Light-cone distribution amplitudes of {xi} and their applications

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

Liu Yonglu; Huang Mingqiu

We present the light-cone distribution amplitudes of the {xi} baryons up to twist six on the basis of QCD conformal partial wave expansion to the leading order conformal spin accuracy. The nonperturbative parameters relevant to the DAs are determined in the framework of the QCD sum rule. The light-cone QCD sum rule approach is used to investigate both the electromagnetic form factors of {xi} and the exclusive semileptonic decay of {xi}{sub c} as applications. Our estimations on the magnetic moments are {mu}{sub {xi}{sup 0}}=-(1.92{+-}0.34){mu}{sub N} and {mu}{sub {xi}{sup -}}=-(1.19{+-}0.03){mu}{sub N}. The decay width of the process {xi}{sub c}{yields}{xi}e{sup +}{nu}{sub e}more » is evaluated to be {gamma}=8.73x10{sup -14} GeV, which is in accordance with the experimental measurements and other theoretical approaches.« less

Production and Decay of {xi}{sub c}{sup 0} at BABAR

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

Aubert, B.; Barate, R.; Boutigny, D.

Using 116.1 fb{sup -1} of data collected by the BABAR detector, we present an analysis of {xi}{sub c}{sup 0} production in B decays and from the cc continuum, with the {xi}{sub c}{sup 0} decaying into {omega}{sup -}K{sup +} and {xi}{sup -}{pi}{sup +} final states. We measure the ratio of branching fractions B({xi}{sub c}{sup 0}{yields}{omega}{sup -}K{sup +})/B({xi}{sub c}{sup 0}{yields}{xi}{sup -}{pi}{sup +}) to be 0.294{+-}0.018{+-}0.016, where the first uncertainty is statistical and the second is systematic. The {xi}{sub c}{sup 0} momentum spectrum is measured on and 40 MeV below the {upsilon}(4S) resonance. From these spectra the branching fraction product B(B{yields}{xi}{sub c}{sup 0}X)xB({xi}{submore » c}{sup 0}{yields}{xi}{sup -}{pi}{sup +}) is measured to be (2.11{+-}0.19{+-}0.25)x10{sup -4}, and the cross-section product {sigma}(e{sup +}e{sup -}{yields}{xi}{sub c}{sup 0}X)xB({xi}{sub c}{sup 0}{yields}{xi}{sup -}{pi}{sup +}) from the continuum is measured to be (388{+-}39{+-}41) fb at a center-of-mass energy of 10.58 GeV.« less

Studies of neutron-rich nuclei far from stability at TRISTAN

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

Gill, R.L.

The ISOL facility, TRISTAN, is a user facility located at Brookhaven National Laboratory's High Flux Beam Reactor. Short-lived, neutron-rich nuclei, far from stability, are produced by thermal neutron fission of /sup 235/U. An extensive array of experimental end stations are available for nuclear structure studies. These studies are augmented by a variety of long-lived ion sources suitable for use at a reactor facility. Some recent results at TRISTAN are presented as examples of using an ISOL facility to study series of nuclei, whereby an effective means of conducting nuclear structure investigations is available.

STABILITY OF THE NEUTRON DOSE DETERMINATION ALGORITHM FOR PERSONAL NEUTRON DOSEMETERS AT DIFFERENT RADON GAS EXPOSURES.

PubMed

Mayer, Sabine; Boschung, Markus; Butterweck, Gernot; Assenmacher, Frank; Hohmann, Eike

2016-09-01

Since 2008 the Paul Scherrer Institute (PSI) has been using a microscope-based automatic scanning system for assessing personal neutron doses with a dosemeter based on PADC. This scanning system, known as TASLImage, includes a comprehensive characterisation of tracks. The distributions of several specific track characteristics such as size, shape and optical density are compared with a reference set to discriminate tracks of alpha particles and non-track background. Due to the dosemeter design at PSI, it is anticipated that radon should not significantly contribute to the creation of additional tracks in the PADC detector. The present study tests the stability of the neutron dose determination algorithm of the personal neutron dosemeter system in operation at PSI at different radon gas exposures. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Stability and stability degree of a cracked flexible rotor supported on journal bearings

NASA Technical Reports Server (NTRS)

Meng, Guang; Gasch, Robert

1994-01-01

This paper investigates the stability and the stability degree of a flexible cracked rotor supported on different kinds of journal bearings. It is found that no matter what kind of bearings is used, the unstable zones caused by rotor crack locate always within the speed ratio (2/N) (1 - Delta K(sub xi)/4) is less than Omega is less than 2/N when gravity parameter W(sub R) is greater than 1.0, and locate always within the speed ratio (2 Omega(sub alpha)/N) (1 - Delta K(sub xi)/4) is less than Omega is less than 2 Omega(sub alpha)/N when W(sub R) is less than 0.1, where Delta K(sub xi) is the crack stiffness ratio, N = 1, 2, 3, 4, 5, ..., and Omega(sub alpha) = ((1 + 2 alpha)/2 alpha)(exp 1/2). When 0.1 is less than W(sub R) is less than 1.0, there is a region where no unstable zones caused by rotor crack exist. Outside the crack ridge zones, the rotor crack has almost no influence on system's stability and stability degree; while within the crack ridge zones, the stability and stability degree depend both on the crack and system's parameters. In some cases, the system may still be stable even when the crack is very large. For small gravity parameter (W(sub R) is less than 0.1), the mass ratio alpha has large influence on the position of unstable region, but its influence on the stability degree is small. The influence of fixed Sommerfeld number S(sub 0) on the crack stability degree is small although S(sub 0) has large influence on the stability degree of uncracked rotor.

Xi-cam: Flexible High Throughput Data Processing for GISAXS

NASA Astrophysics Data System (ADS)

Pandolfi, Ronald; Kumar, Dinesh; Venkatakrishnan, Singanallur; Sarje, Abinav; Krishnan, Hari; Pellouchoud, Lenson; Ren, Fang; Fournier, Amanda; Jiang, Zhang; Tassone, Christopher; Mehta, Apurva; Sethian, James; Hexemer, Alexander

With increasing capabilities and data demand for GISAXS beamlines, supporting software is under development to handle larger data rates, volumes, and processing needs. We aim to provide a flexible and extensible approach to GISAXS data treatment as a solution to these rising needs. Xi-cam is the CAMERA platform for data management, analysis, and visualization. The core of Xi-cam is an extensible plugin-based GUI platform which provides users an interactive interface to processing algorithms. Plugins are available for SAXS/GISAXS data and data series visualization, as well as forward modeling and simulation through HipGISAXS. With Xi-cam's advanced mode, data processing steps are designed as a graph-based workflow, which can be executed locally or remotely. Remote execution utilizes HPC or de-localized resources, allowing for effective reduction of high-throughput data. Xi-cam is open-source and cross-platform. The processing algorithms in Xi-cam include parallel cpu and gpu processing optimizations, also taking advantage of external processing packages such as pyFAI. Xi-cam is available for download online.

Cristobalite X-I: A bridge between low and high density silica polymorphs

NASA Astrophysics Data System (ADS)

Shelton, H.; Tiange, B.; Zurek, E.; Smith, J.; Dera, P.

2017-12-01

SiO2 is one of the most common compounds found on Earth. Despite its chemical simplicity, and because of its crystal chemical characteristics, SiO2 exhibits a complex phase diagram. SiO2 has a wide variety of thermodynamically stable crystalline phases, as well as numerous metastable crystalline and amorphous polymorphs. Many of the phase transition sequences that produce metastable phases of SiO2 are strongly path-dependent, where the rate of change controls the transition just as much as the final conditions. The elusive metastable polymorphs of SiO2 may provide a better understanding of the factors controlling its densification. On compression of α-cristobalite (the high temperature tetrahedral phase of SiO2) to pressures above 12 GPa, a new polymorph known as cristobalite X-I forms. Existence of cristobalite X-I has been known for several decades, however, consensus regarding the exact atomic arrangement has not yet been reached. The X-I phase constitutes an important step in the silica densification process, separating low-density tetrahedral framework structures from high-density octahedral polymorphs. It is unique in being the only non-quenchable high-density SiO2 phase, which reverts back to the tetrahedral low-density form on decompression at ambient temperature. Our new single crystal synchrotron X-ray diffraction experiments, with quasihydrostatic neon as the pressure medium, revealed the structure of this enigmatic phase to consist of octahedral silicate chains with 4-60°-2 zigzag chain geometry. This geometry has not been considered before, but is closely related to post-quartz, stishovite and seifertite. Density functional theory calculations support this observation, confirming the dynamic stability of the X-I arrangement and reasonably reproducing the pressure at which the transformation takes place. The enthalpy of cristobalite X-I is higher than stishovite and seifertite, but it is favored as a high-pressure successor of cristobalite due to a

Optimization of the photoelectric properties and photo-stability of CH3NH3PbBrXI3-X films for efficient planar perovskite solar cells

NASA Astrophysics Data System (ADS)

Jiang, Zhaoyi; Zhang, Weijia; Ma, Denghao; Liu, Haixu; Yu, Wei; Fan, Zhiqiang; Zhang, Yulong; Lu, Chaoqun; Li, Yun

2018-01-01

In this paper, the CH3NH3PbBrXI3-X films were prepared by introducing CH3NH3Br into CH3NH3I precursor solution, after which the microstructure and photoelectric properties of the films were thoroughly investigated. Due to Br incorporation in the perovskite films, the band gap increased and the light absorption was slightly reduced while the charge carrier lifetime was prolonged due to the enhanced crystallinity. For the films with higher bromine content, the red shift of the photoluminescence peaks indicated that the phase segregation appeared in the films under illumination, which led to the formation of the iodine-rich domains in this process and the reduced carrier lifetime. On the contrary, for films with lower bromine content, the red shift of the photoluminescence peaks was negligible, which revealed that instability of the perovskite films under illumination can be suppressed by adjusting the bromine content of the films. Consequently, by moderate Br incorporation (CH3NH3Br/CH3NH3I mole ratio = 3:7), the CH3NH3PbBrXI3-X films with optimal photoelectric properties and photo-stability were achieved, and the stable photoelectric conversion efficiency of corresponding device under illumination can reach 13.8%.

Xi-CAM v1.2.3

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

PANDOLFI, RONALD; KUMAR, DINESH; VENKATAKRISHNAN, SINGANALLUR

Xi-CAM aims to provide a community driven platform for multimodal analysis in synchrotron science. The platform core provides a robust plugin infrastructure for extensibility, allowing continuing development to simply add further functionality. Current modules include tools for characterization with (GI)SAXS, Tomography, and XAS. This will continue to serve as a development base as algorithms for multimodal analysis develop. Seamless remote data access, visualization and analysis are key elements of Xi-CAM, and will become critical to synchrotron data infrastructure as expectations for future data volume and acquisition rates rise with continuously increasing throughputs. The highly interactive design elements of Xi-cam willmore » similarly support a generation of users which depend on immediate data quality feedback during high-throughput or burst acquisition modes.« less

Stability Measurements for Alignment of the NIF Neutron Imaging System Pinhole Array

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

Fittinghoff, D N; Bower, D E; Drury, O B

2011-03-29

The alignment system for the National Ignition Facility's neutron imaging system has been commissioned and measurements of the relative stability of the 90-315 DIM, the front and the back of the neutron imaging pinhole array and an exploding pusher target have been made using the 90-135 and the 90-258 opposite port alignment systems. Additionally, a laser beam shot from the neutron-imaging Annex and reflected from a mirror at the back of the pinhole array was used to monitor the pointing of the pinhole. Over a twelve hour period, the relative stability of these parts was found to be within {approx}more » {+-}18 {micro}m rms even when using manual methods for tracking the position of the objects. For highly visible features, use of basic particle tracking techniques found that the front of the pinhole array was stable relative to the 90-135 opposite port alignment camera to within {+-}3.4 {micro}m rms. Reregistration, however, of the opposite port alignment systems themselves using the target alignment sensor was found to change the expected position of target chamber center by up to 194 {micro}m.« less

Direct Observation of the Strange b Baryon {xi}{sub b}{sup -}

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

Abazov, V. M.; Alexeev, G. D.; Kalinin, A. M.

We report the first direct observation of the strange b baryon {xi}{sub b}{sup -}({xi}{sub b}{sup +}). We reconstruct the decay {xi}{sub b}{sup -}{yields}J/{psi}{xi}{sup -}, with J/{psi}{yields}{mu}{sup +}{mu}{sup -}, and {xi}{sup -}{yields}{lambda}{pi}{sup -}{yields}p{pi}{sup -}{pi}{sup -} in pp collisions at {radical}(s)=1.96 TeV. Using 1.3 fb{sup -1} of data collected by the D0 detector, we observe 15.2{+-}4.4(stat){sub -0.4}{sup +1.9}(syst) {xi}{sub b}{sup -} candidates at a mass of 5.774{+-}0.011(stat){+-}0.015(syst) GeV. The significance of the observed signal is 5.5{sigma}, equivalent to a probability of 3.3x10{sup -8} of it arising from a background fluctuation. Normalizing to the decay {lambda}{sub b}{yields}J/{psi}{lambda}, we measure the relative rate ({sigma}({xi}{submore » b}{sup -})xB({xi}{sub b}{sup -}{yields}J/{psi}{xi}{sup -})/{sigma}({lambda}{sub b})xB({lambda}{sub b}{yields}J/{psi}{lambda}))=0.28{+-}0.09(stat){sub -0.08}{sup +0.09}(syst)« less

Xi-cam: a versatile interface for data visualization and analysis

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

Pandolfi, Ronald J.; Allan, Daniel B.; Arenholz, Elke

Xi-cam is an extensible platform for data management, analysis and visualization.Xi-camaims to provide a flexible and extensible approach to synchrotron data treatment as a solution to rising demands for high-volume/high-throughput processing pipelines. The core ofXi-camis an extensible plugin-based graphical user interface platform which provides users with an interactive interface to processing algorithms. Plugins are available for SAXS/WAXS/GISAXS/GIWAXS, tomography and NEXAFS data. WithXi-cam's `advanced' mode, data processing steps are designed as a graph-based workflow, which can be executed live, locally or remotely. Remote execution utilizes high-performance computing or de-localized resources, allowing for the effective reduction of high-throughput data.Xi-cam's plugin-based architecture targetsmore » cross-facility and cross-technique collaborative development, in support of multi-modal analysis.Xi-camis open-source and cross-platform, and available for download on GitHub.« less

Xi-cam: a versatile interface for data visualization and analysis

DOE PAGES

Pandolfi, Ronald J.; Allan, Daniel B.; Arenholz, Elke; ...

2018-05-31

Xi-cam is an extensible platform for data management, analysis and visualization.Xi-camaims to provide a flexible and extensible approach to synchrotron data treatment as a solution to rising demands for high-volume/high-throughput processing pipelines. The core ofXi-camis an extensible plugin-based graphical user interface platform which provides users with an interactive interface to processing algorithms. Plugins are available for SAXS/WAXS/GISAXS/GIWAXS, tomography and NEXAFS data. WithXi-cam's `advanced' mode, data processing steps are designed as a graph-based workflow, which can be executed live, locally or remotely. Remote execution utilizes high-performance computing or de-localized resources, allowing for the effective reduction of high-throughput data.Xi-cam's plugin-based architecture targetsmore » cross-facility and cross-technique collaborative development, in support of multi-modal analysis.Xi-camis open-source and cross-platform, and available for download on GitHub.« less

Modified TOV in gravity’s rainbow: properties of neutron stars and dynamical stability conditions

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

Hendi, S.H.; Research Institute for Astronomy and Astrophysics of Maragha; Bordbar, G.H.

In this paper, we consider a spherical symmetric metric to extract the hydrostatic equilibrium equation of stars in (3+1)-dimensional gravity’s rainbow in the presence of cosmological constant. Then, we generalize the hydrostatic equilibrium equation to d-dimensions and obtain the hydrostatic equilibrium equation for this gravity. Also, we obtain the maximum mass of neutron star using the modern equations of state of neutron star matter derived from the microscopic calculations. It is notable that, in this paper, we consider the effects of rainbow functions on the diagrams related to the mass-central mass density (M-ρ{sub c}) relation and also the mass-radius (M-R)more » relation of neutron star. We also study the effects of rainbow functions on the other properties of neutron star such as the Schwarzschild radius, average density, strength of gravity and gravitational redshift. Then, we apply the cosmological constant to this theory to obtain the diagrams of M-ρ{sub c} (or M-R) and other properties of these stars. Next, we investigate the dynamical stability condition for these stars in gravity’s rainbow and show that these stars have dynamical stability. We also obtain a relation between mass of neutron stars and Planck mass. In addition, we compare obtained results of this theory with the observational data.« less

Search for the lepton-number-violating decay Xi(-)-->pmu(-)mu(-).

PubMed

Rajaram, D; Burnstein, R A; Chakravorty, A; Chan, A; Chen, Y C; Choong, W S; Clark, K; Dukes, E C; Durandet, C; Felix, J; Gidal, G; Gu, P; Gustafson, H R; Ho, C; Holmstrom, T; Huang, M; James, C; Jenkins, C M; Kaplan, D M; Lederman, L M; Leros, N; Longo, M J; Lopez, F; Lu, L C; Luebke, W; Luk, K B; Nelson, K S; Park, H K; Perroud, J-P; Rubin, H A; Teng, P K; Volk, J; White, C G; White, S L; Zyla, P

2005-05-13

A sensitive search for the lepton-number-violating decay Xi(-)-->pmu(-)mu(-) has been performed using a sample of approximately 10(9) Xi(-) hyperons produced in 800 GeV/c p-Cu collisions. We obtain B(Xi(-)-->pmu(-)mu(-))<4.0x10(-8) at 90% confidence, improving on the best previous limit by 4 orders of magnitude.

Study of excited charm-strange baryons with evidence for new baryons {xi}{sub c}(3055){sup +} and {xi}{sub c}(3123){sup +}

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

Aubert, B.; Bona, M.; Boutigny, D.

We present a study of excited charm-strange baryon states produced in e{sup +}e{sup -} annihilations at or near a center-of-mass energy of 10.58 GeV, in a data sample with an integrated luminosity of 384 fb{sup -1} recorded with the BABAR detector at the PEP-II e{sup +}e{sup -} storage rings at the Stanford Linear Accelerator Center. We study strong decays of charm-strange baryons to {lambda}{sub c}{sup +}K{sub S}{sup 0}, {lambda}{sub c}{sup +}K{sup -}, {lambda}{sub c}{sup +}K{sup -}{pi}{sup +}, {lambda}{sub c}{sup +}K{sub S}{sup 0}{pi}{sup -}, {lambda}{sub c}{sup +}K{sub S}{sup 0}{pi}{sup -}{pi}{sup +}, and {lambda}{sub c}{sup +}K{sup -}{pi}{sup +}{pi}{sup -}. This study confirmsmore » the existence of the states {xi}{sub c}(2980){sup +}, {xi}{sub c}(3077){sup +}, and {xi}{sub c}(3077){sup 0}, with a more accurate determination of the {xi}{sub c}(2980){sup +} mass and width. We also present evidence for two new states, {xi}{sub c}(3055){sup +} and {xi}{sub c}(3123){sup +}, decaying through the intermediate-resonant modes {sigma}{sub c}(2455){sup ++}K{sup -} and {sigma}{sub c}(2520){sup ++}K{sup -}, respectively. For each of these baryons, we measure the yield in each final state, determine the statistical significance, and calculate the product of the production cross section and branching fractions. We also measure the masses and widths of these excited charm-strange baryons.« less

Observation of B{sup +}{yields}{xi}{sub c}{sup 0}{lambda}{sub c}{sup +} and evidence for B{sup 0}{yields}{xi}{sub c}{sup -}{lambda}{sub c}{sup +}

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

Chistov, R.; Aushev, T.; Balagura, V.

We report the first observation of the decay B{sup +}{yields}{xi}{sub c}{sup 0}{lambda}{sub c}{sup +} with a significance of 8.7{sigma} and evidence for the decay B{sup 0}{yields}{xi}{sub c}{sup -}{lambda}{sub c}{sup +} with a significance of 3.8{sigma}. The product B(B{sup +}{yields}{xi}{sub c}{sup 0}{lambda}{sub c}{sup +})xB({xi}{sub c}{sup 0}{yields}{xi}{sup +}{pi}{sup -}) is measured to be (4.8{sub -0.9}{sup +1.0}{+-}1.1{+-}1.2)x10{sup -5}, and B(B{sup 0}{yields}{xi}{sub c}{sup -}{lambda}{sub c}{sup +})xB({xi}{sub c}{sup -}{yields}{xi}{sup +}{pi}{sup -}{pi}{sup -}) is measured to be (9.3{sub -2.8}{sup +3.7}{+-}1.9{+-}2.4)x10{sup -5}. The errors are statistical, systematic and the error of the {lambda}{sub c}{sup +}{yields}pK{sup -}{pi}{sup +} branching fraction, respectively. The decay B{sup +}{yields}{xi}{sub c}{sup 0}{lambda}{sub c}{supmore » +} is the first example of a two-body exclusive B{sup +} decay into two charmed baryons. The data used for this analysis was accumulated at the {upsilon}(4S) resonance, using the Belle detector at the e{sup +}e{sup -} asymmetric-energy collider KEKB. The integrated luminosity of the data sample is equal to 357 fb{sup -1}, corresponding to 386x10{sup 6} BB pairs.« less

MuPeXI: prediction of neo-epitopes from tumor sequencing data.

PubMed

Bjerregaard, Anne-Mette; Nielsen, Morten; Hadrup, Sine Reker; Szallasi, Zoltan; Eklund, Aron Charles

2017-09-01

Personalization of immunotherapies such as cancer vaccines and adoptive T cell therapy depends on identification of patient-specific neo-epitopes that can be specifically targeted. MuPeXI, the mutant peptide extractor and informer, is a program to identify tumor-specific peptides and assess their potential to be neo-epitopes. The program input is a file with somatic mutation calls, a list of HLA types, and optionally a gene expression profile. The output is a table with all tumor-specific peptides derived from nucleotide substitutions, insertions, and deletions, along with comprehensive annotation, including HLA binding and similarity to normal peptides. The peptides are sorted according to a priority score which is intended to roughly predict immunogenicity. We applied MuPeXI to three tumors for which predicted MHC-binding peptides had been screened for T cell reactivity, and found that MuPeXI was able to prioritize immunogenic peptides with an area under the curve of 0.63. Compared to other available tools, MuPeXI provides more information and is easier to use. MuPeXI is available as stand-alone software and as a web server at http://www.cbs.dtu.dk/services/MuPeXI .

Gain stabilization control system of the upgraded magnetic proton recoil neutron spectrometer at JET.

PubMed

Sjöstrand, Henrik; Andersson Sundén, E; Conroy, S; Ericsson, G; Gatu Johnson, M; Giacomelli, L; Gorini, G; Hellesen, C; Hjalmarsson, A; Popovichev, S; Ronchi, E; Tardocchi, M; Weiszflog, M

2009-06-01

Burning plasma experiments such as ITER and DEMO require diagnostics capable of withstanding the harsh environment generated by the intense neutron flux and to maintain stable operating conditions for times longer than present day systems. For these reasons, advanced control and monitoring (CM) systems will be necessary for the reliable operation of diagnostics. This paper describes the CM system of the upgraded magnetic proton recoil neutron spectrometer installed at the Joint European Torus focusing in particular on a technique for the stabilization of the gain of the photomultipliers coupled to the neutron detectors. The results presented here show that this technique provides good results over long time scales. The technique is of general interest for all diagnostics that employ scintillators coupled to photomultiplier tubes.

Aristolochic acid-related nephropathy associated with the popular Chinese herb Xi Xin.

PubMed

Yang, Huang-Yu; Lin, J-L; Chen, Kuan-Hsing; Yu, Chun-Chen; Hsu, Po-Yaur; Lin, Chun-Liang

2006-01-01

Chinese herbs nephropathy is known as a subacute interstitial nephritis attributed to aristolochic acid. This work describes the case of a 49-year-old male who displayed subacute renal failure induced by ingestion of herbal powder containing Xi Xin, which includes aristolochic acid. Since Xi Xin is a common ingredient in traditional formulae, care needs to be taken in the future to identify the aristolochic acid concentration of different components of Xi Xin. Xi Xin containing aristolochic acid should be forbidden for use in remedies in order to prevent the harmful effects of aristolochic acid.

Donor motivation in Xi'an, China: comparison with Canadian donors.

PubMed

O'Brien, S F; Shao, Z-J; Osmond, L; Yi, Q-L; Li, C-Y; An, Q-X

2013-04-01

In China, paid donation is prohibited by law. There is little literature assessing donor motivation in China, and comparison with western countries such as Canada is important in understanding the application of Western literature. We compared motivational factors in donors from the city of Xi'an, China, with Canadian donors matched for age, sex and donation status. A total of 218 donors in Xi'an completed an interview about motivation as did 218 Canadian donors matched for age, sex and donation status. Frequencies and percentages of responses to questions were tabulated and compared using the Chi-squared test. Donors in Xi'an and Canada felt a personal responsibility to donate blood (81·2% vs. 78·0%, P = 0·2057), but Xi'an donors were more likely to consider blood donation a social responsibility (81·7% vs. 45·2%, P < 0·0001). Xi'an donors more often believed that society views donation as a normal activity (98·6% vs. 48·4%, P < 0·0001) and that the social atmosphere promotes donation (90·3% vs. 53·5%, P < 0·0001) and saw greater health benefit (52·3% vs. 12·5%, P < 0·0001). Most Xi'an donors believed in balance between their life force (Qi) and blood (86·7% vs. 49·8%, P < 0·0001) but did not believe blood lost from donating would affect this (0·5% vs. 3·8%, P = 0·01). While traditional Chinese beliefs may not be seen as a barrier among people in Xi'an who donate blood, blood donation is seen differently than by Canadian donors. There is a need for more research specific to China to tailor recruitment strategies. © 2012 The Author(s). Vox Sanguinis © 2012 International Society of Blood Transfusion.

xiSPEC: web-based visualization, analysis and sharing of proteomics data.

PubMed

Kolbowski, Lars; Combe, Colin; Rappsilber, Juri

2018-05-08

We present xiSPEC, a standard compliant, next-generation web-based spectrum viewer for visualizing, analyzing and sharing mass spectrometry data. Peptide-spectrum matches from standard proteomics and cross-linking experiments are supported. xiSPEC is to date the only browser-based tool supporting the standardized file formats mzML and mzIdentML defined by the proteomics standards initiative. Users can either upload data directly or select files from the PRIDE data repository as input. xiSPEC allows users to save and share their datasets publicly or password protected for providing access to collaborators or readers and reviewers of manuscripts. The identification table features advanced interaction controls and spectra are presented in three interconnected views: (i) annotated mass spectrum, (ii) peptide sequence fragmentation key and (iii) quality control error plots of matched fragments. Highlighting or selecting data points in any view is represented in all other views. Views are interactive scalable vector graphic elements, which can be exported, e.g. for use in publication. xiSPEC allows for re-annotation of spectra for easy hypothesis testing by modifying input data. xiSPEC is freely accessible at http://spectrumviewer.org and the source code is openly available on https://github.com/Rappsilber-Laboratory/xiSPEC.

Search for Exotic Baryons in 800 GeV pp{yields}p{xi}{sup {+-}}{pi}{sup {+-}}X Reactions

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

Christian, D.C.; Gottschalk, E.E.; Gutierrez, G.

We report the results of a high-statistics, sensitive search for narrow baryon resonances decaying to {xi}{sup -}{pi}{sup -}, {xi}{sup -}{pi}{sup +}, {xi}{sup +}{pi}{sup -}, and {xi}{sup +}{pi}{sup +}. The only resonances observed are the well known {xi}{sup 0}(1530) and {xi}{sup 0}(1530). No evidence is found for the states near 1862 MeV, previously reported by NA49 [Phys. Rev. Lett. 92, 042003 (2003)]. At the 95% confidence level, we find the upper limit for the production of a Gaussian enhancement with {sigma}=7.6 MeV in the {xi}{sup -}{pi}{sup -} effective mass spectrum to be 0.3% of the number of observed {xi}{sup 0}(1530){yields}{xi}{sup -}{pi}{supmore » +}. We find similarly restrictive upper limits for an enhancement at 1862 MeV in the {xi}{sup -}{pi}{sup +}, {xi}{sup +}{pi}{sup -}, and {xi}{sup +}{pi}{sup +} mass spectra.« less

The Da Vinci Xi and robotic radical prostatectomy-an evolution in learning and technique.

PubMed

Goonewardene, S S; Cahill, D

2017-06-01

The da Vinci Xi robot has been introduced as the successor to the Si platform. The promise of the Xi is to open the door to new surgical procedures. For robotic-assisted radical prostatectomy (RARP)/pelvic surgery, the potential is better vision and longer instruments. How has the Xi impacted on operative and pathological parameters as indicators of surgical performance? This is a comparison of an initial series of 42 RARPs with the Xi system in 2015 with a series using the Si system immediately before Xi uptake in the same calendar year, and an Si series by the same surgeon synchronously as the Xi series using operative time, blood loss, and positive margins as surrogates of surgical performance. Subjectively and objectively, there is a learning curve to Xi uptake in longer operative times but no impact on T2 positive margins which are the most reflective single measure of RARP outcomes. Subjectively, the vision of the Xi is inferior to the Si system, and the integrated diathermy system and automated setup are quirky. All require experience to overcome. There is a learning curve to progress from the Si to Xi da Vinci surgical platforms, but this does not negatively impact the outcome.

Inhibition of d-xylose isomerase by polyols: atomic details by joint X-ray/neutron crystallography

PubMed Central

Kovalevsky, Andrey; Hanson, B. Leif; Mason, Sax A.; Forsyth, V. Trevor; Fisher, Zoe; Mustyakimov, Marat; Blakeley, Matthew P.; Keen, David A.; Langan, Paul

2012-01-01

d-Xylose isomerase (XI) converts the aldo-sugars xylose and glucose to their keto analogs xylulose and fructose, but is strongly inhibited by the polyols xylitol and sorbitol, especially at acidic pH. In order to understand the atomic details of polyol binding to the XI active site, a 2.0 Å resolution room-temperature joint X-ray/neutron structure of XI in complex with Ni2+ cofactors and sorbitol inhibitor at pH 5.9 and a room-temperature X-ray structure of XI containing Mg2+ ions and xylitol at the physiological pH of 7.7 were obtained. The protonation of oxygen O5 of the inhibitor, which was found to be deprotonated and negatively charged in previous structures of XI complexed with linear glucose and xylulose, was directly observed. The Ni2+ ions occupying the catalytic metal site (M2) were found at two locations, while Mg2+ in M2 is very mobile and has a high B factor. Under acidic conditions sorbitol gains a water-mediated interaction that connects its O1 hydroxyl to Asp257. This contact is not found in structures at basic pH. The new interaction that is formed may improve the binding of the inhibitor, providing an explanation for the increased affinity of the polyols for XI at low pH. PMID:22948921

TlBr and TlBr xI 1-x crystals for γ-ray detectors

NASA Astrophysics Data System (ADS)

Churilov, Alexei V.; Ciampi, Guido; Kim, Hadong; Higgins, William M.; Cirignano, Leonard J.; Olschner, Fred; Biteman, Viktor; Minchello, Mark; Shah, Kanai S.

2010-04-01

TlBr and TlBr xI 1-x are wide bandgap semiconductor materials being investigated for applications in γ-ray spectroscopy. They have a good combination of density and atomic numbers, promising to make them very efficient detectors. Their low melting points and simple cubic and orthorhombic crystal structures are favorable for bulk crystal growth. However, these semiconductors need to be extremely pure to become useful as radiation detectors. Impurities can lead to charge trapping and scattering, reducing the charge transit lengths and limiting the detector thickness to <1 mm. Additional purification steps were implemented to improve the purity and mobility-lifetime product ( μτ) of electrons. Detector-grade TlBr with the electron μτ product of up to 6×10 -3 cm 2/V has been produced, which allowed operation of detectors up to 15 mm thickness. The ternary TlBr xI 1-x was investigated at different compositions to vary the bandgap and explore the effect of added TlI on the long term stability of detectors. The material analysis and detector characterization results are included.

Da Vinci Xi Robot–Assisted Penetrating Keratoplasty

PubMed Central

Chammas, Jimmy; Sauer, Arnaud; Pizzuto, Joëlle; Pouthier, Fabienne; Gaucher, David; Marescaux, Jacques; Mutter, Didier; Bourcier, Tristan

2017-01-01

Purpose This study aims (1) to investigate the feasibility of robot-assisted penetrating keratoplasty (PK) using the new Da Vinci Xi Surgical System and (2) to report what we believe to be the first use of this system in experimental eye surgery. Methods Robot-assisted PK procedures were performed on human corneal transplants using the Da Vinci Xi Surgical System. After an 8-mm corneal trephination, four interrupted sutures and one 10.0 monofilament running suture were made. For each procedure, duration and successful completion of the surgery as well as any unexpected events were assessed. The depth of the corneal sutures was checked postoperatively using spectral-domain optical coherence tomography (SD-OCT). Results Robot-assisted PK was successfully performed on 12 corneas. The Da Vinci Xi Surgical System provided the necessary dexterity to perform the different steps of surgery. The mean duration of the procedures was 43.4 ± 8.9 minutes (range: 28.5–61.1 minutes). There were no unexpected intraoperative events. SD-OCT confirmed that the sutures were placed at the appropriate depth. Conclusions We confirm the feasibility of robot-assisted PK with the new Da Vinci Surgical System and report the first use of the Xi model in experimental eye surgery. Operative time of robot-assisted PK surgery is now close to that of conventional manual surgery due to both improvement of the optical system and the presence of microsurgical instruments. Translational Relevance Experimentations will allow the advantages of robot-assisted microsurgery to be identified while underlining the improvements and innovations necessary for clinical use. PMID:28660096

Da Vinci Xi Robot-Assisted Penetrating Keratoplasty.

PubMed

Chammas, Jimmy; Sauer, Arnaud; Pizzuto, Joëlle; Pouthier, Fabienne; Gaucher, David; Marescaux, Jacques; Mutter, Didier; Bourcier, Tristan

2017-06-01

This study aims (1) to investigate the feasibility of robot-assisted penetrating keratoplasty (PK) using the new Da Vinci Xi Surgical System and (2) to report what we believe to be the first use of this system in experimental eye surgery. Robot-assisted PK procedures were performed on human corneal transplants using the Da Vinci Xi Surgical System. After an 8-mm corneal trephination, four interrupted sutures and one 10.0 monofilament running suture were made. For each procedure, duration and successful completion of the surgery as well as any unexpected events were assessed. The depth of the corneal sutures was checked postoperatively using spectral-domain optical coherence tomography (SD-OCT). Robot-assisted PK was successfully performed on 12 corneas. The Da Vinci Xi Surgical System provided the necessary dexterity to perform the different steps of surgery. The mean duration of the procedures was 43.4 ± 8.9 minutes (range: 28.5-61.1 minutes). There were no unexpected intraoperative events. SD-OCT confirmed that the sutures were placed at the appropriate depth. We confirm the feasibility of robot-assisted PK with the new Da Vinci Surgical System and report the first use of the Xi model in experimental eye surgery. Operative time of robot-assisted PK surgery is now close to that of conventional manual surgery due to both improvement of the optical system and the presence of microsurgical instruments. Experimentations will allow the advantages of robot-assisted microsurgery to be identified while underlining the improvements and innovations necessary for clinical use.

Study of the Rare Hyperon Decay $${\\boldmath \\Omega^\\mp \\to \\Xi^\\mp \\: \\pi^+\\pi^-}$$

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

Kamaev, O.; Solomey, N.; Burnstein, R.A.

The authors report a new measurement of the decay {Omega}{sup -} {yields} {Xi}{sup -} {pi}{sup +}{pi}{sup -} with 76 events and a first observation of the decay {bar {Omega}}{sup +} {yields} {bar {Xi}}{sup +} {pi}{sup +}{pi}{sup -} with 24 events, yielding a combined branching ratio (3.74{sub -0.56}{sup +0.67}) x 10{sup -4}. This represents a factor 25 increase in statistics over the best previous measurement. No evidence is seen for CP violation, with {Beta}({Omega}{sup -} {yields} {Xi}{sup -} {pi}{sup +}{pi}{sup -}) = 4.04{sub -0.71}{sup +0.83} x 10{sup -4} and {Beta}({bar {Omega}}{sup +} {yields} {bar {Xi}}{sup +} {pi}{sup +}{pi}{sup -}) = 3.15{submore » -0.89}{sup +1.12} x 10{sup -4}. Contrary to theoretical expectation, they see little evidence for the decays {Omega}{sup -} {yields} {Xi}*{sub 1530}{sup 0} {pi}{sup -} and {bar {Omega}}{sup +} {yields} {bar {Xi}}*{sub 1530}{sup 0} {pi}{sup +} and place a 90% C.L. upper limit on the combined branching ratio {Beta}({Omega}{sup -}({bar {Omega}}{sup +}) {yields} {Xi}*{sub 1530}{sup 0} ({bar {Xi}}*{sub 1530}{sup 0}){pi}{sup {-+}}) < 7.0 x 10{sup -5}.« less

Equilibrium and Stability Properties of Low Aspect Ratio Mirror Systems: from Neutron Source Design to the Parker Spiral

NASA Astrophysics Data System (ADS)

Peterson, Ethan; Anderson, Jay; Clark, Mike; Egedal, Jan; Endrizzi, Douglass; Flanagan, Ken; Harvey, Robert; Lynn, Jacob; Milhone, Jason; Wallace, John; Waleffe, Roger; Mirnov, Vladimir; Forest, Cary

2017-10-01

Equilibrium reconstructions of rotating magnetospheres in the lab are computed using a user-friendly extended Grad-Shafranov solver written in Python and various magnetic and kinetic measurements. The stability of these equilibria are investigated using the NIMROD code with two goals: understand the onset of the classic ``wobble'' in the heliospheric current sheet and demonstrating proof-of-principle for a laboratory source of high- β turbulence. Using the same extended Grad-Shafranov solver, equilibria for an axisymmetric, non-paraxial magnetic mirror are used as a design foundation for a high-field magnetic mirror neutron source. These equilibria are numerically shown to be stable to the m=1 flute instability, with higher modes likely stabilized by FLR effects; this provides stability to gross MHD modes in an axisymmetric configuration. Numerical results of RF heating and neutral beam injection (NBI) from the GENRAY/CQL3D code suite show neutron fluxes promising for medical radioisotope production as well as materials testing. Synergistic effects between NBI and high-harmonic fast wave heating show large increases in neutron yield for a modest increase in RF power. work funded by DOE, NSF, NASA.

Rapid increase of ozone concentrations in Xi'an, China: Anthropogenically or naturally?

NASA Astrophysics Data System (ADS)

Wu, J.; Li, G.; Junji, C.

2017-12-01

The air quality in the Guanzhong basin, China has deteriorated recently caused by growing industries, city expansions, and increasing transportation activity. We report here a substantial increasing trend of ozone (O3) concentrations in Xi'an, the largest city of the basin, and the average observed O3 concentration in the afternoon during summertime has increased by 39% from 2013 to 2016. There are two main possible reasons for the rapid O3 increase. Motor vehicle has been reported to increase by 35% in Xi'an, which enhances the O3 precursors emissions to facilitate the O3 formation. In addition, the surface solar radiation at the meteorological site in Xi'an has been observed to intensify by 30%, which increases the photolysis rates to expedite the O3 production. A persistent high O3 episode from 16 to 22 June 2016 in Xi'an has been simulated using the WRF-CHEM model to evaluate the contribution of the transportation emission and solar radiation enhancement on the O3 trend. The model generally performs reasonably well in simulating the temporal variation and spatial distribution of near-surface O3 and NO2 concentrations against measurements in Xi'an. Sensitivity studies have revealed that the enhancement of transportation emissions and the solar radiation explains about 70% of the O3 trend from 2013 to 2016. Considering that large amounts of biogenic emissions are released over the Qinling Mountains on the south of Xi'an, which can be delivered to Xi'an under favorable meteorological conditions, enhancing O3 formation. Therefore, future studies need to be performed to evaluate impacts of the solar radiation enhancement on the biogenic emissions and further the O3 formation in Xi'an.

Factor XI Antisense Oligonucleotide for Prevention of Venous Thrombosis

PubMed Central

Büller, Harry R.; Bethune, Claudette; Bhanot, Sanjay; Gailani, David; Monia, Brett P.; Raskob, Gary E.; Segers, Annelise; Verhamme, Peter; Weitz, Jeffrey I.

2015-01-01

BACKGROUND Experimental data indicate that reducing factor XI levels attenuates thrombosis without causing bleeding, but the role of factor XI in the prevention of postoperative venous thrombosis in humans is unknown. FXI-ASO (ISIS 416858) is a second-generation antisense oligonucleotide that specifically reduces factor XI levels. We compared the efficacy and safety of FXI-ASO with those of enoxaparin in patients undergoing total knee arthroplasty. METHODS In this open-label, parallel-group study, we randomly assigned 300 patients who were undergoing elective primary unilateral total knee arthroplasty to receive one of two doses of FXI-ASO (200 mg or 300 mg) or 40 mg of enoxaparin once daily. The primary efficacy outcome was the incidence of venous thromboembolism (assessed by mandatory bilateral venography or report of symptomatic events). The principal safety outcome was major or clinically relevant nonmajor bleeding. RESULTS Around the time of surgery, the mean (±SE) factor XI levels were 0.38±0.01 units per milliliter in the 200-mg FXI-ASO group, 0.20±0.01 units per milliliter in the 300-mg FXI-ASO group, and 0.93±0.02 units per milliliter in the enoxaparin group. The primary efficacy outcome occurred in 36 of 134 patients (27%) who received the 200-mg dose of FXI-ASO and in 3 of 71 patients (4%) who received the 300-mg dose of FXI-ASO, as compared with 21 of 69 patients (30%) who received enoxaparin. The 200-mg regimen was noninferior, and the 300-mg regimen was superior, to enoxaparin (P<0.001). Bleeding occurred in 3%, 3%, and 8% of the patients in the three study groups, respectively. CONCLUSIONS This study showed that factor XI contributes to postoperative venous thromboembolism; reducing factor XI levels in patients undergoing elective primary unilateral total knee arthroplasty was an effective method for its prevention and appeared to be safe with respect to the risk of bleeding. (Funded by Isis Pharmaceuticals; FXI-ASO TKA ClinicalTrials.gov number

Decay widths of ground-state and excited {Xi}{sub b} baryons in a nonrelativistic quark model

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

Limphirat, Ayut; Thailand Center of Excellence in Physics; Department of Applied Physics, Faculty of Sciences and Liberal Arts, Rajamangala University of Technology Isan, Nakhon Ratchasima 30000

Decay processes of ground and excited bottom baryons are studied in the {sup 3}P{sub 0} nonrelativistic quark model with all model parameters fixed in the sector of light quarks. Using as an input the recent mass of {Xi}{sub b} and the theoretical masses of {Xi}{sub b}{sup *} and {Xi}{sub b}{sup '}, narrow decay widths are predicted for the ground-state bottom baryons {Xi}{sub b}{sup *} and {Xi}{sub b}{sup '}. The work predicts large decay widths, about 100 MeV for the {rho}-type orbital excitation states of {Xi}{sub b}.

A Comprehensive Strategy to Evaluate Compatible Stability of Chinese Medicine Injection and Infusion Solutions Based on Chemical Analysis and Bioactivity Assay.

PubMed

Li, Jian-Ping; Liu, Yang; Guo, Jian-Ming; Shang, Er-Xin; Zhu, Zhen-Hua; Zhu, Kevin Y; Tang, Yu-Ping; Zhao, Bu-Chang; Tang, Zhi-Shu; Duan, Jin-Ao

2017-01-01

Stability of traditional Chinese medicine injection (TCMI) is an important issue related with its clinical application. TCMI is composed of multi-components, therefore, when evaluating TCMI stability, several marker compounds cannot represent global components or biological activities of TCMI. Till now, when evaluating TCMI stability, method involving the global components or biological activities has not been reported. In this paper, we established a comprehensive strategy composed of three different methods to evaluate the chemical and biological stability of a typical TCMI, Danhong injection (DHI). UHPLC-TQ/MS was used to analyze the stability of marker compounds (SaA, SaB, RA, DSS, PA, CA, and SG) in DHI, UHPLC-QTOF/MS was used to analyze the stability of global components (MW 80-1000 Da) in DHI, and cell based antioxidant capability assay was used to evaluate the bioactivity of DHI. We applied this strategy to assess the compatible stability of DHI and six infusion solutions (GS, NS, GNS, FI, XI, and DGI), which were commonly used in combination with DHI in clinic. GS was the best infusion solution for DHI, and DGI was the worst one based on marker compounds analysis. Based on global components analysis, XI and DGI were the worst infusion solutions for DHI. And based on bioactivity assay, GS was the best infusion solution for DHI, and XI was the worst one. In conclusion, as evaluated by the established comprehensive strategy, GS was the best infusion solution, however, XI and DGI were the worst infusion solutions for DHI. In the compatibility of DHI and XI or DGI, salvianolic acids in DHI would be degraded, resulting in the reduction of original composition and generation of new components, and leading to the changes of biological activities. This is the essence of instability compatibility of DHI and some infusion solutions. Our study provided references for choosing the reasonable infusion solutions for DHI, which could contribute the improvement of safety

Ultrabass Sounds of the Giant Star xi Hya

NASA Astrophysics Data System (ADS)

2002-05-01

First Observations of Solar-type Oscillations in a Star Very Different from the Sun Summary About 30 years ago, astronomers realised that the Sun resonates like a giant musical instrument with well-defined periods (frequencies). It forms a sort of large, spherical organ pipe. The energy that excites these sound waves comes from the turbulent region just below the Sun's visible surface. Observations of the solar sound waves (known as " helioseismology ") have resulted in enormous progress in the exploration of the interior of the Sun, otherwise hidden from view. As is the case on Earth, seismic techniques can be applied and the detailed interpretation of the observed oscillation periods has provided quite accurate information about the structure and motions inside the Sun, our central star. It has now also become possible to apply this technique to some solar-type stars. The first observations concerned the northern star eta Bootis (cf. ESO PR 16/94 ). Last year, extensive and much more accurate observations with the 1.2-m Swiss telescope at the ESO La Silla Observatory proved that Alpha Centauri , a solar "twin", behaves very much like the Sun (cf. ESO PR 15/01 ), and that some of the periods are quite similar to those in the Sun. These new observational data were of a superb quality, and that study marked a true break-through in the new research field of " asteroseismology " (seismology of the stars) for solar-type stars. But what about other types of stars, for instance those that are much larger than the Sun? Based on an extremely intensive observing project with the same telescope, an international group of astronomers [1] has found that the giant star xi Hya ("xi" is the small greek letter [2]; "Hya" is an abbreviation of "Hydrae") behaves like a giant sub-ultra-bass instrument . This star is located in the constellation Hydra (the Water-Monster) at a distance of 130 light-years, it has a radius about 10 times that of the Sun and its luminosity is about 60

Effects of Pressure on Stability of Biomolecules in Solutions Studied by Neutron Scattering

NASA Astrophysics Data System (ADS)

Bellissent-Funel, Marie-Claire-; Appavou, Marie-Sousai; Gibrat, Gabriel

Studies of the pressure dependence on protein structure and dynamics contribute not only to the basic knowledge of biological molecules but have also a considerable relevance in full technology, like in food sterilization and pharmacy. Conformational changes induced by pressure as well as the effects on the protein stability have been mostly studied by optical techniques (optical absorption, fluorescence, phosphorescence), and by NMR. Most optical techniques used so far give information related to the local nature of the used probe (fluorescent or phosphorescent tryptophan). Small angle neutron scattering and quasi-elastic neutron scattering provide essential complementary information to the optical data, giving quantitative data on change of conformation of soluble globular proteins such as bovine pancreatic trypsin inhibitor (BPTI) and on the mobility of protons belonging to the protein surface residues.

Hadronic production of the doubly heavy baryon {Xi}{sub bc} at the LHC

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

Zhang Jiawei; Wu Xinggang; Zhong Tao

We investigate the hadronic production of the doubly heavy baryon {Xi}{sub bc} at the Large Hadron Collider (LHC), where contributions from the four (bc)-diquark states (bc){sub 3,6}[{sup 1}S{sub 0}] and (bc){sub 3,6}[{sup 3}S{sub 1}] have been taken into consideration. Numerical results show that under the condition of p{sub T}>4 GeV and |y|<1.5, sizable {Xi}{sub bc} events about 1.7x10{sup 7} and 3.5x10{sup 9} per year can be produced for the center-of-mass energy {radical}(S)=7 TeV and {radical}(S)=14 TeV, respectively. For experimental usage, the total and the interested differential cross sections are estimated under some typical p{sub T} and y cuts for themore » LHC detectors CMS, ATLAS, and LHCb. The main uncertainties are discussed and a comparative study on the hadronic production of {Xi}{sub cc}, {Xi}{sub bc}, and {Xi}{sub bb} at the LHC are also presented.« less

A Dependence Study of $$\\Xi^{*0}$$ and $$\\bar{\\Xi}^{*0}$$ in 250 GeV/c $$\\pi^-$$. $K^-$ -nucleon Interactions (in Portuguese)

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

Seixas de Rezende, Fabio Antonio; /Rio de Janeiro, CBPF

A direct measurement of the mass number (A) dependence of the production of the hyperon {Xi}*{sup 0} and its opposite {bar {Xi}}*{sup 0} in {pi}{sup -}, K{sup -} beam-nucleon interactions at 250 GeV/c is reported. The data derive from the experiment E769 at Fermilab. The results were obtained for different targets: Be, Al, Cu and W. It was observed the data are found to be well described by the parametrization {sigma}{sub A} = {sigma}{sub 0}A{sup {alpha}}, {alpha} being calculated for different beams. The results obtained are compared with those results of E769 experiment. The results shown here are preliminary.

'Tertiary' nuclear burning - Neutron star deflagration?

NASA Technical Reports Server (NTRS)

Michel, F. Curtis

1988-01-01

A motivation is presented for the idea that dense nuclear matter can burn to a new class of stable particles. One of several possibilities is an 'octet' particle which is the 16 baryon extension of alpha particle, but now composed of a pair of each of the two nucleons, (3Sigma, Delta, and 2Xi). Such 'tertiary' nuclear burning (here 'primary' is H-He and 'secondary' is He-Fe) may lead to neutron star explosions rather than collapse to a black hole, analogous to some Type I supernovae models wherein accreting white dwarfs are pushed over the Chandrasekhar mass limit but explode rather than collapse to form neutron stars. Such explosions could possibly give gamma-ray bursts and power quasars, with efficient particle acceleration in the resultant relativistic shocks. The new stable particles themselves could possibly be the sought-after weakly interacting, massive particles (WIMPs) or 'dark' matter.

Multiquadrant robotic colorectal surgery: the da Vinci Xi vs Si comparison.

PubMed

Protyniak, Bogdan; Jorden, Jeffrey; Farmer, Russell

2018-03-01

The newly introduced da Vinci Xi Surgical System hopes to address the shortcomings of its predecessor, specifically robotic arm restrictions and difficulty working in multiple quadrants. We compare the two robot platforms in multiquadrant surgery at a major colorectal referral center. Forty-four patients in the da Vinci Si group and 26 patients in the Xi group underwent sigmoidectomy or low anterior resection between 2014 and 2016. Patient demographics, operative variables, and postoperative outcomes were compared using descriptive statistics. Both groups were similar in age, sex, BMI, pelvic surgeries, and ASA class. Splenic flexure was mobilized in more (p = 0.045) da Vinci Xi cases compared to da Vinci Si both for sigmoidectomy (50 vs 15.4%) and low anterior resection (60 vs 29%). There was no significant difference in operative time (219.9 vs 224.7 min; p = 0.640), blood loss (170.0 vs 188.1 mL; p = 0.289), length of stay (5.7 vs 6 days; p = 0.851), or overall complications (26.9 vs 22.7%; p = 0.692) between the da Vinci Xi and Si groups, respectively. Single-dock multiquadrant robotic surgery, measured by splenic flexure mobilization with concomitant pelvic dissection, was more frequently performed using the da Vinci Xi platform with no increase in operative time, bleeding, or postoperative complications. The new platform provides surgeons an easier alternative to the da Vinci Si dual docking or combined robotic/laparoscopic multiquadrant surgery.

Enhanced photovoltaic performance of CH3NH3PbBrXI3-X-based perovskite solar cells via anti-solvent extraction

NASA Astrophysics Data System (ADS)

Jiang, Zhaoyi; Zhang, Weijia; Lu, Chaoqun; Ma, Denghao; Liu, Haixu; Yu, Wei; Zhang, Yu; Ma, Qiang; Zhang, Yulong

2018-06-01

In this paper, the two-step sequential deposition method was used to prepare the CH3NH3PbBrXI3-X films by introducing CH3NH3Br in the precursors. The surface morphology of the PbI2 films was controlled by anti-solvent extraction (ASE) to improve the microstructure and photo-physical properties of the perovskite films. It was noteworthy that, compared to the compact PbI2 films, the porous PbI2 films facilitated the growth of crystals and bromine incorporation in films, and the prepared perovskite films exhibited enlarged grain size, increased light absorption, enhanced Br incorporation and prolonged carrier lifetime, which resulted in excellent photo-electrical properties of the CH3NH3PbBrXI3-X films. With porous PbI2 templates, the inverted planar perovskite solar cells based on films with appropriate Br incorporation (CH3NH3Br/CH3NH3I mole ratio = 3/7) showed a photovoltaic conversion efficiency (PCE) of 14.9%, and the stability of the devices in air was elevated. Consequently, the high-quality CH3NH3PbBrXI3-X films can be obtained with porous PbI2 templates for improving the performance of the perovskite solar cells.

Study of the strong {sigma}{sub c}{yields}{lambda}{sub c}{pi},{sigma}{sub c}*{yields}{lambda}{sub c}{pi} and {xi}{sub c}*{yields}{xi}{sub c}{pi} decays in a nonrelativistic quark model

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

Albertus, C.; Nieves, J.; Hernandez, E.

We present results for the strong widths corresponding to the {sigma}{sub c}{yields}{lambda}{sub c}{pi}, {sigma}{sub c}*{yields}{lambda}{sub c}{pi} and {xi}{sub c}*{yields}{xi}{sub c}{pi} decays. The calculations have been done in a nonrelativistic constituent quark model with wave functions that take advantage of the constraints imposed by heavy quark symmetry. Partial conservation of axial current hypothesis allows us to determine the strong vertices from an analysis of the axial current matrix elements. Our results {gamma}({sigma}{sub c}{sup ++}{yields}{lambda}{sub c}{sup +}{pi}{sup +})=2.41{+-}0.07{+-}0.02 MeV, {gamma}({sigma}{sub c}{sup +}{yields}{lambda}{sub c}{sup +}{pi}{sup 0})=2.79{+-}0.08{+-}0.02 MeV, {gamma}({sigma}{sub c}{sup 0}{yields}{lambda}{sub c}{sup +}{pi}{sup -})=2.37{+-}0.07{+-}0.02 MeV, {gamma}({sigma}{sub c}*{sup ++}{yields}{lambda}{sub c}{sup +}{pi}{sup +})=17.52{+-}0.74{+-}0.12 MeV, {gamma}({sigma}{sub c}*{supmore » +}{yields}{lambda}{sub c}{sup +}{pi}{sup 0})=17.31{+-}0.73{+-}0.12 MeV, {gamma}({sigma}{sub c}*{sup 0}{yields}{lambda}{sub c}{sup +}{pi}{sup -})=16.90{+-}0.71{+-}0.12 MeV, {gamma}({xi}{sub c}*{sup +}{yields}{xi}{sub c}{sup 0}{pi}{sup +}+{xi}{sub c}{sup +}{pi}{sup 0})=3.18{+-}0.10{+-}0.01 MeV, and {gamma}({xi}{sub c}*{sup 0}{yields}{xi}{sub c}{sup +}{pi}{sup -}+{xi}{sub c}{sup 0}{pi}{sup 0})=3.03{+-}0.10{+-}0.01 MeV are in good agreement with experimental determinations.« less

Factor XI and XII as antithrombotic targets.

PubMed

Müller, Felicitas; Gailani, David; Renné, Thomas

2011-09-01

Arterial and venous thrombosis are major causes of morbidity and mortality, and the incidence of thromboembolic diseases increases as a population ages. Thrombi are formed by activated platelets and fibrin. The latter is a product of the plasma coagulation system. Currently available anticoagulants such as heparins, vitamin K antagonists and inhibitors of thrombin or factor Xa target enzymes of the coagulation cascade that are critical for fibrin formation. However, fibrin is also necessary for terminating blood loss at sites of vascular injury. As a result, anticoagulants currently in clinical use increase the risk of bleeding, partially offsetting the benefits of reduced thrombosis. This review focuses on new targets for anticoagulation that are associated with minimal or no therapy-associated increased bleeding. Data from experimental models using mice and clinical studies of patients with hereditary deficiencies of coagulation factors XI or XII have shown that both of these clotting factors are important for thrombosis, while having minor or no apparent roles in processes that terminate blood loss (hemostasis). Hereditary deficiency of factor XII (Hageman factor) or factor XI, plasma proteases that initiate the intrinsic pathway of coagulation, impairs thrombus formation and provides protection from vascular occlusive events, while having a minimal impact on hemostasis. As the factor XII-factor XI pathway contributes to thrombus formation to a greater extent than to normal hemostasis, pharmacological inhibition of these coagulation factors may offer the exciting possibility of anticoagulation therapies with minimal or no bleeding risk.

SiC-based neutron detector in quasi-realistic working conditions: efficiency and stability at room and high temperature under fast neutron irradiations

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

Ferone, Raffaello; Issa, Fatima; Ottaviani, Laurent

In the framework of the European I SMART project, we have designed and made new SiC-based nuclear radiation detectors able to operate in harsh environments and to detect both fast and thermal neutrons. In this paper, we report experimental results of fast neutron irradiation campaign at high temperature (106 deg. C) in quasi-realistic working conditions. Our device does not suffer from high temperature, and spectra do show strong stability, preserving features. These experiments, as well as others in progress, show the I SMART SiC-based device skills to operate in harsh environments, whereas other materials would strongly suffer from degradation. Workmore » is still demanded to test our device at higher temperatures and to enhance efficiency in order to make our device fully exploitable from an industrial point of view. (authors)« less

Detection of a compact companion of the mild barium star Xi-1 Ceti

NASA Technical Reports Server (NTRS)

Bohm-Vitense, E.; Johnson, H. R.

1985-01-01

In the present paper, the observation of a white dwarf companion of the mild Ba star Xi-1 Ceti (= 65 Ceti = HR 649 = HD 13611) is reported, taking into account also the properties of the mild Ba star and of its companion. The UV spectrum of Xi-1 Ceti is discussed along with an interpretation of this spectrum. Attention is given to the effective temperature of the companion, the absorption bands in the spectrum, the radius and mass of the Xi-1 Ceti companion, and questions regarding the obscuration of the companion by the atmosphere of the Ba star. It is found that the overall energy distribution of the Xi-1 Ceti companion can best be matched with a 14,000 K DA white dwarf of log g = 8 or less. However, the absolute intensity is too small and would require a radius too small and a mass too large for such a gravity.

