Energy and Mass-Number Dependence of Hadron-Nucleus Total Reaction Cross Sections

NASA Astrophysics Data System (ADS)

Kohama, Akihisa; Iida, Kei; Oyamatsu, Kazuhiro

2016-09-01

We thoroughly investigate how proton-nucleus total reaction cross sections depend on the target mass number A and the proton incident energy. In doing so, we systematically analyze nuclear reaction data that are sensitive to nuclear size, namely, proton-nucleus total reaction cross sections and differential elastic cross sections, using a phenomenological black-sphere approximation of nuclei that we are developing. In this framework, the radius of the black sphere is found to be a useful length scale that simultaneously accounts for the observed proton-nucleus total reaction cross section and first diffraction peak in the proton elastic differential cross section. This framework, which is shown here to be applicable to antiprotons, is expected to be applicable to any kind of projectile that is strongly attenuated in the nucleus. On the basis of a cross-section formula constructed within this framework, we find that a less familiar A1/6 dependence plays a crucial role in describing the energy dependence of proton-nucleus total reaction cross sections.

Low energy e-Ar momentum transfer cross-section

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

Brennan, M.J.

1992-12-01

Recent work has shown that solutions of the Boltzmann equation which use the so called {open_quotes}two-term{close_quotes} approximation provide an inadequate description of the transverse diffusion of electrons in argon gas at low values of E/N, contrary to earlier evidence. Previous determinations of the momentum transfer cross section for argon from the analysis of transport data have used two-term codes in good faith. Progress towards the determination of a new cross section in the energy range O - 4 eV, including an analysis of the energy dependence of the uncertainty in the derived cross section is reported.

Asymptotic form of the charge exchange cross section in the three body rearrangement collisions

NASA Technical Reports Server (NTRS)

Omidvar, K.

1975-01-01

A three body general rearrangement collision is considered where the initial and final bound states are described by the hydrogen-like wave functions. Mathematical models are developed to establish the relationships of quantum number, the reduced mass, and the nuclear charge of the final state. It is shown that for the low lying levels, the reciprocal of n cubed scaling law at all incident energies is only approximately satisfied. The case of the symmetric collisions is considered and it is shown that for high n and high incident energy, E, the cross section behaves as the reciprocal of E cubed. Zeros and minima in the differential cross sections in the limit of high n for protons on atomic hydrogen and positrons on atomic hydrogen are given.

Multichannel processes of H2O in the 18 eV region

NASA Technical Reports Server (NTRS)

Wu, C. Y. Robert; Judge, D. L.

1988-01-01

Measurements were made of: (1) the fluorescence cross sections of OH(A 2Sigma+) fragments; (2) the absolute cross sections producing H atoms in the n = 2, 3, and 4 states; (3) the cross section for producing excited O atoms which has an upper limit of 5 x 10 to the -21 sq cm; and (4) the fluorescence cross section for producing H2(a 3Sigma g +) fragments. It is shown that, in the 16-20 eV region, there are excellent correspondences in the peak positions and spacings among the photoabsorption, photoionization spectra, and fluorescence functions of OH(A) and H(n).

α-induced reaction cross sections in the mass range A ≈ 20 - 50: a critical review

NASA Astrophysics Data System (ADS)

Mohr, Peter

2018-01-01

In a recent review it was shown that the cross sections of α-induced reactions in the A ≈ 20 - 50 mass range follow a general and smooth trend in most cases. For comparison of cross sections of different targets at various energies the method of reduced cross sections σ red and reduced energies E red was used. Four outliers were identified: 36Ar and 40Ar with unusal small cross sections and 23Na and 33S with unusual huge cross sections. New data for 23Na were presented at this NPA-7 conference; contrary to the previous data, these new data fit into the general systematics. In addition, a relation between the most effective energy E 0 for astrophysical reaction rates (the so-called Gamow window) and the reduced energy E red is presented.

Ion charge state distribution effects on elastic X-ray Thomson scattering

NASA Astrophysics Data System (ADS)

Iglesias, Carlos A.

2018-03-01

Analytic models commonly applied in elastic X-ray Thomson scattering cross-section calculations are used to generate results from a discrete ion charge distribution and an average charge description. Comparisons show that interchanging the order of the averaging procedure can appreciably alter the cross-section, especially for plasmas with partially filled K-shell bound electrons. In addition, two common approximations to describe the free electron density around an ion are shown to yield significantly different elastic X-ray Thomson scattering cross-sections.

Quantum tunneling resonant electron transfer process in Lorentzian plasmas

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

Hong, Woo-Pyo; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 426-791

The quantum tunneling resonant electron transfer process between a positive ion and a neutral atom collision is investigated in nonthermal generalized Lorentzian plasmas. The result shows that the nonthermal effect enhances the resonant electron transfer cross section in Lorentzian plasmas. It is found that the nonthermal effect on the classical resonant electron transfer cross section is more significant than that on the quantum tunneling resonant charge transfer cross section. It is shown that the nonthermal effect on the resonant electron transfer cross section decreases with an increase of the Debye length. In addition, the nonthermal effect on the quantum tunnelingmore » resonant electron transfer cross section decreases with increasing collision energy. The variation of nonthermal and plasma shielding effects on the quantum tunneling resonant electron transfer process is also discussed.« less

Upper-limit charge exchange cross sections for mercury (plus) on molybdenum and cesium (plus) on aluminum

NASA Technical Reports Server (NTRS)

Dugan, J. V., Jr.

1972-01-01

Upper-limit charge exchange cross sections are calculated for Hg(+) on Mo and Cs(+) on Al. The cross sections are calculated from the polarization interaction at low ion energies (1 to 500 eV) and by assuming favorable curve crossings with a hard-core reaction radius at higher energies (500 eV to 10 keV). The cross sections for Hg(+) on Mo becomes greater than corresponding Hg Hg(+) resonance values at ion energies below 2 eV, whereas the Cs(+) Al values remain considerably lower than the Cs(+)Cs resonance value at all ion energies. It is also shown that charge exchange of slow Hg(+) with Mo may be important for spacecraft with electron bombardment thrusters.

Effect of phase and orbital wave parameter choices on CS and IOS degeneracy averaged differential cross sections

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

Khare, V.; Fitz, D.E.; Kouri, D.J.

1980-09-15

The effect of phase choice and partial wave parameter choice on CS and IOS inelastic degeneracy averaged differential cross sections is studied. An approximate simplified CS scattering amplitude for l-bar=1/2(l'+l) is derived and is shown to have a form which closely resembles the McGuire--Kouri scattering amplitude for odd ..delta..j transitions and reduces to it for even ..delta..j transitions. The choice of phase in the CS wave function is shown to result in different approximations which yield significantly different shapes for the degeneracy averaged differential cross section. Time reversal symmetry arguments are employed to select the proper phase choice. IOS calculationsmore » of the degeneracy averaged differential cross sections of He--CO, He--Cl and Ne--HD using l-bar=1/2(l+l') and the phase choice which ensures proper time reversal symmetry are found to correct the phase disagreement which was previously noted for odd ..delta..j transitions using l-bar=l or l' and either the time reversal phase or other phase choices.« less

Closed-form expressions for state-to-state charge-transfer differential cross sections in a modified Faddeev three-body approach

NASA Astrophysics Data System (ADS)

Adivi, E. Ghanbari; Brunger, M. J.; Bolorizadeh, M. A.; Campbell, L.

2007-02-01

The second-order Faddeev-Watson-Lovelace approximation in a modified form is applied to charge transfer from hydrogenlike target atoms by a fully stripped energetic projectile ion. The state-to-state, nlm→n'l'm' , partial transition amplitudes are calculated analytically. The method is specifically applied to the collision of protons with hydrogen atoms, where differential cross sections of different transitions are calculated for incident energies of 2.8 and 5.0MeV . It is shown that the Thomas peak is present in all transition cross sections. The partial cross sections are then summed and compared with the available forward-angle experimental data, showing good agreement.

Thresholds and the rising pion inclusive cross section

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

Jones, S.T.

In the context of the hypothesis of the Pomeron-f identity, it is shown that the rising pion inclusive cross section can be explained over a wide range of energies as a series of threshold effects. Low-mass thresholds are seen to be important. In order to understand the contributions of high-mass thresholds (flavoring), a simple two-channel multiperipheral model is examined. The analysis sheds light on the relation between thresholds and Mueller-Regge couplings. In particular, it is seen that inclusive-, and total-cross-section threshold mechanisms may differ. A quantitative model based on this idea and utilizing previous total-cross-section fits is seen to agreemore » well with experiment.« less

Photoabsorption cross section of acetylene in the EUV region

NASA Technical Reports Server (NTRS)

Wu, C. Y. R.; Judge, D. L.

1985-01-01

The measurement of the absolute photoabsorption cross sections of C2H2 in the 175-740 A region by means of a double ionization chamber is reported. The continuum background source is the synchrotron radiation emitted by the Wisconsin 240 MeV electron storage ring. It is found that the cross sections range from 2 to a maximum of 36 Mb. Two new Rydberg series are identified and the cross section data are applied in the analysis of various sum rules. From the rules, it is shown that the data of C2H2 in the 580-1088 A range may be too low, while the measured ionization transition moment may be too high.

The radar cross section of dielectric disks

NASA Technical Reports Server (NTRS)

Levine, D. M.

1982-01-01

A solution is presented for the backscatter (nonstatic) radar cross section of dielectric disks of arbitrary shape, thickness and dielectric constant. The result is obtained by employing a Kirchhoff type approximation to obtain the fields inside the disk. The internal fields induce polarization and conduction currents from which the scattered fields and the radar cross section can be computed. The solution for the radar cross section obtained in this manner is shown to agree with known results in the special cases of normal incidence, thin disks and perfect conductivity. The solution can also be written as a product of the reflection coefficient of an identically oriented slab times the physical optics solution for the backscatter cross section of a perfectly conducting disk of the same shape. This result follows directly from the Kirchhoff type approximation without additional assumptions.

Geodesic acoustic modes in noncircular cross section tokamaks

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

Sorokina, E. A., E-mail: sorokina.ekaterina@gmail.com; Lakhin, V. P.; Konovaltseva, L. V.

2017-03-15

The influence of the shape of the plasma cross section on the continuous spectrum of geodesic acoustic modes (GAMs) in a tokamak is analyzed in the framework of the MHD model. An expression for the frequency of a local GAM for a model noncircular cross section plasma equilibrium is derived. Amendments to the oscillation frequency due to the plasma elongation and triangularity and finite tokamak aspect ratio are calculated. It is shown that the main factor affecting the GAM spectrum is the plasma elongation, resulting in a significant decrease in the mode frequency.

Geologic cross sections and preliminary geologic map of the Questa Area, Taos County, New Mexico

USGS Publications Warehouse

Bauer, Paul W.; Grauch, V.J.S.; Johnson, Peggy S.; Thompson, Ren A.; Drenth, Benjamin J.; Kelson, Keith I.

2015-01-01

In 2011, the senior authors were contacted by Ron Gardiner of Questa, and Village of Questa Mayor Esther Garcia, to discuss the existing and future groundwater supply for the Village of Questa. This meeting led to the development of a plan in 2013 to perform an integrated geologic, geophysical, and hydrogeologic investigation of the Questa area by the New Mexico Bureau of Geology & Mineral Resources (NMBG), the U.S. Geological Survey (USGS), and New Mexico Tech (NMT). The NMBG was responsible for the geologic map and geologic cross sections. The USGS was responsible for a detailed geophysical model to be incorporated into the NMBG products. NMT was responsible for providing a graduate student to develop a geochemical and groundwater flow model. This report represents the final products of the geologic and geophysical investigations conducted by the NMBG and USGS. The USGS final products have been incorporated directly into the geologic cross sections. The objective of the study was to characterize and interpret the shallow (to a depth of approximately 5,000 ft) three-dimensional geology and preliminary hydrogeology of the Questa area. The focus of this report is to compile existing geologic and geophysical data, integrate new geophysical data, and interpret these data to construct three, detailed geologic cross sections across the Questa area. These cross sections can be used by the Village of Questa to make decisions about municipal water-well development, and can be used in the future to help in the development of a conceptual model of groundwater flow for the Questa area. Attached to this report are a location map, a preliminary geologic map and unit descriptions, tables of water wells and springs used in the study, and three detailed hydrogeologic cross sections shown at two different vertical scales. The locations of the cross sections are shown on the index map of the cross section sheet.

How to Use Benchmark and Cross-section Studies to Improve Data Libraries and Models

NASA Astrophysics Data System (ADS)

Wagner, V.; Suchopár, M.; Vrzalová, J.; Chudoba, P.; Svoboda, O.; Tichý, P.; Krása, A.; Majerle, M.; Kugler, A.; Adam, J.; Baldin, A.; Furman, W.; Kadykov, M.; Solnyshkin, A.; Tsoupko-Sitnikov, S.; Tyutyunikov, S.; Vladimirovna, N.; Závorka, L.

2016-06-01

Improvements of the Monte Carlo transport codes and cross-section libraries are very important steps towards usage of the accelerator-driven transmutation systems. We have conducted a lot of benchmark experiments with different set-ups consisting of lead, natural uranium and moderator irradiated by relativistic protons and deuterons within framework of the collaboration “Energy and Transmutation of Radioactive Waste”. Unfortunately, the knowledge of the total or partial cross-sections of important reactions is insufficient. Due to this reason we have started extensive studies of different reaction cross-sections. We measure cross-sections of important neutron reactions by means of the quasi-monoenergetic neutron sources based on the cyclotrons at Nuclear Physics Institute in Řež and at The Svedberg Laboratory in Uppsala. Measurements of partial cross-sections of relativistic deuteron reactions were the second direction of our studies. The new results obtained during last years will be shown. Possible use of these data for improvement of libraries, models and benchmark studies will be discussed.

Status of the R-matrix Code AMUR toward a consistent cross-section evaluation and covariance analysis for the light nuclei

NASA Astrophysics Data System (ADS)

Kunieda, Satoshi

2017-09-01

We report the status of the R-matrix code AMUR toward consistent cross-section evaluation and covariance analysis for the light-mass nuclei. The applicable limit of the code is extended by including computational capability for the charged-particle elastic scattering cross-sections and the neutron capture cross-sections as example results are shown in the main texts. A simultaneous analysis is performed on the 17O compound system including the 16O(n,tot) and 13C(α,n)16O reactions together with the 16O(n,n) and 13C(α,α) scattering cross-sections. It is found that a large theoretical background is required for each reaction process to obtain a simultaneous fit with all the experimental cross-sections we analyzed. Also, the hard-sphere radii should be assumed to be different from the channel radii. Although these are technical approaches, we could learn roles and sources of the theoretical background in the standard R-matrix.

In-plane stability analysis of non-uniform cross-sectioned curved beams

NASA Astrophysics Data System (ADS)

Öztürk, Hasan; Yeşilyurt, İsa; Sabuncu, Mustafa

2006-09-01

In this study, in-plane stability analysis of non-uniform cross-sectioned thin curved beams under uniformly distributed dynamic loads is investigated by using the Finite Element Method. The first and second unstable regions are examined for dynamic stability. In-plane vibration and in-plane buckling are also studied. Two different finite element models, representing variations of cross-section, are developed by using simple strain functions in the analysis. The results obtained from this study are compared with the results of other investigators in existing literature for the fundamental natural frequency and critical buckling load. The effects of opening angle, variations of cross-section, static and dynamic load parameters on the stability regions are shown in graphics.

Thickness dependence of scattering cross-sections in quantitative scanning transmission electron microscopy.

PubMed

Martinez, G T; van den Bos, K H W; Alania, M; Nellist, P D; Van Aert, S

2018-04-01

In quantitative scanning transmission electron microscopy (STEM), scattering cross-sections have been shown to be very sensitive to the number of atoms in a column and its composition. They correspond to the integrated intensity over the atomic column and they outperform other measures. As compared to atomic column peak intensities, which saturate at a given thickness, scattering cross-sections increase monotonically. A study of the electron wave propagation is presented to explain the sensitivity of the scattering cross-sections. Based on the multislice algorithm, we analyse the wave propagation inside the crystal and its link to the scattered signal for the different probe positions contained in the scattering cross-section for detector collection in the low-, middle- and high-angle regimes. The influence to the signal from scattering of neighbouring columns is also discussed. Copyright © 2018 Elsevier B.V. All rights reserved.

Characteristics of Polarisation in the Ramsauer-Townsend Minima in Strongly Coupled Semiclassic Plasmas

NASA Astrophysics Data System (ADS)

Lee, Myoung-Jae; Jung, Young-Dae

2017-10-01

The influence of quantum shielding on the Ramsauer-Townsend phenomena for the total electron-atom polarisation collision cross-section is investigated in partially ionised strongly coupled semiclassic plasmas. The result shows that the quantum shielding effect changes the position of the Ramsauer energy in partially ionised strongly coupled plasmas. It is also found that the quantum shielding effect enhances the total electron-atom collision cross-section when the collision energy is greater than the Ramsauer energy; however, it suppresses the collision cross-section when the collision energy is smaller than the Ramsauer energy. In addition, it is shown that the plasma screening effect significantly changes the position of the Ramsauer energy and the influence of plasma screening on the magnitude of the collision cross-section is more significant near the Ramsauer energy domain. The variations of the Ramsauer energy and the collision cross-section due to the quantum shielding effect are also discussed.

Neutron Fission of 235,237,239U and 241,243Pu: Cross Sections, Integral Cross Sections and Cross Sections on Excited States

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

Younes, W; Britt, H C

In a recent paper submitted to Phys. Rev. C they have presented estimates for (n,f) cross sections on a series of Thorium, Uranium and Plutonium isotopes over the range E{sub n} = 0.1-2.5 MeV. The (n,f) cross sections for many of these isotopes are difficult or impossible to measure in the laboratory. The cross sections were obtained from previous (t,pf) reaction data invoking a model which takes into account the differences between (t,pf) and (n,f) reaction processes, and which includes improved estimates for the neutron compound formation process. The purpose of this note is: (1) to compare the estimated crossmore » sections to current data files in both ENDF and ENDL databases; (2) to estimate ratios of cross sections relatively to {sup 235}U integrated over the ''tamped flattop'' critical assembly spectrum that was used in the earlier {sup 237}U report; and (3) to show the effect on the integral cross sections when the neutron capturing state is an excited rotational state or an isomer. The isomer and excited state results are shown for {sup 235}U and {sup 237}U.« less

Theoretical studies of dissociative recombination

NASA Technical Reports Server (NTRS)

Guberman, S. L.

1985-01-01

The calculation of dissociative recombination rates and cross sections over a wide temperature range by theoretical quantum chemical techniques is described. Model calculations on electron capture by diatomic ions are reported which illustrate the dependence of the rates and cross sections on electron energy, electron temperature, and vibrational temperature for three model crossings of neutral and ionic potential curves. It is shown that cross sections for recombination to the lowest vibrational level of the ion can vary by several orders of magnitude depending upon the position of the neutral and ionic potential curve crossing within the turning points of the v = 1 vibrational level. A new approach for calculating electron capture widths is reported. Ab initio calculations are described for recombination of O2(+) leading to excited O atoms.

Measurement of sigma(e+e- -->psi(3770)-->hadrons) at Ec.m.=3773 MeV.

PubMed

Besson, D; Pedlar, T K; Cronin-Hennessy, D; Gao, K Y; Gong, D T; Hietala, J; Kubota, Y; Klein, T; Lang, B W; Poling, R; Scott, A W; Smith, A; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A; Zweber, P; Ernst, J; Arms, K; Severini, H; Dytman, S A; Love, W; Mehrabyan, S; Mueller, J A; Savinov, V; Li, Z; Lopez, A; Mendez, H; Ramirez, J; Huang, G S; Miller, D H; Pavlunin, V; Sanghi, B; Shipsey, I P J; Adams, G S; Anderson, M; Cummings, J P; Danko, I; Napolitano, J; He, Q; Muramatsu, H; Park, C S; Thorndike, E H; Coan, T E; Gao, Y S; Liu, F; Artuso, M; Boulahouache, C; Blusk, S; Butt, J; Li, J; Menaa, N; Mountain, R; Nisar, S; Randrianarivony, K; Redjimi, R; Sia, R; Skwarnicki, T; Stone, S; Wang, J C; Zhang, K; Csorna, S E; Bonvicini, G; Cinabro, D; Dubrovin, M; Lincoln, A; Briere, R A; Chen, G P; Chen, J; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Rosner, J L; Adam, N E; Alexander, J P; Berkelman, K; Cassel, D G; Duboscq, J E; Ecklund, K M; Ehrlich, R; Fields, L; Gibbons, L; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Jones, C D; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Mahlke-Krüger, H; Meyer, T O; Onyisi, P U E; Patterson, J R; Peterson, D; Phillips, E A; Pivarski, J; Riley, D; Ryd, A; Sadoff, A J; Schwarthoff, H; Shi, X; Stroiney, S; Sun, W M; Wilksen, T; Weinberger, M; Athar, S B; Avery, P; Breva-Newell, L; Patel, R; Potlia, V; Stoeck, H; Yelton, J; Rubin, P; Cawlfield, C; Eisenstein, B I; Karliner, I; Kim, D; Lowrey, N; Naik, P; Sedlack, C; Selen, M; White, E J; Wiss, J; Shepherd, M R; Asner, D M; Edwards, K W

2006-03-10

We measure the cross section for e+e- -->psi(3770) -->hadrons at Ec.m.=3773 MeV to be (6.38+/-0.08(+0.41)(-0.30) nb using the CLEO detector at the CESR e+e- collider. The difference between this and the e+e- -->psi(3770) -->DD cross section at the same energy is found to be (-0.01+/-0.08(+0.41)(-0.30) nb. With the observed total cross section, we extract Gamma(ee)(psi(3770))=(0.204+/-0.003(+0.041)(-0.027) keV. Uncertainties shown are statistical and systematic, respectively.

Sonographic evaluation of the greater occipital nerve in unilateral occipital neuralgia.

PubMed

Cho, John Chin-Suk; Haun, Daniel W; Kettner, Norman W

2012-01-01

Occipital neuralgia is a headache that may result from greater occipital nerve entrapment. Entrapped peripheral nerves typically have an increase in cross-sectional area. The purpose of this study was to measure the cross-sectional area and circumference of symptomatic and asymptomatic greater occipital nerves in patients with unilateral occipital neuralgia and to correlate the greater occipital nerve cross-sectional area with headache severity, sex, and body mass index. Both symptomatic and contralateral asymptomatic greater occipital nerve cross-sectional areas and circumferences were measured by a single examiner using sonography in 17 patients. The Wilcoxon signed rank test and Spearman rank order correlation coefficient were used to analyze the data. Significant differences between the cross-sectional areas and circumferences of the symptomatic and asymptomatic greater occipital nerves were noted (P < .001). No difference existed in cross-sectional area (P = .40) or circumference (P = .10) measurements of the nerves between male and female patients. A significant correlation existed between the body mass index and symptomatic (r = 0.424; P = .045) and asymptomatic (r = 0.443; P = .037) cross-sectional areas. There was no correlation shown between the cross-sectional area of the symptomatic nerve and the severity of Headache Impact Test 6 scores (r = -0.342; P = .179). We report sonographic evidence showing an increased cross-sectional area and circumference of the symptomatic greater occipital nerve in patients with unilateral occipital neuralgia.

Generalization of the optical theorem for an arbitrary multipole in the presence of a transparent half-space

NASA Astrophysics Data System (ADS)

Eremin, Yu. A.; Sveshnikov, A. G.

2017-07-01

The optical theorem is generalized to the case of excitation of a local inhomogeneity introduced in a transparent substrate by a multipole of arbitrary order. It is shown that, to calculate the generalized extinction cross section, it is sufficient to calculate the derivatives of the scattered field at a single point by adding a constant and a definite integral. Apart from general scientific interest, the proposed generalization makes it possible to calculate the absorption cross section by subtracting the scattering cross section from the extinction cross section. The latter fact is important, because the scattered field in the far zone contains no Sommerfeld integrals. In addition, the proposed generalization allows one to test computer modules for the case where a lossless inhomogeneity is considered.

Design and Fabrication of Submicron Magnetic Bubble Device Technology.

DTIC Science & Technology

1986-10-31

interface LPE bubble film GGG substrate Figure 2: Cross section of a silicon on garnet magnetodiode. I : R R R/ B>O0 B 0 z V............. ... ..AV dummy...Carnegie Mellon University, Pittsburgh, Pa 15213. Section I Introduction The main thrust of our LPE garnet film growth program is to develop> films ...shown in Table I and the best choice for an isotropic magnetostrictive film is shown by an asterik. Section IM LPE Film Growth Technique All garnet

A search for the production of direct leptons in nucleon-nucleus and nucleus-nucleus collisions. [Intermediate Energy Nuclear Physics Group, Dept. of Physics and Astronomy, Louisiana State Univ. , Baton Rouge

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

Kirk, P.N.

1992-12-15

Activities included contributions to the AMY Collaboration, the transverse energy detector, the Di-Lepton Spectrometer, with emphasis on the single-lepton experiment. Elastic and inelastic scattering differential cross sections and total cross sections are shown for [pi][sup +] and [pi][sup [minus

Photoionization research on atomic radiation. 3: The ionization cross section of atomic nitrogen

NASA Technical Reports Server (NTRS)

Comes, F. J.; Elzer, A.

1982-01-01

The photoionization cross section of atomic nitrogen was measured between the ionization limit and 432 A. The experimental values are well fitted by those from a calculation of HENRY due to the dipole velocity approximation. A Rydberg series converging to the 5S-state of the ion is clearly identified from the ionization measurements and is shown to ionize.

About creation of machines for rock destruction with formation of apertures of various cross-sections

NASA Astrophysics Data System (ADS)

Zhukov, I. A.; Dvornikov, L. T.; Nikitenko, S. M.

2016-04-01

The article presents the results of the experimental research of the high strength rock destruction by a bladeless tool. Rational circuit designs of disposing of indenters in the impact part of the drill bits and a diamond tool are justified. New constructive solutions of reinforcing bladeless drill bits, which allow drilling blast-holes of the various cross-section, are shown.

Total absorption and photoionization cross sections of water vapor between 100 and 1000 A

NASA Technical Reports Server (NTRS)

Haddad, G. N.; Samson, J. A. R.

1986-01-01

Absolute photoabsorption and photoionization cross sections of water vapor are reported at a large number of discrete wavelengths between 100 and 1000 A with an estimate error of + or - 3 percent in regions free from any discrete structure. The double ionization chamber technique utilized is described. Recent calculations are shown to be in reasonable agreement with the present data.

Effect of core polarizability on photoionization cross-section calculations.

NASA Technical Reports Server (NTRS)

Kirkpatrick, R. C.

1972-01-01

Demonstration of the importance of core polarizability in a case where cancellation is only moderate, with suggestion of an improvement to the scaled Thomas-Fermi (STF) wave functions of Stewart and Rotenberg (1965). The inclusion of dipole polarizability of the core for argon is shown to substantially improve the agreement between the theoretical and experimental photoionization cross sections for the ground-state configuration.

Bistatic radar cross section of a perfectly conducting rhombus-shaped flat plate

NASA Astrophysics Data System (ADS)

Fenn, Alan J.

1990-05-01

The bistatic radar cross section of a perfectly conducting flat plate that has a rhombus shape (equilateral parallelogram) is investigated. The Ohio State University electromagnetic surface patch code (ESP version 4) is used to compute the theoretical bistatic radar cross section of a 35- x 27-in rhombus plate at 1.3 GHz over the bistatic angles 15 deg to 142 deg. The ESP-4 computer code is a method of moments FORTRAN-77 program which can analyze general configurations of plates and wires. This code has been installed and modified at Lincoln Laboratory on a SUN 3 computer network. Details of the code modifications are described. Comparisons of the method of moments simulations and measurements of the rhombus plate are made. It is shown that the ESP-4 computer code provides a high degree of accuracy in the calculation of copolarized and cross-polarized bistatic radar cross section patterns.

