEpatents

    Pardue, R.M.; Williams, R.R.

    1980-09-12

    A double-pass interferometer is provided which allows direct measurement of relative displacement between opposed surfaces. A conventional plane mirror interferometer may be modified by replacing the beam-measuring path cube-corner reflector with an additional quarterwave plate. The beam path is altered to extend to an opposed plane mirrored surface and the reflected beam is placed in interference with a retained reference beam split from dual-beam source and retroreflected by a reference cube-corner reflector mounted stationary with the interferometer housing. This permits direct measurement of opposed mirror surfaces by laser interferometry while doubling the resolution as with a conventional double-pass plane mirror laser interferometer system.

  11. Dual surface interferometer

    DOEpatents

    Pardue, Robert M.; Williams, Richard R.

    1982-01-01

    A double-pass interferometer is provided which allows direct measurement of relative displacement between opposed surfaces. A conventional plane mirror interferometer may be modified by replacing the beam-measuring path cube-corner reflector with an additional quarter-wave plate. The beam path is altered to extend to an opposed plane mirrored surface and the reflected beam is placed in interference with a retained reference beam split from dual-beam source and retroreflected by a reference cube-corner reflector mounted stationary with the interferometer housing. This permits direct measurement of opposed mirror surfaces by laser interferometry while doubling the resolution as with a conventional double-pass plane mirror laser interferometer system.

  12. Fringe formation in dual-hologram interferometry

    NASA Astrophysics Data System (ADS)

    Burner, A. W.

    Reference-fringe formation in nondiffuse dual-hologram interferometry is described by combining a first-order geometrical hologram treatment with interference fringes generated by two point sources. The first-order imaging relationships can be used to describe reference-fringe patterns for the geometry of the dual-hologram interferometry. The process can be completed without adjusting the two holograms when the reconstructing wavelength is less than the exposing wavelength, and the process is found to facilitate basic intereferometer adjustments.

  13. Identification of groundwater contamination sources of nitrate and sulfate in shallow alluvial aquifers using a dual-isotope approach in an agricultural area

    NASA Astrophysics Data System (ADS)

    Kaown, D.; Koh, D.; Mayer, B.; Hyun, Y.; Bae, G.; Lee, K.

    2007-12-01

    The elevated level of nitrate in groundwater is a serious problem in Korean agricultural areas. Yupori, a small agricultural area in Chuncheon (Korea), shows a rising level of NO3-N and displays multiple NO3-N sources from non-point and point sources in shallow aquifer groundwater. Numerous vegetable fields are located in the western part of the study area and fruit orchards dominate the landscape with only few vegetable fields in the eastern part of the study area. The source identification of groundwater contamination from overburden agricultural area was undertaken by analyzing hydrochemical data and stable isotopic compositions of dissolved nitrate and sulfate (¥ä15N-NO3-, ¥ä18O-NO3-, ¥ä34S-SO42-, and ¥ä18O-SO42-). The measurements of ¥ä15N- NO3- are in the range of 7.1 to 14.4¢¶ and the values of ¥ä18O-NO3- are in the range of -1.8 to 6.5¢¶. High ¥ä15N-NO3- values shown at low concentrations of nitrate in the eastern Yupori are characteristics of manure- derived nitrate and organic soil. The values of ¥ä34S-SO4-2 ranged from 2.9 to 9.9¢¶ and ¥ä18O-SO42- ranged from 2.5 to 4.7¢¶. At high concentrations of SO42- in the western Yupori, the value of ¥ä34S-SO42- are low around 3-4¢¶. The value of ¥ä34S-SO42- increased with decreasing SO42- concentration in the eastern Yupori. Groundwater quality and stable isotopic compositions of dissolved nitrate and sulfate seem to be significantly affected by agricultural land use pattern of the study site.

  14. Dual sources of water overprinting on the low zircon δ18O metamorphic country rocks: Disequilibrium constrained through inverse modelling of partial reequilibration

    PubMed Central

    Wei, Chun-Sheng; Zhao, Zi-Fu

    2017-01-01

    Since water is only composed of oxygen and hydrogen, δ18O and δ2H values are thus utilized to trace the origin of water(s) and quantify the water-rock interactions. While Triassic high pressure (HP) and ultrahigh pressure (UHP) metamorphic rocks across the Dabie-Sulu orogen in central-eastern China have been well documented, postcollisional magmatism driven hydrothermal systems are little known. Here we show that two sources of externally derived water interactions were revealed by oxygen isotopes for the gneissic country rocks intruded by the early Cretaceous postcollisional granitoids. Inverse modellings indicate that the degree of disequilibrium (doD) of meteoric water interactions was more evident than that of magmatic one (−65 ± 1o vs. −20 ± 2°); the partial reequilibration between quartz and alkali feldspar oxygen isotopes with magmatic water was achieved at 340 °C with a water/rock (W/R) ratio of about 1.2 for an open-hydrothermal system; two-stage meteoric water interactions were unraveled with reequilibration temperatures less than 300 °C and W/R ratios around 0.4. The lifetime of fossil magmatic hydrothermal system overprinted on the low zircon δ18O orthogneissic country rocks was estimated to maintain up to 50 thousand years (Kyr) through oxygen exchange modellings. Four-stage isotopic evolutions were proposed for the magmatic water interacted gneiss. PMID:28091552

  15. Dual sources of water overprinting on the low zircon δ18O metamorphic country rocks: Disequilibrium constrained through inverse modelling of partial reequilibration

    NASA Astrophysics Data System (ADS)

    Wei, Chun-Sheng; Zhao, Zi-Fu

    2017-01-01

    Since water is only composed of oxygen and hydrogen, δ18O and δ2H values are thus utilized to trace the origin of water(s) and quantify the water-rock interactions. While Triassic high pressure (HP) and ultrahigh pressure (UHP) metamorphic rocks across the Dabie-Sulu orogen in central-eastern China have been well documented, postcollisional magmatism driven hydrothermal systems are little known. Here we show that two sources of externally derived water interactions were revealed by oxygen isotopes for the gneissic country rocks intruded by the early Cretaceous postcollisional granitoids. Inverse modellings indicate that the degree of disequilibrium (doD) of meteoric water interactions was more evident than that of magmatic one (‑65 ± 1o vs. ‑20 ± 2°) the partial reequilibration between quartz and alkali feldspar oxygen isotopes with magmatic water was achieved at 340 °C with a water/rock (W/R) ratio of about 1.2 for an open-hydrothermal system; two-stage meteoric water interactions were unraveled with reequilibration temperatures less than 300 °C and W/R ratios around 0.4. The lifetime of fossil magmatic hydrothermal system overprinted on the low zircon δ18O orthogneissic country rocks was estimated to maintain up to 50 thousand years (Kyr) through oxygen exchange modellings. Four-stage isotopic evolutions were proposed for the magmatic water interacted gneiss.

  16. Dual sources of water overprinting on the low zircon δ(18)O metamorphic country rocks: Disequilibrium constrained through inverse modelling of partial reequilibration.

    PubMed

    Wei, Chun-Sheng; Zhao, Zi-Fu

    2017-01-16

    Since water is only composed of oxygen and hydrogen, δ(18)O and δ(2)H values are thus utilized to trace the origin of water(s) and quantify the water-rock interactions. While Triassic high pressure (HP) and ultrahigh pressure (UHP) metamorphic rocks across the Dabie-Sulu orogen in central-eastern China have been well documented, postcollisional magmatism driven hydrothermal systems are little known. Here we show that two sources of externally derived water interactions were revealed by oxygen isotopes for the gneissic country rocks intruded by the early Cretaceous postcollisional granitoids. Inverse modellings indicate that the degree of disequilibrium (doD) of meteoric water interactions was more evident than that of magmatic one (-65 ± 1(o) vs. -20 ± 2°); the partial reequilibration between quartz and alkali feldspar oxygen isotopes with magmatic water was achieved at 340 °C with a water/rock (W/R) ratio of about 1.2 for an open-hydrothermal system; two-stage meteoric water interactions were unraveled with reequilibration temperatures less than 300 °C and W/R ratios around 0.4. The lifetime of fossil magmatic hydrothermal system overprinted on the low zircon δ(18)O orthogneissic country rocks was estimated to maintain up to 50 thousand years (Kyr) through oxygen exchange modellings. Four-stage isotopic evolutions were proposed for the magmatic water interacted gneiss.

  17. Effect of nitrogen flow rate on structural, morphological and optical properties of In-rich InxAl1-xN thin films grown by plasma-assisted dual source reactive evaporation

    NASA Astrophysics Data System (ADS)

    Alizadeh, M.; Ganesh, V.; Goh, B. T.; Dee, C. F.; Mohmad, A. R.; Rahman, S. A.

    2016-08-01

    In-rich InxAl1-xN thin films were deposited on quartz substrate at various nitrogen flow rates by plasma-assisted dual source reactive evaporation technique. The elemental composition, surface morphology, structural and optical properties of the films were investigated by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Raman spectroscopy, X-ray diffraction (XRD), UV-vis spectrophotometer and photoluminescence (PL) measurements. XPS results revealed that the indium composition (x) of the InxAl1-xN films increases from 0.90 to 0.97 as the nitrogen flow rate is increased from 40 to 100 sccm, respectively. FESEM images of the surface and cross-sectional microstructure of the InxAl1-xN films showed that by increasing the N2 flow rate, the grown particles are highly agglomerated. Raman and XRD results indicated that by increasing nitrogen flow rate the In-rich InxAl1-xN films tend to turn into amorphous state. It was found that band gap energy of the films are in the range of 0.90-1.17 eV which is desirable for the application of full spectra solar cells.

  18. Dual Wavelength Lasers

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.

    2010-01-01

    Dual wavelength lasers are discussed, covering fundamental aspects on the spectroscopy and laser dynamics of these systems. Results on Tm:Ho:Er:YAG dual wavelength laser action (Ho at 2.1 m and Er at 2.9 m) as well as Nd:YAG (1.06 and 1.3 m) are presented as examples of such dual wavelength systems. Dual wavelength lasers are not common, but there are criteria that govern their behavior. Based on experimental studies demonstrating simultaneous dual wavelength lasing, some general conclusions regarding the successful operation of multi-wavelength lasers can be made.

  19. Dual 10Be isotope systems constrain the source of sediment and rate of erosion for the tropical Barron River catchment, Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Nichols, K. K.; Bierman, P. R.; Reusser, L. J.; Portenga, E.; Matmon, A.; Rood, D. H.

    2010-12-01

    In order to understand source of sediment and rate of erosion for Barron River catchment, which heads on the Atherton Tablelands of northeast Australia, crosses the northern Queensland escarpment and drains into the Coral Sea, we collected fluvial sediment and measured both in situ and meteoric 10Be contents on the medium sand fraction. We collected fourteen samples from rivers and streams including large regional drainages and small tributaries. The upland basins are characterized by lower relief and less precipitation than the steeper and wetter escarpment basins. One sample is quartz sand from the Coral Sea beach at Yorkey's Knob, below the escarpment. Sand from the Barron River upstream of the escarpment integrates the upland basins and has an in situ 10Be concentration of 2.31±0.84 x105atoms/g and an erosion rate of 17.2 m/My (calculated using the CRONOS on-line calculator). This is similar to a major upland tributary (2.51±0.40 x105 atoms/g; 15.2 m/My) and two smaller upstream tributaries (20.5 m/My and 21.4 m/My). Escarpment streams have less in situ 10Be in their sediment (mean = 1.64±0.55 x 105 atoms/g, n=8) and higher basin area-weighted erosion rates (37.2 m/My). Based on the in situ measurements, the uplands are eroding at approximately half the rate of the escarpment basins. The beach sand has an in situ 10Be concentration (2.75±0.19 x 105 atoms/g) similar to the upland sediment suggesting that the source of beach sand is the larger but more slowly eroding Tablelands. In contrast, the meteoric 10Be concentrations of Barron River sand-sized sediment collected above the escarpment is ~4 fold lower (2.55x107 atoms/g) than the average meteoric 10Be concentration of the 8 escarpment samples (9.94±4.49 x107 atoms/g). This discrepancy cannot be explained by differences in annual average precipitation which ranges only from 1.9 to 2.3 m/yr but likely results from the deep mobility of meteoric 10Be in oxic Tableland soils. Considering meteoric 10Be as a

  20. Mental Health and Psychological Functioning of Dual-Career Families.

    ERIC Educational Resources Information Center

    Gilbert, Lucia Albino; Rachlin, Vicki

    1987-01-01

    Identifies key issues in the psychosocial development of women and men that are important to understanding dual-career marriages. Describes life as a dual career family considering rewards, sources of stress, and factors that promote effective coping. Addresses pertinent metaissues--concepts of equity and the nature of society. Offers…

  1. TH-C-18A-12: Evaluation of the Impact of Body Size and Tube Output Limits in the Optimization of Fast Scanning with High-Pitch Dual Source CT

    SciTech Connect

    Ramirez Giraldo, J; Mileto, A.; Hurwitz, L.; Marin, D.

    2014-06-15

    Purpose: To evaluate the impact of body size and tube power limits in the optimization of fast scanning with high-pitch dual source CT (DSCT). Methods: A previously validated MERCURY phantom, made of polyethylene, with circular cross-section of diameters 16, 23, 30 and 37cm, and connected through tapered sections, was scanned using a second generation DSCT system. The DSCT operates with two independently controlled x-ray tube generators offering up to 200 kW power reserve (100 kW per tube). The entire length of the phantom (42cm) was scanned with two protocols using: A)Standard single-source CT (SSCT) protocol with pitch of 0.8, and B) DSCT protocol with high-pitch values ranging from 1.6 to 3.2 (0.2 steps). All scans used 120 kVp with 150 quality reference mAs using automatic exposure control. Scanner radiation output (CTDIvol) and effective mAs values were extracted retrospectively from DICOM files for each slice. Image noise was recorded. All variables were assessed relative to phantom diameter. Results: With standard-pitch SSCT, the scanner radiation output (and tube-current) were progressively adapted with increasing size, from 6 mGy (120 mAs) up to 15 mGy (270 mAs) from the thinnest (16cm) to the thickest diameter (37 cm), respectively. By comparison, using high-pitch (3.2), the scanner output was bounded at about 8 mGy (140 mAs), independent of phantom diameter. Although relative to standard-pitch, the high-pitch led to lower radiation output for the same scan, the image noise was higher, particularly for larger diameters. To match the radiation output adaptation of standard-pitch, a high-pitch mode of 1.6 was needed, with the advantage of scanning twice as fast. Conclusion: To maximize the benefits of fast scanning with high-pitch DSCT, the body size and tube power limits of the system need to be considered such that a good balance between speed of acquisition and image quality are warranted. JCRG is an employee of Siemens Medical Solutions USA Inc.

  2. Dual Enrollment Academy Programs

    ERIC Educational Resources Information Center

    Gonzalez, Nicolas; Chavez, Guadalupe

    2009-01-01

    Dual Enrollment Engineering (DEEA) and Medical Science (DEMSA) Academies are two-year dual enrollment programs for high school students. Students explore engineering and medical careers through college coursework. Students prepare for higher education in engineering and medical fields while completing associate degrees in biology or engineering…

  3. A model for quantitative correction of coronary calcium scores on multidetector, dual source, and electron beam computed tomography for influences of linear motion, calcification density, and temporal resolution: A cardiac phantom study

    SciTech Connect

    Greuter, M. J. W.; Groen, J. M.; Nicolai, L. J.; Dijkstra, H.; Oudkerk, M.

    2009-11-15

    Purpose: The objective of this study is to quantify the influence of linear motion, calcification density, and temporal resolution on coronary calcium determination using multidetector computed tomography (MDCT), dual source CT (DSCT), and electron beam tomography (EBT) and to find a quantitative method which corrects for the influences of these parameters using a linear moving cardiac phantom. Methods: On a robotic arm with artificial arteries with four calcifications of increasing density, a linear movement was applied between 0 and 120 mm/s (step of 10 mm/s). The phantom was scanned five times on 64-slice MDCT, DSCT, and EBT using a standard acquisition protocol. The average Agatston, volume, and mass scores were determined for each velocity, calcification, and scanner. Susceptibility to motion was quantified using a cardiac motion susceptibility (CMS) index. Resemblance to EBT and physical volume and mass was quantified using a {Delta} index. Results: Increasing motion artifacts were observed at increasing velocities on all scanners, with increasing severity from EBT to DSCT to 64-slice MDCT. The calcium score showed a linear dependency on motion from which a correction factor could be derived. This correction factor showed a linear dependency on the mean calcification density with a good fit for all three scoring methods and all three scanners (0.73{<=}R{sup 2}{<=}0.95). The slope and offset of this correction factor showed a linear dependency on temporal resolution with a good fit for all three scoring methods and all three scanners (0.83{<=}R{sup 2}{<=}0.98). CMS was minimal for EBT and increasing values were observed for DSCT and highest values for 64-slice MDCT. CMS was minimal for mass score and increasing values were observed for volume score and highest values for Agatston score. For all densities and scoring methods DSCT showed on average the closest resemblance to EBT calcium scores. When using the correction factor, CMS index decreased on average by

  4. Dual Credit/Dual Enrollment and Data Driven Policy Implementation

    ERIC Educational Resources Information Center

    Lichtenberger, Eric; Witt, M. Allison; Blankenberger, Bob; Franklin, Doug

    2014-01-01

    The use of dual credit has been expanding rapidly. Dual credit is a college course taken by a high school student for which both college and high school credit is given. Previous studies provided limited quantitative evidence that dual credit/dual enrollment is directly connected to positive student outcomes. In this study, predictive statistics…

  5. Bifocal dual reflector antenna

    NASA Technical Reports Server (NTRS)

    Rao, B. L. J.

    1973-01-01

    A bifocal dual reflector antenna is similar to and has better scan capability than classical cassegrain reflector antenna. The method used in determining the reflector surfaces is a modification of a design method for the dielectric bifocal lens. The three dimensional dual reflector is obtained by first designing an exact (in geometrical optics sense) two-point corrected two dimensional reflector and then rotating it around its axis of symmetry. A point by point technique is used in computing the reflector surfaces. Computed radiation characteristics of the dual reflector are compared with those of a cassegrain reflector. The results confirm that the bifocal antenna has superior performance.

  6. "How to" incorporate dual-energy imaging into a high volume abdominal imaging practice.

    PubMed

    Tamm, Eric P; Le, Ott; Liu, Xinming; Layman, Rick R; Cody, Dianna D; Bhosale, Priya R

    2017-03-01

    Dual-energy CT imaging has many potential uses in abdominal imaging. It also has unique requirements for protocol creation depending on the dual-energy scanning technique that is being utilized. It also generates several new types of images which can increase the complexity of image creation and image interpretation. The purpose of this article is to review, for rapid switching and dual-source dual-energy platforms, methods for creating dual-energy protocols, different approaches for efficiently creating dual-energy images, and an approach to navigating and using dual-energy images at the reading station all using the example of a pancreatic multiphasic protocol. It will also review the three most commonly used types of dual-energy images: "workhorse" 120kVp surrogate images (including blended polychromatic and 70 keV monochromatic), high contrast images (e.g., low energy monochromatic and iodine material decomposition images), and virtual unenhanced images. Recent developments, such as the ability to create automatically on the scanner the most common dual-energy images types, namely new "Mono+" images for the DSDECT (dual-source dual-energy CT) platform will also be addressed. Finally, an approach to image interpretation using automated "hanging protocols" will also be covered. Successful dual-energy implementation in a high volume practice requires careful attention to each of these steps of scanning, image creation, and image interpretation.

  7. Dual-Mode Combustor

    NASA Technical Reports Server (NTRS)

    Trefny, Charles J (Inventor); Dippold, Vance F (Inventor)

    2013-01-01

    A new dual-mode ramjet combustor used for operation over a wide flight Mach number range is described. Subsonic combustion mode is usable to lower flight Mach numbers than current dual-mode scramjets. High speed mode is characterized by supersonic combustion in a free-jet that traverses the subsonic combustion chamber to a variable nozzle throat. Although a variable combustor exit aperture is required, the need for fuel staging to accommodate the combustion process is eliminated. Local heating from shock-boundary-layer interactions on combustor walls is also eliminated.

  8. Optical system design of dual-spectrum autocollimator

    NASA Astrophysics Data System (ADS)

    Wei, Yongjing; Wu, Yiming; Xiao, Maosen; Lu, Weiguo

    2015-10-01

    The optical system design of a new dual-spectrum autocollimator which can measure two different spatial azimuths simultaneously is proposed. According to the principle of dual-spectrum autocollimator, ZEMAX software is used to design and optimize the optical system. Since two light sources with different wavelength are used in the autocollimator, chromatic aberration is required to reduce off in the optical system design. The experimental results demonstrate that the measuring range of the dual-spectrum autocollimator is up to +/-30', the deviation is less than 1″, and the resolution can reach 0.1". The designed autocollimator can simultaneously measure two different azimuths fastly and accurately.

  9. Dual manifold heat pipe evaporator

    DOEpatents

    Adkins, D.R.; Rawlinson, K.S.

    1994-01-04

    An improved evaporator section is described for a dual manifold heat pipe. Both the upper and lower manifolds can have surfaces exposed to the heat source which evaporate the working fluid. The tubes in the tube bank between the manifolds have openings in their lower extensions into the lower manifold to provide for the transport of evaporated working fluid from the lower manifold into the tubes and from there on into the upper manifold and on to the condenser portion of the heat pipe. A wick structure lining the inner walls of the evaporator tubes extends into both the upper and lower manifolds. At least some of the tubes also have overflow tubes contained within them to carry condensed working fluid from the upper manifold to pass to the lower without spilling down the inside walls of the tubes. 1 figure.

  10. Dual manifold heat pipe evaporator

    DOEpatents

    Adkins, Douglas R.; Rawlinson, K. Scott

    1994-01-01

    An improved evaporator section for a dual manifold heat pipe. Both the upper and lower manifolds can have surfaces exposed to the heat source which evaporate the working fluid. The tubes in the tube bank between the manifolds have openings in their lower extensions into the lower manifold to provide for the transport of evaporated working fluid from the lower manifold into the tubes and from there on into the upper manifold and on to the condenser portion of the heat pipe. A wick structure lining the inner walls of the evaporator tubes extends into both the upper and lower manifolds. At least some of the tubes also have overflow tubes contained within them to carry condensed working fluid from the upper manifold to pass to the lower without spilling down the inside walls of the tubes.

  11. Dual approximations in optimal control

    NASA Technical Reports Server (NTRS)

    Hager, W. W.; Ianculescu, G. D.

    1984-01-01

    A dual approximation for the solution to an optimal control problem is analyzed. The differential equation is handled with a Lagrange multiplier while other constraints are treated explicitly. An algorithm for solving the dual problem is presented.

  12. Dual beam optical interferometer

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C. (Inventor)

    2003-01-01

    A dual beam interferometer device is disclosed that enables moving an optics module in a direction, which changes the path lengths of two beams of light. The two beams reflect off a surface of an object and generate different speckle patterns detected by an element, such as a camera. The camera detects a characteristic of the surface.

  13. Acute vertebral fracture after spinal fusion: a case report illustrating the added value of single-source dual-energy computed tomography to magnetic resonance imaging in a patient with spinal Instrumentation.

    PubMed

    Fuchs, M; Putzier, M; Pumberger, M; Hermann, K G; Diekhoff, T

    2016-09-01

    Magnetic resonance imaging (MRI) is degraded by metal-implant-induced artifacts when used for the diagnostic assessment of vertebral compression fractures in patients with instrumented spinal fusion. Dual-energy computed tomography (DECT) offers a promising supplementary imaging tool in these patients. This case report describes an 85-year-old woman who presented with a suspected acute vertebral fracture after long posterior lumbar interbody fusion. This is the first report of a vertebral fracture that showed bone marrow edema on DECT; however, edema was missed by an MRI STIR sequence owing to metal artifacts. Bone marrow assessment using DECT is less susceptible to metal artifacts than MRI, resulting in improved visualization of vertebral edema in the vicinity of fused vertebral bodies.

  14. Dual use research: investigation across multiple science disciplines.

    PubMed

    Oltmann, Shannon

    2015-04-01

    Most recent studies of dual use research have focused on the life sciences, although some researchers have suggested that dual use research occurs across many disciplines. This research is an initial investigation into the prevalence of dual use research in other scientific disciplines by surveying senior editors of scientific journals, drawn from Journal Citation Reports. The survey was emailed to 7,500 journal editors with a response rate of 10.1 %. Approximately 4.8 % of life science editors reported they had to consider whether to publish dual use research and 38.9 % said they decided to not publish the research in question. In disciplines other than the life sciences, 7.2 % of editors from other science disciplines reported that they had to consider whether to publish dual use research, and 48.4 % declined to publish it. The survey investigated relationships between dual use and the journal's source of funding and place of publication, but no relationships were found. Further research is needed to better understand the occurrence of dual use research in other science disciplines.

  15. Dual frequency comb metrology with one fiber laser

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Takeshi, Yasui; Zheng, Zheng

    2016-11-01

    Optical metrology techniques based on dual optical frequency combs have emerged as a hotly studied area targeting a wide range of applications from optical spectroscopy to microwave and terahertz frequency measurement. Generating two sets of high-quality comb lines with slightly different comb-tooth spacings with high mutual coherence and stability is the key to most of the dual-comb schemes. The complexity and costs of such laser sources and the associated control systems to lock the two frequency combs hinder the wider adoption of such techniques. Here we demonstrate a very simple and rather different approach to tackle such a challenge. By employing novel laser cavity designs in a mode-locked fiber laser, a simple fiber laser setup could emit dual-comb pulse output with high stability and good coherence between the pulse trains. Based on such lasers, comb-tooth-resolved dual-comb optical spectroscopy is demonstrated. Picometer spectral resolving capability could be realized with a fiber-optic setup and a low-cost data acquisition system and standard algorithms. Besides, the frequency of microwave signals over a large range can be determined based on a simple setup. Our results show the capability of such single-fiber-laser-based dual-comb scheme to reduce the complexity and cost of dual-comb systems with excellent quality for different dual-comb applications.

  16. GOES-R Dual Isolation

    NASA Technical Reports Server (NTRS)

    Freesland, Doug; Carter, Delano; Chapel, Jim; Clapp, Brian; Howat, John; Krimchansky, Alexander

    2015-01-01

    The Geostationary Operational Environmental Satellite-R Series (GOES-R) is the first of the next generation geostationary weather satellites, scheduled for delivery in late 2015. GOES-R represents a quantum increase in Earth and solar weather observation capabilities, with 4 times the resolution, 5 times the observation rate, and 3 times the number of spectral bands for Earth observations. With the improved resolution, comes the instrument suite's increased sensitive to disturbances over a broad spectrum 0-512 Hz. Sources of disturbance include reaction wheels, thruster firings for station keeping and momentum management, gimbal motion, and internal instrument disturbances. To minimize the impact of these disturbances, the baseline design includes an Earth Pointed Platform (EPP), a stiff optical bench to which the two nadir pointed instruments are collocated together with the Guidance Navigation & Control (GN&C) star trackers and Inertial Measurement Units (IMUs). The EPP is passively isolated from the spacecraft bus with Honeywell D-Strut isolators providing attenuation for frequencies above approximately 5 Hz in all six degrees-of-freedom. A change in Reaction Wheel Assembly (RWA) vendors occurred very late in the program. To reduce the risk of RWA disturbances impacting performance, a secondary passive isolation system manufactured by Moog CSA Engineering was incorporated under each of the six 160 Nms RWAs, tuned to provide attenuation at frequencies above approximately 50 Hz. Integrated wheel and isolator testing was performed on a Kistler table at NASA Goddard Space Flight Center. High fidelity simulations were conducted to evaluate jitter performance for four topologies: 1) hard mounted no isolation, 2) EPP isolation only, 2) RWA isolation only, and 4) dual isolation. Simulation results demonstrate excellent performance relative to the pointing stability requirements, with dual isolated Line of Sight (LOS) jitter less than 1 micron rad.

  17. Dual-Schemata Model

    NASA Astrophysics Data System (ADS)

    Taniguchi, Tadahiro; Sawaragi, Tetsuo

    In this paper, a new machine-learning method, called Dual-Schemata model, is presented. Dual-Schemata model is a kind of self-organizational machine learning methods for an autonomous robot interacting with an unknown dynamical environment. This is based on Piaget's Schema model, that is a classical psychological model to explain memory and cognitive development of human beings. Our Dual-Schemata model is developed as a computational model of Piaget's Schema model, especially focusing on sensori-motor developing period. This developmental process is characterized by a couple of two mutually-interacting dynamics; one is a dynamics formed by assimilation and accommodation, and the other dynamics is formed by equilibration and differentiation. By these dynamics schema system enables an agent to act well in a real world. This schema's differentiation process corresponds to a symbol formation process occurring within an autonomous agent when it interacts with an unknown, dynamically changing environment. Experiment results obtained from an autonomous facial robot in which our model is embedded are presented; an autonomous facial robot becomes able to chase a ball moving in various ways without any rewards nor teaching signals from outside. Moreover, emergence of concepts on the target movements within a robot is shown and discussed in terms of fuzzy logics on set-subset inclusive relationships.