The Obama - Xi Accord: A Need for Further Action

NASA Astrophysics Data System (ADS)

Tribett, W. R.; Hope, A. P.; Canty, T. P.; Salawitch, R. J.

2015-12-01

Presidents Barrack Obama of the United States and Jinping Xi of China recently announced a bilateral framework to reduce the total carbon emissions of their respective countries. The U.S. agreed to reduce annual carbon emissions such that by 2025, emissions would be 27% below 2005 levels. China agreed to achieve peak carbon emissions around 2030 coupled with a best effort to peak early. Here we analyze the implications of the Obama-Xi accord for total global carbon emissions (GCE) out to year 2060, using projections of population, economic growth, and carbon intensity for the rest of the world as well as various assumptions regarding how emissions from the U.S. and China will evolve after the timeframe of the Obama-Xi accord. Our GCE projections will be compared to those of the four Representative Concentration Pathway (RCP) emission scenarios used in the IPCC Fifth Assessment Report (AR5). The Obama-Xi accord is shown to be a meaningful first step: if followed, the actual GCE will likely fall below RCP 8.5 between now and 2060. The U.S., China, and rest of the world presently emit 4.5, 2.0, and 1.1 tonne of carbon per person per year (tpy), respectively. We show that if the world's nations adopt a strategy of "Contraction and Convergence", such that per capita emission for each country reaches 1.0 tpy by 2060, actual GCE will approach that of RCP 4.5 by year 2060. Such action may be needed to reduce the risk of the most dire global warming forecasts within IPCC AR5.

2017 Scientific Sessions Sol Sherry Distinguished Lecture in Thrombosis: Factor XI as a Target for New Anticoagulants.

PubMed

Weitz, Jeffrey I; Fredenburgh, James C

2018-02-01

The goal of anticoagulant therapy is to attenuate thrombosis without compromising hemostasis. Although the direct oral anticoagulants are associated with less intracranial hemorrhage than vitamin K antagonists, bleeding remains their major side effect. Factor XI has emerged as a promising target for anticoagulants that may be safer than those currently available. The focus on factor XI stems from epidemiological evidence of its role in thrombosis, the observation of attenuated thrombosis in factor XI-deficient mice, identification of novel activators, and the fact that factor XI deficiency is associated with only a mild bleeding diathesis. Proof-of-concept comes from the demonstration that compared with enoxaparin, factor XI knockdown reduces venous thromboembolism without increasing bleeding after elective knee arthroplasty. This article rationalizes the selection of factor XI as a target for new anticoagulants, reviews the agents under development, and outlines a potential path forward for their development. © 2017 American Heart Association, Inc.

Level structure and production cross section of {sub {Xi}}{sup 12} Be studied with coupled-channels antisymmetrized molecular dynamics

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

Matsumiya, H.; Tsubakihara, K.; Kimura, M.

A theoretical framework of coupled-channels antisymmetrized molecular dynamics that describes the multistrangeness system with mixing between different baryon species is developed and applied to {sub {Lambda}}{sup 12}C and {sub {Xi}}{sup 12}Be. By introducing a minor modification to the YN G-matrix interaction derived from the Nijmegen model-D, the low-lying level structure and production cross section of {sub {Lambda}}{sup 12}C are reasonably described. It is found that the low-lying states of {sub {Xi}}{sup 12}Be are dominated by the {sup 11}B {circle_times} {Xi}{sup -} channel and their order strongly depends on {Xi}N effective interactions used in the calculation. The calculated peak position ofmore » the production cross section depends on the {Xi}N effective interaction and the magnitude of spin-flip and non-spin-flip cross sections of K{sup -}p{yields}K{sup +}{Xi}{sup -} elemental processes. We suggest that the {sup 12}C(K{sup -},K{sup +}){sub {Xi}}{sup 12}Be reaction possibly provides us information about the {Xi}N interaction.« less

42 CFR 476.86 - Correlation of Title XI functions with Title XVIII functions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 4 2011-10-01 2011-10-01 false Correlation of Title XI functions with Title XVIII functions. 476.86 Section 476.86 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF...) Qio Review Functions § 476.86 Correlation of Title XI functions with Title XVIII functions. (a...

Da Vinci Xi and Si platforms have equivalent perioperative outcomes during robot-assisted partial nephrectomy: preliminary experience.

PubMed

Abdel Raheem, Ali; Sheikh, Abulhasan; Kim, Dae Keun; Alatawi, Atalla; Alabdulaali, Ibrahim; Han, Woong Kyu; Choi, Young Deuk; Rha, Koon Ho

2017-03-01

The aims of this study were to compare the perioperative outcomes of da Vinci Xi to Si during robotic-assisted partial nephrectomy (RAPN) and to discuss the feasibility of our novel port placement scheme for the da Vinci Xi platform, to overcome the existing kinetic and technical difficulties we faced with the linear port placement in patients with a small body habitus. A retrospective data analysis of patients who underwent RPN using da Vinci Xi (n = 18) was carried out. The outcomes of the Xi group were compared with the Si group (n = 18) selected using a case-matched methodology. For da Vinci Xi, we applied the universal linear port placement in 12 patients and our modified port placement in the remaining 6 patients. The Xi group had a shorter mean docking time of 17.8 ± 2.6 min compared to the Si group of 20.5 ± 2.1 min (p = 0.002); otherwise, no significant difference was present with regard to the remaining perioperative variables (p > 0.05). The modified Xi port placement had a shorter mean console time of 70.8 ± 9.7 min compared to the universal linear port placement of 89.3 ± 17.2 min (p = 0.03). Moreover, it provided a broader field of vision with excellent robotic arms movement, minimizing collisions and allowing an easier and comfortable surgical assist. Da Vinci Xi appears to be feasible and safe during RPN with similar outcomes to Si. The novel Xi port placement makes surgery easier in patients with low BMI.

Factor XI and Contact Activation as Targets for Antithrombotic Therapy

PubMed Central

Gailani, David; Bane, Charles E.; Gruber, Andras

2015-01-01

Summary The most commonly used anticoagulants produce therapeutic antithrombotic effects either by inhibiting thrombin or factor Xa, or by lowering the plasma levels of the precursors of these key enzymes, prothrombin and factor X. These drugs do not distinguish between thrombin generation contributing to thrombosis from thrombin generation required for hemostasis. Thus, anticoagulants increase bleeding risk, and many patients who would benefit from therapy go untreated because of comorbidities that place them at unacceptable risk for hemorrhage. Studies in animals demonstrate that components of the plasma contact activation system contribute to experimentally-induced thrombosis, despite playing little or no role in hemostasis. Attention has focused on factor XII, the zymogen of a protease (factor XIIa) that initiates contact activation when blood is exposed to foreign surfaces; and factor XI, the zymogen of the protease factor XIa, which links contact activation to the thrombin generation mechanism. In the case of factor XI, epidemiologic data indicate this protein contributes to stroke and venous thromboembolism, and perhaps myocardial infarction, in humans. A phase 2 trial showing that reduction of factor XI may be more effective than low-molecular-weight heparin at preventing venous thrombosis during knee replacement surgery provides proof of concept for the premise that an antithrombotic effect can be uncoupled from an anticoagulant effect in humans by targeting components of contact activation. Here we review data on the role of factor XI and factor XII in thrombosis, and results of pre-clinical and human trials for therapies targeting these proteins. PMID:25976012

OMEGA{sup -}, XI*{sup -}, SIGMA*{sup -}, and DELTA{sup -} decuplet baryon magnetic moments

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

Slaughter, Milton Dean

The properties of the ground-state U spin =(3/2) baryon decuplet magnetic moments DELTA{sup -}, XI*{sup -}, SIGMA*{sup -}, and OMEGA{sup -} and their ground-state spin-(1/2) cousins p, n, LAMBDA, SIGMA{sup +}, SIGMA{sup 0}, SIGMA{sup -}, XI{sup +}, and XI{sup -} have been studied for many years with a modicum of success. The magnetic moments of many are yet to be determined. Of the decuplet baryons, only the magnetic moment of the OMEGA{sup -} has been accurately determined. We calculate the magnetic moments of the physical decuplet U spin =(3/2) quartet members without ascribing any specific form to their quark structuremore » or intraquark interactions.« less

Deteriorating haze situation and the severe haze episode during December 18-25 of 2013 in Xi'an, China, the worst event on record

NASA Astrophysics Data System (ADS)

Liu, Xiaodong; Hui, Ying; Yin, Zhi-Yong; Wang, Zhaosheng; Xie, Xiaoning; Fang, Jiangang

2016-07-01

Frequent occurrence of haze weather has been considered an urgent environmental problem in China and has attracted much attention worldwide in recent years. In this study, we examined the trend in the occurrence of haze days based on horizontal visibility in Xi'an, a major city in central China, since 2000. There were 49 haze days per year on average in Xi'an during 2000-2013, and the number of haze days has increased significantly since 2008, reaching 102 days in 2013. December is the month of the highest frequency of occurrence. During December 18-25 of 2013, the longest-lasting and most severe haze event in the recent decades occurred. The 8-day mean visibility in Xi'an was only 2.5 km with 5 days below 2 km. The mean air quality index in Xi'an during this period was 486.5, and in four of those days, it reached or exceeded the index's upper limit of 500. The exceptionally high level of PM2.5 concentration was inferred as the main reason of this severe haze episode. The local weather conditions were characterized by weak winds, enhanced atmospheric stability, and high relative humidity. Strong mid-tropospheric zonal flows in combination with weakened East Asian winter monsoon limited the cold air invasion from the higher latitudes, creating a condition of low pressure gradients in the lower troposphere and near the surface for a large region in central and eastern China. With high background emission levels, the suppressed dispersion of air pollutants eventually caused this severe haze episode affecting a large region in China.

Study on collaborative operation in Xi'an international inland port and airport

NASA Astrophysics Data System (ADS)

Jia, Guoling

2017-10-01

Xi 'an international inland port and airport are the important fulcrums for Shaanxi province to implement the strategy of "One Belt One Road" and to develop its export-oriented economy. Based on the general development situation of Xi 'an international inland port and airport and analyzing their similarities and differences, the external cause and internal cause of synergy are discussed. The contents of synergy from the strategy level, tactics level and business level are explained respectively.

Educational Pico-Satellite Project CUBESAT - University of Tokyo's CUBESAT XI and its Operation Plan

NASA Astrophysics Data System (ADS)

Tsuda, Y.; Sako, N.; Eishima, T.; Ito, T.; Arikawa, Y.; Miyamura, N.

2002-01-01

University of Tokyo ISSL (Intelligent Space Systems Laboratory) has been developing a pico-satellite called "CubeSat" as an international joint program. In CubeSat project, 10cm cubic satellites have been developed by several universities and launched to the low-earth orbit altogether by Russian rocket "Dnepr". ISSL has developed "XI" series ([sai]: X-factor Investigator) satellites, and the flight model is already fabricated and ready for delivery. The mission of XI satellite is the on-orbit technology demonstration of the ultra-small satellite bus system with an extensive use of commercial-off-the-shelf components. XI transmits the Morse beacon and FM packet telemetry which provides the health data of the satellite. Additionally, XI has a CMOS camera which provides 15,000 pixels panchromatic images as an advanced mission. Ground operation is one of the key issues for CubeSats. Now we are promoting international ground station network in which several universities' ground stations connected by internet collaboratively operate university-built small satellites, which enlarges the link opportunity. Collaboration with amateur HAM engineers is also indispensable for search for the satellite or get beacon signal to estimate the satellite orbit. We are now developing operation concept based on these ideas. As the launch is scheduled in this fall, the operation plan will be fixed at the time of this conference. In this presentation the final design of ISSL's CubeSat XI and operation plan will be presented.

Early clinical experience with the da Vinci Xi Surgical System in general surgery.

PubMed

Hagen, Monika E; Jung, Minoa K; Ris, Frederic; Fakhro, Jassim; Buchs, Nicolas C; Buehler, Leo; Morel, Philippe

2017-09-01

The da Vinci Xi Surgical System (Intuitive Surgical Inc., Sunnyvale, CA, USA) has been released in 2014 to facilitate minimally invasive surgery. Novel features are targeted towards facilitating complex multi-quadrant procedures, but data is scarce so far. Perioperative data of patients who underwent robotic general surgery with the da Vinci Xi system within the first 6 month after installation were collected and analyzed. The gastric bypass procedures performed with the da Vinci Xi Surgical System were compared to an equal amount of the last procedures with the da Vinci Si Surgical System. Thirty-one foregut (28 Roux-en-Y gastric bypasses), 6 colorectal procedures and 1 revisional biliary procedure were performed. The mean operating room (OR) time was 221.8 (±69.0) minutes for gastric bypasses and 306.5 (±48.8) for colorectal procedures with mean docking time of 9.4 (±3.8) minutes. The gastric bypass procedure was transitioned from a hybrid to a fully robotic approach. In comparison to the last 28 gastric bypass procedures performed with the da Vinci Si Surgical System, the OR time was comparable (226.9 versus 230.6 min, p = 0.8094), but the docking time significantly longer with the da Vinci Xi Surgical System (8.5 versus 6.1 min, p = 0.0415). All colorectal procedures were performed with a single robotic docking. No intraoperative and two postoperative complications occurred. The da Vinci Xi might facilitate single-setups of totally robotic gastric bypass and colorectal surgeries. However, further comparable research is needed to clearly determine the significance of this latest version of the da Vinci Surgical System.

Multistage position-stabilized vibration isolation system for neutron interferometry

NASA Astrophysics Data System (ADS)

Arif, Muhammad; Brown, Dennis E.; Greene, Geoffrey L.; Clothier, R.; Littrell, K.

1994-10-01

A two stage, position stabilized vibration isolation system has been constructed and is now in operation at the Cold Neutron Research Facility of the National Institute of Standards and Technology, Gaithersburg, MD. The system employs pneumatic isolators with a multiple input/multiple output pneumatic servo system based upon pulse width modulation control loops. The first stage consists of a 40,000 kg reinforced concrete table supported by pneumatic isolators. A large environmentally isolated laboratory enclosure rests on the concrete table. The second stage consists of a 3000 kg granite optical table located within the enclosure and supported by another set of pneumatic isolators. The position of the two stages is monitored by proximity sensors and inclinometers with 12 degrees of freedom. The system controls 12 independent pneumatic airsprings. The signals from these sensors are fed into a personal computer based control system. The control system has maintained the position of the two stages to better than 1 micrometers in translation and 5 (mu) rad in orientation for a period of a few months. A description of the system and its characteristics is given.

Origin of the incommensurate phase of quartz: I. Inelastic neutron scattering study of the high temperature β phase of quartz

NASA Astrophysics Data System (ADS)

Dolino, G.; Berge, B.; Vallade, M.; Moussa, F.

1992-07-01

The origin of the incommensurate phase of quartz is attributed to a gradient interaction between the optical soft mode of the α-β transition of quartz and a transverse acoustic mode. To test this model high resolution inelastic neutron scattering studies of the lattice dynamics of quartz have been performed. For the first time, a resolved zone center soft mode has been observed in the β phase of quartz at 1 THz at 1 250 K, confirming the displacive character of this transition. Along [xi 0 0] a strong interaction has been observed between this soft mode and the acoustic branch with u_{xy} shear strain. The softening of the two mixed branches produced by this interaction has been followed by decreasing temperature. Near the transition a dip appears in the lower frequency branch, which goes continuously to 0 near xi=0.035 at the incommensurate phase transition. Due to a large damping, the soft branch is overdamped near the transition leading to a quasielastic peak. Along [ xi xi 0] where the soft mode is coupled with the longitudinal acoustic mode, no dip is observed in the lower frequency mode. These results are in good agreement with the predictions of the gradient interaction model discussed in the following paper. L'existence de la phase incommensurable du quartz est attribuée à une interaction entre le gradient du mode mou optique de la transition α β et un mode acoustique transverse. Pour vérifier ce modèle, des mesures de diffusion inélastique des neutrons, de haute résolution, ont été faites. Un mode mou résolu en centre de zone a, pour la première fois, été observé vers 1 THz à 1 250 K, dans la phase β du quartz, confirmant le caractère displacif de cette transition. Le long de [ xi 0 0] , une forte interaction est observée entre ce mode mou et la branche acoustique ayant une déformation de cisaillement u_{xy}. L'amollissement des deux branches mixtes, résultant de cette interaction, a été suivi en fonction de la température. Pr

Use of a mobile tower-based robot--The initial Xi robot experience in surgical oncology.

PubMed

Yuh, Bertram; Yu, Xian; Raytis, John; Lew, Michael; Fong, Yuman; Lau, Clayton

2016-01-01

The da Vinci Xi platform provides expanded movement of the arms relative to the base, theoretically allowing increased versatility in complex multi-field or multi-quadrant surgery. We describe the initial Xi experience in oncologic surgery at a tertiary cancer center. One hundred thirty unique robot-assisted procedures were performed using the Xi between 2014 and 2015, 112 of which were oncology surgeries. For procedures involving multiple quadrants, the robot was re-targeted. Complications were assessed according to Martin criteria and the Clavien-Dindo classification up to 90 days after operation. Thirteen different operations were performed in five oncology subspecialties (urology, gynecology, thoracic, hepatobiliary, and gastrointestinal surgery). Median operative times ranged from 183 min for nephroureterectomy to 543 min for esophagogastrectomy. Median estimated blood loss did not exceed 200 ml for any of the categorized procedures . No patients were transfused intraoperatively and no positioning injuries occurred. Conversions to open operation occurred in three cases (2.7%), though not related to complications or technical considerations. Overall complication rate was 26% with major complication rate of 4%. Readmissions were necessary in 11 (10%) patients. The da Vinci Xi can be safely assimilated into a surgical oncology program. The Xi offers versatility to various oncologic procedures with satisfactory complication and readmission rates. © 2015 Wiley Periodicals, Inc.

Robotic da Vinci Xi-assisted nipple-sparing mastectomy: First clinical report.

PubMed

Sarfati, Benjamin; Honart, Jean-Francois; Leymarie, Nicolas; Rimareix, Francoise; Al Khashnam, Heba; Kolb, Frederic

2018-05-01

Nipple-sparing mastectomy (NSM) is increasingly popular for the treatment of selected breast cancers and prophylactic mastectomy. Surgical scarring and esthetic outcomes are important patient-related cosmetic considerations. Today, the concept of minimally invasive surgery has become popular, especially using robotic surgery. The authors report the first case of NSM using the latest version of the da Vinci Xi surgical system (Xi). The final incision used to remove the entire mammary gland was located behind the axillary line. In this position, hidden by the arm of the patient, the incision was not visible and was compatible with immediate breast reconstruction. © 2017 Wiley Periodicals, Inc.

Distribution and source analysis of aluminum in rivers near Xi'an City, China.

PubMed

Wang, Dongqi; He, Yanling; Liang, Jidong; Liu, Pei; Zhuang, Pengyu

2013-02-01

To study the status and source of aluminum (Al) contamination, a total of 21 sampling sites along six rivers near Xi'an City (Shaanxi province, China) were investigated during 2008-2010. The results indicated that the average concentration of total Al (Al(t)) in the six rivers increased by 1.6 times from 2008 to 2010. The spatial distribution of Al(t) concentrations in the rivers near Xi'an City was significantly different, ranged from 367 μg/L (Bahe River) to 1,978 μg/L (Taiping River). The Al(t) concentration was highest near an industrial area for pulp and paper-making (2,773 μg/L), where the Al level greatly exceeded the water quality criteria of both the USA (Criterion Continuous Concentration, 87 μg/L) and Canada (100 μg/L). The average concentration of inorganic monometric aluminum (Al(im)) was 72 μg/L which would pose threats to fishes and other aquatic lives in the rivers. The concentrations of exchangeable Al (Al(ex)) in the sediment of the Taiping River sampled were relatively high, making it to be an alternative explanation of increasing Al concentrations in the rivers near Xi'an City. Furthermore, an increasing Al level has been detected in the upstream watershed near Xi'an City in recent years, which might indicate another notable pollution source of Al.

Monitoring on Xi'an ground fissures deformation with TerraSAR-X data

USGS Publications Warehouse

Zhao, C.; Zhang, Q.; Zhu, W.; Lu, Z.

2012-01-01

Owing to the fine resolution of TerraSAR-X data provided since 2007, this paper applied 6 TerraSAR data (strip mode) during 3rd Dec. 2009 to 23rd Mar. 2010 to detect and monitor the active fissures over Xi'an region. Three themes have been designed for high precision detection and monitoring of Xi'an-Chang'an fissures, as small baseline subsets (SBAS) to test the atmospheric effects of differential interferograms pair stepwise, 2-pass differential interferogram with very short baseline perpendicular to generate the whole deformation map with 44 days interval, and finally, corner reflector (CR) technique was used to closely monitor the relative deformation time series between two CRs settled crossing two ground fissures. Results showed that TerraSAR data are a good choice for small-scale ground fissures detection and monitoring, while special considerations should be taken for their great temporal and baseline decorrelation. Secondly, ground fissures in Xi'an were mostly detected at the joint section of stable and deformable regions. Lastly, CR-InSAR had potential ability to monitor relative deformation crossing fissures with millimeter precision.

[HIV/STD prevalence and related behaviors among male STD clinic attendees in Xi'an and Xianyang cities, Shaanxi province].

PubMed

Hu, T; Dong, L F; Ding, Z W; Jia, H; Li, X; Zhang, J S; Song, Y L; Chang, W H

2017-12-10

Objective: To compare the prevalence of HIV/STD and related health care seeking behaviors among male STD clinic attendees between Xi'an and Xianyang cities. Methods: During June and July 2016, 206 male STD clinic attendees were studied in Xi'an city, with another 221 male STD clinic attendees in Xianyang city. Cross-sectional questionnaire survey was used to collect attendees'behavioral information. Blood samples were collected via HIV/HCV/Syphilis testing. Results: The prevalence rate of HIV infection was 2.4% (5/206) in Xi'an and 0.9% (2/221) in Xianyang, with no statistical significant difference between the two cities. The prevalence rate of syphilis was 4.9% (10/206) in Xi'an, which was significantly lower than 13.6% (30/221) in Xianyang. The proportion of respondents, diagnosed with other sexually transmitted diseases, in Xi'an was higher than that of Xianyang. The proportions of commercial heterosexual sex and sex with temporary sexual partners in the past 3 months were 18.0% (37/206) and 15.5% (32/206) in Xi'an, lower than 46.6% (103/221) and 15.8% (35/221) in Xianyang ( χ (2)=39.70, Р <0.01; χ (2)=0.01, P =0.93) . The proportions of condom use with commercial sex workers or temporary sexual partners in the past 3 months among Xi'an were 37.8% (14/37) and 6.3% (2/32) , lower than 93.1% (95/102) and 57.1% (20/35) in Xianyang ( χ (2)=49.06, Р <0.01; χ (2)=19.63, Р <0.01) . Conclusion: Differences were noticed between Xi'an and Xianyang city in terms of STD and HIV prevalences, behaviors related to commercial sex and use of condoms among the male STD clinic attendees that calling for targeted actions in control of high risk behavlors in both HIV/AIDS and STDs transmission.

Operative technique and early experience for robotic-assisted laparoscopic nephroureterectomy (RALNU) using da Vinci Xi.

PubMed

Darwiche, Fadi; Swain, Sanjaya; Kallingal, George; Punnen, Sanoj; Manoharan, Murugesan; Parekh, Dipen J; Gonzalgo, Mark L

2015-01-01

Robotic-assisted laparoscopic nephroureterectomy (RALNU) has been previously utilized for management of upper tract urothelial carcinoma. The da Vinci Xi surgical system was released in April of 2014. We describe our operative technique and early experience for RALNU using the da Vinci Xi system highlighting unique features of this surgical platform. A total of 10 patients with a diagnosis of upper tract urothelial carcinoma underwent RALNU using the da Vinci Xi system between April and November of 2014. A novel, oblique "in line" robotic trocar configuration was utilized to access the upper abdomen (nephrectomy portion) and pelvis (bladder cuff excision) without undocking. The port hopping feature of da Vinci Xi was utilized to facilitate optimal, multi-quadrant visualization during RALNU. Robotic-assisted laparoscopic nephroureterectomy was successfully completed without open conversion in all 10 patients. Mean operative time was 184 min (range 140-300 min), mean estimated blood loss was 121 cc (range 60-300 cc), and mean hospital stay was 2.4 days. Final pathology demonstrated high grade urothelial carcinoma in all patients. Surgical margins were negative in all patients. No intra-operative complications were encountered. One patient developed a pulmonary embolus after being discharged. No patients required a blood transfusion. Mean patient follow-up was 130 days (range 15-210 days). The use of da Vinci Xi with a novel, oblique "in line" port configuration and camera port hopping technique allows for an efficient and reproducible method for RALNU without the need for repositioning the patient or the robot during surgery.

25 CFR 36.31 - Standard XI-Student promotion requirements.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 25 Indians 1 2012-04-01 2011-04-01 true Standard XI-Student promotion requirements. 36.31 Section 36.31 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR EDUCATION MINIMUM ACADEMIC STANDARDS FOR THE BASIC EDUCATION OF INDIAN CHILDREN AND NATIONAL CRITERIA FOR DORMITORY SITUATIONS Student...

25 CFR 36.31 - Standard XI-Student promotion requirements.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 25 Indians 1 2011-04-01 2011-04-01 false Standard XI-Student promotion requirements. 36.31 Section 36.31 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR EDUCATION MINIMUM ACADEMIC STANDARDS FOR THE BASIC EDUCATION OF INDIAN CHILDREN AND NATIONAL CRITERIA FOR DORMITORY SITUATIONS Student...

Cloning and characterization of XiR1, a locus responsible for dagger nematode resistance in grape.

PubMed

Hwang, Chin-Feng; Xu, Kenong; Hu, Rong; Zhou, Rita; Riaz, Summaira; Walker, M Andrew

2010-08-01

The dagger nematode, Xiphinema index, feeds aggressively on grape roots and in the process, vectors grapevine fanleaf virus (GFLV) leading to the severe viral disease known as fanleaf degeneration. Resistance to X. index and GFLV has been the key objective of grape rootstock breeding programs. A previous study found that resistance to X. index derived from Vitis arizonica was largely controlled by a major quantitative trait locus, XiR1 (X. index Resistance 1), located on chromosome 19. The study presented here develops high-resolution genetic and physical maps in an effort to identify the XiR1 gene(s). The mapping was carried out with 1,375 genotypes in three populations derived from D8909-15, a resistant selection from a cross of V. rupestris A. de Serres (susceptible) x V. arizonica b42-26 (resistant). Resistance to X. index was evaluated on 99 informative recombinants that were identified by screening the three populations with two markers flanking the XiR1 locus. The high-resolution genetic map of XiR1 was primarily constructed with seven DNA markers developed in this study. Physical mapping of XiR1 was accomplished by screening three bacterial artificial chromosome (BAC) libraries constructed from D8909-15, V. vinifera Cabernet Sauvignon and V. arizonica b42-26. A total of 32 BAC clones were identified and the XiR1 locus was delineated within a 115 kb region. Sequence analysis of three BAC clones identified putative nucleotide binding/leucine-rich repeat (NB-LRR) genes. This is the first report of a closely linked major gene locus responsible for ectoparasitic nematode resistance. The markers developed from this study are being used to expedite the breeding of resistant grape rootstocks.

Cloning and characterization of XiR1, a locus responsible for dagger nematode resistance in grape

PubMed Central

Hwang, Chin-Feng; Xu, Kenong; Hu, Rong; Zhou, Rita; Riaz, Summaira

2010-01-01

The dagger nematode, Xiphinemaindex, feeds aggressively on grape roots and in the process, vectors grapevine fanleaf virus (GFLV) leading to the severe viral disease known as fanleaf degeneration. Resistance to X. index and GFLV has been the key objective of grape rootstock breeding programs. A previous study found that resistance to X. index derived from Vitis arizonica was largely controlled by a major quantitative trait locus, XiR1 (X. index Resistance 1), located on chromosome 19. The study presented here develops high-resolution genetic and physical maps in an effort to identify the XiR1 gene(s). The mapping was carried out with 1,375 genotypes in three populations derived from D8909-15, a resistant selection from a cross of V. rupestris A. de Serres (susceptible) × V. arizonica b42-26 (resistant). Resistance to X. index was evaluated on 99 informative recombinants that were identified by screening the three populations with two markers flanking the XiR1 locus. The high-resolution genetic map of XiR1 was primarily constructed with seven DNA markers developed in this study. Physical mapping of XiR1 was accomplished by screening three bacterial artificial chromosome (BAC) libraries constructed from D8909-15, V. vinifera Cabernet Sauvignon and V. arizonica b42-26. A total of 32 BAC clones were identified and the XiR1 locus was delineated within a 115 kb region. Sequence analysis of three BAC clones identified putative nucleotide binding/leucine-rich repeat (NB-LRR) genes. This is the first report of a closely linked major gene locus responsible for ectoparasitic nematode resistance. The markers developed from this study are being used to expedite the breeding of resistant grape rootstocks. PMID:20490447

Ground Subsidence Monitoring with MT-InSAR and Mechanism Inversion Over Xi'an, China

NASA Astrophysics Data System (ADS)

Peng, M. M.; Zhao, C. Y.; Zhang, Q.; Zhang, J.; Liu, Y. Y.

2018-04-01

The ancient Xi'an, China, has been suffering severe land subsidence and ground fissure hazards since the 1960s, which has affected the safety of Subways. Multi-sensor SAR data are conducted to monitor the latest complex ground deformation and its influence on subway line No.3 over Xi'an. Annual deformation rates have been retrieved to reveal the spatiotemporal evolution of ground subsidence in Xi'an city from 2013 to 2017. Meanwhile, the correlation between land subsidence and ground fissures are analyzed by retrieving the deformation differences in both sides of the fissures. Besides, the deformation along subway line No. 3 is analyzed, and the fast deformation section is quantitatively studied. Finally, a flat lying sill model with distributed contractions is implemented to model the InSAR deformation over YHZ subsidence center, which manifests that the ground deformation is mainly caused by groundwater withdrawal.

[Heavy metals pollution and analysis of seasonal variation runoff in Xi'an].

PubMed

Yuan, Hong-Lin; Li, Xing-Yu; Wang, Xiao-Chang

2014-11-01

In order to explore heavy metals pollution situation,changes in characteristics, the correlation between each heavy mental and pollution source analysis of Xi'an various regions in different season in one year. This study collected several samples of Xi'an rainfall typical urban trunk roads throughout the year in 2013 and used inductively coupled plasma mass spectrometry (ICP-MS) to determine the level of Fe, Mn, Pb, Zn, Al, Cd of the samples, then, analyzed the seasonal change of heavy mental. Studies have shown that: the heavy metal of Xi'an road runoff pollutes seriously, the concentration of Fe over three times of the national standard and maintain the higher levels throughout the year, meanwhile the concentration with the intensity of human activities increases. The concentration of Mn and Zn in one year show a trends: winter > autumn > summer> spring. Pb concentration increases with the increase in traffic volume, while showing: winter > spring > summer > autumn. Factor analysis shows: Fe and Al was affected by the same sources-natural sources; Zn, Cd affected by anthropogenic sources of large; Mn, Pb affected by the larger traffic sources.

25 CFR 36.31 - Standard XI-Student promotion requirements.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 25 Indians 1 2014-04-01 2014-04-01 false Standard XI-Student promotion requirements. 36.31 Section 36.31 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR EDUCATION MINIMUM ACADEMIC... programs, in a minimum of 160 instructional days per academic term or 80 instructional days per semester...

25 CFR 36.31 - Standard XI-Student promotion requirements.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 25 Indians 1 2013-04-01 2013-04-01 false Standard XI-Student promotion requirements. 36.31 Section 36.31 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR EDUCATION MINIMUM ACADEMIC... programs, in a minimum of 160 instructional days per academic term or 80 instructional days per semester...

Research on Xi Jinping's Thought of Ecological Civilization and Environment Sustainable Development

NASA Astrophysics Data System (ADS)

Xiang-chao, Pan

2018-05-01

Since the reform and opening up, China’s sustained and rapid economic development, but the environment problem increasingly is prominent in our country. It has seriously affected the sustainability of economic development in China. Environment overall situation is not optimistic, and environmental management is imperative. Since the 18th national congress of the Communist Party of China (CPC), Xi Jin-ping has put forward the thought of building a beautiful China with ecological civilization and realizing the sustainable development of economic construction and environmental protection. Sticking to Xi's Thought of Ecological Civilization is a fundamental guarantee for the sustainable development of environment and building a new era of ecological civilization.

Transoral robotic surgery for the base of tongue squamous cell carcinoma: a preliminary comparison between da Vinci Xi and Si.

PubMed

Alessandrini, Marco; Pavone, Isabella; Micarelli, Alessandro; Caporale, Claudio

2017-09-13

Considering the emerging advantages related to da Vinci Xi robotic platform, the aim of this study is to compare for the first time the operative outcomes of this tool to the previous da Vinci Si during transoral robotic surgery (TORS), both performed for squamous cell carcinomas (SCC) of the base of tongue (BOT). Intra- and peri-operative outcomes of eight patients with early stage (T1-T2) of the BOT carcinoma and undergoing TORS by means of the da Vinci Xi robotic platform (Xi-TORS) are compared with the da Vinci Si group ones (Si-TORS). With respect to Si-TORS group, Xi-TORS group demonstrated a significantly shorter overall operative time, console time, and intraoperative blood loss, as well as peri-operative pain intensity and length of mean hospital stays and nasogastric tube positioning. Considering recent advantages offered by surgical robotic techniques, the da Vinci Xi Surgical System preliminary outcomes could suggest its possible future routine implementation in BOT squamous cell carcinoma procedures.

40 CFR Appendix Xi to Part 86 - Sampling Plans for Selective Enforcement Auditing of Light-Duty Vehicles

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Sampling Plans for Selective Enforcement Auditing of Light-Duty Vehicles XI Appendix XI to Part 86 Protection of Environment ENVIRONMENTAL... Enforcement Auditing of Light-Duty Vehicles 40% AQL Table 1—Sampling Plan Code Letter Annual sales of...

25 CFR 36.31 - Standard XI-Student promotion requirements.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 1 2010-04-01 2010-04-01 false Standard XI-Student promotion requirements. 36.31 Section... Instructional Evaluation § 36.31 Standard XI—Student promotion requirements. Each school shall establish and implement a promotion policy which shall be submitted to and approved by the local school board and Agency...

Does transition from the da Vinci Si to Xi robotic platform impact single-docking technique for robot-assisted laparoscopic nephroureterectomy?

PubMed

Patel, Manish N; Aboumohamed, Ahmed; Hemal, Ashok

2015-12-01

To describe our robot-assisted nephroureterectomy (RNU) technique for benign indications and RNU with en bloc excision of bladder cuff (BCE) and lymphadenectomy (LND) for malignant indications using the da Vinci Si and da Vinci Xi robotic platform, with its pros and cons. The port placement described for Si can be used for standard and S robotic systems. This is the first report in the literature on the use of the da Vinci Xi robotic platform for RNU. After a substantial experience of RNU using different da Vinci robots from the standard to the Si platform in a single-docking fashion for benign and malignant conditions, we started using the newly released da Vinci Xi robot since 2014. The most important differences are in port placement and effective use of the features of da Vinci Xi robot while performing simultaneous upper and lower tract surgery. Patient positioning, port placement, step-by-step technique of single docking RNU-LND-BCE using the da Vinci Si and da Vinci Xi robot are shown in an accompanying video with the goal that centres using either robotic system benefit from the hints and tips. The first segment of video describes RNU-LND-BCE using the da Vinci Si followed by the da Vinci Xi to highlight differences. There was no need for patient repositioning or robot re-docking with the new da Vinci Xi robotic platform. We have experience of using different robotic systems for single docking RNU in 70 cases for benign (15) and malignant (55) conditions. The da Vinci Xi robotic platform helps operating room personnel in its easy movement, allows easier patient side-docking with the help of its boom feature, in addition to easy and swift movements of the robotic arms. The patient clearance feature can be used to avoid collision with the robotic arms or the patient's body. In patients with challenging body habitus and in situations where bladder cuff management is difficult, modifications can be made through reassigning the camera to a different port with

Phase Transition Effects on the Dynamical Stability of Hybrid Neutron Stars

NASA Astrophysics Data System (ADS)

Pereira, Jonas P.; Flores, César V.; Lugones, Germán

2018-06-01

We study radial oscillations of hybrid nonrotating neutron stars composed by a quark matter core and hadronic external layers. At first, we physically deduce the junction conditions that should be imposed between the two phases in these systems when perturbations take place. Then we compute the oscillation spectrum focusing on the effects of slow and rapid phase transitions at the quark-hadron interface. We use a generic MIT-bag model for quark matter and a relativistic mean field theory for hadronic matter. In the case of rapid transitions at the interface, we find a general relativistic version of the reaction mode that has similar properties as its classical counterpart. We also show that the usual static stability condition ∂M/∂ρ c ≥ 0, where ρ c is the central density of a star whose total mass is M, always remains true for rapid transitions but breaks down in general for slow transitions. In fact, for slow transitions, we find that the frequency of the fundamental mode can be a real number (indicating stability) even for some branches of stellar models that verify ∂M/∂ρ c ≤ 0. Thus, when secular instabilities are suppressed, as expected below some critical stellar rotation rate, the existance of twin or even triplet stars with the same gravitational mass but different radii, with one of the counterparts having ∂M/∂ρ c ≤ 0, would be possible. We explore some astrophysical consequences of these results.

Robotic resections in hepatobiliary oncology - initial experience with Xi da Vinci system in India.

PubMed

Chandarana, M; Patkar, S; Tamhankar, A; Garg, S; Bhandare, M; Goel, M

2017-01-01

Minimal invasive surgery has proven its advantages over open surgeries in the perioperative period. Food and Drug Administration approved da Vinci robot in 2000. The latest version, da Vinci Xi system has a mobile tower-based robot with several modifications to improve the functionality, versatility, and operative ease. None of the centers have reported exclusively on hepatobiliary oncology using the da Vinci Xi system. We report our initial experience. To study the feasibility, advantages, and discuss the operative technique of da Vinci Xi system in hepatobiliary oncology. Data were analyzed retrospectively from a prospectively maintained database from June 2015 to October 2016. Twenty-five patients with suspected or proven hepatobiliary malignancies were operated. Total robotic technique using da Vinci Xi system was used. Demographic details and perioperative outcomes were noted. Of the 25 surgeries, 14 patients had a suspected gallbladder malignancy, 11 patients had primary or metastatic liver tumor. Median age was 53 years. The average duration of surgery was 225 min with a median blood loss 150 ml. The median postoperative stay was 4 days. The median nodal yield for radical cholecystectomy was seven. Five patients required conversion. Two of these developed postoperative morbidity. Robotic surgery for hepatobiliary oncology is feasible and can be performed safely in experienced hands. Increasing experience in this field may equal or even prove advantageous over conventional or laparoscopic approach in future. A cautious approach with judicious patient selection is the key to establishing robotic surgery as a standard surgical approach.

Model for End-stage Liver Disease excluding INR (MELD-XI) score in critically ill patients: Easily available and of prognostic relevance.

PubMed

Wernly, Bernhard; Lichtenauer, Michael; Franz, Marcus; Kabisch, Bjoern; Muessig, Johanna; Masyuk, Maryna; Hoppe, Uta C; Kelm, Malte; Jung, Christian

2017-01-01

MELD-XI, an adapted version of Model for End-stage Liver Disease (MELD) score excluding INR, was reported to predict outcomes e.g. in patients with acute heart failure. We aimed to evaluate MELD-XI in critically ill patients admitted to an intensive care unit (ICU) for prognostic relevance. A total of 4381 medical patients (66±14 years, 2862 male) admitted to a German ICU between 2004 and 2009 were included and retrospectively investigated. Admission diagnoses were e.g. myocardial infarction (n = 2034), sepsis (n = 694) and heart failure (n = 688). We divided our patients in two cohorts basing on their MELD-XI score and evaluated the MELD-XI score for its prognostic relevance regarding short-term and long-term survival. Optimal cut-offs were calculated by means of the Youden-Index. Patients with a MELD-XI score >12 had pronounced laboratory signs of organ failure and more comorbidities. MELD-XI >12 was associated with an increase in short-term (27% vs 6%; HR 4.82, 95%CI 3.93-5.93; p<0.001) and long-term (HR 3.69, 95%CI 3.20-4.25; p<0.001) mortality. In a univariate Cox regression analysis for all patients MELD-XI was associated with increased long-term mortality (changes per score point: HR 1.06, 95%CI 1.05-1.07; p<0.001) and remained to be associated with increased mortality after correction in a multivariate regression analysis for renal failure, liver failure, lactate concentration, blood glucose concentration, oxygenation and white blood count (HR 1.04, 95%CI 1.03-1.06; p<0.001). Optimal cut-off for the overall cohort was 11 and varied remarkably depending on the admission diagnosis: myocardial infarction (9), pulmonary embolism (9), cardiopulmonary resuscitation (17) and pneumonia (17). We performed ROC-analysis and compared the AUC: SAPS2 (0.78, 95%CI 0.76-0.80; p<0.0001) and APACHE (0.76, 95%CI 0.74-0.78; p<0.003) score were superior to MELD-XI (0.71, 95%CI 0.68-0.73) for prediction of mortality. The easily calculable MELD-XI score is a robust and reliable

Neutron capture reactions in astrophysics

NASA Astrophysics Data System (ADS)

Käppeler, F.

1985-01-01

About 2/3 of the chemical elements in nature were formed in neutron capture reactions. During the life of a star there are certain evolutionary stages where neutrons are available to build up the elements beyond iron which cannot be synthesized by charged particle reactions. The observed abundance pattern allows to distinguish a rapid and a slow neutron capture process (r- and s-process). The r-process taking place far from the valley of stability is difficult to investigate because of the required extrapolation of nuclear properties to extreme neutron rich nuclei. The s-process, on the other hand, proceeds along the valley of stability. Therefore, the involved isotopes are accessible to laboratory measurements. This information allows for quantitative calculation of s-process abundances and other parameters which represent constraints for stellar models. Two examples are outlined: (i) the s-process branching at A=147, 148 yields a rather accurate value for the neutron density. (ii) Comparison of s-process abundances with observations of stellar atmospheres are particularly interesting for the unstable isotopes 93Zr, 99Tc and 147Pm. Their deficiency with respect to stable neighbors may yield estimates for the transport time from the stellar interior to the surface.

Regulation of organ straightening and plant posture by an actin-myosin XI cytoskeleton.

PubMed

Okamoto, Keishi; Ueda, Haruko; Shimada, Tomoo; Tamura, Kentaro; Kato, Takehide; Tasaka, Masao; Morita, Miyo Terao; Hara-Nishimura, Ikuko

2015-03-23

Plants are able to bend nearly every organ in response to environmental stimuli such as gravity and light(1,2). After this first phase, the responses to stimuli are restrained by an independent mechanism, or even reversed, so that the organ will stop bending and attain its desired posture. This phenomenon of organ straightening has been called autotropism(3) and autostraightening(4) and modelled as proprioception(5). However, the machinery that drives organ straightening and where it occurs are mostly unknown. Here, we show that the straightening of inflorescence stems is regulated by an actin-myosin XI cytoskeleton in specialized immature fibre cells that are parallel to the stem and encircle it in a thin band. Arabidopsis mutants defective in myosin XI (specifically XIf and XIk) or ACTIN8 exhibit hyperbending of stems in response to gravity, an effect independent of the physical properties of the shoots. The actin-myosin XI cytoskeleton enables organs to attain their new position more rapidly than would an oscillating series of diminishing overshoots in environmental stimuli. We propose that the long actin filaments in elongating fibre cells act as a bending tensile sensor to perceive the organ's posture and trigger the straightening system.

A T8.5 BROWN DWARF MEMBER OF THE {xi} URSAE MAJORIS SYSTEM

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

Wright, Edward L.; Mace, Gregory; McLean, Ian S.

The Wide-field Infrared Survey Explorer has revealed a T8.5 brown dwarf (WISE J111838.70+312537.9) that exhibits common proper motion with a solar-neighborhood (8 pc) quadruple star system-{xi} Ursae Majoris. The angular separation is 8.'5, and the projected physical separation is Almost-Equal-To 4000 AU. The sub-solar metallicity and low chromospheric activity of {xi} UMa A argue that the system has an age of at least 2 Gyr. The infrared luminosity and color of the brown dwarf suggests the mass of this companion ranges between 14 and 38 M{sub J} for system ages of 2 and 8 Gyr, respectively.

Use of the new da Vinci Xi® during robotic rectal resection for cancer: a pilot matched-case comparison with the da Vinci Si®.

PubMed

Morelli, Luca; Guadagni, Simone; Di Franco, Gregorio; Palmeri, Matteo; Caprili, Giovanni; D'Isidoro, Cristiano; Cobuccio, Luigi; Marciano, Emanuele; Di Candio, Giulio; Mosca, Franco

2017-03-01

The aim of this study was to compare the short-term outcomes of robotic rectal resection with total mesorectal excision (TME) for rectal cancer, with the use of the new da Vinci Xi® (Xi-RobTME group) and the da Vinci Si® (Si-RobTME group). Ten patients with histologically confirmed rectal cancer underwent robot-assisted TME with the use of the new da Vinci Xi. The outcomes of Xi-RobTME group were compared with a Si-RobTME group selected using a case-matched methodology. Overall operative times and mean hospital stays were shorter in the Xi-RobTME group. Surgeries were fully robotic with a complete take-down of the splenic flexure in all Xi-RobTME cases, while only four cases of the Si-RobTME group were fully robotic, with two cases of complete take-down of the splenic flexure. The new da Vinci Xi could offer some advantages with respect to the da Vinci Si in rectal resection for cancer. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Model for End-stage Liver Disease excluding INR (MELD-XI) score in critically ill patients: Easily available and of prognostic relevance

PubMed Central

Wernly, Bernhard; Lichtenauer, Michael; Franz, Marcus; Kabisch, Bjoern; Muessig, Johanna; Masyuk, Maryna; Hoppe, Uta C.; Kelm, Malte; Jung, Christian

2017-01-01

Purpose MELD-XI, an adapted version of Model for End-stage Liver Disease (MELD) score excluding INR, was reported to predict outcomes e.g. in patients with acute heart failure. We aimed to evaluate MELD-XI in critically ill patients admitted to an intensive care unit (ICU) for prognostic relevance. Methods A total of 4381 medical patients (66±14 years, 2862 male) admitted to a German ICU between 2004 and 2009 were included and retrospectively investigated. Admission diagnoses were e.g. myocardial infarction (n = 2034), sepsis (n = 694) and heart failure (n = 688). We divided our patients in two cohorts basing on their MELD-XI score and evaluated the MELD-XI score for its prognostic relevance regarding short-term and long-term survival. Optimal cut-offs were calculated by means of the Youden-Index. Results Patients with a MELD-XI score >12 had pronounced laboratory signs of organ failure and more comorbidities. MELD-XI >12 was associated with an increase in short-term (27% vs 6%; HR 4.82, 95%CI 3.93–5.93; p<0.001) and long-term (HR 3.69, 95%CI 3.20–4.25; p<0.001) mortality. In a univariate Cox regression analysis for all patients MELD-XI was associated with increased long-term mortality (changes per score point: HR 1.06, 95%CI 1.05–1.07; p<0.001) and remained to be associated with increased mortality after correction in a multivariate regression analysis for renal failure, liver failure, lactate concentration, blood glucose concentration, oxygenation and white blood count (HR 1.04, 95%CI 1.03–1.06; p<0.001). Optimal cut-off for the overall cohort was 11 and varied remarkably depending on the admission diagnosis: myocardial infarction (9), pulmonary embolism (9), cardiopulmonary resuscitation (17) and pneumonia (17). We performed ROC-analysis and compared the AUC: SAPS2 (0.78, 95%CI 0.76–0.80; p<0.0001) and APACHE (0.76, 95%CI 0.74–0.78; p<0.003) score were superior to MELD-XI (0.71, 95%CI 0.68–0.73) for prediction of mortality. Conclusions The easily

Chondrogenic properties of collagen type XI, a component of cartilage extracellular matrix.

PubMed

Li, Ang; Wei, Yiyong; Hung, Clark; Vunjak-Novakovic, Gordana

2018-08-01

Cartilage extracellular matrix (ECM) has been used for promoting tissue engineering. However, the exact effects of ECM on chondrogenesis and the acting mechanisms are not well understood. In this study, we investigated the chondrogenic effects of cartilage ECM on human mesenchymal stem cells (MSCs) and identified the contributing molecular components. To this end, a preparation of articular cartilage ECM was supplemented to pellets of chondrogenically differentiating MSCs, pellets of human chondrocytes, and bovine articular cartilage explants to evaluate the effects on cell proliferation and the production of cartilaginous matrix. Selective enzymatic digestion and screening of ECM components were conducted to identify matrix molecules with chondrogenic properties. Cartilage ECM promoted MSC proliferation, production of cartilaginous matrix, and maturity of chondrogenic differentiation, and inhibited the hypertrophic differentiation of MSC-derived chondrocytes. Selective digestion of ECM components revealed a contributory role of collagens in promoting chondrogenesis. The screening of various collagen subtypes revealed strong chondrogenic effect of collagen type XI. Finally, collagen XI was found to promote production and inhibit degradation of cartilage matrix in human articular chondrocyte pellets and bovine articular cartilage explants. Our results indicate that cartilage ECM promotes chondrogenesis and inhibits hypertrophic differentiation in MSCs. Collagen type XI is the ECM component that has the strongest effects on enhancing the production and inhibiting the degradation of cartilage matrix. Copyright © 2018 Elsevier Ltd. All rights reserved.

Infrared studies of defects formed during postirradiation anneals of Czochralski silicon

NASA Astrophysics Data System (ADS)

Londos, C. A.; Sarlis, N. V.; Fytros, L. G.

1998-10-01

This article reports on defect studies of neutron-irradiated Czochralski-grown silicon (Cz-Si) material by means of infrared spectroscopy. In particular, the investigation was focused on the evolution of the 828 cm-1 well-known band of A-center, due to isochronal anneals from room temperature (RT) up to ≈700 °C. The strength of the VO band begins to increase above ≈200 gradually up to 300 °C (stage I); then, it begins to decrease up to ≈400 °C (stage II), where upon it stabilizes up to ≈550 °C (stage III). Upon re-irradiation under exactly the same conditions and repeating the annealing process, the increase of the VO signal in stage I disappears. The phenomenon is ascribed to the existence of defect aggregates labeled as Xi centers which are correlated with (impurity-defect) clusters that compete with Oi in capturing vacancies. The presence of Xi centers is related to the thermal annealings performed. Comparison of the evolution of VO (828 cm-1) and VO2 (887 cm-1) bands between irradiated and re-irradiated materials, during stage II, is made and the results are discussed in the framework of established reaction patterns. The stabilization of the amplitude of the 828 cm-1 line in stage III is examined. The prevailing aspect is that a portion of A-centers in neutron-irradiated Si acquires larger thermal stability by relaxing in the vicinity of larger defects.

BRCA1 does not paint the inactive X to localize XIST RNA but may contribute to broad changes in cancer that impact XIST and Xi heterochromatin.

PubMed

Pageau, Gayle J; Hall, Lisa L; Lawrence, Jeanne B

2007-03-01

The BRCA1 tumor suppressor involved in breast and ovarian cancer is linked to several fundamental cell regulatory processes. Recently, it was reported that BRCA1 supports localization of XIST RNA to the inactive X chromosome (Xi) in women. The apparent cytological overlap between BRCA1 and XIST RNA across the Xi raised the possibility a direct role of BRCA1 in localizing XIST. We report here that BRCA1 does not paint the Xi or XIST territory, as do markers of Xi facultative heterochromatin. A smaller BRCA1 accumulation abuts Xi, although this is not exclusive to Xi. In BRCA1 depleted normal and tumor cells, or BRCA1 reconstituted cells, BRCA1 status does not closely correlate with XIST localization, however in a BRCA1 inducible system over-expression correlated strongly with enhanced XIST expression. We confirm frequent loss of an Xi in tumor cells. In addition to mitotic loss of Xi, we find XIST RNA expression or localization frequently become compromised in cultured breast cancer cells, suggesting Xi heterochromatin may not be fully maintained. We demonstrate that complex epigenetic differences between tumor cell subpopulations can have striking effects on XIST transcription, accumulation, and localization, but this does not strictly correlate with BRCA1. Although BRCA1 can have indirect effects that impact XIST, our results do not indicate a direct and specific role in XIST RNA regulation. Rather, regulatory factors such as BRCA1 that have broad effects on chromatin or gene regulation can impact XIST RNA and the Xi. We provide preliminary evidence that this may occur as part of a wider failure of heterochromatin maintenance in some cancers.

Coronal Diagnostics of Intermediate Activity Star XI Boo A

NASA Technical Reports Server (NTRS)

Drake, Jeremy

2005-01-01

The analysis of Xi Boo A proved difficult to adapt to our line-by-line approach because of the strong wings of the RGS instrumental profile, as has been detailed in earlier reports. While progress was also delayed because of problems in using SAS v4, we succeeded in the past year or so to bring the analysis to conclusion. Abundances have been derived using both EPIC and RGS data, confirming earlier EUVE findings of a mild solar-like FIP effect, though with some evidence of a turn-up in abundances of elements with higher FIP. Plasma densities appear normal for a moderately active stellar corona. Xi Boo A nicely bridges the gap between the very active stars and stars like the Sun, and it indeed does appear that these are the stars in which the solar-like FIP effects begins to change to the "inverse FIP" type of effect seen in the very active stars. Probing this divide was the main goal of the proposal. These results are in the process of being prepared for publication, though we have not decided the target journal as yet.

Source contributions of fine particulate matter during one winter haze episodes in Xi'an, China

NASA Astrophysics Data System (ADS)

Yang, X.; Wu, Q.

2017-12-01

Long-term exposure to high levels of fine particulate matter (PM2.5) is found to be associated with adverse effects on human health, ecological environment and climate change. Identification the major source regions of fine particulate matter are essential to proposing proper joint prevention and control strategies for heavy haze mitigation. In this work, the Comprehensive Air Quality Model with extensions (CAMx) together with the Particulate Source Apportionment Technology (PSAT) and the Weather Research and Forecast Model (WRF), have been applied to analyze the major source regions of PM2.5 in Xi'an during the heavy haze episodes in winter (29, December, 2016 - 5 January 2017), and the framework of the model system is shown in Fig. 1. Firstly, according to the model evaluation of the daily PM2.5 concentrations for the two months, the model has well performance, and the fraction of predictions within a factor of 2 of the observations (FAC2) is 84%, while the correlation coefficient (R) is 0.80 in Xi'an. By using the PSAT in CAMx model, a detailed source region contribution matrix is derived for all points within the Xi'an region and its six surrounding areas, and long-range regional transport. The results show that the local emission in Xi'an is the mainly sources at downtown area, which contributing 72.9% as shown in Fig.2, and the contribution rate of transportations between adjacent areas depends on wind direction. Meanwhile, three different suburban areas selected for detailed analysis in fine particles sources. Comparing to downtown area, the sources of suburban areas are more multiply, and the transportations make the contribution 40%-82%. In the suburban areas, regional inflows play an important role in the fine particles concentrations, indicating a strong need for regional joint emission control efforts. The results enhance the quantitative understanding of the PM2.5 source regions and provide a basis for policymaking to advance the control of pollution

Gravitational wave content and stability of uniformly, rotating, triaxial neutron stars in general relativity.

PubMed

Tsokaros, Antonios; Ruiz, Milton; Paschalidis, Vasileios; Shapiro, Stuart L; Baiotti, Luca; Uryū, Kōji

2017-06-15

Targets for ground-based gravitational wave interferometers include continuous, quasiperiodic sources of gravitational radiation, such as isolated, spinning neutron stars. In this work, we perform evolution simulations of uniformly rotating, triaxially deformed stars, the compressible analogs in general relativity of incompressible, Newtonian Jacobi ellipsoids. We investigate their stability and gravitational wave emission. We employ five models, both normal and supramassive, and track their evolution with different grid setups and resolutions, as well as with two different evolution codes. We find that all models are dynamically stable and produce a strain that is approximately one-tenth the average value of a merging binary system. We track their secular evolution and find that all our stars evolve toward axisymmetry, maintaining their uniform rotation, rotational kinetic energy, and angular momentum profiles while losing their triaxiality.

Detection of mecC-Positive Staphylococcus aureus (CC130-MRSA-XI) in Diseased European Hedgehogs (Erinaceus europaeus) in Sweden

PubMed Central

Monecke, Stefan; Gavier-Widen, Dolores; Mattsson, Roland; Rangstrup-Christensen, Lena; Lazaris, Alexandros; Coleman, David C.; Shore, Anna C.; Ehricht, Ralf

2013-01-01

Recently, a novel mec gene conferring beta-lactam resistance in Staphylococcus aureus has been discovered. This gene, mecC, is situated on a SCCmec XI element that has to date been identified in clonal complexes 49, 130, 425, 599 and 1943. Some of the currently known isolates have been identified from animals. This, and observations of mecA alleles that do not confer beta-lactam resistance, indicate that mec genes might have a reservoir in Staphylococcus species from animals. Thus it is important also to screen wildlife isolates for mec genes. Here, we describe mecC-positive Staphylococcus aureus (ST130-MRSA-XI) and the lesions related to the infection in two diseased free-ranging European hedgehogs (Erinaceus europaeus). One was found dead in 2003 in central Sweden, and suffered from S. aureus septicaemia. The other one, found on the island of Gotland in the Baltic Sea in 2011, showed a severe dermatitis and was euthanised. ST130-MRSA-XI isolates were isolated from lesions from both hedgehogs and were essentially identical to previously described isolates from humans. Both isolates carried the complete SCCmec XI element. They lacked the lukF-PV/lukS-PV and lukM/lukF-P83 genes, but harboured a gene for an exfoliative toxin homologue previously described from Staphylococcus hyicus, Staphylococcus pseudintermedius and other S. aureus of the CC130 lineage. To the best of our knowledge, these are the first reported cases of CC130-MRSA-XI in hedgehogs. Given that one of the samples was taken as early as 2003, this was the earliest detection of this strain and of mecC in Sweden. This and several other recent observations suggest that CC130 might be a zoonotic lineage of S. aureus and that SCCmec XI/mecC may have originated from animal pathogens. PMID:23776626

Detection of mecC-positive Staphylococcus aureus (CC130-MRSA-XI) in diseased European hedgehogs (Erinaceus europaeus) in Sweden.