Statistical investigation of avalanches of three-dimensional small-world networks and their boundary and bulk cross-sections

NASA Astrophysics Data System (ADS)

Najafi, M. N.; Dashti-Naserabadi, H.

2018-03-01

In many situations we are interested in the propagation of energy in some portions of a three-dimensional system with dilute long-range links. In this paper, a sandpile model is defined on the three-dimensional small-world network with real dissipative boundaries and the energy propagation is studied in three dimensions as well as the two-dimensional cross-sections. Two types of cross-sections are defined in the system, one in the bulk and another in the system boundary. The motivation of this is to make clear how the statistics of the avalanches in the bulk cross-section tend to the statistics of the dissipative avalanches, defined in the boundaries as the concentration of long-range links (α ) increases. This trend is numerically shown to be a power law in a manner described in the paper. Two regimes of α are considered in this work. For sufficiently small α s the dominant behavior of the system is just like that of the regular BTW, whereas for the intermediate values the behavior is nontrivial with some exponents that are reported in the paper. It is shown that the spatial extent up to which the statistics is similar to the regular BTW model scales with α just like the dissipative BTW model with the dissipation factor (mass in the corresponding ghost model) m2˜α for the three-dimensional system as well as its two-dimensional cross-sections.

Reducing Uncertainties in Neutron-Induced Fission Cross Sections Using a Time Projection Chamber

NASA Astrophysics Data System (ADS)

Manning, Brett; Niffte Collaboration

2015-10-01

Neutron-induced fission cross sections for actinides have long been of great interest for nuclear energy and stockpile stewardship. Traditionally, measurements were performed using fission chambers which provided limited information about the detected fission events. For the case of 239Pu(n,f), sensitivity studies have shown a need for more precise measurements. Recently the Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) has developed the fission Time Projection Chamber (fissionTPC) to measure fission cross sections to better than 1% uncertainty by providing 3D tracking of fission fragments. The fissionTPC collected data to calculate the 239Pu(n,f) cross section at the Weapons Neutron Research facility at the Los Alamos Neutron Science Center during the 2014 run cycle. Preliminary analysis has been focused on studying particle identification and target and beam non-uniformities to reduce the uncertainty on the cross section. Additionally, the collaboration is investigating other systematic errors that could not be well studied with a traditional fission chamber. LA-UR-15-24906.

Influence of quantum diffraction and shielding on electron-ion collision in two-component semiclassical plasmas

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

Hong, Woo-Pyo; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 426-791

2015-01-15

The influence of quantum diffraction and shielding on the electron-ion collision process is investigated in two-component semiclassical plasmas. The eikonal method and micropotential taking into account the quantum diffraction and shielding are used to obtain the eikonal scattering phase shift and the eikonal collision cross section as functions of the collision energy, density parameter, Debye length, electron de Broglie wavelength, and the impact parameter. The result shows that the quantum diffraction and shielding effects suppress the eikonal scattering phase shift as well as the differential eikonal collision cross section, especially, in small-impact parameter regions. It is also shown that themore » quantum shielding effect on the eikonal collision cross section is more important in low-collision energies. In addition, it is found that the eikonal collision cross section increases with an increase in the density parameter. The variations of the eikonal cross section due to the quantum diffraction and shielding effects are also discussed.« less

A new self-shielding method based on a detailed cross-section representation in the resolved energy domain

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

Saygin, H.; Hebert, A.

The calculation of a dilution cross section {bar {sigma}}{sub e} is the most important step in the self-shielding formalism based on the equivalence principle. If a dilution cross section that accurately characterizes the physical situation can be calculated, it can then be used for calculating the effective resonance integrals and obtaining accurate self-shielded cross sections. A new technique for the calculation of equivalent cross sections based on the formalism of Riemann integration in the resolved energy domain is proposed. This new method is compared to the generalized Stamm`ler method, which is also based on an equivalence principle, for a two-regionmore » cylindrical cell and for a small pressurized water reactor assembly in two dimensions. The accuracy of each computing approach is obtained using reference results obtained from a fine-group slowing-down code named CESCOL. It is shown that the proposed method leads to slightly better performance than the generalized Stamm`ler approach.« less

Improvement of one-nucleon removal and total reaction cross sections in the Liège intranuclear-cascade model using Hartree-Fock-Bogoliubov calculations

NASA Astrophysics Data System (ADS)

Rodríguez-Sánchez, Jose Luis; David, Jean-Christophe; Mancusi, Davide; Boudard, Alain; Cugnon, Joseph; Leray, Sylvie

2017-11-01

The prediction of one-nucleon-removal cross sections by the Liège intranuclear-cascade model has been improved using a refined description of the matter and energy densities in the nuclear surface. Hartree-Fock-Bogoliubov calculations with the Skyrme interaction are used to obtain a more realistic description of the radial-density distributions of protons and neutrons, as well as the excitation-energy uncorrelation at the nuclear surface due to quantum effects and short-range correlations. The results are compared with experimental data covering a large range of nuclei, from carbon to uranium, and projectile kinetic energies. We find that the new approach is in good agreement with experimental data of one-nucleon-removal cross sections covering a broad range in nuclei and energies. The new ingredients also improve the description of total reaction cross sections induced by protons at low energies, the production cross sections of heaviest residues close to the projectile, and the triple-differential cross sections for one-proton removal. However, other observables such as quadruple-differential cross sections of coincident protons do not present any sizable sensitivity to the new approach. Finally, the model is also tested for light-ion-induced reactions. It is shown that the new parameters can give a reasonable description of the nucleus-nucleus total reaction cross sections at high energies.

Neutron-induced fission cross section of 242Pu from 15 MeV to 20 MeV

NASA Astrophysics Data System (ADS)

Jovančević, N.; Salvador-Castineira, P.; Daraban, L.; Vidali, M.; Heyse, J.; Oberstedt, S.; Hambsch, F.-J.; Bonaldi, C.; Geerts, W.

2017-09-01

Accurate nuclear-data needs in the fast-neutron-energy region have been recently addressed for the development of next generation nuclear power plants (GEN-IV) by the OECD Nuclear Energy Agency (NEA). This sensitivity study has shown that of particular interest is the 242Pu(n,f) cross section for fast reactor systems. Measurements have been performed with quasi-monoenergetic neutrons in the energy range from 15 MeV to 20 MeV produced by the Van de Graaff accelerator of the JRC-Geel. A twin Frisch-grid ionization chamber has been used in a back-to-back configuration as fission fragment detector. The 242Pu(n,f) cross section has been normalized to 238U(n,f) cross section data. The results were compared with existing literature data and show acceptable agreement within 5%.

Accurate Cross Sections for Microanalysis.

PubMed

Rez, Peter

2002-01-01

To calculate the intensity of x-ray emission in electron beam microanalysis requires a knowledge of the energy distribution of the electrons in the solid, the energy variation of the ionization cross section of the relevant subshell, the fraction of ionizations events producing x rays of interest and the absorption coefficient of the x rays on the path to the detector. The theoretical predictions and experimental data available for ionization cross sections are limited mainly to K shells of a few elements. Results of systematic plane wave Born approximation calculations with exchange for K, L, and M shell ionization cross sections over the range of electron energies used in microanalysis are presented. Comparisons are made with experimental measurement for selected K shells and it is shown that the plane wave theory is not appropriate for overvoltages less than 2.5 V.

Relativistic three-dimensional Lippmann-Schwinger cross sections for space radiation applications

NASA Astrophysics Data System (ADS)

Werneth, C. M.; Xu, X.; Norman, R. B.; Maung, K. M.

2017-12-01

Radiation transport codes require accurate nuclear cross sections to compute particle fluences inside shielding materials. The Tripathi semi-empirical reaction cross section, which includes over 60 parameters tuned to nucleon-nucleus (NA) and nucleus-nucleus (AA) data, has been used in many of the world's best-known transport codes. Although this parameterization fits well to reaction cross section data, the predictive capability of any parameterization is questionable when it is used beyond the range of the data to which it was tuned. Using uncertainty analysis, it is shown that a relativistic three-dimensional Lippmann-Schwinger (LS3D) equation model based on Multiple Scattering Theory (MST) that uses 5 parameterizations-3 fundamental parameterizations to nucleon-nucleon (NN) data and 2 nuclear charge density parameterizations-predicts NA and AA reaction cross sections as well as the Tripathi cross section parameterization for reactions in which the kinetic energy of the projectile in the laboratory frame (TLab) is greater than 220 MeV/n. The relativistic LS3D model has the additional advantage of being able to predict highly accurate total and elastic cross sections. Consequently, it is recommended that the relativistic LS3D model be used for space radiation applications in which TLab > 220MeV /n .

Comparison of local exchange potentials of electron-N2 scattering

NASA Astrophysics Data System (ADS)

Rumble, J. R., Jr.; Truhlar, D. G.

1980-05-01

Vibrationally and electronically elastic electron scattering by N2 at 2-30 eV impact energy is considered. Static, static-exchange, and static-exchange-plus-polarization potentials, Cade-Sales-Wahl and INDO/1s wave functions, and semiclassical exchange and Hara free-electron-gas exchange potentials are examined. It is shown that the semiclassical exchange approximation is too attractive at low energy for N2. It is also shown quantitatively by consideration of partial and total integral cross sections how the effects of approximations to exchange become smaller as the incident energy is increased until the differences are about 8% for the total integral cross section at 30 eV.

Justification of the Shape of a Non-Circular Cross-Section for Drilling With a Roller Cutter

NASA Astrophysics Data System (ADS)

Buyalich, Gennady; Husnutdinov, Mikhail

2017-11-01

The parameters of the shape of non-circular cross-section affect not only the process of blasting, but also the design of the tool and the process of drilling as well. In the conditions of open-pit mining, it is reasonable to use a roller cutter to produce a non-circular cross-section of blasting holes. With regard to the roller cutter, the impact of the cross-section shape on the oscillations of the axial force arising upon its rotation is determined. It is determined that a polygonal shape with rounded comers of the borehole walls connections and their convex shape, which ensures a smaller range of the total axial force and the torque deflecting the bit from the axis of its rotation is the rational form of the non-circular cross-section of the borehole in terms of bit design. It has been shown that the ratio of the number of cutters to the number of borehole corners must be taken into account when justifying the shape of the cross-section, both from the point of view of the effectiveness of the explosion action and from the point of view of the rational design of the bit.

Energy conservation - A test for scattering approximations

NASA Technical Reports Server (NTRS)

Acquista, C.; Holland, A. C.

1980-01-01

The roles of the extinction theorem and energy conservation in obtaining the scattering and absorption cross sections for several light scattering approximations are explored. It is shown that the Rayleigh, Rayleigh-Gans, anomalous diffraction, geometrical optics, and Shifrin approximations all lead to reasonable values of the cross sections, while the modified Mie approximation does not. Further examination of the modified Mie approximation for the ensembles of nonspherical particles reveals additional problems with that method.

Stratigraphic cross section of measured sections and drill holes of the Neslan Formation and adjacent formations, Book Cliffs Area, Colorado and Utah

USGS Publications Warehouse

Kirshbaum, Mark A.; Spear, Brianne D.

2012-01-01

This study updates a stratigraphic cross section published as plate 2 in Kirschbaum and Hettinger (2004) Digital Data Series 69-G (http://pubs.usgs.gov/dds/dds-069/dds-069-g/). The datum is a marine/tidal ravinement surface within the Cozzette Sandstone Member of the Iles Formation and the Thompson Canyon Sandstone and Sulphur Canyon Sandstone Beds of the Neslen Formation. One of the cores shown was included on the original cross section, and new core descriptions have been added to the upper part of the cored interval. A new core description (S178) is included in this report. Cores are stored in the U.S. Geological Survey Core Research Facility at the Denver Federal Center, Colorado. The following information has also been added to help define the stratigraphic framework: 1) At least five claystones interpreted as altered volcanic ashes have been identified and may give future workers a correlation tool within the largely continental section. 2) Thickness and general geometry of the Sego Sandstone, Buck Tongue of the Mancos Shale, and Castlegate Sandstone have been added to provide additional stratigraphic context. 3) The geometry in the Sego Sandstone, Buck Tongue of the Mancos Shale, and Castlegate Sandstone has been added to provide additional stratigraphic context. 4) Ammonite collections are from Gill and Hail. The zone of Didymoceras nebrascense projected into the East Salt Wash area is based on correlation of the flooding surface at the base of the Cozzette Member to this point as shown in Kirschbaum and Hettinger. 5) A leaf locality of the Denver Museum of Nature and Science is shown in its approximate stratigraphic position near Thompson Canyon. 6) A dinosaur locality of the Natural History Museum of Utah is shown in the Horse Canyon area measured section at the stratigraphic position where it was extracted.

Measurement of e+e-→K K ¯J /ψ cross sections at center-of-mass energies from 4.189 to 4.600 GeV

NASA Astrophysics Data System (ADS)

Ablikim, M.; Achasov, M. N.; Ahmed, S.; Albrecht, M.; Amoroso, A.; An, F. F.; An, Q.; Bai, J. Z.; Bakina, O.; Baldini Ferroli, R.; Ban, Y.; Bennett, D. W.; Bennett, J. V.; Berger, N.; Bertani, M.; Bettoni, D.; Bian, J. M.; Bianchi, F.; Boger, E.; Boyko, I.; Briere, R. A.; Cai, H.; Cai, X.; Cakir, O.; Calcaterra, A.; Cao, G. F.; Cetin, S. A.; Chai, J.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, J. C.; Chen, M. L.; Chen, P. L.; Chen, S. J.; Chen, X. R.; Chen, Y. B.; Chu, X. K.; Cibinetto, G.; Dai, H. L.; Dai, J. P.; Dbeyssi, A.; Dedovich, D.; Deng, Z. Y.; Denig, A.; Denysenko, I.; Destefanis, M.; de Mori, F.; Ding, Y.; Dong, C.; Dong, J.; Dong, L. Y.; Dong, M. Y.; Dou, Z. L.; Du, S. X.; Duan, P. F.; Fang, J.; Fang, S. S.; Fang, X.; Fang, Y.; Farinelli, R.; Fava, L.; Fegan, S.; Feldbauer, F.; Felici, G.; Feng, C. Q.; Fioravanti, E.; Fritsch, M.; Fu, C. D.; Gao, Q.; Gao, X. L.; Gao, Y.; Gao, Y. G.; Gao, Z.; Garzia, I.; Goetzen, K.; Gong, L.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, S.; Gu, Y. T.; Guo, A. Q.; Guo, L. B.; Guo, R. P.; Guo, Y. P.; Haddadi, Z.; Han, S.; Hao, X. Q.; Harris, F. A.; He, K. L.; He, X. Q.; Heinsius, F. H.; Held, T.; Heng, Y. K.; Holtmann, T.; Hou, Z. L.; Hu, C.; Hu, H. M.; Hu, T.; Hu, Y.; Huang, G. S.; Huang, J. S.; Huang, X. T.; Huang, X. Z.; Huang, Z. L.; Hussain, T.; Ikegami Andersson, W.; Ji, Q.; Ji, Q. P.; Ji, X. B.; Ji, X. L.; Jiang, X. S.; Jiang, X. Y.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Johansson, T.; Julin, A.; Kalantar-Nayestanaki, N.; Kang, X. L.; Kang, X. S.; Kavatsyuk, M.; Ke, B. C.; Khan, T.; Kiese, P.; Kliemt, R.; Koch, L.; Kolcu, O. B.; Kopf, B.; Kornicer, M.; Kuemmel, M.; Kuhlmann, M.; Kupsc, A.; Kühn, W.; Lange, J. S.; Lara, M.; Larin, P.; Lavezzi, L.; Leiber, S.; Leithoff, H.; Leng, C.; Li, C.; Li, Cheng; Li, D. M.; Li, F.; Li, F. Y.; Li, G.; Li, H. B.; Li, H. J.; Li, J. C.; Li, J. Q.; Li, Jin; Li, Kang; Li, Ke; Li, Lei; Li, P. L.; Li, P. R.; Li, Q. Y.; Li, T.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. N.; Li, X. Q.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Lin, D. X.; Liu, B.; Liu, B. J.; Liu, C. X.; Liu, D.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, H. B.; Liu, H. M.; Liu, Huanhuan; Liu, Huihui; Liu, J. B.; Liu, J. P.; Liu, J. Y.; Liu, K.; Liu, K. Y.; Liu, Ke; Liu, L. D.; Liu, P. L.; Liu, Q.; Liu, S. B.; Liu, X.; Liu, Y. B.; Liu, Z. A.; Liu, Zhiqing; Long, Y. F.; Lou, X. C.; Lu, H. J.; Lu, J. G.; Lu, Y.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lyu, X. R.; Ma, F. C.; Ma, H. L.; Ma, L. L.; Ma, M. M.; Ma, Q. M.; Ma, T.; Ma, X. N.; Ma, X. Y.; Ma, Y. M.; Maas, F. E.; Maggiora, M.; Malik, Q. A.; Mao, Y. J.; Mao, Z. P.; Marcello, S.; Messchendorp, J. G.; Mezzadri, G.; Min, J.; Min, T. J.; Mitchell, R. E.; Mo, X. H.; Mo, Y. J.; Morales Morales, C.; Morello, G.; Muchnoi, N. Yu.; Muramatsu, H.; Musiol, P.; Mustafa, A.; Nefedov, Y.; Nerling, F.; Nikolaev, I. B.; Ning, Z.; Nisar, S.; Niu, S. L.; Niu, X. Y.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Pan, Y.; Papenbrock, M.; Patteri, P.; Pelizaeus, M.; Pellegrino, J.; Peng, H. P.; Peters, K.; Pettersson, J.; Ping, J. L.; Ping, R. G.; Poling, R.; Prasad, V.; Qi, H. R.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, J. J.; Qin, N.; Qin, X. S.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Redmer, C. F.; Richter, M.; Ripka, M.; Rong, G.; Rosner, Ch.; Ruan, X. D.; Sarantsev, A.; Savrié, M.; Schnier, C.; Schoenning, K.; Shan, W.; Shao, M.; Shen, C. P.; Shen, P. X.; Shen, X. Y.; Sheng, H. Y.; Shepherd, M. R.; Song, J. J.; Song, W. M.; Song, X. Y.; Sosio, S.; Sowa, C.; Spataro, S.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, X. H.; Sun, Y. J.; Sun, Y. K.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, G. Y.; Tang, X.; Tapan, I.; Tiemens, M.; Tsednee, B.; Uman, I.; Varner, G. S.; Wang, B.; Wang, B. L.; Wang, D.; Wang, D. Y.; Wang, Dan; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, Meng; Wang, P.; Wang, P. L.; Wang, W. P.; Wang, X. F.; Wang, Y.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. H.; Wang, Z. Y.; Wang, Zongyuan; Weber, T.; Wei, D. H.; Weidenkaff, P.; Wen, S. P.; Wiedner, U.; Wolke, M.; Wu, L. H.; Wu, L. J.; Wu, Z.; Xia, L.; Xia, X.; Xia, Y.; Xiao, D.; Xiao, H.; Xiao, Y. J.; Xiao, Z. J.; Xie, Y. G.; Xie, Y. H.; Xiong, X. A.; Xiu, Q. L.; Xu, G. F.; Xu, J. J.; Xu, L.; Xu, Q. J.; Xu, Q. N.; Xu, X. P.; Yan, L.; Yan, W. B.; Yan, W. C.; Yan, Y. H.; Yang, H. J.; Yang, H. X.; Yang, L.; Yang, Y. H.; Yang, Y. X.; Yang, Yifan; Ye, M.; Ye, M. H.; Yin, J. H.; You, Z. Y.; Yu, B. X.; Yu, C. X.; Yu, J. S.; Yuan, C. Z.; Yuan, Y.; Yuncu, A.; Zafar, A. A.; Zallo, A.; Zeng, Y.; Zeng, Z.; Zhang, B. X.; Zhang, B. Y.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J.; Zhang, J. L.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, K.; Zhang, L.; Zhang, S. Q.; Zhang, X. Y.; Zhang, Y. H.; Zhang, Y. T.; Zhang, Yang; Zhang, Yao; Zhang, Yu; Zhang, Z. H.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, J. W.; Zhao, J. Y.; Zhao, J. Z.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, S. J.; Zhao, T. C.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, W. J.; Zheng, Y. H.; Zhong, B.; Zhou, L.; Zhou, X.; Zhou, X. K.; Zhou, X. R.; Zhou, X. Y.; Zhou, Y. X.; Zhu, J.; Zhu, K.; Zhu, K. J.; Zhu, S.; Zhu, S. H.; Zhu, X. L.; Zhu, Y. C.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zotti, L.; Zou, B. S.; Zou, J. H.; Besiii Collaboration

2018-04-01

We investigate the process e+e-→K K ¯J /ψ at center-of-mass energies from 4.189 to 4.600 GeV using 4.7 fb-1 of data collected by the BESIII detector at the BEPCII collider. The Born cross sections for the reactions e+e-→K+K-J /ψ and KS0KS0J /ψ are measured as a function of center-of-mass energy. The energy dependence of the cross section for e+e-→K+K-J /ψ is shown to differ from that for π+π-J /ψ in the region around the Y (4260 ). In addition, there is evidence for a structure around 4.5 GeV in the e+e-→K+K-J /ψ cross section that is not present in π+π-J /ψ .

Experimental and evaluated photoneutron cross sections for 197Au

NASA Astrophysics Data System (ADS)

Varlamov, V.; Ishkhanov, B.; Orlin, V.

2017-10-01

There is a serious well-known problem of noticeable disagreements between the partial photoneutron cross sections obtained in various experiments. Such data were mainly determined using quasimonoenergetic annihilation photon beams and the method of neutron multiplicity sorting at Lawrence Livermore National Laboratory (USA) and Centre d'Etudes Nucleaires of Saclay (France). The analysis of experimental cross sections employing new objective physical data reliability criteria has shown that many of those are not reliable. The IAEA Coordinated Research Project (CRP) on photonuclear data evaluation was approved. The experimental and previously evaluated cross sections of the partial photoneutron reactions (γ ,1 n ) and (γ ,2 n ) on 197Au were analyzed using the new data reliability criteria. The data evaluated using the new experimental-theoretical method noticeably differ from both experimental data and data previously evaluated using nuclear modeling codes gnash, gunf, alice-f, and others. These discrepancies needed to be resolved.

Comparison of the Z$$/\\gamma^{*}$$ + jets to $$\\gamma$$ + jets cross sections in pp collisions at $$\\sqrt{s}$$ = 8 TeV

DOE PAGES

Khachatryan, Vardan

2015-10-20

In this study, a comparison of the differential cross sections for the processes Z/γ * + jets and photon (γ)+jets is presented. The measurements are based on data collected with the CMS detector at √s = 8 TeV corresponding to an integrated luminosity of 19.7 fb –1. The differential cross sections and their ratios are presented as functions of p T. The measurements are also shown as functions of the jet multiplicity. Differential cross sections are obtained as functions of the ratio of the Z/γ* p T to the sum of all jet transverse momenta and of the ratio ofmore » the Z/γ* p T to the leading jet transverse momentum. The data are corrected for detector effects and are compared to simulations based on several QCD calculations.« less

Measurement of e + e − → K K ¯ J / ψ cross sections at center-of-mass energies from 4.189 to 4.600 GeV

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

Ablikim, M.; Achasov, M. N.; Ahmed, S.

2018-04-01

We investigate the process e+e ! K K J= at center-of-mass energies from 4.189 to 4.600 GeV using 4.7 fb1 of data collected by the BESIII detector at the BEPCII collider. The Born cross sections for the reactions e+e ! K+KJ= and K0S K0S J= are measured as a function of center- of-mass energy. The energy dependence of the cross section for e+e ! K+KJ= is shown to di er from that for +J= in the region around the Y (4260). In addition, there is evidence for a structure around 4.5 GeV in the e+e ! K+KJ= cross section thatmore » is not present in +J= .« less

Evaluation of Production Cross Sections of Li, Be, B in CR

NASA Technical Reports Server (NTRS)

Moskalenko, I. V.; Mashnik, S. G.

2003-01-01

Accurate evaluation of the production cross section of light elements is important for models of cosmic ray (CR) propagation, galactic chemical evolution, and cosmological studies. However, the experimental spallation cross section data are scarce and often unavailable to CR community while semi-empirical systematics are frequently wrong by a significant factor. Running sophisticated nuclear codes is not an option of choice for everyone either. We use the Los Alamos versions of the Quark-Gluon String Model code LAQGSM and the improved Cascade-Exciton Model code CEM2k together with all available data from Los Alamos Nuclear Laboratory (LANL) nuclear database to produce evaluated production cross sections of isotopes of Li, Be, and B suitable for astrophysical applications. The LAQGSM and CEM2k models have been shown to reproduce well nuclear reactions and hadronic data in the range 0.01-800 GeV/nucleon.

Mechanisms of SN2 reactions: insights from a nearside/farside analysis.

PubMed

Hennig, Carsten; Schmatz, Stefan

2015-10-28

A nearside/farside analysis of differential cross sections has been performed for the complex-forming SN2 reaction Cl(-) + CH3Br → ClCH3 + Br(-). It is shown that for low rotational quantum numbers a direct "nearside" reaction mechanism plays an important role and leads to anisotropic differential cross sections. For high rotational quantum numbers, indirect mechanisms via a long-lived intermediate complex are prevalent (independent of a nearside/farside configuration), leading to isotropic cross sections. Quantum mechanical interference can be significant at specific energies or angles. Averaging over energies and angles reveals that the nearside/farside decomposition in a semiclassical interpretation can reasonably account for the analysis of the reaction mechanism.

Statistical Model Analysis of (n,p) Cross Sections and Average Energy For Fission Neutron Spectrum

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

Odsuren, M.; Khuukhenkhuu, G.

2011-06-28

Investigation of charged particle emission reaction cross sections for fast neutrons is important to both nuclear reactor technology and the understanding of nuclear reaction mechanisms. In particular, the study of (n,p) cross sections is necessary to estimate radiation damage due to hydrogen production, nuclear heating and transmutations in the structural materials of fission and fusion reactors. On the other hand, it is often necessary in practice to evaluate the neutron cross sections of the nuclides for which no experimental data are available.Because of this, we carried out the systematical analysis of known experimental (n,p) and (n,a) cross sections for fastmore » neutrons and observed a systematical regularity in the wide energy interval of 6-20 MeV and for broad mass range of target nuclei. To explain this effect using the compound, pre-equilibrium and direct reaction mechanisms some formulae were deduced. In this paper, in the framework of the statistical model known experimental (n,p) cross sections averaged over the thermal fission neutron spectrum of U-235 are analyzed. It was shown that the experimental data are satisfactorily described by the statistical model. Also, in the case of (n,p) cross sections the effective average neutron energy for fission spectrum of U-235 was found to be around 3 MeV.« less

Photo-ionization cross-section of donor-related in (In,Ga)N/GaN core/shell under hydrostatic pressure and electric field effects

NASA Astrophysics Data System (ADS)

El Ghazi, Haddou; John Peter, A.