  18. Dual stage check valve

    NASA Technical Reports Server (NTRS)

    Whitten, D. E. (Inventor)

    1973-01-01

    A dual stage seat valve head arrangement is described which consists of a primary sealing point located between a fixed orifice seat and a valve poppet, and a secondary sealing point between an orifice poppet and a valve poppet. Upstream of the valve orifice is a flexible, convoluted metal diaphragm attached to the orifice poppet. Downstream of the valve orifice, a finger spring exerts a force against the valve poppet, tending to keep the valve in a closed position. The series arrangement of a double seat and poppet is able to tolerate small particle contamination while minimizing chatter by controlling throttling or metering across the secondary seat, thus preserving the primary sealing surface.

  19. Dual modification of biomolecules.

    PubMed

    Maruani, Antoine; Richards, Daniel A; Chudasama, Vijay

    2016-07-14

    With the advent of novel bioorthogonal reactions and "click" chemistry, an increasing number of strategies for the single labelling of proteins and oligonucleotides have emerged. Whilst several methods exist for the site-selective introduction of a single chemical moiety, site-selective and bioorthogonal dual modification of biomolecules remains a challenge. The introduction of multiple modules enables a plethora of permutations and combinations and can generate a variety of bioconjuguates with many potential applications. From de novo approaches on oligomers to the post-translational functionalisation of proteins, this review will highlight the main strategies to dually modify biomolecules.

  20. Dual mode warhead

    SciTech Connect

    Obrsky, J.; Alexander, A.A.; Griffen, O.H.; Foster, J.S.; Shamblen, M.

    1980-12-31

    A dual mode warhead is provided for use against both soft and hard targets and capable of sensing which type of target has been struck comprising a casing made of a ductile material containing an explosive charge and a fuze assembly. The ductile warhead casing will mushroom and later split upon striking a hard target while still confining the explosive. Proper ductility and confinement are necessary for fuze sensing. The fuze assembly contains a pair of parallel firing trains, one initiated only by high and one by low impact deceleration. The firing train actuated by low impact deceleration contains a pyrotechnic delay to allow penetration of soft targets.

  1. Dual-Credit in Kentucky

    ERIC Educational Resources Information Center

    Stephenson, Lisa G.

    2013-01-01

    Credit-based transition programs provide high school students with opportunities to jump start their college education. The Kentucky Community and Technical College System (KCTCS) offers college credit through dual-credit programs. While KCTCS dual-credit offerings have been successful in helping high school students start their college education…

  2. Benefits of Dual Language Education

    ERIC Educational Resources Information Center

    Wallstrum, Kiara

    2009-01-01

    The focus of this paper examines how dual language education (DLE) programs are valuable. The literature shows that children do much more than just thrive in a dual language environment. According to research, children who are bilingual are cognitively, academically, intellectually, socially and verbally more advantaged than their monolingual…

  3. Dual redundant arm system operational quality measures and their applications - Dynamic measures

    NASA Technical Reports Server (NTRS)

    Lee, Sukhan; Kim, Sungbok

    1990-01-01

    Dual-arm dynamic operation quality measures are presented which quantify the efficiency and capability of generating Cartesian accelerations by two cooperative arms based on the analysis of dual-arm dynamic interactions. Dual-arm dynamic manipulability is defined as the efficiency of generating Cartesian accelerations under the dynamic and kinematic interactions between individual arms and an object under manipulation. The analysis of dual-arm dynamic interactions is based on the so-called Cartesian space agent model of an arm, which represents an individual arm as a force source acting upon a point mass with the effective Cartesian space arm dynamics and an environment or an object under manipulation. The Cartesian space agent model of an arm makes it possible to derive the dynamic and kinematic constraints involved in the transport, assembly and grasping modes of dual-arm cooperation. A task-oriented operational quality measure, (TOQd) is defined by evaluating dual-arm dynamic manipulability in terms of given task requirements. TOQd is used in dual-arm joint configuration optimization. Simulation results are shown. A complete set of forward dynamic equations for a dual-arm system is derived, and dual-arm dynamic operational quality measures for various modes of dual-arm cooperation allowing sliding contacts are established.

  4. Chemical detection with hyperspectral lidar using dual frequency combs.

    PubMed

    Boudreau, Sylvain; Levasseur, Simon; Perilla, Carlos; Roy, Simon; Genest, Jérôme

    2013-03-25

    High-resolution spectral lidar measurements using dual frequency combs as a source is presented. The technique enables the range-resolved measurement of fine spectral features, such as gas absorption lines, provided that a suitable scatterer is present in the scene. Measurements of HCN absorption lines at 20 meters are presented, with a water droplet cloud and a diffusely reflective surface as scatterers.

  5. Dual ion beam processed diamondlike films for industrial applications

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Kussmaul, M. T.; Banks, B. A.; Sovey, J. S.

    1991-01-01

    Single and dual beam ion source systems are used to generate amorphous diamondlike carbon (DLC) films, which were evaluated for a variety of applications including protective coatings on transmitting materials, power electronics as insulated gates and corrosion resistant barriers. A list of the desirable properties of DLC films along with potential applications are presented.

  6. Toward Personhood: Uniting the Professional Woman's "Dual Careers."

    ERIC Educational Resources Information Center

    Lischin, Stevi; Smith, Robert Charles

    While professional women may experience their "dual careers" at home and at work as a source of inner fragmentation, this fragmentation can be a vehicle for developing a greater sense of personhood. Recent data show that women who combine work, marriage, and motherhood are experiencing more general psychological well being than are other women.…

  7. The evaluation of dual cement resins in orthodontic bonding.

    PubMed

    Smith, R T; Shivapuja, P K

    1993-05-01

    Dual-cement resins are composite resins that are both light activated and chemically cured. They can be cured completely with a visible light source or by the catalyst and base reaction of the material. With the control of setting time, dual cements appear to offer clinicians advantages in orthodontic bonding. The purposes of the present research are to compare various dual cements in regard to orthodontic bonding and to evaluate them in relation to currently used chemically cured and light-cured composite resins for bonding stainless steel mesh-backed orthodontic brackets. Seven currently available orthodontic bonding systems (three light cured and four chemically cured) and three dual cements were evaluated. Each of the 10 groups contained 15 noncarious mandibular incisors. Mandibular incisor brackets were bonded to the teeth in accordance with the manufacturer's recommendation. After bonding, the teeth were stored for 5 days in water at 37 degrees C. An Instron machine (Instron Corp., Canton, Mass.) was used to test samples. All samples were compared with Concise orthodontic bonding composite (3M, St. Paul, Minn.). The results of this investigation show that it is possible to bond solid, mesh-backed metal orthodontic brackets to teeth with a dual cement. The shear bond strengths of the dual cements, as tested in the laboratory, should be adequate to withstand normal orthodontic forces. Increased control of the setting time of the dual cements will allow the clinician more time to correctly position brackets and to remove excess resin before curing. In addition, the clinician can be assured of complete polymerization with the chemical properties of the dual cement resins.

  8. Dual broadband metamaterial absorber.

    PubMed

    Kim, Young Ju; Yoo, Young Joon; Kim, Ki Won; Rhee, Joo Yull; Kim, Yong Hwan; Lee, YoungPak

    2015-02-23

    We propose polarization-independent and dual-broadband metamaterial absorbers at microwave frequencies. This is a periodic meta-atom array consisting of metal-dielectric-multilayer truncated cones. We demonstrate not only one broadband absorption from the fundamental magnetic resonances but additional broadband absorption in high-frequency range using the third-harmonic resonance, by both simulation and experiment. In simulation, the absorption was over 90% in 3.93-6.05 GHz, and 11.64-14.55 GHz. The corresponding experimental absorption bands over 90% were 3.88-6.08 GHz, 9.95-10.46 GHz and 11.86-13.84 GHz, respectively. The origin of absorption bands was elucidated. Furthermore, it is independent of polarization angle owing to the multilayered circular structures. The design is scalable to smaller size for the infrared and the visible ranges.

  9. Dual-Mode Combustion

    NASA Technical Reports Server (NTRS)

    Goyne, Christopher P.; McDaniel, James C.

    2002-01-01

    The Department of Mechanical and Aerospace Engineering at the University of Virginia has conducted an investigation of the mixing and combustion processes in a hydrogen fueled dual-mode scramjet combustor. The experiment essentially consisted of the "direct connect" continuous operation of a Mach 2 rectangular combustor with a single unswept ramp fuel injector. The stagnation enthalpy of the test flow simulated a flight Mach number of 5. Measurements were obtained using conventional wall instrumentation and laser based diagnostics. These diagnostics included, pressure and wall temperature measurements, Fuel Plume Imaging (FPI) and Particle Image Velocimetry (PIV). A schematic of the combustor configuration and a summary of the measurements obtained are presented. The experimental work at UVa was parallel by Computational Fluid Dynamics (CFD) work at NASA Langley. The numerical and experiment results are compared in this document.

  10. Integrated Dual Imaging Detector

    NASA Technical Reports Server (NTRS)

    Rust, David M.

    1999-01-01

    A new type of image detector was designed to simultaneously analyze the polarization of light at all picture elements in a scene. The integrated Dual Imaging detector (IDID) consists of a lenslet array and a polarizing beamsplitter bonded to a commercial charge coupled device (CCD). The IDID simplifies the design and operation of solar vector magnetographs and the imaging polarimeters and spectroscopic imagers used, for example, in atmosphere and solar research. When used in a solar telescope, the vector magnetic fields on the solar surface. Other applications include environmental monitoring, robot vision, and medical diagnoses (through the eye). Innovations in the IDID include (1) two interleaved imaging arrays (one for each polarization plane); (2) large dynamic range (well depth of 10(exp 5) electrons per pixel); (3) simultaneous readout and display of both images; and (4) laptop computer signal processing to produce polarization maps in field situations.

  11. Dual Tank Fuel System

    DOEpatents

    Wagner, Richard William; Burkhard, James Frank; Dauer, Kenneth John

    1999-11-16

    A dual tank fuel system has primary and secondary fuel tanks, with the primary tank including a filler pipe to receive fuel and a discharge line to deliver fuel to an engine, and with a balance pipe interconnecting the primary tank and the secondary tank. The balance pipe opens close to the bottom of each tank to direct fuel from the primary tank to the secondary tank as the primary tank is filled, and to direct fuel from the secondary tank to the primary tank as fuel is discharged from the primary tank through the discharge line. A vent line has branches connected to each tank to direct fuel vapor from the tanks as the tanks are filled, and to admit air to the tanks as fuel is delivered to the engine.

  12. Miniaturized Dual-Band Bandpass Filter Using Embedded Dual-Mode Resonator with Controllable Bandwidths

    NASA Astrophysics Data System (ADS)

    Zhu, Chuanming; Xu, Jin; Kang, Wei; Hu, Zhenxin; Wu, Wen

    2016-09-01

    In this paper, a miniaturized dual-band bandpass filter (DB-BPF) using embedded dual-mode resonator (DMR) with controllable bandwidths is proposed. Two passbands are generated by two sets of resonators operating at two different frequencies. One set of resonators is utilized not only as the resonant elements that yield the lower passband, but also as the feeding structures with source-load coupling to excite the other to produce the upper passband. Sufficient degrees of freedom are achieved to control the center frequencies and bandwidths of two passbands. Moreover, multiple transmission zeros (TZs) are created to improve the passband selectivity of the filter. The design of the filter has been demonstrated by the measurement. The filter features not only miniaturized circuit sizes, low insertion loss, independently controllable central frequencies, but also controllable bandwidths and TZs.

  13. Widely-tunable, Compact, and Portable Terahertz Source Based on Intracavity Difference-Frequency Generation in Dual-Frequency Yb:YAG Laser for Identification and Detection of Biological Agents

    DTIC Science & Technology

    2011-06-15

    2011 W911NF-11-C-0044 Period of Performance December 9, 2010 – June 6, 2011 “Widely-tunable, compact, and portable terahertz source based on...combination acoustic-optic and passive Q-switch for LIDAR applications,” JWA46, CLEO 2011. [5] Y. Jiang, D. Li, Y. J. Ding, and I. B. Zotova, “ Terahertz ...Generation Based on Parametric Conversion: From Saturation of Conversion Efficiency to Back Conversion,” Opt. Lett. 36, 1608-1610 (2011). [6] Q. Gan , Z

  14. Dual-mode acoustic wave biosensors microarrays

    NASA Astrophysics Data System (ADS)

    Auner, Gregory W.; Shreve, Gina; Ying, Hao; Newaz, Golam; Hughes, Chantelle; Xu, Jianzeng

    2003-04-01

    We have develop highly sensitive and selective acoustic wave biosensor arrays with signal analysis systems to provide a fingerprint for the real-time identification and quantification of a wide array of bacterial pathogens and environmental health hazards. We have developed an unique highly sensitive dual mode acoustic wave platform prototype that, when combined with phage based selective detection elements, form a durable bacteria sensor. Arrays of these new real-time biosensors are integrated to form a biosensor array on a chip. This research and development program optimizes advanced piezoelectric aluminum nitride wide bandgap semiconductors, novel micromachining processes, advanced device structures, selective phage displays development and immobilization techniques, and system integration and signal analysis technology to develop the biosensor arrays. The dual sensor platform can be programmed to sense in a gas, vapor or liquid environment by switching between acoustic wave resonate modes. Such a dual mode sensor has tremendous implications for applications involving monitoring of pathogenic microorganisms in the clinical setting due to their ability to detect airborne pathogens. This provides a number of applications including hospital settings such as intensive care or other in-patient wards for the reduction of nosocomial infections and maintenance of sterile environments in surgical suites. Monitoring for airborn pathogen transmission in public transportation areas such as airplanes may be useful for implementation of strategies for redution of airborn transmission routes. The ability to use the same sensor in the liquid sensing mode is important for tracing the source of airborn pathogens to local liquid sources. Sensing of pathogens in saliva will be useful for sensing oral pathogens and support of decision-making strategies regarding prevention of transmission and support of treatment strategies.

  15. Dual-Phase Nozzle Flow.

    DTIC Science & Technology

    1982-10-01

    Two-phase 20. A T RACT (0.31lmm 401 teV9 i 01 000* u...in #CMIdR@0fr &V WNHI& WARNeJ A revieW or the dual-phase -ower system was made. This study ...pr-et5 ._ lnering Dean of Science and Engineering J* ABSTRACT A review of the dual-phase power system was made. This study focused on the multi...be studied in detail, but first a review of the dual-phase cycle will be carried out from information obtained from References 1 and 2. Reference 1

  16. Dual X-ray absorptiometry

    NASA Astrophysics Data System (ADS)

    Altman, Albert; Aaron, Ronald

    2012-07-01

    Dual X-ray absorptiometry is widely used in analyzing body composition and imaging. Both the method and its limitations are related to the Compton and photoelectric contributions to the X-ray attenuation coefficients of materials.

  17. The Man of Dual Nationality.

    ERIC Educational Resources Information Center

    Abe, Yoshio

    1985-01-01

    Presents an English translation of the first few pages, set in a Japanese internment camp in the U.S. during World War II, of a Japanese novel about the problems of dual nationality and personal identity. (KH)

  18. Identification and dual adaptive control of a turbojet engine

    NASA Technical Reports Server (NTRS)

    Merrill, W.; Leininger, G.

    1979-01-01

    The objective of this paper is to utilize the design methods of modern control theory to realize a 'dual-adaptive' feedback control unit for a highly non-linear single spool airbreathing turbojet engine. Using a very detailed and accurate simulation of the non-linear engine as the data source, linear operating point models of unspecified dimension are identified. Feedback control laws are designed at each operating point for a prespecified set of sampling rates using sampled-data output regulator theory. The control system sampling rate is determined by an adaptive sampling algorithm in correspondence with turbojet engine performance. The result is a 'dual-adpative' control law that is functionally dependent upon the sampling rate selected and environmental operating conditions. Simulation transients demonstrate the utility of the dual-adaptive design to improve on-board computer utilization while maintaining acceptable levels of engine performance.

  19. Optical force and torque on dipolar dual chiral particles

    NASA Astrophysics Data System (ADS)

    Rahimzadegan, A.; Fruhnert, M.; Alaee, R.; Fernandez-Corbaton, I.; Rockstuhl, C.

    2016-09-01

    On the one hand, electromagnetic dual particles preserve the helicity of light upon interaction. On the other hand, chiral particles respond differently to light of opposite helicity. These two properties on their own constitute a source of fascination. Their combined action, however, is less explored. Here, we study on analytical grounds the force and torque as well as the optical cross sections of dual chiral particles in the dipolar approximation exerted by a particular wave of well-defined helicity: A circularly polarized plane wave. We put emphasis on particles that possess a maximally electromagnetic chiral and hence dual response. Besides the analytical insights, we also investigate the exerted optical force and torque on a real particle using the example of a metallic helix that is designed to approach the maximal electromagnetic chirality condition. Various applications in the context of optical sorting but also nanorobotics can be foreseen considering the particles studied in this contribution.

  20. Identification and dual adaptive control of a turbojet engine

    NASA Technical Reports Server (NTRS)

    Merrill, W.; Leininger, G.

    1979-01-01

    The objective of this paper is to utilize the design methods of modern control theory to realize a dual-adaptive feedback control unit for a highly nonlinear single spool airbreathing turbojet engine. Using a very detailed and accurate simulation of the nonlinear engine as the data source, linear operating point models of unspecified dimension are identified. Feedback control laws are designed at each operating point for a prespecified set of sampling rates using sampled-data output regulator theory. The control system sampling rate is determined by an adaptive sampling algorithm in correspondence with turbojet engine performance. The result is a dual-adaptive control law that is functionally dependent upon the sampling rate selected and environmental operating conditions. Simulation transients demonstrate the utility of the dual-adaptive design to improve on-board computer utilization while maintaining acceptable levels of engine performance.

  1. Stochastic image reconstruction for a dual-particle imaging system

    NASA Astrophysics Data System (ADS)

    Hamel, M. C.; Polack, J. K.; Poitrasson-Rivière, A.; Flaska, M.; Clarke, S. D.; Pozzi, S. A.; Tomanin, A.; Peerani, P.

    2016-02-01

    Stochastic image reconstruction has been applied to a dual-particle imaging system being designed for nuclear safeguards applications. The dual-particle imager (DPI) is a combined Compton-scatter and neutron-scatter camera capable of producing separate neutron and photon images. The stochastic origin ensembles (SOE) method was investigated as an imaging method for the DPI because only a minimal estimation of system response is required to produce images with quality that is comparable to common maximum-likelihood methods. This work contains neutron and photon SOE image reconstructions for a 252Cf point source, two mixed-oxide (MOX) fuel canisters representing point sources, and the MOX fuel canisters representing a distributed source. Simulation of the DPI using MCNPX-PoliMi is validated by comparison of simulated and measured results. Because image quality is dependent on the number of counts and iterations used, the relationship between these quantities is investigated.

  2. Unattended Dual Current Monitor

    SciTech Connect

    Newell, Matthew R.; Parker, Robert F.; Jones, David C.

    2016-08-11

    The Unattended Dual Current Monitor (UDCM) is an ideal solution for current measurement needs such as ion chamber gamma measurements. The UDCM has two independent inputs and each input detects currents in two user selectable ranges, -0.2nA to -20nA or -20nA to -2uA. Measurement results can be retrieved via an Ethernet connection or by monitoring the TTL output pulses with a simple counter. Measurement data is also stored on a user accessible micro-SD card and automatically downloaded to a USB flash drive. A programmable negative High Voltage (HV) power supply provides detector bias voltages from 0 to -1,000V. The UDCM is fully compatible with the IAEA Multi Instrument Collect (MIC) software and responds to the existing MiniGRAND commands. The Ethernet port provides an IAEA RAINSTORM compliant data transfer and data security interface. The UDCM produces TTL pulses at a rate proportional to the input current, 100cps/nA. The UDCM can simplify instrumentation needs by enabling the use of a simple pulse counter for both neutron and gamma measurements. The UDCM is a simple instrument, inexpensive to manufacturer and designed for reliability.

  3. Fast dual tomography

    NASA Astrophysics Data System (ADS)

    Carrion, Philip M.

    1990-09-01

    This paper can be considered as a continuation of the work by Carrion and Carneiro (1989), where a generalized approach to linearized inversion of geophysical data was developed. Their method allows one to incorporate virtually any constraints in the inversion and reformulate the problem in the dual space of Langrangian multipliers (see also Carrion, 1989a). The constrained tomography makes traveltime inversion robust: it automatically rejects “bad data” which correspond to solutions beyond the chosen constraints and allows one to start inversion with an arbitrary chosen initial model.In this paper, I will derive basic formulas for constrained tomographic imaging that can be used in such areas of geophysics as global mapping of the earth interior, exploration geophysics, etc. The method is fast: an example that will be shown in the paper took only 6 min. of VAX CPU time. Had the conventional least-squares matrix inversion been used it would have taken more than 10 hours of the CPU time to solve the same problem.

  4. Neuroretinitis with dual infections

    PubMed Central

    Kiu, Kwong-Han; Hanizasurana, Hashim; Zunaina, Embong

    2015-01-01

    A 22-year-old Malay female presented with left eye floaters for 2 weeks, associated with temporal visual field defect and metamorphopsia for 3 days. She has a guinea pig and a hedgehog at home, but denied being bitten or scratched by them. Her visual acuity at presentation was 6/12 on the left eye and 6/6 on the right eye. Her left eye relative afferent pupillary defect was barely positive with mild anterior chamber reaction. Fundus examination of the left eye showed mild vitritis, swollen optic disc with macular star, crops of active choroidal lesions at superonasal retina with a linear arrangement in the form of migratory track nasally. However, there were no nematodes seen on fundus examination. Investigations showed normal full blood count with no eosinophilia and positive serology test for Bartonella henselae. She was diagnosed to have dual infection – diffuse unilateral subacute neuroretinitis (DUSN), based on the presence of crops of choroidal lesions with migratory track, and cat scratch disease (CSD) based on a positive serological test. She was treated with oral albendazole 400 mg 12 hourly for 6 weeks for DUSN and oral doxycycline 100 mg 12 hourly for 4 weeks for CSD. Focal laser had been applied to the area of migratory track in the left eye. Her left eye vision improved to 6/6 at 1 month after treatment, with resolution of neuroretinitis. PMID:26527902

  5. Dual porphyrias revisited.

    PubMed

    Poblete-Gutiérrez, Pamela; Badeloe, Sadhanna; Wiederholt, Tonio; Merk, Hans F; Frank, Jorge

    2006-09-01

    The porphyrias are clinically and genetically heterogeneous metabolic diseases, which predominantly result from a hereditary dysfunction in the pathway of haeme biosynthesis. Currently, at least eight different forms of porphyrias can be differentiated, all of them characterized by a specific enzyme deficiency that is either inherited in an autosomal-dominant fashion, autosomal recessively or, in the case of porphyria cutanea tarda, might also be acquired. All genes encoding these enzymes have been cloned and several mutations underlying the different types of porphyrias have been reported. Traditionally, the diagnosis of porphyria is made on the basis of clinical symptoms, characteristic biochemical findings and enzyme assays. In some porphyria patients and families, however, these diagnostic tools can reveal simultaneous findings compatible with two different forms of porphyria, a phenomenon referred to as dual porphyria. Here, we give an overview on what is currently known about these peculiar variants of porphyria and suggest that, whenever feasible, molecular genetic analysis should complement the analytical techniques used to characterize patients and families in which a double enzymatic deficiency within the haeme biosynthetic pathway is assumed.

  6. Non-Abelian dual superconductivity in SU(3) Yang-Mills theory: Dual Meissner effect and type of the vacuum

    NASA Astrophysics Data System (ADS)

    Shibata, Akihiro; Kondo, Kei-Ichi; Kato, Seikou; Shinohara, Toru

    2013-03-01

    We have proposed the non-Abelian dual superconductivity picture for quark confinement in the SU(3) Yang-Mills (YM) theory, and have given numerical evidences for the restricted-field dominance and the non-Abelian magnetic monopole dominance in the string tension by applying a new formulation of the YM theory on a lattice. To establish the non-Abelian dual superconductivity picture for quark confinement, we have observed the non-Abelian dual Meissner effect in the SU(3) Yang-Mills theory by measuring the chromoelectric flux created by the quark-antiquark source, and the non-Abelian magnetic monopole currents induced around the flux. We conclude that the dual superconductivity of the SU(3) Yang-Mills theory is strictly the type I and that this type of dual superconductivity is reproduced by the restricted field and the non-Abelian magnetic monopole part, in sharp contrast to the SU(2) case: the border of type I and type II.

  7. Dual key speech encryption algorithm based underdetermined BSS.

    PubMed

    Zhao, Huan; He, Shaofang; Chen, Zuo; Zhang, Xixiang

    2014-01-01

    When the number of the mixed signals is less than that of the source signals, the underdetermined blind source separation (BSS) is a significant difficult problem. Due to the fact that the great amount data of speech communications and real-time communication has been required, we utilize the intractability of the underdetermined BSS problem to present a dual key speech encryption method. The original speech is mixed with dual key signals which consist of random key signals (one-time pad) generated by secret seed and chaotic signals generated from chaotic system. In the decryption process, approximate calculation is used to recover the original speech signals. The proposed algorithm for speech signals encryption can resist traditional attacks against the encryption system, and owing to approximate calculation, decryption becomes faster and more accurate. It is demonstrated that the proposed method has high level of security and can recover the original signals quickly and efficiently yet maintaining excellent audio quality.

  8. A dual reciprocal boundary element formulation for viscous flows

    NASA Technical Reports Server (NTRS)

    Lafe, Olu

    1993-01-01

    The advantages inherent in the boundary element method (BEM) for potential flows are exploited to solve viscous flow problems. The trick is the introduction of a so-called dual reciprocal technique in which the convective terms are represented by a global function whose unknown coefficients are determined by collocation. The approach, which is necessarily iterative, converts the governing partial differential equations into integral equations via the distribution of fictitious sources or dipoles of unknown strength on the boundary. These integral equations consist of two parts. The first is a boundary integral term, whose kernel is the unknown strength of the fictitious sources and the fundamental solution of a convection-free flow problem. The second part is a domain integral term whose kernel is the convective portion of the governing PDEs. The domain integration can be transformed to the boundary by using the dual reciprocal (DR) concept. The resulting formulation is a pure boundary integral computational process.

  9. Virtual flight simulation of a dual rotor micro air vehicle

    NASA Astrophysics Data System (ADS)

    Cai, Hongming

    2015-02-01

    In this paper, a new computational method is developed based on computational fluid dynamics (CFD) coupled with rigid body dynamics (RBD) and flight control law in an in-house programmed source code. The CFD solver is established based on momentum source method, preconditioning method, lower-upper symmetric Gauss-Seidel iteration method, and moving overset grid method. Two-equation shear-stress transport k - ω turbulence model is employed to close the governing equations. Third-order Adams prediction-correction method is used to couple CFD and RBD in the inner iteration. The wing-rock motion of the delta wing is simulated to validate the capability of the computational method for virtual flight simulation. Finally, the developed computational method is employed to simulate the longitudinal virtual flight of a dual rotor micro air vehicle (MAV). Results show that the computational method can simulate the virtual flight of the dual rotor MAV.

  10. UWB dual burst transmit driver

    SciTech Connect

    Dallum, Gregory E; Pratt, Garth C; Haugen, Peter C; Zumstein, James M; Vigars, Mark L; Romero, Carlos E

    2012-04-17

    A dual burst transmitter for ultra-wideband (UWB) communication systems generates a pair of precisely spaced RF bursts from a single trigger event. An input trigger pulse produces two oscillator trigger pulses, an initial pulse and a delayed pulse, in a dual trigger generator. The two oscillator trigger pulses drive a gated RF burst (power output) oscillator. A bias driver circuit gates the RF output oscillator on and off and sets the RF burst packet width. The bias driver also level shifts the drive signal to the level that is required for the RF output device.

  11. Dual porosity gas evolving electrode

    DOEpatents

    Townsend, Carl W.

    1994-01-01

    A dual porosity electrode for use in thermoelectrochemical systems where simultaneous transport of gas and liquid into and/or out of the electrode is required. The electrode includes catalytic electrode particles having diameters ranging from about 25 to 100 angstroms. The catalytic electrode particles are anchored to a support network in clusters which have internal pores ranging in size from 25 to 100 angstroms. The pores between the clusters range in size from between about 1 to 20 microns. A method for making the dual porosity electrodes is also disclosed.

  12. Dual porosity gas evolving electrode

    DOEpatents

    Townsend, C.W.

    1994-11-15

    A dual porosity electrode is described for use in thermoelectrochemical systems where simultaneous transport of gas and liquid into and/or out of the electrode is required. The electrode includes catalytic electrode particles having diameters ranging from about 25 to 100 angstroms. The catalytic electrode particles are anchored to a support network in clusters which have internal pores ranging in size from 25 to 100 angstroms. The pores between the clusters range in size from between about 1 to 20 microns. A method for making the dual porosity electrodes is also disclosed.

  13. Dual-keel electrodynamic maglev system

    SciTech Connect

    He, J.; Wang, Z.; Rote, D.M.; Coffey, H.T.; Hull, J.R.; Mulcahy, T.M.; Cai, Y.