PubMed

Monecke, Stefan; Gavier-Widen, Dolores; Mattsson, Roland; Rangstrup-Christensen, Lena; Lazaris, Alexandros; Coleman, David C; Shore, Anna C; Ehricht, Ralf

2013-01-01

Recently, a novel mec gene conferring beta-lactam resistance in Staphylococcus aureus has been discovered. This gene, mecC, is situated on a SCCmec XI element that has to date been identified in clonal complexes 49, 130, 425, 599 and 1943. Some of the currently known isolates have been identified from animals. This, and observations of mecA alleles that do not confer beta-lactam resistance, indicate that mec genes might have a reservoir in Staphylococcus species from animals. Thus it is important also to screen wildlife isolates for mec genes. Here, we describe mecC-positive Staphylococcus aureus (ST130-MRSA-XI) and the lesions related to the infection in two diseased free-ranging European hedgehogs (Erinaceus europaeus). One was found dead in 2003 in central Sweden, and suffered from S. aureus septicaemia. The other one, found on the island of Gotland in the Baltic Sea in 2011, showed a severe dermatitis and was euthanised. ST130-MRSA-XI isolates were isolated from lesions from both hedgehogs and were essentially identical to previously described isolates from humans. Both isolates carried the complete SCCmec XI element. They lacked the lukF-PV/lukS-PV and lukM/lukF-P83 genes, but harboured a gene for an exfoliative toxin homologue previously described from Staphylococcus hyicus, Staphylococcus pseudintermedius and other S. aureus of the CC130 lineage. To the best of our knowledge, these are the first reported cases of CC130-MRSA-XI in hedgehogs. Given that one of the samples was taken as early as 2003, this was the earliest detection of this strain and of mecC in Sweden. This and several other recent observations suggest that CC130 might be a zoonotic lineage of S. aureus and that SCCmec XI/mecC may have originated from animal pathogens.

[Correlativity study of the distribution of soil magnetic susceptibility and the heavy metal contents in Xi'an City].

PubMed

Chen, Xiu-Duan; Lu, Xin-Wei; Yang, Guang

2013-03-01

The magnetic susceptibility and the concentrations of Co, Cr, Cu, Pb, Sn, Sr and Ba in topsoil samples from Xi'an City were measured to study their spatial distribution and their correlation in this study. The results show that the concentrations of all measured heavy metals are higher than their background values in Cinnamon topsoil, which is the main soil type of Xi'an City. The heavy metals concentrations and the magnetic susceptibility of the studied samples display moderate variance. Co, Cr, Cu, Pb, Sn, Sr and Ba are significantly positively correlated with low-frequency magnetic susceptibility, while are significantly negatively correlated with frequency susceptibility. The spatial distribution of low-frequency magnetic susceptibility is identical with the concentrations of Pb and Cu. However, the spatial variation of frequency magnetic susceptibility is different from the concentrations of Co, Cr and Ba. The pollution assessment results show that the heavy metal pollution in topsoil of Xi'an City is moderate. The spatial contribution of the pollution load index was significantly correlated with the magnetic susceptibility of topsoil in Xi'an City. Therefore, soil magnetic susceptibility can be used as an effective monitoring means for heavy metal pollution in urban soil.

Insight into the da Vinci® Xi - technical notes for single-docking left-sided colorectal procedures.

PubMed

Ngu, James Chi-Yong; Sim, Sarah; Yusof, Sulaiman; Ng, Chee-Yung; Wong, Andrew Siang-Yih

2017-12-01

The adoption of robot-assisted laparoscopic colorectal surgery has been hampered by issues with docking, operative duration, technical difficulties in multi-quadrant access, and cost. The da Vinci® Xi has been designed to overcome some of these limitations. We describe our experience with the system and offer technical insights to its application in left-sided colorectal procedures. Our initial series of left-sided robotic colorectal procedures was evaluated. Patient demographics and operative outcomes were recorded prospectively using a predefined database. Between March 2015 and April 2016, 54 cases of robot-assisted laparoscopic left-sided colorectal procedures were successfully completed with no cases of conversion. The majority were low anterior resections for colorectal malignancies. Using the da Vinci® Xi Surgical System, multi-quadrant surgery involving dissection from the splenic flexure to the pelvis was possible without redocking. The da Vinci® Xi simplifies the docking procedure and makes single-docking feasible for multi-quadrant left-sided colorectal procedures. Copyright © 2016 John Wiley & Sons, Ltd.

Neutron stars structure in the context of massive gravity

NASA Astrophysics Data System (ADS)

Hendi, S. H.; Bordbar, G. H.; Eslam Panah, B.; Panahiyan, S.

2017-07-01

Motivated by the recent interests in spin-2 massive gravitons, we study the structure of neutron star in the context of massive gravity. The modifications of TOV equation in the presence of massive gravity are explored in 4 and higher dimensions. Next, by considering the modern equation of state for the neutron star matter (which is extracted by the lowest order constrained variational (LOCV) method with the AV18 potential), different physical properties of the neutron star (such as Le Chatelier's principle, stability and energy conditions) are investigated. It is shown that consideration of the massive gravity has specific contributions into the structure of neutron star and introduces new prescriptions for the massive astrophysical objects. The mass-radius relation is examined and the effects of massive gravity on the Schwarzschild radius, average density, compactness, gravitational redshift and dynamical stability are studied. Finally, a relation between mass and radius of neutron star versus the Planck mass is extracted.

Transoral robotic thyroidectomy: a preclinical feasibility study using the da Vinci Xi platform.

PubMed

Russell, Jonathon O; Noureldine, Salem I; Al Khadem, Mai G; Chaudhary, Hamad A; Day, Andrew T; Kim, Hoon Yub; Tufano, Ralph P; Richmon, Jeremy D

2017-09-01

Transoral thyroid surgery allows the surgeon to conceal incisions within the oral cavity without significantly increasing the amount of required dissection. TORT provides an ideal scarless, midline access to the thyroid gland and bilateral central neck compartments. This approach, however, presents multiple technical challenges. Herein, we present our experience using the latest generation robotic surgical system to accomplish transoral robotic thyroidectomy (TORT). In two human cadavers, the da Vinci Xi surgical system (Intuitive Surgical, Sunnyvale, CA, USA) was used to complete TORT. Total thyroidectomy and bilateral central neck dissection was successfully completed in both cadavers. The da Vinci Xi platform offered several technologic advantages over previous robotic generations including overhead docking, narrower arms, and improved range of motion allowing for improved execution of previously described TORT techniques.

Multiwavelength observations of magnetic fields and related activity on XI Bootis A

NASA Technical Reports Server (NTRS)

Saar, Steven H.; Huovelin, J.; Linsky, Jeffrey L.; Giampapa, Mark S.; Jordan, Carole

1988-01-01

Preliminary results of coordinated observations of magnetic fields and related activity on the active dwarf, Xi Boo A, are presented. Combining the magnetic fluxes with the linear polarization data, a simple map of the stellar active regions is constructed.

2 CFR 376.147 - Does an exclusion from participation in Federal health care programs under Title XI of the Social...

Code of Federal Regulations, 2010 CFR

2010-01-01

... Federal health care programs under Title XI of the Social Security Act affect a person's eligibility to..., Medicaid, and other Federal health care programs under Title XI of the Social Security Act, 42 U.S.C. 1320a... Federal Agency Regulations for Grants and Agreements DEPARTMENT OF HEALTH AND HUMAN SERVICES...

A neutron scattering study on the stability of trehalose mycolates under thermal stress

NASA Astrophysics Data System (ADS)

Migliardo, F.; Salmeron, C.; Bayan, N.

2013-10-01

The present paper is focused on the study of the dynamics of mycolic acids, which are fundamental components of the outer membrane (mycomembrane) of Mycobacterium tuberculosis. An elastic neutron scattering study of mycolic acid/H2O and lecithin/H2O mixtures as a function of temperature and exchanged wavevector Q has been carried out. This study provides an effective way for characterizing the dynamical properties, furnishing a set of parameters characterizing the different flexibility and rigidity of the investigated lipids. The behavior of the elastically scattered intensity profiles and the derived mean square displacements as a function of temperature shows a more marked temperature dependence for lecithin lipids in comparison with mycolic acids, so revealing a higher thermal stability of these latter. These findings could be useful for understanding the dynamics-function relation in the mycomembrane and then to relate it to the low permeability and high resistance of mycobacteria to many antibiotics.

Neutron-induced fission: properties of prompt neutron and γ rays as a function of incident energy

NASA Astrophysics Data System (ADS)

Stetcu, I.; Talou, P.; Kawano, T.

2016-06-01

We have applied the Hauser-Feshbach statistical theory, in a Monte-Carlo implementation, to the de-excitation of fission fragments, obtaining a reasonable description of the characteristics of neutrons and gamma rays emitted before beta decays toward stability. Originally implemented for the spontaneous fission of 252Cf and the neutroninduced fission of 235U and 239Pu at thermal neutron energy, in this contribution we discuss the extension of the formalism to incident neutron energies up to 20 MeV. For the emission of pre-fission neutrons, at incident energies beyond second-chance fission, we take into account both the pre-equilibrium and statistical pre-fission components. Phenomenological parameterizations of mass, charge and TKE yields are used to obtain the initial conditions for the fission fragments that subsequently decay via neutron and emissions. We illustrate this approach for 239Pu(n,f).

Boron selenide semiconductor detectors for thermal neutron counting

NASA Astrophysics Data System (ADS)

Kargar, Alireza; Tower, Joshua; Cirignano, Leonard; Shah, Kanai

2013-09-01

Thermal neutron detectors in planar configuration were fabricated from B2Se3 (Boron Selenide) crystals grown at RMD Inc. All fabricated semiconductor devices were characterized for the current-voltage (I-V) characteristic and neutron counting measurement. In this study, the resistivity of crystals is reported and the collected pulse height spectra are presented for devices irradiated with the 241AmBe neutron source. Long-term stability of the B2Se3 devices for neutron detection under continuous bias and without being under continuous bias was investigated and the results are reported. The B2Se3 devices showed response to thermal neutrons of the 241AmBe source.

Dynamic stabilization of the magnetic field surrounding the neutron electric dipole moment spectrometer at the Paul Scherrer Institute

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

Afach, S.; Fertl, M.; Franke, B., E-mail: beatrice.franke@psi.ch, E-mail: bernhard.lauss@psi.ch

The Surrounding Field Compensation (SFC) system described in this work is installed around the four-layer Mu-metal magnetic shield of the neutron electric dipole moment spectrometer located at the Paul Scherrer Institute. The SFC system reduces the DC component of the external magnetic field by a factor of about 20. Within a control volume of approximately 2.5 m × 2.5 m × 3 m, disturbances of the magnetic field are attenuated by factors of 5–50 at a bandwidth from 10{sup −3} Hz up to 0.5 Hz, which corresponds to integration times longer than several hundreds of seconds and represent the important timescale for the neutron electric dipole moment measurement.more » These shielding factors apply to random environmental noise from arbitrary sources. This is achieved via a proportional-integral feedback stabilization system that includes a regularized pseudoinverse matrix of proportionality factors which correlates magnetic field changes at all sensor positions to current changes in the SFC coils.« less

The Pioneer XI high field fluxgate magnetometer

NASA Technical Reports Server (NTRS)

Acuna, M. A.; Ness, N. F.

1975-01-01

The high field fluxgate magnetometer experiment flown aboard the Pioneer XI spacecraft is described. This extremely simple instrument was used to extend the spacecraft's upper-limit measurement capability by approximately an order of magnitude (from 0.14 mT to 1.00 mT) with minimum power and volume requirements. This magnetometer was designed to complement the low-field measurements provided by a helium vector magnetometer and utilizes magnetic ring core sensors with biaxial orthogonal sense coils. The instrument is a single-range, triaxial-fluxgate magnetometer capable of measuring fields of up to 1 mT along each orthogonal axis, with a maximum resolution of 1 microT.

OATYC Journal; Vol. XI, Nos. 1-2, Fall 1985-Spring 1986.

ERIC Educational Resources Information Center

Fullen, James, Ed.

1986-01-01

"OATYC Journal," which is published by the Ohio Association of Two-Year Colleges, is designed as a forum for the exchange of concepts, methods, and findings relevant to the two-year college classroom. Along with commentaries and letters of reaction from the readership, the two issues of volume XI contain the following: (1) "Focus:…

RESOLVING THE {xi} BOO BINARY WITH CHANDRA, AND REVEALING THE SPECTRAL TYPE DEPENDENCE OF THE CORONAL 'FIP EFFECT'

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

Wood, Brian E.; Linsky, Jeffrey L., E-mail: brian.wood@nrl.navy.mi, E-mail: jlinsky@jila.colorado.ed

On 2008 May 2, Chandra observed the X-ray spectrum of {xi} Boo (G8 V+K4 V), resolving the binary for the first time in X-rays and allowing the coronae of the two stars to be studied separately. With the contributions of {xi} Boo A and B to the system's total X-ray emission now observationally established (88.5% and 11.5%, respectively), consideration of mass loss measurements for GK dwarfs of various activity levels (including one for {xi} Boo) leads to the surprising conclusion that {xi} Boo B may dominate the wind from the binary, with {xi} Boo A's wind being very weak despitemore » its active corona. Emission measure (EM) distributions and coronal abundances are computed for both stars and compared with Chandra measurements of other moderately active stars with G8-K5 spectral types, all of which exhibit a narrow peak in EM near log T = 6.6, indicating that the coronal heating process in these stars has a strong preference for this temperature. As is the case for the Sun and many other stars, our sample of stars shows coronal abundance anomalies dependent on the first ionization potential (FIP) of the element. We see no dependence of the degree of 'FIP effect' on activity, but there is a dependence on spectral type, a correlation that becomes more convincing when moderately active main-sequence stars with a broader range of spectral types are considered. This clear dependence of coronal abundances on spectral type weakens if the stellar sample is allowed to be contaminated by evolved stars, interacting binaries, or extremely active stars with log L{sub X} >29, explaining why this correlation has not been recognized in the past.« less

Stabilization of Model Membrane Systems by Disaccharides. Quasielastic Neutron Scattering Experiments and Atomistic Simulations

NASA Astrophysics Data System (ADS)

Doxastakis, Emmanouil; Garcia Sakai, Victoria; Ohtake, Satoshi; Maranas, Janna K.; de Pablo, Juan J.

2006-03-01

Trehalose, a disaccharide of glucose, is often used for the stabilization of cell membranes in the absence of water. This work studies the effects of trehalose on model membrane systems as they undergo a melting transition using a combination of experimental methods and atomistic molecular simulations. Quasielastic neutron scattering experiments on selectively deuterated samples provide the incoherent dynamic structure over a wide time range. Elastic scans probing the lipid tail dynamics display clear evidence of a main melting transition that is significantly lowered in the presence of trehalose. Lipid headgroup mobility is considerably restricted at high temperatures and directly associated with the dynamics of the sugar in the mixture. Molecular simulations provide a detailed overview of the dynamics and their spatial and time dependence. The combined simulation and experimental methodology offers a unique, molecular view of the physics of systems commonly employed in cryopreservation and lyophilization processes.

Structural stability of anhydrous proton conducting SrZr0.9Er0.1O3-δ perovskite ceramic vs. protonation/deprotonation cycling: Neutron diffraction and Raman studies

NASA Astrophysics Data System (ADS)

Slodczyk, Aneta; Colomban, Philippe; Upasen, Settakorn; Grasset, Frédéric; André, Gilles

2015-08-01

Long-term chemical and structural stability of an ion conducting ceramic is one of the main criteria for its selection as an electrolytic membrane in energy plant devices. Consequently, medium density SrZr0.9Er0.1O3-δ (SZE) anhydrous proton conducting ceramic - a potential electrolyte of SOFC/PCFC, was analysed by neutron diffraction between room temperature and 900 °C. After the first heating/cooling cycle, the ceramic pieces were exposed to water vapour pressure in an autoclave (500 °C, 40 bar, 7 days) in order to incorporate protonic species; the protonated compound was then again analysed by neutron diffraction. This procedure was repeated two times. At each step, the sample was also controlled by TGA and Raman spectroscopy. These studies allow the first comprehensive comparison of structural and chemical stability during the protonation/deprotonation cycling. The results reveal good structural stability, although an irreversible small contraction of the unit-cell volume and local structure modifications near Zr/ErO5[] octahedra are detected after the first protonation. After the second protonation easy ceramic crumbling under a stress is observed because of the presence of secondary phases (SrCO3, Sr(OH)2) well detected by Raman scattering and TGA. The role of crystallographic purity, substituting element and residual porosity in the proton conducting perovskite electrolyte stability is discussed.

Shining a light on Jarosite: formation, alteration and stability studies using in situ experimental synchrotron and neutron techniques.

NASA Astrophysics Data System (ADS)

Brand, H. E. A.; Scarlett, N. V. Y.; Wilson, S. A.; Frierdich, A. J.; Grey, I. E.

2016-12-01

Jarosites and related minerals are critical to a range of mineral processing and research applications. They are used in the removal of iron species from smelting processes; they occur in metal bioleaching systems, and they are present in acid mine drainage environments. There has been a recent resurgence in interest in jarosites since their detection on Mars. In this context, the presence of jarosite has been recognised as a likely indicator of liquid water at the surface of Mars in the past & it is thought that their study will provide insight into the environmental history of Mars. Acid sulfate soils cover large areas of the Australian coastline and are likely to be a major constituent of the Martian environment. The oxidation of acid sulfate soils, coupled with potential release of heavy metals and acidic groundwaters, can have serious consequences for fragile ecosystems. Understanding these sediments will provide insight into the biogeochemical processes that affect the lifetimes of transient mineral species on Earth, and may be used to better understand soil acidification, contaminant mobility at sites affected by acid and metalliferous drainage, and even constrain past weathering and putative biosignatures on Mars. Knowledge of the behaviour of jarosite minerals under the actual conditions that they are found in is crucial to understanding their potential environmental impacts on both Earth and Mars. To this end, we are engaged in a program to study the formation, stability and alteration of natural and synthetic jarosite minerals using a complementary suite of in situ synchrotron and neutron techniques. There are 3 sections to this work that will introduce the experimental techniques and sample environments that make these measurements possible: Studying the nucleation and growth of jarosites under laboratory conditions. The experimentation consisted of time-resolved synchrotron small angle X-ray scattering and X-ray diffraction. Studying the stability of

Influence of Problem-Based Learning Model of Learning to the Mathematical Communication Ability of Students of Grade XI IPA SMAN 14 Padang

NASA Astrophysics Data System (ADS)

Nisa, I. M.

2018-04-01

The ability of mathematical communication is one of the goals of learning mathematics expected to be mastered by students. However, reality in the field found that the ability of mathematical communication the students of grade XI IPA SMA Negeri 14 Padang have not developed optimally. This is evident from the low test results of communication skills mathematically done. One of the factors that causes this happens is learning that has not been fully able to facilitate students to develop mathematical communication skills well. By therefore, to improve students' mathematical communication skills required a model in the learning activities. One of the models learning that can be used is Problem Based learning model Learning (PBL). The purpose of this study is to see whether the ability the students' mathematical communication using the PBL model better than the students' mathematical communication skills of the learning using conventional learning in Class XI IPA SMAN 14 Padang. This research type is quasi experiment with design Randomized Group Only Design. Population in this research that is student of class XI IPA SMAN 14 Padang with sample class XI IPA 3 and class XI IPA 4. Data retrieval is done by using communication skill test mathematically shaped essay. To test the hypothesis used U-Mann test Whitney. Based on the results of data analysis, it can be concluded that the ability mathematical communication of students whose learning apply more PBL model better than the students' mathematical communication skills of their learning apply conventional learning in class XI IPA SMA 14 Padang at α = 0.05. This indicates that the PBL learning model effect on students' mathematical communication ability.

Robot-assisted total mesorectal excision for rectal cancer: case-matched comparison of short-term surgical and functional outcomes between the da Vinci Xi and Si.

PubMed

Morelli, Luca; Di Franco, Gregorio; Guadagni, Simone; Rossi, Leonardo; Palmeri, Matteo; Furbetta, Niccolò; Gianardi, Desirée; Bianchini, Matteo; Caprili, Giovanni; D'Isidoro, Cristiano; Mosca, Franco; Moglia, Andrea; Cuschieri, Alfred

2018-02-01

Robotic rectal resection with da Vinci Si has some technical limitations, which could be overcome by the new da Vinci Xi. We compare short-term surgical and functional outcomes following robotic rectal resection with total mesorectal excision for cancer, with the da Vinci Xi (Xi-RobTME group) and the da Vinci Si (Si-RobTME group). The first consecutive 30 Xi-RobTME were compared with a Si-RobTME control group of 30 patients, selected using a one-to-one case-matched methodology from our prospectively collected Institutional database, comprising all cases performed between April 2010 and September 2016 by a single surgeon. Perioperative outcomes were compared. The impact of minimally invasive TME on autonomic function and quality of life was analyzed with specific questionnaires. The docking and overall operative time were shorter in the Xi-RobTME group (p < 0.001 and p < 0.05 respectively). The mean differences of overall operative time and docking time were -33.8 min (95% CI -5.1 to -64.5) and -6 min (95% CI -4.1 to -7.9), respectively. A fully-robotic approach with complete splenic flexure mobilization was used in 30/30 (100%) of the Xi-RobTME cases and in 7/30 (23%) of the Si-RobTME group (p < 0.001). The hybrid approach in males and patients with BMI > 25 kg/m 2 was necessary in ten patients (45 vs. 0%, p < 0.001) and in six patients (37 vs. 0%, p < 0.05), in the Si-RobTME and Xi-RobTME groups, respectively. There were no differences in conversion rate, mean hospital stay, pathological data, and in functional outcomes between the two groups before and at 1 year after surgery. The technical advantages offered by the da Vinci Xi seem to be mainly associated with a shorter docking and operative time and with superior ability to perform a fully-robotic approach. Clinical and functional outcomes seem not to be improved, with the introduction of the new Xi platform.

In-situ neutron diffraction and crystal plasticity finite element modeling to study the kinematic stability of retained austenite in bearing steels

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

Voothaluru, Rohit; Bedekar, Vikram; Xie, Qingge

This work integrates in-situ neutron diffraction and crystal plasticity finite element modeling to study the kinematic stability of retained austenite in high carbon bearing steels. The presence of a kinematically metastable retained austenite in bearing steels can significantly affect the macro-mechanical and micro-mechanical material response. Mechanical characterization of metastable austenite is a critical component in accurately capturing the micro-mechanical behavior under typical application loads. Traditional mechanical characterization techniques are unable to discretely quantify the micro-mechanical response of the austenite, and as a result, the computational predictions rely heavily on trial and error or qualitative descriptions of the austenite phase. Inmore » order to overcome this, in the present work, we use in-situ neutron diffraction of a uniaxial tension test of an A485 Grade 1 bearing steel specimen. The mechanical response determined from the neutron diffraction analysis was incorporated into a hybrid crystal plasticity finite element model that accounts for the martensite's crystal plasticity and the stress-assisted transformation from austenite to martensite in bearing steels. Here, the modeling response was used to estimate the single crystal elastic constants of the austenite and martensite phases. Finally, the results show that using in-situ neutron diffraction, coupled with a crystal plasticity model, can successfully predict both the micro-mechanical and macro-mechanical responses of bearing steels while accounting for the martensitic transformation of the retained austenite.« less

In-situ neutron diffraction and crystal plasticity finite element modeling to study the kinematic stability of retained austenite in bearing steels

DOE PAGES

Voothaluru, Rohit; Bedekar, Vikram; Xie, Qingge; ...

2018-11-21

This work integrates in-situ neutron diffraction and crystal plasticity finite element modeling to study the kinematic stability of retained austenite in high carbon bearing steels. The presence of a kinematically metastable retained austenite in bearing steels can significantly affect the macro-mechanical and micro-mechanical material response. Mechanical characterization of metastable austenite is a critical component in accurately capturing the micro-mechanical behavior under typical application loads. Traditional mechanical characterization techniques are unable to discretely quantify the micro-mechanical response of the austenite, and as a result, the computational predictions rely heavily on trial and error or qualitative descriptions of the austenite phase. Inmore » order to overcome this, in the present work, we use in-situ neutron diffraction of a uniaxial tension test of an A485 Grade 1 bearing steel specimen. The mechanical response determined from the neutron diffraction analysis was incorporated into a hybrid crystal plasticity finite element model that accounts for the martensite's crystal plasticity and the stress-assisted transformation from austenite to martensite in bearing steels. Here, the modeling response was used to estimate the single crystal elastic constants of the austenite and martensite phases. Finally, the results show that using in-situ neutron diffraction, coupled with a crystal plasticity model, can successfully predict both the micro-mechanical and macro-mechanical responses of bearing steels while accounting for the martensitic transformation of the retained austenite.« less

Stabilization of Particle Discrimination Efficiencies for Neutron Spectrum Unfolding With Organic Scintillators

NASA Astrophysics Data System (ADS)

Lawrence, Chris C.; Polack, J. K.; Febbraro, Michael; Kolata, J. J.; Flaska, Marek; Pozzi, S. A.; Becchetti, F. D.

2017-02-01

The literature discussing pulse-shape discrimination (PSD) in organic scintillators dates back several decades. However, little has been written about PSD techniques that are optimized for neutron spectrum unfolding. Variation in n-γ misclassification rates and in γ/n ratio of incident fields can distort the neutron pulse-height response of scintillators and these distortions can in turn cause large errors in unfolded spectra. New applications in arms-control verification call for detection of lower-energy neutrons, for which PSD is particularly problematic. In this article, we propose techniques for removing distortions on pulse-height response that result from the merging of PSD distributions in the low-pulse-height region. These techniques take advantage of the repeatable shapes of PSD distributions that are governed by the counting statistics of scintillation-photon populations. We validate the proposed techniques using accelerator-based time-of-flight measurements and then demonstrate them by unfolding the Watt spectrum from measurement with a 252Cf neutron source.

Antithrombotic Effect of Antisense Factor XI Oligonucleotide Treatment in Primates

PubMed Central

Crosby, Jeffrey R.; Marzec, Ulla; Revenko, Alexey S.; Zhao, Chenguang; Gao, Dacao; Matafonov, Anton; Gailani, David; MacLeod, A. Robert; Tucker, Erik I.; Gruber, Andras; Hanson, Stephen R.; Monia, Brett P.

2013-01-01

Objective During coagulation, factor IX (FIX) is activated by two distinct mechanisms mediated by the active proteases of either factors VII (FVIIa) or XI (FXIa). Both coagulation factors may contribute to thrombosis; factor XI, however, plays only a limited role in the arrest of bleeding. Therefore, therapeutic targeting of FXI may produce an antithrombotic effect with relatively low hemostatic risk. Approach and Results We have reported that reducing FXI levels with FXI antisense oligonucleotides (ASOs) produces antithrombotic activity in mice, and that administration of FXI ASOs to primates decreases circulating FXI levels and activity in a dose- and time-dependent manner. Here we evaluated the relationship between FXI plasma levels and thrombogenicity in an established baboon model of thrombosis and hemostasis. In previous studies with this model, antibody-induced inhibition of FXI produced potent antithrombotic effects. In the present report, ASO-mediated reduction of FXI plasma levels by ≥50% resulted in a demonstrable and sustained antithrombotic effect without an increased risk of bleeding. Conclusion These results indicate that reducing FXI levels using ASOs is a promising alternative to direct FXI inhibition, and that targeting FXI may be potentially safer than conventional antithrombotic therapies that can markedly impair primary hemostasis. PMID:23559626

Teaching Authorial Style and Literary Technique: "Exemplo XI" of "El Conde Lucanor"

ERIC Educational Resources Information Center

Bryant, Stacy

2016-01-01

This current study proposes a comparative method of teaching authorial style, using four versions of "Exemplo XI," an often-anthologized tale about the "mago" of Toledo, Don Illán, from the "Conde Lucanor," a series of interlinked tales by the early fourteenth-century author Don Juan Manuel. Teaching a medieval text…

Precision in robotic rectal surgery using the da Vinci Xi system and integrated table motion, a technical note.

PubMed

Panteleimonitis, Sofoklis; Harper, Mick; Hall, Stuart; Figueiredo, Nuno; Qureshi, Tahseen; Parvaiz, Amjad

2017-09-15

Robotic rectal surgery is becoming increasingly more popular among colorectal surgeons. However, time spent on robotic platform docking, arm clashing and undocking of the platform during the procedure are factors that surgeons often find cumbersome and time consuming. The newest surgical platform, the da Vinci Xi, coupled with integrated table motion can help to overcome these problems. This technical note aims to describe a standardised operative technique of single docking robotic rectal surgery using the da Vinci Xi system and integrated table motion. A stepwise approach of the da Vinci docking process and surgical technique is described accompanied by an intra-operative video that demonstrates this technique. We also present data collected from a prospectively maintained database. 33 consecutive rectal cancer patients (24 male, 9 female) received robotic rectal surgery with the da Vinci Xi during the preparation of this technical note. 29 (88%) patients had anterior resections, and four (12%) had abdominoperineal excisions. There were no conversions, no anastomotic leaks and no mortality. Median operation time was 331 (249-372) min, blood loss 20 (20-45) mls and length of stay 6.5 (4-8) days. 30-day readmission rate and re-operation rates were 3% (n = 1). This standardised technique of single docking robotic rectal surgery with the da Vinci Xi is safe, feasible and reproducible. The technological advances of the new robotic system facilitate the totally robotic single docking approach.

Flatness-based control in successive loops for stabilization of heart's electrical activity

NASA Astrophysics Data System (ADS)

Rigatos, Gerasimos; Melkikh, Alexey

2016-12-01

The article proposes a new flatness-based control method implemented in successive loops which allows for stabilization of the heart's electrical activity. Heart's pacemaking function is modeled as a set of coupled oscillators which potentially can exhibit chaotic behavior. It is shown that this model satisfies differential flatness properties. Next, the control and stabilization of this model is performed with the use of flatness-based control implemented in cascading loops. By applying a per-row decomposition of the state-space model of the coupled oscillators a set of nonlinear differential equations is obtained. Differential flatness properties are shown to hold for the subsystems associated with the each one of the aforementioned differential equations and next a local flatness-based controller is designed for each subsystem. For the i-th subsystem, state variable xi is chosen to be the flat output and state variable xi+1 is taken to be a virtual control input. Then the value of the virtual control input which eliminates the output tracking error for the i-th subsystem becomes reference setpoint for the i + 1-th subsystem. In this manner the control of the entire state-space model is performed by successive flatness-based control loops. By arriving at the n-th row of the state-space model one computes the control input that can be actually exerted on the aforementioned biosystem. This real control input of the coupled oscillators' system, contains recursively all virtual control inputs associated with the previous n - 1 rows of the state-space model. This control approach achieves asymptotically the elimination of the chaotic oscillation effects and the stabilization of the heart's pulsation rhythm. The stability of the proposed control scheme is proven with the use of Lyapunov analysis.

The vertical structure and stability of accretion disks surrounding black holes and neutron stars

NASA Technical Reports Server (NTRS)

Milsom, J. A.; Chen, Xingming; Taam, Ronald E.

1994-01-01

The structure and stability of the inner regions of accretion disks surrounding neutron stars and black holes have been investigated. Within the framework of the alpha viscosity prescription for optically thick disks, we assume the viscous stress scales with gas pressure only, and the alpha parameter, which is less than or equal to unity, is formulated as alpha(sub 0)(h/r)(exp n), where h is the local scale height and n and alpha(sub 0) are constants. We neglect advective energy transport associated with radial motions and construct the vertical structure of the disks by assuming a Keplerian rotation law and local hydrostatic and thermal equilibrium. The vertical structures have been calculated with and without convective energy transport, and it has been demonstrated that convection is important especially for mass accretion rates, M-dot, greater than about 0.1 times the Eddington value, M-dot(sub Edd). Although the efficiency of convection is not high, convection significantly modifies the vertical structure of the disk (as compared with a purely radiative model) and leads to lower temperatures at a given M-dot. The results show that the disk can be locally unstable and that for n greater than or = 0.75, an S-shaped relation can exist between M-dot and the column density, sigma, at a given radius. While the lower stable branch (derivative of M-dot/derivative of sigma greater than 0) and middle unstable branch (derivative of M-dot/derivative of sigma less than 0) represent structures for which the gas and radiation pressure dominate respectively, the stable upper branch (derivative of M-dot/derivative of sigma greater than 0) is a consequence of the saturation of alpha. This saturation of alpha can occur for large alpha(sub 0) and at M-dot less than or = M-dot(sub Edd). The instability is found to occur at higher mass accretion rates for neutron stars than for black holes. In particular, the disk is locally unstable for M-dot greater than or = 0.5 M-dot(sub Edd

Changing Student Expectations and Graduate Employment: Case Studies from Xi'an, Shaanxi Province

ERIC Educational Resources Information Center

Moorman, Adam B. R.

2011-01-01

This paper addresses the issue of students' employment expectations, considered a key factor in alleviating graduate unemployment in China. This empirical investigation surveyed students at two higher education institutions in Xi'an, Shaanxi Province, to analyze how expectations were changing. The results contrasted with earlier studies that…

Neutron Nucleic Acid Crystallography.

PubMed

Chatake, Toshiyuki

2016-01-01

The hydration shells surrounding nucleic acids and hydrogen-bonding networks involving water molecules and nucleic acids are essential interactions for the structural stability and function of nucleic acids. Water molecules in the hydration shells influence various conformations of DNA and RNA by specific hydrogen-bonding networks, which often contribute to the chemical reactivity and molecular recognition of nucleic acids. However, X-ray crystallography could not provide a complete description of structural information with respect to hydrogen bonds. Indeed, X-ray crystallography is a powerful tool for determining the locations of water molecules, i.e., the location of the oxygen atom of H2O; however, it is very difficult to determine the orientation of the water molecules, i.e., the orientation of the two hydrogen atoms of H2O, because X-ray scattering from the hydrogen atom is very small.Neutron crystallography is a specialized tool for determining the positions of hydrogen atoms. Neutrons are not diffracted by electrons, but are diffracted by atomic nuclei; accordingly, neutron scattering lengths of hydrogen and its isotopes are comparable to those of non-hydrogen atoms. Therefore, neutron crystallography can determine both of the locations and orientations of water molecules. This chapter describes the current status of neutron nucleic acid crystallographic research as well as the basic principles of neutron diffraction experiments performed on nucleic acid crystals: materials, crystallization, diffraction experiments, and structure determination.

Forward-Backward asymmetry in $$\\Lambda_{b}$$ production and search for the $$\\Xi^{-}_{b}$$ and $$\\Omega^{-}_{b}$$ baryons in $$p\\bar{p}$$ collisions at $$\\sqrt{s} = 1.96$$ TeV

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

Garcia Gonzalez, Jose Andres

We present a search for the heavy-flavor baryonsmore » $$\\Xi_{b}$$ (bsd) and $$\\Omega^{-}_{b}$$ in decays $$\\Xi^{-}_{b}$$→ J/ψ$$\\Xi^{-}_{b}$$ → J/ψΛπ-, J/ψ → μ + μ - and $$\\Omega^{-}_{b}$$ → J/ψ$$\\Omega^{-}_{b}$$ J/ψΛ $$K^{-}_{b}$$, J/ψ → μ + μ - respectively.« less

Observational signatures of neutron stars in low-mass X-ray binaries climbing a stability peak

NASA Astrophysics Data System (ADS)

Kantor, E. M.; Gusakov, M. E.; Chugunov, A. I.

2016-01-01

In the recent papers by Gusakov et al., a new scenario describing evolution of rapidly rotating neutron stars (NSs) in low-mass X-ray binaries was proposed. The scenario accounts for a resonant interaction of normal r-modes with superfluid inertial modes at some specific internal stellar temperatures (`resonance temperatures'). This interaction results in an enhanced damping of r-mode and appearance of the `stability peaks' in the temperature - spin frequency plane, which split the r-mode instability window in the vicinity of the resonance temperatures. The scenario suggests that the hot and rapidly rotating NSs spend most of their life climbing up these peaks and, in particular, are observed there at the moment. We analyse in detail possible observational signatures of this suggestion. In particular, we show that these objects may exhibit `anti-glitches' - sudden frequency jumps on a time-scale of hours-months.

Effects of Dao De Xin Xi Exercise on Balance and Quality of Life in Thai Elderly Women

PubMed Central

Intarakamhang, Patrawut; Chintanaprawasee, Pantipa

2012-01-01

The objective of this study was to evaluate the effects of a 12-week Dao De Xin Xi exercise, modified short forms of Tai Chi, on balance and quality of life in Thai elderly population. Quasi-Experimental research, pretest-posttest one group design was done at Physical Medicine and Rehabilitation Department, Phramongkutklao Hospital. Thai healthy elderly women over the age of 60, requiring regular Dao De Xin Xi exercise were recruited from either patients or workers in the hospital. A 60-minute Dao De Xin Xi exercise class was set as 3 times per week for 12 weeks. At baseline and 12 weeks, participants were tested in their static balance (Single-Leg Stance Timed Test with eyes open and close), dynamic balance (Expanded Timed Up and Go (ETUG) Test). Quality of life was measured by the abbreviated Thai version of the World Health Organization Quality of Life (WHOQOL-BREF) questionnaire. Fourteen females were studied with mean age of 62.8±4.3 years old. The Single-Leg Stance Timed Test with eyes open and close, Expanded Timed Up and Go (ETUG) Test improved significantly (before versus after exercises p <0.001). Significant improvement in quality of life were also found in each 4 domains, including physical health, psychological, social relationship, and environment (before versus after exercises p =0.001, 0.001, 0.004 and 0.005 respectively). No significant improvement was found only in the right Single-Leg Stance Timed Test with eyes close (p =0.091). A three times per week for 12-week Dao De Xin Xi exercise may help Thai elderly women improve both static, dynamic balance and quality of life. PMID:22980114

Effects of Dao De Xin Xi exercise on balance and quality of life in Thai elderly women.

PubMed

Intarakamhang, Patrawut; Chintanaprawasee, Pantipa

2011-12-29

The objective of this study was to evaluate the effects of a 12-week Dao De Xin Xi exercise, modified short forms of Tai Chi, on balance and quality of life in Thai elderly population. Quasi-Experimental research, pretest-posttest one group design was done at Physical Medicine and Rehabilitation Department, Phramongkutklao Hospital. Thai healthy elderly women over the age of 60, requiring regular Dao De Xin Xi exercise were recruited from either patients or workers in the hospital. A 60-minute Dao De Xin Xi exercise class was set as 3 times per week for 12 weeks. At baseline and 12 weeks, participants were tested in their static balance (Single-Leg Stance Timed Test with eyes open and close), dynamic balance (Expanded Timed Up and Go (ETUG) Test). Quality of life was measured by the abbreviated Thai version of the World Health Organization Quality of Life (WHOQOL-BREF) questionnaire. Fourteen females were studied with mean age of 62.8±4.3 years old. The Single-Leg Stance Timed Test with eyes open and close, Expanded Timed Up and Go (ETUG) Test improved significantly (before versus after exercises p <0.001). Significant improvement in quality of life were also found in each 4 domains, including physical health, psychological, social relationship, and environment (before versus after exercises p =0.001, 0.001, 0.004 and 0.005 respectively). No significant improvement was found only in the right Single-Leg Stance Timed Test with eyes close (p =0.091). A three times per week for 12-week Dao De Xin Xi exercise may help Thai elderly women improve both static, dynamic balance and quality of life.

40 CFR Appendix Xi to Part 268 - Metal Bearing Wastes Prohibited From Dilution in a Combustion Unit According to 40 CFR 268.3(c)

Code of Federal Regulations, 2013 CFR

2013-07-01

... Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) LAND DISPOSAL RESTRICTIONS Pt. 268, App. XI Appendix XI to Part 268—Metal Bearing Wastes Prohibited From Dilution in a Combustion... 40 Protection of Environment 28 2013-07-01 2013-07-01 false Metal Bearing Wastes Prohibited From...

40 CFR Appendix Xi to Part 268 - Metal Bearing Wastes Prohibited From Dilution in a Combustion Unit According to 40 CFR 268.3(c)

Code of Federal Regulations, 2014 CFR

2014-07-01

... Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) LAND DISPOSAL RESTRICTIONS Pt. 268, App. XI Appendix XI to Part 268—Metal Bearing Wastes Prohibited From Dilution in a Combustion... 40 Protection of Environment 27 2014-07-01 2014-07-01 false Metal Bearing Wastes Prohibited From...

Neutron lifetime measurements with a large gravitational trap for ultracold neutrons

NASA Astrophysics Data System (ADS)

Serebrov, A. P.; Kolomensky, E. A.; Fomin, A. K.; Krasnoshchekova, I. A.; Vassiljev, A. V.; Prudnikov, D. M.; Shoka, I. V.; Chechkin, A. V.; Chaikovskiy, M. E.; Varlamov, V. E.; Ivanov, S. N.; Pirozhkov, A. N.; Geltenbort, P.; Zimmer, O.; Jenke, T.; Van der Grinten, M.; Tucker, M.

2018-05-01

Neutron lifetime is one of the most important physical constants: it determines parameters of the weak interaction and predictions of primordial nucleosynthesis theory. There remains the unsolved problem of a 3.9σ discrepancy between measurements of this lifetime using neutrons in beams and those with stored ultracold neutrons (UCN). In our experiment we measure the lifetime of neutrons trapped by Earth's gravity in an open-topped vessel. Two configurations of the trap geometry are used to change the mean frequency of UCN collisions with the surfaces; this is achieved by plunging an additional surface into the trap without breaking the vacuum. The trap walls are coated with a hydrogen-less fluorine-containing polymer to reduce losses of UCN. The stability of this coating over multiple thermal cycles between 80 and 300 K was tested. At 80 K, the probability of UCN loss due to collisions with the trap walls is just 1.5% of the probability of β decay. The free neutron lifetime is determined by extrapolation to an infinitely large trap with zero collision frequency. The result of these measurements is τn=881.5 ±0 .7stat ±0 .6syst s which is consistent with the conventional value of 880.2 ± 1.0 s presented by the Particle Data Group. Future prospects for this experiment are in further cooling to 10 K, which will lead to an improved accuracy of measurement. In conclusion we present an analysis of currently available data on various measurements of the neutron lifetime.

The impact on post-operative shoulder function of intraoperative nerve monitoring of cranial nerve XI during modified radical neck dissection.

PubMed

Lanišnik, Boštjan; Žitnik, Lidija; Levart, Primož; Žargi, Miha; Rodi, Zoran

2016-12-01

Intraoperative monitoring of the cranial nerve XI (CN XI) may decrease shoulder disability following modified radical neck dissection. Prospective study was designed comparing results of Constant Shoulder Score (CSS), Shoulder Pain and Disability Index (SPADI) and EMG score of the trapezius muscle (mT) before and after surgery. One side of the neck was monitored during surgery with intraoperative nerve monitor. EMG scores of the mT 6 months postoperatively were statistically better on monitored as compared to the non-monitored side of the neck (p = 0.041), while the differences of the CSS and SPADI were not statistically significant. Patients with better EMG scores of the mT at 6 weeks recuperated better and with smaller decrease of the CSS. Intraoperative monitoring is beneficial at the beginning of the surgeon's learning curve and in the process of familiarizing with anatomical variation of the CN XI.

Stability of triangular lagrangian points in elliptical restricted three body problem under the radiating binary systems

NASA Astrophysics Data System (ADS)

Narayan, A.; Singh, Nutan

2014-10-01

This paper studies the stability of Triangular Lagrangian points in the model of elliptical restricted three body problem, under the assumption that both the primaries are radiating. The model proposed is applicable to the well known binary systems Achird, Luyten, αCen AB, Kruger-60, Xi-Bootis. Conditional stability of the motion around the triangular points exists for 0≤ μ≤ μ ∗, where μ is the mass ratio. The method of averaging due to Grebenikov has been exploited throughout the analysis of stability of the system. The critical mass ratio depends on the combined effects of radiation of both the primaries and eccentricity of this orbit. It is found by adopting the simulation technique that the range of stability decreases as the radiation pressure parameter increases.

Is da Vinci Xi Better than da Vinci Si in Robotic Rectal Cancer Surgery? Comparison of the 2 Generations of da Vinci Systems.

PubMed

Ozben, Volkan; Cengiz, Turgut B; Atasoy, Deniz; Bayraktar, Onur; Aghayeva, Afag; Erguner, Ilknur; Baca, Bilgi; Hamzaoglu, Ismail; Karahasanoglu, Tayfun

2016-10-01

We aimed to compare perioperative outcomes for procedures using the latest generation of da Vinci robot versus its previous version in rectal cancer surgery. Fifty-three patients undergoing robotic rectal cancer surgery between January 2010 and March 2015 were included. Patients were classified into 2 groups (Xi, n=28 vs. Si, n=25) and perioperative outcomes were analyzed. The groups had significant differences including operative procedure, hybrid technique and redocking (P>0.05). In univariate analysis, the Xi group had shorter console times (265.7 vs. 317.1 min, P=0.006) and total operative times (321.6 vs. 360.4 min, P=0.04) and higher number of lymph nodes harvested (27.5 vs. 17.0, P=0.008). In multivariate analysis, Xi robot was associated with a shorter console time (odds ratio: 0.09, P=0.004) with no significant differences regarding other outcomes. Both generations of da Vinci robot led to similar short-term outcomes in rectal cancer surgery, but the Xi robot allowed shorter console times.

A Preliminary Investigation into Critical Thinking of Urban Xi'an High School Students

ERIC Educational Resources Information Center

Zhou, Qing; Wang, Xiang; Yao, Linna

2007-01-01

This paper reports the development of critical thinking of urban high school students in the Chinese city of Xi'an. It presents the assessment of the students' two components of critical thinking: dispositions towards critical thinking and critical thinking skills, using the California Critical Thinking Disposition Inventory and the California…

Localized N, {lambda}, {sigma}, and {xi} single-particle potentials in finite nuclei calculated with SU{sub 6} quark-model baryon-baryon interactions

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

Kohno, M.; Fujiwara, Y.

Localized single-particle potentials for all octet baryons, N, {lambda}, {sigma}, and {xi}, in finite nuclei, {sup 12}C, {sup 16}O, {sup 28}Si, {sup 40}Ca, {sup 56}Fe, and {sup 90}Zr, are calculated using the quark-model baryon-baryon interactions. G matrices evaluated in symmetric nuclear matter in the lowest order Brueckner theory (LOBT) are applied to finite nuclei in local density approximation. Nonlocal potentials are localized by a zero-momentum Wigner transformation. Empirical single-particle properties of the nucleon and the {lambda} hyperon in a nuclear medium have been known to be explained semiquantitatively in the LOBT framework. Attention is focused in the present consideration onmore » predictions for the {sigma} and {xi} hyperons. The unified description for the octet baryon-baryon interactions by the SU{sub 6} quark model enables us to obtain less ambiguous extrapolation to the S=-1 and S=-2 sectors based on the knowledge in the NN sector than other potential models. The {sigma} mean field is shown to be weakly attractive at the surface, but turns out to be repulsive inside, which is consistent with the experimental evidence. The {xi} hyperon s.p. potential is also attractive at the nuclear surface region, and inside it fluctuates around zero. Hence {xi} hypernuclear bound states are unlikely. We also evaluate energy shifts of the {sigma}{sup -} and {xi}{sup -} atomic levels in {sup 28}Si and {sup 56}Fe, using the calculated s.p. potentials.« less

Thermal stability of photovoltaic a-Si:H determined by neutron reflectometry

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

Qviller, A. J., E-mail: atlejq@ife.no; Haug, H.; You, C. C.

2014-12-08

Neutron and X-ray reflectometry were used to determine the layer structure and hydrogen content of thin films of amorphous silicon (a-Si:H) deposited onto crystalline silicon (Si) wafers for surface passivation in solar cells. The combination of these two reflectometry techniques is well suited for non-destructive probing of the structure of a-Si:H due to being able to probe buried interfaces and having sub-nanometer resolution. Neutron reflectometry is also unique in its ability to allow determination of density gradients of light elements such as hydrogen (H). The neutron scattering contrast between Si and H is strong, making it possible to determine themore » H concentration in the deposited a-Si:H. In order to correlate the surface passivation properties supplied by the a-Si:H thin films, as quantified by obtainable effective minority carrier lifetime, photoconductance measurements were also performed. It is shown that the minority carrier lifetime falls sharply when H has been desorbed from a-Si:H by annealing.« less

Improved determination of the neutron lifetime.

PubMed

Yue, A T; Dewey, M S; Gilliam, D M; Greene, G L; Laptev, A B; Nico, J S; Snow, W M; Wietfeldt, F E

2013-11-27

The most precise determination of the neutron lifetime using the beam method was completed in 2005 and reported a result of τ(n)=(886.3±1.2[stat]±3.2[syst]) s. The dominant uncertainties were attributed to the absolute determination of the fluence of the neutron beam (2.7 s). The fluence was measured with a neutron monitor that counted the neutron-induced charged particles from absorption in a thin, well-characterized 6Li deposit. The detection efficiency of the monitor was calculated from the areal density of the deposit, the detector solid angle, and the evaluated nuclear data file, ENDF/B-VI 6Li(n,t)4He thermal neutron cross section. In the current work, we measure the detection efficiency of the same monitor used in the neutron lifetime measurement with a second, totally absorbing neutron detector. This direct approach does not rely on the 6Li(n,t)4He cross section or any other nuclear data. The detection efficiency is consistent with the value used in 2005 but is measured with a precision of 0.057%, which represents a fivefold improvement in the uncertainty. We verify the temporal stability of the neutron monitor through ancillary measurements, allowing us to apply the measured neutron monitor efficiency to the lifetime result from the 2005 experiment. The updated lifetime is τ(n)=(887.7±1.2[stat]±1.9[syst]) s.

[Estimation on value of water and soil conservation of agricultural ecosystems in Xi' an metropolitan, Northwest China].

PubMed

Yang, Wen-yan; Zhou, Zhong-xue

2014-12-01

With the urban eco-environment increasingly deteriorating, the ecosystem services provided by modern urban agriculture are exceedingly significant to maintain and build more suitable environment in a city. Taking Xi' an metropolitan as the study area, based on remote sensing data, DEM data and the economic and social statistics data, the water and soil conservation service of the agricultural ecosystems was valued employing the remote sensing and geographic information system method, covering the reduction values on land waste, soil fertility loss and sediment loss from 2000 to 2011, and analyzed its changes in time and space. The results showed that during the study period, the total value of water and soil conservation service provided by agricultural systems in Xi' an metropolitan was increased by 46,086 and 33.008 billion yuan respectively from period of 2000 to 2005 and from 2005 to 2011. The cultivated land (including grains, vegetables and other farming land), forest (including orchard) and grassland provided higher value on the water and soil conservation service than waters and other land use. Ecosystem service value of water and soil conserva- tion provided by agriculture was gradually decreasing from the southern to the northern in Xi' an metropolitan. There were significantly positive relationship between the ecosystem service value and the vegetation coverage. Forest, orchard and grassland distributed intensively in the southern which had higher vegetation coverage than in northern where covered by more cultivated land, sparse forest and scattered orchard. There were significantly negative correlation between the urbanization level and the value of water and soil conservation. The higher level of urbanization, the lower value there was from built-up area to suburban and to countryside within Xi' an metropolitan.

Physical activity level and associated factors among civil servants in Xi'an, China.

PubMed

Sun, Lijun; Jiang, Xun; Zhao, Xin; Zhang, Yuhai; Xu, Yongyong; Shang, Lei

2016-08-01

This study investigated physical activity levels and associated factors among civil servants in Xi'an, China, to provide reference data for the implementation of health improvement strategies among civil servants. A cross-section study. A random sample of 1000 civil servants aged 18-60 years and employed by the Xi'an civic government was assessed by using the Chinese version of the International Physical Activity Questionnaire. Associations between physical activity and sociodemographic characteristics, family history of chronic disease, and existing disease were evaluated by the Mann-Whitney U-test, Kruskal-Wallis H-test, and binary logistic regression. The response rate was 92.4%. The median physical activity score was 2227 metabolic equivalents of task (MET) minutes per week (interquartile range [IQR]: 1308-3802METmin/week). Among the 924 participants, 7.4% did not meet minimum recommendations for physical activity, 57.3% had moderate activity levels, and 35.4% had high activity levels. Participants spent most of their time on occupational activities (median: 869METmin/week, IQR: 228-1953METmin/week). Female sex (odds ratio [OR]:0.40, 95% confidence interval [CI]:0.29-0.55), age≥51 years (OR: 0.45, 95%CI: 0.27-0.75), and family history of chronic disease (OR: 0.67, 95%CI: 0.48-0.94) were associated with significantly lower odds of a high activity level. Most civil servants in Xi'an, China, have moderate activity levels. Some have high activity levels, but few engage in vigorous-intensity physical activity. Interventions to encourage a high level of physical activity are needed, especially for women, older civil servants, and those with family histories of chronic disease. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Role of strangeness to the neutron star mass and cooling

NASA Astrophysics Data System (ADS)

Lee, Chang-Hwan; Lim, Yeunhwan; Hyun, Chang Ho; Kwak, Kyujin

2018-01-01

Neutron star provides unique environments for the investigation of the physics of extreme dense matter beyond normal nuclear saturation density. In such high density environments, hadrons with strange quarks are expected to play very important role in stabilizing the system. Kaons and hyperons are the lowest mass states with strangeness among meson and bayron families, respectively. In this work, we investigate the role of kaons and hyperons to the neutron star mass, and discuss their role in the neutron star cooling.

Secondary Ion Mass Spectrometry SIMS XI

NASA Astrophysics Data System (ADS)

Gillen, G.; Lareau, R.; Bennett, J.; Stevie, F.

2003-05-01

This volume contains 252 contributions presented as plenary, invited and contributed poster and oral presentations at the 11th International Conference on Secondary Ion Mass Spectrometry (SIMS XI) held at the Hilton Hotel, Walt Disney World Village, Orlando, Florida, 7 12 September, 1997. The book covers a diverse range of research, reflecting the rapid growth in advanced semiconductor characterization, ultra shallow depth profiling, TOF-SIMS and the new areas in which SIMS techniques are being used, for example in biological sciences and organic surface characterization. Papers are presented under the following categories: Isotopic SIMS Biological SIMS Semiconductor Characterization Techniques and Applications Ultra Shallow Depth Profiling Depth Profiling Fundamental/Modelling and Diffusion Sputter-Induced Topography Fundamentals of Molecular Desorption Organic Materials Practical TOF-SIMS Polyatomic Primary Ions Materials/Surface Analysis Postionization Instrumentation Geological SIMS Imaging Fundamentals of Sputtering Ion Formation and Cluster Formation Quantitative Analysis Environmental/Particle Characterization Related Techniques These proceedings provide an invaluable source of reference for both newcomers to the field and experienced SIMS users.

Energy levels and radiative rates for transitions in Co XI

NASA Astrophysics Data System (ADS)

Aggarwal, K. M.; Keenan, F. P.; Msezane, A. Z.

2007-10-01

Aims: In this paper we report calculations for energy levels and radiative rates for transitions in Co xi. Methods: The General purpose Relativistic Atomic Structure Package (grasp) and the Flexible Atomic Code (fac) have been adopted for the calculations of energy levels and radiative rates. Results: Energies for the lowest 287 levels of Co xi, including those among the (1s^22s^22p^6) 3s^23p^5, 3s3p^6, 3s^23p^43d, 3s3p^53d, 3s^23p^33d^2, and 3s^23p^44s configurations, are reported. Additionally, radiative rates and oscillator strengths are reported for all electric dipole (E1) transitions with f ≥ 10-5 among these levels, and similar results for magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions are reported only for those with f≥10-8. Comparisons are made with the available results in the literature, and the accuracy of the present data is assessed. Finally, lifetimes for all excited levels are also listed, although measurements are presently available for only one of these. Tables 1 and 3-6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/473/995

Simultaneous neutron scattering and Raman scattering.

PubMed

Adams, Mark A; Parker, Stewart F; Fernandez-Alonso, Felix; Cutler, David J; Hodges, Christopher; King, Andrew

2009-07-01

The capability to make simultaneous neutron and Raman scattering measurements at temperatures between 1.5 and 450 K has been developed. The samples to be investigated are attached to one end of a custom-made center-stick suitable for insertion into a 100 mm-bore cryostat. The other end of the center-stick is fiber-optically coupled to a Renishaw in Via Raman spectrometer incorporating a 300 mW Toptica 785 nm wavelength stabilized diode laser. The final path for the laser beam is approximately 1.3 m in vacuo within the center-stick followed by a focusing lens close to the sample. Raman scattering measurements with a resolution of 1 to 4 cm(-1) can be made over a wide range (100-3200 cm(-1)) at the same time as a variety of different types of neutron scattering measurements. In this work we highlight the use of inelastic neutron scattering and neutron diffraction in conjunction with the Raman for studies of the globular protein lysozyme.

Ecosystem Services Insights into Water Resources Management in China: A Case of Xi'an City.

PubMed

Liu, Jingya; Li, Jing; Gao, Ziyi; Yang, Min; Qin, Keyu; Yang, Xiaonan

2016-11-24

Global climate and environmental changes are endangering global water resources; and several approaches have been tested to manage and reduce the pressure on these decreasing resources. This study uses the case study of Xi'an City in China to test reasonable and effective methods to address water resource shortages. The study generated a framework combining ecosystem services and water resource management. Seven ecosystem indicators were classified as supply services, regulating services, or cultural services. Index values for each indicator were calculated, and based on questionnaire results, each index's weight was calculated. Using the Likert method, we calculated ecosystem service supplies in every region of the city. We found that the ecosystem's service capability is closely related to water resources, providing a method for managing water resources. Using Xi'an City as an example, we apply the ecosystem services concept to water resources management, providing a method for decision makers.

Direct Urca Processes Involving Proton 1 S 0 Superfluidity in Neutron Star Cooling

NASA Astrophysics Data System (ADS)

Xu, Yan; Yu, Zi; Zhang, Xiao-Jun; Fan, Cun-Bo; Liu, Guang-Zhou; Zhao, En-Guang; Huang, Xiu-Lin; Liu, Cheng-Zhi

2018-04-01

A detailed description of the baryon direct Urca processes A: n\\to p+e+{\\bar{ν }}e, B: Λ \\to p+e+{\\bar{ν }}e and C: {\\Xi }-\\to Λ +e+{\\bar{ν }}e related to the neutron star cooling is given in the relativistic mean field approximation. The contributions of the reactions B and C on the neutrino luminosity are calculated by means of the relativistic expressions of the neutrino energy losses. Our results show that the total neutrino luminosities of the reactions A, B and C within the mass range (1.603–2.067) M⊙ ((1.515–1.840) M⊙ for TM1 model) for GM1 model are larger than the corresponding values for neutron star without hyperons. Furthermore, although the neutrino emissivity of the reaction A is suppressed with the appearance of the proton 1 S 0 superfluid, the contribution of the reactions B and C can still quicken a massive neutron star cooling. In particular, the reaction C in PSR J1614-2230 and J0348+0432 is not suppressed by the proton 1 S 0 superfluid due to the higher threshold density of the reaction C, which will further speed up the two pulsars cooling. Supported by the National Natural Science Foundation of China under Grant Nos. 11447165, 11373047, 11404336 and U1731240, Youth Innovation Promotion Association, CAS under Grant No. 2016056, and the Development Project of Science and Technology of Jilin Province under Grant No. 20180520077JH

Study on the adult physique with the Heath-Carter anthropometric somatotype in the Han of Xi'an, China.