2017-04-01

Hydrogenic-like donor-impurity related self and induced polarizations, bending energy and photo-ionization cross section in spherical core/shell zinc blende (In,Ga)N/GaN are computed. Based on the variational approach and within effective-mass and one parabolic approximations, the calculations are made under finite potential barrier taking into account of the discontinuity of the effective-mass and the constant dielectric. The photo-ionization cross section is studied according to the photon incident energy considering the effects of hydrostatic pressure, applied electric field, structure's radius, impurity's position and indium composition in the core. It is obtained that the influences mentioned above lead to either blue shifts or redshifts of the resonant peak of the photo-ionization cross section spectrum. The unusual behavior related to the structure radius is discussed which is as a consequence of the finite potential confinement. We have shown that the photo-ionization cross section can be controlled with adjusting the internal and external factors. These properties can be useful for producing some device applications such as quantum dot infrared photodetectors.

Single meson production in photon-photon collisions and infrared renormalons

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

Ahmadov, A. I.; Department of Theoretical Physics, Baku State University, Z. Khalilov Street 23, AZ-1148, Baku; Aydin, Coskun

2010-03-01

In this article, we investigate the contribution of the higher-twist Feynman diagrams to the large-p{sub T} inclusive single meson production cross section in photon-photon collisions and present the general formulas for the higher-twist differential cross sections in case of the running coupling and frozen coupling approaches. The structure of infrared renormalon singularities of the higher-twist subprocess cross section and the resummed expression (the Borel sum) for it are found. We compared the resummed higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. We obtain, that ratio R=({Sigma}{sub M}{sup +HT}){sup res}/({Sigma}{submore » M}{sup +HT}){sup 0}, for all values of the transverse momentum p{sub T} of the meson identically equivalent to ratio r=({Delta}{sub M}{sup HT}){sup res}/({Delta}{sub M}{sup HT}){sup 0}. It is shown that the resummed result depends on the choice of the meson wave functions used in calculation. Phenomenological effects of the obtained results are discussed.« less

Infrared renormalons and single meson production in proton-proton collisions

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

Ahmadov, A. I.; Aydin, Coskun; Hakan, Yilmaz A.

2009-07-01

In this article, we investigate the contribution of the higher-twist Feynman diagrams to the large-p{sub T} inclusive pion production cross section in proton-proton collisions and present the general formulas for the higher-twist differential cross sections in the case of the running coupling and frozen coupling approaches. The structure of infrared renormalon singularities of the higher-twist subprocess cross section and the resummed expression (the Borel sum) for it are found. We compared the resummed higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. We obtain, that ratio R=({sigma}{sub {pi}{sup +}}{sup HT}){supmore » res}/({sigma}{sub {pi}{sup +}}{sup HT}){sup 0}, for all values of the transverse momentum p{sub T} of the pion identically equivalent to ratio r=({delta}{sub {pi}}{sup HT}){sup res}/({delta}{sub {pi}}{sup HT}){sup 0}. It is shown that the resummed result depends on the choice of the meson wave functions used in calculation. Phenomenological effects of the obtained results are discussed.« less

Special Course on Fundamentals of Fighter Aircraft Design

DTIC Science & Technology

1987-10-01

mounted centrally on a cylindrical fuselage of circular cross-section. Here the fuselage interference is shown by a calculation with an exact...M. and Schiff, L.B., "Aerodynamic Mathematical Modeling - Basic Concepts", AGARD-LS-114, 1981, Lecture 1. 30. Malcolm, G.N., "Rotary and Magnus ...thin cylindrical Intake 1.5.3. Real Intake equivalence 1.5.4. Lip thickness and auxiliary intake design 1.6. AIR INTAKE RADAR CROSS SECTION (R.C.S

Total γ ⋆ }γ {⋆ cross section and the QCD dipole picture

NASA Astrophysics Data System (ADS)

Bialas, A.; Czyz, W.; Florkowski, W.

1998-05-01

In the framework of the dipole picture of the BFKL pomeron we discuss two possibilities of calculating the total γ^{star}γ^{star} cross section of the virtual photons. It is shown that the dipole model reproduces the results obtained earlier from k_T-factorization up to the selection of the scale determining the length of the QCD cascade. The choice of scale turns out to be important for the numerical outcome of the calculations.

Hadroproduction of heavy quarkonia at the LHC

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

Berezhnoy, A. V., E-mail: Alexander.Berezhnoy@cern.ch; Likhoded, A. K., E-mail: Anatolii.Likhoded@ihep.ru; Luchinsky, A. V., E-mail: Alexey.Luchinsky@ihep.ru

2015-05-15

The production of heavy quarkonia at the LHC is considered. It is shown that, in the case of the inclusive production of χ{sub cJ}P-wave charmonia, existing experimental data can be described upon taking into account next-to-leading corrections, a dominant contribution coming from color-singlet states. For the case of B{sub c}-meson production, it is shown that, at experimentally accessible values of the transverse momentum, power-law corrections to the cross section make a significant contribution, with the result that the cross-section ratio σ(B{sub c})/σ(B) develops a p{sub T} dependence not observed in the fragmentation regime. The case of double vector-charmonium production ismore » also considered.« less

Study of scattering cross section of a plasma column using Green's function volume integral equation method

NASA Astrophysics Data System (ADS)

Soltanmoradi, Elmira; Shokri, Babak

2017-05-01

In this article, the electromagnetic wave scattering from plasma columns with inhomogeneous electron density distribution is studied by the Green's function volume integral equation method. Due to the ready production of such plasmas in the laboratories and their practical application in various technological fields, this study tries to find the effects of plasma parameters such as the electron density, radius, and pressure on the scattering cross-section of a plasma column. Moreover, the incident wave frequency influence of the scattering pattern is demonstrated. Furthermore, the scattering cross-section of a plasma column with an inhomogeneous collision frequency profile is calculated and the effect of this inhomogeneity is discussed first in this article. These results are especially used to determine the appropriate conditions for radar cross-section reduction purposes. It is shown that the radar cross-section of a plasma column reduces more for a larger collision frequency, for a relatively lower plasma frequency, and also for a smaller radius. Furthermore, it is found that the effect of the electron density on the scattering cross-section is more obvious in comparison with the effect of other plasma parameters. Also, the plasma column with homogenous collision frequency can be used as a better shielding in contrast to its inhomogeneous counterpart.

Cross-section fluctuations in chaotic scattering systems.

PubMed

Ericson, Torleif E O; Dietz, Barbara; Richter, Achim

2016-10-01

Exact analytical expressions for the cross-section correlation functions of chaotic scattering systems have hitherto been derived only under special conditions. The objective of the present article is to provide expressions that are applicable beyond these restrictions. The derivation is based on a statistical model of Breit-Wigner type for chaotic scattering amplitudes which has been shown to describe the exact analytical results for the scattering (S)-matrix correlation functions accurately. Our results are given in the energy and in the time representations and apply in the whole range from isolated to overlapping resonances. The S-matrix contributions to the cross-section correlations are obtained in terms of explicit irreducible and reducible correlation functions. Consequently, the model can be used for a detailed exploration of the key features of the cross-section correlations and the underlying physical mechanisms. In the region of isolated resonances, the cross-section correlations contain a dominant contribution from the self-correlation term. For narrow states the self-correlations originate predominantly from widely spaced states with exceptionally large partial width. In the asymptotic region of well-overlapping resonances, the cross-section autocorrelation functions are given in terms of the S-matrix autocorrelation functions. For inelastic correlations, in particular, the Ericson fluctuations rapidly dominate in that region. Agreement with known analytical and experimental results is excellent.

Unified nonlinear analysis for nonhomogeneous anisotropic beams with closed cross sections

NASA Technical Reports Server (NTRS)

Atilgan, Ali R.; Hodges, Dewey H.

1991-01-01

A unified methodology for geometrically nonlinear analysis of nonhomogeneous, anisotropic beams is presented. A 2D cross-sectional analysis and a nonlinear 1D global deformation analysis are derived from the common framework of a 3D, geometrically nonlinear theory of elasticity. The only restrictions are that the strain and local rotation are small compared to unity and that warping displacements are small relative to the cross-sectional dimensions. It is concluded that the warping solutions can be affected by large deformation and that this could alter the incremental stiffnes of the section. It is shown that sectional constants derived from the published, linear analysis can be used in the present nonlinear, 1D analysis governing the global deformation of the beam, which is based on intrinsic equations for nonlinear beam behavior. Excellent correlation is obtained with published experimental results for both isotropic and anisotropic beams undergoing large deflections.

Application of JAERI quantum molecular dynamics model for collisions of heavy nuclei

NASA Astrophysics Data System (ADS)

Ogawa, Tatsuhiko; Hashimoto, Shintaro; Sato, Tatsuhiko; Niita, Koji

2016-06-01

The quantum molecular dynamics (QMD) model incorporated into the general-purpose radiation transport code PHITS was revised for accurate prediction of fragment yields in peripheral collisions. For more accurate simulation of peripheral collisions, stability of the nuclei at their ground state was improved and the algorithm to reject invalid events was modified. In-medium correction on nucleon-nucleon cross sections was also considered. To clarify the effect of this improvement on fragmentation of heavy nuclei, the new QMD model coupled with a statistical decay model was used to calculate fragment production cross sections of Ag and Au targets and compared with the data of earlier measurement. It is shown that the revised version can predict cross section more accurately.

Computational study of duct and pipe flows using the method of pseudocompressibility

NASA Technical Reports Server (NTRS)

Williams, Robert W.

1991-01-01

A viscous, three-dimensional, incompressible, Navier-Stokes Computational Fluid Dynamics code employing pseudocompressibility is used for the prediction of laminar primary and secondary flows in two 90-degree bends of constant cross section. Under study are a square cross section duct bend with 2.3 radius ratio and a round cross section pipe bend with 2.8 radius ratio. Sensitivity of predicted primary and secondary flow to inlet boundary conditions, grid resolution, and code convergence is investigated. Contour and velocity versus spanwise coordinate plots comparing prediction to experimental data flow components are shown at several streamwise stations before, within, and after the duct and pipe bends. Discussion includes secondary flow physics, computational method, computational requirements, grid dependence, and convergence rates.

Two-photon absorption spectrum of the photoinitiator Lucirin TPO-L

NASA Astrophysics Data System (ADS)

Mendonca, C. R.; Correa, D. S.; Baldacchini, T.; Tayalia, P.; Mazur, E.

2008-03-01

Two-photon absorption induced polymerization provides a powerful method for the fabrication of intricate three-dimensional microstructures. Recently, Lucirin TPO-L was shown to be a photoinitiator with several advantageous properties for two-photon induced polymerization. Here we measure the two-photon absorption cross-section spectrum of Lucirin TPO-L, which presents a maximum of 1.2 GM at 610 nm. Despite its small two-photon absorption cross-section, it is possible to fabricate excellent microstructures by two-photon polymerization due to the high polymerization quantum yield of Lucirin TPO-L. These results indicate that optimization of the two-photon absorption cross-section is not the only material parameter to be considered when searching for new photoinitiators for microfabrication via two-photon absorption.

Plasma Physics Issues in Gas Discharge Laser Development

DTIC Science & Technology

1991-12-01

possible where the ArF exciplex was previously formed by 2 3 4 5 6 7 8 reactions analogous to those shown above. These formation R (1) reactions are...exothermic bv a few to many electronvolts. Fig. n. Energy levels of the K’F exciplex . Laser oscillation at 248 nm takes resulting in KrF(B. v) being formed...all on a due to the large momentum-transfer cross section of the Rg single device. which forms the exciplex . The cross sections for electron- Excited

Kaon-nucleus scattering

NASA Technical Reports Server (NTRS)

Hong, Byungsik; Buck, Warren W.; Maung, Khin M.

1989-01-01

Two kinds of number density distributions of the nucleus, harmonic well and Woods-Saxon models, are used with the t-matrix that is taken from the scattering experiments to find a simple optical potential. The parameterized two body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to imaginary part of the forward elastic scattering amplitude, are shown. The eikonal approximation was chosen as the solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

Double Higgs production at LHC, see-saw type-II and Georgi-Machacek model

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

Godunov, S. I., E-mail: sgodunov@itep.ru; Vysotsky, M. I., E-mail: vysotsky@itep.ru; Zhemchugov, E. V., E-mail: zhemchugov@itep.ru

2015-03-15

The double Higgs production in the models with isospin-triplet scalars is studied. It is shown that in the see-saw type-II model, the mode with an intermediate heavy scalar, pp → H + X → 2h + X, may have the cross section that is comparable with that in the Standard Model. In the Georgi-Machacek model, this cross section could be much larger than in the Standard Model because the vacuum expectation value of the triplet can be large.

On-the-fly Doppler broadening of unresolved resonance region cross sections

DOE PAGES

Walsh, Jonathan A.; Forget, Benoit; Smith, Kord S.; ...

2017-07-29

In this paper, two methods for computing temperature-dependent unresolved resonance region cross sections on-the-fly within continuous-energy Monte Carlo neutron transport simulations are presented. The first method calculates Doppler broadened cross sections directly from zero-temperature average resonance parameters. In a simulation, at each event that requires cross section values, a realization of unresolved resonance parameters is generated about the desired energy and temperature-dependent single-level Breit-Wigner resonance cross sections are computed directly via the analytical Ψ-x Doppler integrals. The second method relies on the generation of equiprobable cross section magnitude bands on an energy-temperature mesh. Within a simulation, the bands are sampledmore » and interpolated in energy and temperature to obtain cross section values on-the-fly. Both of the methods, as well as their underlying calculation procedures, are verified numerically in extensive code-to-code comparisons. Energy-dependent pointwise cross sections calculated with the newly-implemented procedures are shown to be in excellent agreement with those calculated by a widely-used nuclear data processing code. Relative differences at or below 0.1% are observed. Integral criticality benchmark results computed with the proposed methods are shown to reproduce those computed with a state-of-the-art processed nuclear data library very well. In simulations of fast spectrum systems which are highly-sensitive to the representation of cross section data in the unresolved region, k-eigenvalue and neutron flux spectra differences of <10 pcm and <1.0% are observed, respectively. The direct method is demonstrated to be well-suited to the calculation of reference solutions — against which results obtained with a discretized representation may be assessed — as a result of its treatment of the energy, temperature, and cross section magnitude variables as continuous. Also, because there is no pre-processed data to store (only temperature-independent average resonance parameters) the direct method is very memory-efficient. Typically, only a few kB of memory are needed to store all required unresolved region data for a single nuclide. However, depending on the details of a particular simulation, performing URR cross section calculations on-the-fly can significantly increase simulation times. Alternatively, the method of interpolating equiprobable probability bands is demonstrated to produce results that are as accurate as the direct reference solutions, to within arbitrary precision, with high computational efficiency in terms of memory requirements and simulation time. Analyses of a fast spectrum system show that interpolation on a coarse energy-temperature mesh can be used to reproduce reference k-eigenvalue results obtained with cross sections calculated continuously in energy and directly at an exact temperature to within <10 pcm. Probability band data on a mesh encompassing the range of temperatures relevant to reactor analysis usually require around 100 kB of memory per nuclide. Finally, relative to the case in which probability table data generated at a single, desired temperature are used, minor increases in simulation times are observed when probability band interpolation is employed.« less

Augmented Cross-Sectional Studies with Abbreviated Follow-up for Estimating HIV Incidence

PubMed Central

Claggett, B.; Lagakos, S.W.; Wang, R.

2011-01-01

Summary Cross-sectional HIV incidence estimation based on a sensitive and less-sensitive test offers great advantages over the traditional cohort study. However, its use has been limited due to concerns about the false negative rate of the less-sensitive test, reflecting the phenomenon that some subjects may remain negative permanently on the less-sensitive test. Wang and Lagakos (2010) propose an augmented cross-sectional design which provides one way to estimate the size of the infected population who remain negative permanently and subsequently incorporate this information in the cross-sectional incidence estimator. In an augmented cross-sectional study, subjects who test negative on the less-sensitive test in the cross-sectional survey are followed forward for transition into the nonrecent state, at which time they would test positive on the less-sensitive test. However, considerable uncertainty exists regarding the appropriate length of follow-up and the size of the infected population who remain nonreactive permanently to the less-sensitive test. In this paper, we assess the impact of varying follow-up time on the resulting incidence estimators from an augmented cross-sectional study, evaluate the robustness of cross-sectional estimators to assumptions about the existence and the size of the subpopulation who will remain negative permanently, and propose a new estimator based on abbreviated follow-up time (AF). Compared to the original estimator from an augmented cross-sectional study, the AF Estimator allows shorter follow-up time and does not require estimation of the mean window period, defined as the average time between detectability of HIV infection with the sensitive and less-sensitive tests. It is shown to perform well in a wide range of settings. We discuss when the AF Estimator would be expected to perform well and offer design considerations for an augmented cross-sectional study with abbreviated follow-up. PMID:21668904

Augmented cross-sectional studies with abbreviated follow-up for estimating HIV incidence.

PubMed

Claggett, B; Lagakos, S W; Wang, R

2012-03-01

Cross-sectional HIV incidence estimation based on a sensitive and less-sensitive test offers great advantages over the traditional cohort study. However, its use has been limited due to concerns about the false negative rate of the less-sensitive test, reflecting the phenomenon that some subjects may remain negative permanently on the less-sensitive test. Wang and Lagakos (2010, Biometrics 66, 864-874) propose an augmented cross-sectional design that provides one way to estimate the size of the infected population who remain negative permanently and subsequently incorporate this information in the cross-sectional incidence estimator. In an augmented cross-sectional study, subjects who test negative on the less-sensitive test in the cross-sectional survey are followed forward for transition into the nonrecent state, at which time they would test positive on the less-sensitive test. However, considerable uncertainty exists regarding the appropriate length of follow-up and the size of the infected population who remain nonreactive permanently to the less-sensitive test. In this article, we assess the impact of varying follow-up time on the resulting incidence estimators from an augmented cross-sectional study, evaluate the robustness of cross-sectional estimators to assumptions about the existence and the size of the subpopulation who will remain negative permanently, and propose a new estimator based on abbreviated follow-up time (AF). Compared to the original estimator from an augmented cross-sectional study, the AF estimator allows shorter follow-up time and does not require estimation of the mean window period, defined as the average time between detectability of HIV infection with the sensitive and less-sensitive tests. It is shown to perform well in a wide range of settings. We discuss when the AF estimator would be expected to perform well and offer design considerations for an augmented cross-sectional study with abbreviated follow-up. © 2011, The International Biometric Society.

Measurement of e + e - → K K ¯ J / ψ cross sections at center-of-mass energies from 4.189 to 4.600 GeV

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

Ablikim, M.; Achasov, M. N.; Ahmed, S.

We investigate the process e +e - → Kmore » $$\\bar{K}$$J/ψ at center-of-mass energies from 4.189 to 4.600 GeV using 4.7 fb -1 of data collected by the BESIII detector at the BEPCII collider. The Born cross sections for the reactions e +e - → K +K -J/ψ and $$K_s^0$$$K_s^0$$J/ψ are measured as a function of center-of-mass energy. The energy dependence of the cross section for e +e -→ K +K -J/ψ is shown to differ from that for π +π -J/ψ in the region around the Y(4260). In addition, there is evidence for a structure around 4.5 GeV in the e +e - → K +K -J/ψ cross section that is not present in π +π -J/ψ.« less

Pattern of asymmetry of paraspinal muscle size in adolescent idiopathic scoliosis examined by real-time ultrasound imaging. A preliminary study.

PubMed

Kennelly, K P; Stokes, M J

1993-06-01

The symmetry of lumbar multifidus size was examined in 20 patients with adolescent idiopathic scoliosis, aged 12-19 years. With the subject prone, bilateral real-time ultrasound images were obtained at the level of the 4th lumbar vertebra. Cross-sectional area and linear (horizontal and vertical) measurements were made using on-screen calipers. A pattern of asymmetry of lumbar multifidus cross-sectional area was shown to exist for the different curve types. The cross-sectional area was smaller (P < 0.0001) on the opposite side to the convexity of a primary thoracic curve, and on the convex side of a lumbar or thoracolumbar curve. The combined linear measurements (multiplied) correlated with cross-sectional area (r = 0.95) and could therefore be used for rapid clinical assessment of multifidus size. These preliminary findings provide a basis for further investigation of the role of the musculature in the pathogenesis of adolescent idiopathic scoliosis.

Measurement of e + e - → K K ¯ J / ψ cross sections at center-of-mass energies from 4.189 to 4.600 GeV

DOE PAGES

Ablikim, M.; Achasov, M. N.; Ahmed, S.; ...

2018-04-10

We investigate the process e +e - → Kmore » $$\\bar{K}$$J/ψ at center-of-mass energies from 4.189 to 4.600 GeV using 4.7 fb -1 of data collected by the BESIII detector at the BEPCII collider. The Born cross sections for the reactions e +e - → K +K -J/ψ and $$K_s^0$$$K_s^0$$J/ψ are measured as a function of center-of-mass energy. The energy dependence of the cross section for e +e -→ K +K -J/ψ is shown to differ from that for π +π -J/ψ in the region around the Y(4260). In addition, there is evidence for a structure around 4.5 GeV in the e +e - → K +K -J/ψ cross section that is not present in π +π -J/ψ.« less

Production mechanism of new neutron-rich heavy nuclei in the 136Xe +198Pt reaction

NASA Astrophysics Data System (ADS)

Li, Cheng; Wen, Peiwei; Li, Jingjing; Zhang, Gen; Li, Bing; Xu, Xinxin; Liu, Zhong; Zhu, Shaofei; Zhang, Feng-Shou

2018-01-01

The multinucleon transfer reaction of 136Xe +198Pt at Elab = 7.98 MeV/nucleon is investigated by using the improved quantum molecular dynamics model. The quasielastic, deep-inelastic, and quasifission collision mechanisms are studied via analyzing the angular distributions of fragments and the energy dissipation processes during the collisions. The measured isotope production cross sections of projectile-like fragments are reasonably well reproduced by the calculation of the ImQMD model together with the GEMINI code. The isotope production cross sections for the target-like fragments and double differential cross sections of 199Pt, 203Pt, and 208Pt are calculated. It is shown that about 50 new neutron-rich heavy nuclei can be produced via deep-inelastic collision mechanism, where the production cross sections are from 10-3 to 10-6 mb. The corresponding emission angle and the kinetic energy for these new neutron-rich nuclei locate at 40∘-60∘ and 100-200 MeV, respectively.

Robust estimation procedure in panel data model

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

Shariff, Nurul Sima Mohamad; Hamzah, Nor Aishah

2014-06-19

The panel data modeling has received a great attention in econometric research recently. This is due to the availability of data sources and the interest to study cross sections of individuals observed over time. However, the problems may arise in modeling the panel in the presence of cross sectional dependence and outliers. Even though there are few methods that take into consideration the presence of cross sectional dependence in the panel, the methods may provide inconsistent parameter estimates and inferences when outliers occur in the panel. As such, an alternative method that is robust to outliers and cross sectional dependencemore » is introduced in this paper. The properties and construction of the confidence interval for the parameter estimates are also considered in this paper. The robustness of the procedure is investigated and comparisons are made to the existing method via simulation studies. Our results have shown that robust approach is able to produce an accurate and reliable parameter estimates under the condition considered.« less

The flows structure in unsteady gas flow in pipes with different cross-sections

NASA Astrophysics Data System (ADS)

Plotnikov, Leonid; Nevolin, Alexandr; Nikolaev, Dmitrij

2017-10-01

The results of numerical simulation and experimental study of the structure of unsteady flows in pipes with different cross sections are presented in the article. It is shown that the unsteady gas flow in a circular pipe is axisymmetric without secondary currents. Steady vortex structures (secondary flows) are observed in pipes with cross sections in the form of a square and an equilateral triangle. It was found that these secondary flows have a significant impact on gas flows in pipes of complex configuration. On the basis of experimental researches it is established that the strong oscillatory phenomena exist in the inlet pipe of the piston engine arising after the closing of the intake valve. The placement of the profiled plots (with a cross section of a square or an equilateral triangle) in the intake pipe leads to the damping of the oscillatory phenomena and a more rapid stabilization of pulsating flow. This is due to the stabilizing effect of the vortex structures formed in the corners of this configuration.

Beauty production at CDF

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

Shears, Tara; /Liverpool U.

A review of recent measurements of beauty production, based on proton antiproton collision data at {radical}s = 1.96 TeV and using the CDF detector, is given. Previous measurements of beauty (b) quark production at the Tevatron, carried out at centre-of-mass energies {radical}s = 1.8 TeV, have shown discrepancies when compared to Next to Leading Order (NLO) predictions [1]. Improved predictions and experimental procedures have reduced this discrepancy [2]. Improved parton density functions, better fragmentation functions and more complete theoretical calculations have improved theoretical accuracy. Experimentally, measurements of beauty production at {radical}s = 1.96 TeV are now presented in terms ofmore » b hadrons or B mesons, to avoid problems unfolding back to the quark level. In this review [3] measurements of inclusive beauty (where one beauty jet or hadron is reconstructed in the event), and beauty + X (where X can be a boson or another beauty jet or hadron), production will be presented: inclusive beauty jet cross-section; semi and fully reconstructed B meson cross-section; beauty dijet cross-section; semi-reconstructed B B meson cross-section; Z boson + beauty jet cross-section. More information concerning other measurements of heavy quark production can be found elsewhere [4].« less

The effect of carbon crystal structure on treat reactor physics calculations

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

Swanson, R.W.; Harrison, L.J.

1988-01-01

The Transient Reactor Test Facility (TREAT) at Argonne National Laboratory-West (ANL-W) is fueled with urania in a graphite and carbon mixture. This fuel was fabricated from a mixture of graphite flour, thermax (a thermatomic carbon produced by ''cracking'' natural gas), coal-tar resin and U/sub 3/O/sub 8/. During the fabrication process, the fuel was baked to dissociate the resin, but the high temperature necessary to graphitize the carbon in the thermax and in the resin was avoided. Therefore, the carbon crystal structure is a complex mixture of graphite particles in a nongraphitized elemental carbon matrix. Results of calculations using macroscopic carbonmore » cross sections obtained by mixing bound-kernel graphite cross sections for the graphitized carbon and free-gas carbon cross sections for the remainder of the carbon and calculations using only bound-kernel graphite cross sections are compared to experimental data. It is shown that the use of the hybridized cross sections which reflect the allotropic mixture of the carbon in the TREAT fuel results in a significant improvement in the accuracy of calculated neutronics parameters for the TREAT reactor. 6 refs., 2 figs., 3 tabs.« less

Quantum shielding effects on the Gamow penetration factor for nuclear fusion reaction in quantum plasmas

NASA Astrophysics Data System (ADS)

Lee, Myoung-Jae; Jung, Young-Dae

2017-01-01

The quantum shielding effects on the nuclear fusion reaction process are investigated in quantum plasmas. The closed expression of the classical turning point for the Gamow penetration factor in quantum plasmas is obtained by the Lambert W-function. The closed expressions of the Gamow penetration factor and the cross section for the nuclear fusion reaction in quantum plasmas are obtained as functions of the plasmon energy and the relative kinetic energy by using the effective interaction potential with the WKB analysis. It is shown that the influence of quantum screening suppresses the Sommerfeld reaction factor. It is also shown that the Gamow penetration factor increases with an increase of the plasmon energy. It is also shown that the quantum shielding effect enhances the deuterium formation by the proton-proton reaction in quantum plasmas. In addition, it is found that the energy dependences on the reaction cross section and the Gamow penetration factor are more significant in high plasmon-energy domains.

Path length differencing and energy conservation of the S[sub N] Boltzmann/Spencer-Lewis equation

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

Filippone, W.L.; Monahan, S.P.

It is shown that the S[sub N] Boltzmann/Spencer-Lewis equations conserve energy locally if and only if they satisfy particle balance and diamond differencing is used in path length. In contrast, the spatial differencing schemes have no bearing on the energy balance. Energy is conserved globally if it is conserved locally and the multigroup cross sections are energy conserving. Although the coupled electron-photon cross sections generated by CEPXS conserve particles and charge, they do not precisely conserve energy. It is demonstrated that these cross sections can be adjusted such that particles, charge, and energy are conserved. Finally, since a conventional negativemore » flux fixup destroys energy balance when applied to path legend, a modified fixup scheme that does not is presented.« less

Sensitivity analysis of TRX-2 lattice parameters with emphasis on epithermal /sup 238/U capture. Final report

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

Tomlinson, E.T.; deSaussure, G.; Weisbin, C.R.