    1995-12-31

    A propulsion and stabilization system with a plurality of superconducting magnetic devices affixed to the dual-keels of a vehicle, where the superconducting magnetic devices produce a magnetic field when energized. The system also includes a plurality of figure-eight shaped null-flux coils affixed to opposing vertical sides of slots in a guideway. The figure-eight shaped null-flux coils are vertically oriented, laterally cross-connected in parallel, longitudinally connected in series, and continue the length of the vertical slots providing levitation and guidance force. An external power source energizes the figure-eight shaped null-flux coils to create a magnetic traveling wave that interacts with the magnetic field produced by the superconducting magnets to impart motion to the vehicle.

  14. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, D.D.

    A chromatographic system is described that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a nontransparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extreme low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  15. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, Don D.

    1985-01-01

    A chromatographic system that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a non-transparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extremely low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  16. Dual-keel electrodynamic maglev system

    DOEpatents

    He, Jianliang; Wang, Zian; Rote, Donald M.; Coffey, Howard T.; Hull, John R.; Mulcahy, Thomas M.; Cal, Yigang

    1996-01-01

    A propulsion and stabilization system with a plurality of superconducting magnetic devices affixed to the dual-keels of a vehicle, where the superconducting magnetic devices produce a magnetic field when energized. The system also includes a plurality of figure-eight shaped null-flux coils affixed to opposing vertical sides of slots in a guideway. The figure-eight shaped null-flux coils are vertically oriented, laterally cross-connected in parallel, longitudinally connected in series, and continue the length of the vertical slots providing levitation and guidance force. An external power source energizes the figure-eight shaped null-flux coils to create a magnetic traveling wave that interacts with the magnetic field produced by the superconducting magnets to impart motion to the vehicle.

  17. Dual-keel electrodynamic maglev system

    DOEpatents

    He, J.L.; Wang, Z.; Rote, D.M.; Coffey, H.T.; Hull, J.R.; Mulcahy, T.M.; Cal, Y.

    1996-12-24

    A propulsion and stabilization system is disclosed with a plurality of superconducting magnetic devices affixed to the dual-keels of a vehicle, where the superconducting magnetic devices produce a magnetic field when energized. The system also includes a plurality of figure-eight shaped null-flux coils affixed to opposing vertical sides of slots in a guideway. The figure-eight shaped null-flux coils are vertically oriented, laterally cross-connected in parallel, longitudinally connected in series, and continue the length of the vertical slots providing levitation and guidance force. An external power source energizes the figure-eight shaped null-flux coils to create a magnetic traveling wave that interacts with the magnetic field produced by the superconducting magnets to impart motion to the vehicle. 6 figs.

  18. Dual Telecentric Lens System For Projection Onto Tilted Toroidal Screen

    NASA Technical Reports Server (NTRS)

    Gold, Ronald S.; Hudyma, Russell M.

    1995-01-01

    System of two optical assemblies for projecting image onto tilted toroidal screen. One projection lens optimized for red and green spectral region; other for blue. Dual-channel approach offers several advantages which include: simplified color filtering, simplified chromatic aberration corrections, less complex polarizing prism arrangement, and increased throughput of blue light energy. Used in conjunction with any source of imagery, designed especially to project images formed by reflection of light from liquid-crystal light valve (LCLV).

  19. Dual-Doppler Feasibility Study

    NASA Technical Reports Server (NTRS)

    Huddleston, Lisa L.

    2012-01-01

    When two or more Doppler weather radar systems are monitoring the same region, the Doppler velocities can be combined to form a three-dimensional (3-D) wind vector field thus providing for a more intuitive analysis of the wind field. A real-time display of the 3-D winds can assist forecasters in predicting the onset of convection and severe weather. The data can also be used to initialize local numerical weather prediction models. Two operational Doppler Radar systems are in the vicinity of Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS); these systems are operated by the 45th Space Wing (45 SW) and the National Weather Service Melbourne, Fla. (NWS MLB). Dual-Doppler applications were considered by the 45 SW in choosing the site for the new radar. Accordingly, the 45th Weather Squadron (45 WS), NWS MLB and the National Aeronautics and Space Administration tasked the Applied Meteorology Unit (AMU) to investigate the feasibility of establishing dual-Doppler capability using the two existing systems. This study investigated technical, hardware, and software requirements necessary to enable the establishment of a dual-Doppler capability. Review of the available literature pertaining to the dual-Doppler technique and consultation with experts revealed that the physical locations and resulting beam crossing angles of the 45 SW and NWS MLB radars make them ideally suited for a dual-Doppler capability. The dual-Doppler equations were derived to facilitate complete understanding of dual-Doppler synthesis; to determine the technical information requirements; and to determine the components of wind velocity from the equation of continuity and radial velocity data collected by the two Doppler radars. Analysis confirmed the suitability of the existing systems to provide the desired capability. In addition, it is possible that both 45 SW radar data and Terminal Doppler Weather Radar data from Orlando International Airport could be used to alleviate any

  20. Dual excitation acoustic paramagnetic logging tool

    DOEpatents

    Vail, III, William B.

    1989-01-01

    New methods and apparatus are disclosed which allow measurement of the presence of oil and water in gelogical formations using a new physical effect called the Acoustic Paramagnetic Logging Effect (APLE). The presence of petroleum in formation causes a slight increase in the earth's magnetic field in the vicinity of the reservoir. This is the phenomena of paramagnetism. Application of an acoustic source to a geological formation at the Larmor frequency of the nucleous present causes the paramagnetism of the formation to disappear. This results in a decrease in the earth's magnetic field in the vicinity of the oil bearing formation. Repetitively frequency sweeping the acoustic source through the Larmor frequency of the nucleons present (approx. 2 kHz) causes an amplitude modulation of the earth's magnetic field which is a consequence of the APLE. The amplitude modulation of the earth's magnetic field is measured with an induction coil gradiometer and provides a direct measure of the amount of oil and water in the excitation zone of the formation. The phase of the signal is used to infer the longitudinal relaxation times of the fluids present, which results in the ability in general to separate oil and water and to measure the viscosity of the oil present. Such measurements may be preformed in open boreholes and in cased well bores. The Dual Excitation Acoustic Paramagnetic Logging Tool employing two acoustic sources is also described.

  1. Dual excitation acoustic paramagnetic logging tool

    DOEpatents

    Vail, W.B. III.

    1989-02-14

    New methods and apparatus are disclosed which allow measurement of the presence of oil and water in geological formations using a new physical effect called the Acoustic Paramagnetic Logging Effect (APLE). The presence of petroleum in formation causes a slight increase in the earth's magnetic field in the vicinity of the reservoir. This is the phenomena of paramagnetism. Application of an acoustic source to a geological formation at the Larmor frequency of the nucleons present causes the paramagnetism of the formation to disappear. This results in a decrease in the earth's magnetic field in the vicinity of the oil bearing formation. Repetitively frequency sweeping the acoustic source through the Larmor frequency of the nucleons present (approx. 2 kHz) causes an amplitude modulation of the earth's magnetic field which is a consequence of the APLE. The amplitude modulation of the earth's magnetic field is measured with an induction coil gradiometer and provides a direct measure of the amount of oil and water in the excitation zone of the formation. The phase of the signal is used to infer the longitudinal relaxation times of the fluids present, which results in the ability in general to separate oil and water and to measure the viscosity of the oil present. Such measurements may be performed in open boreholes and in cased well bores. The Dual Excitation Acoustic Paramagnetic Logging Tool employing two acoustic sources is also described. 6 figs.

  2. Dual Enrollment in Spanish: One Working Model

    ERIC Educational Resources Information Center

    Bloom, Melanie; Chambers, Laura

    2009-01-01

    Dual enrollment is now a nation-wide phenomenon as all 50 states currently offer some form of dual-enrollment program to secondary-school students (Karp, Bailey, Hughes, and Fermin 2005). However, dual enrollment itself is often difficult to define as programs vary from school to school (Jordan, Cavalluzzo, and Corallo 2006). Therefore, language…

  3. 7 CFR 247.19 - Dual participation.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 4 2010-01-01 2010-01-01 false Dual participation. 247.19 Section 247.19 Agriculture... CHILD NUTRITION PROGRAMS COMMODITY SUPPLEMENTAL FOOD PROGRAM § 247.19 Dual participation. (a) What must State and local agencies do to prevent and detect dual participation? The State agency must work...

  4. 7 CFR 247.19 - Dual participation.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 4 2011-01-01 2011-01-01 false Dual participation. 247.19 Section 247.19 Agriculture... CHILD NUTRITION PROGRAMS COMMODITY SUPPLEMENTAL FOOD PROGRAM § 247.19 Dual participation. (a) What must State and local agencies do to prevent and detect dual participation? The State agency must work...

  5. Dual Processing and Diagnostic Errors

    ERIC Educational Resources Information Center

    Norman, Geoff

    2009-01-01

    In this paper, I review evidence from two theories in psychology relevant to diagnosis and diagnostic errors. "Dual Process" theories of thinking, frequently mentioned with respect to diagnostic error, propose that categorization decisions can be made with either a fast, unconscious, contextual process called System 1 or a slow, analytical,…

  6. Dual characterizations of optimal systems.

    NASA Technical Reports Server (NTRS)

    Chan, W. L.; Leininger, G. G.

    1972-01-01

    The complementary variational principle developed in a Hilbert space setting provides a duality principle in the calculus of variations with dynamic constraints. This concept is adopted in this paper to investigate dual characterizations of optimal control systems. Systems under consideration include those with dynamics governed by linear ordinary differential equations, linear partial differential equations and non-linear ordinary differential equations.

  7. Dual-Laser-Pulse Ignition

    NASA Technical Reports Server (NTRS)

    Trinh, Huu; Early, James W.; Thomas, Matthew E.; Bossard, John A.

    2006-01-01

    A dual-pulse laser (DPL) technique has been demonstrated for generating laser-induced sparks (LIS) to ignite fuels. The technique was originally intended to be applied to the ignition of rocket propellants, but may also be applicable to ignition in terrestrial settings in which electric igniters may not be suitable.

  8. Dual shell pressure balanced vessel

    DOEpatents

    Fassbender, Alexander G.

    1992-01-01

    A dual-wall pressure balanced vessel for processing high viscosity slurries at high temperatures and pressures having an outer pressure vessel and an inner vessel with an annular space between the vessels pressurized at a pressure slightly less than or equivalent to the pressure within the inner vessel.

  9. Dual redundant core memory systems

    NASA Technical Reports Server (NTRS)

    Hull, F. E.

    1972-01-01

    Electronic memory system consisting of series redundant drive switch circuits, triple redundant majority voted memory timing functions, and two data registers to provide functional dual redundancy is described. Signal flow through the circuits is illustrated and equence of events which occur within the memory system is explained.

  10. Dual x-ray absorptiometry

    NASA Astrophysics Data System (ADS)

    Altman, Albert; Aaron, Ronald

    2011-04-01

    Dual x-ray absorptiometry is widely used in analyzing body composition and imaging. We discuss the physics of the method and exhibit its limitations and show it is related to the Compton and photoelectric contributions to the x-ray absorption coefficients of materials.

  11. Dual channel electrostimulation in pain.

    PubMed

    Devulder, J; De Laat, M; Rolly, G

    1998-06-01

    Spinal cord stimulation is an accepted treatment for neuropathic pain. Technical advances in electrode design and better patient selection have led to better and sustained pain control by these devices. Multilead electrical stimulation is the latest innovation in implantable electrostimulation (Mattrix, Medtronic Minneapolis, USA). Two combined multipolar leads connected to a radiofrequency--coupled system can deliver electrical pulses of various amplitudes and pulse widths at different dermatome levels. Single stimulation is applied with different electrode configurations using both electrodes with identical stimulation parameters. In dual stimulation, the amplitude and the pulse width can vary between the electrode configurations. Dual channel stimulation helps steering stimulation paresthesias. Three patients illustrate the technical advantages of dual channel electrostimulation in the pain relief at multiple sites. Two patients with failed back surgery syndrome obtained more easily stimulation-induced paresthesias in the back and the legs. Dual channel stimulation is cost saving in patients implanted with two electrodes. This is presented in a third patient with an electrode in the thalamus--as pain treatment for cervicobrachialgia and a second in the epidural space--as treatment for the failed back surgery syndrome. These electrodes were connected to the Mattrix stimulator.

  12. Self-Dual Conformal Gravity

    NASA Astrophysics Data System (ADS)

    Dunajski, Maciej; Tod, Paul

    2014-10-01

    We find necessary and sufficient conditions for a Riemannian four-dimensional manifold ( M, g) with anti-self-dual Weyl tensor to be locally conformal to a Ricci-flat manifold. These conditions are expressed as the vanishing of scalar and tensor conformal invariants. The invariants obstruct the existence of parallel sections of a certain connection on a complex rank-four vector bundle over M. They provide a natural generalisation of the Bach tensor which vanishes identically for anti-self-dual conformal structures. We use the obstructions to demonstrate that LeBrun's anti-self-dual metrics on connected sums of s are not conformally Ricci-flat on any open set. We analyze both Riemannian and neutral signature metrics. In the latter case we find all anti-self-dual metrics with a parallel real spinor which are locally conformal to Einstein metrics with non-zero cosmological constant. These metrics admit a hyper-surface orthogonal null Killing vector and thus give rise to projective structures on the space of β-surfaces.

  13. Dual function conducting polymer diodes

    DOEpatents

    Heeger, Alan J.; Yu, Gang

    1996-01-01

    Dual function diodes based on conjugated organic polymer active layers are disclosed. When positively biased the diodes function as light emitters. When negatively biased they are highly efficient photodiodes. Methods of preparation and use of these diodes in displays and input/output devices are also disclosed.

  14. KC-X: Dual Source Procurement Is the Only Option

    DTIC Science & Technology

    2010-04-01

    F-15 non-mission AU/ACSC/Gilpatrick, B /AY10 6 critical flight operations were suspended following the crash of a Missouri Air National Guard...of jet fuel. 37 Despite the significantly larger KC-10 and its mammoth 350,000 pound fuel capacity, there are debates about which is more capable...tankers) simply ran out of space. 53 The larger the aircraft the more space necessary for parking , maintenance, and general support functions. When

  15. Cardiac amyloidosis imaged by dual-source computed tomography.

    PubMed

    Marwan, Mohamed; Pflederer, Tobias; Ropers, Dieter; Schmid, Michael; Wasmeier, Gerald; Söder, Stephan; Daniel, Werner G; Achenbach, Stephan

    2008-11-01

    The ability of contrast-enhanced CT to detect "late enhancement" in a fashion similar to magnetic resonance imaging has been reported previously. Typical myocardial distribution patterns of "late enhancement" have been described for MRI. The same patterns can be observed in CT imaging, albeit at a lower signal to noise ratio. We report a case of cardiac amyloidosis with a typical pattern of subendocardial, circumferential late enhancement in all four cardiac chambers.

  16. A dual-beam actinic light source for photosynthesis research

    NASA Technical Reports Server (NTRS)

    Margozzi, A. P.; Henderson, M. E.

    1972-01-01

    Simulation of photosynthetic process in plants is accomplished by using two separate and identical optical channels that provide independently adjustable wavelengths (filters), shutter sequencing, and control intensity of illumination. In addition to experiments using electron paramagnetic resonance spectroscopy, system may be applicable to other types of research in photosynthetic field.

  17. Dual nozzle aerodynamic and cooling analysis study

    NASA Technical Reports Server (NTRS)

    Meagher, G. M.

    1981-01-01

    Analytical models to predict performance and operating characteristics of dual nozzle concepts were developed and improved. Aerodynamic models are available to define flow characteristics and bleed requirements for both the dual throat and dual expander concepts. Advanced analytical techniques were utilized to provide quantitative estimates of the bleed flow, boundary layer, and shock effects within dual nozzle engines. Thermal analyses were performed to define cooling requirements for baseline configurations, and special studies of unique dual nozzle cooling problems defined feasible means of achieving adequate cooling.

  18. Dual leadership in a hospital practice.

    PubMed

    Thude, Bettina Ravnborg; Thomsen, Svend Erik; Stenager, Egon; Hollnagel, Erik

    2017-02-06

    Purpose Despite the practice of dual leadership in many organizations, there is relatively little research on the topic. Dual leadership means two leaders share the leadership task and are held jointly accountable for the results of the unit. To better understand how dual leadership works, this study aims to analyse three different dual leadership pairs at a Danish hospital. Furthermore, this study develops a tool to characterize dual leadership teams from each other. Design/methodology/approach This is a qualitative study using semi-structured interviews. Six leaders were interviewed to clarify how dual leadership works in a hospital context. All interviews were transcribed and coded. During coding, focus was on the nine principles found in the literature and another principle was found by looking at the themes that were generic for all six interviews. Findings Results indicate that power balance, personal relations and decision processes are important factors for creating efficient dual leaderships. The study develops a categorizing tool to use for further research or for organizations, to describe and analyse dual leaderships. Originality/value The study describes dual leadership in the hospital context and develops a categorizing tool for being able to distinguish dual leadership teams from each other. It is important to reveal if there are any indicators that can be used for optimising dual leadership teams in the health-care sector and in other organisations.

  19. Offset dual-shaped reflectors for dual chamber compact ranges

    NASA Technical Reports Server (NTRS)

    Galindo-Israel, Victor; Imbriale, William A.; Rengarajan, Sembiam R.; Mittra, Raj

    1991-01-01

    The application of the theory of the synthesis of offset dual-shaped reflectors to the design of compact ranges is examined. The object of the compact range is to provide a uniform plane wave with minimum amplitude and phase ripple over as large a volume as possible for a given size reflector. Ripple can be lowered by reducing the edge diffraction from the reflector producing the plane wave. This has been done either by serrating or rolling the edge. An alternative approach is to use dual offset-shaped reflector synthesis techniques to produce a reflector aperture distribution that is uniform over most of the aperture, but with a Gaussian taper near the edge. This approach can be used together with rolling and/or serration if desirable. The amount of phase and amplitude ripple obtained with two different dual-shaped reflector designs is studied as a function of position in the plane wave zone and reflector size in wavelengths. The amount of both transverse and longitudinal (z-component) cross polarization is studied.

  20. Dual arm master controller development

    NASA Technical Reports Server (NTRS)

    Kuban, D. P.; Perkins, G. S.

    1985-01-01

    The advanced servomanipulator (ASM) slave was designed with an anthropomorphic stance gear/torque tube power drives, and modular construction. These features resulted in increased inertia, friction, and backlash relative to tape driven manipulators. Studies were performed which addressed to human factor design and performance tradeoffs associated with the corresponding master controller best suited for the ASM. The results of these studies, as well as the conceptual design of the dual arm master controller, are presented.

  1. HELIOS dual swept frequency radiometer

    NASA Technical Reports Server (NTRS)

    White, J. R.

    1975-01-01

    The HELIOS dual swept frequency radiometer, used in conjunction with a dipole antenna, was designed to measure electromagnetic radiation in space. An engineering prototype was fabricated and tested on the HELIOS spacecraft. Two prototypes and two flight units were fabricated and three of the four units were integrated into the HELIOS spacecraft. Two sets of ground support equipment were provided for checkout of the radiometer.

  2. Harnessing spectral property of dual wavelength white LED to improve vertical scanning interferometry.

    PubMed

    Chong, Wee Keat; Li, Xiang; Soh, Yeng Chai

    2013-07-01

    Unlike a conventional white light source that emits a continuous and broad spectrum of light, the dual wavelength white light emitting diode (LED) generates white light by mixing blue and yellow lights, so there are two distinct peaks in its intensity spectrum. Prior works had shown that the spectral property of the dual wavelength white LED can affect the vertical scanning interferometry negatively if the spectral effects are not compensated. In this paper, we shall examine this issue by modeling the spectral property and variation of the dual wavelength white LED, followed by investigating its effects on the interference signal of vertical scanning interferometry. Instead of compensating the spectral effects of the dual wavelength white LED, we harness its spectral property to improve the performance of a phase-based height reconstruction algorithm in vertical scanning interferometry.

  3. Determination of the area density and composition of alloy film using dual alpha particle energy loss

    NASA Astrophysics Data System (ADS)

    Ma, Xiaojun; Li, Bo; Gao, Dangzhong; Xu, Jiayun; Tang, Yongjian

    2017-02-01

    A novel method based on dual α-particles energy loss (DAEL) is proposed for measuring the area density and composition of binary alloy films. In order to obtain a dual-energy α-particles source, an ingenious design that utilizes the transmitted α-particles traveling the thin film as a new α-particles source is presented. Using the DAEL technique, the area density and composition of Au/Cu film are determined accurately with an uncertainty of better than 10%. Finally, some measures for improving the combined uncertainty are discussed.

  4. A tunable dual frequency dye laser - dual frequency oscillator design

    NASA Technical Reports Server (NTRS)

    Abury, Y.

    1983-01-01

    The pulsed dye laser offers a tunable oscillator, followed by three amplifiers. It is pumped by a dual frequency Nd:YAG laser. Tuning and spectral width are controlled by a holographic network connected to a high power telescope. The modified two wavelength dye laser allows for absorption lidar techniques for remote sensing of the atmosphere. Line switching is achieved by electrooptical commutation. A feasibility experiment was performed with the original oscillator. A model was then built, and tested with different dyes. After a few modifications were made to improve the conversion efficiency, this oscillator was inserted in the laser to check whether the amplifier stages were correctly adjusted.

  5. Ion source based on the cathodic arc

    DOEpatents

    Sanders, D.M.; Falabella, S.

    1994-02-01

    A cylindrically symmetric arc source to produce a ring of ions which leave the surface of the arc target radially and are reflected by electrostatic fields present in the source to a point of use, such as a part to be coated, is described. An array of electrically isolated rings positioned in the source serves the dual purpose of minimizing bouncing of macroparticles and providing electrical insulation to maximize the electric field gradients within the source. The source also includes a series of baffles which function as a filtering or trapping mechanism for any macroparticles. 3 figures.

  6. Ion source based on the cathodic arc

    DOEpatents

    Sanders, David M.; Falabella, Steven

    1994-01-01

    A cylindrically symmetric arc source to produce a ring of ions which leave the surface of the arc target radially and are reflected by electrostatic fields present in the source to a point of use, such as a part to be coated. An array of electrically isolated rings positioned in the source serves the dual purpose of minimizing bouncing of macroparticles and providing electrical insulation to maximize the electric field gradients within the source. The source also includes a series of baffles which function as a filtering or trapping mechanism for any macroparticles.

  7. NASA Dual Precipitation Radar Arrives at Goddard

    NASA Video Gallery

    The Dual-frequency Precipitation Radar (DPR) built by the Japan Aerospace Exploration Agency (JAXA) for the Global Precipitation Measurement (GPM) mission's Core Observatory arrived on Friday, Marc...

  8. [DEXA (dual-energy x-ray absorptiometry) and DPA (dual photon absorptiometry) in densitometry of the femoral neck: correlation of the measurements of three commercially available instruments].

    PubMed

    Hübsch, P; Schneider, B; Seidl, G; Kalchhauser, G; Klaushofer, K; Popovic, R

    1991-07-01

    The bone mineral density measurements of three different instruments at the femoral head were compared using 12 cadaver specimens. Two of these instruments were operated by x-rays (dual energy x-ray absorptiometry = DEXA), whereas one system was based on a gadolinium source (dual photon absorptiometry = DPA). Although excellent correlation between the measurements was obtained (r greater than 0,9), the measurements of one of the DEXA-instruments were significantly higher than the measurements of the two other systems. We conclude that a comparison of bone mineral density measurements obtained on different densitometry instruments may pose problems. Follow-up examinations should be done on one single densitometry unit.

  9. Dual aperture multispectral Schmidt objective

    NASA Astrophysics Data System (ADS)

    Minott, P. O.

    1984-04-01

    A dual aperture, off-axis catadioptic Schmidt objective is described. It is formed by symmetrically aligning two pairs of Schmidt objectives on opposite sides of a common plane (x,z). Each objective has a spherical primary mirror with a spherical focal plane and center of curvature aligned along an optic axis laterally spaced apart from the common plane. A multiprism beamsplitter with buried dichroic layers and a convex entrance and concave exit surfaces optically concentric to the center of curvature may be positioned at the focal plane. The primary mirrors of each objective may be connected rigidly together and may have equal or unequal focal lengths.

  10. Dual aperture multispectral Schmidt objective

    NASA Technical Reports Server (NTRS)

    Minott, P. O. (Inventor)

    1984-01-01

    A dual aperture, off-axis catadioptic Schmidt objective is described. It is formed by symmetrically aligning two pairs of Schmidt objectives on opposite sides of a common plane (x,z). Each objective has a spherical primary mirror with a spherical focal plane and center of curvature aligned along an optic axis laterally spaced apart from the common plane. A multiprism beamsplitter with buried dichroic layers and a convex entrance and concave exit surfaces optically concentric to the center of curvature may be positioned at the focal plane. The primary mirrors of each objective may be connected rigidly together and may have equal or unequal focal lengths.

  11. Dual intercalating molten electrolyte batteries

    SciTech Connect

    Carlin, R.T.; Long, H.C. De; Fuller, J.; Lauderdale, W.J.; Naughton, T.; Trulove, P.C.; Bahn, C.S.

    1995-12-31

    Dual Intercalating Molten Electrolyte (DIME) electrodes and cells have been examined using a number of low-melting and room-temperature molten salts. A cell with a chloroaluminate melt achieved a cycling efficiency of 85% with a discharge voltage of 2.92 V. Coke-elastomer composite electrodes underwent cation reductive intercalation without experiencing the exfoliation and degradation seen for graphite rods. Theoretical studies for an imidazolium-graphite intercalate predicted the graphite layer spacing expands between 5.18 and 8.01 {angstrom} upon insertion of the imidazolium molecule into the graphite lattice.

  12. Dual laser gyro test program

    NASA Astrophysics Data System (ADS)

    Jones, Malcolm E.; Moore, Kim Eric

    This paper addresses the results of a comparative test evaluation of two similar-sized but otherwise dissimilar ring laser gyroscopes (RLG's). Both units were tested side by side, with the input axes (IA's) parallel, on the same test table. This report describes the rationale and design factors considered important to the test objectives. Emphasis was placed upon the evaluation of the scale factor (SF) linearity, drift rate stability (short term and long term), and derived rate. Conclusions drawn were (1) that dual operation had an observable but insignificant effect on the test results, (2) that the benefits of dual operation outweighed the additional design and analysis efforts required at the outset of the program, and (3) that the performance characteristics of the two test articles were significantly different. The differences between the two test articles (1) led to suggestions which could direct one vendor toward obtaining improved performance and (2) resulted in the creation of a conceptually new method (DELTA TIME-COUNT histogram) for quickly assessing the quality of laser gyros (or any digital sensor device for that matter).

  13. Dual Annual Spawning Races in Atlantic Sturgeon

    PubMed Central

    Balazik, Matthew T.; Musick, John A.

    2015-01-01

    Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus, Acipenseridae) populations in the United States were listed as either endangered or threatened under the Endangered Species Act in 2012. Because of the endangered/threatened status, a better understanding of Atlantic sturgeon life-history behavior and habitat use is important for effective management. It has been widely documented that Atlantic sturgeon reproduction occurs from late winter to early summer, varying clinally with latitude. However, recent data show Atlantic sturgeon also spawn later in the year. The group that spawns later in the year seems to be completely separate from the spring spawning run. Recognition of the later spawning season has drastically modified estimates of the population status of Atlantic sturgeon in Virginia. With the combination of new telemetry data and historical documentation we describe a dual spawning strategy that likely occurs in various degrees along most, if not all, of the Atlantic sturgeon's range. Using new data combined with historical sources, a new spawning strategy emerges which managers and researchers should note when determining the status of Atlantic sturgeon populations and implementing conservation measures. PMID:26020631

  14. Dual annual spawning races in Atlantic sturgeon.

    PubMed

    Balazik, Matthew T; Musick, John A

    2015-01-01

    Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus, Acipenseridae) populations in the United States were listed as either endangered or threatened under the Endangered Species Act in 2012. Because of the endangered/threatened status, a better understanding of Atlantic sturgeon life-history behavior and habitat use is important for effective management. It has been widely documented that Atlantic sturgeon reproduction occurs from late winter to early summer, varying clinally with latitude. However, recent data show Atlantic sturgeon also spawn later in the year. The group that spawns later in the year seems to be completely separate from the spring spawning run. Recognition of the later spawning season has drastically modified estimates of the population status of Atlantic sturgeon in Virginia. With the combination of new telemetry data and historical documentation we describe a dual spawning strategy that likely occurs in various degrees along most, if not all, of the Atlantic sturgeon's range. Using new data combined with historical sources, a new spawning strategy emerges which managers and researchers should note when determining the status of Atlantic sturgeon populations and implementing conservation measures.