PubMed

Yang, Li-Tao; Wang, Ning; Li, Zeng-Xian; Liu, Cui; He, Xin; Zhang, Jian-Fei; Han, Hua; Wen, You-Feng; Qian, Yi-Hua; Xi, Huan-Jiu

2016-03-01

The study of somatotypes has important significance for medical and physical anthropology as well as sports science. The aim of this study was to understand the somatotype components of the Han population in Xi'an and compare the somatotypes of the Han and five other nationalities in China. The study sample consisted of 429 people of Han nationality (207 males, 222 females) from Xi'an, China, aged ≥20 years old. The Heath-Carter anthropometric method was employed. We evaluated the differences in age and sex by one-way ANOVA and t test. A comparison of somatotypes between the Han and other nationalities was made using the U test. The results showed that the male and female samples all could be classified as having a mesomorphic endomorph profile. The difference in endomorphy was strongest between sexes in all age groups (P < 0.01). There were prominent differences in mesomorphy and ectomorphy between males and females in the 50-59- and ≥60-year-old age groups. In females, the differences in somatotype components appeared to be distinguished between ages (P < 0.01 or P < 0.05). However, in males, there were prominent differences in somatotype components between the 20-29 year olds and all other age groups (P < 0.01 or P < 0.05) except for between those 20-29 and ≥60 years old in endomorphy. Compared with the other five nationalities, there were prominent differences in somatotype components between males and females. These results suggest that the somatotype of the Han population in Xi'an, China, has a predominantly mesomorphic endomorph profile. The endomorphic component shows distinct differences between ages and genders, respectively. Additionally, there are distinct differences in the somatotype components between Xi'an Han and five other nationalities in China in males and females.

Resolving the xi Boo Binary with Chandra, and Revealing the Spectral Type Dependence of the Coronal "Fip Effect"

NASA Technical Reports Server (NTRS)

Wood, Brian E.; Linsky, Jeffrey L.

2010-01-01

On 2008 May 2, Chandra observed the X-ray spectrum of xi Boo (G8 V+K4 V), resolving the binary for the first time in X-rays and allowing the coronae of the two stars to be studied separately. With the contributions of ξ Boo A and B to the system's total X-ray emission now observationally established (88.5% and 11.5% respectively), consideration of mass loss measurements for GK dwarfs of various activity levels (including one for xi Boo) leads to the surprising conclusion that xi Boo B may dominate the wind from the binary, with xi Boo A's wind being very weak despite its active corona. Emission measure (EM) distributions and coronal abundances are computed for both stars and compared with Chandra measurements of other moderately active stars with G8-K5 spectral types, all of which exhibit a narrow peak in EM near log T = 6.6, indicating that the coronal heating process in these stars has a strong preference for this temperature. As is the case for the Sun and many other stars, our sample of stars shows coronal abundance anomalies dependent on the first ionization potential (FIP) of the element. We see no dependence of the degree of FIP effect on activity, but there is a dependence on spectral type, a correlation that becomes more convincing when moderately active main-sequence stars with a broader range of spectral types are considered. This clear dependence of coronal abundances on spectral type weakens if the stellar sample is allowed to be contaminated by evolved stars, interacting binaries or extremely active stars with logLX 29, explaining why this correlation has not been recognized in the past.

Role of high-spin hyperon resonances in the reaction of $$\\gamma p \\to K^+ K^+ \\Xi^-$$

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

J. Ka Shing Man, Yongseok Oh, K. Nakayama

The recent data taken by the CLAS Collaboration at the Thomas Jefferson National Accelerator Facility for the reaction ofmore » $$\\gamma p \\to K^+ K^+ \\Xi^-$$ are reanalyzed within a relativistic meson-exchange model of hadronic interactions. The present model is an extension of the one developed in an earlier work by Nakayama, Oh, and Haberzettl [Phys. Rev. C 74, 035205 (2006)]. In particular, the role of the spin-5/2 and -7/2 hyperon resonances, which were not included in the previous model, is investigated in the present study. It is shown that the contribution of the $$\\Sigma(2030)$$ hyperon having spin-7/2 and positive parity has a key role to bring the model predictions into a fair agreement with the measured data for the $$K^+\\Xi^-$$ invariant mass distribution.« less

Neutrons on a surface of liquid helium

NASA Astrophysics Data System (ADS)

Grigoriev, P. D.; Zimmer, O.; Grigoriev, A. D.; Ziman, T.

2016-08-01

We investigate the possibility of ultracold neutron (UCN) storage in quantum states defined by the combined potentials of the Earth's gravity and the neutron optical repulsion by a horizontal surface of liquid helium. We analyze the stability of the lowest quantum state, which is most susceptible to perturbations due to surface excitations, against scattering by helium atoms in the vapor and by excitations of the liquid, comprised of ripplons, phonons, and surfons. This is an unusual scattering problem since the kinetic energy of the neutron parallel to the surface may be much greater than the binding energies perpendicular. The total scattering time of these UCNs at 0.7 K is found to exceed 1 h, and rapidly increases with decreasing temperature. Such low scattering rates should enable high-precision measurements of the sequence of discrete energy levels, thus providing improved tests of short-range gravity. The system might also be useful for neutron β -decay experiments. We also sketch new experimental propositions for level population and trapping of ultracold neutrons above a flat horizontal mirror.

Improved Determination of the Neutron Lifetime

NASA Astrophysics Data System (ADS)

Yue, A.

2013-10-01

The most precise determination of the neutron lifetime using the beam method reported a result of τn = (886 . 3 +/- 3 . 4) s. The dominant uncertainties were attributed to the absolute determination of the fluence of the neutron beam (2.7 s). The fluence was determined with a monitor that counted the neutron-induced charged particles from absorption in a thin, well-characterized 6Li deposit. The detection efficiency of the monitor was calculated from the areal density of the deposit, the detector solid angle, and the ENDF/B-VI 6Li(n,t)4He thermal neutron cross section. We have used a second, totally-absorbing neutron detector to directly measure the detection efficiency of the monitor on a monochromatic neutron beam of precisely known wavelength. This method does not rely on the 6Li(n,t)4He cross section or any other nuclear data. The monitor detection efficiency was measured to an uncertainty of 0.06%, which represents a five-fold improvement in uncertainty. We have verified the temporal stability of the monitor with ancillary measurements, and the measured neutron monitor efficiency has been used to improve the fluence determination in the past lifetime experiment. An updated neutron lifetime based on the improved fluence determination will be presented. Work done in collaboration with M. Dewey, D. Gilliam, J. Nico, National Institute of Standards and Technology; G. Greene, University of Tennessee / Oak Ridge National Laboratory; A. Laptev, Los Alamos National Laboratory; W. Snow, Indiana University; and F. Wietfeldt, Tulane University.

Atomic Data and Spectral Line Intensities for Ni XI

NASA Technical Reports Server (NTRS)

Bhatia, A. K.; Landi, E.

2010-01-01

Electron impact collision strengths, energy levels, oscillator strengths and spontaneous radiative decay rates are calculated for Ni XI. We include in the calculations the 10 lowest configurations, corresponding to 164 fine structure levels: 3s(sup 2)3p(sup 6), 3s(sup 2)3p(sup 5)3d, 3s(sup 2)3p(sup 4)3d(sup 2), 3s3p(sup 6)3d, 3s(sup 2)3p(sup 5)4l and 3s3p6 4l with l =.s, p, d. Collision strengths are calculated at five incident energies for all transitions: 7.1, 16.8, 30.2, 48.7 and 74.1 Ry above the threshold of each transition. An additional energy, very close to the transition threshold, has been added, whose value is between 0.06 Ry and 0.25 Ry depending on the lower level. Calculations have been carried out using the Flexible Atomic Code and the distorted wave approximation. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates of the present work, combined with Close Coupling collision excitation rate coefficient available in the literature for the lowest 17 levels, statistical equilibrium equations for level populations are solved at electron densities covering the 10(exp 8)-10(exp 14) cu cm range and at an electron temperature of logT(sub c)(K)=6.1, corresponding to the maximum abundance of Ni XI. Spectral line intensities are calculated, and their diagnostic relevance is discussed. This dataset will be made available in the next version of the CHIANTI database.

Total robotic radical rectal resection with da Vinci Xi system: single docking, single phase technique.

PubMed

Tamhankar, Anup Sunil; Jatal, Sudhir; Saklani, Avanish

2016-12-01

This study aims to assess the advantages of Da Vinci Xi system in rectal cancer surgery. It also assesses the initial oncological outcomes after rectal resection with this system from a tertiary cancer center in India. Robotic rectal surgery has distinct advantages over laparoscopy. Total robotic resection is increasing following the evolution of hybrid technology. The latest Da Vinci Xi system (Intuitive Surgical, Sunnyvale, USA) is enabled with newer features to make total robotic resection possible with single docking and single phase. Thirty-six patients underwent total robotic resection in a single phase and single docking. We used newer port positions in a straight line. Median distance from the anal verge was 4.5 cm. Median robotic docking time and robotic procedure time were 9 and 280 min, respectively. Median blood loss was 100 mL. One patient needed conversion to an open approach due to advanced disease. Circumferential resection margin and longitudinal resection margins were uninvolved in all other patients. Median lymph node yield was 10. Median post-operative stay was 7 days. There were no intra-operative adverse events. The latest Da Vinci Xi system has made total robotic rectal surgery feasible in single docking and single phase. With the new system, four arm total robotic rectal surgery may replace the hybrid technique of laparoscopic and robotic surgery for rectal malignancies. The learning curve for the new system appears to be shorter than anticipated. Early perioperative and oncological outcomes of total robotic rectal surgery with the new system are promising. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

2010 Neutron Review: ORNL Neutron Sciences Progress Report

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

Bardoel, Agatha A; Counce, Deborah M; Ekkebus, Allen E

2011-06-01

During 2010, the Neutron Sciences Directorate focused on producing world-class science, while supporting the needs of the scientific community. As the instrument, sample environment, and data analysis tools at High Flux Isotope Reactor (HFIR ) and Spallation Neutron Source (SNS) have grown over the last year, so has promising neutron scattering research. This was an exciting year in science, technology, and operations. Some topics discussed are: (1) HFIR and SNS Experiments Take Gordon Battelle Awards for Scientific Discovery - Battelle Memorial Institute presented the inaugural Gordon Battelle Prizes for scientific discovery and technology impact in 2010. Battelle awards the prizesmore » to recognize the most significant advancements at national laboratories that it manages or co-manages. (2) Discovery of Element 117 - As part of an international team of scientists from Russia and the United States, HFIR staff played a pivotal role in the discovery by generating the berkelium used to produce the new element. A total of six atoms of ''ununseptium'' were detected in a two-year campaign employing HFIR and the Radiochemical Engineering Development Center at Oak Ridge National Laboratory (ORNL) and the heavy-ion accelerator capabilities at the Joint Institute for Nuclear Research in Dubna, Russia. The discovery of the new element expands the understanding of the properties of nuclei at extreme numbers of protons and neutrons. The production of a new element and observation of 11 new heaviest isotopes demonstrate the increased stability of super-heavy elements with increasing neutron numbers and provide the strongest evidence to date for the existence of an island of enhanced stability for super-heavy elements. (3) Studies of Iron-Based High-Temperature Superconductors - ORNL applied its distinctive capabilities in neutron scattering, chemistry, physics, and computation to detailed studies of the magnetic excitations of iron-based superconductors (iron pnictides and

Breckinridge Project, initial effort. Report XI, Volume V. Critical review of the design basis. [Critical review

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

None

1982-01-01

Report XI, Technical Audit, is a compendium of research material used during the Initial Effort in making engineering comparisons and decisions. Volumes 4 and 5 of Report XI present those studies which provide a Critical Review of the Design Basis. The Critical Review Report, prepared by Intercontinental Econergy Associates, Inc., summarizes findings from an extensive review of the data base for the H-Coal process design. Volume 4 presents this review and assessment, and includes supporting material; specifically, Design Data Tabulation (Appendix A), Process Flow Sheets (Appendix B), and References (Appendix C). Volume 5 is a continuation of the references ofmore » Appendix C. Studies of a proprietary nature are noted and referenced, but are not included in these volumes. They are included in the Limited Access versions of these reports and may be reviewed by properly cleared personnel in the offices of Ashland Synthetic Fuels, Inc.« less

Estimating PM2.5 in Xi'an , China Using Aerosol Optical Depth of Npp Viirs Data and Meteorological Measurements

NASA Astrophysics Data System (ADS)

Zhang, K.; Yang, Z.; Zheng, J.; Jiao, J.; Gao, W.

2018-04-01

In recent years, the air pollution is becoming more and more serious, which not only causes the decrease of the visibility, but also affects the human health. As the most important pollutant particulate matter, remote sensing satellite measurements have been widely used to estimate PM2.5 concentration on the ground. Visible Infrared Imaging Radiometer Suite (VIIRS) is one of the instruments which is taken in the National Polar-orbiting Partnership (NPP) satellite. In this study, VIIRS was used to retrieve aerosol optical depth (AOD) with the way of dark pixels, and several other major meteorological variables (wind speed, relative humidity, NO2 concentration, ground surface relative humidity and planetary boundary layer height) were combined with AOD to construct a nonlinear multiple regression mode for establishing the relationship between AOD and PM2.5 concentration. The North Basin of Shaanxi province of China, which includes Xi'an, is located in the north of Qinling Mountains, south of the Loess Plateau, and in the central of Weihe basin, with special structure and other adverse weather conditions (static wind, less rain) to cause the frequent haze weather in Xi'an. Xi'an city was selected as the area of the experiment due to its particularity. This research obtained the AOD results from August 1, 2013 to October 30, 2013. The inversion results were compared with ground-based PM2.5 concentration date from air quality monitoring station of Xi'an. The result showed that there is a significant correlation between the two, and the correlation coefficient is 0.783. The inversion result verified that the model of VIIRS data agreed well AOD, which could be used to estimate the surface PM2.5 concentration and monitor the regional air quality.

Proteins QSAR with Markov average electrostatic potentials.

PubMed

González-Díaz, Humberto; Uriarte, Eugenio

2005-11-15

Classic physicochemical and topological indices have been largely used in small molecules QSAR but less in proteins QSAR. In this study, a Markov model is used to calculate, for the first time, average electrostatic potentials xik for an indirect interaction between aminoacids placed at topologic distances k within a given protein backbone. The short-term average stochastic potential xi1 for 53 Arc repressor mutants was used to model the effect of Alanine scanning on thermal stability. The Arc repressor is a model protein of relevance for biochemical studies on bioorganics and medicinal chemistry. A linear discriminant analysis model developed correctly classified 43 out of 53, 81.1% of proteins according to their thermal stability. More specifically, the model classified 20/28, 71.4% of proteins with near wild-type stability and 23/25, 92.0% of proteins with reduced stability. Moreover, predictability in cross-validation procedures was of 81.0%. Expansion of the electrostatic potential in the series xi0, xi1, xi2, and xi3, justified the use of the abrupt truncation approach, being the overall accuracy >70.0% for xi0 but equal for xi1, xi2, and xi3. The xi1 model compared favorably with respect to others based on D-Fire potential, surface area, volume, partition coefficient, and molar refractivity, with less than 77.0% of accuracy [Ramos de Armas, R.; González-Díaz, H.; Molina, R.; Uriarte, E. Protein Struct. Func. Bioinf.2004, 56, 715]. The xi1 model also has more tractable interpretation than others based on Markovian negentropies and stochastic moments. Finally, the model is notably simpler than the two models based on quadratic and linear indices. Both models, reported by Marrero-Ponce et al., use four-to-five time more descriptors. Introduction of average stochastic potentials may be useful for QSAR applications; having xik amenable physical interpretation and being very effective.

Full Robotic Colorectal Resections for Cancer Combined With Other Major Surgical Procedures: Early Experience With the da Vinci Xi.

PubMed

Morelli, Luca; Di Franco, Gregorio; Guadagni, Simone; Palmeri, Matteo; Gianardi, Desirée; Bianchini, Matteo; Moglia, Andrea; Ferrari, Vincenzo; Caprili, Giovanni; D'Isidoro, Cristiano; Melfi, Franca; Di Candio, Giulio; Mosca, Franco

2017-08-01

The da Vinci Xi has been developed to overcome some of the limitations of the previous platform, thereby increasing the acceptance of its use in robotic multiorgan surgery. Between January 2015 and October 2015, 10 patients with synchronous tumors of the colorectum and others abdominal organs underwent robotic combined resections with the da Vinci Xi. Trocar positions respected the Universal Port Placement Guidelines provided by Intuitive Surgical for "left lower quadrant," with trocars centered on the umbilical area, or shifted 2 to 3 cm to the right or to the left, depending on the type of combined surgical procedure. All procedures were completed with the full robotic technique. Simultaneous procedures in same quadrant or left quadrant and pelvis, or left/right and upper, were performed with a single docking/single targeting approach; in cases of left/right quadrant or right quadrant/pelvis, we performed a dual-targeting operation. No external collisions or problems related to trocar positions were noted. No patient experienced postoperative surgical complications and the mean hospital stay was 6 days. The high success rate of full robotic colorectal resection combined with other surgical interventions for synchronous tumors, suggest the efficacy of the da Vinci Xi in this setting.

Stabilized wide bandgap MAPbBr xI 3-x perovskite by enhanced grain size and improved crystallinity

DOE PAGES

Hu, Miao; Bi, Cheng; Yuan, Yongbo; ...

2015-12-07

In this study, the light instability of CH 3NH 3PbI xBr 3–x has been raised one of the biggest challenges for its application in tandem solar cells. Here we show that an improved crystallinity and grain size of CH 3NH 3PbI xBr 3–x films could stabilize these materials under one sun illumination, improving both the efficiency and stability of the wide-bandgap perovskite solar cells.

Novel diamond cells for neutron diffraction using multi-carat CVD anvils.

PubMed

Boehler, R; Molaison, J J; Haberl, B

2017-08-01

Traditionally, neutron diffraction at high pressure has been severely limited in pressure because low neutron flux required large sample volumes and therefore large volume presses. At the high-flux Spallation Neutron Source at the Oak Ridge National Laboratory, we have developed new, large-volume diamond anvil cells for neutron diffraction. The main features of these cells are multi-carat, single crystal chemical vapor deposition diamonds, very large diffraction apertures, and gas membranes to accommodate pressure stability, especially upon cooling. A new cell has been tested for diffraction up to 40 GPa with an unprecedented sample volume of ∼0.15 mm 3 . High quality spectra were obtained in 1 h for crystalline Ni and in ∼8 h for disordered glassy carbon. These new techniques will open the way for routine megabar neutron diffraction experiments.

Stability analysis of BWR nuclear-coupled thermal-hyraulics using a simple model

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

Karve, A.A.; Rizwan-uddin; Dorning, J.J.

1995-09-01

A simple mathematical model is developed to describe the dynamics of the nuclear-coupled thermal-hydraulics in a boiling water reactor (BWR) core. The model, which incorporates the essential features of neutron kinetics, and single-phase and two-phase thermal-hydraulics, leads to simple dynamical system comprised of a set of nonlinear ordinary differential equations (ODEs). The stability boundary is determined and plotted in the inlet-subcooling-number (enthalpy)/external-reactivity operating parameter plane. The eigenvalues of the Jacobian matrix of the dynamical system also are calculated at various steady-states (fixed points); the results are consistent with those of the direct stability analysis and indicate that a Hopf bifurcationmore » occurs as the stability boundary in the operating parameter plane is crossed. Numerical simulations of the time-dependent, nonlinear ODEs are carried out for selected points in the operating parameter plane to obtain the actual damped and growing oscillations in the neutron number density, the channel inlet flow velocity, and the other phase variables. These indicate that the Hopf bifurcation is subcritical, hence, density wave oscillations with growing amplitude could result from a finite perturbation of the system even where the steady-state is stable. The power-flow map, frequently used by reactor operators during start-up and shut-down operation of a BWR, is mapped to the inlet-subcooling-number/neutron-density (operating-parameter/phase-variable) plane, and then related to the stability boundaries for different fixed inlet velocities corresponding to selected points on the flow-control line. The stability boundaries for different fixed inlet subcooling numbers corresponding to those selected points, are plotted in the neutron-density/inlet-velocity phase variable plane and then the points on the flow-control line are related to their respective stability boundaries in this plane.« less

Port positioning and docking for single-stage totally robotic dissection for rectal cancer surgery with the Si and Xi Da Vinci Surgical System.

PubMed

Toh, James Wei Tatt; Kim, Seon-Hahn

2017-11-04

We have previously reported our technique of single-docking totally robotic dissection for rectal cancer surgery using the Da Vinci ® Si Surgical System in 2009. However, we have since optimised our port placement for the Si system and have developed a novel configuration of port placement and docking for the Da Vinci ® Xi Surgical System. We have performed over 700 cases using this technique with the Si system and have used our Xi technique since 2016 for totally robotic dissection for rectal cancer. We have kept the configuration of port placements for both the Xi and Si system as similar as possible, with the priorities to avoid arm collisions as well as to provide a workable port configuration of two left-handed instruments and one right-handed instrument. To date, there have had no major complications or arm collisions related to this technique of docking, port positioning and instrument placement.

Analysis of magnesium XI line profiles from solar active regions

NASA Technical Reports Server (NTRS)

Blake, R. L.; Cowan, R. D.; Felthauser, H.; Fenimore, E. E.; Hockaday, M. P.; Bely-Dubau, F.; Faucher, P.; Steenman-Clark, L.

1984-01-01

High-resolution solar spectra of the Mg XI 1s2 1S0-1s2p 1P1 resonance line at 9.169 A and the associated nearby satellite lines obtained from two rocket-borne crystal spectrometer measurements are presented. Comparisons with two independent sets of theoretical calculations for the 1s2nl-1s2pnl dielectronic satellite lines with n = 3-7 indicate electron temperatures of 4-4.5 million K. Measured line widths indicate either that the ion temperature exceeds the electron temperature by about a million K or that about 28 km/s of turbulence is present.

On the Maximum Mass of Differentially Rotating Neutron Stars

NASA Astrophysics Data System (ADS)

Baumgarte, Thomas W.; Shapiro, Stuart L.; Shibata, Masaru

2000-01-01

We construct relativistic equilibrium models of differentially rotating neutron stars and show that they can support significantly more mass than their nonrotating or uniformly rotating counterparts. We dynamically evolve such ``hypermassive'' models in full general relativity and show that there do exist configurations that are dynamically stable against radial collapse and bar formation. Our results suggest that the remnant of binary neutron star coalescence may be temporarily stabilized by differential rotation, leading to delayed collapse and a delayed gravitational wave burst.

Identification and functional activity of a staphylocoagulase type XI variant originating from staphylococcal food poisoning isolates.

PubMed

Suzuki, Y; Matsushita, S; Kubota, H; Kobayashi, M; Murauchi, K; Higuchi, Y; Kato, R; Hirai, A; Sadamasu, K

2016-09-01

Staphylocoagulase, an extracellular protein secreted by Staphylococcus aureus, has been used as an epidemiological marker. At least 12 serotypes and 24 genotypes subdivided on the basis of nucleotide sequence have been reported to date. In this study, we identified a novel staphylocoagulase nucleotide sequence, coa310, from staphylococcal food poisoning isolates that had the ability to coagulate plasma, but could not be typed using the conventional method. The protein encoded by coa310 contained the six fundamental conserved domains of staphylocoagulase. The full-length nucleotide sequence of coa310 shared the highest similarity (77·5%) with that of staphylocoagulase-type (SCT) XIa. The sequence of the D1 region, which would be responsible for the determination of SCT, shared the highest similarity (91·8%) with that of SCT XIa. These results suggest that coa310 is a novel variant of SCT XI. Moreover, we demonstrated that coa310 encodes a functioning coagulase, by confirming the coagulating activity of the recombinant protein expressed from coa310. This is the first study to directly demonstrate that Coa310, a putative SCT XI, has coagulating activity. These findings may be useful for the improvement of the staphylocoagulase-typing method, including serotyping and genotyping. This is the first study to identify a novel variant of staphylocoagulase type XI based on its nucleotide sequence and to demonstrate coagulating activity in the variant using a recombinant protein. Elucidation of the variety of staphylocoagulases will provide suggestions for further improvement of the staphylocoagulase-typing method and contribute to our understanding of the epidemiologic characterization of Staphylococcus aureus. © 2016 The Society for Applied Microbiology.

Origin of Stability in Particle Sedimentation

NASA Technical Reports Server (NTRS)

Segre, Philip N.

2003-01-01

Particle Image Velocimetry (PIV) is used to study the slow settling motions of spheres in suspensions ranging from dilute to highly concentrated, 0.0001 less than phi less than 0.50. During sedimentation, particle velocity fluctuations are found to be organized into regions of characteristic size xi approximately 11 a phi (exp -1/3). A simple model, based upon buoyant mass fluctuations DELTAm given by random density fluctuations in a region of size xi, accurately predicts the magnitudes of the velocity fluctuations DELTAV. We also find a new universal relation for particle diffusion during sedimentation. It can be written in a Stokes-Einstein form as Dapproximately(DELTAmxi)/(6pietaxi), where the effective temperature DELTAmgxi is the gravitational potential energy of density fluctuations. In addition related experiments examining inertial effects and transient states, that are aimed at uncovering the origin of the new lengthscale xi, will also be given.

Noise source and reactor stability estimation in a boiling water reactor using a multivariate autoregressive model

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

Kanemoto, S.; Andoh, Y.; Sandoz, S.A.

1984-10-01

A method for evaluating reactor stability in boiling water reactors has been developed. The method is based on multivariate autoregressive (M-AR) modeling of steady-state neutron and process noise signals. In this method, two kinds of power spectral densities (PSDs) for the measured neutron signal and the corresponding noise source signal are separately identified by the M-AR modeling. The closed- and open-loop stability parameters are evaluated from these PSDs. The method is applied to actual plant noise data that were measured together with artificial perturbation test data. Stability parameters identified from noise data are compared to those from perturbation test data,more » and it is shown that both results are in good agreement. In addition to these stability estimations, driving noise sources for the neutron signal are evaluated by the M-AR modeling. Contributions from void, core flow, and pressure noise sources are quantitatively evaluated, and the void noise source is shown to be the most dominant.« less

Novel diamond cells for neutron diffraction using multi-carat CVD anvils

DOE PAGES

Boehler, R.; Molaison, J. J.; Haberl, B.

2017-08-17

Traditionally, neutron diffraction at high pressure has been severely limited in pressure because low neutron flux required large sample volumes and therefore large volume presses. At the high-flux Spallation Neutron Source at the Oak Ridge National Laboratory, we have developed in this paper new, large-volume diamond anvil cells for neutron diffraction. The main features of these cells are multi-carat, single crystal chemical vapor deposition diamonds, very large diffraction apertures, and gas membranes to accommodate pressure stability, especially upon cooling. A new cell has been tested for diffraction up to 40 GPa with an unprecedented sample volume of ~0.15 mm 3.more » High quality spectra were obtained in 1 h for crystalline Ni and in ~8 h for disordered glassy carbon. Finally, these new techniques will open the way for routine megabar neutron diffraction experiments.« less

Characterization of a neutron sensitive MCP/Timepix detector for quantitative image analysis at a pulsed neutron source

NASA Astrophysics Data System (ADS)

Watanabe, Kenichi; Minniti, Triestino; Kockelmann, Winfried; Dalgliesh, Robert; Burca, Genoveva; Tremsin, Anton S.

2017-07-01

The uncertainties and the stability of a neutron sensitive MCP/Timepix detector when operating in the event timing mode for quantitative image analysis at a pulsed neutron source were investigated. The dominant component to the uncertainty arises from the counting statistics. The contribution of the overlap correction to the uncertainty was concluded to be negligible from considerations based on the error propagation even if a pixel occupation probability is more than 50%. We, additionally, have taken into account the multiple counting effect in consideration of the counting statistics. Furthermore, the detection efficiency of this detector system changes under relatively high neutron fluxes due to the ageing effects of current Microchannel Plates. Since this efficiency change is position-dependent, it induces a memory image. The memory effect can be significantly reduced with correction procedures using the rate equations describing the permanent gain degradation and the scrubbing effect on the inner surfaces of the MCP pores.

Chinese Military Reform in the Age of Xi Jinping: Drivers, Challenges, and Implications

DTIC Science & Technology

2017-03-01

refused to obey commands, Xi has em - phasized it in a way that his immediate predecessors did not. For instance, loyalty to the Party was a major...disposal and appears to be em - ploying them in a reasonably strategic fashion to promote the military reforms. However, some of these tools require his...exercise operational control over units. ■■ Rocket Force C2 and scope of authority. Although authoritative Chinese sources em - phasize consistency in the

Optical spring stabilization

NASA Astrophysics Data System (ADS)

Lough, James D.

The Advanced LIGO detectors will soon be online with enough sensitivity to begin detecting gravitational waves, based on conservative estimates of the rate of neutron star inspirals. These first detections are sure to be significant, however, we will always strive to do better. More questions will be asked about the nature of neutron star material, rates of black hole inspirals, electromagnetic counterparts, etc. To begin to answer all of the questions aLIGO will bring us we will need even better sensitivity in future gravitational wave detectors. This thesis addresses one aspect that will limit us in the future: angular stability of the test masses. Angular stability in advanced LIGO uses an active feedback system. We are proposing to replace the active feedback system with a passive one, eliminating sensing noise contributions. This technique uses the radiation pressure of light inside a cavity as a stable optical spring, fundamentally the same as technique developed by Corbitt, et al. with an additional degree of freedom. I will review the theory of the one dimensional technique and discuss the multidimensional control theory and angular trap setup. I will then present results from the one-dimensional trap which we have built and tested. And propose improvements for the angular trap experiment. Along the way we have discovered an interesting coupling with thermal expansion due to round trip absorption in the high reflective coatings. The front surface HR coating limits our spring stability in this experiment due to the high circulating power and small beam spot size.

Using a Tandem Pelletron accelerator to produce a thermal neutron beam for detector testing purposes.

PubMed

Irazola, L; Praena, J; Fernández, B; Macías, M; Bedogni, R; Terrón, J A; Sánchez-Nieto, B; Arias de Saavedra, F; Porras, I; Sánchez-Doblado, F

2016-01-01

Active thermal neutron detectors are used in a wide range of measuring devices in medicine, industry and research. For many applications, the long-term stability of these devices is crucial, so that very well controlled neutron fields are needed to perform calibrations and repeatability tests. A way to achieve such reference neutron fields, relying on a 3 MV Tandem Pelletron accelerator available at the CNA (Seville, Spain), is reported here. This paper shows thermal neutron field production and reproducibility characteristics over few days. Copyright © 2015 Elsevier Ltd. All rights reserved.

An Improved Neutron Transport Algorithm for HZETRN

NASA Technical Reports Server (NTRS)

Slaba, Tony C.; Blattnig, Steve R.; Clowdsley, Martha S.; Walker, Steven A.; Badavi, Francis F.

2010-01-01

Long term human presence in space requires the inclusion of radiation constraints in mission planning and the design of shielding materials, structures, and vehicles. In this paper, the numerical error associated with energy discretization in HZETRN is addressed. An inadequate numerical integration scheme in the transport algorithm is shown to produce large errors in the low energy portion of the neutron and light ion fluence spectra. It is further shown that the errors result from the narrow energy domain of the neutron elastic cross section spectral distributions, and that an extremely fine energy grid is required to resolve the problem under the current formulation. Two numerical methods are developed to provide adequate resolution in the energy domain and more accurately resolve the neutron elastic interactions. Convergence testing is completed by running the code for various environments and shielding materials with various energy grids to ensure stability of the newly implemented method.

Study on High Speed Lithium Jet For Neutron Source of Boron Neutron Capture Therapy (BNCT)

NASA Astrophysics Data System (ADS)

Takahashi, Minoru; Kobayashi, Tooru; Zhang, Mingguang; Mák, Michael; Štefanica, Jirí; Dostál, Václav; Zhao, Wei

The feasibility study of a liquid lithium type proton beam target was performed for the neutron source of the boron neutron capture therapy (BNCT). As the candidates of the liquid lithium target, a thin sheet jet and a thin film flow on a concave wall were chosen, and a lithium flow experiment was conducted to investigate the hydrodynamic stability of the targets. The surfaces of the jets and film flows with a thickness of 0.5 mm and a width of 50 mm were observed by means of photography. It has been found that a stable sheet jet and a stable film flow on a concave wall can be formed up to certain velocities by using a straight nozzle and a curved nozzle with the concave wall, respectively.

University of Nottingham Ningbo China and Xi'an Jiaotong-Liverpool University: Globalization of Higher Education in China

ERIC Educational Resources Information Center

Feng, Yi

2013-01-01

This essay studies the University of Nottingham Ningbo China and Xi'an Jiaotong-Liverpool University--the two Chinese campuses established respectively by the University of Nottingham and the University of Liverpool. They represent successful models of globalization of higher education in China; however their rationale, strategies, curricula,…

Mössbauer studies of hemoglobin in erythrocytes exposed to neutron radiation

NASA Astrophysics Data System (ADS)

Niemiec, Katarzyna; Kaczmarska, Magdalena; Buczkowski, Mateusz; Fornal, Maria; Pohorecki, Władysław; Matlak, Krzysztof; Korecki, Józef; Grodzicki, Tomasz; Burda, Kvetoslava

2012-03-01

We studied radiation effects on the stability of various states of hemoglobin (Hb) in red blood cells (RBC) irradiated with a very low dose of neutron rays, 50 μGy. We investigated RBCs isolated from blood of healthy donors. Mössbauer spectroscopy was applied to monitor different forms of Hb. Our results show, for the first time, that oxyhemoglobin (OxyHb) and deoxyhemoglobin (DeoxyHb) are two Hb forms sensitive to such a low neutron radiation. Both Hbs change into a new Hb form (Hbirr). Additionally, OxyHb transfers into HbOH/H2O, which under our experimental conditions is resistant to the action of neutron rays.

Neutron-fragment and Neutron-neutron Correlations in Low-energy Fission

NASA Astrophysics Data System (ADS)

Lestone, J. P.

2016-01-01

A computational method has been developed to simulate neutron emission from thermal-neutron induced fission of 235U and from spontaneous fission of 252Cf. Measured pre-emission mass-yield curves, average total kinetic energies and their variances, both as functions of mass split, are used to obtain a representation of the distribution of fragment velocities. Measured average neutron multiplicities as a function of mass split and their dependence on total kinetic energy are used. Simulations can be made to reproduce measured factorial moments of neutron-multiplicity distributions with only minor empirical adjustments to some experimental inputs. The neutron-emission spectra in the rest-frame of the fragments are highly constrained by ENDF/B-VII.1 prompt-fission neutron-spectra evaluations. The n-f correlation measurements of Vorobyev et al. (2010) are consistent with predictions where all neutrons are assumed to be evaporated isotropically from the rest frame of fully accelerated fragments. Measured n-f and n-n correlations of others are a little weaker than the predictions presented here. These weaker correlations could be used to infer a weak scission-neutron source. However, the effect of neutron scattering on the experimental results must be studied in detail before moving away from a null hypothesis that all neutrons are evaporated from the fragments.

High-dose neutron detector project update

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

Menlove, Howard Olsen; Henzlova, Daniela

These are the slides for a progress review meeting by the sponsor. This is an update on the high-dose neutron detector project. In summary, improvements in both boron coating and signal amplification have been achieved; improved boron coating materials and procedures have increased efficiency by ~ 30-40% without the corresponding increase in the detector plate area; low dead-time via thin cell design (~ 4 mm gas gaps) and fast amplifiers; prototype PDT 8” pod has been received and testing is in progress; significant improvements in efficiency and stability have been verified; use commercial PDT 10B design and fabrication to obtainmore » a faster path from the research to practical high-dose neutron detector.« less

Neutron diffraction study, magnetic properties and thermal stability of YMn 2D 6 synthesized under high deuterium pressure

NASA Astrophysics Data System (ADS)

Paul-Boncour, V.; Filipek, S. M.; Dorogova, M.; Bourée, F.; André, G.; Marchuk, I.; Percheron-Guégan, A.; Liu, R. S.

2005-01-01

A new phase YMn 2D 6 was synthesized by submitting YMn 2 to 1.7 kbar deuterium pressure at 473 K. According to X-ray and neutron powder diffraction experiments, YMn 2D 6 crystallizes in the Fm3¯m space group with a=6.709(1) Å at 300 K. The Y and half of the Mn atoms occupy statistically the 8 c site whereas the other Mn atoms are located in 4 a site and surrounded by 6 D atoms (24 e). This corresponds to a K 2PtCl 6-type structure with a partially disordered substructure which can be written as [YMn]MnH 6. No ordered magnetic moment is observed in the NPD patterns and the magnetization measurements display a paramagnetic behavior. The study of the thermal stability by Differential Scanning Calorimetry and XRD experiments indicates that this phase decomposes in YD 2 and Mn at 625 K, and is more stable than YMn 2H 4.5.

Calculation of the {pi}{sup +}{Sigma}{sup +} and {pi}{sup +}{Xi}{sup 0} Scattering Lengths in Lattice QCD

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

Torok, Aaron

The {pi}{sup +}{Sigma}{sup +} and {pi}{sup +}{Xi}{sup 0} scattering lengths were calculated in mixed-action Lattice QCD with domain-wall valence quarks on the asqtad-improved coarse MILC configurations at four light-quark masses, and at two light-quark masses on the fine MILC configurations. Heavy Baryon Chiral Perturbation Theory with two and three flavors of light quarks was used to perform the chiral extrapolations. To NNLO in the three-flavor chiral expansion, the kaon-baryon processes that were investigated show no signs of convergence. Using the two-flavor chiral expansion for extrapolation, the pion-hyperon scattering lengths are found to be a{sub {pi}}{sup +}{sub {Sigma}}{sup +} = -0.197{+-}0.017more » fm, and a{sub {pi}}{sup +}{sub {Xi}}{sup 0} = -0.098{+-}0.017 fm, where the comprehensive error includes statistical and systematic uncertainties.« less

Structural characterization of the phospholipid stabilizer layer at the solid-liquid interface of dispersed triglyceride nanocrystals with small-angle x-ray and neutron scattering

NASA Astrophysics Data System (ADS)

Schmiele, Martin; Schindler, Torben; Unruh, Tobias; Busch, Sebastian; Morhenn, Humphrey; Westermann, Martin; Steiniger, Frank; Radulescu, Aurel; Lindner, Peter; Schweins, Ralf; Boesecke, Peter

2013-06-01

Dispersions of crystalline nanoparticles with at least one sufficiently large unit cell dimension can give rise to Bragg reflections in the small-angle scattering range. If the nanocrystals possess only a small number of unit cells along these particular crystallographic directions, the corresponding Bragg reflections will be broadened. In a previous study of phospholipid stabilized dispersions of β-tripalmitin platelets [Unruh, J. Appl. Crystallogr.JACGAR0021-889810.1107/S0021889807044378 40, 1008 (2007)], the x-ray powder pattern simulation analysis (XPPSA) was developed. The XPPSA method facilitates the interpretation of the rather complicated small-angle x-ray scattering (SAXS) curves of such dispersions of nanocrystals. The XPPSA method yields the distribution function of the platelet thicknesses and facilitates a structural characterization of the phospholipid stabilizer layer at the solid-liquid interface between the nanocrystals and the dispersion medium from the shape of the broadened 001 Bragg reflection. In this contribution an improved and extended version of the XPPSA method is presented. The SAXS and small-angle neutron scattering patterns of dilute phospholipid stabilized tripalmitin dispersions can be reproduced on the basis of a consistent simulation model for the particles and their phospholipid stabilizer layer on an absolute scale. The results indicate a surprisingly flat arrangement of the phospholipid molecules in the stabilizer layer with a total thickness of only 12 Å. The stabilizer layer can be modeled by an inner shell for the fatty acid chains and an outer shell including the head groups and additional water. The experiments support a dense packing of the phospholipid molecules on the nanocrystal surfaces rather than isolated phospholipid domains.

Role of high-spin hyperon resonances in the reaction of {gamma}p{yields}K{sup +}K{sup +}{Xi}{sup -}

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

Man, J. Ka Shing; Oh, Yongseok; Excited Baryon Analysis Center, Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606

The recent data taken by the CLAS Collaboration at the Thomas Jefferson National Accelerator Facility for the reaction of {gamma}p{yields}K{sup +}K{sup +}{Xi}{sup -} are reanalyzed within a relativistic meson-exchange model of hadronic interactions. The present model is an extension of the one developed in an earlier work by Nakayama, Oh, and Haberzettl [Phys. Rev. C 74, 035205 (2006)]. In particular, the role of the spin-5/2 and -7/2 hyperon resonances, which were not included in the previous model, is investigated in the present study. It is shown that the contribution of the {Sigma}(2030) hyperon having spin-7/2 and positive parity has amore » key role to bring the model predictions into a fair agreement with the measured data for the K{sup +}{Xi}{sup -} invariant mass distribution.« less

Strange hadron (neutral kaon(short), lambda baryon and Xi baryon) production in deuteron+gold collisions at center of mass energy = 200 GeV at RHIC

NASA Astrophysics Data System (ADS)

Jiang, Hai

The study of identified particles from deuteron(d)+gold(Au) collisions provide a crucial reference to investigate nuclear effects observed in Au+Au collisions where a thermalized partonic state - Quark Gluon Plasma (QGP) - is thought to have been created. The measurements of transverse mass (mT) and momentum (pT) spectra at mid-rapidity (| y| < 1) for the identified strange hadrons: K0S , Λ + Λ and xi- + xi+ from d+Au collisions are presented. The measured pT covers 0.4 < p T < 6.0 GeV/c for K0S and Λ + Λ and 0.6 < pT < 5.0 GeV/c for xi- + xi+. These particles were reconstructed from the topological characteristics of their weak decays in the STAR Time Projection Chamber (TPC). The mT spectra of these particles are well described by a double exponential function which can be understood by two component models: soft (thermal) hadron production at low mT and hard hadron production at high mT. The integrated yields (dN/dy) and mean pT (< pT >) of these particles are calculated from the fit functions for different centralities. The dN/dy normalized to the number of participants (Npart) increase with Npart. The Λ(Λ ) dN/dy values at the mid-rapidity and forward rapidity regions agree with the EPOS model calculations. The measured Λ/ K0S ratios show the greatest baryon enhancement at pT ˜ 2 GeV/c in d+Au collisions. The strangeness enhancement going from d+Au to Au+Au collisions grows with the number of strange quark in a hadron. The magnitude of the enhancement is in the same order as the SPS measurement. The nuclear modification factors RCP normalized to binary collisions indicate that the Cronin effect in d+Au collisions has a distinct particle type dependence. The RCP ratios show a distinct baryon versus meson dependence: the RCP for xi- + xi+ follows that for Λ + Λ while the R CP for the φ is close to that for the K0S . The mechanism based on initial hadron or parton multiple scattering is not sufficient to explain this particle type dependence

Physicsdesign point for a 1MW fusion neutron source

NASA Astrophysics Data System (ADS)

Woodruff, Simon; Melnik, Paul; Sieck, Paul; Stuber, James; Romero-Talamas, Carlos; O'Bryan, John; Miller, Ronald

2016-10-01

We are developing a design point for a spheromak experiment heated by adiabatic compression for use as a compact neutron source. We utilize the CORSICA and NIMROD MHD codes as well as analytic modeling to assess a concept with target parameters R0 =0.5m, Rf =0.17m, T0 =1keV, Tf =8keV, n0 =2e20m-3 and nf = 5e21m-3, with radial convergence of C =R0/Rf =3. We present results from CORSICA showing the placement of coils and passive structure to ensure stability during compression. We specify target parameters for the compression in terms of plasma beta, formation efficiency and energy confinement. We present results simulations of magnetic compression using the NIMROD code to examine the role of rotation on the stability and confinement of the spheromak as it is compressed. Supported by DARPA Grant N66001-14-1-4044 and IAEA CRP on Compact Fusion Neutron Sources.

Molecular and genetic characterization of the Ry adg locus on chromosome XI from Andigena potatoes conferring extreme resistance to potato virus Y.

PubMed

Herrera, María Del Rosario; Vidalon, Laura Jara; Montenegro, Juan D; Riccio, Cinzia; Guzman, Frank; Bartolini, Ida; Ghislain, Marc

2018-05-31

We have elucidated the Andigena origin of the potato Ry adg gene on chromosome XI of CIP breeding lines and developed two marker assays to facilitate its introgression in potato by marker-assisted selection. Potato virus Y (PVY) is causing yield and quality losses forcing farmers to renew periodically their seeds from clean stocks. Two loci for extreme resistance to PVY, one on chromosome XI and the other on XII, have been identified and used in breeding. The latter corresponds to a well-known source of resistance (Solanum stoloniferum), whereas the one on chromosome XI was reported from S. stoloniferum and S. tuberosum group Andigena as well. To elucidate its taxonomic origin in our breeding lines, we analyzed the nucleotide sequences of tightly linked markers (M45, M6) and screened 251 landraces of S. tuberosum group Andigena for the presence of this gene. Our results indicate that the PVY resistance allele on chromosome XI in our breeding lines originated from S. tuberosum group Andigena. We have developed two marker assays to accelerate the introgression of Ry adg gene into breeding lines by marker-assisted selection (MAS). First, we have multiplexed RYSC3, M6 and M45 DNA markers flanking the Ry adg gene and validated it on potato varieties with known presence/absence of the Ry adg gene and a progeny of 6,521 individuals. Secondly, we developed an allele-dosage assay particularly useful to identify multiplex Ry adg progenitors. The assay based on high-resolution melting analysis at the M6 marker confirmed Ry adg plex level as nulliplex, simplex and duplex progenitors and few triplex progenies. These marker assays have been validated and can be used to facilitate MAS in potato breeding.

Rhodium self-powered neutron detector as a suitable on-line thermal neutron flux monitor in BNCT treatments

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

Miller, Marcelo E.; Sztejnberg, Manuel L.; Gonzalez, Sara J.

2011-12-15

Purpose: A rhodium self-powered neutron detector (Rh SPND) has been specifically developed by the Comision Nacional de Energia Atomica (CNEA) of Argentina to measure locally and in real time thermal neutron fluxes in patients treated with boron neutron capture therapy (BNCT). In this work, the thermal and epithermal neutron response of the Rh SPND was evaluated by studying the detector response to two different reactor spectra. In addition, during clinical trials of the BNCT Project of the CNEA, on-line neutron flux measurements using the specially designed detector were assessed. Methods: The first calibration of the detector was done with themore » well-thermalized neutron spectrum of the CNEA RA-3 reactor thermal column. For this purpose, the reactor spectrum was approximated by a Maxwell-Boltzmann distribution in the thermal energy range. The second calibration was done at different positions along the central axis of a water-filled cylindrical phantom, placed in the mixed thermal-epithermal neutron beam of CNEA RA-6 reactor. In this latter case, the RA-6 neutron spectrum had been well characterized by both calculation and measurement, and it presented some marked differences with the ideal spectrum considered for SPND calibrations at RA-3. In addition, the RA-6 neutron spectrum varied with depth in the water phantom and thus the percentage of the epithermal contribution to the total neutron flux changed at each measurement location. Local (one point-position) and global (several points-positions) and thermal and mixed-field thermal neutron sensitivities were determined from these measurements. Thermal neutron flux was also measured during BNCT clinical trials within the irradiation fields incident on the patients. In order to achieve this, the detector was placed on patient's skin at dosimetric reference points for each one of the fields. System stability was adequate for this kind of measurement. Results: Local mixed-field thermal neutron sensitivities and

Rhodium self-powered neutron detector as a suitable on-line thermal neutron flux monitor in BNCT treatments.

PubMed

Miller, Marcelo E; Sztejnberg, Manuel L; González, Sara J; Thorp, Silvia I; Longhino, Juan M; Estryk, Guillermo

2011-12-01

A rhodium self-powered neutron detector (Rh SPND) has been specifically developed by the Comisión Nacional de Energía Atómica (CNEA) of Argentina to measure locally and in real time thermal neutron fluxes in patients treated with boron neutron capture therapy (BNCT). In this work, the thermal and epithermal neutron response of the Rh SPND was evaluated by studying the detector response to two different reactor spectra. In addition, during clinical trials of the BNCT Project of the CNEA, on-line neutron flux measurements using the specially designed detector were assessed. The first calibration of the detector was done with the well-thermalized neutron spectrum of the CNEA RA-3 reactor thermal column. For this purpose, the reactor spectrum was approximated by a Maxwell-Boltzmann distribution in the thermal energy range. The second calibration was done at different positions along the central axis of a water-filled cylindrical phantom, placed in the mixed thermal-epithermal neutron beam of CNEA RA-6 reactor. In this latter case, the RA-6 neutron spectrum had been well characterized by both calculation and measurement, and it presented some marked differences with the ideal spectrum considered for SPND calibrations at RA-3. In addition, the RA-6 neutron spectrum varied with depth in the water phantom and thus the percentage of the epithermal contribution to the total neutron flux changed at each measurement location. Local (one point-position) and global (several points-positions) and thermal and mixed-field thermal neutron sensitivities were determined from these measurements. Thermal neutron flux was also measured during BNCT clinical trials within the irradiation fields incident on the patients. In order to achieve this, the detector was placed on patient's skin at dosimetric reference points for each one of the fields. System stability was adequate for this kind of measurement. Local mixed-field thermal neutron sensitivities and global thermal and mixed

Beta-Delayed Neutron Spectroscopy of 72Co with VANDLE

NASA Astrophysics Data System (ADS)

Keeler, Andrew; Grzywacz, Robert; King, Thomas; Taylor, Steven; Paulauskas, Stanley; Zachary, Christopher; Vandle Collaboration

2017-09-01

Measurements of simple, closed-shell isotopes far from stability provide important benchmarks for nuclear models and are a key constraint in r-process calculations. In particular, r-process models are sensitive to beta decay lifetimes and branching ratios of these neutron-rich isotopes. In this experiment, the Versatile Array of Neutron Detectors at Low Energy (VANDLE) was used to observe decays of nuclei produced by the fragmentation of 82Se at the National Superconducting Cyclotron Laboratory (NSCL). The neutron and gamma emissions of 72Co were measured to map the beta strength distribution (S_beta) above the neutron separation energy and infer the size of the Z = 28 shell gap in the 78Ni region. An implantation detector made of a radiation-hardened, inorganic scintillator was used to correlate implanted ions with beta decays as well as provide a start signal for the neutron Time of Flight measurement. Funded by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Award No. DE-NA0002132 and by the Office of Nuclear Physics, U.S. Department of Energy under Awards No. DE-FG02-96ER40983 (UTK).

Observation of the {omega}{sub b}{sup -} baryon and measurement of the properties of the {xi}{sub b}{sup -} and {omega}{sub b}{sup -} baryons

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

Aaltonen, T.; Maki, T.; Mehtala, P.

We report the observation of the bottom, doubly-strange baryon {omega}{sub b}{sup -} through the decay chain {omega}{sub b}{sup -}{yields}J/{psi}{omega}{sup -}, where J/{psi}{yields}{mu}{sup +}{mu}{sup -}, {omega}{sup -}{yields}{lambda}K{sup -}, and {lambda}{yields}p{pi}{sup -}, using 4.2 fb{sup -1} of data from pp collisions at {radical}(s)=1.96 TeV, and recorded with the Collider Detector at Fermilab. A signal is observed whose probability of arising from a background fluctuation is 4.0x10{sup -8}, or 5.5 Gaussian standard deviations. The {omega}{sub b}{sup -} mass is measured to be 6054.4{+-}6.8(stat){+-}0.9(syst) MeV/c{sup 2}. The lifetime of the {omega}{sub b}{sup -} baryon is measured to be 1.13{sub -0.40}{sup +0.53}(stat){+-}0.02(syst) ps. In addition,more » for the {xi}{sub b}{sup -} baryon we measure a mass of 5790.9{+-}2.6(stat){+-}0.8(syst) MeV/c{sup 2} and a lifetime of 1.56{sub -0.25}{sup +0.27}(stat){+-}0.02(syst) ps. Under the assumption that the {xi}{sub b}{sup -} and {omega}{sub b}{sup -} are produced with similar kinematic distributions to the {lambda}{sub b}{sup 0} baryon, we find ({sigma}({xi}{sub b}{sup -})B({xi}{sub b}{sup -}{yields}J/{psi}{xi}{sup -})/{sigma}({lambda}{sub b}{sup 0})B({lambda}{sub b}{sup 0}{yields}J/{psi}{lambda}))=0.167{sub -0.025}{sup +0.037}(stat){+-}0.012(syst) and ({sigma}({omega}{sub b}{sup -})B({omega}{sub b}{sup -}{yields}J/{psi}{omega}{sup -})/{sigma}({lambda}{sub b}{sup 0})B({lambda}{sub b}{sup 0}{yields}J/{psi}{lambda}))=0.045{sub -0.012}{sup +0.017}(stat){+-} 0.004(syst) for baryons produced with transverse momentum in the range of 6-20 GeV/c.« less

Impact on air quality of measures to reduce CO2 emissions from road traffic in Basel, Rotterdam, Xi'an and Suzhou

NASA Astrophysics Data System (ADS)

Keuken, M. P.; Jonkers, S.; Verhagen, H. L. M.; Perez, L.; Trüeb, S.; Okkerse, W.-J.; Liu, J.; Pan, X. C.; Zheng, L.; Wang, H.; Xu, R.; Sabel, C. E.

2014-12-01

Two traffic scenarios to reduce CO2 emissions from road traffic in two European cities (Basel and Rotterdam) and two Chinese cities (Xi'an and Suzhou) were evaluated in terms of their impact on air quality. The two scenarios, one modelling a reduction of private vehicle kilometres driven by 10% on urban streets and the other modelling the introduction of 50% electric-powered private vehicle kilometres on urban streets, were both compared to a scenario following “business-as-usual”: 2020-BAU. The annual average concentrations of NO2, PM2.5, PM10 and elemental carbon (EC) were modelled separately in busy street canyons, near urban motorways and in the remainder of the urban area. It was concluded that traffic-related CO2 emissions in 2020-BAU could be expected to remain at the levels of 2010 in Basel and Rotterdam, while in Xi'an and Suzhou to increase 30-50% due to growth in the traffic volume. Traffic-related CO2 emissions may be reduced by up to 5% and 25%, respectively using the first and second scenarios. Air pollution in the Chinese cities is a factor 3 to 5 higher than in the European cities in 2010 and 2020-BAU. The impact of both CO2 reduction scenarios on air quality in 2020-BAU is limited. In Europe, due to implementation of stringent emission standards in all sectors, air quality is expected to improve at both the urban background and near busy road traffic. In China, the regional background is expected to improve for EC, stabilize for PM2.5 and PM10, and decrease for NO2. The urban background follows this regional trend, while near busy road traffic, air pollution will remain elevated due to the considerable growth in traffic volume. A major constraint for modelling air quality in China is access to the input data required and lack of measurements at ground level for validation.

Microscopic description of quadrupole collectivity in neutron-rich nuclei across the N = 126 shell closure

NASA Astrophysics Data System (ADS)

Rodríguez-Guzmán, R.; Robledo, L. M.; Sharma, M. M.

2015-06-01

The quadrupole collectivity in Nd, Sm, Gd, Dy, Er, Yb, Hf and W nuclei with neutron numbers 122 ≤ N ≤ 156 is studied, both at the mean field level and beyond, using the Gogny energy density functional. Besides the robustness of the N = 126 neutron shell closure, it is shown that the onset of static deformations in those isotopic chains with increasing neutron number leads to an enhanced stability and further extends the corresponding two-neutron drip lines far beyond what could be expected from spherical calculations. Independence of the mean-field predictions with respect to the particular version of the Gogny energy density functional employed is demonstrated by comparing results based on the D1S and D1M parameter sets. Correlations beyond mean field are taken into account in the framework of the angular momentum projected generator coordinate method calculation. It is shown that N = 126 remains a robust neutron magic number when dynamical effects are included. The analysis of the collective wave functions, average deformations and excitation energies indicate that, with increasing neutron number, the zero-point quantum corrections lead to dominant prolate configurations in the 0{1/+}, 0{2/+}, 2{1/+} and 2{2/+} states of the studied nuclei. Moreover, those dynamical deformation effects provide an enhanced stability that further supports the mean-field predictions, corroborating a shift of the r-process path to higher neutron numbers. Beyond mean-field calculations provide a smaller shell gap at N = 126 than the mean-field one in good agreement with previous theoretical studies. However, the shell gap still remains strong enough in the two-neutron drip lines.

LighSail Students Testing - ELaNa XI

NASA Image and Video Library

2014-09-23

Students Alex Diaz and Riki Munakata of California Polytechnic State University testing the LightSail CubeSat. LightSail is a citizen-funded technology demonstration mission sponsored by the Planetary Society using solar propulsion for CubeSats. The spacecraft is designed to “sail” on the energy of solar photons striking the thin, reflective sail material. The first LightSail mission is designed to test the spacecraft’s critical systems, including the sequence to autonomously deploy a Mylar solar sail with an area of 32 square meters (344 square feet). The Planetary Society is planning a second, full solar sailing demonstration flight for 2016. Light is made of packets of energy called photons. While photons have no mass, they have energy and momentum. Solar sails use this momentum as a method of propulsion, creating flight by light. LightSail’s solar sail is packaged into a three-unit CubeSat about the size of a loaf of bread. Launched by NASA’s CubeSat Launch Initiative on the ELaNa XI mission as an auxiliary payload aboard the U.S. Air Force X-37B space plane mission on May 20, 2015.

An isoform of myosin XI is responsible for the translocation of endoplasmic reticulum in tobacco cultured BY-2 cells.

PubMed

Yokota, Etsuo; Ueda, Shunpei; Tamura, Kentaro; Orii, Hidefumi; Uchi, Satoko; Sonobe, Seiji; Hara-Nishimura, Ikuko; Shimmen, Teruo

2009-01-01

The involvement of myosin XI in generating the motive force for cytoplasmic streaming in plant cells is becoming evident. For a comprehensive understanding of the physiological roles of myosin XI isoforms, it is necessary to elucidate the properties and functions of each isoform individually. In tobacco cultured BY-2 cells, two types of myosins, one composed of 175 kDa heavy chain (175 kDa myosin) and the other of 170 kDa heavy chain (170 kDa myosin), have been identified biochemically and immunocytochemically. From sequence analyses of cDNA clones encoding heavy chains of 175 kDa and 170 kDa myosin, both myosins have been classified as myosin XI. Immunocytochemical studies using a polyclonal antibody against purified 175 kDa myosin heavy chain showed that the 175 kDa myosin is distributed throughout the cytoplasm as fine dots in interphase BY-2 cells. During mitosis, some parts of 175 kDa myosin were found to accumulate in the pre-prophase band (PPB), spindle, the equatorial plane of a phragmoplast and on the circumference of daughter nuclei. In transgenic BY-2 cells, in which an endoplasmic reticulum (ER)-specific retention signal, HDEL, tagged with green fluorescent protein (GFP) was stably expressed, ER showed a similar behaviour to that of 175 kDa myosin. Furthermore, this myosin was co-fractionated with GFP-ER by sucrose density gradient centrifugation. From these findings, it was suggested that the 175 kDa myosin is a molecular motor responsible for translocating ER in BY-2 cells.