1977-03-01

The main purpose of the study is the determination of the sensitivity of TRX-2 thermal lattice performance parameters to nuclear cross section data, particularly the epithermal resonance capture cross section of /sup 238/U. An energy-dependent sensitivity profile was generated for each of the performance parameters, to the most important cross sections of the various isotopes in the lattice. Uncertainties in the calculated values of the performance parameters due to estimated uncertainties in the basic nuclear data, deduced in this study, were shown to be small compared to the uncertainties in the measured values of the performance parameter and compared tomore » differences among calculations based upon the same data but with different methodologies.« less

Relativistic effects in the photoionization of hydrogen-like ions with screened Coulomb interaction

NASA Astrophysics Data System (ADS)

Xie, L. Y.; Wang, J. G.; Janev, R. K.

2014-06-01

The relativistic effects in the photoionization of hydrogen-like ion with screened Coulomb interaction of Yukawa type are studied for a broad range of screening lengths and photoelectron energies. The bound and continuum wave functions have been determined by solving the Dirac equation. The study is focused on the relativistic effects manifested in the characteristic features of photoionization cross section for electric dipole nl →ɛ,l±1 transitions: shape resonances, Cooper minima and cross section enhancements due to near-zero-energy states. It is shown that the main source of relativistic effects in these cross section features is the fine-structure splitting of bound state energy levels. The relativistic effects are studied in the photoionization of Fe25+ ion, as an example.

Relativistic effects in the photoionization of hydrogen-like ions with screened Coulomb interaction

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

Xie, L. Y.; Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, P.O. Box 8009-26, Beijing 100088; Wang, J. G.

2014-06-15

The relativistic effects in the photoionization of hydrogen-like ion with screened Coulomb interaction of Yukawa type are studied for a broad range of screening lengths and photoelectron energies. The bound and continuum wave functions have been determined by solving the Dirac equation. The study is focused on the relativistic effects manifested in the characteristic features of photoionization cross section for electric dipole nl→ε,l±1 transitions: shape resonances, Cooper minima and cross section enhancements due to near-zero-energy states. It is shown that the main source of relativistic effects in these cross section features is the fine-structure splitting of bound state energy levels.more » The relativistic effects are studied in the photoionization of Fe{sup 25+} ion, as an example.« less

Atomic Processes and Diagnostics of Low Pressure Krypton Plasma

NASA Astrophysics Data System (ADS)

Srivastava, Rajesh; Goyal, Dipti; Gangwar, Reetesh; Stafford, Luc

2015-03-01

Optical emission spectroscopy along with suitable collisional-radiative (CR) model is used in plasma diagnostics. Importance of reliable cross-sections for various atomic processes is shown for low pressure argon plasma. In the present work, radially-averaged Kr emission lines from the 2pi --> 1sj were recorded as a function of pressure from 1 to 50mTorr. We have developed a CR model using our fine-structure relativistic-distorted wave cross sections. The various processes considered are electron-impact excitation, ionization and their reverse processes. The required rate coefficients have been calculated from these cross-sections assuming Maxwellian energy distribution. Electron temperature obtained from the CR model is found to be in good agreement with the probe measurements. Work is supported by IAEA Vienna, DAE-BRNS Mumbai and CSIR, New Delhi.

Cosmogenic rare gases and 10-Be in a cross section of Knyahinya

NASA Technical Reports Server (NTRS)

Wieler, R.; Signer, P.; Herpers, U.; Sarafin, R.; Bonani, G.; Hofmann, H. J.; Morenzoni, E.; Nessi, M.; Suter, M.; Woelfli, W.

1986-01-01

The concentrations of cosmogenic nuclides were studied as a function of shielding on samples from a cross section of the 293 kg main fragment of the L5 chondrite Knyahinya. The stone broke into two nearly symmetrical parts upon its fall in 1866. The planar cross section has diameters between 40 and 55 cm. He, Ne, and Ar were measured on about 20 samples by mass spectrometry and the 10-Be activities on aliquots of 10 selected samples were determined by AMS. The 10-Be data are presented and the abundances of spallogenic nuclides are compared with the model calculations reported by Reedy for spherical L chondrites. The 10-Be production rates in Knyahinya are shown versus the shielding parameter 22-Ne/21-Ne.

Scaling of cross sections for K-electron capture by high-energy protons and alpha-particles from the multielectron atoms

NASA Technical Reports Server (NTRS)

Omidvar, K.

1976-01-01

Electron capture by protons from H, He, and the K-shell of Ar, and alpha particles from He are considered. It is shown that when a certain function of the experimental cross sections is plotted versus the inverse of the collision energy, at high energies the function falls on a straight line. At lower energies the function concaves up or down, depending on the charge of the projectile, the effective charge and the ionization potential of the electron that is being captured. The plot can be used to predict cross sections where experimental data are not available, and as a guide in future experiments. High energy scaling formulas for K-electron capture by low-charge projectiles are given.

Rotationally and vibrationally inelastic scattering in the rotational IOS approximation. Ultrasimple calculation of total (differential, integral, and transport) cross sections for nonspherical molecules

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

Parker, G.A.; Pack, R.T

1978-02-15

A simple, direct derivation of the rotational infinite order sudden (IOS) approximation in molecular scattering theory is given. Connections between simple scattering amplitude formulas, choice of average partial wave parameter, and magnetic transitions are reviewed. Simple procedures for calculating cross sections for specific transitions are discussed and many older model formulas are given clear derivations. Total (summed over rotation) differential, integral, and transport cross sections, useful in the analysis of many experiments involving nonspherical molecules, are shown to be exceedingly simple: They are just averages over the potential angle of cross sections calculated using simple structureless spherical particle formulas andmore » programs. In the case of vibrationally inelastic scattering, the IOSA, without further approximation, provides a well-defined way to get fully three dimensional cross sections from calculations no more difficult than collinear calculations. Integral, differential, viscosity, and diffusion cross sections for He-CO/sub 2/ obtained from the IOSA and a realistic intermolecular potential are calculated as an example and compared with experiment. Agreement is good for the complete potential but poor when only its spherical part is used, so that one should never attempt to treat this system with a spherical model. The simplicity and accuracy of the IOSA make it a viable method for routine analysis of experiments involving collisions of nonspherical molecules.« less

Effect of multiple spin species on spherical shell neutron transmission analysis

NASA Technical Reports Server (NTRS)

Semler, T. T.

1972-01-01

A series of Monte Carlo calculations were performed in order to evaluate the effect of separated against merged spin statistics on the analysis of spherical shell neutron transmission experiments for gold. It is shown that the use of separated spin statistics results in larger average capture cross sections of gold at 24 KeV. This effect is explained by stronger windows in the total cross section caused by the interference between potential and J(+) resonances and by J(+) and J(-) resonance overlap allowed by the use of separated spin statistics.

Direct measurements of nonlinear absorption and refraction in solutions of phthalocyanines

NASA Technical Reports Server (NTRS)

Wei, T. H.; Hagan, D. J.; Sence, M. J.; Van Stryland, E. W.; Perry, J. W.; Coulter, D. R.

1992-01-01

Direct measurements are reported of the excited singlet-state absorption cross section and the associated nonlinear refractive cross section using picosecond pulses at 532 nm in solutions of phthalocyanine and naphthalocyanine dyes. By monitoring the transmittance and far-field spatial beam distortion for different pulsewidths in the picosecond regime, it is shown that both the nonlinear absorption and refraction are fluence (energy-per-unit-area) rather than irradiance dependent. Thus, excited-state absorption is the dominant nonlinear absorption process, and the observed nonlinear refraction is also due to real population excitation.

Topology of large-scale structure. IV - Topology in two dimensions

NASA Technical Reports Server (NTRS)

Melott, Adrian L.; Cohen, Alexander P.; Hamilton, Andrew J. S.; Gott, J. Richard, III; Weinberg, David H.

1989-01-01

In a recent series of papers, an algorithm was developed for quantitatively measuring the topology of the large-scale structure of the universe and this algorithm was applied to numerical models and to three-dimensional observational data sets. In this paper, it is shown that topological information can be derived from a two-dimensional cross section of a density field, and analytic expressions are given for a Gaussian random field. The application of a two-dimensional numerical algorithm for measuring topology to cross sections of three-dimensional models is demonstrated.

Modeling of the Magnetization Behavior of Realistic Self-Organized InAs/GaAs Quantum Craters as Observed with Cross-Sectional STM

NASA Astrophysics Data System (ADS)

Fomin, V. M.; Gladilin, V. N.; Devreese, J. T.; Offermans, P.; Koenraad, P. M.; Wolter, J. H.; García, J. M.; Granados, D.

2005-06-01

Recently, using cross-sectional scanning-tunneling microscopy (X-STM), it was shown that self-organized ring-like InAs quantum dots are much smaller in diameter than it is expected from atomic force microscopy measurements and, moreover, that they possess a depression rather than an opening in the central region. For those quantum craters, we analyze the possibility to reveal the electronic properties (like the Aharonov-Bohm oscillations) peculiar to doubly connected geometry of quantum rings.

Visualizing Cross-sectional Data in a Real-World Context

NASA Astrophysics Data System (ADS)

Van Noten, K.; Lecocq, T.

2016-12-01

If you could fly around your research results in three dimensions, wouldn't you like to do it? Visualizing research results properly during scientific presentations already does half the job of informing the public on the geographic framework of your research. Many scientists use the Google Earth™ mapping service (V7.1.2.2041) because it's a great interactive mapping tool for assigning geographic coordinates to individual data points, localizing a research area, and draping maps of results over Earth's surface for 3D visualization. However, visualizations of research results in vertical cross-sections are often not shown simultaneously with the maps in Google Earth. A few tutorials and programs to display cross-sectional data in Google Earth do exist, and the workflow is rather simple. By importing a cross-sectional figure into in the open software SketchUp Make [Trimble Navigation Limited, 2016], any spatial model can be exported to a vertical figure in Google Earth. In this presentation a clear workflow/tutorial is presented how to image cross-sections manually in Google Earth. No software skills, nor any programming codes are required. It is very easy to use, offers great possibilities for teaching and allows fast figure manipulation in Google Earth. The full workflow can be found in "Van Noten, K. 2016. Visualizing Cross-Sectional Data in a Real-World Context. EOS, Transactions AGU, 97, 16-19".The video tutorial can be found here: https://www.youtube.com/watch?v=Tr8LwFJ4RYU&Figure: Cross-sectional Research Examples Illustrated in Google Earth

Heavy residues from very mass asymmetric heavy ion reactions

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

Hanold, Karl Alan

1994-08-01

The isotopic production cross sections and momenta of all residues with nuclear charge (Z) greater than 39 from the reaction of 26, 40, and 50 MeV/nucleon 129Xe + Be, C, and Al were measured. The isotopic cross sections, the momentum distribution for each isotope, and the cross section as a function of nuclear charge and momentum are presented here. The new cross sections are consistent with previous measurements of the cross sections from similar reaction systems. The shape of the cross section distribution, when considered as a function of Z and velocity, was found to be qualitatively consistent with thatmore » expected from an incomplete fusion reaction mechanism. An incomplete fusion model coupled to a statistical decay model is able to reproduce many features of these reactions: the shapes of the elemental cross section distributions, the emission velocity distributions for the intermediate mass fragments, and the Z versus velocity distributions. This model gives a less satisfactory prediction of the momentum distribution for each isotope. A very different model based on the Boltzman-Nordheim-Vlasov equation and which was also coupled to a statistical decay model reproduces many features of these reactions: the shapes of the elemental cross section distributions, the intermediate mass fragment emission velocity distributions, and the Z versus momentum distributions. Both model calculations over-estimate the average mass for each element by two mass units and underestimate the isotopic and isobaric widths of the experimental distributions. It is shown that the predicted average mass for each element can be brought into agreement with the data by small, but systematic, variation of the particle emission barriers used in the statistical model. The predicted isotopic and isobaric widths of the cross section distributions can not be brought into agreement with the experimental data using reasonable parameters for the statistical model.« less

New potentialities of the Liège intranuclear cascade model for reactions induced by nucleons and light charged particles

NASA Astrophysics Data System (ADS)

Boudard, A.; Cugnon, J.; David, J.-C.; Leray, S.; Mancusi, D.

2013-01-01

The new version (incl4.6) of the Liège intranuclear cascade (INC) model for the description of spallation reactions is presented in detail. Compared to the standard version (incl4.2), it incorporates several new features, the most important of which are: (i) the inclusion of cluster production through a dynamical phase space coalescence model, (ii) the Coulomb deflection for entering and outgoing charged particles, (iii) the improvement of the treatment of Pauli blocking and of soft collisions, (iv) the introduction of experimental threshold values for the emission of particles, (v) the improvement of pion dynamics, (vi) a detailed procedure for the treatment of light-cluster-induced reactions taking care of the effects of binding energy of the nucleons inside the incident cluster and of the possible fusion reaction at low energy. Performances of the new model concerning nucleon-induced reactions are illustrated by a comparison with experimental data covering total reaction cross sections, neutron, proton, pion, and composite double-differential cross-sections, neutron multiplicities, residue mass and charge distributions, and residue recoil velocity distributions. Whenever necessary, the incl4.6 model is coupled to the ABLA07 de-excitation model and the respective merits of the two models are then tentatively disentangled. Good agreement is generally obtained in the 200 MeV to 2 GeV range. Below 200 MeV and down to a few tens of MeV, the total reaction cross section is well reproduced and differential cross sections are reasonably well described. The model is also tested for light-ion induced reactions at low energy, below 100 MeV incident energy per nucleon. Beyond presenting the update of the incl4.2 model, attention has been paid to applications of the new model to three topics for which some particular aspects are discussed for the first time. The first topic is the production of clusters heavier than alpha particle. It is shown that the energy spectra of these produced clusters are consistent with coalescence. The second topic regards the longitudinal residue recoil velocity and its fluctuations. Excellent results are obtained for these quantities. It addition, it is shown that the distributions of these quantities display typical random-walk characteristics, at least for not-too-large mass losses. They are interpreted as a direct consequence of the independence of successive binary collisions occurring during the cascade process. The last topic concerns the total reaction cross section and the residue-production cross sections for low-energy incident light ions. It is shown that our new model can give a rather satisfactory account of these cross sections, offering so an alternative to fusion models and the advantage of a single model for the progressive change from fusion to pre-equilibrium mechanisms.

Coincidence charged-current neutrino-induced deuteron disintegration for H 2 2 O 16

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

Van Orden, J. W.; Donnelly, T. W.; Moreno, O.

Semi-inclusive charge-changing neutrino reactions on targets of heavy water are investigated with the goal of determining the relative contributions to the total cross section of deuterium and oxygen in kinematics chosen to emphasize the former. The study is undertaken for conditions where the typical neutrino beam energies are in the few GeV region, and hence relativistic modeling is essential. For this, the previous relativistic approach for the deuteron is employed, together with a spectral function approach for the case of oxygen. Upon optimizing the kinematics of the final-state particles assumed to be detected (typically a muon and a proton) it is shown that the oxygen contribution to the total cross section is suppressed by roughly an order or magnitude compared with the deuterium cross section, thereby confirming that CCmore » $$\

Absolute and relative cross section measurements of 237Np(n,f) and 238U(n,f) at the National Physical Laboratory

NASA Astrophysics Data System (ADS)

Salvador-Castiñeira, Paula; Hambsch, Franz-Josef; Göök, Alf; Vidali, Marzio; Hawkes, Nigel P.; Roberts, Neil J.; Taylor, Graeme C.; Thomas, David J.

2017-09-01

Cross section measurements in the fast energy region are being demanded as one of the key ingredients for modelling Generation-IV nuclear power plants. However, in facilities where there are no time-of-flight possibilities or it is not convenient to use them, using the 235U(n,f) cross section as a benchmark would require a careful knowledge of the room scatter in the experimental area. In this paper we present measurements of two threshold reactions, 238U(n,f) and 237Np(n,f), that could become a standard between their fission threshold and 2.5 MeV, if the discrepancies shown in the evaluations and in some experimental data can be solved. The preliminary results are in agreement with the present ENDF/B-VII.1 evaluation.

Coincidence charged-current neutrino-induced deuteron disintegration for H 2 2 O 16

DOE PAGES

Van Orden, J. W.; Donnelly, T. W.; Moreno, O.

2017-12-26

Semi-inclusive charge-changing neutrino reactions on targets of heavy water are investigated with the goal of determining the relative contributions to the total cross section of deuterium and oxygen in kinematics chosen to emphasize the former. The study is undertaken for conditions where the typical neutrino beam energies are in the few GeV region, and hence relativistic modeling is essential. For this, the previous relativistic approach for the deuteron is employed, together with a spectral function approach for the case of oxygen. Upon optimizing the kinematics of the final-state particles assumed to be detected (typically a muon and a proton) it is shown that the oxygen contribution to the total cross section is suppressed by roughly an order or magnitude compared with the deuterium cross section, thereby confirming that CCmore » $$\

Theory of twisted nonuniformly heated bars

NASA Technical Reports Server (NTRS)

Shorr, B. F.

1980-01-01

Nonlineary distributed stresses in twisted nonuniformly heated bars of arbitrary cross section are calculated taking into account various elasticity parameters. The approximate theory is shown to be sufficiently general and accurate by comparison with experimental data.

Development of Laser Scanner for Full Cross-Sectional Deformation Monitoring of Underground Gateroads

PubMed Central

Yang, Qianlong; Zhang, Zhenyu; Liu, Xiaoqian; Ma, Shuqi

2017-01-01

The deformation of underground gateroads tends to be asymmetric and complex. Traditional instrumentation fails to accurately and conveniently monitor the full cross-sectional deformation of underground gateroads. Here, a full cross-sectional laser scanner was developed, together with a visualization software package. The developed system used a polar coordinate measuring method and the full cross-sectional measurement was shown by 360° rotation of a laser sensor driven by an electrical motor. Later on, the potential impact of gateroad wall flatness, roughness, and geometrical profile, as well as coal dust environment on the performance of the developed laser scanner will be evaluated. The study shows that high-level flatness is favorable in the application of the developed full cross-sectional deformation monitoring system. For a smooth surface of gateroad, the sensor cannot receive reflected light when the incidence angle of laser beam is large, causing data loss. Conversely, the roughness surface shows its nature as the diffuse reflection light can be received by the sensor. With regards to coal dust in the measurement environment, fine particles of floating coal dust in the air can lead to the loss of measurement data to some extent, due to scattering of the laser beam. PMID:28590449

Experimental Studies of Nuclear Physics Input for γ -Process Nucleosynthesis

NASA Astrophysics Data System (ADS)

Scholz, Philipp; Heim, Felix; Mayer, Jan; Netterdon, Lars; Zilges, Andreas

The predictions of reaction rates for the γ process in the scope of the Hauser-Feshbach statistical model crucially depend on nuclear physics input-parameters as optical-model potentials (OMP) or γ -ray strength functions. Precise cross-section measurements at astrophysically relevant energies help to constrain adopted models and, therefore, to reduce the uncertainties in the theoretically predicted reaction rates. During the last years, several cross-sections of charged-particle induced reactions on heavy nuclei have been measured at the University of Cologne. Either by means of the in-beam method at the HORUS γ -ray spectrometer or the activation technique using the Cologne Clover Counting Setup, total and partial cross-sections could be used to further constrain different models for nuclear physics input-parameters. It could be shown that modifications on the α -OMP in the case of the 112Sn(α , γ ) reaction also improve the description of the recently measured cross sections of the 108Cd(α , γ ) and 108Cd(α , n) reaction and other reactions as well. Partial cross-sections of the 92Mo(p, γ ) reaction were used to improve the γ -strength function model in 93Tc in the same way as it was done for the 89Y(p, γ ) reaction.

Study of the Integration of the CNU-TS-1 Mobile Tunnel Monitoring System.

PubMed

Du, Liming; Zhong, Ruofei; Sun, Haili; Zhu, Qiang; Zhang, Zhen

2018-02-01

A rapid, precise and automated means for the regular inspection and maintenance of a large number of tunnels is needed. Based on the depth study of the tunnel monitoring method, the CNU-TS-1 mobile tunnel monitoring system (TS1) is developed and presented. It can efficiently obtain the cross-sections that are orthogonal to the tunnel in a dynamic way, and the control measurements that depend on design data are eliminated. By using odometers to locate the cross-sections and correcting the data based on longitudinal joints of tunnel segment lining, the cost of the system has been significantly reduced, and the interval between adjacent cross-sections can reach 1-2 cm when pushed to collect data at a normal walking speed. Meanwhile, the relative deformation of tunnel can be analyzed by selecting cross-sections from original data. Through the measurement of the actual tunnel, the applicability of the system for tunnel deformation detection is verified, and the system is shown to be 15 times more efficient than that of the total station. The simulation experiment of the tunnel deformation indicates that the measurement accuracy of TS1 for cross-sections is 1.1 mm. Compared with the traditional method, TS1 improves the efficiency as well as increases the density of the obtained points.

Defining the Field of Existence of Shrouded Blades in High-Speed Gas Turbines

NASA Astrophysics Data System (ADS)

Belousov, Anatoliy I.; Nazdrachev, Sergeiy V.

2018-01-01

This work provides a method for determining the region of existence of banded blades of gas turbines for aircraft engines based on the analytical evaluation of tensile stresses in specific characteristic sections of the blade. This region is determined by the set of values of the parameter, which forms the law of distribution of the cross-sectional area of the cross-sections along the height of the airfoil. When seven independent parameters (gas-dynamic, structural and strength) are changed, the choice of the best option is proposed at the early design stage. As an example, the influence of the dimension of a turbine on the domain of the existence of banded blades is shown.

Near-Unity Quantum Yields for Intersystem Crossing and Singlet Oxygen Generation in Polymethine-like Molecules: Design and Experimental Realization

DTIC Science & Technology

2010-01-01

Florida, Cocoa , Florida 32922, ^Institute of Organic Chemistry, National Academy of Sciences, Kiev 03094, Ukraine, and #Physics and Optical Engineering...the time evolution of the S-S and T-Tabsorption and their cross sections (σSS and σTT). S-SandT-TESAspectra for SD-S7508are shown inFigure3a. SD-O

Benefits of regular aerobic exercise for executive functioning in healthy populations.

PubMed

Guiney, Hayley; Machado, Liana

2013-02-01

Research suggests that regular aerobic exercise has the potential to improve executive functioning, even in healthy populations. The purpose of this review is to elucidate which components of executive functioning benefit from such exercise in healthy populations. In light of the developmental time course of executive functions, we consider separately children, young adults, and older adults. Data to date from studies of aging provide strong evidence of exercise-linked benefits related to task switching, selective attention, inhibition of prepotent responses, and working memory capacity; furthermore, cross-sectional fitness data suggest that working memory updating could potentially benefit as well. In young adults, working memory updating is the main executive function shown to benefit from regular exercise, but cross-sectional data further suggest that task-switching and post error performance may also benefit. In children, working memory capacity has been shown to benefit, and cross-sectional data suggest potential benefits for selective attention and inhibitory control. Although more research investigating exercise-related benefits for specific components of executive functioning is clearly needed in young adults and children, when considered across the age groups, ample evidence indicates that regular engagement in aerobic exercise can provide a simple means for healthy people to optimize a range of executive functions.

Towards a quantitative, measurement-based estimate of the uncertainty in photon mass attenuation coefficients at radiation therapy energies

NASA Astrophysics Data System (ADS)

Ali, E. S. M.; Spencer, B.; McEwen, M. R.; Rogers, D. W. O.

2015-02-01

In this study, a quantitative estimate is derived for the uncertainty in the XCOM photon mass attenuation coefficients in the energy range of interest to external beam radiation therapy—i.e. 100 keV (orthovoltage) to 25 MeV—using direct comparisons of experimental data against Monte Carlo models and theoretical XCOM data. Two independent datasets are used. The first dataset is from our recent transmission measurements and the corresponding EGSnrc calculations (Ali et al 2012 Med. Phys. 39 5990-6003) for 10-30 MV photon beams from the research linac at the National Research Council Canada. The attenuators are graphite and lead, with a total of 140 data points and an experimental uncertainty of ˜0.5% (k = 1). An optimum energy-independent cross section scaling factor that minimizes the discrepancies between measurements and calculations is used to deduce cross section uncertainty. The second dataset is from the aggregate of cross section measurements in the literature for graphite and lead (49 experiments, 288 data points). The dataset is compared to the sum of the XCOM data plus the IAEA photonuclear data. Again, an optimum energy-independent cross section scaling factor is used to deduce the cross section uncertainty. Using the average result from the two datasets, the energy-independent cross section uncertainty estimate is 0.5% (68% confidence) and 0.7% (95% confidence). The potential for energy-dependent errors is discussed. Photon cross section uncertainty is shown to be smaller than the current qualitative ‘envelope of uncertainty’ of the order of 1-2%, as given by Hubbell (1999 Phys. Med. Biol 44 R1-22).

Quest for consistent modelling of statistical decay of the compound nucleus

NASA Astrophysics Data System (ADS)

Banerjee, Tathagata; Nath, S.; Pal, Santanu

2018-01-01

A statistical model description of heavy ion induced fusion-fission reactions is presented where shell effects, collective enhancement of level density, tilting away effect of compound nuclear spin and dissipation are included. It is shown that the inclusion of all these effects provides a consistent picture of fission where fission hindrance is required to explain the experimental values of both pre-scission neutron multiplicities and evaporation residue cross-sections in contrast to some of the earlier works where a fission hindrance is required for pre-scission neutrons but a fission enhancement for evaporation residue cross-sections.

A radiologic correlation with the basic functional neuroanatomy of the brain.

PubMed

Bilicka, Z; Liska, M; Bluska, P; Bilicky, J

2014-01-01

Primary cortical areas for motor, sensory and sensitive functions are localized in certain areas of the brain cortex. In clinical practice, cross sectional imaging (computer tomography and magnetic resonance) is wildy used for diagnostics purpose, treatment planning and follow up of the patients. Accurate orientation in brain structures is necessary for the evaluation of radiological images. There are numerable landmark signs, which can be used for precise identification of important brain structures. In this review article, the mostly used anatomical landmarks are described and shown on the cross sectional images (magnetic resonance imaging) (Fig. 14, Ref. 25).

A coincidence study of electron and positron impact ionization of Ar (3p) at 1 keV

NASA Astrophysics Data System (ADS)

Campeanu, Radu I.; Walters, James H. R.; Whelan, Colm T.

2015-10-01

Distorted-wave calculations of the triple differential cross section (TDCS) are presented for electron and positron impact ionization of Ar(3p) in coplanar asymmetric geometry at an impact energy of 1 keV and are compared with a recent experiment. The experiment indicates that the positron TDCS is generally larger than the equivalent electron TDCS. It is shown that the magnitude of the TDCS is extremely sensitive to the energy of the ejected electron and that only when the cross section is averaged over energy do we get a reasonable agreement with experiment.

Two-photon production of leptons at hadron colliders in semielastic and elastic cases

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

Manko, A. Yu., E-mail: andrej.j.manko@gmail.com; Shulyakovsky, R. G., E-mail: shul@ifanbel.bas-net.by, E-mail: shulyakovsky@iaph.bas-net.by

The mechanism of two-photon dilepton production is studied in the equivalent-photon (Weizsäcker–Williams) approximation. This approximation is shown to describe well experimental data from hadron accelerators. The respective total and differential cross sections were obtained for the LHC and for the Tevatron collider at various energies of colliding hadrons. The differential cross sections were studied versus the dilepton invariant mass, transverse momentum, and emission angle in the reference frame comoving with the center of mass of colliding hadrons. The cases of semielastic and inelastic collisions were examined.