  15. Dual-domain lateral shearing interferometer

    DOEpatents

    Naulleau, Patrick P.; Goldberg, Kenneth Alan

    2004-03-16

    The phase-shifting point diffraction interferometer (PS/PDI) was developed to address the problem of at-wavelength metrology of extreme ultraviolet (EUV) optical systems. Although extremely accurate, the fact that the PS/PDI is limited to use with coherent EUV sources, such as undulator radiation, is a drawback for its widespread use. An alternative to the PS/PDI, with relaxed coherence requirements, is lateral shearing interferometry (LSI). The use of a cross-grating, carrier-frequency configuration to characterize a large-field 4.times.-reduction EUV lithography optic is demonstrated. The results obtained are directly compared with PS/PDI measurements. A defocused implementation of the lateral shearing interferometer in which an image-plane filter allows both phase-shifting and Fourier wavefront recovery. The two wavefront recovery methods can be combined in a dual-domain technique providing suppression of noise added by self-interference of high-frequency components in the test-optic wavefront.

  16. Health risks related to dual use of cigarettes and snus - a systematic review.

    PubMed

    Lee, Peter N

    2014-06-01

    Reviews show that using snus (Swedish-type moist snuff) is much safer than smoking, with no increased risk from snus of cancer or circulatory disease yet demonstrated, but have not investigated possible health effects from dual use of cigarettes and snus. This review considers studies where health risks can be compared in dual users, those who only use snus or only smoke, and those who use neither product. The interaction RR, the ratio of RRs associated with snus use in smokers and in non-smokers, was used to test for special effects of dual use. Of 51 interaction RRs presented, only one (for gestational hypertension in a study based on the Swedish Medical Register) was significantly (p<0.05) above 1.0, and RRs below 1.0 were commoner, perhaps as cigarette consumption is lower in dual users than those who only smoke. Dual users more often initiate tobacco use with cigarettes than snus. Dual use is much commoner in adolescents than adults, possibly because many tobacco users try both products, eventually settling on one. Epidemiological evidence from various sources, though suffering from weaknesses, consistently suggests concomitant snus use increases smoking quit rates, and aligns with evidence from RCTs using snus to aid smoking cessation.

  17. Support Networks of Dual Career Couples.

    ERIC Educational Resources Information Center

    Lloyd, Sally A.; And Others

    Although social networks play an important role in supporting families under stress, there is some evidence that families living a stressful dual career life style may have limited network resources. To describe support networks of dual career couples and to examine the relationship between the supportiveness of the network and satisfaction with…

  18. Dual mode nuclear rocket system applications.

    NASA Technical Reports Server (NTRS)

    Boretz, J. E.; Bell, J. M.; Plebuch, R. K.; Priest, C. C.

    1972-01-01

    Mission areas where the dual-mode nuclear rocket system is superior to nondual-mode systems are demonstrated. It is shown that the dual-mode system is competitive with the nondual-mode system even for those specific missions and particular payload configurations where it does not have a clear-cut advantage.

  19. 7 CFR 247.19 - Dual participation.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 4 2012-01-01 2012-01-01 false Dual participation. 247.19 Section 247.19 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE CHILD NUTRITION PROGRAMS COMMODITY SUPPLEMENTAL FOOD PROGRAM § 247.19 Dual participation. (a) What...

  20. 7 CFR 247.19 - Dual participation.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 4 2014-01-01 2014-01-01 false Dual participation. 247.19 Section 247.19 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE CHILD NUTRITION PROGRAMS COMMODITY SUPPLEMENTAL FOOD PROGRAM § 247.19 Dual participation. (a) What...

  1. 7 CFR 247.19 - Dual participation.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 4 2013-01-01 2013-01-01 false Dual participation. 247.19 Section 247.19 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE CHILD NUTRITION PROGRAMS COMMODITY SUPPLEMENTAL FOOD PROGRAM § 247.19 Dual participation. (a) What...

  2. Dual Learning Processes in Interactive Skill Acquisition

    ERIC Educational Resources Information Center

    Fu, Wai-Tat; Anderson, John R.

    2008-01-01

    Acquisition of interactive skills involves the use of internal and external cues. Experiment 1 showed that when actions were interdependent, learning was effective with and without external cues in the single-task condition but was effective only with the presence of external cues in the dual-task condition. In the dual-task condition, actions…

  3. Learning from the Past: Dual Credit

    ERIC Educational Resources Information Center

    Mansell, Nicole; Justice, Madeline

    2014-01-01

    This study involved identifying, categorizing, and comparing critical incidents related to qualifying dual credit high school students' decisions to enroll or not to enroll in dual credit coursework in either a traditional or early college high school. The purpose of the study was (a) to identify the reasons qualifying students decide to enroll in…

  4. A Dual-Polarity Impulse Radiating Antenna

    NASA Astrophysics Data System (ADS)

    Bowen, L. H.; Farr, E. G.; Lawry, D. I.

    Dual polarity Impulse Radiating Antennas (IRA's) may be useful in a variety of applications. The dual-polarity IRA described here has an impendence mismatch for each polarity at the focus of the reflector. In spite of this mismatch the antenna characteristics are quite good up to 10 GHz for applications where reflections within the system are not of great importance.

  5. Dual wound dc brush motor gearhead

    NASA Technical Reports Server (NTRS)

    Henson, Barrie W.

    1986-01-01

    The design requirements, the design, development tests and problems, the qualification and life test and the findings of the strip examination of a dual wound DC brushed motor gearhead are described. It is the only space qualified dual wound dc brushed motor gearhead in Europe.

  6. 7 CFR 7.17 - Dual office.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Dual office. 7.17 Section 7.17 Agriculture Office of the Secretary of Agriculture SELECTION AND FUNCTIONS OF AGRICULTURAL STABILIZATION AND CONSERVATION STATE, COUNTY AND COMMUNITY COMMITTEES § 7.17 Dual office. (a) County committee membership. A member...

  7. Departmental Issues in Dual-Academic Marriages.

    ERIC Educational Resources Information Center

    Barbee, Anita P.; Cunningham, Michael R.

    This paper discusses issues pertaining to the recruitment and hiring of dual-career academic couples by universities and psychology departments. Studies have shown that both husbands and wives in dual psychologist couples are more productive in number of publications, paper presentations, and grants awarded than their single counterparts, yet many…

  8. What Makes Dual-Career Marriages Tick?

    ERIC Educational Resources Information Center

    Gilbert, Lucia Albino

    A dual-career family is a family in which both spouses are committed to occupational work and to a family life together and support each other's desires to combine roles that traditionally were viewed as incompatible. Male socialization in the areas of entitlement, dependency, and nurturance can cause problems for men in dual-career marriages. In…

  9. College Course Grades for Dual Enrollment Students

    ERIC Educational Resources Information Center

    Crouse, Jill D.; Allen, Jeff

    2014-01-01

    This study compared college course grade outcomes, both during and after high school, of dual-enrollment students to those of traditional students. The study was based on a large, multiyear sample of Iowa high school and community college students. The results showed that while in high school, dual-enrollment students consistently outperformed…

  10. Dual Career Couples: New Perspectives in Counseling.

    ERIC Educational Resources Information Center

    Stoltz-Loike, Marian

    This book, written for counselors and other mental health professionals, outlines the stresses and challenges dual career couples face, as well as plans for helping dual career couples learn negotiation, communicaiton, and conflict resolution skills. The book's 12 chapters are organized in 3 parts. Part 1 (chapters 1 to 4), reviews the literature…

  11. Dual Protection and Dual Methods in Women Living with HIV: The Brazilian Context

    PubMed Central

    Barbosa, Regina María; Pinho, Adriana de Araujo

    2013-01-01

    The cooccurrence of HIV and unintended pregnancy has prompted a body of work on dual protection, the simultaneous protection against HIV and unintended pregnancy. This study examines dual protection and dual methods as a risk-reduction strategy for women living with HIV. Data are from a cross-sectional sample of HIV-positive women attended in Specialized STI/AIDS Public Health Service Clinics in 13 municipalities from all five regions of Brazil 2003-2004 (N = 834). Descriptive techniques and logistic regression were used to examine dual protection among women living with HIV. We expand the definition of dual protection to include consistent condom use and reversible/irreversible contraceptive methods, we test the dual methods hypothesis that women who use dual methods will use condoms less consistently than women who use only condoms, and we identify predictors of dual protection. Dual protection is common in our sample. Women who use dual methods have lower odds of consistent condom use than women who only use condoms. Among dual method users, we find that women who use an irreversible method use condoms more consistently than women who use a reversible method. Women on ART and with an HIV-serodiscordant partner have greater odds of consistent condom use than their counterparts. PMID:26316959

  12. Caustic Singularities Of High-Gain, Dual-Shaped Reflectors

    NASA Technical Reports Server (NTRS)

    Galindo, Victor; Veruttipong, Thavath W.; Imbriale, William A.; Rengarajan, Sambiam

    1991-01-01

    Report presents study of some sources of error in analysis, by geometric theory of diffraction (GTD), of performance of high-gain, dual-shaped antenna reflector. Study probes into underlying analytic causes of singularity, with view toward devising and testing practical methods to avoid problems caused by singularity. Hybrid physical optics (PO) approach used to study near-field spillover or noise-temperature characteristics of high-gain relector antenna efficiently and accurately. Report illustrates this approach and underlying principles by presenting numerical results, for both offset and symmetrical reflector systems, computed by GTD, PO, and PO/GO methods.

  13. Modelling and Analysis of Dual-Stator Induction Motors

    NASA Astrophysics Data System (ADS)

    Razik, Hubert; Rezzoug, Abderrezak; Hadiouche, Djafar

    In this paper, the analysis and the modelling of a Dual-Stator Induction Motor (DSIM) are presented. In particular, the effects of the shift angle between its three-phase windings are studied. A complex steady state model is first established in order to analyse its harmonic behavior when it is supplied by a non-sinusoidal voltage source. Then, a new transformation matrix is proposed to develop a suitable dynamic model. In both cases, the study is made using an arbitrary shift angle. Simulation results of its PWM control are also presented and compared in order to confirm our theoretical observations.

  14. A tandem-based compact dual-energy gamma generator.

    PubMed

    Persaud, A; Kwan, J W; Leitner, M; Leung, K-N; Ludewigt, B; Tanaka, N; Waldron, W; Wilde, S; Antolak, A J; Morse, D H; Raber, T

    2010-02-01

    A dual-energy tandem-type gamma generator has been developed at E. O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications. Both positively charged ions and atoms of hydrogen are created from negative ions via a gas stripper. In this paper, we show first results of the working tandem-based gamma generator and that a gas stripper can be utilized in a compact source design. Preliminary results of monoenergetic gamma production are shown.

  15. Dual-Band Magnetic Loop Antenna with Monopolar Radiation Using Slot-Loaded Composite Right/Left-Handed Structures

    NASA Astrophysics Data System (ADS)

    Pyo, Seongmin; Lee, Min-Jae; Lee, Kyoung-Joo; Kim, Young-Sik

    A novel dual-band magnetic loop antenna is proposed using slot-loaded composite right/left-handed (SL-CRLH) structures. Since each radiating element consists of a symmetrically-array of unit-cells, a dual-band magnetic loop source is obtained with unchanged beam patterns. Simulations and measurements show its good radiation performance with monopole-like radiation patterns in both operating bands.

  16. Isolating the Neural Mechanisms of Interference During Continuous Multisensory Dual-task Performance

    DTIC Science & Technology

    2014-01-01

    sion accuracy in each task, the signal detection theory sensitivity measure of d0 was used (Macmillan & Creelman , 1991; Green & Swets, 1966). First...J. (1998). Sources of dual-task interference: Evidence from human electrophysiology. Psychological Science, 9, 223–227. Macmillan, N. A., & Creelman

  17. Mitigating Multipath Bias Using a Dual-Polarization Antenna: Theoretical Performance, Algorithm Design, and Simulation

    PubMed Central

    Xie, Lin; Cui, Xiaowei; Zhao, Sihao; Lu, Mingquan

    2017-01-01

    It is well known that multipath effect remains a dominant error source that affects the positioning accuracy of Global Navigation Satellite System (GNSS) receivers. Significant efforts have been made by researchers and receiver manufacturers to mitigate multipath error in the past decades. Recently, a multipath mitigation technique using dual-polarization antennas has become a research hotspot for it provides another degree of freedom to distinguish the line-of-sight (LOS) signal from the LOS and multipath composite signal without extensively increasing the complexity of the receiver. Numbers of multipath mitigation techniques using dual-polarization antennas have been proposed and all of them report performance improvement over the single-polarization methods. However, due to the unpredictability of multipath, multipath mitigation techniques based on dual-polarization are not always effective while few studies discuss the condition under which the multipath mitigation using a dual-polarization antenna can outperform that using a single-polarization antenna, which is a fundamental question for dual-polarization multipath mitigation (DPMM) and the design of multipath mitigation algorithms. In this paper we analyze the characteristics of the signal received by a dual-polarization antenna and use the maximum likelihood estimation (MLE) to assess the theoretical performance of DPMM in different received signal cases. Based on the assessment we answer this fundamental question and find the dual-polarization antenna’s capability in mitigating short delay multipath—the most challenging one among all types of multipath for the majority of the multipath mitigation techniques. Considering these effective conditions, we propose a dual-polarization sequential iterative maximum likelihood estimation (DP-SIMLE) algorithm for DPMM. The simulation results verify our theory and show superior performance of the proposed DP-SIMLE algorithm over the traditional one using only an

  18. Mitigating Multipath Bias Using a Dual-Polarization Antenna: Theoretical Performance, Algorithm Design, and Simulation.

    PubMed

    Xie, Lin; Cui, Xiaowei; Zhao, Sihao; Lu, Mingquan

    2017-02-13

    It is well known that multipath effect remains a dominant error source that affects the positioning accuracy of Global Navigation Satellite System (GNSS) receivers. Significant efforts have been made by researchers and receiver manufacturers to mitigate multipath error in the past decades. Recently, a multipath mitigation technique using dual-polarization antennas has become a research hotspot for it provides another degree of freedom to distinguish the line-of-sight (LOS) signal from the LOS and multipath composite signal without extensively increasing the complexity of the receiver. Numbers of multipath mitigation techniques using dual-polarization antennas have been proposed and all of them report performance improvement over the single-polarization methods. However, due to the unpredictability of multipath, multipath mitigation techniques based on dual-polarization are not always effective while few studies discuss the condition under which the multipath mitigation using a dual-polarization antenna can outperform that using a single-polarization antenna, which is a fundamental question for dual-polarization multipath mitigation (DPMM) and the design of multipath mitigation algorithms. In this paper we analyze the characteristics of the signal received by a dual-polarization antenna and use the maximum likelihood estimation (MLE) to assess the theoretical performance of DPMM in different received signal cases. Based on the assessment we answer this fundamental question and find the dual-polarization antenna's capability in mitigating short delay multipath-the most challenging one among all types of multipath for the majority of the multipath mitigation techniques. Considering these effective conditions, we propose a dual-polarization sequential iterative maximum likelihood estimation (DP-SIMLE) algorithm for DPMM. The simulation results verify our theory and show superior performance of the proposed DP-SIMLE algorithm over the traditional one using only an RHCP

  19. The Cortical Organization of Speech Processing: Feedback Control and Predictive Coding the Context of a Dual-Stream Model

    ERIC Educational Resources Information Center

    Hickok, Gregory

    2012-01-01

    Speech recognition is an active process that involves some form of predictive coding. This statement is relatively uncontroversial. What is less clear is the source of the prediction. The dual-stream model of speech processing suggests that there are two possible sources of predictive coding in speech perception: the motor speech system and the…

  20. Self-dual MacDowell-Mansouri gravity coupled to self-dual Yang-Mills fields

    NASA Astrophysics Data System (ADS)

    Chee, G. Y.

    2000-09-01

    A unified action for self-dual MacDowell-Mansouri gravity and Yang-Mills fields is proposed. The dual operation acting on the curvature and the self-dual and anti-self-dual decomposition are performed with respect to spacetime indices rather than internal indices, which makes the action simpler than the one given by Nieto and Socorro. In the new action the (anti-)self-dual Yang-Mills curvature couples only to the (anti-)self-dual curvature of the spacetime and then the self-dual and the anti-self-dual parts of the action are separated completely.

  1. Dual-Materials Dispersion Apparatus

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Experiments to seek solutions for a range of biomedical issues are at the heart of several investigations that will be hosted by the Commercial Instrumentation Technology Associates (ITA), Inc. Biomedical Experiments (CIBX-2) payload. CIBX-2 is unique, encompassing more than 20 separate experiments including cancer research, commercial experiments, and student hands-on experiments from 10 schools as part of ITA's ongoing University Among the Stars program. This drawing depicts a cross-section of a set of Dual-Materials Dispersion Apparatus (DMDA) specimen wells, one of which can include a reverse osmosis membrane to dewater a protein solution and thus cause crystallization. Depending on individual needs, two or three wells may be used, the membrane may be absent, or other proprietary enhancements may be present. The experiments are sponsored by NASA's Space Product Development Program (SPD).

  2. Shock sensing dual mode warhead

    SciTech Connect

    Shamblen, M.; Walchak, M.T.; Richmond, L.

    1980-12-31

    A shock sensing dual mode warhead is provided for use against both soft and hard targets and is capable of sensing which type of target has been struck. The warhead comprises a casing made of a ductile material containing an explosive charge and a fuze assembly. The ductile warhead casing will mushroom upon striking a hard target while still confining the explosive. Proper ductility and confinement are necessary for fuze shock sensing. The fuze assembly contains a pair of parallel firing trains, one initiated only by dynamic pressure caused high impact deceleration and one initiated by low impact deceleration. The firing train actuated by high impact deceleration senses dynamic pressure transmitted, during deformation of the warhead, through the explosive filler which is employed as a fuzing signature. The firing train actuated by low impact deceleration contains a pyrotechnic delay to allow penetration of soft targets.

  3. Stable dual-wavelength microlaser controlled by the output mirror tilt angle

    NASA Astrophysics Data System (ADS)

    Pallas, Florent; Herault, Emilie; Zhou, Jie; Roux, Jean-Francois; Vitrant, Guy

    2011-12-01

    A continuous-wave dual-wavelength solid-state microlaser is presented and a technique for regulating the gain competition between the two wavelengths is proposed, based on the angular tilt of the laser cavity output mirror. Laser behavior is studied and balanced dual-wavelength emission is obtained with output power levels as high as 200 mW for 2 W pump power. Sum frequency mixing is demonstrated making the source promising for Terahertz generation in the 0.5-0.7 THz range through difference frequency generation.

  4. Mid-infrared dual-comb spectroscopy with an optical parametric oscillator.

    PubMed

    Zhang, Zhaowei; Gardiner, Tom; Reid, Derryck T

    2013-08-15

    We present the first implementation of mid-infrared dual-comb spectroscopy with an optical parametric oscillator. Methane absorption spectroscopy was demonstrated with a resolution of 0.2 cm(-1) (5 GHz) at an acquisition time of ~10.4 ms over a spectral coverage at 2900-3050 cm(-1). The average power from each individual mid-infrared comb line was ~1 μW, representing a power level much greater than typical difference-frequency-generation sources. Mid-infrared dual-comb spectroscopy opens up unique opportunities to perform broadband spectroscopic measurements with high resolution, high requisition rate, and high detection sensitivity.

  5. The gravity duals of modular Hamiltonians

    NASA Astrophysics Data System (ADS)

    Jafferis, Daniel L.; Suh, S. Josephine

    2016-09-01

    In this work, we investigate modular Hamiltonians defined with respect to arbitrary spatial regions in quantum field theory states which have semi-classical gravity duals. We find prescriptions in the gravity dual for calculating the action of the modular Hamiltonian on its defining state, including its dual metric, and also on small excitations around the state. Curiously, use of the covariant holographic entanglement entropy formula leads us to the conclusion that the modular Hamiltonian, which in the quantum field theory acts only in the causal completion of the region, does not commute with bulk operators whose entire gauge-invariant description is space-like to the causal completion of the region.

  6. Revisiting impressions using dual-arch trays.

    PubMed

    Small, Bruce W

    2012-01-01

    Making routine perfect impressions is the goal of any restorative dentist. Using dual-arch trays is an easy, repeatable way to accomplish that goal, as long as each step is done before the next and each step is performed perfectly. This column reviewed several articles that support the metal dual-arch concept and provided some clinical tips that might help restorative dentists. The dual-arch technique does have its limits and is meant for one or two teeth in a quadrant when there are other teeth to occlude with. Also, if the case involves anterior guidance, a full-arch impression maybe advisable.

  7. Dual-Use Review and the IRB.

    PubMed

    Resnik, David B

    2010-01-01

    Given the growing threat of the misuse of biomedical research by terrorists or others, institutional review boards (IRBs) are likely to encounter research protocols that raise dual-use issues. While IRBs should be informed about these issues and should be prepared to address them, they should not be burdened with the responsibility of conducting their own dual-use review. A dual-use committee (DUC), institutional biosafety committee (IBC), or other committee should handle this task and convey its findings and recommendations to institutional officials.

  8. Dual of big bang and big crunch

    SciTech Connect

    Bak, Dongsu

    2007-01-15

    Starting from the Janus solution and its gauge theory dual, we obtain the dual gauge theory description of the cosmological solution by the procedure of double analytic continuation. The coupling is driven either to zero or to infinity at the big-bang and big-crunch singularities, which are shown to be related by the S-duality symmetry. In the dual Yang-Mills theory description, these are nonsingular as the coupling goes to zero in the N=4 super Yang-Mills theory. The cosmological singularities simply signal the failure of the supergravity description of the full type IIB superstring theory.

  9. Low-Profile, Dual-Wavelength, Dual-Polarized Antenna

    NASA Technical Reports Server (NTRS)

    Carswell, James R.

    2010-01-01

    A single-aperture, low-profile antenna design has been developed that supports dual-polarization and simultaneous operation at two wavelengths. It realizes multiple beams in the elevation plane, and supports radiometric, radar, and conical scanning applications. This antenna consists of multiple azimuth sticks, with each stick being a multilayer, hybrid design. Each stick forms the h-plane pattern of the C and Ku-band vertically and horizontally polarized antenna beams. By combining several azimuth sticks together, the elevation beam is formed. With a separate transceiver for each stick, the transmit phase and amplitude of each stick can be controlled to synthesize a beam at a specific incidence angle and to realize a particular side-lobe pattern. By changing the transmit phase distribution through the transceivers, the transmit antenna beam can be steered to different incidence angles. By controlling the amplitude distribution, different side lobe patterns and efficiencies can be realized. The receive beams are formed using digital beam synthesis techniques, resulting in very little loss in the receive path, thus enabling a very-low loss receive antenna to support passive measurements.

  10. Nonpoint Sources.

    ERIC Educational Resources Information Center

    Browne, F. X.

    1978-01-01

    Presented a literature review of nonpoint source effects on water quality and pollution covering: (1) water quality effects; (2) watershed studies; (3) nonpoint source models; and nonpoint source controls. A list of 122 references published in 1976 and 1977 is also presented. (HM)

  11. A Single-Probe-Beam, Dual-Frequency Plasma Polarimeter

    NASA Astrophysics Data System (ADS)

    Munro, Blair; Hicks, Nathaniel

    2016-10-01

    A plasma polarimeter instrument is conceived that comprises a single microwave probe beam alternating between two discrete frequencies. The method is similar to a double-heterodyne approach proposed earlier, but reduces system complexity and cost by avoiding a frequency-swept source. The instrument uses a single detector per beamline. Initial synthetic diagnostic testing of the instrument design is presented, and the prospects for further cost and space saving by way of additive manufacturing of instrument quasi-optical components are considered. A test bench setup for initial testing of the dual-frequency source and optical path is described, as is the plan for magnetized plasma measurements in a new plasma laboratory facility at the University of Alaska Anchorage. Supported by UAA Elizabeth Tower Endowment and Complex Systems Group.

  12. A dual-modal retinal imaging system with adaptive optics

    PubMed Central

    Meadway, Alexander; Girkin, Christopher A.; Zhang, Yuhua

    2013-01-01

    An adaptive optics scanning laser ophthalmoscope (AO-SLO) is adapted to provide optical coherence tomography (OCT) imaging. The AO-SLO function is unchanged. The system uses the same light source, scanning optics, and adaptive optics in both imaging modes. The result is a dual-modal system that can acquire retinal images in both en face and cross-section planes at the single cell level. A new spectral shaping method is developed to reduce the large sidelobes in the coherence profile of the OCT imaging when a non-ideal source is used with a minimal introduction of noise. The technique uses a combination of two existing digital techniques. The thickness and position of the traditionally named inner segment/outer segment junction are measured from individual photoreceptors. In-vivo images of healthy and diseased human retinas are demonstrated. PMID:24514529

  13. Dual current readout for precision plating

    NASA Technical Reports Server (NTRS)

    Iceland, W. F.

    1970-01-01

    Bistable amplifier prevents damage in the low range circuitry of a dual scale ammeter. It senses the current and switches automatically to the high range circuitry as the current rises above a preset level.

  14. Dual Diagnosis: Substance Abuse and Mental Illness

    MedlinePlus

    ... Dissociative Disorders Eating Disorders Obsessive-Compulsive Disorder Posttraumatic Stress Disorder Schizoaffective Disorder Schizophrenia Related Conditions Anosognosia Dual Diagnosis Psychosis Self-harm Sleep Disorders Suicide About Us Where We Stand on Public Policy ...

  15. Dual control vibration tests of flight hardware

    NASA Astrophysics Data System (ADS)

    Scharton, Terry D.

    A vibration retest of a spacecraft flight instrument, the Mars Observer Camera (MOC), was conducted using extremal dual control to automatically limit the shaker force and notch the shaker acceleration at resonances. This was the first application of extremal dual control with flight hardware at JPL. The retest was successful in that the environment was representative of flight plus some margin, the instrument survived without any structural or performance degradation, and the force limiting worked very well. The test set-up, force limiting procedure, and test results are described herein. It is concluded that dual control should be utilized when there is a concern about overtesting in hard-base-drive tests and the instrumentation for force measurement and control is available. Recommendations for improving the implementation of dual control are provided as a result of this first experience.

  16. Dual Enrollment Participation from the Student Perspective

    ERIC Educational Resources Information Center

    Kanny, M. Allison

    2015-01-01

    This chapter examines the experiences of five high school students previously enrolled in dual enrollment courses, and discusses the perceived benefits and disadvantages of these experiences from the student perspective.

  17. Dual photochemical replenisher system reduces chemical losses

    NASA Technical Reports Server (NTRS)

    Kolber, J. M.

    1967-01-01

    Dual replenisher system reduces chemical losses and maintains optimum solution concentration during long nonprocessing cycles of photo processing machines. Using a single 3-position switch and solenoid control valves, the system provides instantaneous flow control to each processing tank.

  18. Lunar Surface Operations with Dual Rovers

    NASA Technical Reports Server (NTRS)

    Horz, Friedrich; Lofgren, Gary E.; Eppler, Dean E.; Ming, Douglas

    2010-01-01

    Lunar Electric Rovers (LER) are currently being developed that are substantially more capable than the Apollo vehicle (LRN ,"). Unlike the LRV, the new LERs provide a pressurized cabin that serves as short-sleeve environment for the crew of two, including sleeping accommodations and other provisions that allow for long tern stays, possibly up to 60 days, on the hear surface, without the need to replenish consumables from some outside source, such as a lander or outpost. As a consequence, significantly larger regions may be explored in the future and traverse distances may be measured in a few hundred kilometers (1, 2). However, crew safety remains an overriding concern, and methods other than "walk back", the major operational constraint of all Apollo traverses, must be implemented to assure -at any time- the safe return of the crew to the lander or outpost. This then causes current Constellation plans to envision long-tern traverses to be conducted with 2 LERs exclusively, each carrying a crew of two: in case one rover fails, the other will rescue the stranded crew and return all 4 astronauts in a single LER to base camp. Recent Desert Research and Technology Studies (DRATS) analog field tests simulated a continuous 14 day traverse (3), covering some 135 km, and included a rescue operation that transferred the crew and diverse consumables from one LER to another these successful tests add substantial realism to the development of long-term, dual rover operations. The simultaneous utilization of 2 LERs is of course totally unlike Apollo and raises interesting issues regarding science productivity and mission operations, the thrust of this note.

  19. Room-temperature dual-wavelength lasing from single-nanoribbon lateral heterostructures.

    PubMed

    Xu, Jinyou; Ma, Liang; Guo, Pengfei; Zhuang, Xiujuan; Zhu, Xiaoli; Hu, Wei; Duan, Xiangfeng; Pan, Anlian

    2012-08-01

    Nanoscale dual-wavelength lasers are attractive for their potential applications in highly integrated photonic devices. Here we report the growth of nanoribbon lateral heterostructures made of a CdS(x)Se(1-x) central region with epitaxial CdS lateral sides using a multistep thermal evaporation route with a moving source. Under laser excitation, the emission of these ribbons indicates sandwich-like structures along the width direction, with characteristic red emission in the center and green emission at both edges. More importantly, dual-wavelength lasing with tunable wavelengths is demonstrated at room temperature based on these single-nanoribbon heterostructures for the first time. These achievements represent a significant advance in designing nanoscale dual-wavelength lasers and have the potential to open up new and exciting opportunities for diverse applications in integrated photonics, optoelectronics, and sensing.