PyCMSXiO: an external interface to script treatment plans for the Elekta® CMS XiO treatment planning system

NASA Astrophysics Data System (ADS)

Xing, Aitang; Arumugam, Sankar; Holloway, Lois; Goozee, Gary

2014-03-01

Scripting in radiotherapy treatment planning systems not only simplifies routine planning tasks but can also be used for clinical research. Treatment planning scripting can only be utilized in a system that has a built-in scripting interface. Among the commercially available treatment planning systems, Pinnacle (Philips) and Raystation (Raysearch Lab.) have inherent scripting functionality. CMS XiO (Elekta) is a widely used treatment planning system in radiotherapy centres around the world, but it does not have an interface that allows the user to script radiotherapy plans. In this study an external scripting interface, PyCMSXiO, was developed for XiO using the Python programming language. The interface was implemented as a python package/library using a modern object-oriented programming methodology. The package was organized as a hierarchy of different classes (objects). Each class (object) corresponds to a plan object such as the beam of a clinical radiotherapy plan. The interface of classes was implemented as object functions. Scripting in XiO using PyCMSXiO is comparable with Pinnacle scripting. This scripting package has been used in several research projects including commissioning of a beam model, independent three-dimensional dose verification for IMRT plans and a setup-uncertainty study. Ease of use and high-level functions provided in the package achieve a useful research tool. It was released as an open-source tool that may benefit the medical physics community.

First neutron spectroscopy measurements with a pixelated diamond detector at JET

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

Muraro, A., E-mail: muraro@ifp.cnr.it; Giacomelli, L.; Grosso, G.

2016-11-15

A prototype Single crystal Diamond Detector (SDD) was installed at the Joint European Torus (JET) in 2013 along an oblique line of sight and demonstrated the possibility to carry out neutron spectroscopy measurements with good energy resolution and detector stability in discharges heated by neutral beam injection and radio-frequency waves. Starting from these positive results, within the Vertical Neutron Spectrometer project of the Joint European Torus, we have developed a pixelated instrument consisting of a matrix of 12 independent SDDs, called the Diamond Vertical Neutron Spectrometer (DVNS), which boosts the detection efficiency of a single SDD by an order ofmore » magnitude. In this paper we describe the main features of the DVNS, including the detector design, energy resolution, and data acquisition system for on-line processing. Preliminary spectroscopy measurements of 2.5 MeV neutrons from the present deuterium plasma at JET are finally presented.« less

First neutron spectroscopy measurements with a pixelated diamond detector at JET.

PubMed

Muraro, A; Giacomelli, L; Nocente, M; Rebai, M; Rigamonti, D; Belli, F; Calvani, P; Figueiredo, J; Girolami, M; Gorini, G; Grosso, G; Murari, A; Popovichev, S; Trucchi, D M; Tardocchi, M

2016-11-01

A prototype Single crystal Diamond Detector (SDD) was installed at the Joint European Torus (JET) in 2013 along an oblique line of sight and demonstrated the possibility to carry out neutron spectroscopy measurements with good energy resolution and detector stability in discharges heated by neutral beam injection and radio-frequency waves. Starting from these positive results, within the Vertical Neutron Spectrometer project of the Joint European Torus, we have developed a pixelated instrument consisting of a matrix of 12 independent SDDs, called the Diamond Vertical Neutron Spectrometer (DVNS), which boosts the detection efficiency of a single SDD by an order of magnitude. In this paper we describe the main features of the DVNS, including the detector design, energy resolution, and data acquisition system for on-line processing. Preliminary spectroscopy measurements of 2.5 MeV neutrons from the present deuterium plasma at JET are finally presented.

Structural responses of metallic glasses under neutron irradiation.

PubMed

Yang, L; Li, H Y; Wang, P W; Wu, S Y; Guo, G Q; Liao, B; Guo, Q L; Fan, X Q; Huang, P; Lou, H B; Guo, F M; Zeng, Q S; Sun, T; Ren, Y; Chen, L Y

2017-12-01

Seeking nuclear materials that possess a high resistance to particle irradiation damage is a long-standing issue. Permanent defects, induced by irradiation, are primary structural changes, the accumulation of which will lead to structural damage and performance degradation in crystalline materials served in nuclear plants. In this work, structural responses of neutron irradiation in metallic glasses (MGs) have been investigated by making a series of experimental measurements, coupled with simulations in ZrCu amorphous alloys. It is found that, compared with crystalline alloys, MGs have some specific structural responses to neutron irradiation. Although neutron irradiation can induce transient vacancy-like defects in MGs, they are fully annihilated after structural relaxation by rearrangement of free volumes. In addition, the rearrangement of free volumes depends strongly on constituent elements. In particular, the change in free volumes occurs around the Zr atoms, rather than the Cu centers. This implies that there is a feasible strategy for identifying glassy materials with high structural stability against neutron irradiation by tailoring the microstructures, the systems, or the compositions in alloys. This work will shed light on the development of materials with high irradiation resistance.

Breit–Pauli atomic structure calculations for Fe XI

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

Aggarwal, Sunny, E-mail: sunny.du87@gmail.com; Singh, Jagjit; Mohan, Man

Energy levels, oscillator strengths, and transition probabilities are calculated for the lowest-lying 165 energy levels of Fe XI using configuration-interaction wavefunctions. The calculations include all the major correlation effects. Relativistic effects are included in the Breit–Pauli approximation by adding mass-correction, Darwin, and spin–orbit interaction terms to the non-relativistic Hamiltonian. For comparison with the calculated ab initio energy levels, we have also calculated the energy levels by using the fully relativistic multiconfiguration Dirac–Fock method. The calculated results are in close agreement with the National Institute of Standards and Technology compilation and other available results. New results are predicted for many ofmore » the levels belonging to the 3s3p{sup 4}3d and 3s3p{sup 3}3d{sup 2} configurations, which are very important in astrophysics, relevant, for example, to the recent observations by the Hinode spacecraft. We expect that our extensive calculations will be useful to experimentalists in identifying the fine structure levels in their future work.« less

Coronal Abundances In Xi Boo A, Abundances in the Corona of FK Aqr and the Origin of Cosmic Ray

NASA Technical Reports Server (NTRS)

Drake, Jeremy; Oliversen, Ronald J. (Technical Monitor)

2002-01-01

Both Xi Boo A and FK Agr observations have been acquired, reduced and analysed. The results of the Xi Boo A study were published in ApJ (Drake, J.J., Kashyap, V., 2001, Up, 547, 428). Work is ongoing to determine the coronet metallicity of FK Aqr based on EUVE spectra and DO photometer data, using the techniques developed in the Drake & Kashyap paper. Preliminary synthetic spectra for FK Aqr have been developed, and further work to heap define the hot plasma emission measure distribution is underway. Progress on spectral analysis has been hampered following the post-doctoral scientist, Vinay Kashyap, taking up new position. A suitable replacement has been difficult to find, but new hire is expected shortly. However, good progress has been made on analysis of DO photometric variations in FK Age, with a publication now ready (Kashyap, V., Drake, J.J., Guedel, M., Audard, M.) for submission to a mainstream astrophysical journal.

Analysis of the Conformally Flat Approximation for Binary Neutron Star Initial Conditions

DOE PAGES

Suh, In-Saeng; Mathews, Grant J.; Haywood, J. Reese; ...

2017-01-09

The spatially conformally flat approximation (CFA) is a viable method to deduce initial conditions for the subsequent evolution of binary neutron stars employing the full Einstein equations. Here in this paper, we analyze the viability of the CFA for the general relativistic hydrodynamic initial conditions of binary neutron stars. We illustrate the stability of the conformally flat condition on the hydrodynamics by numerically evolving ~100 quasicircular orbits. We illustrate the use of this approximation for orbiting neutron stars in the quasicircular orbit approximation to demonstrate the equation of state dependence of these initial conditions and how they might affect themore » emergent gravitational wave frequency as the stars approach the innermost stable circular orbit.« less

FOREWORD: Neutron metrology Neutron metrology

NASA Astrophysics Data System (ADS)

Thomas, David J.; Nolte, Ralf; Gressier, Vincent

2011-12-01

The International Committee for Weights and Measures (CIPM) has consultative committees covering various areas of metrology. The Consultative Committee for Ionizing Radiation (CCRI) differs from the others in having three sections: Section (I) deals with radiation dosimetry, Section (II) with radionuclide metrology and Section (III) with neutron metrology. In 2003 a proposal was made to publish special issues of Metrologia covering the work of the three Sections. Section (II) was the first to complete their task, and their special issue was published in 2007, volume 44(4). This was followed in 2009 by the special issue on radiation dosimetry, volume 46(2). The present issue, volume 48(6), completes the trilogy and attempts to explain neutron metrology, the youngest of the three disciplines, the neutron only having been discovered in 1932, to a wider audience and to highlight the relevance and importance of this field. When originally approached with the idea of this special issue, Section (III) immediately saw the value of a publication specifically on neutron metrology. It is a topic area where papers tend to be scattered throughout the literature in journals covering, for example, nuclear instrumentation, radiation protection or radiation measurements in general. Review articles tend to be few. People new to the field often ask for an introduction to the various topics. There are some excellent older textbooks, but these are now becoming obsolete. More experienced workers in specific areas of neutron metrology can find it difficult to know the latest position in related areas. The papers in this issue attempt, without presenting a purely historical outline, to describe the field in a sufficiently logical way to provide the novice with a clear introduction, while being sufficiently up-to-date to provide the more experienced reader with the latest scientific developments in the different topic areas. Neutron radiation fields obviously occur throughout the nuclear

Optimisation of the manufacturing process of tritide and deuteride targets used for neutron production

NASA Astrophysics Data System (ADS)

Monnin, Carole; Bach, Pierre; Tulle, Pierre Alain; van Rompay, Marc; Ballanger, Anne

2002-03-01

As a neutron tube manufacturer, SODERN is now in charge of manufacturing tritium targets for accelerators, in cooperation with CEA/DAM/DTMN in Valduc. Specific deuterium and tritium targets are manufactured on request, according to the requirements of the users, starting from titanium targets on copper substrates, and going to more sophisticated devices. The range of possible uses is wide, including thin targets for neutron calibration, thick targets with controlled loading of deuterium and tritium, rotating targets or large size rotating targets for higher lifetimes. The activity of the targets ranges from 3.7×10 10 to 3.7×10 13 Bq (1-1000 Ci), the diameter being up to 30 cm. Sodern and the CEA/Valduc centre have developed different technologies for tritium target manufacture, allowing the selection of the best configuration for each kind of use. In order to optimize the production of high energy neutrons, the performance of tritide and deuteride titanium targets made by different processes has been studied experimentally by bombardment with 120 and 350 kV deuterons provided by electrostatic accelerators. It is then possible to optimize either neutron output or lifetime and stability or thermal behaviour. The importance of the deposit evaporation conditions on the efficiency of neutron emission is clearly demonstrated, as well as the thermomechanical stability of the Ti thin film under deuteron bombardment. The main parameters involved in the target performance are discussed from a thermodynamical approach.

Neutral B-meson mixing from three-flavor lattice QCD: Determination of the SU(3)-breaking ratio \\xi

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

Bazavov, A.; /Brookhaven; Bernard, C.

We study SU(3)-breaking effects in the neutral B{sub d}-{bar B}{sub d} and B{sub s}-{bar B}{sub s} systems with unquenched N{sub t}=2+1 lattice quantum chromodynamics (QCD). We calculate the relevant matrix elements on the MILC collaboration's gauge configurations with asqtad-improved staggered sea quarks. For the valence light-quarks (u, d, and s) we use the asqtad action, while for b quarks we use the Fermilab action. We obtain {xi}=f{sub B{sub s}} {radical}{ovr B{sub B{sub s}}}/f{sub B{sub d}}{radical}{ovr B{sub B{sub d}}}=1.268{+-}0.063. We also present results for the ratio of bag parameters B{sub B{sub s}}/B{sub B{sub d}} and the ratio of Cabibbo-Kobayashi-Maskawa matrix elementsmore » |V{sub td}|/|V{sub ts}|. Although we focus on the calculation of {xi}, the strategy and techniques described here will be employed in future extended studies of the B mixing parameters {Delta}M{sub d,s} and {Delta}{Gamma}{sub d,s} in the standard model and beyond.« less

75 FR 44163 - Implementation of Regulations Required Under Title XI of the Food, Conservation and Energy Act of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-28

... Under Title XI of the Food, Conservation and Energy Act of 2008; Conduct in Violation of the Act AGENCY... Act and provide for a fairer market place. DATES: We will consider comments we receive by November 22... clarify conditions for industry compliance with the P&S Act and provide for a fairer market place. We have...

High-temperature long-lasting stability assessment of a single-crystal diamond detector under high-flux neutron irradiation

NASA Astrophysics Data System (ADS)

Pilotti, R.; Angelone, M.; Marinelli, M.; Milani, E.; Verona-Rinati, G.; Verona, C.; Prestopino, G.; Montereali, R. M.; Vincenti, M. A.; Schooneveld, E. M.; Scherillo, A.; Pietropaolo, A.

2016-11-01

An innovative diamond detector layout is presented that is designed to operate at high temperature under intense neutron and gamma fluxes. It is made of a 500 μm “electronic grade” diamond film with 100 nm thick Ag metal contacts deposited onto each surface of the film by means of thermal evaporation. A 2 μ \\text{m} thick layer of 6LiF has been deposited on top of one of the two Ag contacts to make the detector sensitive to thermal neutrons. The device was tested at the ISIS spallation neutron source (Rutherford Appleton Laboratory, UK) using the INES beam line. The detector was continuously irradiated for 100 hours in vacuum (p = 10-5 \\text{mbar}) , exposed to a neutron flux of about 106 n cm-2 s-1 at a temperature T =150 ^\\circ \\text{C} . The aim of this experiment was to study the time dependence of the diamond detector performance while operating at high temperature under irradiation, providing a first experimental proof of reliable continuous operation for 100 hours at high temperature in a harsh environment.

Glycerol, trehalose and glycerol-trehalose mixture effects on thermal stabilization of OCT

NASA Astrophysics Data System (ADS)

Barreca, D.; Laganà, G.; Magazù, S.; Migliardo, F.; Bellocco, E.

2013-10-01

The stabilization effects of trehalose, glycerol and their mixtures on ornithine carbamoyltransferase catalytic activity has been studied as a function of temperature by complementary techniques. The obtained results show that the kinematic viscosities of trehalose (1.0 M) and protein mixture are higher than the one of glycerol plus protein. Changing the trehalose/glycerol ratio, we notice a decrease of the kinematic viscosity values at almost all the analyzed ratio. In particular, the solution composed of 95% trehalose-5% glycerol shows a peculiar behavior. Moreover the trehalose (1.0 M) solution shows the higher OCT thermal stabilization at 343 K, while all the other solutions show minor effects. The smallest stabilizing effect is revealed for the solution that shows the maximum kinematic viscosity. These results support Inelastic Neutron Scattering (INS) and Quasi Elastic Neutron Scattering (QENS) findings, which pointed out a slowing down of the relaxation and diffusive dynamics in some investigated samples.

Sources and Dynamics of Inorganic Carbon within the Upper Reaches of the Xi River Basin, Southwest China

PubMed Central

Zou, Junyu

2016-01-01

The carbon isotopic composition (δ13C) of dissolved and particulate inorganic carbon (DIC; PIC) was used to compare and analyze the origin, dynamics and evolution of inorganic carbon in two headwater tributaries of the Xi River, Southwest China. Carbonate dissolution and soil CO2 were regarded as the primary sources of DIC on the basis of δ13CDIC values which varied along the Nanpan and Beipan Rivers, from −13.9‰ to 8.1‰. Spatial trends in DIC differed between the two rivers (i.e., the tributaries), in part because factors controlling pCO2, which strongly affected carbonate dissolution, differed between the two river basins. Transport of soil CO2 and organic carbon through hydrologic conduits predominately controlled the levels of pCO2 in the Nanpan River. However, pCO2 along the upper reaches of the Nanpan River also was controlled by the extent of urbanization and industrialization relative to agriculture. DIC concentrations in the highly urbanized upper reaches of the Nanpan River were typical higher than in other carbonate-dominated areas of the upper Xi River. Within the Beipan River, the oxidation of organic carbon is the primary process that maintains pCO2 levels. The pCO2 within the Beipan River was more affected by sulfuric acid from coal industries, inputs from a scenic spot, and groundwater than along the Nanpan River. With regards to PIC, the contents and δ13C values in the Nanpan River were generally lower than those in the Beipan River, indicating that chemical and physical weathering contributes more marine carbonate detritus to the PIC along the Beipan River. The CO2 evasion flux from the Nanpan River was higher than that in the Beipan River, and generally higher than along the middle and lower reaches of the Xi River, demonstrating that the Nanpan River is an important net source of atmospheric CO2 in Southwest China. PMID:27513939

Effect of isospin diffusion on the production of neutron-rich nuclei in multinucleon transfer reactions

NASA Astrophysics Data System (ADS)

Niu, Fei; Chen, Peng-Hui; Guo, Ya-Fei; Ma, Chun-Wang; Feng, Zhao-Qing

2018-03-01

The isospin dissipation dynamics in multinucleon transfer reactions has been investigated within the dinuclear system model. Production cross sections of neutron-rich isotopes around projectile-like and target-like fragments are estimated in collisions of Ni,6458+208Pb and 78.86,91Kr +198Pt near Coulomb barrier energies. The isospin diffusion in the nucleon transfer process is coupled to the dissipation of relative motion energy and angular momentum of colliding system. The available data of projectile-like fragments via multinucleon transfer reactions are nicely reproduced. It is found that the light projectile-like fragments are produced in the neutron-rich region because of the isospin equilibrium in two colliding nuclei. However, the heavy target-like fragments tend to be formed on the neutron-poor side above the β -stability line. The neutron-rich projectiles move the maximal yields of heavy nuclei to the neutron-rich domain and are available for producing the heavy exotic isotopes, in particular around the neutron shell closure of N =126 .

The Los Alamos Neutron Science Center Spallation Neutron Sources

NASA Astrophysics Data System (ADS)

Nowicki, Suzanne F.; Wender, Stephen A.; Mocko, Michael

The Los Alamos Neutron Science Center (LANSCE) provides the scientific community with intense sources of neutrons, which can be used to perform experiments supporting civilian and national security research. These measurements include nuclear physics experiments for the defense program, basic science, and the radiation effect programs. This paper focuses on the radiation effects program, which involves mostly accelerated testing of semiconductor parts. When cosmic rays strike the earth's atmosphere, they cause nuclear reactions with elements in the air and produce a wide range of energetic particles. Because neutrons are uncharged, they can reach aircraft altitudes and sea level. These neutrons are thought to be the most important threat to semiconductor devices and integrated circuits. The best way to determine the failure rate due to these neutrons is to measure the failure rate in a neutron source that has the same spectrum as those produced by cosmic rays. Los Alamos has a high-energy and a low-energy neutron source for semiconductor testing. Both are driven by the 800-MeV proton beam from the LANSCE accelerator. The high-energy neutron source at the Weapons Neutron Research (WNR) facility uses a bare target that is designed to produce fast neutrons with energies from 100 keV to almost 800 MeV. The measured neutron energy distribution from WNR is very similar to that of the cosmic-ray-induced neutrons in the atmosphere. However, the flux provided at the WNR facility is typically 5×107 times more intense than the flux of the cosmic-ray-induced neutrons. This intense neutron flux allows testing at greatly accelerated rates. An irradiation test of less than an hour is equivalent to many years of neutron exposure due to cosmic-ray neutrons. The low-energy neutron source is located at the Lujan Neutron Scattering Center. It is based on a moderated source that provides useful neutrons from subthermal energies to ∼100 keV. The characteristics of these sources, and

Application of nuclear analytical techniques using long-life sealed-tube neutron generators.

PubMed

Bach, P; Cluzeau, S; Lambermont, C

1994-01-01

The new range of sealed-tube neutron generators developed by SODERN appears to be appropriate for the industrial environment. The main characteristics are the high emission stability during the very long lifetime of the tube, flexible pulsed mode capability, safety in operation with no radiation in "off" state, and the easy transportation of equipment. Some applications of the neutron generators, called GENIE, are considered: high-sensitivity measurement of transuranic elements in nuclear waste drums, bulk material analysis for process control, and determination of the airborne pollutants for environmental monitoring.

The Los Alamos Neutron Science Center Spallation Neutron Sources

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

Nowicki, Suzanne F.; Wender, Stephen A.; Mocko, Michael

The Los Alamos Neutron Science Center (LANSCE) provides the scientific community with intense sources of neutrons, which can be used to perform experiments supporting civilian and national security research. These measurements include nuclear physics experiments for the defense program, basic science, and the radiation effect programs. This paper focuses on the radiation effects program, which involves mostly accelerated testing of semiconductor parts. When cosmic rays strike the earth's atmosphere, they cause nuclear reactions with elements in the air and produce a wide range of energetic particles. Because neutrons are uncharged, they can reach aircraft altitudes and sea level. These neutronsmore » are thought to be the most important threat to semiconductor devices and integrated circuits. The best way to determine the failure rate due to these neutrons is to measure the failure rate in a neutron source that has the same spectrum as those produced by cosmic rays. Los Alamos has a high-energy and a low-energy neutron source for semiconductor testing. Both are driven by the 800-MeV proton beam from the LANSCE accelerator. The high-energy neutron source at the Weapons Neutron Research (WNR) facility uses a bare target that is designed to produce fast neutrons with energies from 100 keV to almost 800 MeV. The measured neutron energy distribution from WNR is very similar to that of the cosmic-ray-induced neutrons in the atmosphere. However, the flux provided at the WNR facility is typically 5×107 times more intense than the flux of the cosmic-ray-induced neutrons. This intense neutron flux allows testing at greatly accelerated rates. An irradiation test of less than an hour is equivalent to many years of neutron exposure due to cosmic-ray neutrons. The low-energy neutron source is located at the Lujan Neutron Scattering Center. It is based on a moderated source that provides useful neutrons from subthermal energies to ~100 keV. The characteristics of these sources

The Los Alamos Neutron Science Center Spallation Neutron Sources

DOE PAGES

Nowicki, Suzanne F.; Wender, Stephen A.; Mocko, Michael

2017-10-26

The Los Alamos Neutron Science Center (LANSCE) provides the scientific community with intense sources of neutrons, which can be used to perform experiments supporting civilian and national security research. These measurements include nuclear physics experiments for the defense program, basic science, and the radiation effect programs. This paper focuses on the radiation effects program, which involves mostly accelerated testing of semiconductor parts. When cosmic rays strike the earth's atmosphere, they cause nuclear reactions with elements in the air and produce a wide range of energetic particles. Because neutrons are uncharged, they can reach aircraft altitudes and sea level. These neutronsmore » are thought to be the most important threat to semiconductor devices and integrated circuits. The best way to determine the failure rate due to these neutrons is to measure the failure rate in a neutron source that has the same spectrum as those produced by cosmic rays. Los Alamos has a high-energy and a low-energy neutron source for semiconductor testing. Both are driven by the 800-MeV proton beam from the LANSCE accelerator. The high-energy neutron source at the Weapons Neutron Research (WNR) facility uses a bare target that is designed to produce fast neutrons with energies from 100 keV to almost 800 MeV. The measured neutron energy distribution from WNR is very similar to that of the cosmic-ray-induced neutrons in the atmosphere. However, the flux provided at the WNR facility is typically 5×107 times more intense than the flux of the cosmic-ray-induced neutrons. This intense neutron flux allows testing at greatly accelerated rates. An irradiation test of less than an hour is equivalent to many years of neutron exposure due to cosmic-ray neutrons. The low-energy neutron source is located at the Lujan Neutron Scattering Center. It is based on a moderated source that provides useful neutrons from subthermal energies to ~100 keV. The characteristics of these sources

Neutron range spectrometer

DOEpatents

Manglos, S.H.

1988-03-10

A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. 1 fig.

Designing Mixed Detergent Micelles for Uniform Neutron Contrast

DOE PAGES

Oliver, Ryan C.; Pingali, Sai Venkatesh; Urban, Volker S.

2017-09-29

Micelle-forming detergents provide an amphipathic environment that mimics lipid bilayers and are important tools used to solubilize and stabilize membrane proteins in solution for in vitro structural investigations. Small-angle neutron scattering (SANS) performed at the neutron contrast match point of detergent molecules allows observing the scattering signal from membrane proteins unobstructed by contributions from the detergent. However, we show here that even for a perfectly average-contrast matched detergent there arises significant core-shell scattering from the contrast difference between aliphatic detergent tails and hydrophilic head groups. This residual signal at the average detergent contrast match point interferes with interpreting structural datamore » of membrane proteins. This complication is often made worse by the presence of excess empty (protein-free) micelles. Here, we present an approach for the rational design of mixed micelles containing a deuterated detergent analog, which eliminates neutron contrast between core and shell, and allows the micelle scattering to be fully contrast matched to unambiguously resolve membrane protein structure using solution SANS.« less

Designing Mixed Detergent Micelles for Uniform Neutron Contrast

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

Oliver, Ryan C.; Pingali, Sai Venkatesh; Urban, Volker S.

Micelle-forming detergents provide an amphipathic environment that mimics lipid bilayers and are important tools used to solubilize and stabilize membrane proteins in solution for in vitro structural investigations. Small-angle neutron scattering (SANS) performed at the neutron contrast match point of detergent molecules allows observing the scattering signal from membrane proteins unobstructed by contributions from the detergent. However, we show here that even for a perfectly average-contrast matched detergent there arises significant core-shell scattering from the contrast difference between aliphatic detergent tails and hydrophilic head groups. This residual signal at the average detergent contrast match point interferes with interpreting structural datamore » of membrane proteins. This complication is often made worse by the presence of excess empty (protein-free) micelles. Here, we present an approach for the rational design of mixed micelles containing a deuterated detergent analog, which eliminates neutron contrast between core and shell, and allows the micelle scattering to be fully contrast matched to unambiguously resolve membrane protein structure using solution SANS.« less

Neutronic reactor

DOEpatents

Wende, Charles W. J.; Babcock, Dale F.; Menegus, Robert L.

1983-01-01

A nuclear reactor includes an active portion with fissionable fuel and neutron moderating material surrounded by neutron reflecting material. A control element in the active portion includes a group of movable rods constructed of neutron-absorbing material. Each rod is movable with respect to the other rods to vary the absorption of neutrons and effect control over neutron flux.

77 FR 21813 - Changes to the Generic Aging Lessons Learned (GALL) Report Revision 2 AMP XI.M41, “Buried and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-11

... NUCLEAR REGULATORY COMMISSION [NRC-2012-0055] Changes to the Generic Aging Lessons Learned (GALL) Report Revision 2 AMP XI.M41, ``Buried and Underground Piping and Tanks'' AGENCY: Nuclear Regulatory... NUREG-1801, Revision 2, ``Generic Aging Lessons Learned (GALL) Report,'' and the NRC staff's aging...

Multiple-wavelength neutron holography with pulsed neutrons

PubMed Central

Hayashi, Kouichi; Ohoyama, Kenji; Happo, Naohisa; Matsushita, Tomohiro; Hosokawa, Shinya; Harada, Masahide; Inamura, Yasuhiro; Nitani, Hiroaki; Shishido, Toetsu; Yubuta, Kunio

2017-01-01

Local structures around impurities in solids provide important information for understanding the mechanisms of material functions, because most of them are controlled by dopants. For this purpose, the x-ray absorption fine structure method, which provides radial distribution functions around specific elements, is most widely used. However, a similar method using neutron techniques has not yet been developed. If one can establish a method of local structural analysis with neutrons, then a new frontier of materials science can be explored owing to the specific nature of neutron scattering—that is, its high sensitivity to light elements and magnetic moments. Multiple-wavelength neutron holography using the time-of-flight technique with pulsed neutrons has great potential to realize this. We demonstrated multiple-wavelength neutron holography using a Eu-doped CaF2 single crystal and obtained a clear three-dimensional atomic image around trivalent Eu substituted for divalent Ca, revealing an interesting feature of the local structure that allows it to maintain charge neutrality. The new holography technique is expected to provide new information on local structures using the neutron technique. PMID:28835917

Multiple-wavelength neutron holography with pulsed neutrons.

PubMed

Hayashi, Kouichi; Ohoyama, Kenji; Happo, Naohisa; Matsushita, Tomohiro; Hosokawa, Shinya; Harada, Masahide; Inamura, Yasuhiro; Nitani, Hiroaki; Shishido, Toetsu; Yubuta, Kunio

2017-08-01

Local structures around impurities in solids provide important information for understanding the mechanisms of material functions, because most of them are controlled by dopants. For this purpose, the x-ray absorption fine structure method, which provides radial distribution functions around specific elements, is most widely used. However, a similar method using neutron techniques has not yet been developed. If one can establish a method of local structural analysis with neutrons, then a new frontier of materials science can be explored owing to the specific nature of neutron scattering-that is, its high sensitivity to light elements and magnetic moments. Multiple-wavelength neutron holography using the time-of-flight technique with pulsed neutrons has great potential to realize this. We demonstrated multiple-wavelength neutron holography using a Eu-doped CaF 2 single crystal and obtained a clear three-dimensional atomic image around trivalent Eu substituted for divalent Ca, revealing an interesting feature of the local structure that allows it to maintain charge neutrality. The new holography technique is expected to provide new information on local structures using the neutron technique.

Cross Calibration of Omnidirectional Orbital Neutron Detectors of Lunar Prospector (LP) and Lunar Exploration Neutron Detector (LEND) by Monte Carlo Simulation

NASA Astrophysics Data System (ADS)

Murray, J.; SU, J. J.; Sagdeev, R.; Chin, G.

2014-12-01

Introduction:Monte Carlo (MC) simulations have been used to investigate neutron production and leakage from the lunar surface to assess the composition of the lunar soil [1-3]. Orbital measurements of lunar neutron flux have been made by the Lunar Prospector Neutron Spectrometer (LPNS)[4] of the Lunar Prospector mission and the Lunar Exploration Neutron Detector (LEND)[5] of the Lunar Reconnaissance Orbiter mission. While both are cylindrical helium-3 detectors, LEND's SETN (Sensor EpiThermal Neutrons) instrument is shorter, with double the helium-3 pressure than that of LPNS. The two instruments therefore have different angular sensitivities and neutron detection efficiencies. Furthermore, the Lunar Prospector's spin-stabilized design makes its detection efficiency latitude-dependent, while the SETN instrument faces permanently downward toward the lunar surface. We use the GEANT4 Monte Carlo simulation code[6] to investigate the leakage lunar neutron energy spectrum, which follows a power law of the form E-0.9 in the epithermal energy range, and the signals detected by LPNS and SETN in the LP and LRO mission epochs, respectively. Using the lunar neutron flux reconstructed for LPNS epoch, we calculate the signal that would have been observed by SETN at that time. The subsequent deviation from the actual signal observed during the LEND epoch is due to the significantly higher intensity of Galactic Cosmic Rays during the anomalous Solar Minimum of 2009-2010. References: [1] W. C. Feldman, et al., (1998) Science Vol. 281 no. 5382 pp. 1496-1500. [2] Gasnault, O., et al.,(2000) J. Geophys. Res., 105(E2), 4263-4271. [3] Little, R. C., et al. (2003), J. Geophys. Res., 108(E5), 5046. [4]W. C. Feldman, et al., (1999) Nucl. Inst. And Method in Phys. Res. A 422, [5] M. L. Litvak, et al., (2012) J.Geophys. Res. 117, E00H32 [6] J. Allison, et al, (2006) IEEE Trans. on Nucl Sci, Vol 53, No 1.

Performance of a MICROMEGAS-based TPC in a high-energy neutron beam

DOE PAGES

Snyder, L.; Manning, B.; Bowden, N. S.; ...

2017-11-01

The MICROMEGAS (MICRO-MEsh GAseous Structure) charge amplification structure has found wide use in many detection applications, especially as a gain stage for the charge readout of Time Projection Chambers (TPCs). We report on the behavior of a MICROMEGAS TPC when operated in a high-energy (up to 800 MeV) neutron beam. It is found that neutron-induced reactions can cause discharges in some drift gas mixtures that are stable in the absence of the neutron beam. The discharges result from recoil ions close to the MICROMEGAS that deposit high specific ionization density and have a limited diffusion time. And for a binarymore » drift gas, increasing the percentage of the molecular component (quench gas) relative to the noble component and operating at lower pressures generally improves stability.« less

Performance of a MICROMEGAS-based TPC in a high-energy neutron beam

NASA Astrophysics Data System (ADS)

Snyder, L.; Manning, B.; Bowden, N. S.; Bundgaard, J.; Casperson, R. J.; Cebra, D. A.; Classen, T.; Duke, D. L.; Gearhart, J.; Greife, U.; Hagmann, C.; Heffner, M.; Hensle, D.; Higgins, D.; Isenhower, D.; King, J.; Klay, J. L.; Geppert-Kleinrath, V.; Loveland, W.; Magee, J. A.; Mendenhall, M. P.; Sangiorgio, S.; Seilhan, B.; Schmitt, K. T.; Tovesson, F.; Towell, R. S.; Walsh, N.; Watson, S.; Yao, L.; Younes, W.

2018-02-01

The MICROMEGAS (MICRO-MEsh GAseous Structure) charge amplification structure has found wide use in many detection applications, especially as a gain stage for the charge readout of Time Projection Chambers (TPCs). Here we report on the behavior of a MICROMEGAS TPC when operated in a high-energy (up to 800 MeV) neutron beam. It is found that neutron-induced reactions can cause discharges in some drift gas mixtures that are stable in the absence of the neutron beam. The discharges result from recoil ions close to the MICROMEGAS that deposit high specific ionization density and have a limited diffusion time. For a binary drift gas, increasing the percentage of the molecular component (quench gas) relative to the noble component and operating at lower pressures generally improves stability.

Are neutron stars crushed? Gravitomagnetic tidal fields as a mechanism for binary-induced collapse

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

Favata, Marc

Numerical simulations of binary neutron stars by Wilson, Mathews, and Marronetti indicated that neutron stars that are stable in isolation can be made to collapse to black holes when placed in a binary. This claim was surprising as it ran counter to the Newtonian expectation that a neutron star in a binary should be more stable, not less. After correcting an error found by Flanagan, Wilson and Mathews found that the compression of the neutron stars was significantly reduced but not eliminated. This has motivated us to ask the following general question: Under what circumstances can general-relativistic tidal interactions causemore » an otherwise stable neutron star to be compressed? We have found that if a nonrotating neutron star possesses a current-quadrupole moment, interactions with a gravitomagnetic tidal field can lead to a compressive force on the star. If this current quadrupole is induced by the gravitomagnetic tidal field, it is related to the tidal field by an equation-of-state-dependent constant called the gravitomagnetic Love number. This is analogous to the Newtonian Love number that relates the strength of a Newtonian tidal field to the induced mass quadrupole moment of a star. The compressive force is almost never larger than the Newtonian tidal interaction that stabilizes the neutron star against collapse. In the case in which a current quadrupole is already present in the star (perhaps as an artifact of a numerical simulation), the compressive force can exceed the stabilizing one, leading to a net increase in the central density of the star. This increase is small (< or approx. 1%) but could, in principle, cause gravitational collapse in a star that is close to its maximum mass. This paper also reviews the history of the Wilson-Mathews-Marronetti controversy and, in an appendix, extends the discussion of tidally induced changes in the central density to rotating stars.« less

Stability tests at Browns Ferry Unit 1 under single-loop operating conditions

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

March-Leuba, J.; Wood, R.T.; Otaduy, P.J.

1986-07-01

The results of neutronic stability tests performed on February 9, 1985, at the Browns Ferry Nuclear Power Plant Unit 1 under single-loop operation (SLO) conditions are documented. The main conclusions of the tests are presented.

Ab initio calculation of the neutron-proton mass difference

NASA Astrophysics Data System (ADS)

Borsanyi, Sz.; Durr, S.; Fodor, Z.; Hoelbling, C.; Katz, S. D.; Krieg, S.; Lellouch, L.; Lippert, T.; Portelli, A.; Szabo, K. K.; Toth, B. C.

2015-03-01

The existence and stability of atoms rely on the fact that neutrons are more massive than protons. The measured mass difference is only 0.14% of the average of the two masses. A slightly smaller or larger value would have led to a dramatically different universe. Here, we show that this difference results from the competition between electromagnetic and mass isospin breaking effects. We performed lattice quantum-chromodynamics and quantum-electrodynamics computations with four nondegenerate Wilson fermion flavors and computed the neutron-proton mass-splitting with an accuracy of 300 kilo-electron volts, which is greater than 0 by 5 standard deviations. We also determine the splittings in the Σ, Ξ, D, and Ξcc isospin multiplets, exceeding in some cases the precision of experimental measurements.

Efficacy of the treatments used for the control of Caligus rogercresseyi infecting Atlantic salmon, Salmo salar L., in a new fish-farming location in Region XI, Chile.

PubMed

Bravo, S; Nuñez, M; Silva, M T

2013-03-01

Caligus rogercresseyi is the most important parasite affecting Atlantic salmon and rainbow trout farming in sea water in Chile. After the outbreaks of the infectious salmon anaemia recorded in Region X from 2007, the salmon industry has expanded southwards to Region XI, where 60% of Atlantic salmon in Chile is now produced. In parallel with the relocation of salmon production, sea lice infestation has also spread to Region XI, and today C. rogercresseyi is the most serious threat to the salmon-farming industry in this region. The results obtained through a year of monitoring between September 2007 and August 2008 on a farm located in the 'Las Guaitecas Archipelago' in Region XI (44°S; 74°W) showed that treatments with emamectin benzoate and deltamethrin did not give the expected control of Caligus. Failures of the treatments were associated with the loss of sensitivity recorded for C. rogercresseyi to emamectin benzoate in Region X. In addition, a major influence was the lack of delousing coordination measures with the neighbouring farms sharing the same area in that period. © 2013 Blackwell Publishing Ltd.

Neutron-beam-shaping assembly for boron neutron-capture therapy

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

Zaidi, L.; Kashaeva, E. A.; Lezhnin, S. I.

A neutron-beam-shaping assembly consisting of a moderator, a reflector, and an absorber is used to form a therapeutic neutron beam for the boron neutron-capture therapy of malignant tumors at accelerator neutron sources. A new structure of the moderator and reflector is proposed in the present article, and the results of a numerical simulation of the neutron spectrum and of the absorbed dose in a modified Snyder head phantom are presented. The application of a composite moderator and of a composite reflector and the implementation of neutron production at the proton energy of 2.3MeV are shown to permit obtaining a high-qualitymore » therapeutic neutron beam.« less

The in vivo Therapeutic Effect of Free Wanderer Powder (逍 遙 散 xiāo yáo sǎn, Xiaoyaosan) on Mice with 4T1 Cell Induced Breast Cancer Model

PubMed Central

Chen, Wen-Fang; Xu, Li; Yu, Chung-Him; Ho, Chui-Kwan; Wu, Ka; Leung, Gina CW; Wong, Man-Sau

2012-01-01

In the present study, we investigated the therapeutic effect of a classical TCM formula, Free Wanderer Powder (逍遙散 xiāo yáo sǎn), in a breast cancer mouse model induced with estrogen-insensitive breast cancer 4T1 cells. Ovariectomized Balb/c mice (6-8 weeks) or sham mice were injected into the fourth mammary fat pad with 4T1 cells in which tumors were palpable 7 days after injection. On the eighth day, the mice were divided into 4 groups and tubefed daily with vehicle, Free Wanderer Powder (逍遙散 xiāo yáo sǎn) formula or tamoxifen for 28 days. Tumor growth inhibition and the decrease of the average tumor mass were most evident in mice treated with Free Wanderer Powder (逍遙散 xiāo yáo sǎn). Free Wanderer Powder (逍遙散 xiāo yáo sǎn) treatment significantly reduced Bcl-2 and elevated Bax and p53 protein expressions in breast cancer tumor. These results were further confirmed by immunohistochemisty. Tamoxifen could decrease spleen mass and Bcl-2 protein expression, increase the Bax protein expression as well as exert uterotrophic effects by increasing uterus index and inducing the gene expressions in the uterus. Taken together, these results show that Free Wanderer Powder (逍遙散 xiāo yáo sǎn) treatment induced apoptosis at protein level and inhibited the tumor growth in 4T1-induced ovariectomized Balb/c female mice, indicating the possibility of its future use for treatment of estrogen-insensitive breast caner. PMID:24716117

Caesarean section rate and cost control effectiveness of case payment reform in the new cooperative medical scheme for delivery: evidence from Xi County, China.

PubMed

Liu, Shuang; Wang, Jing; Zhang, Liang; Zhang, Xiang

2018-03-09

In China, increases in both the caesarean section (CS) rates and delivery costs have raised questions regarding the reform of the medical insurance payment system. Case payment is useful for regulating the behaviour of health providers and for controlling the CS rates and excessive increases in medical expenses. New Cooperative Medical Scheme (NCMS) agencies in Xi County in Henan Province piloted a case payment reform (CPR) in delivery for inpatients. We aimed to observe the changes in the CS rates, compare the changes in delivery-related variables, and identify variables related to delivery costs before and after the CPR in Xi County. Overall, 28,314 cases were selected from the Xi County NCMS agency from 2009 to 2010 and from 2014 to 2015. One-way ANOVA and chi-square tests were used to compare the distributions of CS and vaginal delivery (VD) before and after the CPR under different indicators. We applied multivariate linear regressions for the total medical cost of the VD and CS groups and total samples to identify the relationships between medical expenses and variables. The CS rates in Xi County increased from 26.1% to 32.5% after the CPR. The length of stay (LOS), total medical cost, and proportion of county hospitals increased in the CS and VD groups after the CPR, which had significant differences. The total medical cost in the CS and VD groups as well as the total samples was significantly influenced by inpatient age, LOS, and hospital type, and had a significant correlation with the CPR in the VD group and the total samples. The CPR might fail to control the growth of unreasonable medical expenses and regulate the behaviour of providers, which possibly resulted from the unreasonable compensation standard of case payments, prolonged LOS, and the increasing proportion of county hospitals. The NCMS should modify the case payment standard of delivery to inhibit providers' motivation to render CS services. The LOS should be controlled by implementing clinical

Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator

NASA Astrophysics Data System (ADS)

Čufar, Aljaž; Batistoni, Paola; Conroy, Sean; Ghani, Zamir; Lengar, Igor; Milocco, Alberto; Packer, Lee; Pillon, Mario; Popovichev, Sergey; Snoj, Luka; JET Contributors

2017-03-01

At the Joint European Torus (JET) the ex-vessel fission chambers and in-vessel activation detectors are used as the neutron production rate and neutron yield monitors respectively. In order to ensure that these detectors produce accurate measurements they need to be experimentally calibrated. A new calibration of neutron detectors to 14 MeV neutrons, resulting from deuterium-tritium (DT) plasmas, is planned at JET using a compact accelerator based neutron generator (NG) in which a D/T beam impinges on a solid target containing T/D, producing neutrons by DT fusion reactions. This paper presents the analysis that was performed to model the neutron source characteristics in terms of energy spectrum, angle-energy distribution and the effect of the neutron generator geometry. Different codes capable of simulating the accelerator based DT neutron sources are compared and sensitivities to uncertainties in the generator's internal structure analysed. The analysis was performed to support preparation to the experimental measurements performed to characterize the NG as a calibration source. Further extensive neutronics analyses, performed with this model of the NG, will be needed to support the neutron calibration experiments and take into account various differences between the calibration experiment and experiments using the plasma as a source of neutrons.

Ancient Guest Stars as harbingers of neutron star formation

NASA Astrophysics Data System (ADS)

Wang, Zhen-Ru

The well-known AD 1006, 1054, 1572, and 1604 were described as "Guest Stars" by Chinese, Japanese and Korean. In most cases, it might thus be possible to expect a Guest Star to be a term for supernova or nova. There are a lot of records concerning ancient Guest Stars in Chinese historical books. Two catalogues were compiled by Xi (1955) and Xi and Bo (1965, 1966) that listed 90 probable novae or supernovae observed between 1400 BC and AD 1700. Clark and Stephenson (1977), Ho (1962) and Kanda (1935) collected more or less similar records. Among all the historical records more than 80% are from China. The discussion presented in this paper is based on them.

A debris disk around an isolated young neutron star.

PubMed

Wang, Zhongxiang; Chakrabarty, Deepto; Kaplan, David L

2006-04-06

Pulsars are rotating, magnetized neutron stars that are born in supernova explosions following the collapse of the cores of massive stars. If some of the explosion ejecta fails to escape, it may fall back onto the neutron star or it may possess sufficient angular momentum to form a disk. Such 'fallback' is both a general prediction of current supernova models and, if the material pushes the neutron star over its stability limit, a possible mode of black hole formation. Fallback disks could dramatically affect the early evolution of pulsars, yet there are few observational constraints on whether significant fallback occurs or even the actual existence of such disks. Here we report the discovery of mid-infrared emission from a cool disk around an isolated young X-ray pulsar. The disk does not power the pulsar's X-ray emission but is passively illuminated by these X-rays. The estimated mass of the disk is of the order of 10 Earth masses, and its lifetime (> or = 10(6) years) significantly exceeds the spin-down age of the pulsar, supporting a supernova fallback origin. The disk resembles protoplanetary disks seen around ordinary young stars, suggesting the possibility of planet formation around young neutron stars.

Online SEOP polarization of Large Area Neutron Spin Filters

NASA Astrophysics Data System (ADS)

Babcock, Earl; Salhi, Zahir; Ioffe, Alexander

2015-04-01

The Juelich Center for neutron Science has a program to use SEOP polarized 3He Neutron Spin Filters (3He NSF) on many neutron scattering instruments. The main applications are for polarization analysis of the scattered beam. As such, the devices must operate in close proximity to the neutron sample and sample environment which can include complicated cryostats, humidity and pressure cells, and high field magnets. Thus we have developed novel magnetic cavities to house the 3He NSF cells which allow for simultaneous optical pumping on the instruments. Further we continually develop and redevelop the laser sources which must be relatively narrow band and have long term (i.e. months) stability and robust operation. The first fully operational polarizer has been used continuously for over 2, 60-day reactor cycles at the FRM2. This device uses a 12.5 cm I.D. 3He cell, and has a 3He storage lifetime, including the cells lifetime, in excess of 200 hours with the cell about 60 cm from the sample position inside a 1.2 T electromagnet, and has achieved over 75% 3He polarisation when fully optimized. This talk will describe the magnetic cavities, and laser sources as well as provide a description of the completed 3He polarizer devices.

Neutron Transport Simulations for NIST Neutron Lifetime Experiment

NASA Astrophysics Data System (ADS)

Li, Fangchen; BL2 Collaboration Collaboration

2016-09-01

Neutrons in stable nuclei can exist forever; a free neutron lasts for about 15 minutes on average before it beta decays to a proton, an electron, and an antineutrino. Precision measurements of the neutron lifetime test the validity of weak interaction theory and provide input into the theory of the evolution of light elements in the early universe. There are two predominant ways of measuring the neutron lifetime: the bottle method and the beam method. The bottle method measures decays of ultracold neutrons that are stored in a bottle. The beam method measures decay protons in a beam of cold neutrons of known flux. An improved beam experiment is being prepared at the National Institute of Science and Technology (Gaithersburg, MD) with the goal of reducing statistical and systematic uncertainties to the level of 1 s. The purpose of my studies was to develop computer simulations of neutron transport to determine the beam collimation and study the neutron distribution's effect on systematic effects for the experiment, such as the solid angle of the neutron flux monitor. The motivation for the experiment and the results of this work will be presented. This work was supported, in part, by a Grant to Gettysburg College from the Howard Hughes Medical Institute through the Precollege and Undergraduate Science Education Program.

Neutron range spectrometer

DOEpatents

Manglos, Stephen H.

1989-06-06

A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are collimnated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. The computer solves the following equation in the analysis: ##EQU1## where: N(x).DELTA.x=the number of neutron interactions measured between a position x and x+.DELTA.x, A.sub.i (E.sub.i).DELTA.E.sub.i =the number of incident neutrons with energy between E.sub.i and E.sub.i +.DELTA.E.sub.i, and C=C(E.sub.i)=N .sigma.(E.sub.i) where N=the number density of absorbing atoms in the position sensitive counter means and .sigma. (E.sub.i)=the average cross section of the absorbing interaction between E.sub.i and E.sub.i +.DELTA.E.sub.i.

Staged Z-pinch Experiments at the 1MA Zebra pulsed-power generator: Neutron measurements

NASA Astrophysics Data System (ADS)

Ruskov, Emil; Darling, T.; Glebov, V.; Wessel, F. J.; Anderson, A.; Beg, F.; Conti, F.; Covington, A.; Dutra, E.; Narkis, J.; Rahman, H.; Ross, M.; Valenzuela, J.

2017-10-01

We report on neutron measurements from the latest Staged Z-pinch experiments at the 1MA Zebra pulsed-power generator. In these experiments a hollow shell of argon or krypton gas liner, injected between the 1 cm anode-cathode gap, compresses a deuterium plasma target of varying density. Axial magnetic field Bz <= 2 kGs, applied throughout the pinch region, stabilizes the Rayleigh-Taylor instability. The standard silver activation diagnostics and 4 plastic scintillator neutron Time of Flight (nTOF) detectors are augmented with a large area ( 1400 cm2) liquid scintillator detector to which fast gatedPhotek photomultipliers are attached. Sample data from these neutron diagnostics systems is presented. Consistently high neutron yields YDD >109 are measured, with highest yield of 2.6 ×109 . A pair of horizontally and vertically placed plastic scintillator nTOFs suggest isotropic i.e. thermonuclear origin of the neutrons produced. nTOF data from the liquid scintillator detector was cross-calibrated with the silver activation detector, and can be used for accurate calculation of the neutron yield. Funded by the Advanced Research Projects Agency - Energy, under Grant Number DE-AR0000569.

Unexpectedly large charge radii of neutron-rich calcium isotopes

DOE PAGES

Garcia Ruiz, R. F.; Bissell, M. L.; Blaum, K.; ...

2016-02-08

Here, despite being a complex many-body system, the atomic nucleus exhibits simple structures for certain ‘magic’ numbers of protons and neutrons. The calcium chain in particular is both unique and puzzling: evidence of doubly magic features are known in 40,48Ca, and recently suggested in two radioactive isotopes, 52,54Ca. Although many properties of experimentally known calcium isotopes have been successfully described by nuclear theory, it is still a challenge to predict the evolution of their charge radii. Here we present the first measurements of the charge radii of 49,51,52Ca, obtained from laser spectroscopy experiments at ISOLDE, CERN. The experimental results aremore » complemented by state-of-the-art theoretical calculations. The large and unexpected increase of the size of the neutron-rich calcium isotopes beyond N = 28 challenges the doubly magic nature of 52Ca and opens new intriguing questions on the evolution of nuclear sizes away from stability, which are of importance for our understanding of neutron-rich atomic nuclei.« less

STEAM FORMING NEUTRONIC REACTOR AND METHOD OF OPERATING IT

DOEpatents

Untermyer, S.

1960-05-10

The heterogeneous reactor is liquid moderated and cooled by a steam forming coolant and is designed to produce steam from the coolant directly within the active portion of the reactor while avoiding the formation of bubbles in the liquid moderator. This reactor achieves inherent stability as a result of increased neutron leakage and increased neutron resonance absorption in the U/sup 238/ fuel with the formation of bubbles. The invention produces certain conditions under which the formation of vapor bubbles as a result of a neutron flux excursion from the injection of a reactivity increment into the reactor will operate to nullify the reactivity increment within a sufficiently short period of time to prevent unsafe reactor operating conditions from developing. This is obtained by disposing a plurality of fuel elements within a mass of steam forming coolant in the core with the ratio of the volume of steam forming coolant to the volume of fissionable isotopes being within the range yielding a multiplication factor greater than unity and a negative reactivity to core void coefficient at the boiling temperature of the coolant.

Neutron spectrometry in a mixed field of neutrons and protons with a phoswich neutron detector Part I: response functions for photons and neutrons of the phoswich neutron detector

NASA Astrophysics Data System (ADS)

Takada, M.; Taniguchi, S.; Nakamura, T.; Nakao, N.; Uwamino, Y.; Shibata, T.; Fujitaka, K.

2001-06-01

We have developed a phoswich neutron detector consisting of an NE213 liquid scintillator surrounded by an NE115 plastic scintillator to distinguish photon and neutron events in a charged-particle mixed field. To obtain the energy spectra by unfolding, the response functions to neutrons and photons were obtained by the experiment and calculation. The response functions to photons were measured with radionuclide sources, and were calculated with the EGS4-PRESTA code. The response functions to neutrons were measured with a white neutron source produced by the bombardment of 135 MeV protons onto a Be+C target using a TOF method, and were calculated with the SCINFUL code, which we revised in order to calculate neutron response functions up to 135 MeV. Based on these experimental and calculated results, response matrices for photons up to 20 MeV and neutrons up to 132 MeV could finally be obtained.

Measurement of Continuous-Energy Neutron-Incident Neutron-Production Cross Section

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

Shigyo, Nobuhiro; Kunieda, Satoshi; Watanabe, Takehito

Continuous energy neutron-incident neutron-production double differential cross sections were measured at the Weapons Neutron Research (WNR) facility of the Los Alamos Neutron Science Center. The energy of emitted neutrons was derived from the energy deposition in a detector. The incident-neutron energy was obtained by the time-of-flight method between the spallation target of WNR and the emitted neutron detector. Two types of detectors were adopted to measure the wide energy range of neutrons. The liquid organic scintillators covered up to 100 MeV. The recoil proton detectors that constitute the recoil proton radiator and phoswich type NaI (Tl) scintillators were used formore » neutrons above several tens of MeV. Iron and lead were used as sample materials. The experimental data were compared with the evaluated nuclear data, the results of GNASH, JQMD, and PHITS codes.« less

Observation of Neutron Skyshine from an Accelerator Based Neutron Source

NASA Astrophysics Data System (ADS)

Franklyn, C. B.

2011-12-01

A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >1011 nṡs-1. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

Observation of Neutron Skyshine from an Accelerator Based Neutron Source

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

Franklyn, C. B.

2011-12-13

A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >10{sup 11} n{center_dot}s{sup -1}. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It ismore » further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.« less

Neutron-$$\\gamma$$ competition for β-delayed neutron emission

DOE PAGES

Mumpower, Matthew Ryan; Kawano, Toshihiko; Moller, Peter

2016-12-19

Here we present a coupled quasiparticle random phase approximation and Hauser-Feshbach (QRPA+HF) model for calculating delayed particle emission. This approach uses microscopic nuclear structure information, which starts with Gamow-Teller strength distributions in the daughter nucleus and then follows the statistical decay until the initial available excitation energy is exhausted. Explicitly included at each particle emission stage is γ-ray competition. We explore this model in the context of neutron emission of neutron-rich nuclei and find that neutron-γ competition can lead to both increases and decreases in neutron emission probabilities, depending on the system considered. Finally, a second consequence of this formalismmore » is a prediction of more neutrons on average being emitted after β decay for nuclei near the neutron drip line compared to models that do not consider the statistical decay.« less

Subjective well-being of the elderly in Xi Cheng District, Beijing

PubMed Central

Li, Shuo; Xie, Zhaohui; Shao, Jun; Xiao, Cunli; Tian, Liang; Zhao, Rongfeng; Gong, Jiakai; Han, Jinxiang; Wang, Yue; Han, Chao; Dang, Liping; Zhang, Yushi; Chen, Bo; Luo, Xiaojing; Guo, Wei

2012-01-01

Background In 2010 the Beijing Municipal Government promulgated a policy aimed at improving the quality of life and subjective well-being of elderly residents that included a component focused on mental health. Aim Identify factors associated with subjective well-being in a representative sample of elderly residents of Xi Cheng District in Beijing. Methods This cross-sectional study administered a self-completion survey to a stratified random sample of 2342 residents of Xi Cheng District who were 60 to 80 years of age. The level of well-being was assessed using a validated Chinese version of the Memorial University of Newfoundland Scale of Happiness (MUNSH). Detailed socioeconomic variables were obtained using a questionnaire developed by the authors. Social support, anxiety, and depression were assessed using validated Chinese versions of the Social Support Rating Scale (SSRS), Self-rating Anxiety Scale (SAS), and Self-rating Depression Scale (SDS). Results Among the 2342 respondents, 1616 (69.0%) had a total MUNSH score of 32 or above, indicating a high level of happiness; 423 (18.1%) has a total SSRS score 32 or below, indicating poor social support; 201 (8.6%) had a total SDS score of 53 or above, indicating significant depression; and 126 (5.3%) had a total SAS score of 50 or above, indicating significant anxiety. In the multivariate regression analysis the self-reported level of depression was the most important factor related to well-being. Anxiety, social support, income level, the quality of family relationships, the ability to self-regulate emotions, and regular exercise were also significantly related to well-being; but gender, marital status, age and educational level were not associated with well-being. Conclusion Among elderly urban residents in Beijing, self-reports of poor subjective well-being are closely associated with self-reports of depressive and anxiety symptoms and also associated with social factors such as social support, income level and

The Settings, Pros and Cons of the New Surgical Robot da Vinci Xi System for Transoral Robotic Surgery (TORS): A Comparison With the Popular da Vinci Si System.

PubMed

Kim, Da Hee; Kim, Hwan; Kwak, Sanghyun; Baek, Kwangha; Na, Gina; Kim, Ji Hoon; Kim, Se Heon

2016-10-01

The da Vinci system (da Vinci Surgical System; Intuitive Surgical Inc.) has rapidly developed in several years from the S system to the Si system and now the Xi System. To investigate the surgical feasibility and to provide workflow guidance for the newly released system, we used the new da Vinci Xi system for transoral robotic surgery (TORS) on a cadaveric specimen. Bilateral supraglottic partial laryngectomy, hypopharyngectomy, lateral oropharyngectomy, and base of the tongue resection were serially performed in search of the optimal procedures with the new system. The new surgical robotic system has been upgraded in all respects. The telescope and camera were incorporated into one system, with a digital end-mounted camera. Overhead boom rotation allows multiquadrant access without axis limitation, the arms are now thinner and longer with grabbing movements for easy adjustments. The patient clearance button dramatically reduces external collisions. The new surgical robotic system has been optimized for improved anatomic access, with better-equipped appurtenances. This cadaveric study of TORS offers guidance on the best protocol for surgical workflow with the new Xi system leading to improvements in the functional results of TORS.