Merging first principle structure studies and few-body reaction formalism

NASA Astrophysics Data System (ADS)

Crespo, R.; Cravo, E.; Arriaga, A.; Wiringa, R.; Deltuva, A.; Diego, R.

2018-02-01

Calculations for nucleon knockout from a 7Li beam due to the collision with a proton target at 400 MeV/u are shown based on ab initio Quantum Monte Carlo (QMC) and conventional shell-model nuclear structure approaches to describe the relative motion between the knockout particle and the heavy fragment of the projectile. Structure effects on the total cross section are shown.

A probabilistic methodology for radar cross section prediction in conceptual aircraft design

NASA Astrophysics Data System (ADS)

Hines, Nathan Robert

System effectiveness has increasingly become the prime metric for the evaluation of military aircraft. As such, it is the decision maker's/designer's goal to maximize system effectiveness. Industry and government research documents indicate that all future military aircraft will incorporate signature reduction as an attempt to improve system effectiveness and reduce the cost of attrition. Today's operating environments demand low observable aircraft which are able to reliably take out valuable, time critical targets. Thus it is desirable to be able to design vehicles that are balanced for increased effectiveness. Previous studies have shown that shaping of the vehicle is one of the most important contributors to radar cross section, a measure of radar signature, and must be considered from the very beginning of the design process. Radar cross section estimation should be incorporated into conceptual design to develop more capable systems. This research strives to meet these needs by developing a conceptual design tool that predicts radar cross section for parametric geometries. This tool predicts the absolute radar cross section of the vehicle as well as the impact of geometry changes, allowing for the simultaneous tradeoff of the aerodynamic, performance, and cost characteristics of the vehicle with the radar cross section. Furthermore, this tool can be linked to a campaign theater analysis code to demonstrate the changes in system and system of system effectiveness due to changes in aircraft geometry. A general methodology was developed and implemented and sample computer codes applied to prototype the proposed process. Studies utilizing this radar cross section tool were subsequently performed to demonstrate the capabilities of this method and show the impact that various inputs have on the outputs of these models. The F/A-18 aircraft configuration was chosen as a case study vehicle to perform a design space exercise and to investigate the relative impact of shaping parameters on radar cross section. Finally, two unique low observable configurations were analyzed to examine the impact of shaping for stealthiness.

Effect of the Mott cross section on the determination of the charge of ultraheavy cosmic rays from emulsion tracks

NASA Technical Reports Server (NTRS)

Eby, P. B.; Morgan, S. H.; Parnell, T. A.

1978-01-01

Energy deposition due to secondary electrons is calculated as a function of distance from the axis of the track of a heavy ion. The calculation incorporates the empirical formulas of Kobetich and Katz (1968) for delta-ray energy dissipation. Both the Mott and Born-approximation expressions for the delta-ray energy distributions are used, and the results are compared. The energy deposition projected along a line perpendicular to the track is also calculated. These results are used to estimate the effect that the use of the Mott cross section would have in the interpretation of photometric measurements on emulsion tracks of trans-iron cosmic-ray particles. It is shown that the use of 50 keV as a characteristic track-formation electron energy to estimate the effect of the Mott cross section systematically overestimates charge as derived from emulsions for Z greater than 20.

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

Dzhilavyan, L. Z., E-mail: dzhil@cpc.inr.ac.ru

The cross section for the reaction {sup 115}In(γ, γ′){sub 115m}In was measured for photon energies in the range of E{sub γ} ≅ 4–46 MeV. The parameters of the peak in this cross section near the threshold for the reaction {sup 115}In(γ, n), (E{sub γ}){sub (γ,n)}{sup thr}, were refined. It is shown that, in the cross section for the reaction {sup 115}In(γ, γ′){sup 115m}In at Eγ ∼ 27 MeV, there is no second peak for which δ{sub II}{sup int} would exceed about 0.2δ{sub I}{sup int} for the peak at E{sub γ} ∼ (E{sub γ}){sub (γ,n)}{sup thr}. The possibility of employing thismore » reaction both in studying photonuclear reaction physics and in monitoring bremsstrahlung photons in gamma-activation studies was examined.« less

Vortex breakdown in closed containers with polygonal cross sections

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

Naumov, I. V., E-mail: naumov@itp.nsc.ru; Dvoynishnikov, S. V.; Kabardin, I. K.

2015-12-15

The vortex breakdown bubble in the confined flow generated by a rotating lid in closed containers with polygonal cross sections was analysed both experimentally and numerically for the height/radius aspect ratio equal to 2. The stagnation point locations of the breakdown bubble emergence and the corresponding Reynolds number were determined experimentally and in addition computed numerically by STAR-CCM+ CFD software for square, pentagonal, hexagonal, and octagonal cross section configurations. The flow pattern and the velocity were observed and measured by combining the seeding particle visualization and the temporal accuracy of laser Doppler anemometry. The vortex breakdown size and position onmore » the container axis were determined for Reynolds numbers, ranging from 1450 to 2400. The obtained results were compared with the flow structure in the closed container of cubical and cylindrical configurations. It is shown that the measured evolution of steady vortex breakdown is in close agreement with the numerical results.« less

Measurement of the absolute differential cross section of proton–proton elastic scattering at small angles

DOE PAGES

Mchedlishvili, D.; Chiladze, D.; Dymov, S.; ...

2016-02-03

The differential cross section for proton-proton elastic scattering has been measured at a beam kinetic energy of 1.0 GeV and in 200 MeV steps from 1.6 to 2.8 GeV for centre-of-mass angles in the range from 12°-16° to 25°-30°, depending on the energy. A precision in the overall normalisation of typically 3% was achieved by studying the energy losses of the circulating beam of the COSY storage ring as it passed repeatedly through the windowless hydrogen target of the ANKE magnetic spectrometer. It is shown that the data have a significant impact upon the results of a partial wave analysis.more » Furthermore, after extrapolating the differential cross sections to the forward direction, the results are broadly compatible with the predictions of forward dispersion relations.« less

Effects of Differing Energy Dependences in Three Level-Density Models on Calculated Cross Sections

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

Fu, C.Y.

2000-07-15

Three level-density formalisms commonly used for cross-section calculations are examined. Residual nuclides in neutron interaction with {sup 58}Ni are chosen to quantify the well-known differences in the energy dependences of the three formalisms. Level-density parameters for the Gilbert and Cameron model are determined from experimental information. Parameters for the back-shifted Fermi-gas and generalized superfluid models are obtained by fitting their level densities at two selected energies for each nuclide to those of the Gilbert and Cameron model, forcing the level densities of the three models to be as close as physically allowed. The remaining differences are in their energy dependencesmore » that, it is shown, can change the calculated cross sections and particle emission spectra significantly, in some cases or energy ranges by a factor of 2.« less

extrap: Software to assist the selection of extrapolation methods for moving-boat ADCP streamflow measurements

USGS Publications Warehouse

Mueller, David S.

2013-01-01

profiles from the entire cross section and multiple transects to determine a mean profile for the measurement. The use of an exponent derived from normalized data from the entire cross section is shown to be valid for application of the power velocity distribution law in the computation of the unmeasured discharge in a cross section. Selected statistics are combined with empirically derived criteria to automatically select the appropriate extrapolation methods. A graphical user interface (GUI) provides the user tools to visually evaluate the automatically selected extrapolation methods and manually change them, as necessary. The sensitivity of the total discharge to available extrapolation methods is presented in the GUI. Use of extrap by field hydrographers has demonstrated that extrap is a more accurate and efficient method of determining the appropriate extrapolation methods compared with tools currently (2012) provided in the ADCP manufacturers’ software.

Stopping cross sections of He + ions in bismuth

NASA Astrophysics Data System (ADS)

Kuldeep; Jain, Animesh K.

1985-06-01

The stopping cross sections, ɛ( E), of He + ions in bismuth have been measured by Rutherford backscattering spectrometry (RBS) at incident energies ranging from E = 1.6-3.4 MeV. The energy loss of He + ions and thicknesses of the bismuth films deposited on aluminium substrates were determined from the RBS spectra at each energy for scattering angles of 130° and 165°. The film thicknesses of some of the samples were also measured by weighing and the results compared with those from RBS. Parameters for energy dependence of stopping cross section in the Varelas-Biersack interpolation formula have been obtained for bismuth from a fit to all the available experimental data. Accuracy of our method based on RBS is demonstrated by measurements on copper, for which ɛ( E) is already well studied. It is also shown that reliable ɛ( E) values may be obtained even on samples with non-uniform film thickness.

Reaction production + AMS: An alternative method to study low energy reactions. 26Al as a test case

NASA Astrophysics Data System (ADS)

Acosta, L.; Araujo-Escalona, V.; Chávez, E.; Andrade, E.; Barrón-Palos, L.; Favela, F.; Flores, M. A.; García-Ramírez, J.; Huerta, A.; de Lucio, O.; Méndez-García, C.; Ortiz, M. E.; Padilla, S.; Sánchez-Benítez, A. M.; Santa Rita, P.; Solís, C.

2018-01-01

Considering the importance of the 26Al nuclei in Astrophysics, in this work, preliminary results regarding a campaign of measurements related with this radioisotope production, are presented. We have taken advantage of two different facilities: first, the radio-nucleus is produced by means of irradiation of targets selected in correlation with particular reactions; once the enrichment with 26Al was made, the targets are analyzed in an AMS machine to obtain the concentration of 26Al produced during the irradiation. With this off-line method, it is possible to measure acceptable small cross sections of a selected low energy reaction. In this work, our preliminary results for three different energies of 28Si(d,α)26Al reaction cross sections are shown, as well as our first considerations to commence with measurements of 25Mg(p,γ)26Al reaction cross sections below 1 MeV.

DØ Results on Diphoton Direct Production and Photon + b and c Jet Production

NASA Astrophysics Data System (ADS)

Sawyer, Lee

2013-11-01

In this note we present measurements of the direct photon pair production cross sections using 8.5 fb-1 of data collected with the DØ detector at the Fermilab Tevatron pmathop plimits^ collider at √s = 1.96 TeV. The results are shown as differential distributions with respect to the photon pair mass, pair transverse momentum, azimuthal angle, and polar scattering angle in the Collins-Soper frame. We also present measurements of the differential cross section dσ/dpTγ for the inclusive production of a photon in association with a b- or c-quark jet. The results are based on 8.7 fb-1 of data, and the measured cross sections are compared with next-to-leading order perturbative QCD calculations using different sets of parton distribution functions as well as to predictions based on the kT-factorization QCD approach, and those from various Monte Carlo event generators.

Temperature compensated cuts in LGT crystal microresonators using length extensional mode.

PubMed

Douchet, Gabrielle; Sthal, Fabrice; Bigler, Emmanuel; Bourquin, Roger

2009-02-01

In this letter, experimental investigation of frequency-temperature effects in langatate rectangular cross-section beams are presented. It is shown that a first-order temperature compensated cut exists for the first vibrating mode of length extension.

CFD simulations of the flow control performance applied for inlet of low drag high-bypass turbofan engine at cross flow regimes

NASA Astrophysics Data System (ADS)

Kursakov, I. A.; Kazhan, E. V.; Lysenkov, A. V.; Savelyev, A. A.

2016-10-01

Paper describes the optimization procedure for low cruise drag inlet of high-bypass ratio turbofan engine (HBRE). The critical cross-flow velocity when the flow separation on the lee side of the inlet channel occurs is determined. The effciency of different flow control devices used to improve the flow parameters at inlet section cross flow regime is analyzed. Boundary layer suction, bypass slot and vortex generators are considered. It is shown that flow control devices enlarge the stability range of inlet performance at cross flow regimes.

Average Cross-Sectional Area of DebriSat Fragments Using Volumetrically Constructed 3D Representations

NASA Technical Reports Server (NTRS)

Scruggs, T.; Moraguez, M.; Patankar, K.; Fitz-Coy, N.; Liou, J.-C.; Sorge, M.; Huynh, T.

2016-01-01

Debris fragments from the hypervelocity impact testing of DebriSat are being collected and characterized for use in updating existing satellite breakup models. One of the key parameters utilized in these models is the ballistic coefficient of the fragment which is directly related to its area-to-mass ratio. However, since the attitude of fragments varies during their orbital lifetime, it is customary to use the average cross-sectional area in the calculation of the area-to-mass ratio. The average cross-sectional area is defined as the average of the projected surface areas perpendicular to the direction of motion and has been shown to be equal to one-fourth of the total surface area of a convex object. Unfortunately, numerous fragments obtained from the DebriSat experiment show significant concavity (i.e., shadowing) and thus we have explored alternate methods for computing the average cross-sectional area of the fragments. An imaging system based on the volumetric reconstruction of a 3D object from multiple 2D photographs of the object was developed for use in determining the size characteristic (i.e., characteristics length) of the DebriSat fragments. For each fragment, the imaging system generates N number of images from varied azimuth and elevation angles and processes them using a space-carving algorithm to construct a 3D point cloud of the fragment. This paper describes two approaches for calculating the average cross-sectional area of debris fragments based on the 3D imager. Approach A utilizes the constructed 3D object to generate equally distributed cross-sectional area projections and then averages them to determine the average cross-sectional area. Approach B utilizes a weighted average of the area of the 2D photographs to directly compute the average cross-sectional area. A comparison of the accuracy and computational needs of each approach is described as well as preliminary results of an analysis to determine the "optimal" number of images needed for the 3D imager to accurately measure the average cross sectional area of objects with known dimensions.

Long-range dynamic polarization potentials for 11Be projectiles on 64Zn

NASA Astrophysics Data System (ADS)

So, W. Y.; Kim, K. S.; Choi, K. S.; Cheoun, Myung-Ki

2015-07-01

We investigate the effects of the long-range dynamic polarization (LRDP) potential, which consists of the Coulomb dipole excitation (CDE) potential and the long-range nuclear (LRN) potential, for the 11Be projectile on 64Zn. To study these effects, we perform a χ2 analysis of an optical model including the LRDP potential as well as a conventional short-range nuclear (SRN) potential. To take these effects into account, we argue that both the CDE and LRN potentials are essential to explaining the experimental values of PE, which is the ratio of the elastic scattering cross section to the Rutherford cross section. The Coulomb and nuclear parts of the LRDP potential are found to contribute to a strong absorption effect. Strong absorption occurs because the real part of the CDE and LRN potentials lowers the barrier, and the imaginary part of the CDE and LRN potentials removes the flux from the elastic channel in the 11Be+64Zn system. Finally, we extract the total reaction cross section σR including the inelastic, breakup, and fusion cross sections. The contribution of the inelastic scattering by the first excited state at ɛx1 st=0.32 MeV (1 /2-) is found to be relatively large and cannot be ignored. In addition, our results are shown to agree quite well with the experimental breakup reaction cross section by using a fairly large radius parameter.

On vertical profile of ozone at Syowa

NASA Technical Reports Server (NTRS)

Chubachi, Shigeru

1994-01-01

The difference in the vertical ozone profile at Syowa between 1966-1981 and 1982-1988 is shown. The month-height cross section of the slope of the linear regressions between ozone partial pressure and 100-mb temperature is also shown. The vertically integrated values of the slopes are in close agreement with the slopes calculated by linear regression of Dobson total ozone on 100-mb temperature in the period of 1982-1988.

Tin particle size measurements in high explosively driven shockwave experiments using Mie scattering method

NASA Astrophysics Data System (ADS)

Monfared, Shabnam; Buttler, William; Schauer, Martin; Lalone, Brandon; Pack, Cora; Stevens, Gerald; Stone, Joseph; Special Technologies Laboratory Collaboration; Los Alamos National Laboratory Team

2014-03-01

Los Alamos National Laboratory is actively engaged in the study of material failure physics to support the hydrodynamic models development, where an important failure mechanism of explosively shocked metals causes mass ejection from the backside of a shocked surface with surface perturbations. Ejecta models are in development for this situation. Our past work has clearly shown that the total ejected mass and mass-velocity distribution sensitively link to the wavelength and amplitude of these perturbations. While we have had success developing ejecta mass and mass-velocity models, we need to better understand the size and size-velocity distributions of the ejected mass. To support size measurements we have developed a dynamic Mie scattering diagnostic based on a CW laser that permits measurement of the forward attenuation cross-section combined with a dynamic mass-density and mass-velocity distribution, as well as a measurement of the forward scattering cross-section at 12 angles (5- 32.5 degrees) in increments of 2.5 degrees. We compare size distribution followed from Beers law with attenuation cross-section and mass measurement to the dynamic size distribution determined from scattering cross-section alone. We report results from our first quality experiments.

First measurement of coherent ϕ -meson photoproduction from 4He near threshold

NASA Astrophysics Data System (ADS)

Hiraiwa, T.; Yosoi, M.; Niiyama, M.; Morino, Y.; Nakatsugawa, Y.; Sumihama, M.; Ahn, D. S.; Ahn, J. K.; Chang, W. C.; Chen, J. Y.; Daté, S.; Fujimura, H.; Fukui, S.; Hicks, K.; Hotta, T.; Hwang, S. H.; Ishikawa, T.; Kato, Y.; Kawai, H.; Kohri, H.; Kon, Y.; Lin, P. J.; Maeda, Y.; Miyabe, M.; Mizutani, K.; Muramatsu, N.; Nakano, T.; Nozawa, Y.; Ohashi, Y.; Ohta, T.; Oka, M.; Rangacharyulu, C.; Ryu, S. Y.; Saito, T.; Sawada, T.; Shimizu, H.; Strokovsky, E. A.; Sugaya, Y.; Suzuki, K.; Tokiyasu, A. O.; Tomioka, T.; Tsunemi, T.; Uchida, M.; Yorita, T.; LEPS Collaboration

2018-03-01

The differential cross sections and decay angular distributions for coherent ϕ -meson photoproduction from helium-4 are measured for the first time at forward angles with linearly polarized photons in the energy range Eγ=1.685 -2.385 GeV . Thanks to the target with spin-parity JP=0+ , unnatural-parity exchanges are absent, and thus natural-parity exchanges can be investigated clearly. The decay asymmetry with respect to photon polarization is shown to be very close to the maximal value. This ensures the strong dominance (>94 %) of natural-parity exchanges in this reaction. To evaluate the contribution from natural-parity exchanges to the forward cross section (θ =0∘ ) for the γ p →ϕ p reaction near threshold, the energy dependence of the forward cross section (θ =0∘ ) for the γ 4He →ϕ 4He reaction is analyzed. The comparison to γ p →ϕ p data suggests that enhancement of the forward cross section arising from natural-parity exchanges and/or destructive interference between natural-parity and unnatural-parity exchanges is needed in the γ p →ϕ p reaction near threshold.

Measurement of double-differential cross sections for top quark pair production in pp collisions at √{s} = 8 {TeV} and impact on parton distribution functions