  20. Heterogeneously integrated III-V/silicon dual-mode distributed feedback laser array for terahertz generation.

    PubMed

    Shao, Haifeng; Keyvaninia, Shahram; Vanwolleghem, Mathias; Ducournau, Guillaume; Jiang, Xiaoqing; Morthier, Geert; Lampin, Jean-Francois; Roelkens, Gunther

    2014-11-15

    We demonstrate an integrated distributed feedback (DFB) laser array as a dual-wavelength source for narrowband terahertz (THz) generation. The laser array is composed of four heterogeneously integrated III-V-on-silicon DFB lasers with different lengths enabling dual-mode lasing tolerant to process variations, bias fluctuations, and ambient temperature variations. By optical heterodyning the two modes emitted by the dual-wavelength DFB laser in the laser array using a THz photomixer composed of an uni-traveling carrier photodiode (UTC-PD), a narrow and stable carrier signal with a frequency of 0.357 THz is generated. The central operating frequency and the emitted terahertz wave linewidth are analyzed, along with their dependency on the bias current applied to the laser diode and ambient temperature.

  1. High-power dual-wavelength laser with disordered Nd:CNGG crystals.

    PubMed

    Yu, Haohai; Zhang, Huaijin; Wang, Zhengping; Wang, Jiyang; Yu, Yonggui; Shi, Zibin; Zhang, Xingyu; Jiang, Minhua

    2009-01-15

    We demonstrate the high-power dual-wavelength laser output with disordered Nd:CNGG laser crystals. Continuous-wave output power of 4.03 W was obtained under the incident pump power of 15.62 W. In the passively Q-switched operation, the shortest pulse width, largest pulse energy, and highest peak power were achieved to be 12.9 ns, 173.16 microJ, and 12.3 kW, respectively, with Cr(4+):YAG crystals as the saturable absorbers. By spectral analysis, the output lasers were found to have dual wavelengths. We believed that the passively Q-switched dual-wavelength laser should be possible to be used as a source for the generation of terahertz radiation.

  2. Dual-channel near-field control by polarizations using isotropic and inhomogeneous metasurface

    PubMed Central

    Wan, Xiang; Cai, Ben Geng; Li, Yun Bo; Cui, Tie Jun

    2015-01-01

    We propose a method for dual-channel near-field manipulations by designing isotropic but inhomogeneous metasurfaces. As example, we present a dual-channel near-field focusing metasurface device. When the device is driven by surface waves from different channels on the metasurface, the near fields will be focused at the same spatial point with different polarizations. Conversely, if a linearly polarized source is radiated at the spatial focal point, different channels will be evoked on the metasurface controlled by polarization. We fabricated and measured the metasurface device in the microwave frequency. Well agreements between the simulation and measurement results are observed. The proposed method exhibits great flexibility in controlling the surface waves and spatial waves simultaneously. It is expected that the proposed method and dual-channel device will facilitate the manipulation of near electromagnetic or optical waves in different frequency regimes. PMID:26527420

  3. Algebraic dual-energy magnetic analysis with application to variable reluctance motor design

    SciTech Connect

    Tolikas, M.; Lang, J.H.; Kirtley, J.L. Jr.

    1995-12-31

    The dual-energy method has been successfully employed in the calculation of static resistances, capacitances and inductances, yielding fast and accurate solutions. Two different directions can be followed in applying the method, one is the more widely known method of tubes and slices, the other is the algebraic approach and is explored further in this paper. The present literature on the algebraic dual-energy method involves trivial examples with boundaries, boundary conditions and source distributions that are easily handled. However, the geometry of the variable reluctance motor at the unaligned position, the dominating curvatures characterizing its electromagnetic field distribution and the presence of a large number of boundary conditions arising at the steel boundaries, provide a challenging exercise in the application, behavior and effectiveness of the dual-energy method in a realistic framework.

  4. Truncated Dual-Cap Nucleation Site Development

    NASA Technical Reports Server (NTRS)

    Matson, Douglas M.; Sander, Paul J.

    2012-01-01

    During heterogeneous nucleation within a metastable mushy-zone, several geometries for nucleation site development must be considered. Traditional spherical dual cap and crevice models are compared to a truncated dual cap to determine the activation energy and critical cluster growth kinetics in ternary Fe-Cr-Ni steel alloys. Results of activation energy results indicate that nucleation is more probable at grain boundaries within the solid than at the solid-liquid interface.

  5. On the manipulability of dual cooperative robots

    NASA Technical Reports Server (NTRS)

    Chiacchio, P.; Chiaverini, S.; Sciavicco, L.; Siciliano, B.

    1989-01-01

    The definition of manipulability ellipsoids for dual robot systems is given. A suitable kineto-static formulation for dual cooperative robots is adopted which allows for a global task space description of external and internal forces, and relative velocities. The well known concepts of force and velocity manipulability ellipsoids for a single robot are formally extended and the contributions of the two single robots to the cooperative system ellipsoids are illustrated. Duality properties are discussed. A practical case study is developed.

  6. Dual-Compartment Inflatable Suitlock

    NASA Technical Reports Server (NTRS)

    Howe, Scott; Kennedy, Kriss J.; Guirgis, Peggy L.

    2012-01-01

    A paper discusses a dual-compartment inflatable suitlock (DCIS) for Extra - vehicular Activity (EVA) that will allow for dust control, suit maintenance, and efficient EVA egress/ingress. The expandable (inflatable technologies) aspect of the design will allow the unit to stow in a compact package for transport. The DCIS consists of three hard, in line bulkheads, separating two cylindrical membrane-walled compartments. The inner bulkhead can be fitted with a variety of hatch types, docking flanges, and mating hardware, such as the common berthing mechanism (CBM), for the purpose of mating with vehicles, habitats, and other pressurized modules. The inner bulkhead and center bulkhead function as the end walls of the inner compartment, which, during operations, would stay pressurized, either matching the pressure of the habitat or acting as a lower-pressure transitional volume. The suited crewmember can quickly don a suit, and egress the suitlock without waiting for the compartment to depressurize. The outer compartment can be pressurized infrequently, when a long dwell time is expected prior to the next EVA, or during off-nominal suit maintenance tasks, allowing shirtsleeve inspections and maintenance of the space suits. The outer bulkhead has a pressure-assisted hatch door that stays open and stowed routinely, but can be closed for suit maintenance and pressurization as needed.

  7. ISIFC - dual Biomedical Engineering School.

    PubMed

    Butterlin, Nadia; Soto-Romero, Georges; Duffaud, Jacques; Blagosklonov, Oleg

    2007-01-01

    The Superior Institute for Biomedical Engineering (ISIFC), created in 2001, is part of the Franche-Comté University and is accredited by the French Ministry of National Education. Its originality lies in its innovative course of studies, which trains engineers in the scientific and medical fields to get both competencies. The Institute therefore collaborates with the University Hospital Centre of Besançon (CHU), biomedical companies and National Research Centres (CNRS and INSERM). The dual expertise trainees will have acquired at the end of their 3 years course covers medical and biological skills, scientific and Technical expertises. ISIFC engineers answer to manufacturer needs for skilled scientific and technical staff in instrumentation and techniques adapted to diagnosis, therapeutics and medical control, as well as the needs of potential users for biomedical devices, whether they are doctors, hospital staff, patients, laboratories, etc... Both the skills and the knowledge acquired by an ISIFC engineer will enable him/her to fulfil functions of study, research and development in the industrial sector.

  8. Dual Brushless Resolver Rate Sensor

    NASA Technical Reports Server (NTRS)

    Howard, David E. (Inventor)

    1997-01-01

    A resolver rate sensor is disclosed in which dual brushless resolvers are mechanically coupled to the same output shaft. Diverse inputs are provided to each resolver by providing the first resolver with a DC input and the second resolver with an AC sinusoidal input. A trigonometric identity in which the sum of the squares of the sin and cosine components equal one is used to advantage in providing a sensor of increased accuracy. The first resolver may have a fixed or variable DC input to permit dynamic adjustment of resolver sensitivity thus permitting a wide range of coverage. In one embodiment of the invention the outputs of the first resolver are directly inputted into two separate multipliers and the outputs of the second resolver are inputted into the two separate multipliers, after being demodulated in a pair of demodulator circuits. The multiplied signals are then added in an adder circuit to provide a directional sensitive output. In another embodiment the outputs from the first resolver is modulated in separate modulator circuits and the output from the modulator circuits are used to excite the second resolver. The outputs from the second resolver are demodulated in separate demodulator circuit and added in an adder circuit to provide a direction sensitive rate output.

  9. Dual control active superconductive devices

    DOEpatents

    Martens, Jon S.; Beyer, James B.; Nordman, James E.; Hohenwarter, Gert K. G.

    1993-07-20

    A superconducting active device has dual control inputs and is constructed such that the output of the device is effectively a linear mix of the two input signals. The device is formed of a film of superconducting material on a substrate and has two main conduction channels, each of which includes a weak link region. A first control line extends adjacent to the weak link region in the first channel and a second control line extends adjacent to the weak link region in the second channel. The current flowing from the first channel flows through an internal control line which is also adjacent to the weak link region of the second channel. The weak link regions comprise small links of superconductor, separated by voids, through which the current flows in each channel. Current passed through the control lines causes magnetic flux vortices which propagate across the weak link regions and control the resistance of these regions. The output of the device taken across the input to the main channels and the output of the second main channel and the internal control line will constitute essentially a linear mix of the two input signals imposed on the two control lines. The device is especially suited to microwave applications since it has very low input capacitance, and is well suited to being formed of high temperature superconducting materials since all of the structures may be formed coplanar with one another on a substrate.

  10. Dual-band dual field-of-view TVWS prototype

    NASA Astrophysics Data System (ADS)

    Bergeron, A.; Jerominek, H.; Doucet, M.; Lagacé, F.; Desnoyers, N.; Bernier, S.; Mercier, L.; Boucher, M.-A.; Jacob, M.; Alain, C.; Pope, T. D.; Laou, P.

    2006-05-01

    A dual band thermal/visible weapon sight (TVWS) prototype was developed by INO in collaboration with DRDC Valcartier. The TVWS operates in the 8-12 μm infrared (IR) and 300-900 nm visible wavebands for enhanced vision capabilities in day and night operations. It is equipped with lightweight athermalized coaxial catadioptric objectives, a bolometric IR imager operating in a microscan mode providing an effective resolution of 320 x 240 pixels and a visible image intensifier of 768 x 493 pixels. The TVWS is equipped with a miniature shutter for automatic offset calibration. Real-time imaging at 30 fps is available. Both the visible and IR images can be toggled with a single touch button and displayed on an integrated color micro liquid crystal display (LCD). The TVWS also has a standard video output via a coaxial connector. An integrated wireless analog RF link can be used to send images to a remote command control. The sight has an adjustable electronic crosshair and two manual focuses from 25 m to infinity. On-board processing capabilities were added to introduce specific functionalities such as image polarity inversion (black hot/white hot) and image enhancement. This TVWS model is also very lightweight (~ 1900 grams) and compact (volume of 142 cubic inches). It offers human size target detection at 800 m and recognition at 200 m (Johnson criteria) with the IR waveband while offering the human recognition at up to 800 m with the visible waveband. The TVWS is adapted for weaver or Picatinny rail mounting.

  11. Unidirectional, dual-comb lasing under multiple pulse formation mechanisms in a passively mode-locked fiber ring laser.

    PubMed

    Liu, Ya; Zhao, Xin; Hu, Guoqing; Li, Cui; Zhao, Bofeng; Zheng, Zheng

    2016-09-19

    Dual-comb lasers simultaneously generating asynchronous ultrashort pulses could be an intriguing alternative to the current dual-laser comb source. When generated through a common light path, the low common-mode noises and good coherence between the pulse trains could be realized. Here we demonstrate the completely common-path, unidirectional dual-comb lasing using a carbon nanotube saturable absorber with additional pulse narrowing and broadening mechanisms. The interactions between multiple soliton formation mechanisms result in bifurcation into unusual two-pulse states with pulses of four-fold bandwidth difference and tens-of-Hz repetition rate difference. Coherence between the pulses is verified by the asynchronous cross-sampling and dual-comb spectroscopy measurements.

  12. Stimulated dual-band infrared computed tomography: A tool to inspect the aging infrastructure

    SciTech Connect

    Del Grande, N.K.; Durbin, P.F.

    1995-06-27

    The authors have developed stimulated dual-band infrared (IR) computed tomography as a tool to inspect the aging infrastructure. The system has the potential to locate and quantify structural damage within airframes and bridge decks. Typically, dual-band IR detection methods improve the signal-to-noise ratio by a factor of ten, compared to single-band IR detection methods. They conducted a demonstration at Boeing using a uniform pulsed-heat source to stimulate IR images of hidden defects in the 727 fuselage. The dual-band IR camera and image processing system produced temperature, thermal inertia, and cooling-rate maps. In combination, these maps characterized the defect site, size, depth, thickness and type. The authors quantified the percent metal loss from corrosion above a threshold of 5%, with overall uncertainties of 3%. Also, they conducted a feasibility study of dual-band IR thermal imaging for bridge deck inspections. They determined the sites and relative concrete displacement of 2-in. and 4-in. deep delaminations from thin styrofoam implants in asphalt-covered concrete slabs. They demonstrated the value of dual-band IR computed tomography to quantify structural damage within flash-heated airframes and naturally-heated bridge decks.

  13. Performance of today’s dual energy CT and future multi energy CT in virtual non-contrast imaging and in iodine quantification: A simulation study

    SciTech Connect

    Faby, Sebastian Kuchenbecker, Stefan; Sawall, Stefan; Kachelrieß, Marc; Simons, David; Schlemmer, Heinz-Peter; Lell, Michael

    2015-07-15

    Purpose: To study the performance of different dual energy computed tomography (DECT) techniques, which are available today, and future multi energy CT (MECT) employing novel photon counting detectors in an image-based material decomposition task. Methods: The material decomposition performance of different energy-resolved CT acquisition techniques is assessed and compared in a simulation study of virtual non-contrast imaging and iodine quantification. The material-specific images are obtained via a statistically optimal image-based material decomposition. A projection-based maximum likelihood approach was used for comparison with the authors’ image-based method. The different dedicated dual energy CT techniques are simulated employing realistic noise models and x-ray spectra. The authors compare dual source DECT with fast kV switching DECT and the dual layer sandwich detector DECT approach. Subsequent scanning and a subtraction method are studied as well. Further, the authors benchmark future MECT with novel photon counting detectors in a dedicated DECT application against the performance of today’s DECT using a realistic model. Additionally, possible dual source concepts employing photon counting detectors are studied. Results: The DECT comparison study shows that dual source DECT has the best performance, followed by the fast kV switching technique and the sandwich detector approach. Comparing DECT with future MECT, the authors found noticeable material image quality improvements for an ideal photon counting detector; however, a realistic detector model with multiple energy bins predicts a performance on the level of dual source DECT at 100 kV/Sn 140 kV. Employing photon counting detectors in dual source concepts can improve the performance again above the level of a single realistic photon counting detector and also above the level of dual source DECT. Conclusions: Substantial differences in the performance of today’s DECT approaches were found for the

  14. Dual Treatments as Starting Point for Integrative Perceptions in Teaching Mathematics

    ERIC Educational Resources Information Center

    Kërënxhi, Svjetllana; Gjoci, Pranvera

    2015-01-01

    In this paper, we recommend mathematical teaching through dual treatments. The dual treatments notion, classified in dual interpretations, dual analyses, dual solutions, and dual formulations, is explained through concrete examples taken from mathematical textbooks of elementary education. Dual treatments provide opportunities for creating…

  15. Fate and Transport of Nitrate in an Alpine Catchment Based on Dual-Isotopic and End-Member Mixing Analysis

    NASA Astrophysics Data System (ADS)

    Williams, M. W.; Liu, F.; Kendall, C.

    2003-12-01

    Attempts to understand nitrate loss from small watersheds have been the focus of much research. In general, these results have shown that understanding how sources and flowpaths of nitrate-rich waters change with time necessitates a combination of isotopic, chemical, and hydrometric data. New and evolving tools to understand the fate and transport of nitrate include dual-isotopic analysis of both the nitrogen and oxygen atoms in the nitrate molecule, and end-member mixing analysis (EMMA). However, to-date no one has combined these two approaches. Here we present results from both dual-isotope analysis and EMMA to understand the fate and transport of nitrate in the high-elevation Green Lakes watershed of the Colorado Front Range. Thirty-five samples were collected and analyzed for the dual isotopes of nitrate, and showed that values of δ 18O in atmospheric deposition had considerable overlap with values in stream waters. There was a strong counterclockwise pattern of hysteresis when δ 18O is plotted versus stream discharge, consistent with a mixture of atmospheric and microbial nitrate sources on the rising limb of the hydrograph, then mostly a microbial source on the recession limb of the hydrograph. A chemograph of nitrate sources developed using EMMA shows atmospheric deposition the predominant source at the initiation of snowmelt runoff, with soil water and talus becoming the dominant source at peak runoff, and talus-water and baseflow both important on the recession limb of the hydrograph. We were able to qualitatively evaluate the EMMA results by developing a 2-component nitrate source model using the dual-isotope values. The dual-isotope mixing model agreed well with the atmospheric and subsurface sources of nitrate identified using EMMA.

  16. Ion source

    DOEpatents

    Leung, Ka-Ngo; Ehlers, Kenneth W.

    1984-01-01

    A magnetic filter for an ion source reduces the production of undesired ion species and improves the ion beam quality. High-energy ionizing electrons are confined by the magnetic filter to an ion source region, where the high-energy electrons ionize gas molecules. One embodiment of the magnetic filter uses permanent magnets oriented to establish a magnetic field transverse to the direction of travel of ions from the ion source region to the ion extraction region. In another embodiment, low energy 16 eV electrons are injected into the ion source to dissociate gas molecules and undesired ion species into desired ion species.

  17. Getting Ahead with Dual Credit: Dual-Credit Participation, Outcomes, and Opportunities in Idaho

    ERIC Educational Resources Information Center

    Holten, Brandi; Pierson, Ashley

    2016-01-01

    This report provides a portrait of dual-credit participation rates and trends between the 2011-12 and 2014-15 school years. Dual-credit participation by demographic characteristics such as race/ethnicity, gender, and socioeconomic status is explored throughout each of the five briefs contained within this report. Each report brief also includes…

  18. Dual-Compartment Inflatable Suitlock

    NASA Technical Reports Server (NTRS)

    Kennedy, Kriss J.; Guirgis, Peggy L.; Boyle, Robert M.

    2013-01-01

    There is a need for an improvement over current NASA Extravehicular Activity (EVA) technology. The technology must allow the capacity for quicker, more efficient egress/ingress, allow for shirtsleeve suit maintenance, be compact in transport, and be applicable to environments ranging from planetary surface (partial-g) to orbital or deep space zero-g environments. The technology must also be resistant to dust and other foreign contaminants that may be present on or around a planetary surface. The technology should be portable, and be capable of docking with a variety of habitats, ports, stations, vehicles, and other pressurized modules. The Dual-Compartment Inflatable Suitlock (DCIS) consists of three hard inline bulkheads, separating two cylindrical membrane-walled compartments. The Inner Bulkhead can be fitted with a variety of hatch types, docking flanges, and mating hardware, such as the Common Berthing Mechanism (CBM), for the purpose of mating with vehicles, habitats, and other pressurized modules. The Inner Bulkhead and Center Bulkhead function as the end walls of the Inner Compartment, which during operations, would stay pressurized, either matching the pressure of the habitat or acting as a lower-pressure transitional volume. The Inner Compartment contains donning/doffing fixtures and inner suit-port hatches. The Center Bulkhead has two integrated suit-ports along with a maintenance hatch. The Center Bulkhead and Outer Bulkhead function as the end walls of the Outer Compartment, which stays at vacuum during normal operations. This allows the crewmember to quickly don a suit, and egress the suitlock without waiting for the Outer Compartment to depressurize. The Outer Compartment can be pressurized infrequently for both nominal and off-nominal suit maintenance tasks, allowing shirtsleeve inspections and maintenance/repair of the environmental suits. The Outer Bulkhead has a pressure-assisted hatch door that stays open and stowed during EVA operations, but can

  19. Dual Comb Fourier Transform Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hänsch, T. W.; Picqué, N.

    2010-06-01

    The advent of laser frequency combs a decade ago has already revolutionized optical frequency metrology and precision spectroscopy. Extensions of laser combs from the THz region to the extreme ultraviolet and soft x-ray frequencies are now under exploration. Such laser combs have become enabling tools for a growing tree of applications, from optical atomic clocks to attosecond science. Recently, the millions of precisely controlled laser comb lines that can be produced with a train of ultrashort laser pulses have been harnessed for highly multiplexed molecular spectroscopy. Fourier multi-heterodyne spectroscopy, dual comb spectroscopy, or asynchronous optical sampling spectroscopy with frequency combs are emerging as powerful new spectroscopic tools. Even the first proof-of-principle experiments have demonstrated a very exciting potential for ultra-rapid and ultra-sensitive recording of complex molecular spectra. Compared to conventional Fourier transform spectroscopy, recording times could be shortened from seconds to microseconds, with intriguing prospects for spectroscopy of short lived transient species. Longer recording times allow high resolution spectroscopy of molecules with extreme precision, since the absolute frequency of each laser comb line can be known with the accuracy of an atomic clock. The spectral structure of sharp lines of a laser comb can be very useful even in the recording of broadband spectra without sharp features, as they are e.g. encountered for molecular gases or in the liquid phase. A second frequency comb of different line spacing permits the generation of a comb of radio frequency beat notes, which effectively map the optical spectrum into the radio frequency regime, so that it can be recorded with a single fast photodetector, followed by digital signal analysis. In the time domain, a pulse train of a mode-locked femtosecond laser excites some molecular medium at regular time intervals. A second pulse train of different repetition

  20. Versatile and Sensitive Dual Comb Fourier Transform Spectroscopy

    NASA Astrophysics Data System (ADS)

    Jacquey, M.; Jacquet, P.; Mandon, J.; Thon, R.; Guelachvili, G.; Hänsch, T. W.; Picqué, N.

    2010-06-01

    Fourier transform spectroscopy based on time-domain interferences between two slightly detuned frequency comb sources holds much promise for the real-time diagnostic of gaseous, liquid or solid-state samples. In one very recent example, cavity-enhanced absorption spectroscopy with two infrared frequency combs has demonstrated a dramatically enhanced sensitivity, compared to conventional Fourier spectroscopy, with intriguing implications for instantaneous trace gas analysis. It however remains challenging to match continuously the comb and cavity modes across a broad spectral bandwidth during the time of a measurement. An obvious alternative for reaching a long interaction path is a conventional multipass cell. Additionally, differential detection schemes may be devised to increase the dynamic range of the interferometric measurements, thus providing enhanced signal to noise ratio. Experimental demonstrations will be given in the 1.5 μm region with a dual comb set-up based on two Er-doped fiber femtosecond lasers. The versatility and performances of these solutions will be compared to the cavity-enhanced dual comb technique and other state-of-the-art alternatives. P. Jacquet, J. Mandon, B. Bernhardt, R. Holzwarth, G. Guelachvili, T. W. Hänsch, N. Picqué, Frequency Comb Fourier Transform Spectroscopy with kHz Optical Resolution, The Optical Society of America, Washington, DC 2009, paper FMB2 (2009). B. Bernhardt, A. Ozawa, P. Jacquet, M. Jacquey, Y. Kobayashi, T. Udem, R. Holzwarth, G. Guelachvili, T.W. Hänsch, N. Picqué, Cavity-enhanced dual-comb spectroscopy, Nature Photonics 4, 55-57 (2010),

  1. Detecting Dual AGN at High Redshift

    NASA Astrophysics Data System (ADS)

    Barrows, Robert S.

    2012-01-01

    The existence of supermassive black holes (SMBHs) in most, if not all, galaxies, along with observations of galaxy mergers, suggests that pairs of SMBHs should exist for some time in the merger remnant. Observational evidence for these systems at kpc-scale separations (i.e. dual AGN) has dramatically increased recently through a combination of spectral and morphological selections. I discuss observations of CXOXBJ142607.6+353351 (CXOJ1426+35), a candidate dual AGN at z=1.175, and put its properties, including significant obscuration, within the context of other candidate/confirmed dual AGN at lower redshifts. Though dual AGN are expected to be more common at higher redshifts, they are more difficult to detect. Furthermore, adding to the difficulties of detection are a number of other physical mechanisms which can mimic the spectroscopic signature of two Type 2 AGN. In particular, I will discuss the possibility of strong outflows from an AGN. These outflow phenomena can be an important feedback mechanism in galaxies and are apparently common in AGN, making them a viable alternative to the dual AGN scenario. Based on our candidate's luminosity and emission line intensities, we find that an outflow is a possibility. If this is the case, such an outflow would be especially strong and has implications for AGN feedback in galaxies. However, the dual AGN scenario cannot be ruled out, and at z=1.175, the two putative AGN could potentially be resolved with Chandra. Other candidate dual AGN at similar redshifts and with significant obscuration could also be confirmed this way. This research was sponsored by the Strategic University Research Partnership Program, the National Aeronautics and Space Administration and the Arkansas NASA EPSCoR program.

  2. Unraveling Executive Functioning in Dual Diagnosis

    PubMed Central

    Duijkers, Judith C. L. M.; Vissers, Constance Th. W. M.; Egger, Jos I. M.

    2016-01-01

    In mental health, the term dual-diagnosis is used for the co-occurrence of Substance Use Disorder (SUD) with another mental disorder. These co-occurring disorders can have a shared cause, and can cause/intensify each other’s expression. Forming a threat to health and society, dual-diagnosis is associated with relapses in addiction-related behavior and a destructive lifestyle. This is due to a persistent failure to control impulses and the maintaining of inadequate self-regulatory behavior in daily life. Thus, several aspects of executive functioning like inhibitory, shifting and updating processes seem impaired in dual-diagnosis. Executive (dys-)function is currently even seen as a shared underlying key component of most mental disorders. However, the number of studies on diverse aspects of executive functioning in dual-diagnosis is limited. In the present review, a systematic overview of various aspects of executive functioning in dual-diagnosis is presented, striving for a prototypical profile of patients with dual-diagnosis. Looking at empirical results, inhibitory and shifting processes appear to be impaired for SUD combined with schizophrenia, bipolar disorder or cluster B personality disorders. Studies involving updating process tasks for dual-diagnosis were limited. More research that zooms in to the full diversity of these executive functions is needed in order to strengthen these findings. Detailed insight in the profile of strengths and weaknesses that underlies one’s behavior and is related to diagnostic classifications, can lead to tailor-made assessment and indications for treatment, pointing out which aspects need attention and/or training in one’s self-regulative abilities. PMID:27445939

  3. Data Sharing and Dual-Use Issues

    PubMed Central

    Bezuidenhout, Louise

    2016-01-01

    The concept of dual-use encapsulates the potential for well-intentioned, beneficial scientific research to also be misused by a third party for malicious ends. The concept of dual-use challenges scientists to look beyond the immediate outcomes of their research and to develop an awareness of possible future (mis)uses of scientific research. Since 2001 much attention has been paid to the possible need to regulate the dual-use potential of the life sciences. Regulation initiatives fall under two broad categories—those that develop the ethical education of scientists and foster an awareness and responsibility of dual-use issues, and those which assess the regulation of information being generated by current research. Both types of initiatives are premised on a cautious, risk-adverse philosophy which advocates careful examination of all future endpoints of research endeavors. This caution advocated within initiatives such as pre-publication review of journal articles contrasts to the obligation to share underpinning data sharing discussions. As the dual-use debate has yet to make a significant impact on data sharing discussions (and vice versa) it is possible that these two areas of knowledge control may present areas of ethical conflict for scientists, and thus need to be more closely examined. This paper examines the tension between the obligation to share exemplified by data sharing principles and the concerns raised by the risk-cautious culture of the dual-use debates. The paper concludes by reflecting on the issues of responsibility as raised by dual-use as relating to data sharing, such as the chain of custody for shared data. PMID:21805213

  4. Dual polarized, heat spreading rectenna

    NASA Technical Reports Server (NTRS)

    Epp, Larry W. (Inventor); Khan, Abdur R. (Inventor); Smith, R. Peter (Inventor); Smith, Hugh K. (Inventor)

    1999-01-01

    An aperture coupled patch splits energy from two different polarization components to different locations to spread heat. In addition, there is no physical electrical connection between the slot, patch and circuitry. The circuitry is located under a ground plane which shields against harmonic radiation back to the RF source.

  5. Comparison of Propane and Methane Performance and Emissions in a Turbocharged Direct Injection Dual Fuel Engine

    SciTech Connect

    Gibson, C. M.; Polk, A. C.; Shoemaker, N. T.; Srinivasan, K. K.; Krishnan, S. R.