Characteristics of bacterial and fungal aerosols during the autumn haze days in Xi'an, China

NASA Astrophysics Data System (ADS)

Li, Yanpeng; Fu, Honglei; Wang, Wei; Liu, Jun; Meng, Qinglong; Wang, Wenke

2015-12-01

In recent years, haze pollution has become one of the most critical environmental issues in Xi'an, China, with particular matter (PM) being one of the top pollutants. As an important fraction of PM, bioaerosols may have adverse effects on air quality and human health. In this study, to better understand the characteristics of such biological aerosols, airborne microbial samples were collected by using an Andersen six-stage sampler in Xi'an from October 8th to 22nd, 2014. The concentration, size distribution and genera of airborne viable bacteria and fungi were comparably investigated during the haze days and non-haze days. Correlations of bioaerosol levels with meteorological parameters and PM concentrations were also examined. The results showed that the daily average concentrations of airborne viable bacteria and fungi during the haze days, 1102.4-1736.5 and 1466.2-1703.9 CFU/m3, respectively, were not only much higher than those during the non-haze days, but also exceeded the recommended permissible limit values. Comparing to size distributions during the non-haze days, slightly different patterns for bacterial aerosols and similar single-peak distribution pattern for fungal aerosols were observed during the haze days. Moreover, more allergic and infectious genera (e.g. Neisseria, Aspergillus, and Paecilomyces) in bioaerosols were identified during the haze days than during non-haze days. The present results reveal that bioaerosols may have more significant effects on public health and urban air quality during the haze days than during non-haze days.

Methods for absorbing neutrons

DOEpatents

Guillen, Donna P [Idaho Falls, ID; Longhurst, Glen R [Idaho Falls, ID; Porter, Douglas L [Idaho Falls, ID; Parry, James R [Idaho Falls, ID

2012-07-24

A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

On the stability and maximum mass of differentially rotating relativistic stars

NASA Astrophysics Data System (ADS)

Weih, Lukas R.; Most, Elias R.; Rezzolla, Luciano

2018-01-01

The stability properties of rotating relativistic stars against prompt gravitational collapse to a black hole are rather well understood for uniformly rotating models. This is not the case for differentially rotating neutron stars, which are expected to be produced in catastrophic events such as the merger of binary system of neutron stars or the collapse of a massive stellar core. We consider sequences of differentially rotating equilibrium models using the j-constant law and by combining them with their dynamical evolution, we show that a sufficient stability criterion for differentially rotating neutron stars exists similar to the one of their uniformly rotating counterparts. Namely: along a sequence of constant angular momentum, a dynamical instability sets in for central rest-mass densities slightly below the one of the equilibrium solution at the turning point. In addition, following Breu & Rezzolla, we show that `quasi-universal' relations can be found when calculating the turning-point mass. In turn, this allows us to compute the maximum mass allowed by differential rotation, Mmax,dr, in terms of the maximum mass of the non-rotating configuration, M_{_TOV}, finding that M_{max, dr} ˜eq (1.54 ± 0.05) M_{_TOV} for all the equations of state we have considered.

Characterization of Deuteron-Deuteron Neutron Generators

NASA Astrophysics Data System (ADS)

Waltz, Cory Scott

A facility based on a next-generation, high-flux D-D neutron generator (HFNG) was commissioned at the University of California Berkeley. The characterization of the HFNG is presented in the following study. The current generator design produces near mono-energetic 2.45 MeV neutrons at outputs of 108 n/s. Calculations provided show that future conditioning at higher currents and voltages will allow for a production rate over 1010 n/s. Characteristics that effect the operational stability include the suppression of the target-emitted back streaming electrons, target sputtering and cooling, and ion beam optics. Suppression of secondary electrons resulting from the deuterium beam striking the target was achieved via the implementation of an electrostatic shroud with a voltage offset of greater than -400 V relative to the target. Ion beam optics analysis resulted in the creation of a defocussing extraction nozzle, allowing for cooler target temperatures and a more compact design. To calculate the target temperatures, a finite difference method (FDM) solver incorporating the additional heat removal effects of subcooled boiling was developed. Validation of the energy balance results from the finite difference method calculations showed the iterative solver converged to heat removal results within about 3% of the expected value. Testing of the extraction nozzle at 1.43 mA and 100 kV determined that overheating of the target did not occur as the measured neutron flux of the generator was near predicted values. Many factors, including the target stopping power, deuterium atomic species, and target loading ratio, affect the flux distribution of the HFNG neutron generator. A detailed analysis to understand these factors effects is presented. Comparison of the calculated flux of the neutron generator using deuteron depth implantation data, neutron flux distribution data, and deuterium atomic species data matched the experimentally calculated flux determined from indium foil

Net accumulation rates derived from ice core stable isotope records of Pío XI glacier, Southern Patagonia Icefield

NASA Astrophysics Data System (ADS)

Schwikowski, M.; Schläppi, M.; Santibañez, P.; Rivera, A.; Casassa, G.

2012-12-01

Pío XI, the largest glacier of the Southern Patagonia Icefield, reached its neoglacial maximum extent in 1994 and is one of the few glaciers in that area which is not retreating. In view of the recent warming it is important to understand glacier responses to climate changes. Due to its remoteness and the harsh conditions in Patagonia, no systematic mass balance studies have been performed. In this study we derived net accumulation rates for the period 2000 to 2006 from a 50 m (33.2 4 m weq) ice core collected in the accumulation area of Pío XI (2600 m a.s.l., 49°16´40´´ S, 73°21´14´´ W). Borehole temperatures indicate near temperate ice, but the average melt percent is only 16% ± 14%. Records of stable isotopes are well preserved and were used for identification of annual layers. Net accumulation rates range from 3.4 to 7.1 water equivalent (m weq) with an average of 5.8 m weq, comparable to precipitation amounts at the Chilean coast, but not as high as expected for the Icefield. Ice core stable isotope data correlate well with upper air temperatures and may be used as temperature proxy.

SELF-REACTIVATING NEUTRON SOURCE FOR A NEUTRONIC REACTOR

DOEpatents

Newson, H.W.

1959-02-01

Reactors of the type employing beryllium in a reflector region around the active portion and to a neutron source for use therewith are discussed. The neutron source is comprised or a quantity of antimony permanently incorporated in, and as an integral part of, the reactor in or near the beryllium reflector region. During operation of the reactor the natural occurring antimony isotope of atomic weight 123 absorbs neutrons and is thereby transformed to the antimony isotope of atomic weight 124, which is radioactive and emits gamma rays. The gamma rays react with the beryllium to produce neutrons. The beryllium and antimony thus cooperate to produce a built in neutron source which is automatically reactivated by the operation of the reactor itself and which is of sufficient strength to maintain the slow neutron flux at a sufficiently high level to be reliably measured during periods when the reactor is shut down.

Response function of single crystal synthetic diamond detectors to 1-4 MeV neutrons for spectroscopy of D plasmas

NASA Astrophysics Data System (ADS)

Rebai, M.; Giacomelli, L.; Milocco, A.; Nocente, M.; Rigamonti, D.; Tardocchi, M.; Camera, F.; Cazzaniga, C.; Chen, Z. J.; Du, T. F.; Fan, T. S.; Giaz, A.; Hu, Z. M.; Marchi, T.; Peng, X. Y.; Gorini, G.

2016-11-01

A Single-crystal Diamond (SD) detector prototype was installed at Joint European Torus (JET) in 2013 and the achieved results have shown its spectroscopic capability of measuring 2.5 MeV neutrons from deuterium plasmas. This paper presents measurements of the SD response function to monoenergetic neutrons, which is a key point for the development of a neutron spectrometer based on SDs and compares them with Monte Carlo simulations. The analysis procedure allows for a good reconstruction of the experimental results. The good pulse height energy resolution (equivalent FWHM of 80 keV at 2.5 MeV), gain stability, insensitivity to magnetic field, and compact size make SDs attractive as compact neutron spectrometers of high flux deuterium plasmas, such as for instance those needed for the ITER neutron camera.

Response function of single crystal synthetic diamond detectors to 1-4 MeV neutrons for spectroscopy of D plasmas

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

Rebai, M., E-mail: marica.rebai@mib.infn.it; Nocente, M.; Rigamonti, D.

2016-11-15

A Single-crystal Diamond (SD) detector prototype was installed at Joint European Torus (JET) in 2013 and the achieved results have shown its spectroscopic capability of measuring 2.5 MeV neutrons from deuterium plasmas. This paper presents measurements of the SD response function to monoenergetic neutrons, which is a key point for the development of a neutron spectrometer based on SDs and compares them with Monte Carlo simulations. The analysis procedure allows for a good reconstruction of the experimental results. The good pulse height energy resolution (equivalent FWHM of 80 keV at 2.5 MeV), gain stability, insensitivity to magnetic field, and compactmore » size make SDs attractive as compact neutron spectrometers of high flux deuterium plasmas, such as for instance those needed for the ITER neutron camera.« less

Thermo-luminescence and neutron absorption cross section evaluations of compounds of Lithium based oxide ceramic breeders in Li-Zr-O system

NASA Astrophysics Data System (ADS)

Mukherjee, Sumanta; Naik, Yeshwant

2018-04-01

Lithium-zirconium based oxides were prepared by combustion route. Thermal analysis (TG and DTA) was used to study the combustion process. The nucleation and growth stages were identified and their activation energies were predicted. The suitability of these oxide breeders was evaluated based on their radiation stability, variation in thermal behavior upon γ irradiation, neutron absorption and tritium breeding characteristics. Nuclear properties of these oxide ceramics were evaluated with a view to use them as efficient neutron absorbers and simultaneously breed tritium. Total neutron absorption cross sections were evaluated as a function of neutron energy in the range of 0 to 20 MeV. Resonant absorption is predicted for the neutron of energy 2.3 keV manly due to contribution from neutron induced nuclear reactions of 7Li in this energy range.

Stability Estimation of ABWR on the Basis of Noise Analysis

NASA Astrophysics Data System (ADS)

Furuya, Masahiro; Fukahori, Takanori; Mizokami, Shinya; Yokoya, Jun

In order to investigate the stability of a nuclear reactor core with an oxide mixture of uranium and plutonium (MOX) fuel installed, channel stability and regional stability tests were conducted with the SIRIUS-F facility. The SIRIUS-F facility was designed and constructed to provide a highly accurate simulation of thermal-hydraulic (channel) instabilities and coupled thermalhydraulics-neutronics instabilities of the Advanced Boiling Water Reactors (ABWRs). A real-time simulation was performed by modal point kinetics of reactor neutronics and fuel-rod thermal conduction on the basis of a measured void fraction in a reactor core section of the facility. A time series analysis was performed to calculate decay ratio and resonance frequency from a dominant pole of a transfer function by applying auto regressive (AR) methods to the time-series of the core inlet flow rate. Experiments were conducted with the SIRIUS-F facility, which simulates ABWR with MOX fuel installed. The variations in the decay ratio and resonance frequency among the five common AR methods are within 0.03 and 0.01 Hz, respectively. In this system, the appropriate decay ratio and resonance frequency can be estimated on the basis of the Yule-Walker method with the model order of 30.

A GDT-based fusion neutron source for academic and industrial applications

NASA Astrophysics Data System (ADS)

Anderson, J. K.; Forest, C. B.; Mirnov, V. V.; Peterson, E. E.; Waleffe, R.; Wallace, J.; Harvey, R. W.

2017-10-01

The design of a fusion neutron source based on the gas dynamic trap (GDT) configuration is underway. The motivation is both the ends and the means. There are immediate applications for neutrons including medical isotope production and actinide burners. Taking the next step in the magnetic mirror path will leverage advances in high-temperature superconducting magnets and additive manufacturing in confining a fusion plasma, and both the technological and physics bases exist. Recent breakthrough results at the GDT facility in Russia demonstrate stable confinement of a beta 60% mirror plasma at high Te ( 1 keV). These scale readily to a fusion neutron source with an increase in magnetic field, mirror ratio, and ion energy. Studies of a next-step compact device focus on calculations of MHD equilibrium and stability, and Fokker-Planck modeling to optimize the heating scenario. The conceptualized device uses off-the-shelf MRI magnets for a 1 T central field, REBCO superconducting mirror coils (which can currently produce fields in excess of 30T), and existing 75 keV NBI and 140 GHz ECRH. High harmonic fast wave injection is damped on beam ions, dramatically increasing the fusion reactivity for an incremental bump in input power. MHD stability is achieved with the vortex confinement scheme, where a biasing profile imposes optimal ExB rotation of the plasma. Liquid metal divertors are being considered in the end cells. Work supported by the Wisconsin Alumni Research Foundation.

Neutron imaging integrated circuit and method for detecting neutrons

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

Nagarkar, Vivek V.; More, Mitali J.

The present disclosure provides a neutron imaging detector and a method for detecting neutrons. In one example, a method includes providing a neutron imaging detector including plurality of memory cells and a conversion layer on the memory cells, setting one or more of the memory cells to a first charge state, positioning the neutron imaging detector in a neutron environment for a predetermined time period, and reading a state change at one of the memory cells, and measuring a charge state change at one of the plurality of memory cells from the first charge state to a second charge statemore » less than the first charge state, where the charge state change indicates detection of neutrons at said one of the memory cells.« less

Thermal Neutron Radiography using a High-flux Compact Neutron Generator

NASA Astrophysics Data System (ADS)

Taylor, Michael; Sengbusch, Evan; Seyfert, Chris; Moll, Eli; Radel, Ross

A novel neutron imaging system has been designed and constructed by Phoenix Nuclear Labs to investigate specimens when conventional X-ray imaging will not suffice. A first-generation electronic neutron generator is actively being used by the United States Army and is coupled with activation films for neutron radiography to inspect munitions and other critical defence and aerospace components. A second-generation system has been designed to increase the total neutron output from an upgraded gaseous deuterium target to 5×1011 DD n/s, generating higher neutron flux at the imaging plane and dramatically reducing interrogation time, while maintaining high spatial resolution and low geometric unsharpness. A description of the neutron generator and imaging system, including the beamline, target and detector platform, is given in this paper. State of the art neutron moderators, collimators and imaging detector components are also discussed in the context of increasing specimen throughput and optimizing image quality. Neutron radiographs captured with the neutron radiography system will be further compared against simulated images using the MCNP nuclear simulation code.

Calculations of the β-decay half-lives of neutron-deficient nuclei

NASA Astrophysics Data System (ADS)

Tan, Wenjin; Ni, Dongdong; Ren, Zhongzhou

2017-05-01

In this work, β+/EC decays of some medium-mass nuclei are investigated within the extended quasiparticle random-phase approximation (QRPA), where neutron-neutron, proton-proton and neutron-proton (np) pairing correlations are taken into consideration in the specialized Hartree-Fock-Bogoliubov (HFB) transformation. In addition to the pairing interaction, the Brückner G-matrix obtained with the charge-dependent Bonn nucleon-nucleon force is used for the residual particle-particle and particle-hole interactions. Calculations are performed for even-even proton-rich isotopes ranging from Z=24 to Z=34. It is found that the np pairing interaction plays a significant role in β-decay for some nuclei far from stability. Compared with other theoretical calculations, our calculations show good agreement with the available experimental data. Predictions of β-decay half-lives for some very neutron-deficient nuclei are made for reference. Supported by National Nature Science Foundation of China (11535004, 11375086, 11120101005, 11175085 and 11235001), 973 Nation Major State Basic Research and Development of China (2013CB834400) and Science and Technology Development Fund of Macau (020/2014/A1 and 039/2013/A2)

The Fundamental Neutron Physics Beamline at the Spallation Neutron Source.

PubMed

Greene, Geoffrey; Cianciolo, Vince; Koehler, Paul; Allen, Richard; Snow, William Michael; Huffman, Paul; Gould, Chris; Bowman, David; Cooper, Martin; Doyle, John

2005-01-01

The Spallation Neutron Source (SNS), currently under construction at Oak Ridge National Laboratory with an anticipated start-up in early 2006, will provide the most intense pulsed beams of cold neutrons in the world. At a projected power of 1.4 MW, the time averaged fluxes and fluences of the SNS will approach those of high flux reactors. One of the flight paths on the cold, coupled moderator will be devoted to fundamental neutron physics. The fundamental neutron physics beamline is anticipated to include two beam-lines; a broad band cold beam, and a monochromatic beam of 0.89 nm neutrons for ultracold neutron (UCN) experiments. The fundamental neutron physics beamline will be operated as a user facility with experiment selection based on a peer reviewed proposal process. An initial program of five experiments in neutron decay, hadronic weak interaction and time reversal symmetry violation have been proposed.

NEUTRONIC REACTOR DESIGN TO REDUCE NEUTRON LOSS

DOEpatents

Mills, F.T.

1961-05-01

A nuclear reactor construction is described in which an unmoderated layer of the fissionable material is inserted between the moderated portion of the reactor core and the core container steel wall which is surrounded by successive layers of pure fertile material and fertile material having moderator. The unmoderated layer of the fissionable material will insure that a greater portion of fast neutrons will pass through the steel wall than would thermal neutrons. As the steel has a smaller capture cross-section for the fast neutrons, then greater numbers of the neutrons will pass into the blanket thereby increasing the over-all efficiency of the reactor.

Neutronic Reactor Design to Reduce Neutron Loss

DOEpatents

Miles, F. T.

1961-05-01

A nuclear reactor construction is described in which an unmoderated layer of the fissionable material is inserted between the moderated portion of the reactor core and the core container steel wall. The wall is surrounded by successive layers of pure fertile material and moderator containing fertile material. The unmoderated layer of the fissionable material will insure that a greater portion of fast neutrons will pass through the steel wall than would thermal neutrons. Since the steel has a smaller capture cross section for the fast neutrons, greater nunnbers of neutrons will pass into the blanket, thereby increasing the over-all efficiency of the reactor. (AEC)

Neutron Capture Rates and the r-Process Abundance Pattern in Shocked Neutrino-Driven Winds

NASA Astrophysics Data System (ADS)

Barringer, Daniel; Surman, Rebecca

2009-10-01

The r-process is an important process in nucleosynthesis in which nuclei will undergo rapid neutron captures. Models of the r-process require nuclear data such as neutron capture rates for thousands of individual nuclei, many of which lie far from stability. Among the potential sites for the r-process, and the one that we investigate, is the shocked neutrino-driven wind in core-collapse supernovae. Here we examine the importance of the neutron capture rates of specific, individual nuclei in the second r-process abundance peak occurring at A ˜ 130 for a range of parameterized neutrino-driven wind trajectories. Of specific interest are the nuclei whose capture rates affect the abundances of nuclei outside of the A ˜ 130 peak. We found that increasing the neutron capture rate for a number of nuclei including ^135In, ^132Sn, ^133Sb, ^137Sb, and ^136Te can produce changes in the resulting abundance pattern of up to 13%.

A distributed network of low-cost continuous reading sensors to measure spatiotemporal variations of PM2.5 in Xi'an, China.

PubMed

Gao, Meiling; Cao, Junji; Seto, Edmund

2015-04-01

Fine particulate matter (PM2.5) is a growing public health concern especially in industrializing countries but existing monitoring networks are unable to properly characterize human exposures due to low resolution spatiotemporal data. Low-cost portable monitors can supplement existing networks in both developed and industrializing regions to increase density of sites and data. This study tests the performance of a low-cost sensor in high concentration urban environments. Seven Portable University of Washington Particle (PUWP) monitors were calibrated with optical and gravimetric PM2.5 reference monitors in Xi'an, China in December 2013. Pairwise correlations between the raw PUWP and the reference monitors were high (R(2) = 0.86-0.89). PUWP monitors were also simultaneously deployed at eight sites across Xi'an alongside gravimetric PM2.5 monitors (R(2) = 0.53). The PUWP monitors were able to identify the High-technology Zone site as a potential PM2.5 hotspot with sustained high concentrations compared to the city average throughout the day. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Thermal neutron detection system

DOEpatents

Peurrung, Anthony J.; Stromswold, David C.

2000-01-01

According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.

Neutron detector

DOEpatents

Stephan, Andrew C [Knoxville, TN; Jardret,; Vincent, D [Powell, TN

2011-04-05

A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

Radii of neutron drops probed via the neutron skin thickness of nuclei

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

Zhao, P. W.; Gandolfi, S.

Multineutron systems are crucial to understanding the physics of neutron-rich nuclei and neutron stars. Neutron drops, neutrons confined in an external field, are investigated systematically in both nonrelativistic and relativistic density functional theories and with ab initio calculations. Here, we demonstrate a new strong linear correlation, which is universal in the realm of mean-field models, between the rms radii of neutron drops and the neutron skin thickness of 208 Pb and 48 Ca , i.e., the difference between the neutron and proton rms radii of a nucleus. This correlation can be used to deduce the radii of neutron drops frommore » the measured neutron skin thickness in a model-independent way, and the radii obtained for neutron drops can provide a useful constraint for realistic three-neutron forces, due to its high quality. Furthermore, we present a new correlation between the slope L of the symmetry energy and the radii of neutron drops, and provide the first validation of such a correlation by using density-functional models and ab initio calculations. These newly established correlations, together with more precise measurements of the neutron skin thicknesses of 208 Pb and 48 Ca and/or accurate determinations of L , will have an enduring impact on the understanding of multineutron interactions, neutron-rich nuclei, neutron stars, etc.« less

Radii of neutron drops probed via the neutron skin thickness of nuclei

DOE PAGES

Zhao, P. W.; Gandolfi, S.

2016-10-10

Multineutron systems are crucial to understanding the physics of neutron-rich nuclei and neutron stars. Neutron drops, neutrons confined in an external field, are investigated systematically in both nonrelativistic and relativistic density functional theories and with ab initio calculations. Here, we demonstrate a new strong linear correlation, which is universal in the realm of mean-field models, between the rms radii of neutron drops and the neutron skin thickness of 208 Pb and 48 Ca , i.e., the difference between the neutron and proton rms radii of a nucleus. This correlation can be used to deduce the radii of neutron drops frommore » the measured neutron skin thickness in a model-independent way, and the radii obtained for neutron drops can provide a useful constraint for realistic three-neutron forces, due to its high quality. Furthermore, we present a new correlation between the slope L of the symmetry energy and the radii of neutron drops, and provide the first validation of such a correlation by using density-functional models and ab initio calculations. These newly established correlations, together with more precise measurements of the neutron skin thicknesses of 208 Pb and 48 Ca and/or accurate determinations of L , will have an enduring impact on the understanding of multineutron interactions, neutron-rich nuclei, neutron stars, etc.« less

Neutron collimator design of neutron radiography based on the BNCT facility

NASA Astrophysics Data System (ADS)

Yang, Xiao-Peng; Yu, Bo-Xiang; Li, Yi-Guo; Peng, Dan; Lu, Jin; Zhang, Gao-Long; Zhao, Hang; Zhang, Ai-Wu; Li, Chun-Yang; Liu, Wan-Jin; Hu, Tao; Lü, Jun-Guang

2014-02-01

For the research of CCD neutron radiography, a neutron collimator was designed based on the exit of thermal neutron of the Boron Neutron Capture Therapy (BNCT) reactor. Based on the Geant4 simulations, the preliminary choice of the size of the collimator was determined. The materials were selected according to the literature data. Then, a collimator was constructed and tested on site. The results of experiment and simulation show that the thermal neutron flux at the end of the neutron collimator is greater than 1.0×106 n/cm2/s, the maximum collimation ratio (L/D) is 58, the Cd-ratio(Mn) is 160 and the diameter of collimator end is 10 cm. This neutron collimator is considered to be applicable for neutron radiography.

Microfabrication of a gadolinium-derived solid-state sensor for thermal neutrons

PubMed Central

Achyuthan, Komandoor E.; Allen, Matthew; Denton, Michele L. B.; Siegal, Michael P.; Manginell, Ronald P.

2017-01-01

Abstract Neutron sensing is critical in civilian and military applications. Conventional neutron sensors are limited by size, weight, cost, portability and helium supply. Here the microfabrication of gadolinium (Gd) conversion material–based heterojunction diodes for detecting thermal neutrons using electrical signals produced by internal conversion electrons (ICEs) is described. Films with negligible stress were produced at the tensile-compressive crossover point, enabling Gd coatings of any desired thickness by controlling the radiofrequency sputtering power and using the zero-point near p(Ar) of 50 mTorr at 100 W. Post-deposition Gd oxidation–induced spallation was eliminated by growing a residual stress-free 50 nm neodymium-doped aluminum cap layer atop Gd. The resultant coatings were stable for at least 6 years, demonstrating excellent stability and product shelf-life. Depositing Gd directly on the diode surface eliminated the air gap, leading to a 200-fold increase in electron capture efficiency and facilitating monolithic microfabrication. The conversion electron spectrum was dominated by ICEs with energies of 72, 132 and 174 keV. Results are reported for neutron reflection and moderation by polyethylene for enhanced sensitivity, and γ- and X-ray elimination for improved specificity. The optimal Gd thickness was 10.4 μm for a 300 μm-thick partially depleted diode of 300 mm2 active surface area. Fast detection (within 10 min) at a neutron source-to-diode distance of 11.7 cm was achieved with this configuration. All ICE energies along with γ-ray and Kα,β X-rays were modeled to emphasize correlations between experiment and theory. Semi-conductor thermal neutron detectors offer advantages for field-sensing of radioactive neutron sources. PMID:28369631

ISOLEUCINE AND VALINE METABOLISM IN ESCHERICHIA COLI XI. K-12

PubMed Central

Leavitt, Richard I.; Umbarger, H. E.

1962-01-01

Leavitt, Richard I. (Harvard Medical School, Boston, Mass.) and H. E. Umbarger. Isoleucine and valine metabolism in Escherichia coli. XI. Valine inhibition of the growth of Escherichia coli strain K-12. J. Bacteriol. 83:624–630. 1962.—The inhibition of the growth of Escherichia coli strain K-12 by valine was shown to be due to the sensitivity of the acetohydroxybutyrate-forming system to valine. It was demonstrated that both E. coli strain W, a strain whose growth is unaffected by valine, and a valine-resistant mutant of strain K-12 have acetolactate- and acetohydroxybutyrate-forming systems which are less sensitive to valine than that of strain K-12. It was further shown that α-aminobutyrate accumulates in the culture fluid of the valine-sensitive strain when incubated in the presence of valine. The levels of valine in the “free amino acid pool” were examined and found to be related to the differences in valine sensitivity of the acetolactate-forming systems of the three strains. PMID:14463257

Bis(pinacolato)diboron as an additive for the detection of thermal neutrons in plastic scintillators

NASA Astrophysics Data System (ADS)

Mahl, Adam; Yemam, Henok A.; Stuntz, John; Remedes, Tyler; Sellinger, Alan; Greife, Uwe

2016-04-01

A readily available and inexpensive boron compound was tested as an additive for the detection of thermal neutrons in plastic scintillators. Bis(pinacolato)diboron (B2Pin2) was determined to be a compatible boron source (8.51 wt% boron, 1.70 wt% 10B) in poly(vinyltoluene) based matrices. Plastic scintillator blends of 1-20 wt% 2,5-diphenyloxazole (PPO), 0.1 wt% 1,4-bis(5-phenyloxazol-2-yl) benzene (POPOP) and 1-15 wt% B2Pin2 were prepared that provided optical clarity, good mechanical properties, and the capability of thermal neutron detection. Independent of B2Pin2 concentration, strong 10B neutron capture signals around 90 keVee were observed at essentially constant light output. Increasing PPO concentration allowed for the use of pulse shape discrimination (PSD) in both fast and thermal neutron detection. High PPO concentrations appear to cause additional alpha quenching that affected the 10B neutron capture signal. Aging effects after storage in air for several months were observed, which led to degradation of performance and in some samples of mechanical stability.

The extent and nature of television food advertising to children in Xi'an, China.

PubMed

Li, Danyang; Wang, Ting; Cheng, Yue; Zhang, Min; Yang, Xue; Zhu, Zhonghai; Liu, Danli; Yang, Wenfang; Zeng, Lingxia

2016-08-11

To explore the extent and nature of television food advertising especially unhealthy food advertising to primary school children in Xi'an, China. Television data were recorded for 2 weekdays and 2 weekend days between 6:00 and 22:00 during May and June in 2012 from a total of five television channels most popular with children in Xi'an. Pearson χ (2) tests and logistic regression were applied to determine differences in the proportion of healthy food, unhealthy food and miscellaneous food advertisements for different channels, programs, dates, viewing periods and the use of persuasive marketing tactics. Of the 5527 advertisements transcribed, 25.5 % were for food, among which 48.1 % were considered to be unhealthy. The frequency of food advertisements was 6 per hour per channel, including 3 unhealthy food advertisements. Compared with healthy and miscellaneous food advertisements, more unhealthy food advertisements were shown during afternoon, weekends and children's non-peak viewing times as well as on children's television channels, central television channels and non-children's programmes. Unhealthy foods contributed the highest proportion of all food advertisements containing promotional characters (51.7 %) and premium offers (59.1 %). Both promotional characters and premium offers appeared more on non-children's television channels. The majority of food advertisements were for unhealthy food. More unhealthy food ads were shown in children's non-peak time and afternoon as well as non-children's channels. More children-oriented persuasive marketing tactics were used in unhealthy food ads especially in non-children's channels. Therefore, intervening in the entrance of unhealthy foods into the market and establishing regulations related to food advertising especially unhealthy food advertisements are important strategies to prevent children's exposure to unhealthy food and childhood obesity.

Comparisons of monthly mean cosmic ray counting rates observes from worldwide network of neutron monitors

NASA Technical Reports Server (NTRS)

Ryu, J. Y.; Wada, M.

1985-01-01

In order to examine the stability of neutron monitor observation, each of the monthly average counting rates of a neutron monitors is correlated to those of Kiel neutron monitor. The regression coefficients thus obtained are compared with the coupling coefficients of isotropic intensity radiation. The results of the comparisons for five year periods during 1963 to 1982, and for whole period are given. The variation spectrum with a single power law with an exponent of -0.75 up to 50 GV is not so unsatisfactory one. More than one half of the stations show correlations with the coefficient greater than 0.9. Some stations have shifted the level of mean counting rates by changing the instrumental characteristics which can be adjusted.

Investigation of the response of a neutron-Hand monitor dedicated to the powder diffractometer at CENM-Maamora

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

Messous, M.Y.; Belhorma, B.; Labrim, H.

2015-07-01

Neutrons are used for the study of condensed matter. A neutron beam can indeed easily penetrate the solid material and undergo diffraction phenomena. Analysis of the diffused neutrons allows studying the atomic structure of crossed material. Their neutral electric charge makes them nondestructive probe of a great interest. In general, the size of the powder samples is very small and therefore the centering of the beam on these is very crucial. It is in this context we proceed to test a portable neutron monitor for centering and checking beam leak around the shielding to be installed around the diffractometer inmore » TRIGA Mark II of CENM. It's consisting of a scintillation neutron detector NE426 ({sup 6}LiF + ZnS (Ag)) with electronic module and data acquisition system. The effect of radiation from radioactive neutrons source {sup 252}Cf is shown. Sensitivity and differential linearity are also performed. This study indicates several advantages of this detector with very good detection sensitivity and excellent stability during the counting time. (authors)« less

Prevalence and Correlates of School Bullying Victimization in Xi'an, China.

PubMed

Zhu, Yuhong; Chan, Ko Ling

2015-01-01

This study used the data from a representative sample to estimate the prevalence of child bullying victimization in Xi'an, China. Data on social demographic information and the experiences of different types of bullying victimization were collected from a randomly selected sample with 3,175 middle school students aged 15-17 years by self-administrated questionnaires. t Test, χ2 test, and multiple logistic regression analyses were used to test group differences and examine the correlates of bullying victimization. Results show that 54.9% and 44.6% of Chinese children have been bullied in a lifetime and in the preceding year, respectively. Correlates for direct and relational bullying victimization includes male participants, father's lower education level, father's unemployment, having one or more siblings, smoking, depression, borderline personality trait, posttraumatic stress disorder, and from rural schools. Overall, the prevalence of child bullying victimization in China is substantial. The multiple correlates suggest prevention and intervention of bullying victimization in a holistic and comprehensive way.

The accelerator neutron source for boron neutron capture therapy

NASA Astrophysics Data System (ADS)

Kasatov, D.; Koshkarev, A.; Kuznetsov, A.; Makarov, A.; Ostreinov, Yu; Shchudlo, I.; Sorokin, I.; Sycheva, T.; Taskaev, S.; Zaidi, L.

2016-11-01

The accelerator based epithermal neutron source for Boron Neutron Capture Therapy (BNCT) is proposed, created and used in the Budker Institute of Nuclear Physics. In 2014, with the support of the Russian Science Foundation created the BNCT laboratory for the purpose to the end of 2016 get the neutron flux, suitable for BNCT. For getting 3 mA 2.3 MeV proton beam, was created a new type accelerator - tandem accelerator with vacuum isolation. On this moment, we have a stationary proton beam with 2.3 MeV and current 1.75 mA. Generation of neutrons is carried out by dropping proton beam on to lithium target as a result of threshold reaction 7Li(p,n)7Be. Established facility is a unique scientific installation. It provides a generating of neutron flux, including a monochromatic energy neutrons, gamma radiation, alpha-particles and positrons, and may be used by other research groups for carrying out scientific researches. The article describes an accelerator neutron source, presents and discusses the result of experiments and declares future plans.

α and 2 p 2 n emission in fast neutron-induced reactions on 60Ni

NASA Astrophysics Data System (ADS)

Fotiades, N.; Devlin, M.; Haight, R. C.; Nelson, R. O.; Kunieda, S.; Kawano, T.

2015-06-01

Background: The cross sections for populating the residual nucleus in the reaction ZAX(n,x) Z -2 A -4Y exhibit peaks as a function of incident neutron energy corresponding to the (n ,n'α ) reaction and, at higher energy, to the (n ,2 p 3 n ) reaction. The relative magnitudes of these peaks vary with the Z of the target nucleus. Purpose: Study fast neutron-induced reactions on 60Ni. Locate experimentally the nuclear charge region along the line of stability where the cross sections for α emission and for 2 p 2 n emission in fast neutron-induced reactions are comparable as a further test of reaction models. Methods: Data were taken by using the Germanium Array for Neutron-Induced Excitations. The broad-spectrum pulsed neutron beam of the Los Alamos Neutron Science Center's Weapons Neutron Research facility provided neutrons in the energy range from 1 to 250 MeV. The time-of-flight technique was used to determine the incident-neutron energies. Results: Absolute partial cross sections for production of seven discrete Fe γ rays populated in 60Ni (n ,α /2 p x n γ ) reactions with 2 ≤x ≤5 were measured for neutron energies 1 MeVneutron energies while discrepancies appear at higher neutron energies. The cross section for producing an isotope in fast neutron-induced reactions on stable targets via α emission at the peak of the (n ,α ) and (n ,n'α ) reactions is comparable to that for 2 p 2 n and 2 p 3 n emission at higher incident energies in the nuclear charge region around Fe.

Development of fast neutron radiography system based on portable neutron generator

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

Yi, Chia Jia, E-mail: gei-i-kani@hotmail.com; Nilsuwankosit, Sunchai, E-mail: sunchai.n@chula.ac.th

Due to the high installation cost, the safety concern and the immobility of the research reactors, the neutron radiography system based on portable neutron generator is proposed. Since the neutrons generated from a portable neutron generator are mostly the fast neutrons, the system is emphasized on using the fast neutrons for the purpose of conducting the radiography. In order to suppress the influence of X-ray produced by the neutron generator, a combination of a shielding material sandwiched between two identical imaging plates is used. A binary XOR operation is then applied for combining the information from the imaging plates. Themore » raw images obtained confirm that the X-ray really has a large effect and that XOR operation can help enhance the effect of the neutrons.« less

VizieR Online Data Catalog: xi Tau UBV and MOST light curves (Nemravova+, 2016)

NASA Astrophysics Data System (ADS)

Nemravova, J. A.; Harmanec, P.; Broz, M.; Vokrouhlicky, D.; Mourard, D.; Hummel, C. A.; Cameron, C.; Matthews, J. M.; Bolton, C. T.; Bozic, H.; Chini, R.; Dembsky, T.; Engle, S.; Farrington, C.; Grunhut, J. H.; Guenther, D. B.; Guinan, E. F.; Korcakova, D.; Koubsky, P.; Kiek, R.; Kuschnig, R.; Mayer, P.; McCook, G. P.; Moffat, A. F. J.; Nardetto, N.; Pra, A.; Ribeiro, J.; Rowe, J.; Rucinski, S.; Skoda, P.; Slechta, M.; Tallon-Bosc, I.; Votruba, V.; Weiss, W. W.; Wolf, M.; Zasche, P.; Zavala, R. T.

2016-05-01

We present reduced observations, that were used in study of the quadruple hierarchical binary xi Tauri. The observational material consists of radial-velocity measurements (tabled1.dat), photometric measurements in the MOST filter (tabled2.dat), and Johnson's U (tabled3.dat), B (tabled4.dat), and V (tabled5.dat), and spectro-interferometric measurements represented by squared visibility moduli (tabled6.dat), and closure phases (tabled7.dat). The~description of the reductions is given in Appendices A (the spectroscopy), B (the photometry), and C (the spectro-interferometry). The procedure of radial-velocity measuring is described in Sect. 3.1. Headers of Tables D.1-D.7 published electronically are also given in Appendix D. (7 data files).

Development of high flux thermal neutron generator for neutron activation analysis

NASA Astrophysics Data System (ADS)

Vainionpaa, Jaakko H.; Chen, Allan X.; Piestrup, Melvin A.; Gary, Charles K.; Jones, Glenn; Pantell, Richard H.

2015-05-01

The new model DD110MB neutron generator from Adelphi Technology produces thermal (<0.5 eV) neutron flux that is normally achieved in a nuclear reactor or larger accelerator based systems. Thermal neutron fluxes of 3-5 · 107 n/cm2/s are measured. This flux is achieved using four ion beams arranged concentrically around a target chamber containing a compact moderator with a central sample cylinder. Fast neutron yield of ∼2 · 1010 n/s is created at the titanium surface of the target chamber. The thickness and material of the moderator is selected to maximize the thermal neutron flux at the center. The 2.5 MeV neutrons are quickly thermalized to energies below 0.5 eV and concentrated at the sample cylinder. The maximum flux of thermal neutrons at the target is achieved when approximately half of the neutrons at the sample area are thermalized. In this paper we present simulation results used to characterize performance of the neutron generator. The neutron flux can be used for neutron activation analysis (NAA) prompt gamma neutron activation analysis (PGNAA) for determining the concentrations of elements in many materials. Another envisioned use of the generator is production of radioactive isotopes. DD110MB is small enough for modest-sized laboratories and universities. Compared to nuclear reactors the DD110MB produces comparable thermal flux but provides reduced administrative and safety requirements and it can be run in pulsed mode, which is beneficial in many neutron activation techniques.

Neutron therapy of cancer

NASA Technical Reports Server (NTRS)

Frigerio, N. A.; Nellans, H. N.; Shaw, M. J.

1969-01-01

Reports relate applications of neutrons to the problem of cancer therapy. The biochemical and biophysical aspects of fast-neutron therapy, neutron-capture and neutron-conversion therapy with intermediate-range neutrons are presented. Also included is a computer program for neutron-gamma radiobiology.

Neutron capture therapy with deep tissue penetration using capillary neutron focusing

DOEpatents

Peurrung, Anthony J.

1997-01-01

An improved method for delivering thermal neutrons to a subsurface cancer or tumor which has been first doped with a dopant having a high cross section for neutron capture. The improvement is the use of a guide tube in cooperation with a capillary neutron focusing apparatus, or neutron focusing lens, for directing neutrons to the tumor, and thereby avoiding damage to surrounding tissue.

Neutron dosimetry

DOEpatents

Quinby, Thomas C.

1976-07-27

A method of measuring neutron radiation within a nuclear reactor is provided. A sintered oxide wire is disposed within the reactor and exposed to neutron radiation. The induced radioactivity is measured to provide an indication of the neutron energy and flux within the reactor.

Measuring neutron spectra in radiotherapy using the nested neutron spectrometer.

PubMed

Maglieri, Robert; Licea, Angel; Evans, Michael; Seuntjens, Jan; Kildea, John

2015-11-01

Out-of-field neutron doses resulting from photonuclear interactions in the head of a linear accelerator pose an iatrogenic risk to patients and an occupational risk to personnel during radiotherapy. To quantify neutron production, in-room measurements have traditionally been carried out using Bonner sphere systems (BSS) with activation foils and TLDs. In this work, a recently developed active detector, the nested neutron spectrometer (NNS), was tested in radiotherapy bunkers. The NNS is designed for easy handling and is more practical than the traditional BSS. Operated in current-mode, the problem of pulse pileup due to high dose-rates is overcome by measuring current, similar to an ionization chamber. In a bunker housing a Varian Clinac 21EX, the performance of the NNS was evaluated in terms of reproducibility, linearity, and dose-rate effects. Using a custom maximum-likelihood expectation-maximization algorithm, measured neutron spectra at various locations inside the bunker were then compared to Monte Carlo simulations of an identical setup. In terms of dose, neutron ambient dose equivalents were calculated from the measured spectra and compared to bubble detector neutron dose equivalent measurements. The NNS-measured spectra for neutrons at various locations in a treatment room were found to be consistent with expectations for both relative shape and absolute magnitude. Neutron fluence-rate decreased with distance from the source and the shape of the spectrum changed from a dominant fast neutron peak near the Linac head to a dominant thermal neutron peak in the moderating conditions of the maze. Monte Carlo data and NNS-measured spectra agreed within 30% at all locations except in the maze where the deviation was a maximum of 40%. Neutron ambient dose equivalents calculated from the authors' measured spectra were consistent (one standard deviation) with bubble detector measurements in the treatment room. The NNS may be used to reliably measure the neutron

Atmospheric neutrons

NASA Technical Reports Server (NTRS)

Korff, S. A.; Mendell, R. B.; Merker, M.; Light, E. S.; Verschell, H. J.; Sandie, W. S.

1979-01-01

Contributions to fast neutron measurements in the atmosphere are outlined. The results of a calculation to determine the production, distribution and final disappearance of atmospheric neutrons over the entire spectrum are presented. An attempt is made to answer questions that relate to processes such as neutron escape from the atmosphere and C-14 production. In addition, since variations of secondary neutrons can be related to variations in the primary radiation, comment on the modulation of both radiation components is made.

High-Pressure Neutron Diffraction Studies for Materials Sciences and Energy Sciences

NASA Astrophysics Data System (ADS)

Zhao, Y.; Los Alamos High Pressure Materials Research Team

2013-05-01

The development of neutron diffraction under extreme pressure (P) and temperature (T) conditions is highly valuable to condensed matter physics, crystal chemistry, materials sciences, as well as earth and planetary sciences. We have incorporated a 500-ton press TAP-98 into the HiPPO diffractometer at LANSCE to conduct in situ high P-T neutron diffraction experiments. We have worked out a large gem-crystal anvil cell, ZAP, to conduct neutron diffraction experiments at high-P and low-T. The ZAP cell can be used to integrate multiple experimental techniques such as neutron diffraction, laser spectroscopy, and ultrasonic interferometery. Recently, we have developed high-P low-T gas/fluid cells in conjunction with neutron diffraction and inelastic neutron scattering instruments. These techniques enable in-situ and real-time examination of gas uptake/release processes and allow high-resolution time-dependent determination of changes in crystal structure and related reaction kinetics. We have successfully used these techniques to study the equation of state, structural phase transition, and thermo-mechanical properties of metals, ceramics, and minerals. We have conducted researches on the formation of methane and hydrogen clathrates, and hydrogen adsorption of the inclusion compounds such as the recently discovered metal-organic frameworks (MOFs). The aim of our research is to accurately map phase diagram, lattice parameters, thermal parameters, bond lengths, bond angles, neighboring atomic environments, and phase stability in P-T-X space. We are currently developing further high P-T technology with a new "true" triaxial loading press, TAP_6x, to compress cubic sample package to achieve pressures up to 20 GPa and temperatures up to 2000 K in routine experiments. The implementation of TAP_6x300 with high-pressure neutron beamlines is underway for simultaneous high P-T neutron diffraction, ultrasonic, calorimetry, radiography, and tomography studies. Studies based on high

Neutron multiplicity ,easurements With 3He alternative: Straw neutron detectors

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

Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Meade, John A.

Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as “ship effect”) and to the complicated nature of the neutron scattering in that environment. In this study, a prototype neutron detector was built using 10B as the converter in a special form factor called “straws” that would address the above problems by looking into the details of multiplicity distributions ofmore » neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used 10B (in the form of enriched boron carbide: 10B 4C) for neutron detection instead of 3He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics, and developed a data acquisition (DAQ) system to collect

Neutron multiplicity measurements with 3He alternative: Straw neutron detectors

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

Mukhopadhyay, Sanjoy; Wolff, Ronald; Detwiler, Ryan

Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as ‘‘ship effect ’’) and to the complicated nature of the neutron scattering in that environment. A prototype neutron detector was built using 10B as the converter in a special form factor called ‘‘straws’’ that would address the above problems by looking into the details of multiplicity distributions of neutrons originatingmore » from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used 10B (in the form of enriched boron carbide: 10B 4C) for neutron detection instead of 3He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics, and developed a data acquisition (DAQ) system to collect

Neutron multiplicity ,easurements With 3He alternative: Straw neutron detectors

DOE PAGES

Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Meade, John A.; ...

2015-01-27

Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as “ship effect”) and to the complicated nature of the neutron scattering in that environment. In this study, a prototype neutron detector was built using 10B as the converter in a special form factor called “straws” that would address the above problems by looking into the details of multiplicity distributions ofmore » neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used 10B (in the form of enriched boron carbide: 10B 4C) for neutron detection instead of 3He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics, and developed a data acquisition (DAQ) system to collect

Neutron capture therapy with deep tissue penetration using capillary neutron focusing

DOEpatents

Peurrung, A.J.

1997-08-19

An improved method is disclosed for delivering thermal neutrons to a subsurface cancer or tumor which has been first doped with a dopant having a high cross section for neutron capture. The improvement is the use of a guide tube in cooperation with a capillary neutron focusing apparatus, or neutron focusing lens, for directing neutrons to the tumor, and thereby avoiding damage to surrounding tissue. 1 fig.

Astrophysical quests for neutron capture data of unstable nuclei

NASA Astrophysics Data System (ADS)

Käppeler, F.

2016-11-01

The abundances of the chemical elements heavier than iron can be attributed in about equal parts to the r and to the s process, which are taking place in supernova explosions and during the He and C burning phases of stellar evolution, respectively. So far, quantitative studies on the extremely short-lived neutron-rich nuclei constituting the ( n, γ) network of the r process are out of reach. On the contrary, the situation for the s -process is far advanced, as the reaction path of the s process from 12C to the Pb/Bi region is located within the valley of stability. Accordingly, a comprehensive database of experimental ( n, γ) cross sections has been established. While for many stable isotopes the necessary accuracy is still to be reached, reliable cross sections for the involved unstable isotopes are almost completely missing. Because of the intrinsic γ background of radioactive samples, successful time-of-flight measurements are depending on intense pulsed neutron sources. Such data are fundamental for our understanding of branchings in the s -process reaction path, which carry important model-independent information on neutron flux and temperature in the deep stellar interior.

Neutron streak camera

DOEpatents

Wang, C.L.

1981-05-14

Apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon.

Neutron streak camera

DOEpatents

Wang, Ching L.

1983-09-13

Apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon.

Neutron streak camera

DOEpatents

Wang, C.L.

1983-09-13

Disclosed is an apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon. 4 figs.

Neurotic disorders of general medical outpatients in Xi'an, China: knowledge, attitudes, and help-seeking preferences.

PubMed

Ni, Chunping; Ma, Lihua; Wang, Bo; Yan, Yongping; Huang, Yueqin; Wallen, Gwenyth R; Li, Lu; Lang, Hongjuan; Hua, Qianzhen

2014-08-01

This study assessed knowledge of neurotic disorders, and attitudes and preferences toward professional help and treatment for them, among general medical outpatients in general hospitals in Xi'an, China. General medical outpatients (N=372) from general hospitals in China were recruited by using a stratified cluster sampling method between June and September 2010. In face-to-face interviews, participants age 16 years or older were assessed for their knowledge, attitudes, and help-seeking preferences in regard to neurotic disorders (obsessive-compulsive disorder, social phobia, and panic disorder). Demographic data were also collected. Lack of insight into neurotic disorders was common among medical outpatients in general hospitals of Xi'an, China. Twenty-four percent to 58% of the outpatients had some knowledge of the symptoms and treatment of neurotic disorders. Only 11% of the outpatients would reveal to others that they or a family member suffered from neurotic disorders. When faced with the problem of neurotic disorders, the preference of the respondents was to visit a psychiatrist in a general hospital (44%), and only 17% would visit a physician in a psychiatric hospital. Major ways for the outpatients to obtain knowledge regarding neurotic disorders were via radio and television (36%), and only 18%-23% of outpatients obtained knowledge about neurotic disorders through printed public health materials and by attending lectures. Study results underscore the need for information campaigns aimed at improving the mental health literacy of general medical outpatients. Such campaigns must consider culturally relevant beliefs to facilitate the development of specific educational programs.

Optical properties and possible sources of brown carbon in PM2.5 over Xi'an, China

NASA Astrophysics Data System (ADS)

Shen, Zhenxing; Zhang, Qian; Cao, Junji; Zhang, Leiming; Lei, Yali; Huang, Yu; Huang, R.-J.; Gao, Jinjin; Zhao, Zhuzi; Zhu, Chongshu; Yin, Xiuli; Zheng, Chunli; Xu, Hongmei; Liu, Suixin

2017-02-01

To quantify optical and chemical properties of PM2.5 brown carbon (BrC) in Xi'an, 58 high-volume ambient PM2.5 samples were collected during 2 November 2009 to 13 October 2010. Mass concentrations of chemical components were determined, including water-soluble ions, water-soluble organic carbon, levoglucosan, organic carbon (OC), and element carbon (EC). BrC, as an unidentified and wavelength-dependent organic compound, was also measured from water-soluble carbon (WSOC) at 340 nm using UV-vis spectrometer. The wavelength-dependent absorption coefficient (babs) and mass absorption coefficient (MAC) were much abundant at 340 nm, and the high Absorption Ångström coefficient (AAC) values were observed around 5.4, corresponding to the existence of BrC in ambient PM2.5, especially in winter. Good correlations (R > 0.60) between babs and biomass burning markers, such as levoglucosan and K+, in winter indicated significant amounts of primary BrC from biomass burning emissions. Secondary organic carbon BrC (SOCsbnd BrC) was more abundant in winter than in summer. SOCsbnd BrC in winter was mainly fresh SOC formed from aqueous phase reactions while in summer, aged SOC from photo-chemical formation. Source profiles of BrC optical parameters were detected, which verified sources of BrC from biomass burning and coal burning emissions in areas surrounding Xi'an. The rapidly decreasing babs-340nm values from biomass burning smoldering to straw pellet burning suggested that burning straw pellet instead of burning straw directly is an effective measure for reducing BrC emissions.

The possible use of a spallation neutron source for neutron capture therapy with epithermal neutrons.

PubMed

Grusell, E; Condé, H; Larsson, B; Rönnqvist, T; Sornsuntisook, O; Crawford, J; Reist, H; Dahl, B; Sjöstrand, N G; Russel, G

1990-01-01

Spallation is induced in a heavy material by 72-MeV protons. The resulting neutrons can be characterized by an evaporation spectrum with a peak energy of less than 2 MeV. The neutrons are moderated in two steps: first in iron and then in carbon. Results from neutron fluence measurements in a perspex phantom placed close to the moderator are presented. Monte Carlo calculations of neutron fluence in a water phantom are also presented under some chosen configurations of spallation source and moderator. The calculations and measurements are in good agreement and show that, for proton currents of less than 0.5 mA, useful thermal-neutron fluences are attainable in the depth of the brain. However, the dose contribution from the unavoidable gamma background component has not been included in the present investigation.

Neutron capture therapies

DOEpatents

Yanch, Jacquelyn C.; Shefer, Ruth E.; Klinkowstein, Robert E.

1999-01-01

In one embodiment there is provided an application of the .sup.10 B(n,.alpha.).sup.7 Li nuclear reaction or other neutron capture reactions for the treatment of rheumatoid arthritis. This application, called Boron Neutron Capture Synovectomy (BNCS), requires substantially altered demands on neutron beam design than for instance treatment of deep seated tumors. Considerations for neutron beam design for the treatment of arthritic joints via BNCS are provided for, and comparisons with the design requirements for Boron Neutron Capture Therapy (BNCT) of tumors are made. In addition, exemplary moderator/reflector assemblies are provided which produce intense, high-quality neutron beams based on (p,n) accelerator-based reactions. In another embodiment there is provided the use of deuteron-based charged particle reactions to be used as sources for epithermal or thermal neutron beams for neutron capture therapies. Many d,n reactions (e.g. using deuterium, tritium or beryllium targets) are very prolific at relatively low deuteron energies.

Pulsed-neutron monochromator

DOEpatents

Mook, H.A. Jr.

1984-01-01

In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The waves are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

Pulsed-neutron monochromator

DOEpatents

Mook, Jr., Herbert A.

1985-01-01

In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The wave are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

Microscale spatial distribution and health assessment of PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) at nine communities in Xi'an, China.

PubMed

Xu, Hongmei; Ho, Steven Sai Hang; Gao, Meiling; Cao, Junji; Guinot, Benjamin; Ho, Kin Fai; Long, Xin; Wang, Jingzhi; Shen, Zhenxing; Liu, Suixin; Zheng, Chunli; Zhang, Qian

2016-11-01

Spatial variability of polycyclic aromatic hydrocarbons (PAHs) associated with fine particulate matter (PM 2.5 ) was investigated in Xi'an, China, in summer of 2013. Sixteen priority PAHs were quantified in 24-h integrated air samples collected simultaneously at nine urban and suburban communities. The total quantified PAHs mass concentrations ranged from 32.4 to 104.7 ng m -3 , with an average value of 57.1 ± 23.0 ng m -3 . PAHs were observed higher concentrations at suburban communities (average: 86.3 ng m -3 ) than at urban ones (average: 48.8 ng m -3 ) due to a better enforcement of the pollution control policies at the urban scale, and meanwhile the disorganized management of motor vehicles and massive building constructions in the suburbs. Elevated PAH levels were observed in the industrialized regions (west and northwest of Xi'an) from Kriging interpolation analysis. Satellite-based visual interpretations of land use were also applied for the supporting the spatial distribution of PAHs among the communities. The average benzo[a]pyrene-equivalent toxicity (Σ[BaP] eq ) at the nine communities was 6.9 ± 2.2 ng m -3 during the sampling period, showing a generally similar spatial distribution to PAHs levels. On average, the excess inhalation lifetime cancer risk derived from Σ[BaP] eq indicated that eight persons per million of community residents would develop cancer due to PM 2.5 -bound PAHs exposure in Xi'an. The great in-city spatial variability of PAHs confirmed the importance of multiple points sampling to conduct exposure health risk assessment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Stability and accuracy of 3D neutron transport simulations using the 2D/1D method in MPACT

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

Collins, Benjamin, E-mail: collinsbs@ornl.gov; Stimpson, Shane, E-mail: stimpsonsg@ornl.gov; Kelley, Blake W., E-mail: kelleybl@umich.edu

2016-12-01

A consistent “2D/1D” neutron transport method is derived from the 3D Boltzmann transport equation, to calculate fuel-pin-resolved neutron fluxes for realistic full-core Pressurized Water Reactor (PWR) problems. The 2D/1D method employs the Method of Characteristics to discretize the radial variables and a lower order transport solution to discretize the axial variable. This paper describes the theory of the 2D/1D method and its implementation in the MPACT code, which has become the whole-core deterministic neutron transport solver for the Consortium for Advanced Simulations of Light Water Reactors (CASL) core simulator VERA-CS. Several applications have been performed on both leadership-class and industry-classmore » computing clusters. Results are presented for whole-core solutions of the Watts Bar Nuclear Power Station Unit 1 and compared to both continuous-energy Monte Carlo results and plant data.« less

Stability and accuracy of 3D neutron transport simulations using the 2D/1D method in MPACT

DOE PAGES

Collins, Benjamin; Stimpson, Shane; Kelley, Blake W.; ...

2016-08-25

We derived a consistent “2D/1D” neutron transport method from the 3D Boltzmann transport equation, to calculate fuel-pin-resolved neutron fluxes for realistic full-core Pressurized Water Reactor (PWR) problems. The 2D/1D method employs the Method of Characteristics to discretize the radial variables and a lower order transport solution to discretize the axial variable. Our paper describes the theory of the 2D/1D method and its implementation in the MPACT code, which has become the whole-core deterministic neutron transport solver for the Consortium for Advanced Simulations of Light Water Reactors (CASL) core simulator VERA-CS. We also performed several applications on both leadership-class and industry-classmore » computing clusters. Results are presented for whole-core solutions of the Watts Bar Nuclear Power Station Unit 1 and compared to both continuous-energy Monte Carlo results and plant data.« less

Odd-even parity splittings and octupole correlations in neutron-rich Ba isotopes

NASA Astrophysics Data System (ADS)

Fu, Y.; Wang, H.; Wang, L.-J.; Yao, J. M.

2018-02-01

The odd-even parity splittings in low-lying parity-doublet states of atomic nuclei with octupole correlations have usually been interpreted as rotational excitations on top of octupole vibration in the language of collective models. In this paper, we report a deep analysis of the odd-even parity splittings in the parity-doublet states of neutron-rich Ba isotopes around neutron number N =88 within a full microscopic framework of beyond-mean-field multireference covariant energy density functional theory. The dynamical correlations related to symmetry restoration and quadrupole-octupole shape fluctuation are taken into account with a generator coordinate method combined with parity, particle-number, and angular-momentum projections. We show that the behavior of odd-even parity splittings is governed by the interplay of rotation, quantum tunneling, and shape evolution. Similar to 224Ra, a picture of rotation-induced octupole shape stabilization in the positive-parity states is exhibited in the neutron-rich Ba isotopes.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

Neutron reflecting supermirror structure

DOEpatents

Wood, J.L.

1992-12-01

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. 2 figs.

Neutron reflecting supermirror structure

DOEpatents

Wood, James L.

1992-01-01

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources.

Microfabrication of a gadolinium-derived solid-state sensor for thermal neutrons

DOE PAGES

Pfeifer, Kent B.; Achyuthan, Komandoor E.; Allen, Matthew; ...