NASA Astrophysics Data System (ADS)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; König, A.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rad, N.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Strauss, J.; Waltenberger, W.; Wulz, C.-E.; Dvornikov, O.; Makarenko, V.; Mossolov, V.; Suarez Gonzalez, J.; Zykunov, V.; Shumeiko, N.; Alderweireldt, S.; De Wolf, E. A.; Janssen, X.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; De Bruyn, I.; Deroover, K.; Lowette, S.; Moortgat, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Skovpen, K.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Brun, H.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Léonard, A.; Luetic, J.; Maerschalk, T.; Marinov, A.; Randle-conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Vannerom, D.; Yonamine, R.; Zenoni, F.; Zhang, F.; Cornelis, T.; Dobur, D.; Fagot, A.; Gul, M.; Khvastunov, I.; Poyraz, D.; Salva, S.; Schöfbeck, R.; Tytgat, M.; Van Driessche, W.; Yazgan, E.; Zaganidis, N.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Jafari, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Chagas, E. Belchior Batista Das; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; De Oliveira Martins, C.; De Souza, S. Fonseca; Guativa, L. M. Huertas; Malbouisson, H.; Matos Figueiredo, D.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Torres Da Silva De Araujo, F.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Moon, C. S.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Cheng, T.; Jiang, C. H.; Leggat, D.; Liu, Z.; Romeo, F.; Ruan, M.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Zhang, H.; Zhao, J.; Ban, Y.; Chen, G.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Sculac, T.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Mesic, B.; Susa, T.; Ather, M. W.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Finger, M.; Finger, M.; Carrera Jarrin, E.; Ellithi Kamel, A.; Mahmoud, M. A.; Radi, A.; Kadastik, M.; Perrini, L.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Ghosh, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Kucher, I.; Locci, E.; Machet, M.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Abdulsalam, A.; Antropov, I.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Chapon, E.; Charlot, C.; Davignon, O.; Granier de Cassagnac, R.; Jo, M.; Lisniak, S.; Miné, P.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Pigard, P.; Regnard, S.; Salerno, R.; Sirois, Y.; Stahl Leiton, A. G.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Zghiche, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Bihan, A.-C. Le; Van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Carrillo Montoya, C. A.; Chierici, R.; Contardo, D.; Courbon, B.; Depasse, P.; El Mamouni, H.; Fay, J.; Finco, L.; Gascon, S.; Gouzevitch, M.; Grenier, G.; Ille, B.; Lagarde, F.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Popov, A.; Sordini, V.; Vander Donckt, M.; Verdier, P.; Viret, S.; Khvedelidze, A.; Lomidze, D.; Autermann, C.; Beranek, S.; Feld, L.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Preuten, M.; Schomakers, C.; Schulz, J.; Verlage, T.; Albert, A.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hamer, M.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Olschewski, M.; Padeken, K.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Cherepanov, V.; Flügge, G.; Kargoll, B.; Kress, T.; Künsken, A.; Lingemann, J.; Müller, T.; Nehrkorn, A.; Nowack, A.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Arndt, T.; Asawatangtrakuldee, C.; Beernaert, K.; Behnke, O.; Behrens, U.; Bin Anuar, A. A.; Borras, K.; Campbell, A.; Connor, P.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Eren, E.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Grados Luyando, J. M.; Grohsjean, A.; Gunnellini, P.; Harb, A.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Karacheban, O.; Kasemann, M.; Keaveney, J.; Kleinwort, C.; Korol, I.; Krücker, D.; Lange, W.; Lelek, A.; Lenz, T.; Leonard, J.; Lipka, K.; Lobanov, A.; Lohmann, W.; Mankel, R.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Roland, B.; Sahin, M. Ö.; Saxena, P.; Schoerner-Sadenius, T.; Spannagel, S.; Stefaniuk, N.; Van Onsem, G. P.; Walsh, R.; Wissing, C.; Zenaiev, O.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Dreyer, T.; Garutti, E.; Gonzalez, D.; Haller, J.; Hoffmann, M.; Junkes, A.; Klanner, R.; Kogler, R.; Kovalchuk, N.; Kurz, S.; Lapsien, T.; Marchesini, I.; Marconi, D.; Meyer, M.; Niedziela, M.; Nowatschin, D.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Scharf, C.; Schleper, P.; Schmidt, A.; Schumann, S.; Schwandt, J.; Sonneveld, J.; Stadie, H.; Steinbrück, G.; Stober, F. M.; Stöver, M.; Tholen, H.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Vormwald, B.; Akbiyik, M.; Barth, C.; Baur, S.; Baus, C.; Berger, J.; Butz, E.; Caspart, R.; Chwalek, T.; Colombo, F.; De Boer, W.; Dierlamm, A.; Fink, S.; Freund, B.; Friese, R.; Giffels, M.; Gilbert, A.; Goldenzweig, P.; Haitz, D.; Hartmann, F.; Heindl, S. M.; Husemann, U.; Kassel, F.; Katkov, I.; Kudella, S.; Mildner, H.; Mozer, M. U.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Röcker, S.; Roscher, F.; Schröder, M.; Shvetsov, I.; Sieber, G.; Simonis, H. J.; Ulrich, R.; Wayand, S.; Weber, M.; Weiler, T.; Williamson, S.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Topsis-Giotis, I.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Tziaferi, E.; Kousouris, K.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Loukas, N.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Filipovic, N.; Pasztor, G.; Bencze, G.; Hajdu, C.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Karancsi, J.; Makovec, A.; Molnar, J.; Szillasi, Z.; Bartók, M.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Komaragiri, J. R.; Bahinipati, S.; Bhowmik, S.; Choudhury, S.; Mal, P.; Mandal, K.; Nayak, A.; Sahoo, D. K.; Sahoo, N.; Swain, S. K.; Bansal, S.; Beri, S. B.; Bhatnagar, V.; Chawla, R.; Bhawandeep, U.; Kalsi, A. K.; Kaur, A.; Kaur, M.; Kumar, R.; Kumari, P.; Mehta, A.; Mittal, M.; Singh, J. B.; Walia, G.; Kumar, Ashok; Bhardwaj, A.; Choudhary, B. C.; Garg, R. B.; Keshri, S.; Kumar, A.; Malhotra, S.; Naimuddin, M.; Ranjan, K.; Sharma, R.; Sharma, V.; Bhattacharya, R.; Bhattacharya, S.; Chatterjee, K.; Dey, S.; Dutt, S.; Dutta, S.; Ghosh, S.; Majumdar, N.; Modak, A.; Mondal, K.; Mukhopadhyay, S.; Nandan, S.; Purohit, A.; Roy, A.; Roy, D.; Roy Chowdhury, S.; Sarkar, S.; Sharan, M.; Thakur, S.; Behera, P. K.; Chudasama, R.; Dutta, D.; Jha, V.; Kumar, V.; Mohanty, A. K.; Netrakanti, P. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Dugad, S.; Kole, G.; Mahakud, B.; Mitra, S.; Mohanty, G. B.; Parida, B.; Sur, N.; Sutar, B.; Banerjee, S.; Dewanjee, R. K.; Ganguly, S.; Guchait, M.; Jain, Sa.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Sarkar, T.; Wickramage, N.; Chauhan, S.; Dube, S.; Hegde, V.; Kapoor, A.; Kothekar, K.; Pandey, S.; Rane, A.; Sharma, S.; Chenarani, S.; Eskandari Tadavani, E.; Etesami, S. M.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Rezaei Hosseinabadi, F.; Safarzadeh, B.; Zeinali, M.; Felcini, M.; Grunewald, M.; Abbrescia, M.; Calabria, C.; Caputo, C.; Colaleo, A.; Creanza, D.; Cristella, L.; De Filippis, N.; De Palma, M.; Fiore, L.; Iaselli, G.; Maggi, G.; Maggi, M.; Miniello, G.; My, S.; Nuzzo, S.; Pompili, A.; Pugliese, G.; Radogna, R.; Ranieri, A.; Selvaggi, G.; Sharma, A.; Silvestris, L.; Venditti, R.; Verwilligen, P.; Abbiendi, G.; Battilana, C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Chhibra, S. S.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Montanari, A.; Navarria, F. L.; Perrotta, A.; Rossi, A. M.; Rovelli, T.; Siroli, G. P.; Tosi, N.; Albergo, S.; Costa, S.; Di Mattia, A.; Giordano, F.; Potenza, R.; Tricomi, A.; Tuve, C.; Barbagli, G.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Lenzi, P.; Meschini, M.; Paoletti, S.; Russo, L.; Sguazzoni, G.; Strom, D.; Viliani, L.; Benussi, L.; Bianco, S.; Fabbri, F.; Piccolo, D.; Primavera, F.; Calvelli, V.; Ferro, F.; Monge, M. R.; Robutti, E.; Tosi, S.; Brianza, L.; Brivio, F.; Ciriolo, V.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Ghezzi, A.; Govoni, P.; Malberti, M.; Malvezzi, S.; Manzoni, R. A.; Menasce, D.; Moroni, L.; Paganoni, M.; Pedrini, D.; Pigazzini, S.; Ragazzi, S.; Tabarelli de Fatis, T.; Buontempo, S.; Cavallo, N.; De Nardo, G.; Di Guida, S.; Esposito, M.; Fabozzi, F.; Fienga, F.; Iorio, A. O. M.; Lanza, G.; Lista, L.; Meola, S.; Paolucci, P.; Sciacca, C.; Thyssen, F.; Azzi, P.; Bacchetta, N.; Benato, L.; Bisello, D.; Boletti, A.; Carlin, R.; Antunes De Oliveira, A. Carvalho; Checchia, P.; Dall'Osso, M.; De Castro Manzano, P.; Dorigo, T.; Dosselli, U.; Gasparini, U.; Gonella, F.; Lacaprara, S.; Margoni, M.; Meneguzzo, A. T.; Pazzini, J.; Pozzobon, N.; Ronchese, P.; Rossin, R.; Simonetto, F.; Torassa, E.; Ventura, S.; Zanetti, M.; Zotto, P.; Braghieri, A.; Fallavollita, F.; Magnani, A.; Montagna, P.; Ratti, S. P.; Re, V.; Ressegotti, M.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Alunni Solestizi, L.; Bilei, G. M.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Leonardi, R.; Mantovani, G.; Mariani, V.; Menichelli, M.; Saha, A.; Santocchia, A.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Bernardini, J.; Boccali, T.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Fedi, G.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. 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A.; Shoaib, M.; Waqas, M.; Bialkowska, H.; Bluj, M.; Boimska, B.; Frueboes, T.; Górski, M.; Kazana, M.; Nawrocki, K.; Romanowska-Rybinska, K.; Szleper, M.; Zalewski, P.; Bunkowski, K.; Byszuk, A.; Doroba, K.; Kalinowski, A.; Konecki, M.; Krolikowski, J.; Misiura, M.; Olszewski, M.; Pyskir, A.; Walczak, M.; Bargassa, P.; Beirão Da Cruz E Silva, C.; Calpas, B.; Di Francesco, A.; Faccioli, P.; Gallinaro, M.; Hollar, J.; Leonardo, N.; Lloret Iglesias, L.; Nemallapudi, M. 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P.; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Navarro De Martino, E.; Pérez-Calero Yzquierdo, A.; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; de Trocóniz, J. F.; Missiroli, M.; Moran, D.; Cuevas, J.; Erice, C.; Fernandez Menendez, J.; Gonzalez Caballero, I.; González Fernández, J. R.; Palencia Cortezon, E.; Sanchez Cruz, S.; Suárez Andrés, I.; Vischia, P.; Vizan Garcia, J. M.; Cabrillo, I. J.; Calderon, A.; Curras, E.; Fernandez, M.; Garcia-Ferrero, J.; Gomez, G.; Lopez Virto, A.; Marco, J.; Martinez Rivero, C.; Matorras, F.; Piedra Gomez, J.; Rodrigo, T.; Ruiz-Jimeno, A.; Scodellaro, L.; Trevisani, N.; Vila, I.; Vilar Cortabitarte, R.; Abbaneo, D.; Auffray, E.; Auzinger, G.; Baillon, P.; Ball, A. 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A.; Mersi, S.; Meschi, E.; Milenovic, P.; Moortgat, F.; Morovic, S.; Mulders, M.; Neugebauer, H.; Orfanelli, S.; Orsini, L.; Pape, L.; Perez, E.; Peruzzi, M.; Petrilli, A.; Petrucciani, G.; Pfeiffer, A.; Pierini, M.; Racz, A.; Reis, T.; Rolandi, G.; Rovere, M.; Sakulin, H.; Sauvan, J. B.; Schäfer, C.; Schwick, C.; Seidel, M.; Sharma, A.; Silva, P.; Sphicas, P.; Steggemann, J.; Stoye, M.; Takahashi, Y.; Tosi, M.; Treille, D.; Triossi, A.; Tsirou, A.; Veckalns, V.; Veres, G. I.; Verweij, M.; Wardle, N.; Wöhri, H. K.; Zagozdzinska, A.; Zeuner, W. D.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; Kotlinski, D.; Langenegger, U.; Rohe, T.; Wiederkehr, S. A.; Bachmair, F.; Bäni, L.; Bianchini, L.; Casal, B.; Dissertori, G.; Dittmar, M.; Donegà, M.; Grab, C.; Heidegger, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Meinhard, M. T.; Meister, D.; Micheli, F.; Musella, P.; Nessi-Tedaldi, F.; Pandolfi, F.; Pata, J.; Pauss, F.; Perrin, G.; Perrozzi, L.; Quittnat, M.; Rossini, M.; Schönenberger, M.; Starodumov, A.; Tavolaro, V. R.; Theofilatos, K.; Wallny, R.; Aarrestad, T. K.; Amsler, C.; Caminada, L.; Canelli, M. F.; De Cosa, A.; Donato, S.; Galloni, C.; Hinzmann, A.; Hreus, T.; Kilminster, B.; Ngadiuba, J.; Pinna, D.; Rauco, G.; Robmann, P.; Salerno, D.; Seitz, C.; Yang, Y.; Zucchetta, A.; Candelise, V.; Doan, T. H.; Jain, Sh.; Khurana, R.; Konyushikhin, M.; Kuo, C. M.; Lin, W.; Pozdnyakov, A.; Yu, S. S.; Kumar, Arun; Chang, P.; Chang, Y. H.; Chao, Y.; Chen, K. F.; Chen, P. H.; Fiori, F.; Hou, W.-S.; Hsiung, Y.; Liu, Y. F.; Lu, R.-S.; Miñano Moya, M.; Paganis, E.; Psallidas, A.; Tsai, J. F.; Asavapibhop, B.; Singh, G.; Srimanobhas, N.; Suwonjandee, N.; Adiguzel, A.; Boran, F.; Cerci, S.; Damarseckin, S.; Demiroglu, Z. S.; Dozen, C.; Dumanoglu, I.; Girgis, S.; Gokbulut, G.; Guler, Y.; Hos, I.; Kangal, E. 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R.; Williams, T.; Baber, M.; Bainbridge, R.; Buchmuller, O.; Bundock, A.; Casasso, S.; Citron, M.; Colling, D.; Corpe, L.; Dauncey, P.; Davies, G.; De Wit, A.; Della Negra, M.; Di Maria, R.; Dunne, P.; Elwood, A.; Futyan, D.; Haddad, Y.; Hall, G.; Iles, G.; James, T.; Lane, R.; Laner, C.; Lyons, L.; Magnan, A.-M.; Malik, S.; Mastrolorenzo, L.; Nash, J.; Nikitenko, A.; Pela, J.; Penning, B.; Pesaresi, M.; Raymond, D. M.; Richards, A.; Rose, A.; Scott, E.; Seez, C.; Summers, S.; Tapper, A.; Uchida, K.; Vazquez Acosta, M.; Virdee, T.; Wright, J.; Zenz, S. C.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Borzou, A.; Call, K.; Dittmann, J.; Hatakeyama, K.; Liu, H.; Pastika, N.; Bartek, R.; Dominguez, A.; Buccilli, A.; Cooper, S. I.; Henderson, C.; Rumerio, P.; West, C.; Arcaro, D.; Avetisyan, A.; Bose, T.; Gastler, D.; Rankin, D.; Richardson, C.; Rohlf, J.; Sulak, L.; Zou, D.; Benelli, G.; Cutts, D.; Garabedian, A.; Hakala, J.; Heintz, U.; Hogan, J. M.; Jesus, O.; Kwok, K. H. M.; Laird, E.; Landsberg, G.; Mao, Z.; Narain, M.; Piperov, S.; Sagir, S.; Spencer, E.; Syarif, R.; Breedon, R.; Burns, D.; Calderon De La Barca Sanchez, M.; Chauhan, S.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Flores, C.; Funk, G.; Gardner, M.; Ko, W.; Lander, R.; Mclean, C.; Mulhearn, M.; Pellett, D.; Pilot, J.; Shalhout, S.; Shi, M.; Smith, J.; Squires, M.; Stolp, D.; Tos, K.; Tripathi, M.; Bachtis, M.; Bravo, C.; Cousins, R.; Dasgupta, A.; Florent, A.; Hauser, J.; Ignatenko, M.; Mccoll, N.; Saltzberg, D.; Schnaible, C.; Valuev, V.; Weber, M.; Bouvier, E.; Burt, K.; Clare, R.; Ellison, J.; Gary, J. W.; Ghiasi Shirazi, S. M. A.; Hanson, G.; Heilman, J.; Jandir, P.; Kennedy, E.; Lacroix, F.; Long, O. R.; Olmedo Negrete, M.; Paneva, M. I.; Shrinivas, A.; Si, W.; Wei, H.; Wimpenny, S.; Yates, B. R.; Branson, J. G.; Cerati, G. B.; Cittolin, S.; Derdzinski, M.; Gerosa, R.; Holzner, A.; Klein, D.; Krutelyov, V.; Letts, J.; Macneill, I.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Vartak, A.; Wasserbaech, S.; Welke, C.; Wood, J.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Amin, N.; Bhandari, R.; Bradmiller-Feld, J.; Campagnari, C.; Dishaw, A.; Dutta, V.; Franco Sevilla, M.; George, C.; Golf, F.; Gouskos, L.; Gran, J.; Heller, R.; Incandela, J.; Mullin, S. D.; Ovcharova, A.; Qu, H.; Richman, J.; Stuart, D.; Suarez, I.; Yoo, J.; Anderson, D.; Bendavid, J.; Bornheim, A.; Bunn, J.; Duarte, J.; Lawhorn, J. M.; Mott, A.; Newman, H. B.; Pena, C.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhu, R. Y.; Andrews, M. B.; Ferguson, T.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Weinberg, M.; Cumalat, J. P.; Ford, W. 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M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Cavanaugh, R.; Chen, X.; Evdokimov, O.; Gerber, C. E.; Hangal, D. A.; Hofman, D. J.; Jung, K.; Kamin, J.; Sandoval Gonzalez, I. D.; Trauger, H.; Varelas, N.; Wang, H.; Wu, Z.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; You, C.; Al-bataineh, A.; Baringer, P.; Bean, A.; Boren, S.; Bowen, J.; Castle, J.; Forthomme, L.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Mcbrayer, W.; Murray, M.; Sanders, S.; Stringer, R.; Tapia Takaki, J. 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2017-07-01

Normalized double-differential cross sections for top quark pair (t\\overline{t}) production are measured in pp collisions at a centre-of-mass energy of 8 {TeV} with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7 {fb}^{-1}. The measurement is performed in the dilepton e^{± }μ ^{∓ } final state. The t\\overline{t} cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and t\\overline{t} system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured t\\overline{t} cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution.

Measurement of double-differential cross sections for top quark pair production in pp collisions at [Formula: see text][Formula: see text] and impact on parton distribution functions.

PubMed

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Pollack, B; Schmitt, M H; Sung, K; Trovato, M; Velasco, M; Dev, N; Hildreth, M; Hurtado Anampa, K; Jessop, C; Karmgard, D J; Kellams, N; Lannon, K; Marinelli, N; Meng, F; Mueller, C; Musienko, Y; Planer, M; Reinsvold, A; Ruchti, R; Rupprecht, N; Smith, G; Taroni, S; Wayne, M; Wolf, M; Woodard, A; Alimena, J; Antonelli, L; Bylsma, B; Durkin, L S; Flowers, S; Francis, B; Hart, A; Hill, C; Ji, W; Liu, B; Luo, W; Puigh, D; Winer, B L; Wulsin, H W; Cooperstein, S; Driga, O; Elmer, P; Hardenbrook, J; Hebda, P; Lange, D; Luo, J; Marlow, D; Medvedeva, T; Mei, K; Ojalvo, I; Olsen, J; Palmer, C; Piroué, P; Stickland, D; Svyatkovskiy, A; Tully, C; Malik, S; Barker, A; Barnes, V E; Folgueras, S; Gutay, L; Jha, M K; Jones, M; Jung, A W; Khatiwada, A; Miller, D H; Neumeister, N; Schulte, J F; Shi, X; Sun, J; Wang, F; Xie, W; Parashar, N; Stupak, J; Adair, A; Akgun, B; Chen, Z; Ecklund, K M; Geurts, F J M; Guilbaud, M; Li, W; Michlin, B; Northup, M; Padley, B P; Roberts, J; Rorie, J; Tu, Z; Zabel, J; Betchart, B; Bodek, A; de Barbaro, P; Demina, R; Duh, Y T; Ferbel, T; Galanti, M; Garcia-Bellido, A; Han, J; Hindrichs, O; Khukhunaishvili, A; Lo, K H; Tan, P; Verzetti, M; Agapitos, A; Chou, J P; Gershtein, Y; Gómez Espinosa, T A; Halkiadakis, E; Heindl, M; Hughes, E; Kaplan, S; Kunnawalkam Elayavalli, R; Kyriacou, S; Lath, A; Montalvo, R; Nash, K; Osherson, M; Saka, H; Salur, S; Schnetzer, S; Sheffield, D; Somalwar, S; Stone, R; Thomas, S; Thomassen, P; Walker, M; Delannoy, A G; Foerster, M; Heideman, J; Riley, G; Rose, K; Spanier, S; Thapa, K; Bouhali, O; Celik, A; Dalchenko, M; De Mattia, M; Delgado, A; Dildick, S; Eusebi, R; Gilmore, J; Huang, T; Juska, E; Kamon, T; Mueller, R; Pakhotin, Y; Patel, R; Perloff, A; Perniè, L; Rathjens, D; Safonov, A; Tatarinov, A; Ulmer, K A; Akchurin, N; Damgov, J; De Guio, F; Dragoiu, C; Dudero, P R; Faulkner, J; Gurpinar, E; Kunori, S; Lamichhane, K; Lee, S W; Libeiro, T; Peltola, T; Undleeb, S; Volobouev, I; Wang, Z; Greene, S; Gurrola, A; Janjam, R; Johns, W; Maguire, C; Melo, A; Ni, H; Sheldon, P; Tuo, S; Velkovska, J; Xu, Q; Arenton, M W; Barria, P; Cox, B; Hirosky, R; Ledovskoy, A; Li, H; Neu, C; Sinthuprasith, T; Sun, X; Wang, Y; Wolfe, E; Xia, F; Clarke, C; Harr, R; Karchin, P E; Sturdy, J; Zaleski, S; Belknap, D A; Buchanan, J; Caillol, C; Dasu, S; Dodd, L; Duric, S; Gomber, B; Grothe, M; Herndon, M; Hervé, A; Hussain, U; Klabbers, P; Lanaro, A; Levine, A; Long, K; Loveless, R; Pierro, G A; Polese, G; Ruggles, T; Savin, A; Smith, N; Smith, W H; Taylor, D; Woods, N

2017-01-01

Normalized double-differential cross sections for top quark pair ([Formula: see text]) production are measured in pp collisions at a centre-of-mass energy of 8[Formula: see text] with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7[Formula: see text]. The measurement is performed in the dilepton [Formula: see text] final state. The [Formula: see text] cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and [Formula: see text] system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured [Formula: see text] cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution.

Quasicontinuum γ decay of Zr 91 , 92 : Benchmarking indirect ( n , γ ) cross section measurements for the s process

DOE PAGES

Guttormsen, M.; Goriely, S.; Larsen, A. C.; ...

2017-08-21

Here, nuclear level densities (NLDs) and γ-ray strength functions (γSFs) have been extracted from particle-γ coincidences of the 92Zr(p,p´γ) 92Zr and 92Zr (p,dγ) 91Zr reactions using the Oslo method. The new 91,92Zr γSF data, combined with photonuclear cross sections, cover the whole energy range from Eγ ≈ 1.5 MeV up to the giant dipole resonance at Eγ ≈ 17 MeV. The wide-range γSF data display structures at Eγ ≈ 9.5 MeV, compatible with a superposition of the spin-flip M1 resonance and a pygmy E1 resonance. Furthermore, the γSF shows a minimum at Eγ ≈ 2–3 MeV and an increase atmore » lower γ-ray energies. The experimentally constrained NLDs and γSFs are shown to reproduce known (n,γ) and Maxwellian-averaged cross sections for 91,92Zr using the TALYS reaction code, thus serving as a benchmark for this indirect method of estimating (n,γ) cross sections for Zr isotopes.« less

Photodissociation in the atmosphere of Mars - Impact of high resolution, temperature-dependent CO2 cross-section measurements

NASA Technical Reports Server (NTRS)

Anbar, A. D.; Allen, M.; Nair, H. A.

1993-01-01

We have investigated the impact of high resolution, temperature-dependent CO2 cross-section measurements, reported by Lewis and Carver (1983), on calculations of photodissociation rate coefficients in the Martian atmosphere. We find that the adoption of 50 A intervals for the purpose of computational efficiency results in errors in the calculated values for photodissociation of CO2, H2O, and O2 which are generally not above 10 percent, but as large as 20 percent in some instances. These are acceptably small errors, especially considering the uncertainties introduced by the large temperature dependence of the CO2 cross section. The inclusion of temperature-dependent CO2 cross sections is shown to lead to a decrease in the diurnally averaged rate of CO2 photodissociation as large as 33 percent at some altitudes, and increases of as much as 950 percent and 80 percent in the photodissociation rate coefficients of H2O and O2, respectively. The actual magnitude of the changes depends on the assumptions used to model the CO2 absorption spectrum at temperatures lower than the available measurements, and at wavelengths longward of 1970 A.

Converting point-wise nuclear cross sections to pole representation using regularized vector fitting

NASA Astrophysics Data System (ADS)

Peng, Xingjie; Ducru, Pablo; Liu, Shichang; Forget, Benoit; Liang, Jingang; Smith, Kord

2018-03-01

Direct Doppler broadening of nuclear cross sections in Monte Carlo codes has been widely sought for coupled reactor simulations. One recent approach proposed analytical broadening using a pole representation of the commonly used resonance models and the introduction of a local windowing scheme to improve performance (Hwang, 1987; Forget et al., 2014; Josey et al., 2015, 2016). This pole representation has been achieved in the past by converting resonance parameters in the evaluation nuclear data library into poles and residues. However, cross sections of some isotopes are only provided as point-wise data in ENDF/B-VII.1 library. To convert these isotopes to pole representation, a recent approach has been proposed using the relaxed vector fitting (RVF) algorithm (Gustavsen and Semlyen, 1999; Gustavsen, 2006; Liu et al., 2018). This approach however needs to specify ahead of time the number of poles. This article addresses this issue by adding a poles and residues filtering step to the RVF procedure. This regularized VF (ReV-Fit) algorithm is shown to efficiently converge the poles close to the physical ones, eliminating most of the superfluous poles, and thus enabling the conversion of point-wise nuclear cross sections.

Pressure broadening of the ((dt. mu. )dee)* formation resonances

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

Cohen, J.S.; Leon, M.; Padial, N.T.

1988-12-27

The treatment of ((dt..mu..)dee)* formation at high densities as a pressure broadening process is discussed. Cross sections for collisions of the complex (dt..mu..)dee, and of the D/sub 2/ molecule from which it is formed, with the bath molecules have been accurately calculated. These cross sections are used to calculate the collisional width in three variations of the impact approximation that have been proposed for this problem. In general, the quasistatic approximation is shown to satisfy the usual conditions of muon-catalyzed fusion better than does the impact approximation. A preliminary rough treatment is presented to illustrate the quasistatic approximation.

Covariances for the 56Fe radiation damage cross sections

NASA Astrophysics Data System (ADS)

Simakov, Stanislav P.; Koning, Arjan; Konobeyev, Alexander Yu.

2017-09-01

The energy-energy and reaction-reaction covariance matrices were calculated for the n + 56Fe damage cross-sections by Total Monte Carlo method using the TENDL-2013 random files. They were represented in the ENDF-6 format and added to the unperturbed evaluation file. The uncertainties for the spectrum averaged radiation quantities in the representative fission, fusion and spallation facilities were first time assessed as 5-25%. Additional 5 to 20% have to be added to the atom displacement rate uncertainties to account for accuracy of the primary defects simulation in materials. The reaction-reaction correlation were shown to be 1% or less.

On the connection between the Koppel-Young and the Nelkin Models for thermal neutron scattering in water molecules

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

Markovic, M.I.

1982-10-01

A critical analysis of the Koppel-Young model is presented and compared with Nelkin's model and their equivalence is asserted. It is shown that the only distinction between the two models is in the orientational averaging of the rotational-vibrational intermedial scattering function. Based on total cross sections, the Krieger-Nelkin orientation averaging has been confirmed to give excellent agreement with the Koppel-Young orientation averaging. However, significant quasi-periodical differences are observed when calculating differential cross sections. As a result of these insights, a new unified model is proposed for microdynamics of water molecules.

Cochlear mechanics: Analysis for a pure tone

NASA Astrophysics Data System (ADS)

Holmes, M. H.; Cole, J. D.

1983-11-01

The dynamical response of a three-dimensional hydroelastic model of the cochlea is studied for a pure tone forcing. The basilar membrane is modeled as an inhomogenous, orthotropic elastic plate and the fluid is assumed to be Newtonian. The resulting mathematical problem is reduced using viscous boundary layer theory and slender body approximations. This leads to a nonlinear eigenvalue problem in the transverse cross-section. The solutions for the case of a rectangular and semi-circular cross-section are computed and comparison is made with experiment. The role of the place principle in determining the difference limen is presented and it is shown how the theory agrees with the experimental measurements.

Resonance strength measurement at astrophysical energies: The {sup 17}O(p,α){sup 14}N reaction studied via Trojan Horse Method

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

Sergi, M. L., E-mail: sergi@lns.infn.it; La Cognata, M.; Pizzone, R. G.

2015-10-15

In recent years, the Trojan Horse Method (THM) has been used to investigate the low-energy cross sections of proton-induced reactions on {sup 17}O nuclei, overcoming extrapolation procedures and enhancement effects due to electron screening. We will report on the indirect study of the {sup 17}O(p,α){sup 14}N reaction via the THM by applying the approach developed for extracting the resonance strength of narrow resonance in the ultralow energy region. Two measurements will be described and the experimental THM cross sections will be shown for both experiments.

Solutions of the Helmholtz equation with boundary conditions for force-free magnetic fields

NASA Technical Reports Server (NTRS)

Rasband, S. N.; Turner, L.

1981-01-01

It is shown that the solution, with one ignorable coordinate, for the Taylor minimum energy state (resulting in a force-free magnetic field) in either a straight cylindrical or a toroidal geometry with arbitrary cross section can be reduced to the solution of either an inhomogeneous Helmholtz equation or a Grad-Shafranov equation with simple boundary conditions. Standard Green's function theory is, therefore, applicable. Detailed solutions are presented for the Taylor state in toroidal and cylindrical domains having a rectangular cross section. The focus is on solutions corresponding to the continuous eigenvalue spectra. Singular behavior at 90 deg corners is explored in detail.

Analysis of warping deformation modes using higher order ANCF beam element

NASA Astrophysics Data System (ADS)

Orzechowski, Grzegorz; Shabana, Ahmed A.

2016-02-01

Most classical beam theories assume that the beam cross section remains a rigid surface under an arbitrary loading condition. However, in the absolute nodal coordinate formulation (ANCF) continuum-based beams, this assumption can be relaxed allowing for capturing deformation modes that couple the cross-section deformation and beam bending, torsion, and/or elongation. The deformation modes captured by ANCF finite elements depend on the interpolating polynomials used. The most widely used spatial ANCF beam element employs linear approximation in the transverse direction, thereby restricting the cross section deformation and leading to locking problems. The objective of this investigation is to examine the behavior of a higher order ANCF beam element that includes quadratic interpolation in the transverse directions. This higher order element allows capturing warping and non-uniform stretching distribution. Furthermore, this higher order element allows for increasing the degree of continuity at the element interface. It is shown in this paper that the higher order ANCF beam element can be used effectively to capture warping and eliminate Poisson locking that characterizes lower order ANCF finite elements. It is also shown that increasing the degree of continuity requires a special attention in order to have acceptable results. Because higher order elements can be more computationally expensive than the lower order elements, the use of reduced integration for evaluating the stress forces and the use of explicit and implicit numerical integrations to solve the nonlinear dynamic equations of motion are investigated in this paper. It is shown that the use of some of these integration methods can be very effective in reducing the CPU time without adversely affecting the solution accuracy.

Determination of channel capacity of the Mokelumne River downstream from Camanche Dam, San Joaquin and Sacramento Counties, California

USGS Publications Warehouse

Simpson, R.G.

1972-01-01

This study evaluates the adequacy of a 39-mile reach of the Mokelumne River in San Joaquin and Sacramento Counties, California, to carry planned flood releases between Camanche Reservoir and the Bensons Ferry Bridge near Thornton. The flood releases from Camanche Reservoir are to be restricted, insofar as possible, so that the flows in the Mokelumne River will not exceed 5,000 cfs (cubic feet per second) as measured at the gaging station below Camanche Dam. Areas of inundation and computed floodwater profiles are based on channel conditions in late 1970 and on observed water-surface profiles during flood releases of about 5,000 cfs in January 1969 and January 1970. The inundated area shown on the maps (appendix A) and the water-surface elevations indicated on the cross sections (appendix G) are for the flood releases of those dates. The following conclusions are contingent on there being no levee failures during periods of high flow and no significant channel changes since the flood release of January 1970. 1. High tides in San Francisco Bay and, to a greater degree, flood stages on the Cosumnes River, cause backwater in the study reach. Severe backwater conditions occurring simultaneously with a flow of 5,000 cfs in the Mokelumne River can increase the flood stage 4 to 6 feet at Bensons Ferry Bridge (cross section 1). Backwater effects decrease in an upstream direction and are less than 0.5 foot at cross section 35, a river distance of 8.6 miles upstream from cross section 1, and 1.5 miles downstream from the Peltier Road bridge. 2. In the reach between cross sections 1 and 35, a 5,000 cfs release from Camanche Reservoir with maximum backwater effect (measured at cross section 1 at the mouth of the Cosumnes River) is confined within the natural or leveed banks except on the right bank flood plain between cross sections 12 and 19. 3. Upstream from cross section 35, there is overbank flooding at a flow of 5,000 cfs between cross sections 48 and 51, and 62 and 67.5. An increase in flow from 5,000 to 6,000 cfs will cause flooding between cross sections 43 and 47, 52 and 56, and 73 and 85. 4. A discharge of 5,000 cfs will pass through all bridge openings in the study reach except that of the Western Pacific Railroad Co. bridge at cross section 4. If large amounts of debris lodge on the railroad bridge when backwater from the Cosumnes River occurs, the debris could cause higher stages and flooding along the right bank between cross sections 5 and 12.

FDTD modeling of thin impedance sheets

NASA Technical Reports Server (NTRS)

Luebbers, Raymond J.; Kunz, Karl S.

1991-01-01

Thin sheets of resistive or dielectric material are commonly encountered in radar cross section calculations. Analysis of such sheets is simplified by using sheet impedances. In this paper it is shown that sheet impedances can be modeled easily and accurately using Finite Difference Time Domain (FDTD) methods.

L -subshell ionization of Ce, Nd, and Lu by 4-10-MeV C ions

NASA Astrophysics Data System (ADS)

Lapicki, G.; Mandal, A. C.; Santra, S.; Mitra, D.; Sarkar, M.; Bhattacharya, D.; Sen, P.; Sarkadi, L.; Trautmann, D.