    2011-01-01

    With increasingly restrictive NO x and particulate matter emissions standards, the recent discovery of new natural gas reserves, and the possibility of producing propane efficiently from biomass sources, dual fueling strategies have become more attractive. This paper presents experimental results from dual fuel operation of a four-cylinder turbocharged direct injection (DI) diesel engine with propane or methane (a natural gas surrogate) as the primary fuel and diesel as the ignition source. Experiments were performed with the stock engine control unit at a constant speed of 1800 rpm, and a wide range of brake mean effective pressures (BMEPs) (2.7-11.6 bars) and percent energy substitutions (PESs) of C 3 H 8 and CH 4. Brake thermal efficiencies (BTEs) and emissions (NO x, smoke, total hydrocarbons (THCs), CO, and CO 2) were measured. Maximum PES levels of about 80-95% with CH 4 and 40-92% with C 3 H 8 were achieved. Maximum PES was limited by poor combustion efficiencies and engine misfire at low loads for both C 3 H 8 and CH 4, and the onset of knock above 9 bar BMEP for C 3 H 8. While dual fuel BTEs were lower than straight diesel BTEs at low loads, they approached diesel BTE values at high loads. For dual fuel operation, NO x and smoke reductions (from diesel values) were as high as 66-68% and 97%, respectively, but CO and THC emissions were significantly higher with increasing PES at all engine loads

  6. ION SOURCE

    DOEpatents

    Martina, E.F.

    1958-04-22

    An improved ion source particularly adapted to provide an intense beam of ions with minimum neutral molecule egress from the source is described. The ion source structure includes means for establishing an oscillating electron discharge, including an apertured cathode at one end of the discharge. The egress of ions from the source is in a pencil like beam. This desirable form of withdrawal of the ions from the plasma created by the discharge is achieved by shaping the field at the aperture of the cathode. A tubular insulator is extended into the plasma from the aperture and in cooperation with the electric fields at the cathode end of the discharge focuses the ions from the source,

  7. Dual adaptive control: Design principles and applications

    NASA Technical Reports Server (NTRS)

    Mookerjee, Purusottam

    1988-01-01

    The design of an actively adaptive dual controller based on an approximation of the stochastic dynamic programming equation for a multi-step horizon is presented. A dual controller that can enhance identification of the system while controlling it at the same time is derived for multi-dimensional problems. This dual controller uses sensitivity functions of the expected future cost with respect to the parameter uncertainties. A passively adaptive cautious controller and the actively adaptive dual controller are examined. In many instances, the cautious controller is seen to turn off while the latter avoids the turn-off of the control and the slow convergence of the parameter estimates, characteristic of the cautious controller. The algorithms have been applied to a multi-variable static model which represents a simplified linear version of the relationship between the vibration output and the higher harmonic control input for a helicopter. Monte Carlo comparisons based on parametric and nonparametric statistical analysis indicate the superiority of the dual controller over the baseline controller.

  8. Dual multispectral and 3D structured light laparoscope

    NASA Astrophysics Data System (ADS)

    Clancy, Neil T.; Lin, Jianyu; Arya, Shobhit; Hanna, George B.; Elson, Daniel S.

    2015-03-01

    Intraoperative feedback on tissue function, such as blood volume and oxygenation would be useful to the surgeon in cases where current clinical practice relies on subjective measures, such as identification of ischaemic bowel or tissue viability during anastomosis formation. Also, tissue surface profiling may be used to detect and identify certain pathologies, as well as diagnosing aspects of tissue health such as gut motility. In this paper a dual modality laparoscopic system is presented that combines multispectral reflectance and 3D surface imaging. White light illumination from a xenon source is detected by a laparoscope-mounted fast filter wheel camera to assemble a multispectral image (MSI) cube. Surface shape is then calculated using a spectrally-encoded structured light (SL) pattern detected by the same camera and triangulated using an active stereo technique. Images of porcine small bowel were acquired during open surgery. Tissue reflectance spectra were acquired and blood volume was calculated at each spatial pixel across the bowel wall and mesentery. SL features were segmented and identified using a `normalised cut' algoritm and the colour vector of each spot. Using the 3D geometry defined by the camera coordinate system the multispectral data could be overlaid onto the surface mesh. Dual MSI and SL imaging has the potential to provide augmented views to the surgeon supplying diagnostic information related to blood supply health and organ function. Future work on this system will include filter optimisation to reduce noise in tissue optical property measurement, and minimise spot identification errors in the SL pattern.

  9. A portable dual frequency comb spectrometer for atmospheric applications

    NASA Astrophysics Data System (ADS)

    Cossel, Kevin; Waxman, Eleanor; Truong, Gar-Wing; Giorgetta, Fabrizio; Swann, William; Rieker, Gregory; Coddington, Ian; Newbury, Nathan

    2016-04-01

    Dual frequency comb (DFC) spectroscopy is a new technique that combines broad spectral bandwidth, high spectral resolution, rapid data acquisition, and high sensitivity. In addition, unlike standard Fourier-transform spectroscopy, it has an almost ideal instrument lineshape function, does not require recalibration, and has no moving parts. These features make DFC spectroscopy well suited for accurate measurements of multiple species simultaneously. Because the frequency comb lasers can be well collimated, such a system can be used for long open-path measurements with path lengths ranging from hundreds of meters to several kilometers. This length scale bridges the gap between point measurements and satellite-based measurements and is ideal for providing information about local sources and quanitfying emissions. Here we show a fully portable DFC spectrometer operating over a wide spectral region in the near-infrared (about 1.5-2.1 μm or 6670-4750 cm-1 sampled at 0.0067 cm-1) and across several different open-air paths. The current spectrometer fits in about a 500 L volume and has low power consumption. It provides simultaneous measurements of CO2, CH4, and water isotopes with a time resolution of seconds to minutes. We will provide an introduction to dual frequency comb spectroscopy and then discuss the design and performance of the system.

  10. Light Source

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Research on food growth for long duration spacecraft has resulted in a light source for growing plants indoors known as Qbeam, a solid state light source consisting of a control unit and lamp. The light source, manufactured by Quantum Devices, Inc., is not very hot, although it generates high intensity radiation. When Ron Ignatius, an industrial partner of WCSAR, realized that terrestrial plant research lighting was not energy efficient enough for space use, he and WCSAR began to experiment with light emitting diodes. A line of LED products was developed, and QDI was formed to market the technology. An LED-based cancer treatment device is currently under development.

  11. The Grassmannian origin of dual superconformal invariance

    NASA Astrophysics Data System (ADS)

    Arkani-Hamed, Nima; Cachazo, Freddy; Cheung, Clifford

    2010-03-01

    A dual formulation of the S Matrix for mathcal {N} = 4 SYM has recently been presented, where all leading singularities of n-particle N k-2MHV amplitudes are given as an integral over the Grassmannian G( k, n), with cyclic symmetry, parity and superconformal invariance manifest. In this short note we show that the dual superconformal invariance of this object is also manifest. The geometry naturally suggests a partial integration and simple change of variable to an integral over G( k - 2, n). This change of variable precisely corresponds to the mapping between usual momentum variables and the “momentum twistors” introduced by Hodges, and yields an elementary derivation of the momentumtwistor space formula very recently presented by Mason and Skinner, which is manifestly dual superconformal invariant. Thus the G( k, n) Grassmannian formulation allows a direct understanding of all the important symmetries of mathcal {N} = 4 SYM scattering amplitudes.

  12. Integrated Power Source Grant

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Traditional spacecraft power systems incorporate a solar array energy source, an energy storage element (battery), and battery charge control and bus voltage regulation electronics to provide continuous electrical power for spacecraft systems and instruments. Dedicated power conditioning components provide limited fault isolation between systems and instruments, while a centralized power-switching unit provides spacecraft load control. Battery undervoltage conditions are detected by the spacecraft processor, which removes fault conditions and non-critical loads before permanent battery damage can occur. Cost effective operation of a micro-sat constellation requires a fault tolerant spacecraft architecture that minimizes on-orbit operational costs by permitting autonomous reconfiguration in response to unexpected fault conditions. A new micro-sat power system architecture that enhances spacecraft fault tolerance and improves power system survivability by continuously managing the battery charge and discharge processes on a cell-by-cell basis has been developed. This architecture is based on the Integrated Power Source (US patent 5644207), which integrates dual junction solar cells, Lithium Ion battery cells, and processor based charge control electronics into a structural panel that can be deployed or used to form a portion of the outer shell of a micro-spacecraft. The first generation Integrated Power Source is configured as a one inch thick panel in which prismatic Lithium Ion battery cells are arranged in a 3x7 matrix (26VDC) and a 3x1 matrix (3.7VDC) to provide the required output voltages and load currents. A multi-layer structure holds the battery cells, as well as the thermal insulators that are necessary to protect the Lithium Ion battery cells from the extreme temperatures of the solar cell layer. Independent thermal radiators, located on the back of the panel, are dedicated to the solar cell array, the electronics, and the battery cell array. In deployed

  13. Dual-domain point diffraction interferometer

    DOEpatents

    Naulleau, Patrick P.; Goldberg, Kenneth Alan

    2000-01-01

    A hybrid spatial/temporal-domain point diffraction interferometer (referred to as the dual-domain PS/PDI) that is capable of suppressing the scattered-reference-light noise that hinders the conventional PS/PDI is provided. The dual-domain PS/PDI combines the separate noise-suppression capabilities of the widely-used phase-shifting and Fourier-transform fringe pattern analysis methods. The dual-domain PS/PDI relies on both a more restrictive implementation of the image plane PS/PDI mask and a new analysis method to be applied to the interferograms generated and recorded by the modified PS/PDI. The more restrictive PS/PDI mask guarantees the elimination of spatial-frequency crosstalk between the signal and the scattered-light noise arising from scattered-reference-light interfering with the test beam. The new dual-domain analysis method is then used to eliminate scattered-light noise arising from both the scattered-reference-light interfering with the test beam and the scattered-reference-light interfering with the "true" pinhole-diffracted reference light. The dual-domain analysis method has also been demonstrated to provide performance enhancement when using the non-optimized standard PS/PDI design. The dual-domain PS/PDI is essentially a three-tiered filtering system composed of lowpass spatial-filtering the test-beam electric field using the more restrictive PS/PDI mask, bandpass spatial-filtering the individual interferogram irradiance frames making up the phase-shifting series, and bandpass temporal-filtering the phase-shifting series as a whole.

  14. Oxygen/Alcohol Dual Thrust RCS Engines

    NASA Technical Reports Server (NTRS)

    Angstadt, Tara; Hurlbert, Eric

    1999-01-01

    A non-toxic dual thrust RCS engine offers significant operational, safety, and performance advantages to the space shuttle and the next generation RLVs. In this concept, a single engine produces two thrust levels of 25 and 870 lbf. The low thrust level is provided by the spark torch igniter, which, with the addition of 2 extra valves, can also be made to function as a vernier. A dual thrust RCS engine allows 38 verniers to be packaged more efficiently on a vehicle. These 38 vemiers improve translation and reduce cross coupling, thereby providing more pure roll, pitch, and yaw maneuvers of the vehicle. Compared to the 6 vemiers currently on the shuttle, the 38 dual thrust engines would be 25 to 40% more efficient for the same maneuvers and attitude control. The vernier thrust level also reduces plume impingement and contamination concerns. Redundancy is also improved, thereby improving mission success reliability. Oxygen and ethanol are benign propellants which do not create explosive reaction products or contamination, as compared to hypergolic propellants. These characteristics make dual-thrust engines simpler to implement on a non-toxic reaction control system. Tests at WSTF in August 1999 demonstrated a dual-thrust concept that is successful with oxygen and ethanol. Over a variety of inlet pressures and mixture ratios at 22:1 area ratio, the engine produced between 230 and 297 sec Isp, and thrust levels from 8 lbf. to 50 lbf. This paper describes the benefits of dual-thrust engines and the recent results from tests at WSTF.

  15. NEUTRON SOURCES

    DOEpatents

    Richmond, J.L.; Wells, C.E.

    1963-01-15

    A neutron source is obtained without employing any separate beryllia receptacle, as was formerly required. The new method is safer and faster, and affords a source with both improved yield and symmetry of neutron emission. A Be container is used to hold and react with Pu. This container has a thin isolating layer that does not obstruct the desired Pu--Be reaction and obviates procedures previously employed to disassemble and remove a beryllia receptacle. (AEC)

  16. Monolithic dual-mode distributed feedback semiconductor laser for tunable continuous-wave terahertz generation.

    PubMed

    Kim, Namje; Shin, Jaeheon; Sim, Eundeok; Lee, Chul Wook; Yee, Dae-Su; Jeon, Min Yong; Jang, Yudong; Park, Kyung Hyun

    2009-08-03

    We report on a monolithic dual-mode semiconductor laser operating in the 1550-nm range as a compact optical beat source for tunable continuous-wave (CW) terahertz (THz) generation. It consists of two distributed feedback (DFB) laser sections and one phase section between them. Each wavelength of the two modes can be independently tuned by adjusting currents in micro-heaters which are fabricated on the top of the each DFB section. The continuous tuning of the CW THz emission from Fe(+)-implanted InGaAs photomixers is successfully demonstrated using our dual-mode laser as the excitation source. The CW THz frequency is continuously tuned from 0.17 to 0.49 THz.

  17. Quantification of Urinary Stone Composition in Mixed Stones Using Dual-Energy CT: A Phantom Study

    PubMed Central

    Leng, Shuai; Huang, Alice; Montoya, Juan; Duan, Xinhui; Williams, James C.; McCollough, Cynthia H.

    2016-01-01

    Purpose To demonstrate the feasibility of using dual-energy computed tomography to accurately quantify uric acid and non-uric-acid components in urinary stones having mixed composition. Materials and Methods A total of 24 urinary stones were analyzed with microCT to serve as the reference standard for uric acid and non-uric-acid composition. These stones were placed in water phantoms to simulate body attenuation of slim to obese adults and scanned on a third-generation dual-source scanner using dual-energy modes adaptively selected based on phantom size. CT number ratio, which is distinct for different materials, was calculated for each pixel of the stones. Each pixel was then classified as uric acid and non-uric-acid by comparing the CT number ratio with preset thresholds ranging from 1.1 to 1.7. Minimal, maximal and root-mean-square errors were calculated by comparing composition to the reference standard and the threshold with the minimal root-mean-square-error was determined. A paired t-test was performed to compare the stone composition determined with dual-energy CT with the reference standard obtained with microCT. Results The optimal CT number ratio threshold ranged from 1.27 to 1.55, dependent on phantom size. The root-mean-square error ranged from 9.60% to 12.87% across all phantom sizes. Minimal and maximal absolute error ranged from 0.04% to 1.24% and from 22.05% to 35.46%, respectively. Dual-energy CT and the reference microCT did not differ significantly on uric acid and non-uric-acid composition (P from 0.20 to 0.96, paired t-test). Conclusion Accurate quantification of uric acid and non-uric-acid composition in mixed stones is possible using dual-energy CT. PMID:27224260

  18. Dual Causality and the Autonomy of Biology.

    PubMed

    Bock, Walter J

    2017-03-01

    Ernst Mayr's concept of dual causality in biology with the two forms of causes (proximate and ultimate) continues to provide an essential foundation for the philosophy of biology. They are equivalent to functional (=proximate) and evolutionary (=ultimate) causes with both required for full biological explanations. The natural sciences can be classified into nomological, historical nomological and historical dual causality, the last including only biology. Because evolutionary causality is unique to biology and must be included for all complete biological explanations, biology is autonomous from the physical sciences.

  19. A dual-threshold radar detection system

    NASA Astrophysics Data System (ADS)

    Hammerle, K. J.

    It is known that the beam agility of a phased-array radar can be utilized to enhance target detection capability as compared to a radar which has the same power but which radiates its energy uniformly over the solid angle being surveilled. A dual-threshold approach for realizing this enhancement is examined. Quantitative results are presented parametrically for four signal fluctuation models. The study also identifies the optimum combination of dual-threshold design parameters for each target model under a wide range of imposed system constraints such as the allowed number of false alarms per beam position. It is shown that under certain imposed constraints, no enhancement is possible.

  20. Integrable Deformations of T -Dual σ Models

    NASA Astrophysics Data System (ADS)

    Borsato, Riccardo; Wulff, Linus

    2016-12-01

    We present a method to deform (generically non-Abelian) T duals of two-dimensional σ models, which preserves classical integrability. The deformed models are identified by a linear operator ω on the dualized subalgebra, which satisfies the 2-cocycle condition. We prove that the so-called homogeneous Yang-Baxter deformations are equivalent, via a field redefinition, to our deformed models when ω is invertible. We explain the details for deformations of T duals of principal chiral models, and present the corresponding generalization to the case of supercoset models.

  1. Dual diagnosis among physicians: a clinical perspective.

    PubMed

    Braquehais, María Dolores; Lusilla, Pilar; Bel, Miquel Jordi; Navarro, María Cecilia; Nasillo, Viviana; Díaz, Albert; Valero, Sergi; Padrós, Jaume; Bruguera, Eugeni; Casas, Miquel

    2014-01-01

    Co-occurrence of mental disorders and substance use disorders (dual diagnosis) among doctors is a cause of serious concern due to its negative personal, professional, and social consequences. This work provides an overview of the prevalence of dual diagnosis among physicians, suggests a clinical etiological model to explain the development of dual diagnosis in doctors, and recommends some treatment strategies specifically for doctors. The most common presentation of dual diagnosis among doctors is the combination of alcohol use disorders and affective disorders. There are also high rates of self-medication with benzodiazepines, legal opiates, and amphetamines compared to the general population, and cannabis use disorders are increasing, mainly in young doctors. The prevalence of nicotine dependence varies from one country to another depending on the nature of public health policies. Emergency medicine physicians, psychiatrists, and anaesthesiologists are at higher risk for developing a substance use disorder compared with other doctors, perhaps because of their knowledge of and access to certain legal drugs. Two main pathways may lead doctors toward dual diagnosis: (a) the use of substances (often alcohol or self-prescribed drugs) as an unhealthy strategy to cope with their emotional or mental distress and (b) the use of substances for recreational or other purposes. In both cases, doctors tend to delay seeking help once a problem has been established, often for many years. Denial, minimization, and rationalization are common defense mechanisms, maybe because of the social stigma associated with mental or substance use disorders, the risk of losing employment/medical license, and a professional culture of perfectionism and denial of emotional needs or failures. Personal vulnerability interacts with these factors to increase the risk of a dual diagnosis developing in some individuals. When doctors with substance use disorders accept treatment in programs

  2. Dual-energy contrast-enhanced mammography.

    PubMed

    Travieso Aja, M M; Rodríguez Rodríguez, M; Alayón Hernández, S; Vega Benítez, V; Luzardo, O P

    2014-01-01

    The degree of vascularization in breast lesions is related to their malignancy. For this reason, functional diagnostic imaging techniques have become important in recent years. Dual-energy contrast-enhanced mammography is a new, apparently promising technique in breast cancer that provides information about the degree of vascularization of the lesion in addition to the morphological information provided by conventional mammography. This article describes the state of the art for dual-energy contrast-enhanced mammography. Based on 15 months' clinical experience, we illustrate this review with clinical cases that allow us to discuss the advantages and limitations of this technique.

  3. Dual waveband compact catadioptric imaging spectrometer

    SciTech Connect

    Chrisp, Michael P.

    2012-12-25

    A catadioptric dual waveband imaging spectrometer that covers the visible through short-wave infrared, and the midwave infrared spectral regions, dispersing the visible through shortwave infrared with a zinc selenide grating and midwave infrared with a sapphire prism. The grating and prism are at the cold stop position, enabling the pupil to be split between them. The spectra for both wavebands are focused onto the relevant sections of a single dual waveband detector. Spatial keystone distortion is controlled to less than one tenth of a pixel over the full wavelength range, facilitating the matching of the spectra in the midwave infrared with the shorter wavelength region.

  4. How self-dual is QCD?

    NASA Astrophysics Data System (ADS)

    Alexandru, Andrei; Horváth, Ivan

    2012-01-01

    Vacuum characteristics quantifying dynamical tendency toward self-duality in gauge theories could be used to judge the relevance of classical solutions or the viability of classically motivated vacuum models. Here we decompose the field strength of equilibrium gauge configurations into self-dual and anti-self-dual parts, and apply absolute X-distribution method to the resulting polarization dynamics in order to construct such characteristics. Using lattice regularization and focusing on pure-glue SU(3) gauge theory at zero temperature, we find evidence for positive but very small dynamical tendency for self-duality of vacuum in the continuum limit.

  5. Bone mineral measurement using dual energy x ray densitometry

    NASA Technical Reports Server (NTRS)

    Smith, Steven W.

    1989-01-01

    Bone mineral measurements before and after space missions have shown that weightlessness greatly accelerates bone demineralization. Bone mineral losses as high as 1 to 3 percent per month were reported. Highly precise instrumentation is required to monitor this loss and thereby test the efficacy of treatment. During the last year, a significant improvement was made in Dual-Photon Absorptiometry by replacing the radioactive source with an x ray tube. Advantages of this system include: better precision, lower patient dose, better spacial resolution, and shorter scan times. The high precision and low radiation dose of this technique will allow detection of bone mineral changes of less than 1 percent with measurements conducted directly at the sites of interest. This will allow the required bone mineral studies to be completed in a shorter time with greater confidence.

  6. Dove prism based rotating dual beam bidirectional Doppler OCT

    PubMed Central

    Blatter, Cedric; Coquoz, Séverine; Grajciar, Branislav; Singh, Amardeep S. G.; Bonesi, Marco; Werkmeister, René M.; Schmetterer, Leopold; Leitgeb, Rainer A.

    2013-01-01

    Traditional Doppler OCT is highly sensitive to motion artifacts due to the dependence on the Doppler angle. This limits its accuracy in clinical practice. To overcome this limitation, we use a bidirectional dual beam technique equipped with a novel rotating scanning scheme employing a Dove prism. The volume is probed from two distinct illumination directions with variable controlled incidence plane, allowing for reconstruction of the true flow velocity at arbitrary vessel orientations. The principle is implemented with Swept Source OCT at 1060nm with 100,000 A-Scans/s. We apply the system to resolve pulsatile retinal absolute blood velocity by performing segment scans around the optic nerve head and circumpapillary scan time series. PMID:23847742

  7. Commissioning of a dual-phase xenon TPC at Nikhef

    NASA Astrophysics Data System (ADS)

    Hogenbirk, E.; Aalbers, J.; Bader, M.; Breur, P. A.; Brown, A.; Decowski, M. P.; Tunnell, C.; Walet, R.; Colijn, A. P.

    2016-12-01

    A dual-phase xenon time-projection chamber was built at Nikhef in Amsterdam as a direct dark matter detection R&D facility. In this paper, the setup is presented and the first results from a calibration with a 22Na gamma-ray source are presented. The results show an average light yield of (5.6 ± 0.3) photoelectrons/keV (calculated to 122 keV and zero field) and an electron lifetime of (429±26) μs. The best energy resolution σE / E is (5.8 ± 0.2)% at an energy of 511 keV. This was achieved using a combination of the scintillation and the ionization signals. A photomultiplier tube gain calibration technique, based on the electroluminescence signals occurring from isolated electrons, is presented and its advantages and limitations are discussed.

  8. Dual Use Global Tsunami Monitoring Network and Underwater GNSS

    NASA Astrophysics Data System (ADS)

    Bernard, E. N.

    2015-12-01

    Earthquakes, volcanoes, landslides, slumps, meteorological events and asteroid impacts can generate tsunamis. However, the present tsunami monitoring network is designed to detect tsunamis generated only by subduction zone earthquakes. A global tsunami monitoring system will be presented to detect tsunamis from ANY source within 20 minutes of origin time. Real-time tsunami data from the monitoring system can be used to forecast coastal flooding in advance of tsunami arrival, thus saving lives through early warnings. The global tsunami monitoring system could also be used to expand the coverage of global navigation by satellites to the seafloor of the world's oceans. Since oceans cover over 70% of the surface planet earth, such an expansion of coverage would revolutionize earth sciences as well as tsunami monitoring for all generation mechanisms. A demonstration project is proposed to test and evaluate the dual use concept.

  9. A dual extremum principle for a population equation

    NASA Technical Reports Server (NTRS)

    Chan, W. L.; Leininger, G. G.

    1974-01-01

    A dual extremum principle for the Verhulst-Pearl population equation is constructed using a complementary variational technique. The dual formulation utilizes a minimum principle recently developed by Leitmann to convert the functional optimization problem into a parameter optimization problem.

  10. A Novel Tumor Antigen and Foxp3 Dual-Targeting Tumor Cell Vaccine Enhances the Immunotherapy in a Murine Model of Renal Cell Carcinoma

    DTIC Science & Technology

    2014-10-01

    DATES COVERED t 4. TITLE AND SUBTITLE A Novel Tumor Antigen and Foxp3 Dual-Targeting Tumor Cell Vaccine 5a. CONTRACT NUMBER Enhances the...past year I have generated Foxp3-over expressing RENCA cells, as the source of candidate dual targeting tumor cells vaccine . We have performed...controlled vaccine therapy in RENCA model in three different schedules. When applied in a pre- vaccine schedule, RENCA and RENCA Foxp3 tumor cell vaccine

  11. Fast Interrogation of Fiber Bragg Gratings with Electro-Optical Dual Optical Frequency Combs.

    PubMed

    Posada-Roman, Julio E; Garcia-Souto, Jose A; Poiana, Dragos A; Acedo, Pablo

    2016-11-26

    Optical frequency combs (OFC) generated by electro-optic modulation of continuous-wave lasers provide broadband coherent sources with high power per line and independent control of line spacing and the number of lines. In addition to their application in spectroscopy, they offer flexible and optimized sources for the interrogation of other sensors based on wavelength change or wavelength filtering, such as fiber Bragg grating (FBG) sensors. In this paper, a dual-OFC FBG interrogation system based on a single laser and two optical-phase modulators is presented. This architecture allows for the configuration of multimode optical source parameters such as the number of modes and their position within the reflected spectrum of the FBG. A direct read-out is obtained by mapping the optical spectrum onto the radio-frequency spectrum output of the dual-comb. This interrogation scheme is proposed for measuring fast phenomena such as vibrations and ultrasounds. Results are presented for dual-comb operation under optimized control. The optical modes are mapped onto detectable tones that are multiples of 0.5 MHz around a center radiofrequency tone (40 MHz). Measurements of ultrasounds (40 kHz and 120 kHz) are demonstrated with this sensing system. Ultrasounds induce dynamic strain onto the fiber, which generates changes in the reflected Bragg wavelength and, hence, modulates the amplitude of the OFC modes within the reflected spectrum. The amplitude modulation of two counterphase tones is detected to obtain a differential measurement proportional to the ultrasound signal.

  12. Dual-peak dose measurement for radiochromic films by a newly developed spectral microdensitometer

    SciTech Connect

    Lee, K.Y.; Fung, K.K.L.; Kwok, C.S.

    2005-06-15

    Radiochromic film (RCF) dosimetry is usually based on densitometric methods which use an analyzing light source of a fixed or a broad spectrum of wavelengths. These methods have not exploited the sensitivity of the dose response of the RCF otherwise attainable by using a light source with wavelengths peaked at the two absorption peaks in the absorption spectrum of the RCF. A new algorithm of dual-peak dose measurement for the RCF has been proposed in this paper to make use of these dual absorption peaks to achieve the maximum attainable sensitivity. This technique relies on the measurement of the transmittance of the RCF at the wavelength of the major and minor absorption peaks, respectively. The dual-peak dose measurement is accomplished with the aid of a novel spectral microdensitometer developed in our Institute. The microdensitometer utilizes a monochromator to provide a light source of which the wavelength can be matched precisely to the wavelength of the absorption peaks of the RCF. The doses obtained at these wavelengths are fed into a weighted objective function and an optimum dose is searched by minimizing the objective function to give the best estimate of the dose deposited on the film. An initial test shows that there is a good agreement between the estimated and actual dose deposited; and the maximum discrepancy was found to be less than 1%.

  13. Dual ion beam deposition of carbon films with diamondlike properties

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Swec, D. M.; Angus, J. C.

    1984-01-01

    A single and dual ion beam system was used to generate amorphous carbon films with diamond like properties. A methane/argon mixture at a molar ratio of 0.28 was ionized in the low pressure discharge chamber of a 30-cm-diameter ion source. A second ion source, 8 cm in diameter was used to direct a beam of 600 eV Argon ions on the substrates (fused silica or silicon) while the deposition from the 30-cm ion source was taking place. Nuclear reaction and combustion analysis indicate H/C ratios for the films to be 1.00. This high value of H/C, it is felt, allowed the films to have good transmittance. The films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Although the measured density of the films was approximately 1.8 gm/cu cm, a value lower than diamond, the films exhibited other properties that were relatively close to diamond. These films were compared with diamondlike films generated by sputtering a graphite target.

  14. 20 CFR 225.14 - Railroad Earnings Dual Benefit PIA.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true Railroad Earnings Dual Benefit PIA. 225.14 Section 225.14 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT... Annuities § 225.14 Railroad Earnings Dual Benefit PIA. (a) General. The Railroad Earnings Dual Benefit...

  15. Who Chooses Dual Language Education for Their Children and Why

    ERIC Educational Resources Information Center

    Parkes, Jay

    2008-01-01

    A survey of 724 families of dual language enrichment students in the South-west USA explored what kinds of families had chosen dual language education for their children and why. Of those parents who chose dual language for their children, 45.4% speak primarily English with their child, while 54.6% speak primarily Spanish. English-dominant parents…

  16. 20 CFR 225.14 - Railroad Earnings Dual Benefit PIA.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false Railroad Earnings Dual Benefit PIA. 225.14 Section 225.14 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT... Annuities § 225.14 Railroad Earnings Dual Benefit PIA. (a) General. The Railroad Earnings Dual Benefit...