2017-03-25

Neutron sensing is critical in civilian and military applications. Conventional neutron sensors are limited by size, weight, cost, portability and helium supply. Here in this study, the microfabrication of gadolinium (Gd) conversion material–based heterojunction diodes for detecting thermal neutrons using electrical signals produced by internal conversion electrons (ICEs) is described. Films with negligible stress were produced at the tensile-compressive crossover point, enabling Gd coatings of any desired thickness by controlling the radiofrequency sputtering power and using the zero-point near p(Ar) of 50 mTorr at 100 W. Post-deposition Gd oxidation–induced spallation was eliminated by growing a residual stress-free 50 nm neodymium-dopedmore » aluminum cap layer atop Gd. The resultant coatings were stable for at least 6 years, demonstrating excellent stability and product shelf-life. Depositing Gd directly on the diode surface eliminated the air gap, leading to a 200-fold increase in electron capture efficiency and facilitating monolithic microfabrication. The conversion electron spectrum was dominated by ICEs with energies of 72, 132 and 174 keV. Results are reported for neutron reflection and moderation by polyethylene for enhanced sensitivity, and γ- and X-ray elimination for improved specificity. The optimal Gd thickness was 10.4 μm for a 300 μm-thick partially depleted diode of 300 mm 2 active surface area. Fast detection (within 10 min) at a neutron source-to-diode distance of 11.7 cm was achieved with this configuration. All ICE energies along with γ-ray and K α,β X-rays were modeled to emphasize correlations between experiment and theory. Semi-conductor thermal neutron detectors offer advantages for field-sensing of radioactive neutron sources.« less

Microfabrication of a gadolinium-derived solid-state sensor for thermal neutrons

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

Pfeifer, Kent B.; Achyuthan, Komandoor E.; Allen, Matthew

Neutron sensing is critical in civilian and military applications. Conventional neutron sensors are limited by size, weight, cost, portability and helium supply. Here in this study, the microfabrication of gadolinium (Gd) conversion material–based heterojunction diodes for detecting thermal neutrons using electrical signals produced by internal conversion electrons (ICEs) is described. Films with negligible stress were produced at the tensile-compressive crossover point, enabling Gd coatings of any desired thickness by controlling the radiofrequency sputtering power and using the zero-point near p(Ar) of 50 mTorr at 100 W. Post-deposition Gd oxidation–induced spallation was eliminated by growing a residual stress-free 50 nm neodymium-dopedmore » aluminum cap layer atop Gd. The resultant coatings were stable for at least 6 years, demonstrating excellent stability and product shelf-life. Depositing Gd directly on the diode surface eliminated the air gap, leading to a 200-fold increase in electron capture efficiency and facilitating monolithic microfabrication. The conversion electron spectrum was dominated by ICEs with energies of 72, 132 and 174 keV. Results are reported for neutron reflection and moderation by polyethylene for enhanced sensitivity, and γ- and X-ray elimination for improved specificity. The optimal Gd thickness was 10.4 μm for a 300 μm-thick partially depleted diode of 300 mm 2 active surface area. Fast detection (within 10 min) at a neutron source-to-diode distance of 11.7 cm was achieved with this configuration. All ICE energies along with γ-ray and K α,β X-rays were modeled to emphasize correlations between experiment and theory. Semi-conductor thermal neutron detectors offer advantages for field-sensing of radioactive neutron sources.« less

Binary and ternary ionic compounds in the outer crust of accreted neutron stars

NASA Astrophysics Data System (ADS)

Chamel, N.

2017-12-01

The outer crust of an accreted neutron star is thought to contain a large distribution of different nuclear species resulting from the burying of ashes of X-ray bursts and superbursts. By analysing the stability of multicomponent Coulomb crystals against phase separation, it is found that various binary and ternary ionic compounds could be formed.

Transverse beam stability measurement and analysis for the SNS accumulator ring

DOE PAGES

Xie, Zaipeng; Deibele, Craig; Schulte, Michael J.; ...

2015-07-01

In a Field-programmable gate array (FPGA) based transverse feedback damper system we implemented in the Spallation Neutron Source (SNS) accumulator ring with the intention to stabilize the electron-proton (e-p) instability in a frequency range from 1 MHz to 300 MHz. The transverse damper could also be used as a diagnostic tool by measuring the beam transfer function (BTF). An analysis of the BTF measurement provides the stability diagram for the production beam at SNS. Our paper describes the feedback damper system and its set-up as the BTF diagnostic tool. Experimental BTF results are presented and beam stability analysis is performedmore » based on the BTF measurements for the SNS accumulator ring.« less

Production of neutron-rich nuclei approaching r-process by gamma-induced fission of 238U at ELI-NP

NASA Astrophysics Data System (ADS)

Mei, Bo; Balabanski, Dimiter; Constantin, Paul; Anh Le, Tuan; Viet Cuong, Phan

2018-05-01

The investigation of neutron-rich exotic nuclei is crucial not only for nuclear physics but also for nuclear astrophysics. Experimentally, only few neutron-rich nuclei near the stability have been studied, however, most neutron-rich nuclei have not been measured due to their small production cross sections as well as short half-lives. At ELI-NP, gamma beams with high intensities will open new opportunities to investigate very neutron-rich fragments produced by photofission of 238U targets in a gas cell. Based on some simulations, a novel gas cell has been designed to produce, stop and extract 238U photofission fragments. The extraction time and efficiency of photofission fragments have been optimized by using SIMION simulations. According to these simulations, a high extraction efficiency and a short extraction time can be achieved for 238U photofission fragments in the gas cell, which will allow one to measure very neutron-rich fragments with short half-lives by using the IGISOL facility proposed at ELI-NP.

The "neutron channel design"—A method for gaining the desired neutrons

NASA Astrophysics Data System (ADS)

Hu, G.; Hu, H. S.; Wang, S.; Pan, Z. H.; Jia, Q. G.; Yan, M. F.

2016-12-01

The neutrons with desired parameters can be obtained after initial neutrons penetrating various structure and component of the material. A novel method, the "neutron channel design", is proposed in this investigation for gaining the desired neutrons. It is established by employing genetic algorithm (GA) combining with Monte Carlo software. This method is verified by obtaining 0.01eV to 1.0eV neutrons from the Compact Accelerator-driven Neutron Source (CANS). One layer polyethylene (PE) moderator was designed and installed behind the beryllium target in CANS. The simulations and the experiment for detection the neutrons were carried out. The neutron spectrum at 500cm from the PE moderator was simulated by MCNP and PHITS software. The counts of 0.01eV to 1.0eV neutrons were simulated by MCNP and detected by the thermal neutron detector in the experiment. These data were compared and analyzed. Then this method is researched on designing the complex structure of PE and the composite material consisting of PE, lead and zirconium dioxide.

NEUTRONIC REACTOR

DOEpatents

Wigner, E.P.

1958-04-22

A nuclear reactor for isotope production is described. This reactor is designed to provide a maximum thermal neutron flux in a region adjacent to the periphery of the reactor rather than in the center of the reactor. The core of the reactor is generally centrally located with respect tn a surrounding first reflector, constructed of beryllium. The beryllium reflector is surrounded by a second reflector, constructed of graphite, which, in tune, is surrounded by a conventional thermal shield. Water is circulated through the core and the reflector and functions both as a moderator and a coolant. In order to produce a greatsr maximum thermal neutron flux adjacent to the periphery of the reactor rather than in the core, the reactor is designed so tbat the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the materials in the reflector is approximately twice the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the material of the core of the reactor.

Development of a Short-Lived Radioisotope Production Service (SRPS) for CTTC at the University of Alberta SLOWPOKE Reactor Facility

DTIC Science & Technology

2004-12-01

abundance and neutron cross-section of 17~r (the precursor of 171 Er~~limit,tb~’Xi!Y o~_ 171Er that could be produced and delivered to Suf field to about...the radioisotope being produced. Additional factors relate to the irradiation conditions and include the reactor neutron flux and the irradiation...generally be desirable to have single radioisotopic sources with nuclear characteristics (e.g., half-life, gamma-ray energies and emission rates

Nuclear reactor neutron shielding

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

Speaker, Daniel P; Neeley, Gary W; Inman, James B

A nuclear reactor includes a reactor pressure vessel and a nuclear reactor core comprising fissile material disposed in a lower portion of the reactor pressure vessel. The lower portion of the reactor pressure vessel is disposed in a reactor cavity. An annular neutron stop is located at an elevation above the uppermost elevation of the nuclear reactor core. The annular neutron stop comprises neutron absorbing material filling an annular gap between the reactor pressure vessel and the wall of the reactor cavity. The annular neutron stop may comprise an outer neutron stop ring attached to the wall of the reactormore » cavity, and an inner neutron stop ring attached to the reactor pressure vessel. An excore instrument guide tube penetrates through the annular neutron stop, and a neutron plug comprising neutron absorbing material is disposed in the tube at the penetration through the neutron stop.« less

Neutron guide

DOEpatents

Greene, Geoffrey L.

1999-01-01

A neutron guide in which lengths of cylindrical glass tubing have rectangular glass plates properly dimensioned to allow insertion into the cylindrical glass tubing so that a sealed geometrically precise polygonal cross-section is formed in the cylindrical glass tubing. The neutron guide provides easier alignment between adjacent sections than do the neutron guides of the prior art.

Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE

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

Jandel, M.; Bredeweg, T. A.; Fowler, M. M.

2009-01-28

Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for {sup 241}Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for {sup 243}Am for neutron energies between 10 eV and 250 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on {sup 242m}Am will be presented where the fission events were actively triggered during the experiments. In these experiments, a Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in themore » center of the DANCE array was used as a fission-tagging detector to separate (n,{gamma}) events from (n,f) events. The first direct observation of neutron capture on {sup 242m}Am in the resonance region in between 2 and 9 eV of the neutron energy was obtained.« less

Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE

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

Jandel, Marian

2008-01-01

Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for {sup 241}Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for {sup 243}Am for neutron energies between 35 eV and 200 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on {sup 242m}Am will be presented, where the fission events were actively triggered during the experiments. In these experiments, the Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in themore » center of the DANCE array was used as a fission-tagging detector to separate (n,{gamma}) from (n,f) events. The first evidence of neutron capture on {sup 242m}Am in the resonance region in between 2 and 9 eV of the neutron energy was obtained.« less

Asymmetry Studies in the Production of $$\\Lambda^0/\\bar \\Lambda^0$$, $$\\Xi^-/\\bar{\\Xi}^+$$ and $$\\Omega^-/\\bar{\\Omega}^+$$ Hyperons in 500 GeV/c $$\\pi^-$$ - Nucleon Interactions (in Portuguese)

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

Solano Salinas, Carlos Javier

Using data from fprmilab fixed-target experiment E791, we have measmed for the first time particle/antiparticle production asymmetries formore » $$\\Lambda^0 \\Xi^-$$ and $$\\Omega^-$$ hyperons in $$\\pi^-$$nucleon interactions at 500 GeV /c as joint functions of $$x_F$$ and $$p^2_{\\tau}$$ over the ranges $$-0.12 \\le x_F \\le 0.12$$ and $$0 \\le p^2_{\\tau} \\le 4 (GeV/c)^2$$. There is now direct evidence of a basic asymmetry, even at $$x_F$$ = 0.0, which may be due to associated production. In addition, there are leading-particle-type effects which are qualitativrly like what one would expect from rrcmnbination models or their alternatives. WP used the Dnal Parton Model (DPM) to cakulate the asymmetry for the $$\\Lambda^0$$ and compared with the Lund model (PYTHIA /JETSET) predictions and with om experimental results.« less

77 FR 29633 - Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC, Alta Wind XII, LLC...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-18

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL12-68-000] Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC, Alta Wind XII, LLC, Alta Wind XIII, LLC, Alta Wind XIV, LLC, Alta Wind XV, LLC, Alta Windpower Development, LLC, TGP Development Company, LLC...

Lung Cancer Workshop XI: Tobacco-Induced Disease: Advances in Policy, Early Detection and Management.

PubMed

Mulshine, James L; Avila, Rick; Yankelevitz, David; Baer, Thomas M; Estépar, Raul San Jose; Ambrose, Laurie Fenton; Aldigé, Carolyn R

2015-05-01

The Prevent Cancer Foundation Lung Cancer Workshop XI: Tobacco-Induced Disease: Advances in Policy, Early Detection and Management was held in New York, NY on May 16 and 17, 2014. The two goals of the Workshop were to define strategies to drive innovation in precompetitive quantitative research on the use of imaging to assess new therapies for management of early lung cancer and to discuss a process to implement a national program to provide high quality computed tomography imaging for lung cancer and other tobacco-induced disease. With the central importance of computed tomography imaging for both early detection and volumetric lung cancer assessment, strategic issues around the development of imaging and ensuring its quality are critical to ensure continued progress against this most lethal cancer.

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.

NEUTRON DENSITY CONTROL IN A NEUTRONIC REACTOR

DOEpatents

Young, G.J.

1959-06-30

The method and means for controlling the neutron density in a nuclear reactor is described. It describes the method and means for flattening the neutron density distribution curve across the reactor by spacing the absorbing control members to varying depths in the central region closer to the center than to the periphery of the active portion of the reactor to provide a smaller neutron reproduction ratio in the region wherein the members are inserted, than in the remainder of the reactor thereby increasing the over-all potential power output.

Clifford G. Shull, Neutron Diffraction, Hydrogen Atoms, and Neutron

Science.gov Websites

Analysis of NaH and NaD, DOE Technical Report, April 1947 The Diffraction of Neutrons by Crystalline Powders; DOE Technical Report; 1948 Neutron Diffraction Studies, DOE Technical Report, 1948 Laue Structure of Thorium and Zirconium Dihydrides by X-ray and Neutron Diffraction, DOE Technical Report, April

Semiconductor neutron detector

DOEpatents

Ianakiev, Kiril D [Los Alamos, NM; Littlewood, Peter B [Cambridge, GB; Blagoev, Krastan B [Arlington, VA; Swinhoe, Martyn T [Los Alamos, NM; Smith, James L [Los Alamos, NM; Sullivan, Clair J [Los Alamos, NM; Alexandrov, Boian S [Los Alamos, NM; Lashley, Jason Charles [Santa Fe, NM

2011-03-08

A neutron detector has a compound of lithium in a single crystal form as a neutron sensor element. The lithium compound, containing improved charge transport properties, is either lithium niobate or lithium tantalate. The sensor element is in direct contact with a monitor that detects an electric current. A signal proportional to the electric current is produced and is calibrated to indicate the neutrons sensed. The neutron detector is particularly useful for detecting neutrons in a radiation environment. Such radiation environment may, e.g. include gamma radiation and noise.

Intense fusion neutron sources

NASA Astrophysics Data System (ADS)

Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

2010-04-01

The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 1015-1021 neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 1020 neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the neutron itself.

A Neutron Diffractometer for a Long Pulsed Neutron Source

NASA Astrophysics Data System (ADS)

Sokol, Paul; Wang, Cailin

Long pulsed neutron sources are being actively developed as small university based sources and are being considered for the next generation of high powered sources, such as the European Neutron Source (ESS) and the Spallation Neutron Source (SNS) second target station. New instrumentation concepts will be required to effectively utilize the full spectrum of neutrons generated by these sources. Neutron diffractometers, which utilize time-of-flight (TOF) techniques for wavelength resolution, are particularly problematic. We describe an instrument for a long pulsed source that provides resolution comparable to that obtained on short pulsed sources without the need of long incident flight paths. We accomplish this by utilizing high speed choppers to impose a time structure on the spectrum of incident neutrons. By strategically positioning these choppers the response matrix assumes a convenient form that can be deconvoluted from the measured TOF spectrum to produce the diffraction pattern of the sample. We compare the performance of this instrument to other possible diffraction instruments that could be utilized on a long pulsed source.

Neutron dose equivalent meter

DOEpatents

Olsher, Richard H.; Hsu, Hsiao-Hua; Casson, William H.; Vasilik, Dennis G.; Kleck, Jeffrey H.; Beverding, Anthony

1996-01-01

A neutron dose equivalent detector for measuring neutron dose capable of accurately responding to neutron energies according to published fluence to dose curves. The neutron dose equivalent meter has an inner sphere of polyethylene, with a middle shell overlying the inner sphere, the middle shell comprising RTV.RTM. silicone (organosiloxane) loaded with boron. An outer shell overlies the middle shell and comprises polyethylene loaded with tungsten. The neutron dose equivalent meter defines a channel through the outer shell, the middle shell, and the inner sphere for accepting a neutron counter tube. The outer shell is loaded with tungsten to provide neutron generation, increasing the neutron dose equivalent meter's response sensitivity above 8 MeV.

Correlated Observations of Epithermal Neutrons and Polar Illumination for Orbital Neutron Detectors

NASA Technical Reports Server (NTRS)

McClanahan, T. P.; Mitrofanov, I. G.; Boynton, W. V.; Chin, G.; Droege, G.; Evans, L. G.; Garvin, J.; Harshman, K.; Malakhov, A.; Livengood, T.;

Upbend and M1 scissors mode in neutron-rich nuclei - consequences for r-process $$(n,\\gamma )$$ reaction rates

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

Larsen, A. C.; Goriely, S.; Bernstein, L. A.

2015-01-01

An enhanced probability for low-energy γ-emission ( upbend, Eγ < 3 MeV) at high excitation energies has been observed for several light and medium-mass nuclei close to the valley of stability. Also the M1 scissors mode seen in deformed nuclei increases the γ-decay probability for low-energy γ-rays (E γ ≈ 2–3 MeV). These phenomena, if present in neutron-rich nuclei, have the potential to increase radiative neutron-capture rates relevant for the r-process. Furthermore, the experimental and theoretical status of the upbend is discussed, and preliminary calculations of (n,γ) reaction rates for neutron-rich, mid-mass nuclei including the scissors mode are shown.

Compact neutron generator

DOEpatents

Leung, Ka-Ngo; Lou, Tak Pui

2005-03-22

A compact neutron generator has at its outer circumference a toroidal shaped plasma chamber in which a tritium (or other) plasma is generated. A RF antenna is wrapped around the plasma chamber. A plurality of tritium ion beamlets are extracted through spaced extraction apertures of a plasma electrode on the inner surface of the toroidal plasma chamber and directed inwardly toward the center of neutron generator. The beamlets pass through spaced acceleration and focusing electrodes to a neutron generating target at the center of neutron generator. The target is typically made of titanium tubing. Water is flowed through the tubing for cooling. The beam can be pulsed rapidly to achieve ultrashort neutron bursts. The target may be moved rapidly up and down so that the average power deposited on the surface of the target may be kept at a reasonable level. The neutron generator can produce fast neutrons from a T-T reaction which can be used for luggage and cargo interrogation applications. A luggage or cargo inspection system has a pulsed T-T neutron generator or source at the center, surrounded by associated gamma detectors and other components for identifying explosives or other contraband.

A neutron activation spectrometer and neutronic experimental platform for the National Ignition Facility (invited)

NASA Astrophysics Data System (ADS)

Yeamans, C. B.; Gharibyan, N.

2016-11-01

At the National Ignition Facility, the diagnostic instrument manipulator-based neutron activation spectrometer is used as a diagnostic of implosion performance for inertial confinement fusion experiments. Additionally, it serves as a platform for independent neutronic experiments and may be connected to fast recording systems for neutron effect tests on active electronics. As an implosion diagnostic, the neutron activation spectrometers are used to quantify fluence of primary DT neutrons, downscattered neutrons, and neutrons above the primary DT neutron energy created by reactions of upscattered D and T in flight. At a primary neutron yield of 1015 and a downscattered fraction of neutrons in the 10-12 MeV energy range of 0.04, the downscattered neutron fraction can be measured to a relative uncertainty of 8%. Significant asymmetries in downscattered neutrons have been observed. Spectrometers have been designed and fielded to measure the tritium-tritium and deuterium-tritium neutron outputs simultaneously in experiments using DT/TT fusion ratio as a direct measure of mix of ablator into the gas.

A neutron activation spectrometer and neutronic experimental platform for the National Ignition Facility (invited).

PubMed

Yeamans, C B; Gharibyan, N

2016-11-01

At the National Ignition Facility, the diagnostic instrument manipulator-based neutron activation spectrometer is used as a diagnostic of implosion performance for inertial confinement fusion experiments. Additionally, it serves as a platform for independent neutronic experiments and may be connected to fast recording systems for neutron effect tests on active electronics. As an implosion diagnostic, the neutron activation spectrometers are used to quantify fluence of primary DT neutrons, downscattered neutrons, and neutrons above the primary DT neutron energy created by reactions of upscattered D and T in flight. At a primary neutron yield of 10 15 and a downscattered fraction of neutrons in the 10-12 MeV energy range of 0.04, the downscattered neutron fraction can be measured to a relative uncertainty of 8%. Significant asymmetries in downscattered neutrons have been observed. Spectrometers have been designed and fielded to measure the tritium-tritium and deuterium-tritium neutron outputs simultaneously in experiments using DT/TT fusion ratio as a direct measure of mix of ablator into the gas.

Neutron tubes

DOEpatents

Leung, Ka-Ngo [Hercules, CA; Lou, Tak Pui [Berkeley, CA; Reijonen, Jani [Oakland, CA

2008-03-11

A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

Reflection Asymmetric Shapes in the Neutron-Rich 140,143Ba Isotopes

NASA Astrophysics Data System (ADS)

Zhu Sheng-jiang (S, J. Zhu; Wang, Mu-ge; J, H. Hamilton; A, V. Ramayya; B, R. S. Babu; W, C. Ma; Long, Gui-lu; Deng, Jing-kang; Zhu, Ling-yan; Li, Ming; T, N. Ginter; J, Komicki; J, D. Cole; R, Aryaeinejad; Y, K. Dardenne; M, W. Drigert; J, O. Rasmussen; Ts, Yu Oganessian; M, A. Stoyer; S, Y. Chu; K, E. Gregorich; M, F. Mohar; S, G. Prussin; I, Y. Lee; N, R. Johnson; F, K. McGowan

1997-08-01

Level schemes for the neutron-rich 140,143Ba nuclei have been determined by study of prompt γ-rays in spontaneous fission of 252Cf. The level pattern and enhanced E1 transitions between π = + and π = - bands show reflection asymmetric shapes with simplex quantum number s = +1 in 140Ba and s = ±i in 143Ba, respectively. The octupole deformation stability with spin variation has been discussed.

Neutron scatter camera

DOEpatents

Mascarenhas, Nicholas; Marleau, Peter; Brennan, James S.; Krenz, Kevin D.

2010-06-22

An instrument that will directly image the fast fission neutrons from a special nuclear material source has been described. This instrument can improve the signal to background compared to non imaging neutron detection techniques by a factor given by ratio of the angular resolution window to 4.pi.. In addition to being a neutron imager, this instrument will also be an excellent neutron spectrometer, and will be able to differentiate between different types of neutron sources (e.g. fission, alpha-n, cosmic ray, and D-D or D-T fusion). Moreover, the instrument is able to pinpoint the source location.

Disclosure of the oscillations in kinetics of the reactor pressure vessel steel damage at fast neutron intensity decreasing

NASA Astrophysics Data System (ADS)

Krasikov, E.; Nikolaenko, V.

2017-01-01

Fast neutron intensity influence on reactor materials radiation damage is a critically important question in the problem of the correct use of the accelerated irradiation tests data for substantiation of the materials workability in real irradiation conditions that is low neutron intensity. Investigations of the fast neutron intensity (flux) influence on radiation damage and experimental data scattering reveal the existence of non-monotonous sections in kinetics of the reactor pressure vessels (RPV) steel damage. Discovery of the oscillations as indicator of the self-organization processes presence give reasons for new ways searching on reactor pressure vessel (RPV) steel radiation stability increasing and attempt of the self-restoring metal elaboration. Revealing of the wavelike process in the form of non monotonous parts of the kinetics of radiation embrittlement testifies that periodic transformation of the structure take place. This fact actualizes the problem of more precise definition of the RPV materials radiation embrittlement mechanisms and gives reasons for search of the ways to manage the radiation stability (nanostructuring and so on to stimulate the radiation defects annihilation), development of the means for creating of more stableness self recovering smart materials.

Small-Angle Neutron Scattering and Neutron Spin Echo Characterization of Monoclonal Antibody Self-Associations at High Concentrations

NASA Astrophysics Data System (ADS)

Yearley, Eric; Zarraga, Isidro (Dan); Godfrin, Paul (Doug); Perevozchikova, Tatiana; Wagner, Norman; Liu, Yun

2013-03-01

Concentrated therapeutic protein formulations offer numerous delivery and stability challenges. In particular, it has been found that several therapeutic proteins exhibit a large increase in viscosity as a function of concentration that may be dependent on the protein-protein interactions. Small-Angle Neutron Scattering (SANS) and Neutron Spin Echo (NSE) investigations have been performed to probe the protein-protein interactions and diffusive properties of highly concentrated MAbs. The SANS data demonstrate that the inter-particle interactions for a highly viscous MAb at high concentrations (MAb1) are highly attractive, anisotropic and change significantly with concentration while the viscosity and interactions do not differ considerably for MAb2. The NSE results furthermore indicate that MAb1 and MAb2 have strong concentration dependencies of dynamics at high Q that are correlated to the translational motion of the proteins. Finally, it has also been revealed that the individual MAb1 proteins form small clusters at high concentrations in contrast to the MAb2 proteins, which are well-dispersed. It is proposed that the formation of these clusters is the primary cause of the dramatic increase in viscosity of MAb1 in crowded or concentrated environments.

Novel mutation of FKBP10 in a pediatric patient with osteogenesis imperfecta type XI identified by clinical exome sequencing

PubMed Central

Velasco, Harvy Mauricio; Morales, Jessica L

2017-01-01

Osteogenesis imperfecta (OI) is a hereditary disease characterized by bone fragility caused by mutations in the proteins that support the formation of the extracellular matrix in the bone. The diagnosis of OI begins with clinical suspicion, from phenotypic findings at birth, low-impact fractures during childhood or family history that may lead to it. However, the variability in the semiology of the disease does not allow establishing an early diagnosis in all cases, and unfortunately, specific clinical data provided by the literature only report 28 patients with OI type XI. This information is limited and heterogeneous, and therefore, detailed information on the natural history of this disease is not yet available. This paper reports the case of a male patient who, despite undergoing multidisciplinary management, did not have a diagnosis for a long period of time, and could only be given one with the use of whole-exome sequencing. The use of the next-generation sequencing in patients with ultrarare genetic diseases, including skeletal dysplasias, should be justified when clear clinical criteria and an improvement in the quality of life of the patients and their families are intended while reducing economic and time costs. Thus, this case report corresponds to the 29th patient affected with OI type XI, and the 18th mutation in FKBP10, causative of this pathology. PMID:29158687

High-pressure cell for neutron reflectometry of supercritical and subcritical fluids at solid interfaces

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

Carmichael, Justin R; Rother, Gernot; Browning, Jim

2012-01-01

A new high-pressure cell design for use in neutron reflectometry (NR) for pressures up to 50 MPa and a temperature range of 300 473 K is described. The cell design guides the neutron beam through the working crystal without passing through additional windows or the bulk fluid, which provides for a high neutron transmission, low scattering background, and low beam distortion. The o-ring seal is suitable for a wide range of subcritical and supercritical fluids and ensures high chemical and pressure stability. Wafers with a diameter of 5.08 cm (2 in.) and 5 mm or 10 mm thickness can bemore » used with the cells, depending on the required pressure and momentum transfer range. The fluid volume in the sample cell is very small at about 0.1 ml, which minimizes scattering background and stored energy. The cell design and pressure setup for measurements with supercritical fluids are described. NR data are shown for silicon/silicon oxide and quartz wafers measured against air and subsequently within the high-pressure cell to demonstrate the neutron characteristics of the high-pressure cell. Neutron reflectivity data for supercritical CO2 in contact with quartz and Si/SiO2 wafers are also shown.« less

Reintroducing electrostatics into macromolecular crystallographic refinement: application to neutron crystallography and DNA hydration.

PubMed

Fenn, Timothy D; Schnieders, Michael J; Mustyakimov, Marat; Wu, Chuanjie; Langan, Paul; Pande, Vijay S; Brunger, Axel T

2011-04-13

Most current crystallographic structure refinements augment the diffraction data with a priori information consisting of bond, angle, dihedral, planarity restraints, and atomic repulsion based on the Pauli exclusion principle. Yet, electrostatics and van der Waals attraction are physical forces that provide additional a priori information. Here, we assess the inclusion of electrostatics for the force field used for all-atom (including hydrogen) joint neutron/X-ray refinement. Two DNA and a protein crystal structure were refined against joint neutron/X-ray diffraction data sets using force fields without electrostatics or with electrostatics. Hydrogen-bond orientation/geometry favors the inclusion of electrostatics. Refinement of Z-DNA with electrostatics leads to a hypothesis for the entropic stabilization of Z-DNA that may partly explain the thermodynamics of converting the B form of DNA to its Z form. Thus, inclusion of electrostatics assists joint neutron/X-ray refinements, especially for placing and orienting hydrogen atoms. Copyright © 2011 Elsevier Ltd. All rights reserved.

Reintroducing Electrostatics into Macromolecular Crystallographic Refinement: Application to Neutron Crystallography and DNA Hydration

PubMed Central

Fenn, Timothy D.; Schnieders, Michael J.; Mustyakimov, Marat; Wu, Chuanjie; Langan, Paul; Pande, Vijay S.; Brunger, Axel T.

2011-01-01

Summary Most current crystallographic structure refinements augment the diffraction data with a priori information consisting of bond, angle, dihedral, planarity restraints and atomic repulsion based on the Pauli exclusion principle. Yet, electrostatics and van der Waals attraction are physical forces that provide additional a priori information. Here we assess the inclusion of electrostatics for the force field used for all-atom (including hydrogen) joint neutron/X-ray refinement. Two DNA and a protein crystal structure were refined against joint neutron/X-ray diffraction data sets using force fields without electrostatics or with electrostatics. Hydrogen bond orientation/geometry favors the inclusion of electrostatics. Refinement of Z-DNA with electrostatics leads to a hypothesis for the entropic stabilization of Z-DNA that may partly explain the thermodynamics of converting the B form of DNA to its Z form. Thus, inclusion of electrostatics assists joint neutron/X-ray refinements, especially for placing and orienting hydrogen atoms. PMID:21481775

Boron neutron capture therapy induces apoptosis of glioma cells through Bcl-2/Bax

PubMed Central

2010-01-01

Background Boron neutron capture therapy (BNCT) is an alternative treatment modality for patients with glioma. The aim of this study was to determine whether induction of apoptosis contributes to the main therapeutic efficacy of BNCT and to compare the relative biological effect (RBE) of BNCT, γ-ray and reactor neutron irradiation. Methods The neutron beam was obtained from the Xi'an Pulsed Reactor (XAPR) and γ-rays were obtained from [60Co] γ source of the Fourth Military Medical University (FMMU) in China. Human glioma cells (the U87, U251, and SHG44 cell lines) were irradiated by neutron beams at the XAPR or [60Co] γ-rays at the FMMU with different protocols: Group A included control nonirradiated cells; Group B included cells treated with 4 Gy of [60Co] γ-rays; Group C included cells treated with 8 Gy of [60Co] γ-rays; Group D included cells treated with 4 Gy BPA (p-borono-phenylalanine)-BNCT; Group E included cells treated with 8 Gy BPA-BNCT; Group F included cells irradiated in the reactor for the same treatment period as used for Group D; Group G included cells irradiated in the reactor for the same treatment period as used for Group E; Group H included cells irradiated with 4 Gy in the reactor; and Group I included cells irradiated with 8 Gy in the reactor. Cell survival was determined using the 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium (MTT) cytotoxicity assay. The morphology of cells was detected by Hoechst33342 staining and transmission electron microscope (TEM). The apoptosis rate was detected by flow cytometer (FCM). The level of Bcl-2 and Bax protein was measured by western blot analysis. Results Proliferation of U87, U251, and SHG44 cells was much more strongly inhibited by BPA-BNCT than by irradiation with [60Co] γ-rays (P < 0.01). Nuclear condensation was determined using both a fluorescence technique and electron microscopy in all cell lines treated with BPA-BNCT. Furthermore, the cellular apoptotic rates in Group D and Group E

Assessment of compatibility among Armillaria cepistipes, A. sinapina, and North American biological species X and XI, using culture morphology and molecular biology

Treesearch

Mark T. Banik; Harold H. Burdsall

1998-01-01

Ten single-spore isolates each of Armillaria sinapina, A. cepistipes, and North American biological species (NABS)X and XI were paired in all combinations. A second set of ten single-spore isolates of each species was likewise paired. Each pairing was duplicated for a total of 3280 pairs. Using the standard morphological criteria (e.g., fluffy, crustose) to assess the...

Neutron reflecting supermirror structure

DOEpatents

Wood, James L.

1992-01-01

An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. One layer of each set of bilayers consist of titanium, and the second layer of each set of bilayers consist of an alloy of nickel with carbon interstitially present in the nickel alloy.

Novel Scintillating Materials Based on Phenyl-Polysiloxane for Neutron Detection and Monitoring

NASA Astrophysics Data System (ADS)

Degerlier, M.; Carturan, S.; Gramegna, F.; Marchi, T.; Palma, M. Dalla; Cinausero, M.; Maggioni, G.; Quaranta, A.; Collazuol, G.; Bermudez, J.

Neutron detectors are extensively used at many nuclear research facilities across Europe. Their application range covers many topics in basic and applied nuclear research: in nuclear structure and reaction dynamics (reaction reconstruction and decay studies); in nuclear astrophysics (neutron emission probabilities); in nuclear technology (nuclear data measurements and in-core/off-core monitors); in nuclear medicine (radiation monitors, dosimeters); in materials science (neutron imaging techniques); in homeland security applications (fissile materials investigation and cargo inspection). Liquid scintillators, widely used at present, have however some drawbacks given by toxicity, flammability, volatility and sensitivity to oxygen that limit their duration and quality. Even plastic scintillators are not satisfactory because they have low radiation hardness and low thermal stability. Moreover organic solvents may affect their optical properties due to crazing. In order to overcome these problems, phenyl-polysiloxane based scintillators have been recently developed at Legnaro National Laboratory. This new solution showed very good chemical and thermal stability and high radiation hardness. The results on the different samples performance will be presented, paying special attention to a characterization comparison between synthesized phenyl containing polysiloxane resins where a Pt catalyst has been used and a scintillating material obtained by condensation reaction, where tin based compounds are used as catalysts. Different structural arrangements as a result of different substituents on the main chain have been investigated by High Resolution X-Ray Diffraction, while the effect of improved optical transmittance on the scintillation yield has been elucidated by a combination of excitation/fluorescence measurements and scintillation yield under exposure to alpha and γ-rays.

Broken SU(3) antidecuplet for {Theta}{sup +} and {Xi}{sub 3/2}

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

Pakvasa, Sandip; Suzuki, Mahiko

2004-05-05

If the narrow exotic baryon resonances {Theta}{sup +}(1540) and {Xi}{sub 3/2} are members of the J{sup P} = 1/2{sup +} antidecuplet with N*(1710), the octet-antidecuplet mixing is required not only by the mass spectrum but also by the decay pattern of N*(1710). This casts doubt on validity of the {Theta}{sup +} mass prediction by the chiral soliton model. While all pieces of the existing experimental information point to a small octet-decuplet mixing, the magnitude of mixing required by the mass spectrum is not consistent with the value needed to account for the hadronic decay rates. The discrepancy is not resolvedmore » even after the large experimental uncertainty is taken into consideration. We fail to find an alternative SU(3) assignment even with different spin-parity assignment. When we extend the analysis to mixing with a higher SU(3) multiplet, we find one experimentally testable scenario in the case of mixing with a 27-plet.« less

A probe for neutron activation analysis in a drill hole using 252Cf, and a Ge(Li) detector cooled by a melting cryogen

USGS Publications Warehouse

Tanner, A.B.; Moxham, R.M.; Senftle, F.E.; Baicker, J.A.

1972-01-01

A sonde has been built for high-resolution measurement of natural or neutron-induced gamma rays in boreholes. The sonde is 7.3 cm in diameter and about 2.2 m in length and weighs about 16 kg. The lithium-compensated germanium semiconductor detector is stabilized at -185 to -188??C for as much as ten hours by a cryostatic reservoir containing melting propane. During periods when the sonde is not in use the propane is kept frozen by a gravity-fed trickle of liquid nitrogen from a reservoir temporarily attached to the cryostat section. A 252Cf source, shielded from the detector, may be placed in the bottom section of the sonde for anlysis by measurement of neutron-activation or neutron-capture gamma rays. Stability of the cryostat with changing hydrostatic pressure, absence of vibration, lack of need for power to the cryostat during operation, and freedom of orientation make the method desirable for borehole, undersea, space, and some laboratory applications. ?? 1972.

Medusae Fossae-Elysium Region, Mars: Depression in the HEND/Odyssey Map of Mars Epithermal Neutrons

NASA Technical Reports Server (NTRS)

Ivanov, M. A.; Litvak, M. L.; Mitrofanov, I. G.; Boynton, W.; Saunders, R. S.

2003-01-01

The first data from the Gamma Ray Spectrometer (GRS) onboard Mars Odyssey spacecraft showed that the low neutron fluxes characterize both subpolar regions of Mars. The low neutron fluxes mean the presence of hydrogen-rich soils and have been interpreted as an indication on abundant water ice in these areas. The equatorial region of Mars (equatorward of approx. 50 deg) is characterized by higher fluxes of both epithermal (0.4 eV-100 keV, come from depth 1-2 m) and fast (3.4-7.3 MeV, come from depth 0.2-0.3 m) neutrons meaning that this area is mostly dry. The pattern of distribution of the neutron fluxes is in a good agreement with the theoretical predictions on the stability of ground ice on present Mars. The actual distribution of the ice, however, depends on variations of thermal inertia of soils and albedo of the surface. The flux of the epithermal neutrons detected by the HEND instrument, which is part of GRS, has two noticeable depressions in the equatorial region, one in Arabia Terra and another in the Medusae Fossae-Elysium region (MFER). Here we present the initial results of analysis of characteristics of the neutron fluxes and regional geological setting of the epithermal neutron depression in this area. The main goal of our study was to put some constraints on the time of the anomaly formation and to assess possible form of hydrogen (ground ice vs. chemically bound water) there.

PREFACE: XI Latin American Workshop on Nonlinear Phenomena

NASA Astrophysics Data System (ADS)

Anteneodo, Celia; da Luz, Marcos G. E.

2010-09-01

The XI Latin American Workshop on Nonlinear Phenomena (LAWNP) has been held in Búzios-RJ, Brazil, from 5-9 October 2009. This international conference is one in a series that have gathered biennially, over the past 21 years, physicists and other scientists who direct their work towards several aspects of nonlinear phenomena and complex systems. The main purpose of LAWNP meetings is to create a friendly and motivating environment, such that researchers from Latin America and from other parts of the globe can discuss not only their own latest results but also the trends and perspectives in this very interdisciplinary field of investigation. Hence, it constitutes a forum for promoting scientific collaboration and fomenting the emergence of new ideas, helping to advance the field. The XI edition (LAWNP'09) has gathered more than 230 scientists and students (most from Latin America), covering all of the world (27 different countries from North and South America, Asia, Europe, and Oceania). In total there were 18 plenary lectures, 80 parallel talks, and 140 poster contributions. A stimulating round-table discussion also took place devoted to the present and future of the Latin American Institutions in Complex Phenomena (a summary can be found at http://lawnp09.fis.puc-rio.br, in the Round-Table report link). The 2009 workshop was devoted to a wide scope of themes and points of view, pursuing to include the latest trends and developments in the science of nonlinearity. In this way, we have a great pleasure in publishing this Proceedings volume based on the high quality scientific works presented at LAWNP'09, covering already established methods as well as new approaches, discussing both theoretical and practical aspects, and addressing paradigmatic systems and also completely new problems, in nonlinearity and complexity. In fact, the present volume may be a very valuable reference for those interested in an overview on how nonlinear interactions can affect different

Time-resolved neutron imaging at ANTARES cold neutron beamline

NASA Astrophysics Data System (ADS)

Tremsin, A. S.; Dangendorf, V.; Tittelmeier, K.; Schillinger, B.; Schulz, M.; Lerche, M.; Feller, W. B.

2015-07-01

In non-destructive evaluation with X-rays light elements embedded in dense, heavy (or high-Z) matrices show little contrast and their structural details can hardly be revealed. Neutron radiography, on the other hand, provides a solution for those cases, in particular for hydrogenous materials, owing to the large neutron scattering cross section of hydrogen and uncorrelated dependency of neutron cross section on the atomic number. The majority of neutron imaging experiments at the present time is conducted with static objects mainly due to the limited flux intensity of neutron beamline facilities and sometimes due to the limitations of the detectors. However, some applications require the studies of dynamic phenomena and can now be conducted at several high intensity beamlines such as the recently rebuilt ANTARES beam line at the FRM-II reactor. In this paper we demonstrate the capabilities of time resolved imaging for repetitive processes, where different phases of the process can be imaged simultaneously and integrated over multiple cycles. A fast MCP/Timepix neutron counting detector was used to image the water distribution within a model steam engine operating at 10 Hz frequency. Within <10 minutes integration the amount of water was measured as a function of cycle time with a sub-mm spatial resolution, thereby demonstrating the capabilities of time-resolved neutron radiography for the future applications. The neutron spectrum of the ANTARES beamline as well as transmission spectra of a Fe sample were also measured with the Time Of Flight (TOF) technique in combination with a high resolution beam chopper. The energy resolution of our setup was found to be ~ 0.8% at 5 meV and ~ 1.7% at 25 meV. The background level (most likely gammas and epithermal/fast neutrons) of the ANTARES beamline was also measured in our experiments and found to be on the scale of 3% when no filters are installed in the beam. Online supplementary data available from stacks.iop.org/jinst/10

PERSONNEL NEUTRON DOSIMETER

DOEpatents

Fitzgerald, J.J.; Detwiler, C.G. Jr.

1960-05-24

A description is given of a personnel neutron dosimeter capable of indicating the complete spectrum of the neutron dose received as well as the dose for each neutron energy range therein. The device consists of three sets of indium foils supported in an aluminum case. The first set consists of three foils of indium, the second set consists of a similar set of indium foils sandwiched between layers of cadmium, whereas the third set is similar to the second set but is sandwiched between layers of polyethylene. By analysis of all the foils the neutron spectrum and the total dose from neutrons of all energy levels can be ascertained.

NEUTRONIC REACTOR

DOEpatents

Wade, E.J.

1958-09-16

This patent relates to a reflector means for a neutronic reactor. A reflector comprised of a plurality of vertically movable beryllium control members is provided surrounding the sides of the reactor core. An absorber of fast neutrons comprised of natural uramum surrounds the reflector. An absorber of slow neutrons surrounds the absorber of fast neutrons and is formed of a plurality of beryllium blocks having natural uranium members distributcd therethrough. in addition, a movable body is positioned directly below the core and is comprised of a beryllium reflector and an absorbing member attached to the botiom thereof, the absorbing member containing a substance selected from the goup consisting of natural urantum and Th/sup 232/.

New precision measurements of free neutron beta decay with cold neutrons

DOE PAGES

Baeßler, Stefan; Bowman, James David; Penttilä, Seppo I.; ...

2014-10-14

Precision measurements in free neutron beta decay serve to determine the coupling constants of beta decay, and offer several stringent tests of the standard model. This study describes the free neutron beta decay program planned for the Fundamental Physics Beamline at the Spallation Neutron Source at Oak Ridge National Laboratory, and finally puts it into the context of other recent and planned measurements of neutron beta decay observables.

Organic metal neutron detector

DOEpatents

Butler, M.A.; Ginley, D.S.

1984-11-21

A device for detection of neutrons comprises: as an active neutron sensing element, a conductive organic polymer having an electrical conductivity and a cross-section for said neutrons whereby a detectable change in said conductivity is caused by impingement of said neutrons on the conductive organic polymer which is responsive to a property of said polymer which is altered by impingement of said neutrons on the polymer; and means for associating a change in said alterable property with the presence of neutrons at the location of said device.

Layered semiconductor neutron detectors

DOEpatents

Mao, Samuel S; Perry, Dale L

2013-12-10

Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

Spectral correction factors for conventional neutron dosemeters used in high-energy neutron environments.

PubMed

Lee, K W; Sheu, R J

2015-04-01

High-energy neutrons (>10 MeV) contribute substantially to the dose fraction but result in only a small or negligible response in most conventional moderated-type neutron detectors. Neutron dosemeters used for radiation protection purpose are commonly calibrated with (252)Cf neutron sources and are used in various workplace. A workplace-specific correction factor is suggested. In this study, the effect of the neutron spectrum on the accuracy of dose measurements was investigated. A set of neutron spectra representing various neutron environments was selected to study the dose responses of a series of Bonner spheres, including standard and extended-range spheres. By comparing (252)Cf-calibrated dose responses with reference values based on fluence-to-dose conversion coefficients, this paper presents recommendations for neutron field characterisation and appropriate correction factors for responses of conventional neutron dosemeters used in environments with high-energy neutrons. The correction depends on the estimated percentage of high-energy neutrons in the spectrum or the ratio between the measured responses of two Bonner spheres (the 4P6_8 extended-range sphere versus the 6″ standard sphere). © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Neutron beam characterization measurements at the Manuel Lujan Jr. neutron scattering center

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

Mocko, Michal; Muhrer, Guenter; Daemen, Luke L

We have measured the neutron beam characteristics of neutron moderators at the Manuel Lujan Jr. Neutron Scattering Center at LANSCE. The absolute thermal neutron flux, energy spectra and time emission spectra were measured for the high resolution and high intensity decoupled water, partially coupled liquid hydrogen and partially coupled water moderators. The results of our experimental study will provide an insight into aging of different target-moderator-reflector-shield components as well as new experimental data for benchmarking of neutron transport codes.

Synthesis, structural and optical characterization of APbX{sub 3} (A=methylammonium, dimethylammonium, trimethylammonium; X=I, Br, Cl) hybrid organic-inorganic materials

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

Mancini, Alessandro; Quadrelli, Paolo; Amoroso, Giuseppe

2016-08-15

In this paper we report the synthesis, the crystal structure and the optical response of APbX{sub 3} (A=MA, DMA, and TMA; X=I, Br) hybrid organic-inorganic materials including some new phases. We observe that as the cation group increases in size, the optical absorption edge shifts to higher energies with energy steps which are systematic and independent on the anion. A linear correlation between the optical bad gap and the tolerance factor has been shown for the series of samples investigated. - Graphical abstract: The crystal structure and the optical response of the two series of hybrid organic-inorganic materials APbX{sub 3}more » (A=MA, DMA, and TMA; X=I, Br), which include some new phases, are reported. A dependence of crystal structure and band-gap with tolerance factor is shown. Display Omitted - Highlights: • DMAPbI{sub 3}, TMAPbI{sub 3} and TMAPbBr{sub 3} are reported as new hybrid organic-inorganic compounds. • Crystal structure and optical properties as a function of the number of methyl groups are provided. • Correlation between structure and optical properties are given as a function of tolerance factor.« less

Stability of nanoclusters in an oxide dispersion strengthened alloy under neutron irradiation

DOE PAGES

Liu, Xiang; Miao, Yinbin; Wu, Yaqiao; ...

2017-06-01

In this paper, we report atom probe tomography results of the nanoclusters in a neutron-irradiated oxide dispersion strengthened alloy. Following irradiation to 5 dpa at target temperatures of 300 °C and 450 °C, fewer large nanoclusters were found and the residual nanoclusters tend to reach an equilibrium Guinier radius of 1.8 nm. With increasing dose, evident decrease in peak oxygen and titanium (but not yttrium) concentrations in the nanoclusters was observed, which was explained by atomic weight, solubility, diffusivity, and chemical bonding arguments. Finally, the chemical modifications indicate the equilibrium size is indeed a balance of two competing processes: radiationmore » enhanced diffusion and collisional dissolution.« less

Neutron kinetics in moderators and SNM detection through epithermal-neutron-induced fissions

NASA Astrophysics Data System (ADS)

Gozani, Tsahi; King, Michael J.

2016-01-01

Extension of the well-established Differential Die Away Analysis (DDAA) into a faster time domain, where more penetrating epithermal neutrons induce fissions, is proposed and demonstrated via simulations and experiments. In the proposed method the fissions stimulated by thermal, epithermal and even higher-energy neutrons are measured after injection of a narrow pulse of high-energy 14 MeV (d,T) or 2.5 MeV (d,D) source neutrons, appropriately moderated. The ability to measure these fissions stems from the inherent correlation of neutron energy and time ("E-T" correlation) during the process of slowing down of high-energy source neutrons in common moderating materials such as hydrogenous compounds (e.g., polyethylene), heavy water, beryllium and graphite. The kinetic behavior following injection of a delta-function-shaped pulse (in time) of 14 MeV neutrons into such moderators is studied employing MCNPX simulations and, when applicable, some simple "one-group" models. These calculations served as a guide for the design of a source moderator which was used in experiments. Qualitative relationships between slowing-down time after the pulse and the prevailing neutron energy are discussed. A laboratory system consisting of a 14 MeV neutron generator, a polyethylene-reflected Be moderator, a liquid scintillator with pulse-shape discrimination (PSD) and a two-parameter E-T data acquisition system was set up to measure prompt neutron and delayed gamma-ray fission signatures in a 19.5% enriched LEU sample. The measured time behavior of thermal and epithermal neutron fission signals agreed well with the detailed simulations. The laboratory system can readily be redesigned and deployed as a mobile inspection system for SNM in, e.g., cars and vans. A strong pulsed neutron generator with narrow pulse (<75 ns) at a reasonably high pulse frequency could make the high-energy neutron induced fission modality a realizable SNM detection technique.

Characterization of neutron calibration fields at the TINT's 50 Ci americium-241/beryllium neutron irradiator

NASA Astrophysics Data System (ADS)

Liamsuwan, T.; Channuie, J.; Ratanatongchai, W.

2015-05-01

Reliable measurement of neutron radiation is important for monitoring and protection in workplace where neutrons are present. Although Thailand has been familiar with applications of neutron sources and neutron beams for many decades, there is no calibration facility dedicated to neutron measuring devices available in the country. Recently, Thailand Institute of Nuclear Technology (TINT) has set up a multi-purpose irradiation facility equipped with a 50 Ci americium-241/beryllium neutron irradiator. The facility is planned to be used for research, nuclear analytical techniques and, among other applications, calibration of neutron measuring devices. In this work, the neutron calibration fields were investigated in terms of neutron energy spectra and dose equivalent rates using Monte Carlo simulations, an in-house developed neutron spectrometer and commercial survey meters. The characterized neutron fields can generate neutron dose equivalent rates ranging from 156 μSv/h to 3.5 mSv/h with nearly 100% of dose contributed by neutrons of energies larger than 0.01 MeV. The gamma contamination was less than 4.2-7.5% depending on the irradiation configuration. It is possible to use the described neutron fields for calibration test and routine quality assurance of neutron dose rate meters and passive dosemeters commonly used in radiation protection dosimetry.

New model of the average neutron and proton pairing gaps

NASA Astrophysics Data System (ADS)

Madland, David G.; Nix, J. Rayford

1988-01-01

By use of the BCS approximation applied to a distribution of dense, equally spaced levels, we derive new expressions for the average neutron pairing gap ¯gD n and average proton pairing gap ¯gD p. These expressions, which contain exponential terms, take into account the dependencies of ¯gD n and ¯gD p upon both the relative neutron excess and shape of the nucleus. The three constants that appear are determined by a least-squares adjustment to experimental pairing gaps obtained by use of fourth-order differences of measured masses. For this purpose we use the 1986 Audi-Wapstra mid-stream mass evaluation and take into account experimental uncertainties. Our new model explains not only the dependencies of ¯gD n and ¯gD p upon relative neutron excess and nuclear shape, but also the experimental result that for medium and heavy nuclei ¯gD n is generally smaller than ¯gD p. We also introduce a new expression for the average residual neutron-proton interaction energy ¯gd that appears in the masses of odd-odd nuclei, and determine the constant that appears by an analogous least-squares adjustment to experimental mass differences. Our new expressions for ¯gD n, ¯gD p and ¯gd should permit extrapolation of these quantities to heavier nuclei and to nuclei farther removed from the valley of β stability than do previous parameterizations.

Fast rotating neutron stars with realistic nuclear matter equation of state

NASA Astrophysics Data System (ADS)

Cipolletta, F.; Cherubini, C.; Filippi, S.; Rueda, J. A.; Ruffini, R.

2015-07-01

We construct equilibrium configurations of uniformly rotating neutron stars for selected relativistic mean-field nuclear matter equations of state (EOS). We compute, in particular, the gravitational mass (M ), equatorial (Req) and polar (Rpol) radii, eccentricity, angular momentum (J ), moment of inertia (I ) and quadrupole moment (M2) of neutron stars stable against mass shedding and secular axisymmetric instability. By constructing the constant frequency sequence f =716 Hz of the fastest observed pulsar, PSR J1748-2446ad, and constraining it to be within the stability region, we obtain a lower mass bound for the pulsar, Mmin=[1.2 - 1.4 ]M⊙ , for the EOS employed. Moreover, we give a fitting formula relating the baryonic mass (Mb) and gravitational mass of nonrotating neutron stars, Mb/M⊙=M /M⊙+(13 /200 )(M /M⊙)2 [or M /M⊙=Mb/M⊙-(1 /20 )(Mb/M⊙)2], which is independent of the EOS. We also obtain a fitting formula, although not EOS independent, relating the gravitational mass and the angular momentum of neutron stars along the secular axisymmetric instability line for each EOS. We compute the maximum value of the dimensionless angular momentum, a /M ≡c J /(G M2) (or "Kerr parameter"), (a /M )max≈0.7 , found to be also independent of the EOS. We then compare and contrast the quadrupole moment of rotating neutron stars with the one predicted by the Kerr exterior solution for the same values of mass and angular momentum. Finally, we show that, although the mass quadrupole moment of realistic neutron stars never reaches the Kerr value, the latter is closely approached from above at the maximum mass value, as physically expected from the no-hair theorem. In particular, the stiffer the EOS, the closer the mass quadrupole moment approaches the value of the Kerr solution.

Response of six neutron survey meters in mixed fields of fast and thermal neutrons.

PubMed

Kim, S I; Kim, B H; Chang, I; Lee, J I; Kim, J L; Pradhan, A S

2013-10-01

Calibration neutron fields have been developed at KAERI (Korea Atomic Energy Research Institute) to study the responses of commonly used neutron survey meters in the presence of fast neutrons of energy around 10 MeV. The neutron fields were produced by using neutrons from the (241)Am-Be sources held in a graphite pile and a DT neutron generator. The spectral details and the ambient dose equivalent rates of the calibration fields were established, and the responses of six neutron survey meters were evaluated. Four single-moderator-based survey meters exhibited an under-responses ranging from ∼9 to 55 %. DINEUTRUN, commonly used in fields around nuclear reactors, exhibited an over-response by a factor of three in the thermal neutron field and an under-response of ∼85 % in the mixed fields. REM-500 (tissue-equivalent proportional counter) exhibited a response close to 1.0 in the fast neutron fields and an under-response of ∼50 % in the thermal neutron field.

Isotope-Identifying neutron reflectometry

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

Nikitenko, Yu. V., E-mail: nikiten@nf.jinr.ru; Petrenko, A. V.; Gundorin, N. A.

2015-07-15

The possibilities of an isotope-indentifying study of layered structures in different regimes of a neutron wave field are considered. The detection of specularly reflected neutrons and secondary radiation (caused by neutron capture) in the form of charged particles, γ quanta, and nuclear fission fragments, as well as neutrons spin-flipped in a noncollinear magnetic field and on nuclei of elements with spin, makes it possible to implement isotope-indentifying neutron reflectometry.

Simple, empirical approach to predict neutron capture cross sections from nuclear masses

NASA Astrophysics Data System (ADS)

Couture, A.; Casten, R. F.; Cakirli, R. B.

2017-12-01

neutron capture cross sections, extending far from stability, including for nuclei of the highest sensitivity to r -process nucleosynthesis.

Dose equivalent neutron dosimeter

DOEpatents

Griffith, Richard V.; Hankins, Dale E.; Tomasino, Luigi; Gomaa, Mohamed A. M.

1983-01-01

A neutron dosimeter is disclosed which provides a single measurements indicating the amount of potential biological damage resulting from the neutron exposure of the wearer, for a wide range of neutron energies. The dosimeter includes a detecting sheet of track etch detecting material such as a carbonate plastic, for detecting higher energy neutrons, and a radiator layer containing conversion material such as .sup.6 Li and .sup.10 B lying adjacent to the detecting sheet for converting moderate energy neutrons to alpha particles that produce tracks in the adjacent detecting sheet. The density of conversion material in the radiator layer is of an amount which is chosen so that the density of tracks produced in the detecting sheet is proportional to the biological damage done by neutrons, regardless of whether the tracks are produced as the result of moderate energy neutrons striking the radiator layer or as the result of higher energy neutrons striking the sheet of track etch material.

New generation non-stationary portable neutron generators for biophysical applications of Neutron Activation Analysis.

PubMed

Marchese, N; Cannuli, A; Caccamo, M T; Pace, C

2017-01-01

Neutron sources are increasingly employed in a wide range of research fields. For some specific purposes an alternative to existing large-scale neutron scattering facilities, can be offered by the new generation of portable neutron devices. This review reports an overview for such recently available neutron generators mainly addressed to biophysics applications with specific reference to portable non-stationary neutron generators applied in Neutron Activation Analysis (NAA). The review reports a description of a typical portable neutron generator set-up addressed to biophysics applications. New generation portable neutron devices, for some specific applications, can constitute an alternative to existing large-scale neutron scattering facilities. Deuterium-Deuterium pulsed neutron sources able to generate 2.5MeV neutrons, with a neutron yield of 1.0×10 6 n/s, a pulse rate of 250Hz to 20kHz and a duty factor varying from 5% to 100%, when combined with solid-state photon detectors, show that this kind of compact devices allow rapid and user-friendly elemental analysis. "This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo". Copyright © 2016 Elsevier B.V. All rights reserved.

Neutron Detector Signal Processing to Calculate the Effective Neutron Multiplication Factor of Subcritical Assemblies

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

Talamo, Alberto; Gohar, Yousry

2016-06-01

This report describes different methodologies to calculate the effective neutron multiplication factor of subcritical assemblies by processing the neutron detector signals using MATLAB scripts. The subcritical assembly can be driven either by a spontaneous fission neutron source (e.g. californium) or by a neutron source generated from the interactions of accelerated particles with target materials. In the latter case, when the particle accelerator operates in a pulsed mode, the signals are typically stored into two files. One file contains the time when neutron reactions occur and the other contains the times when the neutron pulses start. In both files, the timemore » is given by an integer representing the number of time bins since the start of the counting. These signal files are used to construct the neutron count distribution from a single neutron pulse. The built-in functions of MATLAB are used to calculate the effective neutron multiplication factor through the application of the prompt decay fitting or the area method to the neutron count distribution. If the subcritical assembly is driven by a spontaneous fission neutron source, then the effective multiplication factor can be evaluated either using the prompt neutron decay constant obtained from Rossi or Feynman distributions or the Modified Source Multiplication (MSM) method.« less

Convective Excitation of Inertial Modes in Binary Neutron Star Mergers

NASA Astrophysics Data System (ADS)

De Pietri, Roberto; Feo, Alessandra; Font, José A.; Löffler, Frank; Maione, Francesco; Pasquali, Michele; Stergioulas, Nikolaos

2018-06-01

We present the first very long-term simulations (extending up to ˜140 ms after merger) of binary neutron star mergers with piecewise polytropic equations of state and in full general relativity. Our simulations reveal that, at a time of 30-50 ms after merger, parts of the star become convectively unstable, which triggers the excitation of inertial modes. The excited inertial modes are sustained up to several tens of milliseconds and are potentially observable by the planned third-generation gravitational-wave detectors at frequencies of a few kilohertz. Since inertial modes depend on the rotation rate of the star and they are triggered by a convective instability in the postmerger remnant, their detection in gravitational waves will provide a unique opportunity to probe the rotational and thermal state of the merger remnant. In addition, our findings have implications for the long-term evolution and stability of binary neutron star remnants.