2005-08-01

Ll,Lα,Lβ,Lγ,Lγ1+5,Lγ2+3,Lγ4+4' x-ray production cross sections of Ce58 , Nd60 and Lu71 induced by 4-, 6-, 8-, and 10-MeV carbon ions were measured. For Lu, Lγ2+3 is separated from Lγ2+3+6 after revision of the technique of Datz so that Lγ1+5 was used instead of Lγ1 , the Lγ4+4'/Lγ1+5 ratio was corrected for multiple ionization, and uncertainties in Lγ4+4' were incorporated in the fitting process. L -subshell ionization cross sections were extracted as a weighted average from two combinations of these cross sections, {Lα,Lγ1+5,Lγ2+3} and {Lα,Lγ1+5,Lγ} . It is shown that, to within a few percent, the first of these two combinations results in the identical cross sections as this weighted average. Within 10%, permutations of different sets of single-hole atomic parameters yielded the same ionization cross sections. These cross sections are typically within 15% and at most 35% of the cross sections obtained with atomic parameters that were altered in two different ways for multiple ionization. Extracted subshell and total L -shell ionization cross sections as well as Ce and Nd data of Braziewicz are compared with the ECPSSR theory of Brandt and Lapicki that accounts for the energy-loss (E), Coulomb-deflection (C), perturbed-stationary-state (PSS) and relativistic (R) effects. These measurements are also compared with the ECPSSR theory after its corrections—in a separated and united atom (USA) treatment, and for the intrashell (IS) transitions with the factors of Sarkadi and Mukoyama normalized to match L -shell cross section with the sum of L -subshell cross sections—as well as with the similarly improved semiclassical approximation of Trautmann. For Ce and Nd, the agreement of the extracted ionization cross sections with these theories is poor for L1 and good for L2 , L3 , and total L shell ionization. For the L2 subshell, this agreement is better for Ce and Nd than for Lu. The ECPSSR theory corrected for the USA and IS effects is surprisingly good for the L1 -subshell ionization of Lu, while at 4MeV a similarly corrected semiclassical approximation is in excellent agreement with L2 and L3 data but overestimates the L1 measurement by almost a factor of 2.

High-Energy Electron-Induced SEUs and Jovian Environment Impact

NASA Astrophysics Data System (ADS)

Tali, Maris; Alía, Rubén García; Brugger, Markus; Ferlet-Cavrois, Veronique; Corsini, Roberto; Farabolini, Wilfrid; Mohammadzadeh, Ali; Santin, Giovanni; Virtanen, Ari

2017-08-01

We present experimental evidence of electron-induced upsets in a reference European Space Agency (ESA) single event upset (SEU) monitor, induced by a 200-MeV electron beam at the Very energetic Electronic facility for Space Planetary Exploration in harsh Radiation environments facility at CERN. Comparison of experimental cross sections and simulated cross sections is shown and the differences are analyzed. Possible secondary contributions to the upset rate by neutrons, flash effects, and cumulative dose effects are discussed, showing that electronuclear reactions are the expected SEU mechanism. The ESA Jupiter Icy Moons Explorer mission, to be launched in 2022, presents a challenging radiation environment due to the intense high-energy electron flux in the trapped radiation belts. Insight is given to the possible contribution of electrons to the overall upset rates in the Jovian radiation environment. Relative contributions of both typical electron and proton spectra created when the environmental spectra are transported through a typical spacecraft shielding are shown and the different mission phases are discussed.

Optical potential approach to the electron-atom impact ionization threshold problem

NASA Technical Reports Server (NTRS)

Temkin, A.; Hahn, Y.

1973-01-01

The problem of the threshold law for electron-atom impact ionization is reconsidered as an extrapolation of inelastic cross sections through the ionization threshold. The cross sections are evaluated from a distorted wave matrix element, the final state of which describes the scattering from the Nth excited state of the target atom. The actual calculation is carried for the e-H system, and a model is introduced which is shown to preserve the essential properties of the problem while at the same time reducing the dimensionability of the Schrodinger equation. Nevertheless, the scattering equation is still very complex. It is dominated by the optical potential which is expanded in terms of eigen-spectrum of QHQ. It is shown by actual calculation that the lower eigenvalues of this spectrum descend below the relevant inelastic thresholds; it follows rigorously that the optical potential contains repulsive terms. Analytical solutions of the final state wave function are obtained with several approximations of the optical potential.

Numerical analysis of flows of rarefied gases in long channels with octagonal cross section shapes

NASA Astrophysics Data System (ADS)

Szalmas, L.

2014-12-01

Isothermal, pressure driven rarefied gas flows through long channels with octagonal cross section shapes are analyzed computationally. The capillary is between inlet and outlet reservoirs. The cross section is constant along the axial direction. The boundary condition at the solid-gas interface is assumed to be diffuse reflection. Since the channel is long, the gaseous velocity is small compared to the average molecular speed. Consequently, a linearized description can be used. The flow is described by the linearized Bhatnagar-Gross-Krook kinetic model. The solution of the problem is divided into two stages. First, the local flow field is determined by assuming the local pressure gradient. Secondly, the global flow behavior is deduced by the consideration of the conservation of the mass along the axis of the capillary. The kinetic equation is solved by the discrete velocity method on the cross section. Both spatial and velocity spaces are discretized. A body fitted rectangular grid is used for the spatial space. Near the boundary, first-order, while in the interior part of the flow domain, second-order finite-differences are applied to approximate the spatial derivatives. This combination results into an efficient and straightforward numerical treatment. The velocity space is represented by a Gauss-Legendre quadrature. The kinetic equation is solved in an iterative manner. The local dimensionless flow rate is calculated and tabulated for a wide range of the gaseous rarefaction for octagonal cross sections with various geometrical parameters. It exhibits the Knudsen minimum phenomenon. The flow rates in the octagonal channel are compared to those through capillaries with circular and square cross sections. Typical velocity profiles are also shown. The mass flow rate and the distribution of the pressure are determined and presented for global pressure driven flows.

Measurements of cross-section of charge current inclusive of antineutrino scattering off nucleons using carbon, iron, lead and scintillator at MINER$$\

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

Rakotondravohitra, Laza

2015-08-18

Neutrino physics is one of the most active fields in the domaine of high energy physics during the last century. The need of precise measurement of neutrino-nucleus interactions required by the neutrino oscillation experiments is a an exiting step. These measurements of cross-section are more than essential for neutrino oscillation experiment. Over the year, many measurements from varieties of experiments have been presented. MINERνA is one of the world leaders in measuring cross-section of neutrino and antineutrino -nucleus interactions. MINERνA is a neutrino-nucleus scattering experiment installed in the few-GeV NuMI beam line at Fermilab. In order to study nuclear dependence,more » MINERνA is endowed with different types of solid nuclear targets as well are liquid targets such as helium and water. This thesis presents measurements of cross-section of antineutrino scattering off nucleons using a variety of solid nuclear targets, carbon, iron, lead and also polystyrene scintillator (CH). The data set of antineutrino used for this analysis was taken between March and July 2010 with a total of 1.60X10 20 protons on target. Charged current inclusive interactions were selected by requiring a positive muon and kinematics limitation of acceptance of the muon spectrometer are applied. The analysis requires neutrino energy between 2GeV et 20GeV and the angle of muon θ mu < 17degree . The absolute cross-section # as function of neutrino energy and the differential cross-section dσ/ dx bj measured and shown the corresponding systematics for each nuclear targets. Data results are compared with prediction of the models implemented in the neutrino events generators GENIE 2.6.2 used by the experiment.« less

New method for evaluation of bendability based on three-point-bending and the evolution of the cross-section moment

NASA Astrophysics Data System (ADS)

Troive, L.

2017-09-01

Friction-free 3-point bending has become a common test-method since the VDA 238-100 plate-bending test [1] was introduced. According to this test the criterion for failure is when the force suddenly drops. It was found by the author that the evolution of the cross-section moment is a more preferable measure regarding the real material response instead of the force. Beneficially, the cross-section moment gets more or less a constant maximum steady-state level when the cross-section becomes fully plastified. An expression for the moment M is presented that fulfils the criteria for energy of conservation at bending. Also an expression calculating the unit-free moment, M/Me, i.e. current moment to elastic-moment ratio, is demonstrated specifically proposed for detection of failures. The mathematical expressions are simple making it easy to transpose measured force F and stroke position S to the corresponding cross-section moment M. From that point of view it’s even possible to implement, e.g. into a conventional measurement system software, studying the cross-section moment in real-time during a test. It’s even possible to calculate other parameters such as flow-stress and shape of curvature at every stage. It has been tested on different thicknesses and grades within the range from 1.0 to 10 mm with very good results. In this paper the present model is applied on a 6.1 mm hot-rolled high strength steel from the same batch at three different conditions, i.e. directly quenched, quenched and tempered, and a third variant quench and tempered with levelling. It will be shown that very small differences in material-response can be predicted by this method.

Use of corrected centrifugal sudden approximations for the calculation of effective cross sections. II. The N sub 2 --He system

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

Thachuk, M.; McCourt, F.R.W.

1991-09-15

A series of centrifugal sudden (CS) and infinite-order sudden (IOS) approximations together with their corrected versions, respectively, the corrected centrifugal sudden (CCS) and corrected infinite-order sudden (CIOS) approximations, originally introduced by McLenithan and Secrest (J. Chem. Phys. {bold 80}, 2480 (1987)), have been compared with the close-coupled (CC) method for the N{sub 2}--He interaction. This extends previous work using the H{sub 2}--He system (J. Chem. Phys. {bold 93}, 3931 (1990)) to an interaction which is more anisotropic and more classical in nature. A set of eleven energy dependent cross sections, including both relaxation and production types, has been calculated usingmore » the {ital LF}- and {ital LA}-labeling schemes for the CS approximation, as well as the {ital KI}-, {ital KF}-, {ital KA}-, and {ital KM}-labeling schemes for the IOS approximation. The latter scheme is defined as {ital KM}={ital K}=max({ital k}{sub {ital j}},{ital k}{sub {ital j}{sub {ital I}}}). Further, a number of temperature dependent cross sections formed from thermal averages of the above set have also been compared at 100 and 200 K. These comparisons have shown that the CS approximation produced accurate results for relaxation type cross sections regardless of the {ital L}-labeling scheme chosen, but inaccurate results for production type cross sections. Further, except for one particular cross section, the CCS approximation did not generally improve the accuracy of the CS results using either the {ital LF}- or {ital LA}-labeling schemes. The accuracy of the IOS results vary greatly between the cross sections with the most accurate values given by the {ital KM}-labeling scheme. The CIOS approximation generally increases the accuracy of the corresponding IOS results but does not completely eliminate the errors associated with them.« less

Making baryons dark: the quantum prediction of the variation of photon-particle scattering cross section with the approach to equilibrium in deep gravity wells

NASA Astrophysics Data System (ADS)

Ernest, Alllan David; Collins, Matthew P.

2015-08-01

Analysis of astrophysical phenomena relies on knowledge of cross sections. These cross sections are measured in scattering experiments, or calculated using theoretical techniques such as partial wave analysis. It has been recently shown [1,2,3] however that photon scattering cross sections depend also on the degree of localization of the target particle, and that particles in large-scale, deep-gravity wells can exhibit lower cross sections than those measured in lab-based experiments where particles are implicitly localized. This purely quantum effect arises as a consequence of differences in the gravitational eigenspectral distribution of a particle’s wavefunction in different situations, and is in addition to the obvious notion that delocalized particle scattering is less likely simply because the target particles are ‘in a bigger box’.In this presentation we consider the quantum equilibrium statistics of particles in gravitational potentials corresponding to dark matter density profiles. We show that as galactic halos approach equilibrium, the dark eigenstates of the eigenspectral ensemble are favoured and baryons exhibit lower photon scattering cross sections, rendering halos less visible than expected from currently accepted cross sections. Traditional quantum theory thus predicts that baryons that have not coalesced into self-bound macroscopic structures such as stars, can essentially behave as dark matter simply by equilibrating within a deep gravity well. We will discuss this effect and the consequences for microwave anisotropy analysis and primordial nucleosynthesis.[1] Ernest, A. D., and Collins, M. P., 2014, Australian Institute of Physics, AIP Congress, Canberra, December, 2014.[2] Ernest, A. D., 2009, J. Phys. A: Math. Theor., 42, 115207, 115208.[3] Ernest, A. D., 2012, In Prof. Ion Cotaescu (Ed) Advances in Quantum Theory (pp 221-248). Rijeka: InTech. ISBN 978-953-51-0087-4

Modern status of photonuclear data

NASA Astrophysics Data System (ADS)

Varlamov, V. V.; Ishkhanov, B. S.

2017-09-01

The reliability of experimental cross sections obtained for (γ, 1 n), (γ, 2 n), and (γ, 3 n) partial photoneutron reactions using beams of quasimonoenergetic annihilation photons and bremsstrahlung is analyzed by employing data for a large number of medium-heavy and heavy nuclei, including those of 63,65Cu, 80Se, 90,91,94Zr, 115In, 112-124Sn, 133Cs, 138Ba, 159Tb, 181Ta, 186-192Os, 197Au, 208Pb, and 209Bi. The ratios of the cross sections of definite partial reactions to the cross section of the neutron-yield reaction, F i = σ(γ, in)/ σ(γ, xn), are used as criteria of experimental-data reliability. By definition, positive values of these ratios should not exceed the upper limits of 1.00, 0.50, 0.33,... for i = 1, 2, 3,..., respectively. For many nuclei, unreliable values of the above ratios were found to correlate clearly in various photon-energy regions F i with physically forbidden negative values of cross sections of partial reactions. On this basis, one can conclude that correspondent experimental data are unreliable. Significant systematic uncertainties of the methods used to determine photoneutron multiplicity are shown to be the main reason for this. New partial-reaction cross sections that satisfy the above data-reliability criteria were evaluated within an experimental-theoretical method [ σ eval(γ, in) = F i theor (γ, in) × σ expt(γ, xn)] by employing the ratios F i theor (γ, in) calculated on the basis of a combined photonuclear-reaction model. It was obtained that cross sections evaluated in this way deviate substantially from the results of many experiments performed via neutron-multiplicity sorting, but, at the same time, agree with the results of alternative activation experiments. Prospects of employing methods that would provide, without recourse to photoneutron-multiplicity sorting, reliable data on cross sections of partial photoneutron reactions are discussed.

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

Younes, W; Britt, H C; Wilhelmy, J B

The purpose of this note is to combine existing information on the {sup 237}U(n,f) cross section to determine if some consistency can be obtained for the neutron induced fission excitation of {sup 237}U. The neutron induced fission cross section of the 6.8 day {sup 237}U was measured directly by McNally et al. in 1968 using the Pommard nuclear device test. At the same time critical assembly measurements were done at Los Alamos using the Flattop assembly. A previous measurement was also made at LASL in 1954 with two different neutron sources, each peaked near 200 keV. The results were 0.66more » {+-} 0.10 b and 0.70 {+-} 0.07 b for the (n,f) cross section. More recently Younes and Britt have reanalyzed direct reaction charged particle data of Cramer and Britt that had determined the fission probability of the {sup 238}U compound nucleus as a function of nuclear excitation energy. They have combined fission probabilities with calculated neutron absorption cross sections, including corrections for the differences in angular momentum between the direct and neutron induced reactions. From this analysis they have extracted equivalent {sup 237}U(n,f) cross sections. The technique for extracting surrogate (n,f) cross sections from (t,pf) data has been demonstrated in a recent publication for the test case {sup 235}U(n,f). In addition to this experimental information, Lynn and Hayes have recently done a new theoretical study of the fission cross sections for a series of isotopes in this region. A summary plot of the data is shown in Fig. 1. Below 0.5 MeV the McNally, Cowan, and Younes-Britt results are in reasonable agreement. The average cross section in the Younes-Britt results, for En = 0.1 to 0.4 MeV, is 0.80 times the McNally values which is well within the errors of the McNally experiment. Above 0.5 MeV the McNally results diverge toward higher values. It should be noted that this divergence begins approximately at the {sup 237}Np threshold and that {sup 237}Np is the daughter of the 6.8 day {sup 237}U decay.« less

Development of ORIGEN Libraries for Mixed Oxide (MOX) Fuel Assembly Designs

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

Mertyurek, Ugur; Gauld, Ian C.

In this research, ORIGEN cross section libraries for reactor-grade mixed oxide (MOX) fuel assembly designs have been developed to provide fast and accurate depletion calculations to predict nuclide inventories, radiation sources and thermal decay heat information needed in safety evaluations and safeguards verification measurements of spent nuclear fuel. These ORIGEN libraries are generated using two-dimensional lattice physics assembly models that include enrichment zoning and cross section data based on ENDF/B-VII.0 evaluations. Using the SCALE depletion sequence, burnup-dependent cross sections are created for selected commercial reactor assembly designs and a representative range of reactor operating conditions, fuel enrichments, and fuel burnup.more » The burnup dependent cross sections are then interpolated to provide problem-dependent cross sections for ORIGEN, avoiding the need for time-consuming lattice physics calculations. The ORIGEN libraries for MOX assembly designs are validated against destructive radiochemical assay measurements of MOX fuel from the MALIBU international experimental program. This program included measurements of MOX fuel from a 15 × 15 pressurized water reactor assembly and a 9 × 9 boiling water reactor assembly. The ORIGEN MOX libraries are also compared against detailed assembly calculations from the Phase IV-B numerical MOX fuel burnup credit benchmark coordinated by the Nuclear Energy Agency within the Organization for Economic Cooperation and Development. Finally, the nuclide compositions calculated by ORIGEN using the MOX libraries are shown to be in good agreement with other physics codes and with experimental data.« less

Measurement of Muon Neutrino Charged Current Single $$\\pi^0$$ Production on Hydrocarbon using MINERvA

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

Altinok, Ozgur

A sample of charged-current single pion production events for the semi- exclusive channel ν µ + CH → µ -π 0 + nucleon(s) has been obtained using neutrino exposures of the MINERvA detector. Differential cross sections for muon momentum, muon production angle, pion momentum, pion production angle, and four-momentum transfer square Q 2 are reported and are compared to a GENIE-based simulation. The cross section versus neutrino energy is also re- ported. The effects of pion final-state interactions on these cross sections are investigated. The effect of baryon resonance suppression at low Q 2 is examined and an event re-weight used by two previous experiments is shown to improve the data versus simulation agreement. The differential cross sections for Q 2 for Eν < 4.0 GeV and E ν ≥ 4.0 GeV are examined and the shapes of these distributions are compared to those from the experiment’smore » $$\\bar{v}$$ µ-CC (π 0) measurement. The polarization of the pπ 0 system is measured and compared to the simulation predictions. The hadronic invariant mass W distribution is examined for evidence of resonance content, and a search is reported for evidence of a two-particle two-hole (2p2h) contribution. All of the differential cross-section measurements of this Thesis are compared with published MINERvA measurements for ν µ-CC (π +) and \\bar{v}$ µ-CC (π 0) processes.« less

Extended optical model for fission

DOE PAGES

Sin, M.; Capote, R.; Herman, M. W.; ...

2016-03-07

A comprehensive formalism to calculate fission cross sections based on the extension of the optical model for fission is presented. It can be used for description of nuclear reactions on actinides featuring multi-humped fission barriers with partial absorption in the wells and direct transmission through discrete and continuum fission channels. The formalism describes the gross fluctuations observed in the fission probability due to vibrational resonances, and can be easily implemented in existing statistical reaction model codes. The extended optical model for fission is applied for neutron induced fission cross-section calculations on 234,235,238U and 239Pu targets. A triple-humped fission barrier ismore » used for 234,235U(n,f), while a double-humped fission barrier is used for 238U(n,f) and 239Pu(n,f) reactions as predicted by theoretical barrier calculations. The impact of partial damping of class-II/III states, and of direct transmission through discrete and continuum fission channels, is shown to be critical for a proper description of the measured fission cross sections for 234,235,238U(n,f) reactions. The 239Pu(n,f) reaction can be calculated in the complete damping approximation. Calculated cross sections for 235,238U(n,f) and 239Pu(n,f) reactions agree within 3% with the corresponding cross sections derived within the Neutron Standards least-squares fit of available experimental data. Lastly, the extended optical model for fission can be used for both theoretical fission studies and nuclear data evaluation.« less

Resonant parametric interference effect in spontaneous bremsstrahlung of an electron in the field of a nucleus and two pulsed laser waves

NASA Astrophysics Data System (ADS)

Lebed', A. A.; Padusenko, E. A.; Roshchupkin, S. P.; Dubov, V. V.

2018-04-01

Electron-nucleus bremsstrahlung in the field of two moderately strong pulsed laser waves in the case of incommensurate frequencies is theoretically studied under resonant conditions. The process is studied in detail in a special kinematic region, where stimulated processes with correlated emission and absorption of photons of the first and second waves become predominant (parametric interference effect). The availability of this region is caused by interference of the first and second laser waves. The correspondence between the emission angle and the final-electron energy is established in this interference kinematic. In this case, the cross-sectional properties are determined by the multiphoton quantum interference parameter, which is proportional to the product of intensities of the first and second waves. The resonant differential cross section of electron-nucleus spontaneous bremsstrahlung with simultaneous registration of both emission angles of the spontaneous photon and the scattered electron can exceed by four or five orders of magnitude the corresponding cross section in the absence of an external field. It was shown for nonrelativistic electrons that the resonant cross section of the studied process in the field of two pulsed laser waves within the interference region in two order of magnitude may exceed corresponding cross sections at other scattering kinematics. The obtained results may be experimentally verified, for example, by scientific facilities at sources of pulsed laser radiation (such as SLAC, FAIR, XFEL, ELI).

Development of ORIGEN Libraries for Mixed Oxide (MOX) Fuel Assembly Designs

DOE PAGES

Mertyurek, Ugur; Gauld, Ian C.

2015-12-24

In this research, ORIGEN cross section libraries for reactor-grade mixed oxide (MOX) fuel assembly designs have been developed to provide fast and accurate depletion calculations to predict nuclide inventories, radiation sources and thermal decay heat information needed in safety evaluations and safeguards verification measurements of spent nuclear fuel. These ORIGEN libraries are generated using two-dimensional lattice physics assembly models that include enrichment zoning and cross section data based on ENDF/B-VII.0 evaluations. Using the SCALE depletion sequence, burnup-dependent cross sections are created for selected commercial reactor assembly designs and a representative range of reactor operating conditions, fuel enrichments, and fuel burnup.more » The burnup dependent cross sections are then interpolated to provide problem-dependent cross sections for ORIGEN, avoiding the need for time-consuming lattice physics calculations. The ORIGEN libraries for MOX assembly designs are validated against destructive radiochemical assay measurements of MOX fuel from the MALIBU international experimental program. This program included measurements of MOX fuel from a 15 × 15 pressurized water reactor assembly and a 9 × 9 boiling water reactor assembly. The ORIGEN MOX libraries are also compared against detailed assembly calculations from the Phase IV-B numerical MOX fuel burnup credit benchmark coordinated by the Nuclear Energy Agency within the Organization for Economic Cooperation and Development. Finally, the nuclide compositions calculated by ORIGEN using the MOX libraries are shown to be in good agreement with other physics codes and with experimental data.« less

Developmental changes in coping: situational and methodological influences.

PubMed

Vierhaus, Marc; Lohaus, Arnold; Ball, Juliane

2007-09-01

Previous studies on the development of coping have shown rather inconsistent findings regarding the developmental trajectories for different coping dimensions. The aim of this study is to search for possible influences that might explain these inconsistencies. The analysis focuses on methodological influences (longitudinal vs. cross-sectional assessments) and situational influences. Two samples of children were traced longitudinally with yearly assessments from grade 2 to 5 (sample 1, N =432) and from grade 4 to 7 (sample 2, N =366). A third sample (N =849) was added with cross-sectional assessments from grade 2 to 7. The assessed coping dimensions were related to (a) problem solving, (b) seeking social support, (c) palliative coping, (d) externalizing emotional coping, and (e) avoidant coping. The use of the coping strategies had to be assessed for six stress-evoking situations. The results show only small differences between the longitudinal and the cross-sectional coping assessments. There are, however, clear situational influences on the choice of the coping strategies and also on the resulting developmental trajectories.

Microwave signatures of snow, ice and soil at several wavelengths

NASA Technical Reports Server (NTRS)

Gloersen, P.; Schmugge, T. J.; Chang, T. C.

1974-01-01

Analyses of data obtained from aircraft-borne radiometers have shown that the microwave signatures of various parts of the terrain depend on both the volume scattering cross-section and the dielectric loss in the medium. In soil, it has been found that experimental data fit a model in which the scattering cross section is negligible compared to the dielectric loss. On the other hand, the volume scattering cross-section in snow and continental ice was found, from analyzing data obtained with aircraft- and spacecraft-borne radiometers, to be more important than the dielectric loss or surface reflectivity in determining the observed microwave emissivity. A model which assumes Mie scattering of ice particles of various sizes was found to be the dominant volume scattering mechanism in these media. Both spectral variation in the microwave signatures of snow and ice fields, as well as the variation in the emissivity of continental ice sheets such as those covering Greenland and Antarctica appear to be consistent with this model.

Pseudostate methods and differential cross sections for antiproton ionization of atomic hydrogen and helium

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

McGovern, M.; Walters, H. R. J.; Assafrao, D.

2010-03-15

A relaxed form of a recent impact parameter coupled pseudostate approximation of McGovern et al. [Phys. Rev. A 79, 042707 (2009)] for calculating differential ionization cross sections is proposed. This greatly eases the computational burden in cases where a range of ejected electron energies has to be considered. The relaxed approximation is tested against exact first Born calculations for antiproton impact on H and nonperturbatively for the highly nonperturbative system of Au{sup 53+} incident upon He. The approximation performs well in these tests. It is shown how, with a little further approximation, the relaxed theory leads to a widely usedmore » prescription for the total ionization cross section. Results for differential ionization of H and He by antiprotons are presented. These reveal the growing dominance of the interaction between the antiproton and the target nucleus at low impact energies and show the changing importance of the role of the postcollisional interaction between the antiproton and the ejected electron.« less

Quantum-mechanical predictions of electron-induced ionization cross sections of DNA components

NASA Astrophysics Data System (ADS)

Champion, Christophe

2013-05-01

Ionization of biomolecules remains still today rarely investigated on both the experimental and the theoretical sides. In this context, the present work appears as one of the first quantum mechanical approaches providing a multi-differential description of the electron-induced ionization process of the main DNA components for impact energies ranging from the target ionization threshold up to about 10 keV. The cross section calculations are here performed within the 1st Born approximation framework in which the ejected electron is described by a Coulomb wave whereas the incident and the scattered electrons are both described by a plane wave. The biological targets of interest, namely, the DNA nucleobases and the sugar-phosphate backbone, are here described by means of the GAUSSIAN 09 system using the restricted Hartree-Fock method with geometry optimization. The theoretical predictions also obtained have shown a reasonable agreement with the experimental total ionization cross sections while huge discrepancies have been pointed out with existing theoretical models, mainly developed within a semi-classical framework.

Time-resolved flowmetering of gas-liquid two-phase pipe flow by ultrasound pulse Doppler method

NASA Astrophysics Data System (ADS)

Murai, Yuichi; Tasaka, Yuji; Takeda, Yasushi

2012-03-01

Ultrasound pulse Doppler method is applied for componential volumetric flow rate measurement in multiphase pipe flow consisted of gas and liquid phases. The flowmetering is realized with integration of measured velocity profile over the cross section of the pipe within liquid phase. Spatio-temporal position of interface is detected also with the same ultrasound pulse, which further gives cross sectional void fraction. A series of experimental demonstration was shown by applying this principle of measurement to air-water two-phase flow in a horizontal tube of 40 mm in diameter, of which void fraction ranges from 0 to 90% at superficial velocity from 0 to 15 m/s. The measurement accuracy is verified with a volumetric type flowmeter. We also analyze the accuracy of area integration of liquid velocity distribution for many different patterns of ultrasound measurement lines assigned on the cross section of the tube. The present method is also identified to be pulsation sensor of flow rate that fluctuates with complex gas-liquid interface behavior.