  17. 20 CFR 225.14 - Railroad Earnings Dual Benefit PIA.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Railroad Earnings Dual Benefit PIA. 225.14 Section 225.14 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT... Annuities § 225.14 Railroad Earnings Dual Benefit PIA. (a) General. The Railroad Earnings Dual Benefit...

  18. 49 CFR 538.9 - Dual fuel vehicle incentive.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.9 Dual fuel vehicle incentive. The application of 49 U.S.C. 32905(b) and (d) to qualifying dual fuel vehicles... 49 Transportation 6 2014-10-01 2014-10-01 false Dual fuel vehicle incentive. 538.9 Section...

  19. 49 CFR 538.9 - Dual fuel vehicle incentive.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.9 Dual fuel vehicle incentive. The application of 49 U.S.C. 32905(b) and (d) to qualifying dual fuel vehicles... 49 Transportation 6 2012-10-01 2012-10-01 false Dual fuel vehicle incentive. 538.9 Section...

  20. 49 CFR 538.9 - Dual fuel vehicle incentive.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.9 Dual fuel vehicle incentive. The application of 49 U.S.C. 32905(b) and (d) to qualifying dual fuel vehicles... 49 Transportation 6 2013-10-01 2013-10-01 false Dual fuel vehicle incentive. 538.9 Section...

  1. 49 CFR 538.9 - Dual fuel vehicle incentive.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.9 Dual fuel vehicle incentive. The application of 49 U.S.C. 32905(b) and (d) to qualifying dual fuel vehicles... 49 Transportation 6 2010-10-01 2010-10-01 false Dual fuel vehicle incentive. 538.9 Section...

  2. 49 CFR 538.9 - Dual fuel vehicle incentive.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.9 Dual fuel vehicle incentive. The application of 49 U.S.C. 32905(b) and (d) to qualifying dual fuel vehicles... 49 Transportation 6 2011-10-01 2011-10-01 false Dual fuel vehicle incentive. 538.9 Section...

  3. Expanding Dual Enrollment: Increasing Postsecondary Access for All?

    ERIC Educational Resources Information Center

    Pretlow, Josh; Wathington, Heather D.

    2014-01-01

    This study investigated the dual enrollment outcomes associated with a 2005 policy change intended to expand dual enrollment participation in Virginia. Results indicated that overall access to and participation in dual enrollment courses increased following the policy change. However, data showed this increase was not uniform, and minority groups…

  4. 14 CFR 23.399 - Dual control system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Dual control system. 23.399 Section 23.399... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Control Surface and System Loads § 23.399 Dual control system. (a) Each dual control system must be designed to withstand the...

  5. 14 CFR 29.399 - Dual control system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Dual control system. 29.399 Section 29.399... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Control Surface and System Loads § 29.399 Dual control system. Each dual primary flight control system must be able to withstand the loads...

  6. 14 CFR 29.399 - Dual control system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Dual control system. 29.399 Section 29.399... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Control Surface and System Loads § 29.399 Dual control system. Each dual primary flight control system must be able to withstand the loads...

  7. 14 CFR 25.399 - Dual control system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Dual control system. 25.399 Section 25.399... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Control Surface and System Loads § 25.399 Dual control system. (a) Each dual control system must be designed for the pilots operating in opposition,...

  8. 14 CFR 23.399 - Dual control system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Dual control system. 23.399 Section 23.399... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Control Surface and System Loads § 23.399 Dual control system. (a) Each dual control system must be designed to withstand the...

  9. 14 CFR 27.399 - Dual control system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Dual control system. 27.399 Section 27.399... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Control Surface and System Loads § 27.399 Dual control system. Each dual primary flight control system must be designed to withstand the loads...

  10. 14 CFR 25.399 - Dual control system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Dual control system. 25.399 Section 25.399... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Control Surface and System Loads § 25.399 Dual control system. (a) Each dual control system must be designed for the pilots operating in opposition,...

  11. Crowd Sourcing.

    PubMed

    Baum, Neil

    2016-01-01

    The Internet has contributed new words and slang to our daily vernacular. A few terms, such as tweeting, texting, sexting, blogging, and googling, have become common in most vocabularies and in many languages, and are now included in the dictionary. A new buzzword making the rounds in industry is crowd sourcing, which involves outsourcing an activity, task, or problem by sending it to people or groups outside a business or a practice. Crowd sourcing allows doctors and practices to tap the wisdom of many instead of relying only on the few members of their close-knit group. This article defines "crowd sourcing," offers examples, and explains how to get started with this approach that can increase your ability to finish a task or solve problems that you don't have the time or expertise to accomplish.

  12. ION SOURCE

    DOEpatents

    Leland, W.T.

    1960-01-01

    The ion source described essentially eliminater the problem of deposits of nonconducting materials forming on parts of the ion source by certain corrosive gases. This problem is met by removing both filament and trap from the ion chamber, spacing them apart and outside the chamber end walls, placing a focusing cylinder about the filament tip to form a thin collimated electron stream, aligning the cylinder, slits in the walls, and trap so that the electron stream does not bombard any part in the source, and heating the trap, which is bombarded by electrons, to a temperature hotter than that in the ion chamber, so that the tendency to build up a deposit caused by electron bombardment is offset by the extra heating supplied only to the trap.

  13. Neutron source

    DOEpatents

    Cason, J.L. Jr.; Shaw, C.B.

    1975-10-21

    A neutron source which is particularly useful for neutron radiography consists of a vessel containing a moderating media of relatively low moderating ratio, a flux trap including a moderating media of relatively high moderating ratio at the center of the vessel, a shell of depleted uranium dioxide surrounding the moderating media of relatively high moderating ratio, a plurality of guide tubes each containing a movable source of neutrons surrounding the flux trap, a neutron shield surrounding one part of each guide tube, and at least one collimator extending from the flux trap to the exterior of the neutron source. The shell of depleted uranium dioxide has a window provided with depleted uranium dioxide shutters for each collimator. Reflectors are provided above and below the flux trap and on the guide tubes away from the flux trap.

  14. Dual-throat thruster thermal model

    NASA Technical Reports Server (NTRS)

    Ewen, R. L.; Obrien, C. J.; Matthews, L. W.

    1986-01-01

    The dual-throat engine is one of the dual nozzle engine concepts studied for advanced space transportation applications. It provides a thrust change and an in-flight area ratio change through the use of two concentric combustors with their throats arranged in series. Test results are presented for a dual throat thruster burning gaseous oxygen and hydrogen at primary (inner) chamber pressures from 380 to 680 psia. Heat flux profiles were obtained from calorimetric cooling channels in the inner nozzle, outer or secondary chamber and the tip of the inner nozzle. Data were obtained for two nozzle spacings over a chamber pressure ratio (secondary/primary) range of 0.45 to 0.83 with both chambers firing (Mode I). Fluxes near the end of the inner nozzle were significantly higher than in Mode II when only the inner chamber was fired, due to the flow separation and recirculation caused by the back pressure imposed by the secondary chamber. As the pressure ratio increased, these heat fluxes increased and the region of high heat flux relative to Mode II extended farther upstream. The use of the gaseous hydrogen bleed flow in the secondary chamber to control heat fluxes in the primary plume attachment region was investigated in Mode II testing. A thermal model of a dual throat thruster was developed and upgraded using the experimental data.

  15. Eliminating Barriers to Dual Enrollment in Oklahoma

    ERIC Educational Resources Information Center

    Roach, Rick; Gamez Vargas, Juanita; David, Kevin M.

    2015-01-01

    Policy, financial, and transportation barriers have limited participation in dual enrollment for marginalized (low-socioeconomic, first-generation, and ethnic minority) students in Oklahoma. This chapter presents a collaborative effort by education and community leaders that has successfully eliminated these barriers and increased the number of…

  16. Improved dual flow aluminum hydrogen peroxide battery

    SciTech Connect

    Marsh, C.; Licht, S.L.; Matthews, D.

    1993-11-30

    A novel dual flow battery configuration is provided comprising an aqueous hydrogen peroxide catholyte, an aqueous anolyte, a porous solid electrocatalyst capable of reducing said hydrogen peroxide and separating said anolyte, and an aluminum anode positioned within said anolyte. Separation of catholyte and anolyte chambers prevents hydrogen peroxide poisoning of the aluminum anode.

  17. Improved dual flow aluminum hydrogen peroxide battery

    NASA Astrophysics Data System (ADS)

    Marsh, Catherine; Licht, Stuart L.; Matthews, Donna

    1993-11-01

    A novel dual flow battery configuration is provided comprising an aqueous hydrogen peroxide catholyte, an aqueous anolyte, a porous solid electrocatalyst capable of reducing said hydrogen peroxide and separating said anolyte, and an aluminum anode positioned within said anolyte. Separation of catholyte and anolyte chambers prevents hydrogen peroxide poisoning of the aluminum anode.

  18. 45 CFR 63.35 - Dual compensation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 1 2012-10-01 2012-10-01 false Dual compensation. 63.35 Section 63.35 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION GRANT PROGRAMS ADMINISTERED BY THE... compensation. If a project staff member or consultant of one grantee is involved simultaneously in two or...

  19. 45 CFR 63.35 - Dual compensation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 1 2013-10-01 2013-10-01 false Dual compensation. 63.35 Section 63.35 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION GRANT PROGRAMS ADMINISTERED BY THE... compensation. If a project staff member or consultant of one grantee is involved simultaneously in two or...

  20. 45 CFR 63.35 - Dual compensation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 1 2014-10-01 2014-10-01 false Dual compensation. 63.35 Section 63.35 Public Welfare Department of Health and Human Services GENERAL ADMINISTRATION GRANT PROGRAMS ADMINISTERED BY THE... compensation. If a project staff member or consultant of one grantee is involved simultaneously in two or...

  1. 45 CFR 63.35 - Dual compensation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Dual compensation. 63.35 Section 63.35 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION GRANT PROGRAMS ADMINISTERED BY THE... compensation. If a project staff member or consultant of one grantee is involved simultaneously in two or...

  2. 45 CFR 63.35 - Dual compensation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 1 2011-10-01 2011-10-01 false Dual compensation. 63.35 Section 63.35 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION GRANT PROGRAMS ADMINISTERED BY THE... compensation. If a project staff member or consultant of one grantee is involved simultaneously in two or...

  3. Equality by Default: Women in Dual Roles

    ERIC Educational Resources Information Center

    Campbell, Ena

    1978-01-01

    The struggle for an Equal Rights Amendment (ERA) to the American Constitution is one of the most controversial issues of this era. Discusses the changing role of women amidst a fast-changing society, the styles of those opposing the women's revolution, the debate over women as persons, women in dual roles, and the implications of ERA for the world…

  4. Online Dual Credit Mathematics for Rural Schools

    ERIC Educational Resources Information Center

    Harris, Roy Joe; Stovall, Sarah T.

    2013-01-01

    Students from small rural schools (class 1A, 2A, and 3A) historically have not had access to dual credit courses for several reasons including distance from a college campus, affordability, and district teaching strength. In an effort to address these problems and to begin the college experience sooner, a new program was developed by the…

  5. Dual Language Education. Bilingual Education and Bilingualism.

    ERIC Educational Resources Information Center

    Lindholm-Leary, Kathryn J.

    Dual language education is a programme that combines language minority and language majority students for instruction through two languages. This book provides the conceptual background for the programme and discusses major implementation issues. Research findings summarize language proficiency and achievement outcomes from 8000 students at 20…

  6. Student Perceptions of Dual-Listed Courses

    ERIC Educational Resources Information Center

    Balassiano, Katia; Rosentrater, Kurt A.; Marcketti, Sara B.

    2014-01-01

    Academic departments regularly offer dual-listed courses in which one course has two course numbers, yet are taught in the same place, at the same time, by a single instructor, and in one department to undergraduate and graduate students. While universities discourage their use by subjecting such courses to more rigorous approval processes,…

  7. Coupled dual loop absorption heat pump

    DOEpatents

    Sarkisian, Paul H.; Reimann, Robert C.; Biermann, Wendell J.

    1985-01-01

    A coupled dual loop absorption system which utilizes two separate complete loops. Each individual loop operates at three temperatures and two pressures. This low temperature loop absorber and condenser are thermally coupled to the high temperature loop evaporator, and the high temperature loop condenser and absorber are thermally coupled to the low temperature generator.

  8. Workplace Learning in Dual Higher Professional Education

    ERIC Educational Resources Information Center

    Poortman, Cindy L.; Reenalda, Marloes; Nijhof, Wim J.; Nieuwenhuis, Loek F. M.

    2014-01-01

    Workplace learning is considered an effective strategy for the development of vocation, career and professional identity. Dual training programs, in which learning at a vocational school and learning at work in a company are combined, are seen as strong carriers for skill formation processes. In this study we explore workplace learning in dual…

  9. Dual Diagnosis in the United States.

    ERIC Educational Resources Information Center

    Reiss, Steven

    1988-01-01

    Goals of the dual diagnosis movement in the U.S. have been to increase recognition of the mental health disorders of mentally retarded people, develop appropriate assessment techniques, establish both residential and outpatient services, and improve research by clarifying the roles of federal funding agencies. (JDD)

  10. The Gentrification of Dual Language Education

    ERIC Educational Resources Information Center

    Valdez, Verónica E.; Freire, Juan A.; Delavan, M. Garrett

    2016-01-01

    Utah's dual language education (DL) initiative, officially introduced in 2007 and backed by unique state-level planning, is touted as a new "mainstreaming" of DL and is sparking interest across the U.S. Using a critical language policy lens and a mixed method approach, we asked which student groups were positioned discursively and…

  11. Success and Challenges in Dual Language Education

    ERIC Educational Resources Information Center

    Lindholm-Leary, Kathryn

    2012-01-01

    This article presents research that highlights the success of dual language education for student participants, both native English speakers and English language learners, from a variety of demographic backgrounds at both the elementary and secondary levels. However, there are a number of challenges that can impede the quality of implementation in…

  12. Some Final Reflections on Dual Audio Television.

    ERIC Educational Resources Information Center

    Borton, Terry; And Others

    The Philadelphia City Schools engaged in a four-year program to develop and test dual audio television, a way to help children learn more from the massive amount of time they spend watching commercial television. The format consisted of an instructional radio broadcast that accompanied popular television shows and attempted to clarify and amplify…

  13. Commentary on the Dual-Career Family.

    ERIC Educational Resources Information Center

    Tinsley, Diane J.

    1987-01-01

    Recommends, in dual-career family research, describing models that are general enough to apply to individuals with various lifestyles and taking more of a family systems perspective. Recognition and rewards for enhanced family relationships and goals met would be appropriate. Recommends Gilbert and Rachlin's triple helix model which notes the…

  14. Dual Audio TV Instruction: A Broadcast Experiment.

    ERIC Educational Resources Information Center

    Borton, Terry; And Others

    An experiment assessed the potential effectiveness of "dual audio television instruction" (DATI) as a mass education medium. The DATI consisted of a radio program heard by children while they watched television shows. The audio instructor did not talk when the television characters spoke, but used the "quiet" times to help with…

  15. Dual-Retrieval Models and Neurocognitive Impairment

    ERIC Educational Resources Information Center

    Brainerd, C. J.; Reyna, V. F.; Gomes, C. F. A.; Kenney, A. E.; Gross, C. J.; Taub, E. S.; Spreng, R. N.

    2014-01-01

    Advances in dual-retrieval models of recall make it possible to use clinical data to test theoretical hypotheses about mild cognitive impairment (MCI) and Alzheimer's dementia (AD), the most common forms of neurocognitive impairment. Hypotheses about the nature of the episodic memory declines in these diseases, about decline versus sparing of…

  16. Dual-Rate Transmission Reduces Weather Effects

    NASA Technical Reports Server (NTRS)

    Posner, E. C.

    1984-01-01

    Scheme ensures maximum data received on average. Dual-rate scheme for maximizing data returned during spacecraft mission, adaptable, as is or with modifications, to high-frequency terrestrial data transmission. Data rate fixed in advance at minimum value guarantees reasonable prospect of success during bad weather. Dualrate strategy yields net data rate 2.5 times best achievable with single transmission rate.

  17. Dual-code quantum computation model

    NASA Astrophysics Data System (ADS)

    Choi, Byung-Soo

    2015-08-01

    In this work, we propose the dual-code quantum computation model—a fault-tolerant quantum computation scheme which alternates between two different quantum error-correction codes. Since the chosen two codes have different sets of transversal gates, we can implement a universal set of gates transversally, thereby reducing the overall cost. We use code teleportation to convert between quantum states in different codes. The overall cost is decreased if code teleportation requires fewer resources than the fault-tolerant implementation of the non-transversal gate in a specific code. To analyze the cost reduction, we investigate two cases with different base codes, namely the Steane and Bacon-Shor codes. For the Steane code, neither the proposed dual-code model nor another variation of it achieves any cost reduction since the conventional approach is simple. For the Bacon-Shor code, the three proposed variations of the dual-code model reduce the overall cost. However, as the encoding level increases, the cost reduction decreases and becomes negative. Therefore, the proposed dual-code model is advantageous only when the encoding level is low and the cost of the non-transversal gate is relatively high.

  18. Dual Enrollment Credit and College Readiness

    ERIC Educational Resources Information Center

    Ganzert, Bart

    2014-01-01

    This causal-comparative study researched the effects of dual enrollment and Huskins Bill course experience on traditional-age North Carolina community college students. The study examined course effects on academic success and graduation rate using quantitative statistical measures including parametric and nonparametric means comparisons. The…

  19. RADIATION SOURCES

    DOEpatents

    Brucer, M.H.

    1958-04-15

    A novel long-lived source of gamma radiation especially suitable for calibration purposes is described. The source of gamma radiation is denoted mock iodine131, which comprises a naixture of barium-133 and cesium-137. The barium and cesium are present in a barium-cesium ratio of approximately 5.7/1 to 14/1, uniformly dispersed in an ion exchange resin and a filter surrounding the resin comprised of a material of atomic number below approximately 51, and substantially 0.7 to 0.9 millimeter thick.

  20. NEUTRON SOURCE

    DOEpatents

    Reardon, W.A.; Lennox, D.H.; Nobles, R.G.

    1959-01-13

    A neutron source of the antimony--beryllium type is presented. The source is comprised of a solid mass of beryllium having a cylindrical recess extending therein and a cylinder containing antimony-124 slidably disposed within the cylindrical recess. The antimony cylinder is encased in aluminum. A berylliunn plug is removably inserted in the open end of the cylindrical recess to completely enclose the antimony cylinder in bsryllium. The plug and antimony cylinder are each provided with a stud on their upper ends to facilitate handling remotely.

  1. Modular synthesis of a dual metal-dual semiconductor nano-heterostructure

    DOE PAGES

    Amirav, Lilac; Oba, Fadekemi; Aloni, Shaul; ...

    2015-04-29

    Reported is the design and modular synthesis of a dual metal-dual semiconductor heterostructure with control over the dimensions and placement of its individual components. Analogous to molecular synthesis, colloidal synthesis is now evolving into a series of sequential synthetic procedures with separately optimized steps. Here we detail the challenges and parameters that must be considered when assembling such a multicomponent nanoparticle, and their solutions.

  2. A dual cone-beam CT system for image guided radiotherapy: Initial performance characterization

    SciTech Connect

    Li Hao; Bowsher, James; Yin Fangfang; Giles, William

    2013-02-15

    Purpose: The purpose of this study is to evaluate the performance of a recently developed benchtop dual cone-beam computed tomography (CBCT) system with two orthogonally placed tube/detector sets. Methods: The benchtop dual CBCT system consists of two orthogonally placed 40 Multiplication-Sign 30 cm flat-panel detectors and two conventional x-ray tubes with two individual high-voltage generators sharing the same rotational axis. The x-ray source to detector distance is 150 cm and x-ray source to rotational axis distance is 100 cm for both subsystems. The objects are scanned through 200 Degree-Sign of rotation. The dual CBCT system utilized 110 Degree-Sign of projection data from one detector and 90 Degree-Sign from the other while the two individual single CBCTs utilized 200 Degree-Sign data from each detector. The system performance was characterized in terms of uniformity, contrast, spatial resolution, noise power spectrum, and CT number linearity. The uniformities, within the axial slice and along the longitudinal direction, and noise power spectrum were assessed by scanning a water bucket; the contrast and CT number linearity were measured using the Catphan phantom; and the spatial resolution was evaluated using a tungsten wire phantom. A skull phantom and a ham were also scanned to provide qualitative evaluation of high- and low-contrast resolution. Each measurement was compared between dual and single CBCT systems. Results: Compared to single CBCT, the dual CBCT presented: (1) a decrease in uniformity by 1.9% in axial view and 1.1% in the longitudinal view, as averaged for four energies (80, 100, 125, and 150 kVp); (2) comparable or slightly better contrast (0{approx}25 HU) for low-contrast objects and comparable contrast for high-contrast objects; (3) comparable spatial resolution; (4) comparable CT number linearity with R{sup 2}{>=} 0.99 for all four tested energies; (5) lower noise power spectrum in magnitude. Dual CBCT images of the skull phantom and the

  3. Dual Arm Work Module Development and Appplications

    SciTech Connect

    Noakes, M.W.

    1999-04-25

    The dual arm work module (DAWM) was developed at Oak Ridge National Laboratory (ORNL) by the Robotics Technology Development Program (RTDP) as a development test bed to study issues related to dual arm manipulation, including platform cotilguration, controls, automation, operations, and tooling. The original platform was based on two Schilling Titan II manipulators mounted to a 5-degree-of- freedom (DOF) base fabricated by RedZone Robotics, Inc. The 5-DOF articulation provided a center torso rotation, linear actuation to change the separation between the arms, and arm base rotation joints to provide "elbows up," elbows down," or "elbows out" orientation. A series of tests were conducted on operations, tooling, and task space scene analysis (TSSA)-driven robotics for overhead transporter- mounted and crane hook-deployed scenarios. A concept was developed for DAWM deployment from a large remote work vehicle, but the project was redirected to support dismantlement of the Chicago Pile #5 (CP-5) reactor at Argonne National Laboratory in fiscal year (FY) 1997. Support of CP-5 required a change in focus of the dual arm technology from that of a development test bed to a system focussed for a specific end user. ORNL teamed with the Idaho National Environmental ,Engineering Laboratory, Sandia National Laboratory, and the Savannah River Technology Center to deliver a crane-deployed derivative of the DAWM, designated the dual arm work platform (DAWP). RTDP staff supported DAWP at CP-5 for one FY; Argonne staff continued operation through to dismantlement of the reactor internals. Lessons learned from this interaction were extensive. Beginning in FY 1999, dual arm development activities are again being pursued in the context of those lessons learned. This paper describes the progression of philosophy of the DAWM from initial test bed to lessons learned through interaction at CP-5 and to the present investigation of telerobotic assist of teleoperation and TSSA- driven robotics.

  4. Antipsychotic Treatment of Adolescent Dual Diagnosis Patients

    PubMed Central

    Price, Scott A.; Brahm, Nancy C.

    2011-01-01

    BACKGROUND A diagnosis of schizophrenia requires development of a pharmacotherapy regimen that balances many factors in the therapeutic decision-making process. Patient age and the presence or absence of comorbid chemical dependency represent two factors. Comorbid chemical dependency can have a profound impact on the successful treatment of schizophrenia, making patients with dual diagnoses of schizophrenia and chemical dependence a uniquely challenging population. There is little information regarding treatment of schizophrenia and chemical dependence in the pediatric population. Existing data from pediatric and adult populations may facilitate a well-guided and knowledgeable approach to treating pediatric dual diagnosis patients. METHODS A review of the literature for medication trials evaluating antipsychotic medication used to treat schizophrenia in childhood and adolescence as well as antipsychotic use in the treatment of the dual diagnoses of schizophrenia and chemical dependence was done. Databases for Ovid MEDLINE, PubMed, and PsycInfo were searched using the terms “addiction,” “adolescence,” “childhood,” “dual diagnosis,” “schizophrenia,” and “substance abuse.” Results were limited to English-language articles. RESULTS Seven articles were identified related to psychotic disorders and substance abuse in pediatric populations. Psychosis measurement instruments included the Brief Psychiatric Rating Scale, Positive and Negative Syndrome Scale, and Clinical Global Impression. Mean improvements were insignificant in most cases. Medication trials included clozapine, olanzapine, risperidone, and molindone. Trial safety concerns included metabolic effects, increased prolactin levels, and akathisia. One study with random assignment to olanzapine was discontinued early because of substantial weight gain without evidence of superior efficacy. Clozapine treatment was associated with more adverse drug events. CONCLUSION There is a great need for

  5. A dual-sided coded-aperture radiation detection system

    NASA Astrophysics Data System (ADS)

    Penny, R. D.; Hood, W. E.; Polichar, R. M.; Cardone, F. H.; Chavez, L. G.; Grubbs, S. G.; Huntley, B. P.; Kuharski, R. A.; Shyffer, R. T.; Fabris, L.; Ziock, K. P.; Labov, S. E.; Nelson, K.

    2011-10-01

    We report the development of a large-area, mobile, coded-aperture radiation imaging system for localizing compact radioactive sources in three dimensions while rejecting distributed background. The 3D Stand-Off Radiation Detection System (SORDS-3D) has been tested at speeds up to 95 km/h and has detected and located sources in the millicurie range at distances of over 100 m. Radiation data are imaged to a geospatially mapped world grid with a nominal 1.25- to 2.5-m pixel pitch at distances out to 120 m on either side of the platform. Source elevation is also extracted. Imaged radiation alarms are superimposed on a side-facing video log that can be played back for direct localization of sources in buildings in urban environments. The system utilizes a 37-element array of 5×5×50 cm 3 cesium-iodide (sodium) detectors. Scintillation light is collected by a pair of photomultiplier tubes placed at either end of each detector, with the detectors achieving an energy resolution of 6.15% FWHM (662 keV) and a position resolution along their length of 5 cm FWHM. The imaging system generates a dual-sided two-dimensional image allowing users to efficiently survey a large area. Imaged radiation data and raw spectra are forwarded to the RadioNuclide Analysis Kit (RNAK), developed by our collaborators, for isotope ID. An intuitive real-time display aids users in performing searches. Detector calibration is dynamically maintained by monitoring the potassium-40 peak and digitally adjusting individual detector gains. We have recently realized improvements, both in isotope identification and in distinguishing compact sources from background, through the installation of optimal-filter reconstruction kernels.

  6. Preliminary experimental investigation of a dual-band relativistic backward wave oscillator with dual beams

    SciTech Connect

    Wang Ting; Qian Baoliang; Zhang Jiande; Zhang Xiaoping; Cao Yibing; Zhang Qiang

    2011-01-15

    A dual-band relativistic backward wave oscillator with dual electron beams generating C-band and X-band microwaves is investigated experimentally. The frequencies, powers, and radiation patterns of the dual-band microwaves are measured. With the diode voltage of 657 kV and the total beam current of 14 kA guided by a magnetic field of about 1.7 T, the dual-band microwaves are generated with dominant frequencies of 4.58 and 8.30 GHz close to the results from the particle-in-cell simulation. The powers of the C-band and X-band microwaves are 520 and 113 MW, respectively. The effects of variations in the guiding magnetic field and diode voltage on the powers of the dual-band microwaves are presented and discussed. The radiation patterns of the dual-band microwaves from the radiating antenna are tested both corresponding to a TM{sub 01} mode and the independency of the operation processes of them is discussed.

  7. Dual Location Dual Reduction/Photoresponsive Block Copolymer Micelles: Disassembly and Synergistic Release.

    PubMed

    Sun, Tongbing; Li, Puzhen; Oh, Jung Kwon

    2015-10-01

    Self-assembled micellar systems designed with multiple stimuli-responsive degradation have been considered as effective candidates for polymer-based delivery systems exhibiting enhanced/controlled release. However, most conventional approaches involve the incorporation of single, dual, or multiple cleavable linkages positioned at single locations, as in hydrophobic cores or at core/corona interfaces. Herein, a novel dual location dual reduction and photoresponsive block copolymer containing a disulfide linkage at the block junction and pendant o-nitrobenzyl thioether (NBS) groups in the hydrophobic methacrylate block (PEG-ss-PhvM) are reported, which are synthesized by a combination of controlled radical polymerization and facile coupling reaction. The amphiphilic design of the PEG-ss-PhvM enables the formation of self-assembled micellar aggregates with disulfides at the core/corona interfaces and pendant photocleavable NBS groups in the hydrophobic cores. The dual cleavable linkages respond to each stimulus (GSH or light), exhibiting enhanced release; further to a combination of dual locational stimuli, promoting synergistic release at dual locations.

  8. Dual-energy micro-CT imaging for differentiation of iodine- and gold-based nanoparticles

    NASA Astrophysics Data System (ADS)

    Badea, C. T.; Johnston, S. M.; Qi, Y.; Ghaghada, K.; Johnson, G. A.