Neutron-neutron quasifree scattering in nd breakup at 10 MeV

NASA Astrophysics Data System (ADS)

Malone, R. C.; Crowe, B.; Crowell, A. S.; Cumberbatch, L. C.; Esterline, J. H.; Fallin, B. A.; Friesen, F. Q. L.; Han, Z.; Howell, C. R.; Markoff, D.; Ticehurst, D.; Tornow, W.; Witała, H.

2016-03-01

The neutron-deuteron (nd) breakup reaction provides a rich environment for testing theoretical models of the neutron-neutron (nn) interaction. Current theoretical predictions based on rigorous ab-initio calculations agree well with most experimental data for this system, but there remain a few notable discrepancies. The cross section for nn quasifree (QFS) scattering is one such anomaly. Two recent experiments reported cross sections for this particular nd breakup configuration that exceed theoretical calculations by almost 20% at incident neutron energies of 26 and 25 MeV [1, 2]. The theoretical values can be brought into agreement with these results by increasing the strength of the 1S0 nn potential matrix element by roughly 10%. However, this modification of the nn effective range parameter and/or the 1S0 scattering length causes substantial charge-symmetry breaking in the nucleon-nucleon force and suggests the possibility of a weakly bound di-neutron state [3]. We are conducting new measurements of the cross section for nn QFS in nd breakup. The measurements are performed at incident neutron beam energies below 20 MeV. The neutron beam is produced via the 2H(d, n)3He reaction. The target is a deuterated plastic cylinder. Our measurements utilize time-of-flight techniques with a pulsed neutron beam and detection of the two emitted neutrons in coincidence. A description of our initial measurements at 10 MeV for a single scattering angle will be presented along with preliminary results. Also, plans for measurements at other energies with broad angular coverage will be discussed.

Borner Ball Neutron Detector

NASA Technical Reports Server (NTRS)

2002-01-01

The Bonner Ball Neutron Detector measures neutron radiation. Neutrons are uncharged atomic particles that have the ability to penetrate living tissues, harming human beings in space. The Bonner Ball Neutron Detector is one of three radiation experiments during Expedition Two. The others are the Phantom Torso and Dosimetric Mapping.

The lower cranial nerves: IX, X, XI, XII.

PubMed

Sarrazin, J-L; Toulgoat, F; Benoudiba, F

2013-10-01

The lower cranial nerves innervate the pharynx and larynx by the glossopharyngeal (CN IX) and vagus (CN X) (mixed) nerves, and provide motor innervation of the muscles of the neck by the accessory nerve (CN XI) and the tongue by the hypoglossal nerve (CN XII). The symptomatology provoked by an anomaly is often discrete and rarely in the forefront. As with all cranial nerves, the context and clinical examinations, in case of suspicion of impairment of the lower cranial nerves, are determinant in guiding the imaging. In fact, the impairment may be located in the brain stem, in the peribulbar cisterns, in the foramens or even in the deep spaces of the face. The clinical localization of the probable seat of the lesion helps in choosing the adapted protocol in MRI and eventually completes it with a CT-scan. In the bulb, the intra-axial pathology is dominated by brain ischemia (in particular, with Wallenberg syndrome) and multiple sclerosis. Cisternal pathology is tumoral with two tumors, schwannoma and meningioma. The occurrence is much lower than in the cochleovestibular nerves as well as the leptomeningeal nerves (infectious, inflammatory or tumoral). Finally, foramen pathology is tumoral with, outside of the usual schwannomas and meningiomas, paragangliomas. For radiologists, fairly hesitant to explore these lower cranial pairs, it is necessary to be familiar with (or relearn) the anatomy, master the exploratory technique and be aware of the diagnostic possibilities. Copyright © 2013 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

Introduction to neutron stars

NASA Astrophysics Data System (ADS)

Lattimer, James M.

2015-02-01

Neutron stars contain the densest form of matter in the present universe. General relativity and causality set important constraints to their compactness. In addition, analytic GR solutions are useful in understanding the relationships that exist among the maximum mass, radii, moments of inertia, and tidal Love numbers of neutron stars, all of which are accessible to observation. Some of these relations are independent of the underlying dense matter equation of state, while others are very sensitive to the equation of state. Recent observations of neutron stars from pulsar timing, quiescent X-ray emission from binaries, and Type I X-ray bursts can set important constraints on the structure of neutron stars and the underlying equation of state. In addition, measurements of thermal radiation from neutron stars has uncovered the possible existence of neutron and proton superfluidity/superconductivity in the core of a neutron star, as well as offering powerful evidence that typical neutron stars have significant crusts. These observations impose constraints on the existence of strange quark matter stars, and limit the possibility that abundant deconfined quark matter or hyperons exist in the cores of neutron stars.

Introduction to neutron stars

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

Lattimer, James M.

Neutron stars contain the densest form of matter in the present universe. General relativity and causality set important constraints to their compactness. In addition, analytic GR solutions are useful in understanding the relationships that exist among the maximum mass, radii, moments of inertia, and tidal Love numbers of neutron stars, all of which are accessible to observation. Some of these relations are independent of the underlying dense matter equation of state, while others are very sensitive to the equation of state. Recent observations of neutron stars from pulsar timing, quiescent X-ray emission from binaries, and Type I X-ray bursts canmore » set important constraints on the structure of neutron stars and the underlying equation of state. In addition, measurements of thermal radiation from neutron stars has uncovered the possible existence of neutron and proton superfluidity/superconductivity in the core of a neutron star, as well as offering powerful evidence that typical neutron stars have significant crusts. These observations impose constraints on the existence of strange quark matter stars, and limit the possibility that abundant deconfined quark matter or hyperons exist in the cores of neutron stars.« less

Accelerator-based neutron source for boron neutron capture therapy (BNCT) and method

DOEpatents

Yoon, W.Y.; Jones, J.L.; Nigg, D.W.; Harker, Y.D.

1999-05-11

A source for boron neutron capture therapy (BNCT) comprises a body of photoneutron emitter that includes heavy water and is closely surrounded in heat-imparting relationship by target material; one or more electron linear accelerators for supplying electron radiation having energy of substantially 2 to 10 MeV and for impinging such radiation on the target material, whereby photoneutrons are produced and heat is absorbed from the target material by the body of photoneutron emitter. The heavy water is circulated through a cooling arrangement to remove heat. A tank, desirably cylindrical or spherical, contains the heavy water, and a desired number of the electron accelerators circumferentially surround the tank and the target material as preferably made up of thin plates of metallic tungsten. Neutrons generated within the tank are passed through a surrounding region containing neutron filtering and moderating materials and through neutron delimiting structure to produce a beam or beams of epithermal neutrons normally having a minimum flux intensity level of 1.0{times}10{sup 9} neutrons per square centimeter per second. Such beam or beams of epithermal neutrons are passed through gamma ray attenuating material to provide the required epithermal neutrons for BNCT use. 3 figs.

Accelerator-based neutron source for boron neutron capture therapy (BNCT) and method

DOEpatents

Yoon, Woo Y.; Jones, James L.; Nigg, David W.; Harker, Yale D.

1999-01-01

A source for boron neutron capture therapy (BNCT) comprises a body of photoneutron emitter that includes heavy water and is closely surrounded in heat-imparting relationship by target material; one or more electron linear accelerators for supplying electron radiation having energy of substantially 2 to 10 MeV and for impinging such radiation on the target material, whereby photoneutrons are produced and heat is absorbed from the target material by the body of photoneutron emitter. The heavy water is circulated through a cooling arrangement to remove heat. A tank, desirably cylindrical or spherical, contains the heavy water, and a desired number of the electron accelerators circumferentially surround the tank and the target material as preferably made up of thin plates of metallic tungsten. Neutrons generated within the tank are passed through a surrounding region containing neutron filtering and moderating materials and through neutron delimiting structure to produce a beam or beams of epithermal neutrons normally having a minimum flux intensity level of 1.0.times.10.sup.9 neutrons per square centimeter per second. Such beam or beams of epithermal neutrons are passed through gamma ray attenuating material to provide the required epithermal neutrons for BNCT use.

NeutronSTARS: A segmented neutron and charged particle detector for low-energy reaction studies

DOE PAGES

Akindele, O. A.; Casperson, R. J.; Wang, B. S.; ...

2017-08-10

NeutronSTARS (Neutron-S ilicon T elescope A rray for R eaction S tudies) consists of 2.2-tons of gadolinium-doped liquid scintillator for neutron detection and large area silicon detectors for charged particle identification. This detector array is intended for low-energy-nuclear-reaction measurements that result in the emission of neutrons such as and fission. This paper describes the NeutronSTARS experimental setup, calibration, and the array’s response to neutral and charged particles.

Neutron Scattering Announcements

Science.gov Websites

will be added. We encourage everyone interested in neutron scattering to take full advantage of this neutron source ESS. After an initial layout phase using analytical considerations further assessment of Home Page | Facilities | Reference | Software | Conferences | Announcements | Mailing Lists Neutron

Double-layer neutron shield design as neutron shielding application

NASA Astrophysics Data System (ADS)

Sariyer, Demet; Küçer, Rahmi

2018-02-01

The shield design in particle accelerators and other high energy facilities are mainly connected to the high-energy neutrons. The deep penetration of neutrons through massive shield has become a very serious problem. For shielding to be efficient, most of these neutrons should be confined to the shielding volume. If the interior space will become limited, the sufficient thickness of multilayer shield must be used. Concrete and iron are widely used as a multilayer shield material. Two layers shield material was selected to guarantee radiation safety outside of the shield against neutrons generated in the interaction of the different proton energies. One of them was one meter of concrete, the other was iron-contained material (FeB, Fe2B and stainless-steel) to be determined shield thicknesses. FLUKA Monte Carlo code was used for shield design geometry and required neutron dose distributions. The resulting two layered shields are shown better performance than single used concrete, thus the shield design could leave more space in the interior shielded areas.

Structure of Aqueous Trehalose Solution by Neutron Diffraction and Structural Modeling.

PubMed

Olsson, Christoffer; Jansson, Helén; Youngs, Tristan; Swenson, Jan

2016-12-15

The molecular structure of an aqueous solution of the disaccharide trehalose (C 12 H 22 O 11 ) has been studied by neutron diffraction and empirical potential structure refinement modeling. Six different isotope compositions with 33 wt % trehalose (corresponding to 38 water molecules per trehalose molecule) were measured to ensure that water-water, trehalose-water, and trehalose-trehalose correlations were accurately determined. In fact, this is the first neutron diffraction study of an aqueous trehalose solution in which also the nonexchangeable hydrogen atoms in trehalose are deuterated. With this approach, it was possible to determine that (1) there is a substantial hydrogen bonding between trehalose and water (∼11 hydrogen bonds per trehalose molecule), which is in contrast to previous neutron diffraction studies, and (2) there is no tendency of clustering of trehalose, in contrast to what is generally observed by molecular dynamics simulations and experimentally found for other disaccharides. Thus, the results give the structural picture that trehalose prefers to interact with water and participate in a hydrogen-bonded network. This strong network character of the solution might be one of the key reasons for its extraordinary stabilization effect on biological materials.

Rapidly rotating neutron stars in general relativity: Realistic equations of state

NASA Technical Reports Server (NTRS)

Cook, Gregory B.; Shapiro, Stuart L.; Teukolsky, Saul A.

1994-01-01

We construct equilibrium sequences of rotating neutron stars in general relativity. We compare results for 14 nuclear matter equations of state. We determine a number of important physical parameters for such stars, including the maximum mass and maximum spin rate. The stability of the configurations to quasi-radial perturbations is assessed. We employ a numerical scheme particularly well suited to handle rapid rotation and large departures from spherical symmetry. We provide an extensive tabulation of models for future reference. Two classes of evolutionary sequences of fixed baryon rest mass and entropy are explored: normal sequences, which behave very much like Newtonian sequences, and supramassive sequences, which exist for neutron stars solely because of general relativistic effects. Adiabatic dissipation of energy and angular momentum causes a star to evolve in quasi-stationary fashion along an evolutionary sequence. Supramassive sequences have masses exceeding the maximum mass of a nonrotating neutron star. A supramassive star evolves toward eventual catastrophic collapse to a black hole. Prior to collapse, the star actually spins up as it loses angular momentum, an effect that may provide an observable precursor to gravitational collapse to a black hole.

Oversight Hearings on the Implementation of Title XI, Public Law 95-561: Problems in the BIA Portland Area. Hearings before the Subcommittee on Elementary, Secondary, and Vocational Education of the Committee on Education and Labor, House of Representatives, Ninety-Sixth Congress, Second Session (July 28-29, 1980).

ERIC Educational Resources Information Center

Congress of the U.S., Washington, DC. House Committee on Education and Labor.

The Subcommittee on Elementary, Secondary, and XI, Public Law 95-561: Problems in the BIA Portland Area. issue of administrative funds (Element 10, Title XI, Basic Indian Education Act) to be allotted to the Portland area of the Bureau of Indian Affairs (BIA). Maxine Edmo, president of the Advocates for Indian Education educational arm of the…

Non-destructive diagnostics of irradiated materials using neutron scattering from pulsed neutron sources

NASA Astrophysics Data System (ADS)

Korenev, Sergey; Sikolenko, Vadim

2004-09-01

The advantage of neutron-scattering studies as compared to the standard X-ray technique is the high penetration of neutrons that allow us to study volume effects. The high resolution of instrumentation on the basis neutron scattering allows measurement of the parameters of lattice structure with high precision. We suggest the use of neutron scattering from pulsed neutron sources for analysis of materials irradiated with pulsed high current electron and ion beams. The results of preliminary tests using this method for Ni foils that have been studied by neutron diffraction at the IBR-2 (Pulsed Fast Reactor at Joint Institute for Nuclear Research) are presented.

Inter-annual variability of wintertime PM2.5 chemical composition in Xi'an, China: Evidences of changing source emissions.

PubMed

Xu, Hongmei; Cao, Junji; Chow, Judith C; Huang, R-J; Shen, Zhenxing; Chen, L W Antony; Ho, Kin Fai; Watson, John G

2016-03-01

Chemical characteristics of PM2.5 in Xi'an in wintertime of 2006, 2008, and 2010 were investigated. Markers of OC2, EC1, and NO3(-)/SO4(2-) ratio were calculated to investigate the changes in PM2.5 emission sources over the 5-year period. Positive matrix factorization (PMF) model was used to identify and quantify the main sources of PM2.5 and their contributions. The results showed that coal combustion, motor vehicular emissions, fugitive dust, and secondary inorganic aerosol accounted for more than 80% of PM2.5 mass. The importance of these major sources to the PM2.5 mass varied yearly: coal combustion was the largest contributor (31.2% ± 5.2%), followed by secondary inorganic aerosol (20.9% ± 5.2%) and motor vehicular emissions (19.3% ± 4.8%) in 2006; the order was still coal combustion emissions (27.6% ± 3.4%), secondary inorganic aerosol (23.2% ± 6.9%), and motor vehicular emissions (20.9% ± 4.6%) in 2008; while coal combustion emission further decreased (24.1% ± 3.1%) with fugitive dust (19.4% ± 5.5%) increasing in 2010. The changes in PM2.5 chemical compositions and source contributions can be attributed to the social and economic developments in Xi'an, China, including energy structure adjustment, energy consumption, the expansion of civil vehicles, and the increase of urban construction activities. Copyright © 2015 Elsevier B.V. All rights reserved.

Magnetic trapping of neutrons

PubMed

Huffman; Brome; Butterworth; Coakley; Dewey; Dzhosyuk; Golub; Greene; Habicht; Lamoreaux; Mattoni; McKinsey; Wietfeldt; Doyle

2000-01-06

Accurate measurement of the lifetime of the neutron (which is unstable to beta decay) is important for understanding the weak nuclear force and the creation of matter during the Big Bang. Previous measurements of the neutron lifetime have mainly been limited by certain systematic errors; however, these could in principle be avoided by performing measurements on neutrons stored in a magnetic trap. Neutral-particle and charged-particle traps are widely used for studying both composite and elementary particles, because they allow long interaction times and isolation of particles from perturbing environments. Here we report the magnetic trapping of neutrons. The trapping region is filled with superfluid 4He, which is used to load neutrons into the trap and as a scintillator to detect their decay. Neutrons in the trap have a lifetime of 750(+330)(-200) seconds, mainly limited by their beta decay rather than trap losses. Our experiment verifies theoretical predictions regarding the loading process and magnetic trapping of neutrons. Further refinement of this method should lead to improved precision in the neutron lifetime measurement.

Measurement of the most exotic beta-delayed neutron emitters at N=50 and N=126

NASA Astrophysics Data System (ADS)

Dillmann, Iris

2017-09-01

Beta-delayed neutron (βn)-emission will be the dominant decay mechanism of neutron-rich nuclei and plays an important role in the stellar nucleosynthesis of heavy elements in the ``r process''. It leads to a detour of the material β-decaying back to stability and the released neutrons increase the neutron-to-seed ratio, and are re-captured during the freeze-out phase and thus influence the final solar r-abundance curve. Thus the neutron branching ratio of very neutron-rich isotopes is a crucial parameter in astrophysical simulations. In addition, β-decay half-lives can be deduced from the time-dependent detection of βn's. I will talk about two recent experimental campaigns. The neutron detector BELEN was used at GSI Darmstadt to measure half-lives and neutron-branching ratios of the heaviest presently accessible βn-emitters at N=126. For isotopes between 204Au and 220Bi nine half-lives and eight neutron-branching ratios were measured for the first time and provide an important input for benchmarking theoretical models in this mass region. Its successor is the BRIKEN detector (``Beta-delayed neutron measurements at RIKEN for nuclear structure, astrophysics, and applications''), the most efficient neutron detector used so far for nuclear structure studies. In conjunction with two clover detectors and the ``Advanced Implantation Detector Array'' (AIDA) the setup has been used a few months ago to measure the most neutron-rich isotopes around 78Ni, 132Sn, and the Rare Earth Region. Some preliminary results are shown from the campaign covering the 78Ni region where the neutron-branching ratio of 78Ni and 28 more isotopes were measured for the first time, as well as the half-lives of 20 isotopes. The BRIKEN campaign aims to (re-)measure almost all βn-emitters between 76Co and 167Eu, many of them for the first time. An extension of the campaign to lighter masses is planned. This work has been supported by the NSERC and NRC in Canada, the US DOE, the Spanish

Grazing Incidence Neutron Optics

NASA Technical Reports Server (NTRS)

Gubarev, Mikhail V. (Inventor); Ramsey, Brian D. (Inventor); Engelhaupt, Darell E. (Inventor)

2013-01-01

Neutron optics based on the two-reflection geometries are capable of controlling beams of long wavelength neutrons with low angular divergence. The preferred mirror fabrication technique is a replication process with electroform nickel replication process being preferable. In the preliminary demonstration test an electroform nickel optics gave the neutron current density gain at the focal spot of the mirror at least 8 for neutron wavelengths in the range from 6 to 20.ANG.. The replication techniques can be also be used to fabricate neutron beam controlling guides.

Grazing incidence neutron optics

NASA Technical Reports Server (NTRS)

Gubarev, Mikhail V. (Inventor); Ramsey, Brian D. (Inventor); Engelhaupt, Darell E. (Inventor)

2012-01-01

Neutron optics based on the two-reflection geometries are capable of controlling beams of long wavelength neutrons with low angular divergence. The preferred mirror fabrication technique is a replication process with electroform nickel replication process being preferable. In the preliminary demonstration test an electroform nickel optics gave the neutron current density gain at the focal spot of the mirror at least 8 for neutron wavelengths in the range from 6 to 20 .ANG.. The replication techniques can be also be used to fabricate neutron beam controlling guides.

Performance verification of an epithermal neutron flux monitor using accelerator-based BNCT neutron sources

NASA Astrophysics Data System (ADS)

Guan, X.; Murata, I.; Wang, T.

2017-09-01

The performance of an epithermal neutron flux monitor developed for boron neutron capture therapy (BNCT) is verified by Monte Carlo simulations using accelerator-based neutron sources (ABNSs). The results indicate that the developed epithermal neutron flux monitor works well and it can be efficiently used in practical applications to measure the epithermal neutron fluxes of ABNSs in a high accuracy.

Recent Advances in Neutron Physics

ERIC Educational Resources Information Center

Feshbach, Herman; Sheldon, Eric

1977-01-01

Discusses new studies in neutron physics within the last decade, such as ultracold neutrons, neutron bottles, resonance behavior, subthreshold fission, doubly radiative capture, and neutron stars. (MLH)

Failure of a new protocol to improve treatment results in paediatric lymphoblastic leukaemia: lessons from the UK Medical Research Council trials UKALL X and UKALL XI.

PubMed

Chessells, Judith M; Harrison, Georgina; Richards, Susan M; Gibson, Brenda E; Bailey, Clifford C; Hill, Frank G H; Hann, Ian M

2002-08-01

The impact of various types of intensification therapy was examined in a cohort of 3617 children aged 1-14 years with acute lymphoblastic leukaemia (ALL) enrolled in the Medical Research Council (MRC) UKALL X (1985-90) and UKALL XI (1990-97) trials. UKALL XI was modified in 1992 to incorporate the "best arm" of UKALL X with two 5-d intensification blocks at 5 and 20 weeks, and an additional randomization in respect of a third intensification at 35 weeks but omission of two consecutive injections of daunorubicin during induction. All children were eligible for randomization irrespective of risk group. The impact of the various types of intensification therapy was examined in a stratified analysis. At a median follow up of 102 months, both trials had an identical event-free survival of 61% (95% CI 58-63%) at 8 years. Survival at 8 years in UKALL XI was significantly better in than in UKALL X, 81% (79-83%) compared with 74% (72-76%) (P = < 0.001), owing to improved management of relapse. There was a highly significant trend in reduction of the number of relapses and deaths with increased intensity of therapy both for children with initial leucocyte count < 50 x 10(9)/l (P = < 0.001) and > or = 50 x 10(9)/l (P = 0.002). Introduction of a third late intensification block compensated for omission of anthracyclines during induction but produced little additional benefit. These results show, in a large cohort of patients, that minor modifications of therapy may influence relapse rate and obviate the benefit of previous randomized trials. The failure to adapt treatment for higher risk children contributed to these disappointing results.

Characterization of silicon carbide and diamond detectors for neutron applications

NASA Astrophysics Data System (ADS)

Hodgson, M.; Lohstroh, A.; Sellin, P.; Thomas, D.

2017-10-01

The presence of carbon atoms in silicon carbide and diamond makes these materials ideal candidates for direct fast neutron detectors. Furthermore the low atomic number, strong covalent bonds, high displacement energies, wide bandgap and low intrinsic carrier concentrations make these semiconductor detectors potentially suitable for applications where rugged, high-temperature, low-gamma-sensitivity detectors are required, such as active interrogation, electronic personal neutron dosimetry and harsh environment detectors. A thorough direct performance comparison of the detection capabilities of semi-insulating silicon carbide (SiC-SI), single crystal diamond (D-SC), polycrystalline diamond (D-PC) and a self-biased epitaxial silicon carbide (SiC-EP) detector has been conducted and benchmarked against a commercial silicon PIN (Si-PIN) diode, in a wide range of alpha (Am-241), beta (Sr/Y-90), ionizing photon (65 keV to 1332 keV) and neutron radiation fields (including 1.2 MeV to 16.5 MeV mono-energetic neutrons, as well as neutrons from AmBe and Cf-252 sources). All detectors were shown to be able to directly detect and distinguish both the different radiation types and energies by using a simple energy threshold discrimination method. The SiC devices demonstrated the best neutron energy discrimination ratio (E\\max (n=5 MeV)/E\\max (n=1 MeV)  ≈5), whereas a superior neutron/photon cross-sensitivity ratio was observed in the D-PC detector (E\\max (AmBe)/E\\max (Co-60)  ≈16). Further work also demonstrated that the cross-sensitivity ratios can be improved through use of a simple proton-recoil conversion layer. Stability issues were also observed in the D-SC, D-PC and SiC-SI detectors while under irradiation, namely a change of energy peak position and/or count rate with time (often referred to as the polarization effect). This phenomenon within the detectors was non-debilitating over the time period tested (> 5 h) and, as such, stable operation was

Neutron spectrum determination in a sub-critical assembly using the multi-disc neutron activation technique

NASA Astrophysics Data System (ADS)

Koseoglou, P.; Vagena, E.; Stoulos, S.; Manolopoulou, M.

2016-09-01

Neutron spectrum of the sub-critical nuclear assembly-reactor of Aristotle University of Thessaloniki was measured at three radial distances from the reactor core. The neutron activation technique was applied irradiating 15 thick foils - disc of various elements at each position. The data of 38 (n, γ), (n, p) and (n, α) reactions were analyzed for specific activity determination. Discs instead of foils were used due to the relevant low neutron flux, so the gamma self-absorption as well as the neutron self-shielding factors has been calculated using GEANT simulations in order to determine the activity induced. The specific activities calculated for all isotopes studied were the input to the SANDII code, which was built specifically for the neutron spectrum de-convolution when the neutron activation technique is used. For the optimization of the results a technique was applied in order to minimize the influence of the initial-"guessed" spectrum shape SANDII uses. The neutron spectrum estimated presents a peak in the regions of (i) thermal neutrons ranged between 0.001 and 1 eV peaking at neutron energy ∼0.1 eV and (ii) fast neutrons ranged between 0.1 and 20 MeV peaking at neutron energy ∼1.2 MeV. The reduction of thermal neutrons is higher than the fast one as the distance from the reactor core increases since thermal neutrons capture by natural U-fuel has higher cross section than the fast neutrons.

Dose-equivalent neutron dosimeter

DOEpatents

Griffith, R.V.; Hankins, D.E.; Tomasino, L.; Gomaa, M.A.M.

1981-01-07

A neutron dosimeter is disclosed which provides a single measurement indicating the amount of potential biological damage resulting from the neutron exposure of the wearer, for a wide range of neutron energies. The dosimeter includes a detecting sheet of track etch detecting material such as a carbonate plastic, for detecting higher energy neutrons, and a radiator layer contaning conversion material such as /sup 6/Li and /sup 10/B lying adjacent to the detecting sheet for converting moderate energy neutrons to alpha particles that produce tracks in the adjacent detecting sheet.

Neutron Scattering Web

Science.gov Websites

Neutron Scattering Home Page A new portal for neutron scattering has just been established at neutronsources.org. The information contained here in the Neutron Scattering Web has been transferred to the new site . We will leave the current content here for archival purposes but no new content will be added. We

Consensus Report of the XI Congress of the Spanish Society of Odontology for the Handicapped and Special Patients

PubMed Central

Cabrerizo-Merino, Carmen; Cutando-Soriano, Antonio; Giménez-Prats, María J.; Silvestre-Donat, Farncisco J.; Tomás-Carmona, Inmaculada

2014-01-01

This article summarizes the findings of consensus of the XI congress of the SEOEME. All of these conclusions are referring to the review articles responsible to the general rapporteurs in order to bringing up to date knowledge with regard to the use of implants in patients medically compromised and with special needs and, in the dental management of autism and cerebral palsy, in the dental treatment of patients with genetic and adquired haematological disorders, the dental implications of cardiovascular disease and hospital dentistry. Key words:Autism, cardiovascular diseases, cerebral palsy, dental implants, disabled patients, haematological disorders, hospital dentistry. PMID:24608224

Design of a boron neutron capture enhanced fast neutron therapy assembly

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

Wang, Zhonglu

The use of boron neutron capture to boost tumor dose in fast neutron therapy has been investigated at several fast neutron therapy centers worldwide. This treatment is termed boron neutron capture enhanced fast neutron therapy (BNCEFNT). It is a combination of boron neutron capture therapy (BNCT) and fast neutron therapy (FNT). It is believed that BNCEFNT may be useful in the treatment of some radioresistant brain tumors, such as glioblastoma multiform (GBM). A boron neutron capture enhanced fast neutron therapy assembly has been designed for the Fermilab Neutron Therapy Facility (NTF). This assembly uses a tungsten filter and collimator nearmore » the patient's head, with a graphite reflector surrounding the head to significantly increase the dose due to boron neutron capture reactions. The assembly was designed using Monte Carlo radiation transport code MCNP version 5 for a standard 20x20 cm 2 treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm 2 collimation was 21.9% per 100-ppm 10B for a 5.0-cm tungsten filter and 29.8% for a 8.5-cm tungsten filter. The corresponding dose rate for the 5.0-cm and 8.5-cm thick filters were 0.221 and 0.127 Gy/min, respectively; about 48.5% and 27.9% of the dose rate of the standard 10x10 cm 2 fast neutron treatment beam. To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm 2 collimator. Five 1.0-cm thick 20x20 cm 2 tungsten plates were used to obtain different filter thicknesses and graphite bricks/blocks were used to form a reflector. Measurements of the dose enhancement of the simplified assembly in a water-filled head phantom were performed using a pair of tissue-equivalent ion chambers. One of the ion chambers is loaded with 1000-ppm natural boron (184-ppm 10B) to measure dose due to boron neutron capture. The measured dose enhancement at 5.0-cm depth in the head phantom for the 5

Signatures of Heavy Element Production in Neutron Star Mergers

NASA Astrophysics Data System (ADS)

Barnes, Jennifer

2018-06-01

Compact object mergers involving at least one neutron star have long been theorized to be sites of astrophysical nucleosynthesis via rapid neutron capture (the r-process). The observation in light and gravitational waves of the first neutron star merger (GW1701817) this past summer provided a stunning confirmation of this theory. Electromagnetic emission powered by the radioactive decay of freshly synthesized nuclei from mergers encodes information about the composition burned by the r-process, including whether a particular merger event synthesized the heaviest nuclei along the r-process path, or froze out at lower mass number. However, efforts to model the emission in detail must still contend with many uncertainties. For instance, the uncertain nuclear masses far from the valley of stability influence the final composition burned by the r-process, as will weak interactions operating in the merger’s immediate aftermath. This in turn can affect the color electromagnetic emission. Understanding the details of these transients’ spectra will also require a detailed accounting the electronic transitions of r-process elements and ions, in order to identify the strong transitions that underlie spectral formation. This talk will provide an overview of our current understanding of radioactive transients from mergers, with an emphasis on the role of experiment in providing critical inputs for models and reducing uncertainty.

Relativistic stellar stability: An empirical approach

NASA Technical Reports Server (NTRS)

Ni, W.

1972-01-01

The PPN formalism which encompasses the post-Newtonian limit of nearly every metric theory of gravity is used to analyze stellar stability. This analysis enables one to infer, for any given gravitation theory, the extent to which post-Newtonian effects induce instabilities in white dwarfs, in neutron stars, and in supermassive stars. It also reveals the extent to which our current empirical knowledge of post-Newtonian gravity (based on solar-system experiments) actually guarantees that relativistic instabilities exist. In particular, it shows that: (1) for conservative theories of gravity, current solar-system experiments guarantee that the critical adiabatic index, for the stability of stars against radial pulsations exceeds the Newtonian value of 4/3 and (2) for nonconservative theories, current experiments do not permit any firm conclusion about the sign of the critical adiabatic index, and (3) in the PPN approximation to every metric theory, the standard Schwarzschild criterion for convection is valid.

Pulsed neutron detector

DOEpatents

Robertson, deceased, J. Craig; Rowland, Mark S.

1989-03-21

A pulsed neutron detector and system for detecting low intensity fast neutron pulses has a body of beryllium adjacent a body of hydrogenous material the latter of which acts as a beta particle detector, scintillator, and moderator. The fast neutrons (defined as having En>1.5 MeV) react in the beryllium and the hydrogenous material to produce larger numbers of slow neutrons than would be generated in the beryllium itself and which in the beryllium generate hellium-6 which decays and yields beta particles. The beta particles reach the hydrogenous material which scintillates to yield light of intensity related to the number of fast neutrons. A photomultiplier adjacent the hydrogenous material (scintillator) senses the light emission from the scintillator. Utilization means, such as a summing device, sums the pulses from the photo-multiplier for monitoring or other purposes.

Proposal for the Simultaneous Measurement of the Neutron-Neutron and Neutron-Proton Quasi-Free Scattering Cross Section via the Neutron-Deuteron Breakup Reaction at E n = 19 MeV

NASA Astrophysics Data System (ADS)

Tornow, W.; Howell, C. R.; Crowell, A. S.

2013-12-01

In order to confirm or refute the present discrepancy between data and calculation for the neutron-neutron quasi-free scattering cross section in the neutron-deuteron breakup reaction, we describe a new experimental approach currently being pursued at TUNL.

Effect of neutron energy and fluence on deuterium retention behaviour in neutron irradiated tungsten

NASA Astrophysics Data System (ADS)

Fujita, Hiroe; Yuyama, Kenta; Li, Xiaochun; Hatano, Yuji; Toyama, Takeshi; Ohta, Masayuki; Ochiai, Kentaro; Yoshida, Naoaki; Chikada, Takumi; Oya, Yasuhisa

2016-02-01

Deuterium (D) retention behaviours for 14 MeV neutron irradiated tungsten (W) and fission neutron irradiated W were evaluated by thermal desorption spectroscopy (TDS) to elucidate the correlation between D retention and defect formation by different energy distributions of neutrons in W at the initial stage of fusion reactor operation. These results were compared with that for Fe2+ irradiated W with various damage concentrations. Although dense vacancies and voids within the shallow region near the surface were introduced by Fe2+ irradiation, single vacancies with low concentration were distributed throughout the sample for 14 MeV neutron irradiated W. Only the dislocation loops were introduced by fission neutron irradiation at low neutron fluence. The desorption peak of D for fission neutron irradiated W was concentrated at low temperature region less than 550 K, but that for 14 MeV neutron irradiated W was extended toward the higher temperature side due to D trapping by vacancies. It can be said that the neutron energy distribution could have a large impact on irradiation defect formation and the D retention behaviour.

Active Neutron-Based Interrogation System with D-D Neutron Source for Detection of Special Nuclear Materials

NASA Astrophysics Data System (ADS)

Takahashi, Y.; Misawa, T.; Yagi, T.; Pyeon, C. H.; Kimura, M.; Masuda, K.; Ohgaki, H.

2015-10-01

The detection of special nuclear materials (SNM) is an important issue for nuclear security. The interrogation systems used in a sea port and an airport are developed in the world. The active neutron-based interrogation system is the one of the candidates. We are developing the active neutron-based interrogation system with a D-D fusion neutron source for the nuclear security application. The D-D neutron source is a compact discharge-type fusion neutron source called IEC (Inertial-Electrostatic Confinement fusion) device which provides 2.45 MeV neutrons. The nuclear materials emit the highenergy neutrons by fission reaction. High-energy neutrons with energies over 2.45 MeV amount to 30% of all the fission neutrons. By using the D-D neutron source, the detection of SNMs is considered to be possible with the attention of fast neutrons if there is over 2.45 MeV. Ideally, neutrons at En>2.45 MeV do not exist if there is no nuclear materials. The detection of fission neutrons over 2.45 MeV are hopeful prospect for the detection of SNM with a high S/N ratio. In the future, the experiments combined with nuclear materials and a D-D neutron source will be conducted. Furthermore, the interrogation system will be numerically investigated by using nuclear materials, a D-D neutron source, and a steel container.

Can the starpatch on Xi Bootis A be explained by using tangential flows?

NASA Technical Reports Server (NTRS)

Toner, Clifford G.; Labonte, Barry J.

1991-01-01

It is demonstrated that a modification of the starpatch model of Toner and Gray (1988), using tangential flows instead of an enhanced granulation velocity dispersion within the patch, is very successful at reproducing both the observed line asymmetry and the line broadening variations observed in the G8 dwarf Xi Boo A. Areal coverage of 10 percent + or - 3 percent of the visible disk, latitude 30 deg + or - 4 deg, mean brightness 0.85 + or - 0.05 relative to the 'quiet' photosphere, mean tangential flow velocities of 8.0 + or - 1.5 km/s, and dispersions about the mean of 8/0 + or - 2.0 km/s are inferred for the patch. A feature at a latitude of about 30 deg is inferred which covers about 10 percent of the visible disk and is 10-20 percent fainter than the rest of the photosphere. It is inferred that 70-80 percent of the patch is penumbra.

The Early Stage of Neutron Tomography for Cultural Heritage Study in Thailand

NASA Astrophysics Data System (ADS)

Khaweerat, S.; Ratanatongchai, W.; S. Wonglee; Schillinger, B.

In parallel to the upgrade of neutron imaging facility at TRR-1/M1 since 2015, the practice on image processing software has led to implementation of neutron tomography (NT). The current setup provides a thermal neutron flux of 1.08×106 cm-2sec-1 at the exposure position. In general, the sample was fixed on a plate at the top of rotary stage controlled by Labview 2009 Version 9.0.1. The incremental step can be adjusted from 0.45 to 7.2 degree. A 16 bit CCD camera assembled with a Nikkor 50 mm f/1.2 lens was used to record light from 6LiF/ZnS (green) neutron converter screen. The exposure time for each shot was 60 seconds, resulting in the acquisition time of approximately three hours for completely turning the sample around. Afterwards, the batch of two dimensional neutron images of the sample was read into the reconstruction and visualization software Octopus reconstruction 8.8 and Octopus visualization 2.0, respectively. The results revealed that the system alignment is important. Maintaining the stability of heavy sample at every particular angle of rotation is important. Previous alignment showed instability of the supporting plane while tilting the sample. This study showed that the sample stage should be replaced. Even though the NT is a lengthy process and involves large data processing, it offers an opportunity to better understand features of an object in more details than with neutron radiography. The digital NT also allows us to separate inner features that appear superpositioned in radiography by cross-sectioning the 3D data set of an object without destruction. As a result, NT is a significant tool for revealing hidden information included in the inner structure of cultural heritage objects, providing great benefits in archaeological study, conservation process and authenticity investigating.

High intensity, pulsed thermal neutron source

DOEpatents

Carpenter, J.M.

1973-12-11

This invention relates to a high intensity, pulsed thermal neutron source comprising a neutron-producing source which emits pulses of fast neutrons, a moderator block adjacent to the last neutron source, a reflector block which encases the fast neutron source and the moderator block and has a thermal neutron exit port extending therethrough from the moderator block, and a neutron energy- dependent decoupling reflector liner covering the interior surfaces of the thermal neutron exit port and surrounding all surfaces of the moderator block except the surface viewed by the thermal neutron exit port. (Official Gazette)

Crystal Chemistry of Three-component White Dwarfs and Neutron Star Crusts: Phase Stability, Phase Stratification, and Physical Properties

NASA Astrophysics Data System (ADS)

Engstrom, T. A.; Yoder, N. C.; Crespi, V. H.

2016-02-01

A systematic search for multicomponent crystal structures is carried out for five different ternary systems of nuclei in a polarizable background of electrons, representative of accreted neutron star crusts and some white dwarfs. Candidate structures are “bred” by a genetic algorithm and optimized at constant pressure under the assumption of linear response (Thomas-Fermi) charge screening. Subsequent phase equilibria calculations reveal eight distinct crystal structures in the T = 0 bulk phase diagrams, five of which are complicated multinary structures not previously predicted in the context of compact object astrophysics. Frequent instances of geometrically similar but compositionally distinct phases give insight into structural preferences of systems with pairwise Yukawa interactions, including and extending to the regime of low-density colloidal suspensions made in a laboratory. As an application of these main results, we self-consistently couple the phase stability problem to the equations for a self-gravitating, hydrostatically stable white dwarf, with fixed overall composition. To our knowledge, this is the first attempt to incorporate complex multinary phases into the equilibrium phase-layering diagram and mass-radius-composition dependence, both of which are reported for He-C-O and C-O-Ne white dwarfs. Finite thickness interfacial phases (“interphases”) show up at the boundaries between single-component body-centered cubic (bcc) crystalline regions, some of which have lower lattice symmetry than cubic. A second application—quasi-static settling of heavy nuclei in white dwarfs—builds on our equilibrium phase-layering method. Tests of this nonequilibrium method reveal extra phases that play the role of transient host phases for the settling species.

Thermal Neutron Imaging Using A New Pad-Based Position Sensitive Neutron Detector

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

Dioszegi I.; Vanier P.E.; Salwen C.

2016-10-29

Thermal neutrons (with mean energy of 25 meV) have a scattering mean free path of about 20 m in air. Therefore it is feasible to find localized thermal neutron sources up to ~30 m standoff distance using thermal neutron imaging. Coded aperture thermal neutron imaging was developed in our laboratory in the nineties, using He-3 filled wire chambers. Recently a new generation of coded-aperture neutron imagers has been developed. In the new design the ionization chamber has anode and cathode planes, where the anode is composed of an array of individual pads. The charge is collected on each of themore » individual 5x5 mm2 anode pads, (48x48 in total, corresponding to 24x24 cm2 sensitive area) and read out by application specific integrated circuits (ASICs). The high sensitivity of the ASICs allows unity gain operation mode. The new design has several advantages for field deployable imaging applications, compared to the previous generation of wire-grid based neutron detectors. Among these are the rugged design, lighter weight and use of non-flammable stopping gas. For standoff localization of thermalized neutron sources a low resolution (11x11 pixel) coded aperture mask has been fabricated. Using the new larger area detector and the coarse resolution mask we performed several standoff experiments using moderated californium and plutonium sources at Idaho National Laboratory. In this paper we will report on the development and performance of the new pad-based neutron camera, and present long range coded-aperture images of various thermalized neutron sources.« less

Peeling Off Neutron Skins from Neutron-Rich Nuclei: Constraints on the Symmetry Energy from Neutron-Removal Cross Sections

NASA Astrophysics Data System (ADS)

Aumann, T.; Bertulani, C. A.; Schindler, F.; Typel, S.

2017-12-01

An experimentally constrained equation of state of neutron-rich matter is fundamental for the physics of nuclei and the astrophysics of neutron stars, mergers, core-collapse supernova explosions, and the synthesis of heavy elements. To this end, we investigate the potential of constraining the density dependence of the symmetry energy close to saturation density through measurements of neutron-removal cross sections in high-energy nuclear collisions of 0.4 to 1 GeV /nucleon . We show that the sensitivity of the total neutron-removal cross section is high enough so that the required accuracy can be reached experimentally with the recent developments of new detection techniques. We quantify two crucial points to minimize the model dependence of the approach and to reach the required accuracy: the contribution to the cross section from inelastic scattering has to be measured separately in order to allow a direct comparison of experimental cross sections to theoretical cross sections based on density functional theory and eikonal theory. The accuracy of the reaction model should be investigated and quantified by the energy and target dependence of various nucleon-removal cross sections. Our calculations explore the dependence of neutron-removal cross sections on the neutron skin of medium-heavy neutron-rich nuclei, and we demonstrate that the slope parameter L of the symmetry energy could be constrained down to ±10 MeV by such a measurement, with a 2% accuracy of the measured and calculated cross sections.

High energy neutron dosimeter

DOEpatents

Rai, K.S.F.

1994-01-11

A device for measuring dose equivalents in neutron radiation fields is described. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning. 2 figures.

High energy neutron dosimeter

DOEpatents

Sun, Rai Ko S.F.

1994-01-01

A device for measuring dose equivalents in neutron radiation fields. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning.

Method and apparatus for determination of temperature, neutron absorption cross section and neutron moderating power

DOEpatents

Vagelatos, Nicholas; Steinman, Donald K.; John, Joseph; Young, Jack C.

1981-01-01

A nuclear method and apparatus determines the temperature of a medium by injecting fast neutrons into the medium and detecting returning slow neutrons in three first energy ranges by producing three respective detection signals. The detection signals are combined to produce three derived indicia each systematically related to the population of slow neutrons returning from the medium in a respective one of three second energy ranges, specifically exclusively epithermal neutrons, exclusively substantially all thermal neutrons and exclusively a portion of the thermal neutron spectrum. The derived indicia are compared with calibration indicia similarly systematically related to the population of slow neutrons in the same three second energy ranges returning from similarly irradiated calibration media for which the relationships temperature, neutron absorption cross section and neutron moderating power to such calibration indicia are known. The comparison indicates the temperature at which the calibration indicia correspond to the derived indicia and consequently the temperature of the medium. The neutron absorption cross section and moderating power of the medium can be identified at the same time.

Development of An Epi-thermal Neutron Field for Fundamental Researches for BNCT with A DT Neutron Source

NASA Astrophysics Data System (ADS)

Osawa, Yuta; Imoto, Shoichi; Kusaka, Sachie; Sato, Fuminobu; Tanoshita, Masahiro; Murata, Isao

2017-09-01

Boron Neutron Capture Therapy (BNCT) is known to be a new promising cancer therapy suppressing influence against normal cells. In Japan, Accelerator Based Neutron Sources (ABNS) are being developed for BNCT. For the spread of ABNS based BNCT, we should characterize the neutron field beforehand. For this purpose, we have been developing a low-energy neutron spectrometer based on 3He position sensitive proportional counter. In this study, a new intense epi-thermal neutron field was developed with a DT neutron source for verification of validity of the spectrometer. After the development, the neutron field characteristics were experimentally evaluated by using activation foils. As a result, we confirmed that an epi-thermal neutron field was successfully developed suppressing fast neutrons substantially. Thereafter, the neutron spectrometer was verified experimentally. In the verification, although a measured detection depth distribution agreed well with the calculated distribution by MCNP, the unfolded spectrum was significantly different from the calculated neutron spectrum due to contribution of the side neutron incidence. Therefore, we designed a new neutron collimator consisting of a polyethylene pre-collimator and boron carbide neutron absorber and confirmed numerically that it could suppress the side incident neutrons and shape the neutron flux to be like a pencil beam.

NEUTRON SHIELDING STRUCTURE

DOEpatents

Mattingly, J.T.

1962-09-25

A lightweight neutron shielding structure comprises a honeycomb core which is filled with a neutron absorbing powder. The honeycomb core is faced with parallel planar facing sheets to form a lightweight rigid unit. Suitable absorber powders are selected from among the following: B, B/sub 4/C, B/sub 2/O/ sub 3/, CaB/sub 6/, Li/sub 2/CO3, LiOH, LiBO/sub 2/, Li/s ub 2/O. The facing sheets are constructed of a neutron moderating material, so that fast neutrons will be moderated while traversing the facing sheets, and ultimately be absorbed by the absorber powder in the honeycomb. Beryllium is a preferred moderator material for use in the facing sheets. The advantage of the structure is that it combines the rigidity and light weight of a honeycomb construction with the neutron absorption properties of boron and lithium. (AEC)

Time dependent 14 MeV neutrons measurement using a polycrystalline chemical vapor deposited diamond detector at the JET tokamak

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

Angelone, M.; Pillon, M.; Bertalot, L.

A polycrystalline chemical vapor deposited (CVD) diamond detector was installed on a JET tokamak in order to monitor the time dependent 14 MeV neutron emission produced by D-T plasma pulses during the Trace Tritium Experiment (TTE) performed in October 2003. This was the first tentative ever attempted to use a CVD diamond detector as neutron monitor in a tokamak environment. Despite its small active volume, the detector was able to detect the 14 MeV neutron emission (>1.0x10{sup 15} n/shot) with good reliability and stability during the experimental campaign that lasted five weeks. The comparison with standard silicon detectors presently usedmore » at JET as 14 MeV neutron monitors is reported, showing excellent correlation between the measurements. The results prove that CVD diamond detectors can be reliably used in a tokamak environment and therefore confirm the potential of this technology for next step machines like ITER.« less

Neutron-neutron angular correlations in spontaneous fission of 252Cf and 240Pu

NASA Astrophysics Data System (ADS)

Verbeke, J. M.; Nakae, L. F.; Vogt, R.

2018-04-01

Background: Angular anisotropy has been observed between prompt neutrons emitted during the fission process. Such an anisotropy arises because the emitted neutrons are boosted along the direction of the parent fragment. Purpose: To measure the neutron-neutron angular correlations from the spontaneous fission of 252Cf and 240Pu oxide samples using a liquid scintillator array capable of pulse-shape discrimination. To compare these correlations to simulations combining the Monte Carlo radiation transport code MCNPX with the fission event generator FREYA. Method: Two different analysis methods were used to study the neutron-neutron correlations with varying energy thresholds. The first is based on setting a light output threshold while the second imposes a time-of-flight cutoff. The second method has the advantage of being truly detector independent. Results: The neutron-neutron correlation modeled by FREYA depends strongly on the sharing of the excitation energy between the two fragments. The measured asymmetry enabled us to adjust the FREYA parameter x in 240Pu, which controls the energy partition between the fragments and is so far inaccessible in other measurements. The 240Pu data in this analysis was the first available to quantify the energy partition for this isotope. The agreement between data and simulation is overall very good for 252Cf(sf ) and 240Pu(sf ) . Conclusions: The asymmetry in the measured neutron-neutron angular distributions can be predicted by FREYA. The shape of the correlation function depends on how the excitation energy is partitioned between the two fission fragments. Experimental data suggest that the lighter fragment is disproportionately excited.

Thermal neutron filter design for the neutron radiography facility at the LVR-15 reactor

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

Soltes, Jaroslav; Faculty of Nuclear Sciences and Physical Engineering, CTU in Prague,; Viererbl, Ladislav

2015-07-01

In 2011 a decision was made to build a neutron radiography facility at one of the unused horizontal channels of the LVR-15 research reactor in Rez, Czech Republic. One of the key conditions for operating an effective radiography facility is the delivery of a high intensity, homogeneous and collimated thermal neutron beam at the sample location. Additionally the intensity of fast neutrons has to be kept as low as possible as the fast neutrons may damage the detectors used for neutron imaging. As the spectrum in the empty horizontal channel roughly copies the spectrum in the reactor core, which hasmore » a high ratio of fast neutrons, neutron filter components have to be installed inside the channel in order to achieve desired beam parameters. As the channel design does not allow the instalment of complex filters and collimators, an optimal solution represent neutron filters made of large single-crystal ingots of proper material composition. Single-crystal silicon was chosen as a favorable filter material for its wide availability in sufficient dimensions. Besides its ability to reasonably lower the ratio of fast neutrons while still keeping high intensities of thermal neutrons, due to its large dimensions, it suits as a shielding against gamma radiation from the reactor core. For designing the necessary filter dimensions the Monte-Carlo MCNP transport code was used. As the code does not provide neutron cross-section libraries for thermal neutron transport through single-crystalline silicon, these had to be created by approximating the theory of thermal neutron scattering and modifying the original cross-section data which are provided with the code. Carrying out a series of calculations the filter thickness of 1 m proved good for gaining a beam with desired parameters and a low gamma background. After mounting the filter inside the channel several measurements of the neutron field were realized at the beam exit. The results have justified the expected calculated

Quasiparticle Interactions in Neutron Matter for Applications in Neutron Stars

NASA Technical Reports Server (NTRS)

Wambach, J.; Anisworth, T. L.; Pines, D.

1993-01-01

A microscopic model for the quaisiparticle interaction in neutron matter is presented. Both particle-particle (pp) and particle-hole (ph) correlation are are included. The pp correlations are treated in semi-empirical way, while ph correlations are incorporated by solving coupled two-body equations for the particle hole interaction and the scattering amplitude on the Fermi sphere. The resulting integral equations self-consistently sum the ph reducible diagrams. Antisymmetry is kept at all stages and hence the forward-scattering sum rules are obeyed. Results for Landau parameters and transport coefficients in a density regime representing the crust of a neutron star are presented. We also estimate the S-1 gap parameter for neutron superfluidity and comment briefly on neutron-star implications.

Quasiparticle Interactions in Neutron Matter for Applications in Neutron Stars

NASA Technical Reports Server (NTRS)

Wambach, J; Ainsworth, T. L.; Pines, D.

1993-01-01

A microscopic model for the quasiparticle interaction in neutron matter is presented. Both-particle (pp) and particle-hole (ph) correlations are included. The pp correlations are treated in semi-empirical way, while ph correlations are incorporated by solving coupled two-body equations for particle-hole interaction and the scattering amplitude of the Fermi sphere. The resulting integral equations self-consistently sum the ph reducible diagrams. Antisymmetry is kept at all stages and hence the forward-scattering sum rules for the scattering amplitude are obeyed. Results for Landau parameters and transport coefficients in a density regime representing the crust of a neutron star are presented. We also estimate the (1)S(sub 0) gap parameter for neutron superfluidity and comment briefly on neutron-star implications.

THERMAL NEUTRON INTENSITIES IN SOILS IRRADIATED BY FAST NEUTRONS FROM POINT SOURCES. (R825549C054)

EPA Science Inventory

Thermal-neutron fluences in soil are reported for selected fast-neutron sources, selected soil types, and selected irradiation geometries. Sources include 14 MeV neutrons from accelerators, neutrons from spontaneously fissioning ²⁵²Cf, and neutrons produced from alp...

A slow neutron polarimeter for the measurement of parity-odd neutron rotary power.

PubMed

Snow, W M; Anderson, E; Barrón-Palos, L; Bass, C D; Bass, T D; Crawford, B E; Crawford, C; Dawkins, J M; Esposito, D; Fry, J; Gardiner, H; Gan, K; Haddock, C; Heckel, B R; Holley, A T; Horton, J C; Huffer, C; Lieffers, J; Luo, D; Maldonado-Velázquez, M; Markoff, D M; Micherdzinska, A M; Mumm, H P; Nico, J S; Sarsour, M; Santra, S; Sharapov, E I; Swanson, H E; Walbridge, S B; Zhumabekova, V

2015-05-01

We present the design, description, calibration procedure, and an analysis of systematic effects for an apparatus designed to measure the rotation of the plane of polarization of a transversely polarized slow neutron beam as it passes through unpolarized matter. This device is the neutron optical equivalent of a crossed polarizer/analyzer pair familiar from light optics. This apparatus has been used to search for parity violation in the interaction of polarized slow neutrons in matter. Given the brightness of existing slow neutron sources, this apparatus is capable of measuring a neutron rotary power of dϕ/dz = 1 × 10(-7) rad/m.

First neutron generation in the BINP accelerator based neutron source.

PubMed

Bayanov, B; Burdakov, A; Chudaev, V; Ivanov, A; Konstantinov, S; Kuznetsov, A; Makarov, A; Malyshkin, G; Mekler, K; Sorokin, I; Sulyaev, Yu; Taskaev, S

2009-07-01

Pilot innovative facility for neutron capture therapy was built at Budker Institute of Nuclear Physics, Novosibirsk. This facility is based on a compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915 MeV protons bombarding a lithium target using (7)Li(p,n)(7)Be threshold reaction. The results of the first experiments on neutron generation are reported and discussed.

Radiation damage effects by electrons, protons, and neutrons in Si/Li/ detectors.

NASA Technical Reports Server (NTRS)

Liu, Y. M.; Coleman, J. A.

1972-01-01

The degradation in performance of lithium-compensated silicon nuclear particle detectors induced by irradiation at room temperature with 0.6-MeV and 1.5-MeV electrons, 1.9-MeV protons, and fast neutrons from a plutonium-beryllium source has been investigated. With increasing fluence, the irradiations produced an increase of detector leakage current, noise, capacitance, and a degradation in the performance of the detector as a charged-particle energy spectrometer. Following the irradiations, annealing effects were observed when the detectors were reverse-biased at their recommended operating voltages. Upon removal of bias, a continuous degradation of detector performance characteristics occurred. Detectors which had been damaged by electrons and protons exhibited a stabilization in their characteristics within two weeks after irradiation, whereas detectors damaged by neutrons had a continuous degradation of performance over a period of several months.

First series of total robotic hysterectomy (TRH) using new integrated table motion for the da Vinci Xi: feasibility, safety and efficacy.

PubMed

Giannini, Andrea; Russo, Eleonora; Mannella, Paolo; Palla, Giulia; Pisaneschi, Silvia; Cecchi, Elena; Maremmani, Michele; Morelli, Luca; Perutelli, Alessandra; Cela, Vito; Melfi, Franca; Simoncini, Tommaso

2017-08-01

To present the first case series of total robotic hysterectomy (TRH), using integrated table motion (ITM), which is a new feature comprising a unique operating table by Trumpf Medical that communicates wirelessly with the da Vinci Xi surgical system. ITM has been specifically developed to improve multiquadrant robotic surgery such as that conducted in colorectal surgery. Between May and October 2015, a prospective post-market study was conducted on ITM in the EU in 40 cases from different specialties. The gynecological study group comprised 12 patients. Primary endpoints were ITM feasibility, safety and efficacy. Ten patients underwent TRH. Mean number of ITM moves was three during TRH; there were 31 instances of table moves in the ten procedures. Twenty-eight of 31 ITM moves were made to gain internal exposure. The endoscope remained inserted during 29 of the 31 table movements (94%), while the instruments remained inserted during 27 of the 31 moves (87%). No external instrument collisions or other problems related to the operating table were noted. There were no ITM safety-related observations and no adverse events. This preliminary study demonstrated the feasibility, safety and efficacy of ITM for the da Vinci Xi surgical system in TRH. ITM was safe, with no adverse events related to its use. Further studies will be useful to define the real role and potential benefit of ITM in gynecological surgery.

Modulating the Neutron Flux from a Mirror Neutron Source

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

Ryutov, D D

2011-09-01

A 14-MeV neutron source based on a Gas-Dynamic Trap will provide a high flux of 14 MeV neutrons for fusion materials and sub-component testing. In addition to its main goal, the source has potential applications in condensed matter physics and biophysics. In this report, the author considers adding one more capability to the GDT-based neutron source, the modulation of the neutron flux with a desired frequency. The modulation may be an enabling tool for the assessment of the role of non-steady-state effects in fusion devices as well as for high-precision, low-signal basic science experiments favoring the use of the synchronousmore » detection technique. A conclusion is drawn that modulation frequency of up to 1 kHz and modulation amplitude of a few percent is achievable. Limitations on the amplitude of modulations at higher frequencies are discussed.« less

Prototype Stilbene Neutron Collar

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

Prasad, M. K.; Shumaker, D.; Snyderman, N.

2016-10-26

A neutron collar using stilbene organic scintillator cells for fast neutron counting is described for the assay of fresh low enriched uranium (LEU) fuel assemblies. The prototype stilbene collar has a form factor similar to standard He-3 based collars and uses an AmLi interrogation neutron source. This report describes the simulation of list mode neutron correlation data on various fuel assemblies including some with neutron absorbers (burnable Gd poisons). Calibration curves (doubles vs 235U linear mass density) are presented for both thermal and fast (with Cd lining) modes of operation. It is shown that the stilbene collar meets or exceedsmore » the current capabilities of He-3 based neutron collars. A self-consistent assay methodology, uniquely suited to the stilbene collar, using triples is described which complements traditional assay based on doubles calibration curves.« less