    2011-03-01

    Spectral CT imaging is expected to play a major role in the diagnostic arena as it provides material decomposition on an elemental basis. One fascinating possibility is the ability to discriminate multiple contrast agents targeting different biological sites. We investigate the feasibility of dual energy micro-CT for discrimination of iodine (I) and gold (Au) contrast agents when simultaneously present in the body. Simulations and experiments were performed to measure the CT enhancement for I and Au over a range of voltages from 40-to-150 kVp using a dual source micro-CT system. The selected voltages for dual energy micro-CT imaging of Au and I were 40 kVp and 80 kVp. On a massconcentration basis, the relative average enhancement of Au to I was 2.75 at 40 kVp and 1.58 at 80 kVp. We have demonstrated the method in a preclinical model of colon cancer to differentiate vascular architecture and extravasation. The concentration maps of Au and I allow quantitative measure of the bio-distribution of both agents. In conclusion, dual energy micro-CT can be used to discriminate probes containing I and Au with immediate impact in pre-clinical research.

  9. Real-time, closed-loop dual-wavelength optical polarimetry for glucose monitoring

    PubMed Central

    Malik, Bilal H.; Coté, Gerard L.

    2010-01-01

    The development of a real-time, dual-wavelength optical polarimetric system to ultimately probe the aqueous humor glucose concentrations as a means of noninvasive diabetic glucose monitoring is the long-term goal of this research. The key impact of the work is the development of an approach for the reduction of the time-variant corneal birefringence due to motion artifact, which is still a limiting factor preventing the realization of such a device. Our dual-wavelength approach utilizes real-time, closed-loop feedback that employs a classical three-term feedback controller and efficiently reduces the effect of motion artifact that appears as a common noise source for both wavelengths. In vitro results are shown for the open-loop system, and although the dual-wavelength system helps to reduce the noise, it is shown that closed-loop control is necessary to bring the noise down to a sufficient level for physiological monitoring. Specifically, in vitro measurement results with the closed-loop dual-wavelength approach demonstrate a sensitivity of 12.8 mg∕dl across the physiologic glucose range in the presence of time-variant test cell birefringence. Overall, it is shown that this polarimetric system has the potential to be used as a noninvasive measure of glucose for diabetes. PMID:20210476

  10. A Candidate Dual Active Galactic Nucleus at z = 1.175

    NASA Astrophysics Data System (ADS)

    Barrows, R. Scott; Stern, Daniel; Madsen, Kristin; Harrison, Fiona; Assef, Roberto J.; Comerford, Julia M.; Cushing, Michael C.; Fassnacht, Christopher D.; Gonzalez, Anthony H.; Griffith, Roger; Hickox, Ryan; Kirkpatrick, J. Davy; Lagattuta, David J.

    2012-01-01

    The X-ray source CXOXBJ142607.6+353351 (CXOJ1426+35), which was identified in a 172 ks Chandra image in the Boötes field, shows double-peaked rest-frame optical/UV emission lines, separated by 0farcs69 (5.5 kpc) in the spatial dimension and by 690 km s-1 in the velocity dimension. The high excitation lines and emission line ratios indicate both systems are ionized by an active galactic nucleus (AGN) continuum, and the double-peaked profile resembles that of candidate dual AGNs. At a redshift of z = 1.175, this source is the highest redshift candidate dual AGN yet identified. However, many sources have similar emission line profiles for which other interpretations are favored. We have analyzed the substantial archival data available in this field as well as acquired near-infrared (NIR) adaptive optics (AO) imaging and NIR slit spectroscopy. The X-ray spectrum is hard, implying a column density of several 1023 cm-2. Though heavily obscured, the source is also one of the brightest in the field, with an absorption-corrected 2-10 keV luminosity of ~1045 erg s-1. Outflows driven by an accretion disk may produce the double-peaked lines if the central engine accretes near the Eddington limit. However, we may be seeing the narrow line regions of two AGNs following a galactic merger. While the AO image reveals only a single source, a second AGN would easily be obscured by the significant extinction inferred from the X-ray data. Understanding the physical processes producing the complex emission line profiles seen in CXOJ1426+35 and related sources is important for interpreting the growing population of dual AGN candidates.

  11. Superluminal Sources

    NASA Astrophysics Data System (ADS)

    Vermeulen, R. C.

    1995-12-01

    Predictions for the apparent velocity statistics under simple beaming models are presented and compared to the observations. The potential applications for tests of unification models and for cosmology (source counts, measurements of the Hubble constant H_0 and the deceleration parameter q_0) are discussed. First results from a large homogeneous survey are presented. The data do not show compelling evidence for the existence of intrinsically different populations of galaxies, BL Lacertae objects, or quasars. Apparent velocities βapp in the range 1-5 h-1, where h = H_0/100 km.s-1.Mpc-1 [1 megaparsec (Mpc) = 3.09 x 1022 m], occur with roughly equal frequency; higher values, up to βapp = 10 h-1, are rather more scarce than appeared to be the case from earlier work, which evidently concentrated on sources that are not representative of the general population. The βapp distribution suggests that there might be a skewed distribution of Lorentz factors over the sample, with a peak at γ_b ≈ 2 h-1 and a tail up to at least γ_b ≈ 10 h-1. There appears to be a clearly rising upper envelope to the βapp distribution when plotted as a function of observed 5-GHz luminosity; a combination of source counts and the apparent velocity statistics in a larger sample could provide much insight into the properties of radio jet sources.

  12. Terahertz sources.

    PubMed

    Shumyatsky, Pavel; Alfano, Robert R

    2011-03-01

    We present an overview and history of terahertz (THz) sources for readers of the biomedical and optical community for applications in physics, biology, chemistry, medicine, imaging, and spectroscopy. THz low-frequency vibrational modes are involved in many biological, chemical, and solid state physical processes.

  13. Dual synchronization based on two different chaotic systems

    NASA Astrophysics Data System (ADS)

    Ning, Di; Lu, Jun-An; Han, Xiuping

    2007-09-01

    In this paper, we improve and extend the works of Liu and Davids [Dual synchronization of chaos, Phys. Rev. E 61 (2000) 2176-2179] which only introduce the dual synchronization of 1-D discrete chaotic systems. The dual synchronization of two different 3-D continuous chaotic systems, Lorenz systems and Rossler systems, is discussed. And a sufficient condition of dual synchronization about the two different chaotic systems is obtained. Theories and numerical simulations show the possibility of dual synchronization and the effectiveness of the method.

  14. Using a Borated Panel to Form a Dual Neutron-Gamma Detector

    SciTech Connect

    Scott Wilde; Raymond Keegan

    2008-06-20

    A borated polyethylene plane placed between a neutron source and a gamma spectrometer is used to form a dual neutron-gamma detection system. The polyethylene thermalizes the source neutrons so that they are captured by {sup 10}B to produce a flux of 478 keV gamma-rays that radiate from the plane. This results in a buildup of count rate in the detector over that from a disk of the same diameter as the detector crystal (same thickness as the panel). Radiation portal systems are a potential application of this technique.

  15. ION SOURCE

    DOEpatents

    Brobeck, W.M.

    1959-04-14

    This patent deals with calutrons and more particularly to an arrangement therein whereby charged bottles in a calutron source unit may be replaced without admitting atmospheric air to the calutron vacuum chamber. As described, an ion unit is disposed within a vacuum tank and has a reservoir open toward a wall of the tank. A spike projects from thc source into the reservoir. When a charge bottle is placed in the reservoir, the spike breaks a frangible seal on the bottle. After the contents of the bottle are expended the bottle may be withdrawn and replaced with another charge bottle by a varuum lock arrangement in conjunction with an arm for manipulating the bottle.

  16. Ion source

    DOEpatents

    Brobeck, W. M.

    1959-04-14

    This patent deals with calutrons and more particularly to an arrangement therein whereby charged bottles in a calutron source unit may be replaced without admitting atmospheric air to the calutron vacuum chamber. As described, an ion unit is disposed within a vacuum tank and has a reservoir open toward a wall of the tank. A spike projects from the source into the reservoir. When a charge bottle is placed in the reservoir, the spike breaks a frangible seal on the bottle. After the contents of the bottle are expended the bottle may be withdrawn and replaced with another charge bottle by a vacuum lock arrangement in conjunction with an arm for manipulating the bottle.

  17. ION SOURCE

    DOEpatents

    Blue, C.W.; Luce, J.S.

    1960-07-19

    An ion source is described and comprises an arc discharge parallel to the direction of and inside of a magnetic field. an accelerating electrode surrounding substantially all of the discharge except for ion exit apertures, and means for establishing an electric field between that electrode and the arc discharge. the electric field being oriented at an acute angle to the magnetic field. Ions are drawn through the exit apertures in the accelrating electrcde in a direction substantially divergent to the direction of the magnetic field and so will travel in a spiral orbit along the magnetic field such that the ions will not strike the source at any point in their orbit within the magnetic field.

  18. ION SOURCE

    DOEpatents

    Bell, W.A. Jr.; Love, L.O.; Prater, W.K.

    1958-01-28

    An ion source is presented capable of producing ions of elements which vaporize only at exceedingly high temperatures, i.e.,--1500 degrees to 3000 deg C. The ion source utilizes beams of electrons focused into a first chamber housing the material to be ionized to heat the material and thereby cause it to vaporize. An adjacent second chamber receives the vaporized material through an interconnecting passage, and ionization of the vaporized material occurs in this chamber. The ionization action is produced by an arc discharge sustained between a second clectron emitting filament and the walls of the chamber which are at different potentials. The resultant ionized material egresses from a passageway in the second chamber. Using this device, materials which in the past could not be processed in mass spectometers may be satisfactorily ionized for such applications.

  19. Dual Phase Membrane for High temperature CO2 Separation

    SciTech Connect

    Jerry Y.S. Lin; Matthew Anderson

    2005-12-01

    Research in the previous years in this project found that stainless steel supports are oxidized during high temperature, dual phase membrane separation of carbon dioxide (with oxygen). Consequently, a new material has been sought to alleviate the problems with oxidation. Lanthanum cobaltite oxide is a suitable candidate for the support material in the dual phase membrane due to its oxidation resistance and electronic conductivity. Porous lanthanum cobaltite membranes were prepared via the citrate method, using nitrate metal precursors as the source of La, Sr, Co and Fe. The material was prepared and ground into a powder, which was subsequently pressed into disks for sintering at 900 C. Conductivity measurements were evaluated using the four-probe DC method. Support pore size was determined by helium permeation. Conductivity of the lanthanum cobaltite material was found to be at a maximum of 0.1856 S/cm at 550 C. The helium permeance of the lanthanum cobaltite membranes for this research was on the order of 10{sup -6} moles/m{sup 2} {center_dot} Pa {center_dot} s, proving that the membranes are porous after sintering at 900 C. The average pore size based on steady state helium permeance measurements was found to be between 0.37 and 0.57 {micro}m. The lanthanum cobaltite membranes have shown to have desired porosity, pore size and electric conductivity as the support for the dual-phase membranes. Molten carbonate was infiltrated to the pores of lanthanum cobaltite membranes support. After infiltration with molten carbonate, the helium permeance of the membranes decreased by three orders of magnitude to 10{sup -9} moles/m{sup 2} {center_dot} Pa {center_dot} s. This number, however, is one order of magnitude larger than the room temperate permeance of the stainless steel supports after infiltration with molten carbonate. Optimization of the dip coating process with molten carbonate will be evaluated to determine if lower permeance values can be obtained with the

  20. Adaptive upscaling with the dual mesh method

    SciTech Connect

    Guerillot, D.; Verdiere, S.

    1997-08-01

    The objective of this paper is to demonstrate that upscaling should be calculated during the flow simulation instead of trying to enhance the a priori upscaling methods. Hence, counter-examples are given to motivate our approach, the so-called Dual Mesh Method. The main steps of this numerical algorithm are recalled. Applications illustrate the necessity to consider different average relative permeability values depending on the direction in space. Moreover, these values could be different for the same average saturation. This proves that an a priori upscaling cannot be the answer even in homogeneous cases because of the {open_quotes}dynamical heterogeneity{close_quotes} created by the saturation profile. Other examples show the efficiency of the Dual Mesh Method applied to heterogeneous medium and to an actual field case in South America.

  1. Harmonic generation with a dual frequency pulse.

    PubMed

    Keravnou, Christina P; Averkiou, Michalakis A

    2014-05-01

    Nonlinear imaging was implemented in commercial ultrasound systems over the last 15 years offering major advantages in many clinical applications. In this work, pulsing schemes coupled with a dual frequency pulse are presented. The pulsing schemes considered were pulse inversion, power modulation, and power modulated pulse inversion. The pulse contains a fundamental frequency f and a specified amount of its second harmonic 2f. The advantages and limitations of this method were evaluated with both acoustic measurements of harmonic generation and theoretical simulations based on the KZK equation. The use of two frequencies in a pulse results in the generation of the sum and difference frequency components in addition to the other harmonic components. While with single frequency pulses, only power modulation and power modulated pulse inversion contained odd harmonic components, with the dual frequency pulse, pulse inversion now also contains odd harmonic components.

  2. Automatic differentiation using vectorized hyper dual numbers

    NASA Astrophysics Data System (ADS)

    Swaroop, Kshitiz

    Sensitivity analysis is a method to measure the change in a dependent variable with respect to one or more independent variables with uses including optimization, design analysis and risk modeling. Conventional methods like finite difference suffer from both truncation, subtraction errors and cannot be used to simultaneously calculate derivatives of an output with respect to multiple inputs (commonly seen in optimization problems). Automatic Differentiation tackles all these issues successfully allowing us to calculate derivatives of any variable with respect to the independent variables in a computer program up to machine precision without any significant user input. Vectorized Hyper Dual Numbers, an extension of Hyper Dual Numbers, which allows the user to automatically calculate both the Hessian and derivative along with the function evaluation is developed for this thesis. The method is then used for the sizing and layup of a composite wind turbine blade as a proof of concept.

  3. Dual motion valve with single motion input

    NASA Technical Reports Server (NTRS)

    Belew, Robert (Inventor)

    1987-01-01

    A dual motion valve includes two dual motion valve assemblies with a rotary input which allows the benefits of applying both rotary and axial motion to a rotary sealing element with a plurality of ports. The motion of the rotary sealing element during actuation provides axial engagement of the rotary sealing element with a stationary valve plate which also has ports. Fluid passages are created through the valve when the ports of the rotary sealing element are aligned with the ports of the stationary valve plate. Alignment is achieved through rotation of the rotary sealing element with respect to the stationary valve plate. The fluid passages provide direct paths which minimize fluid turbulence created in the fluid as it passes through the valve.

  4. Dual fuel gradients in uranium silicide plates

    SciTech Connect

    Pace, B.W.

    1997-08-01

    Babcock & Wilcox has been able to achieve dual gradient plates with good repeatability in small lots of U{sub 3}Si{sub 2} plates. Improvements in homogeneity and other processing parameters and techniques have allowed the development of contoured fuel within the cladding. The most difficult obstacles to overcome have been the ability to evaluate the bidirectional fuel loadings in comparison to the perfect loading model and the different methods of instilling the gradients in the early compact stage. The overriding conclusion is that to control the contour of the fuel, a known relationship between the compact, the frames and final core gradient must exist. Therefore, further development in the creation and control of dual gradients in fuel plates will involve arriving at a plausible gradient requirement and building the correct model between the compact configuration and the final contoured loading requirements.

  5. AdS duals of matrix strings

    NASA Astrophysics Data System (ADS)

    Morales, Jose F.; Samtleben, Henning

    2003-06-01

    We review recent work on the holographic duals of type II and heterotic matrix string theories described by warped AdS3 supergravities. In particular, we compute the spectra of Kaluza-Klein primaries for type I, II supergravities on warped AdS3 × S7 and match them with the primary operators in the dual two-dimensional gauge theories. The presence of non-trivial warp factors and dilaton profiles requires a modification of the familiar dictionary between masses and 'scaling' dimensions of fields and operators. We present these modifications for the general case of domain wall/QFT correspondences between supergravities on warped AdSd+1 × Sq geometries and super Yang-Mills theories with 16 supercharges.

  6. Dual-rail optical gradient echo memory

    NASA Astrophysics Data System (ADS)

    Higginbottom, D. B.; Geng, J.; Campbell, G. T.; Hosseini, M.; Cao, M. T.; Sparkes, B. M.; Bernu, J.; Robins, N. P.; Lam, P. K.; Buchler, B. C.

    2015-09-01

    We introduce a scheme for the parallel storage of frequency separated signals in an optical memory and demonstrate that this dual-rail storage is a suitable memory for high fidelity frequency qubits. The two signals are stored simultaneously in the Zeeman-split Raman absorption lines of a cold atom ensemble using gradient echo memory techniques. Analysis of the split-Zeeman storage shows that the memory can be configured to preserve the relative amplitude and phase of the frequency separated signals. In an experimental demonstration dual-frequency pulses are recalled with 35% efficiency, 82% interference fringe visibility, and 6 degrees phase stability. The fidelity of the frequency-qubit memory is limited by frequency-dependent polarisation rotation and ambient magnetic field fluctuations, our analysis describes how these can be addressed in an alternative configuration.

  7. Anthropomorphic dual-arm space telemanipulation system

    NASA Technical Reports Server (NTRS)

    Jau, Bruno M.

    1990-01-01

    Dexterous dual-arm manipulations are feasible with the system described and illustrated in the paper. The structure is based on an extensible host arm that carries the dual-arm robot which comprises two 7-DOF arms each of which includes a hand with a thumb and three fingers with 4 DOF each. Joint compliance can be stiffened to any level, and the operator uses arm harnesses and gloves to utilize the robotics in an anthropomorphic fashion. The configuration eliminates coordinate-transformation computations, and the system is found to achieve a control-frequency rate of 1000 Hz for its direct man/machine interfaces based on fiber-optic cables. The electronics control for the system utilizes a sensory system consisting of force, position, and compliance sensors. The robotics system is expected to be a user-friendly device that permits assembly, repair, tethering, and other complex mechanical operations.

  8. Dual-Telescope Multi-Channel Thermal-Infrared Radiometer for Outer Planet Fly-By Missions

    NASA Technical Reports Server (NTRS)

    Aslam, Shahid; Amato, Michael; Bowles, Neil; Calcutt, Simon; Hewagama, Tilak; Howard, Joseph; Howett, Carly; Hsieh, Wen-Ting; Hurford, Terry; Hurley, Jane; Jennings, Donald E.; Lakew, Brook; Loeffler, Mark; Nicoletti, Anthony; Nixon, Conor A.; Quilligan, Gerard; West, Garrett

    2016-01-01

    The design of a versatile dual-telescope thermal-infrared radiometer spanning the spectral wavelength range 8-200 microns, in five spectral pass bands, for outer planet fly-by missions is described. The dual- telescope design switches between a narrow-field-of-view and a wide-field-of-view to provide optimal spatial resolution images within a range of spacecraft encounters to the target. The switchable dual-field- of-view system uses an optical configuration based on the axial rotation of a source-select mirror along the optical axis. The optical design, spectral performance, radiometric accuracy, and retrieval estimates of the instrument are discussed. This is followed by an assessment of the surface coverage performance at various spatial resolutions by using the planned NASA Europa Mission 13-F7 fly-by trajectories as a case study.

  9. Tunable Terahertz-wave generation from DAST crystal pumped by a monolithic dual-wavelength fiber laser.

    PubMed

    Tang, Ming; Minamide, Hiroaki; Wang, Yuye; Notake, Takashi; Ohno, Seigo; Ito, Hiromasa

    2011-01-17

    For developing a continuous-wave (CW) tunable Terahertz-wave (THz-wave) source using difference-frequency generation (DFG) in highly nonlinear optical crystals, we proposed and demonstrated a dual-wavelength fiber ring laser system operating around 1060 nm based on wideband chirped fiber Bragg gratings (CFBGs) and semiconductor optical amplifier (SOA). Thermo-induced phase shift along the CFBG produces a very sharp transmission spike therefore two lasing wavelengths with single longitudinal mode operation are oscillating simultaneously within the fiber ring cavity. Due to the inhomogeneous gain broadening property of SOA, the wavelength spacing of our dual-wavelength fiber laser can be continuously adjusted from 0.3 to 9.5 nm. By using this single emitter dual-wavelength fiber laser to pump an organic nonlinear DAST crystal, type-0 collinear phase matching of DFG process can be fulfilled and monochromatic THz wave ranging from 0.5 to 2 THz has been successfully generated.

  10. Simultaneous dual-wavelength eye-safe KTP OPO intracavity pumped by a Nd:GYSGG laser

    NASA Astrophysics Data System (ADS)

    Wang, Maorong; Zhong, Kai; Mei, Jialin; Guo, Shibei; Xu, Degang; Yao, Jianquan

    2016-02-01

    A simultaneous dual-wavelength intracavity pumped non-critical eye-safe optical parametric oscillator (OPO) is realized using a Nd:GYSGG laser crystal and a KTP nonlinear crystal. A folded cavity is used for thermal stability and mode matching, which greatly improves the output characteristics versus a linear cavity. The maximum output power of the 1562.1 nm/1567.4 nm dual-wavelength eye-safe laser is 750 mW at 10 kHz, corresponding to the optical-to-optical conversion efficiency, single-pulse-energy and peak power of 5.8%, 75 μJ and 22.7 kW. Such a dual-wavelength OPO provides a good laser source for remote sensing for CO and CO2 gases or difference frequency generation for terahertz wave at the important 0.65 THz band.

  11. Dual-telescope multi-channel thermal-infrared radiometer for outer planet fly-by missions

    NASA Astrophysics Data System (ADS)

    Aslam, Shahid; Amato, Michael; Bowles, Neil; Calcutt, Simon; Hewagama, Tilak; Howard, Joseph; Howett, Carly; Hsieh, Wen-Ting; Hurford, Terry; Hurley, Jane; Irwin, Patrick; Jennings, Donald E.; Kessler, Ernst; Lakew, Brook; Loeffler, Mark; Mellon, Michael; Nicoletti, Anthony; Nixon, Conor A.; Putzig, Nathaniel; Quilligan, Gerard; Rathbun, Julie; Segura, Marcia; Spencer, John; Spitale, Joseph; West, Garrett

    2016-11-01

    The design of a versatile dual-telescope thermal-infrared radiometer spanning the spectral wavelength range 8-200 μm, in five spectral pass bands, for outer planet fly-by missions is described. The dual-telescope design switches between a narrow-field-of-view and a wide-field-of-view to provide optimal spatial resolution images within a range of spacecraft encounters to the target. The switchable dual-field-of-view system uses an optical configuration based on the axial rotation of a source-select mirror along the optical axis. The optical design, spectral performance, radiometric accuracy, and retrieval estimates of the instrument are discussed. This is followed by an assessment of the surface coverage performance at various spatial resolutions by using the planned NASA Europa Mission 13-F7 fly-by trajectories as a case study.

  12. Monte Carlo modeling of the dual-mode regime in quantum-well and quantum-dot semiconductor lasers.

    PubMed

    Chusseau, Laurent; Philippe, Fabrice; Disanto, Filippo

    2014-03-10

    Monte Carlo markovian models of a dual-mode semiconductor laser with quantum well (QW) or quantum dot (QD) active regions are proposed. Accounting for carriers and photons as particles that may exchange energy in the course of time allows an ab initio description of laser dynamics such as the mode competition and intrinsic laser noise. We used these models to evaluate the stability of the dual-mode regime when laser characteristics are varied: mode gains and losses, non-radiative recombination rates, intraband relaxation time, capture time in QD, transfer of excitation between QD via the wetting layer... As a major result, a possible steady-state dual-mode regime is predicted for specially designed QD semiconductor lasers thereby acting as a CW microwave or terahertz-beating source whereas it does not occur for QW lasers.

  13. Dual-frequency laser Doppler velocimeter for speckle noise reduction and coherence enhancement.

    PubMed

    Cheng, Chih-Hao; Lee, Chia-Wei; Lin, Tzu-Wei; Lin, Fan-Yi

    2012-08-27

    We study the characteristics of a dual-frequency laser Doppler velocimeter (DF-LDV) based on an optically injected semiconductor laser. The laser operated in a period-one (P1) dynamical state with two optical frequencies separated by 11.25 GHz is used as the dual-frequency light source. With a microwave beat signal carried by the light, the DF-LDV possesses both the advantages of good directionality, high intensity, and high spatial resolution from the light and low speckle noise and good coherence from the microwave, respectively. By phase-locking the two frequency components with a microwave signal, the coherence of the dual-frequency light source can be further improved and the detection range can be much extended. In this paper, velocity resolutions of the DF-LDV with different amounts of speckle noise and at different detection ranges are experimentally measured and analyzed. Compared with the conventional single-frequency LDV (SF-LDV), the velocity resolution of the DF-LDV is improved by 8 × 10(3) times from 2.5 m/s to 0.31 mm/s for a target with a longitudinal velocity vz = 4 cm/s, a transverse velocity vt = 5 m/s, and at a detection range of 108 m.

  14. Force Spectroscopy with Dual-Trap Optical Tweezers: Molecular Stiffness Measurements and Coupled Fluctuations Analysis

    PubMed Central

    Ribezzi-Crivellari, M.; Ritort, F.

    2012-01-01

    Dual-trap optical tweezers are often used in high-resolution measurements in single-molecule biophysics. Such measurements can be hindered by the presence of extraneous noise sources, the most prominent of which is the coupling of fluctuations along different spatial directions, which may affect any optical tweezers setup. In this article, we analyze, both from the theoretical and the experimental points of view, the most common source for these couplings in dual-trap optical-tweezers setups: the misalignment of traps and tether. We give criteria to distinguish different kinds of misalignment, to estimate their quantitative relevance and to include them in the data analysis. The experimental data is obtained in a, to our knowledge, novel dual-trap optical-tweezers setup that directly measures forces. In the case in which misalignment is negligible, we provide a method to measure the stiffness of traps and tether based on variance analysis. This method can be seen as a calibration technique valid beyond the linear trap region. Our analysis is then employed to measure the persistence length of dsDNA tethers of three different lengths spanning two orders of magnitude. The effective persistence length of such tethers is shown to decrease with the contour length, in accordance with previous studies. PMID:23199920

  15. Dual-Antenna Microwave Reception Without Switching

    NASA Technical Reports Server (NTRS)

    Hartop, Robert W.

    1994-01-01

    Receiver remains connected to both antennas, transmitter switched to connect it to one or other. Combination of hybrid junction, circulators, and filter provides simultaneous reception paths from both antennas without significantly altering radiation patterns of antennas. Communication system considered for use in spacecraft and in which mechanical switch permitted on downlink but not on uplink. Applicable to terrestrial microwave communication stations subject to dual-antenna requirements.

  16. Fabrication of dual porosity electrode structure

    DOEpatents

    Smith, J.L.; Kucera, E.H.

    1991-02-12

    A substantially entirely fibrous ceramic is described which may have dual porosity of both micro and macro pores. Total porosity may be 60-75% by volume. A method of spraying a slurry perpendicularly to an ambient stream of air is disclosed along with a method of removing binders without altering the fiber morphology. Adding fine ceramic particulates to the green ceramic fibers enhances the sintering characteristics of the fibers. 3 figures.

  17. On dumb holes and their gravity duals

    NASA Astrophysics Data System (ADS)

    Das, Sumit R.; Ghosh, Archisman; Oh, Jae-Hyuk; Shapere, Alfred D.

    2011-04-01

    Inhomogeneous fluid flows which become supersonic are known to produce acoustic analogs of ergoregions and horizons. This leads to Hawking-like radiation of phonons with a temperature essentially given by the gradient of the velocity at the horizon. We find such acoustic dumb holes in charged conformal fluids and use the fluid-gravity correspondence to construct dual gravity solutions. A class of quasinormal modes around these gravitational backgrounds perceive a horizon. Upon quantization, this implies a thermal spectrum for these modes.

  18. Broadband Venetian Blind polarizer with dual vanes

    NASA Technical Reports Server (NTRS)

    Conroy, Bruce L.; Hoppe, Daniel J.; Imbriale, William A.

    1993-01-01

    During development of a Venetian Blind polarizer, high reflections and substantial pattern deformation were noted. Analysis showed that when the polarizer was illuminated slightly off axis, a degenerate mode was excited. This mode is resonant at the design center frequency, and was the cause of the problems. A design developed using dual vanes has been shown to be free of the problem. It also has greater bandwidth.

  19. Dual-modal whole eye photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Wu, Ning; Ren, Qiushi; Li, Changhui

    2014-09-01

    We developed a prototype dual-modal ocular imaging system integrating optical-resolution photoacoustic microscopy and high-frequency ultrasound imaging modalities. This system can perform high-resolution ocular imaging from the anterior region down to the fundus area. The novel system successfully imaged the murine eyes in vivo, including iris, lens, retina, and retinal pigment epithelium. Our results demonstrated that this system has a great potential in the diagnosis of ophthalmic diseases.

  20. A Survey of Dual-Use Issues,

    DTIC Science & Technology

    1996-03-01

    Use Programs V-17 E. Summary V-l 8 References y_2i VI. FOREIGN EXAMPLES OF DUAL-USE VI-1 A. Japanese Aviation VI-1 1- FS- X VI-2 2...cities. The klystron technology that proved key in the advancement of radar research was a spin-on of that research, as were microwaves and X -ray...Technology T -*L u Transfer Lithography ^ ^ t. x -. Total Quality Contamination-Free ^ J Manufacturing Design Manufacturing Systems