Theory of scattering of electromagnetic waves of the microwave range in a turbid medium

NASA Astrophysics Data System (ADS)

Konstantinov, O. V.; Matveentsev, A. V.

2013-02-01

The coefficient of extinction of electromagnetic waves of the microwave range due to their scattering from clusters suspended in an amorphous medium and responsible for turbidity is calculated. Turbidity resembles the case when butter clusters transform water into milk. In the case under investigation, the clusters are conductors (metallic or semiconducting). The extinction coefficient is connected in a familiar way with the cross section of light scattering from an individual cluster. A new formula is derived for the light scattering cross section in the case when damping of oscillations of an electron is due only to spontaneous emission of light quanta. In this case, the resonant scattering cross section for light can be very large. It is shown that this can be observed only in a whisker nanocluster. In addition, the phonon energy on a whisker segment must be higher than the photon energy, which is close to the spacing between the electron energy levels in the cluster.

Measuring and modeling the backscattering cross section of a leaf

NASA Technical Reports Server (NTRS)

Senior, T. B. A.; Sarabandi, K.; Ulaby, F. T.

1987-01-01

Leaves are a significant feature of any vegetation canopy, and for remote sensing purposes it is important to develop an effective model for predicting the scattering from a leaf. From measurements of the X band backscattering cross section of a coleus leaf in varying stages of dryness, it is shown that a uniform resistive sheet constitutes such a model for a planar leaf. The scattering is determined by the (complex) resistivity which is, in turn, entirely specified by the gravimetric moisture content of the leaf. Using an available asymptotic expression for the scattering from a rectangular resistive plate which includes, as a special case, a metallic plate whose resistivity is zero, the computed backscattering cross sections for both principal polarizations are found to be in excellent agreement with data measured for rectangular sections of leaves with different moisture contents. If the resistivity is sufficiently large, the asymptotic expressions do not differ significantly from the physical optics ones, and for naturally shaped leaves as well as rectangular sections, the physical optics approximation in conjunction with the resistive sheet model faithfully reproduces the dominant feataures of the scattering patterns under all moisture conditions.

Density measurement in air with saturable absorbing seed gas

NASA Technical Reports Server (NTRS)

Baganoff, D.

1982-01-01

Approaches which have the potential to make density measurements in a compressible flow, where one or more laser beams are used as probes, were investigated. Saturation in sulfur hexafluoride iodine and a crossed beam technique where one beam acts as a saturating beam and the other is at low intensity and acts as a probe beam are considered. It is shown that a balance between an increase in fluorescence intensity with increasing pressure from line broadening and the normal decrease in intensity with increasing pressure from quenching can be used to develop a linear relation between fluorescence intensity and number density and lead to a new density measurement scheme. The method is used to obtain a density image of the cross section of an iodine seeded underexpanded supersonic jet of nitrogen, by illuminating the cross section by a sheet of laser light.

Backwater at bridges and densely wooded flood plains, west fork Amite River near Liberty, Mississippi

USGS Publications Warehouse

Colson, B.E.; Ming, C.O.; Arcement, George J.

1979-01-01

Floodflow data that will provide a base for evaluating digital models relating to open-channel flow were obtained at 22 sites on streams in Alabama, Louisiana, and Mississippi. Thirty-five floods were measured. Analysis of the data indicated methods currently in use would be inaccurate where densely vegetated flood plains are crossed by highway embankments and single-opening bridges. This atlas presents flood information at the site on West Fork Amite River near Liberty, MS. Water depths , velocities, and discharges through bridge openings on West Fork Amite River near Liberty, MS for floods of December 6, 1971 , and March 25, 1973, are shown, together with peak water-surface elevations along embankments and along cross sections. Manning 's roughness coefficient values in different parts of the flood plain are shown on maps, and flood-frequency relations are shown on a graph. (USGS).

Parent-child interactions and objectively measured child physical activity: a cross-sectional study

USDA-ARS?s Scientific Manuscript database

Parents influence their children's behaviors directly through specific parenting practices and indirectly through their parenting style. Some practices such as logistical and emotional support have been shown to be positively associated with child physical activity (PA) levels, while for others (e.g...

Community Exposure to Air Manganese and Motor and Cognitive Outcomes

EPA Science Inventory

Although manganese (Mn) is an essential nutrient, occupational studies have shown inhaling high levels of Mn can lead to adverse nervous system health effects. Few studies have examined the health effects of air-Mn exposure on adults in a community. We conducted a cross-sectional...

Sleep duration of underserved minority children in a cross-sectional study

USDA-ARS?s Scientific Manuscript database

Short sleep duration has been shown to associate with increased risk of obesity. Childhood obesity is more prevalent among underserved minority children. The study measured the sleep duration of underserved minority children living in a large US urban environment using accelerometry and its relation...

Shear viscosity of an ultrarelativistic Boltzmann gas with isotropic inelastic scattering processes

NASA Astrophysics Data System (ADS)

El, A.; Lauciello, F.; Wesp, C.; Bouras, I.; Xu, Z.; Greiner, C.

2014-05-01

We derive an analytic expression for the shear viscosity of an ultra-relativistic gas in presence of both elastic 2→2 and inelastic 2↔3 processes with isotropic differential cross sections. The derivation is based on the entropy principle and Grad's approximation for the off-equilibrium distribution function. The obtained formula relates the shear viscosity coefficient η to the total cross sections σ22 and σ23 of the elastic resp. inelastic processes. The values of shear viscosity extracted using the Green-Kubo formula from kinetic transport calculations are shown to be in excellent agreement with the analytic results which demonstrates the validity of the derived formula.

On turbulent friction in straight ducts with complex cross-section: the wall law and the hydraulic diameter

NASA Astrophysics Data System (ADS)

Pirozzoli, Sergio

2018-07-01

We develop predictive formulas for friction resistance in ducts with complex cross-sectional shape based on the use of the log law and neglect of wall shear stress nonuniformities. The traditional hydraulic diameter naturally emerges from the analysis as the controlling length scale for common duct shapes as triangles and regular polygons. The analysis also suggests that a new effective diameter should be used in more general cases, yielding corrections of a few percent to friction estimates based on the traditional hydraulic diameter. Fair but consistent predictive improvement is shown for duct geometries of practical relevance, including rectangular and annular ducts, and circular rod bundles.

Out-of-plane dynamic stability analysis of curved beams subjected to uniformly distributed radial loading

NASA Astrophysics Data System (ADS)

Sabuncu, M.; Ozturk, H.; Cimen; S.

2011-04-01

In this study, out-of-plane stability analysis of tapered cross-sectioned thin curved beams under uniformly distributed radial loading is performed by using the finite-element method. Solutions referred to as Bolotin's approach are analysed for dynamic stability, and the first unstable regions are examined. Out-of-plane vibration and out-of-plane buckling analyses are also studied. In addition, the results obtained in this study are compared with the published results of other researchers for the fundamental frequency and critical lateral buckling load. The effects of subtended angle, variations of cross-section, and dynamic load parameter on the stability regions are shown in graphics

Some aspects of the stability of the plane deformation mode of filaments of finite stiffness beyond the elasticity limits

NASA Astrophysics Data System (ADS)

Shimanovskii, A. V.

A method for calculating the plane bending of elastic-plastic filaments of finite stiffness is proposed on the basis of plastic flow theory. The problem considered is shown to reduce to relations similar to Kirchhoff equations for elastic work. Expressions are obtained for determining the normalized stiffness characteristics for the cross section of a filament with plastic regions containing beam theory equations as a particular case. A study is made of the effect of the plastic region size on the position of the elastic deformation-unloading interface and on the normalized stiffness of the filament cross section. Calculation results are presented in graphic form.

Best estimate of luminal cross-sectional area of coronary arteries from angiograms

NASA Technical Reports Server (NTRS)

Lee, P. L.; Selzer, R. H.

1988-01-01

We have reexamined the problem of estimating the luminal area of an elliptically-shaped coronary artery cross section from two or more radiographic diameter measurements. The expected error is found to be much smaller than the maximum potential error. In the cae of two orthogonal views, closed form expressions have been derived for calculating the area and the uncertainty. Assuming that the underlying ellipse has limited ellipticity (major/minor axis ratio less than five), it is shown that the average uncertainty in the area is less than 14 percent. When more than two views are available, we suggest using a least-squares fit method to extract all available information from the data.

Structure of 8Li from a reaction cross-section measurement

NASA Astrophysics Data System (ADS)

Fan, G. W.; Fukuda, M.; Nishimura, D.; Cai, X. L.; Fukuda, S.; Hachiuma, I.; Ichikawa, C.; Izumikawa, T.; Kanazawa, M.; Kitagawa, A.; Kuboki, T.; Lantz, M.; Mihara, M.; Nagashima, M.; Namihira, K.; Ohkuma, Y.; Ohtsubo, T.; Ren, Zhongzhou; Sato, S.; Shen, Z. Q.; Sugiyama, M.; Suzuki, S.; Suzuki, T.; Takechi, M.; Yamaguchi, T.; Xu, B. J.; Xu, W.

2014-10-01

We have precisely measured reaction cross sections (σR) for 8Li using 9Be, 12C , 27Al, and proton targets at intermediate energies by the transmission method. From the energy dependence of the σR including the high energy data, the density distribution of 8Li was deduced through a modified Glauber model. It is shown that 8Li has a shorter tail structure in the density as compared with that of 8B and the matter radius of 8Li is similar to those of the other nonhalo Li isotopes. The result is consistent with the previous experiments that there is a tendency for 8Li to be a skin nucleus.

Shear-horizontal vibration modes of an oblate elliptical cylinder and energy trapping in contoured acoustic wave resonators.

PubMed

He, Huijing; Yang, Jiashi; Kosinski, John A

2012-08-01

We study shear-horizontal free vibrations of an elastic cylinder with an oblate elliptical cross section and a traction-free surface. Exact vibration modes and frequencies are obtained. The results show the existence of thickness-shear and thickness-twist modes. The energy-trapping behavior of these modes is examined. Trapped modes are found wherein the vibration energy is largely confined to the central portion of the cross section and little vibration energy is found at the edges. It is also shown that face-shear modes are not allowed in such a cylinder. The results are useful for the understanding of the energy trapping phenomenon in contoured acoustic wave resonators.

Measurement of double-differential cross sections for top quark pair production in pp collisions at $$\\sqrt{s} = 8$$ TeV and impact on parton distribution functions

DOE PAGES

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; ...

2017-07-11

Normalized double-differential cross sections for top quark pair (more » $$\\mathrm{t}\\overline{\\mathrm{t}}$$ ) production are measured in pp collisions at a centre-of-mass energy of 8 $$\\,\\text {TeV}$$ with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7 $$\\,\\text {fb}^{-1}$$ . The measurement is performed in the dilepton $$\\mathrm {e}^{\\pm }\\mu ^{\\mp }$$ final state. The $$\\mathrm{t}\\overline{\\mathrm{t}}$$ cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and $$\\mathrm{t}\\overline{\\mathrm{t}}$$ system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. Lastly, the inclusion of the measured $$\\mathrm{t}\\overline{\\mathrm{t}}$$ cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution.« less

Coincidence charged-current neutrino-induced deuteron disintegration for 2H2 16O

NASA Astrophysics Data System (ADS)

Van Orden, J. W.; Donnelly, T. W.; Moreno, O.

2017-12-01

Semi-inclusive charge-changing neutrino reactions on targets of heavy water are investigated with the goal of determining the relative contributions to the total cross section of deuterium and oxygen in kinematics chosen to emphasize the former. The study is undertaken for conditions where the typical neutrino beam energies are in the few GeV region, and hence relativistic modeling is essential. For this, the previous relativistic approach for the deuteron is employed, together with a spectral function approach for the case of oxygen. Upon optimizing the kinematics of the final-state particles assumed to be detected (typically a muon and a proton) it is shown that the oxygen contribution to the total cross section is suppressed by roughly an order of magnitude compared with the deuterium cross section, thereby confirming that CC ν studies of heavy water can effectively yield the cross sections for deuterium, with acceptable backgrounds from oxygen. This opens the possibility of using deuterium to determine the incident neutrino flux distribution, to have it serve as a target for which the nuclear structure issues are minimal, and possibly to use deuterium to provide improved knowledge of specific aspects of hadronic structure, such as to explore the momentum transfer dependence of the isovector axial-vector form factor of the nucleon.

Contemporary trends in dyslipidemia in the Framingham Heart Study

USDA-ARS?s Scientific Manuscript database

Recent cross-sectional population studies in the United States have shown an increase in obesity, a decrease in cholesterol values, but no changes in levels of high-density lipoprotein cholesterol (HDL-C) or triglycerides (TG). Plasma total cholesterol, HDL-C, and TG levels, measured by the same met...

Elevated blood lead and cadmium levels associated with chronic infections among non-smokers in a cross-sectional analysis of NHANES data

EPA Science Inventory

BACKGROUND: Experimental animal studies, in vitro experiments, and clinical assessments have shown that metal toxicity can impair immune responses. We analyzed data from a United States representative National Health and Nutrition Examination Survey (NHANES) to explore associatio...

Perfectionism and Achievement Goal Orientations in Adolescent School Students

ERIC Educational Resources Information Center

Damian, Lavinia E.; Stoeber, Joachim; Negru, Oana; Baban, Adriana

2014-01-01

Perfectionism has been shown to predict individual differences in achievement goal orientations in university students, but research on perfectionism and goal orientations in school students is still very limited. Investigating 584 adolescent school students in a cross-sectional correlational design, the present study examined how self-oriented…

Hospital activity and hospital profits.

PubMed

Hegji, Charles E

2007-01-01

The paper uses data from a cross section of southeastern hospitals to examine which activities are profitable for hospitals. The analysis suggests that hospitals may operate at less than profit-maximizing levels of output. In addition, contrary to popular belief emergency rooms are shown to be profit generating centers for hospitals.

Collective Definition of Practices Causing Dysfunction in Children.

ERIC Educational Resources Information Center

Niehoff, Michael A.

The development of psychopathology stems, in large measure, from antecedent childhood stresses of maltreatment. This paper creates a list of factors that have been shown to lead to dysfunctional behavior. Such a list could be a valuable resource in the prevention and treatment of psychopathological behavior. A comprehensive cross-section of…

Consistent initial conditions for the Saint-Venant equations in river network modeling

NASA Astrophysics Data System (ADS)

Yu, Cheng-Wei; Liu, Frank; Hodges, Ben R.

2017-09-01

Initial conditions for flows and depths (cross-sectional areas) throughout a river network are required for any time-marching (unsteady) solution of the one-dimensional (1-D) hydrodynamic Saint-Venant equations. For a river network modeled with several Strahler orders of tributaries, comprehensive and consistent synoptic data are typically lacking and synthetic starting conditions are needed. Because of underlying nonlinearity, poorly defined or inconsistent initial conditions can lead to convergence problems and long spin-up times in an unsteady solver. Two new approaches are defined and demonstrated herein for computing flows and cross-sectional areas (or depths). These methods can produce an initial condition data set that is consistent with modeled landscape runoff and river geometry boundary conditions at the initial time. These new methods are (1) the pseudo time-marching method (PTM) that iterates toward a steady-state initial condition using an unsteady Saint-Venant solver and (2) the steady-solution method (SSM) that makes use of graph theory for initial flow rates and solution of a steady-state 1-D momentum equation for the channel cross-sectional areas. The PTM is shown to be adequate for short river reaches but is significantly slower and has occasional non-convergent behavior for large river networks. The SSM approach is shown to provide a rapid solution of consistent initial conditions for both small and large networks, albeit with the requirement that additional code must be written rather than applying an existing unsteady Saint-Venant solver.

A clinically oriented comprehensive pictorial review of canine elbow anatomy.

PubMed

Constantinescu, Gheorghe M; Constantinescu, Ileana A

2009-02-01

The clinically oriented canine elbow anatomy in its complexity earned a high importance in surgery especially after multiple imaging modalities have been used in the benefit of diagnosis and treatment of canine elbow disorders. The bony, joint, and muscular structures, the arteries, the veins and the nerves supplying the elbow are described and illustrated in textbooks and atlases in the context of the comparative anatomy. Nevertheless, there is no publication focused on all of these structures described together from the skin to the bones in a systematic and topographic order, nor through cross and/or sagittal and coronal sections. The figures used in this article are original and drawn after dissection, cross, sagittal, and coronal sections of the elbow structures. The sections are correlated to the multiple imaging modalities shown in the next article.

Simulation of unsteady flow and solute transport in a tidal river network

USGS Publications Warehouse

Zhan, X.

2003-01-01

A mathematical model and numerical method for water flow and solute transport in a tidal river network is presented. The tidal river network is defined as a system of open channels of rivers with junctions and cross sections. As an example, the Pearl River in China is represented by a network of 104 channels, 62 nodes, and a total of 330 cross sections with 11 boundary section for one of the applications. The simulations are performed with a supercomputer for seven scenarios of water flow and/or solute transport in the Pearl River, China, with different hydrological and weather conditions. Comparisons with available data are shown. The intention of this study is to summarize previous works and to provide a useful tool for water environmental management in a tidal river network, particularly for the Pearl River, China.

Modeling spanwise nonuniformity in the cross-sectional analysis of composite beams

NASA Astrophysics Data System (ADS)

Ho, Jimmy Cheng-Chung

Spanwise nonuniformity effects are modeled in the cross-sectional analysis of beam theory. This modeling adheres to an established numerical framework on cross-sectional analysis of uniform beams with arbitrary cross-sections. This framework is based on two concepts: decomposition of the rotation tensor and the variational-asymptotic method. Allowance of arbitrary materials and geometries in the cross-section is from discretization of the warping field by finite elements. By this approach, dimensional reduction from three-dimensional elasticity is performed rigorously and the sectional strain energy is derived to be asymptotically-correct. Elastic stiffness matrices are derived for inputs into the global beam analysis. Recovery relations for the displacement, stress, and strain fields are also derived with care to be consistent with the energy. Spanwise nonuniformity effects appear in the form of pointwise and sectionwise derivatives, which are approximated by finite differences. The formulation also accounts for the effects of spanwise variations in initial twist and/or curvature. A linearly tapered isotropic strip is analyzed to demonstrate spanwise nonuniformity effects on the cross-sectional analysis. The analysis is performed analytically by the variational-asymptotic method. Results from beam theory are validated against solutions from plane stress elasticity. These results demonstrate that spanwise nonuniformity effects become significant as the rate at which the cross-sections vary increases. The modeling of transverse shear modes of deformation is accomplished by transforming the strain energy into generalized Timoshenko form. Approximations in this transformation procedure from previous works, when applied to uniform beams, are identified. The approximations are not used in the present work so as to retain more accuracy. Comparison of present results with those previously published shows that these approximations sometimes change the results measurably and thus are inappropriate. Static and dynamic results, from the global beam analysis, are calculated to show the differences between using stiffness constants from previous works and the present work. As a form of validation of the transformation procedure, calculations from the global beam analysis of initially twisted isotropic beams from using curvilinear coordinate axes featuring twist are shown to be equivalent to calculations using Cartesian coordinates.

Simultaneous measurement of (n,{gamma}) and (n,fission) cross sections with the DANCE 4{pi} BaF2 array

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

Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.

2006-03-13

Neutron capture cross section measurements on many of the actinides are complicated by low-energy neutron-induced fission, which competes with neutron capture to varying degrees depending on the nuclide of interest. Measurements of neutron capture on 235U using the Detector for Advanced Neutron Capture Experiments (DANCE) have shown that we can partially resolve capture from fission events based on total photon calorimetry (i.e. total {gamma}-ray energy and {gamma}-ray multiplicity per event). The addition of a fission-tagging detector to the DANCE array will greatly improve our ability to separate these two competing processes so that improved neutron capture and (n,{gamma})/(n,fission) cross sectionmore » ratio measurements can be obtained. The addition of a fission-tagging detector to the DANCE array will also provide a means to study several important issues associated with neutron-induced fission, including (n,fission) cross sections as a function of incident neutron energy, and total energy and multiplicity of prompt fission photons. We have focused on two detector designs with complementary capabilities, a parallel-plate avalanche counter and an array of solar cells.« less

Designing an upgrade of the Medley setup for light-ion production and fission cross-section measurements

NASA Astrophysics Data System (ADS)

Jansson, K.; Gustavsson, C.; Al-Adili, A.; Hjalmarsson, A.; Andersson-Sundén, E.; Prokofiev, A. V.; Tarrío, D.; Pomp, S.

2015-09-01

Measurements of neutron-induced fission cross-sections and light-ion production are planned in the energy range 1-40 MeV at the upcoming Neutrons For Science (NFS) facility. In order to prepare our detector setup for the neutron beam with continuous energy spectrum, a simulation software was written using the Geant4 toolkit for both measurement situations. The neutron energy range around 20 MeV is troublesome when it comes to the cross-sections used by Geant4 since data-driven cross-sections are only available below 20 MeV but not above, where they are based on semi-empirical models. Several customisations were made to the standard classes in Geant4 in order to produce consistent results over the whole simulated energy range. Expected uncertainties are reported for both types of measurements. The simulations have shown that a simultaneous precision measurement of the three standard cross-sections H(n,n), 235U(n,f) and 238U(n,f) relative to each other is feasible using a triple layered target. As high resolution timing detectors for fission fragments we plan to use Parallel Plate Avalanche Counters (PPACs). The simulation results have put some restrictions on the design of these detectors as well as on the target design. This study suggests a fissile target no thicker than 2 μm (1.7 mg/cm2) and a PPAC foil thickness preferably less than 1 μm. We also comment on the usability of Geant4 for simulation studies of neutron reactions in this energy range.

Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability.

PubMed

Appelquist, T; Berkowitz, E; Brower, R C; Buchoff, M I; Fleming, G T; Jin, X-Y; Kiskis, J; Kribs, G D; Neil, E T; Osborn, J C; Rebbi, C; Rinaldi, E; Schaich, D; Schroeder, C; Syritsyn, S; Vranas, P; Weinberg, E; Witzel, O

2015-10-23

We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar "stealth baryon" dark matter candidate, arising from a dark SU(4) confining gauge theory-"stealth dark matter." In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest "baryon" states in SU(3) and SU(4) gauge theories using the background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N) groups. The resulting scattering cross sections with a xenon target are shown to be potentially detectable in the dark matter mass range of about 200-700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1/m(B)(6), suggests the observable dark matter mass range is not appreciably modified. We briefly highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter.

Supplier-induced demand: re-examining identification and misspecification in cross-sectional analysis.

PubMed

Peacock, Stuart J; Richardson, Jeffrey R J

2007-09-01

This paper re-examines criticisms of cross-sectional methods used to test for supplier-induced demand (SID) and re-evaluates the empirical evidence using data from Australian medical services. Cross-sectional studies of SID have been criticised on two grounds. First, and most important, the inclusion of the doctor supply in the demand equation leads to an identification problem. This criticism is shown to be invalid, as the doctor supply variable is stochastic and depends upon a variety of other variables including the desirability of the location. Second, cross-sectional studies of SID fail diagnostic tests and produce artefactual findings due to model misspecification. Contrary to this, the re-evaluation of cross-sectional Australian data indicate that demand equations that do not include the doctor supply are misspecified. Empirical evidence from the re-evaluation of Australian medical services data supports the notion of SID. Demand and supply equations are well specified and have very good explanatory power. The demand equation is identified and the desirability of a location is an important predictor of the doctor supply. Results show an average price elasticity of demand of 0.22 and an average elasticity of demand with respect to the doctor supply of 0.46, with the impact of SID becoming stronger as the doctor supply rises. The conclusion we draw from this paper is that two of the main criticisms of the empirical evidence supporting the SID hypothesis have been inappropriately levelled at the methods used. More importantly, SID provides a satisfactory, and robust, explanation of the empirical data on the demand for medical services in Australia.

Contribution of inner shell Compton ionization to the X-ray fluorescence line intensity

NASA Astrophysics Data System (ADS)

Fernández, Jorge E.; Scot, Viviana; Di Giulio, Eugenio

2016-10-01

The Compton effect is a potential ionization mechanism of atoms. It produces vacancies in inner shells that are filled with the same mechanism of atomic relaxation as the one following photo-absorption. This contribution to X-ray fluorescence emission is frequently neglected because the total Compton cross-section is apparently much lower than the photoelectric one at useful X-ray energies. However, a more careful analysis suggests that is necessary to consider single shell cross sections (instead of total cross sections) as a function of energy. In this article these Compton cross sections are computed for the shells K, L1-L3 and M1-M5 in the framework of the impulse approximation. By comparing the Compton and the photoelectric cross-section for each shell it is then possible to determine the extent of the Compton correction to the intensity of the corresponding characteristic lines. It is shown that for the K shell the correction becomes relevant for excitation energies which are too high to be influent in X-ray spectrometry. In contrast, for L and M shells the Compton contribution is relevant for medium-Z elements and medium energies. To illustrate the different grades of relevance of the correction, for each ionized shell, the energies for which the Compton contribution reaches the extent levels of 1, 5, 10, 20, 50 and 100% of the photoelectric one are determined for all the elements with Z = 11-92. For practical applications it is provided a simple formula and fitting coefficients to compute average correction levels for the shells considered.

Rate processes in gas phase

NASA Technical Reports Server (NTRS)

Hansen, C. F.

1983-01-01

Reaction-rate theory and experiment are given a critical review from the engineers' point of view. Rates of heavy-particle, collision-induced reaction in gas phase are formulated in terms of the cross sections and activation energies for reaction. The effect of cross section function shape and of excited state contributions to reaction both cause the slope of Arrhenius plots to differ from the true activation energy, except at low temperature. The master equations for chemically reacting gases are introduced, and dissociation and ionization reactions are shown to proceed primarily from excited states about kT from the dissociation or ionization limit. Collision-induced vibration, vibration-rotation, and pure rotation transitions are treated, including three-dimensional effects and conservation of energy, which have usually been ignored. The quantum theory of transitions at potential surface crossing is derived, and results are found to be in fair agreement with experiment in spite of some questionable approximations involved.

Energy levels of a quantum particle on a cylindrical surface with non-circular cross-section in electric and magnetic fields

NASA Astrophysics Data System (ADS)

Cruz, Philip Christopher S.; Bernardo, Reginald Christian S.; Esguerra, Jose Perico H.

2017-04-01

We calculate the energy levels of a quantum particle on a cylindrical surface with non-circular cross-section in uniform electric and magnetic fields. Using separation of variables method and a change of independent variable, we show that the problem can be reduced to a one-dimensional Schrödinger equation for a periodic potential. The effects of varying the shape of the cross-section while keeping the same perimeter and the strengths of the electric and magnetic fields are investigated for elliptical, corrugated, and nearly-rectangular tubes with radial dimensions of the order of a nanometer. The geometric potential has minima at the angular positions where there is a significant amount of curvature. For the elliptical and corrugated tubes, it is shown that as the tube departs from the circular shape of cross-section the double-degeneracy between the energy levels is lifted. For the nearly-rectangular tube, it is shown that energy level crossings occur as the horizontal dimension of the tube is varied while keeping the same perimeter and radius of circular corners. The interplay between the curvature and the strength of the electric and magnetic fields determines the overall behavior of the energy levels. As the strength of the electric field increases, the overall potential gets skewed creating a potential well on the side corresponding to the more negative electric potential. The energy levels of the first few excited states approach more positive values while the ground state energy level approaches a more negative value. For large electric fields, all bound state energy levels tend to more negative values. The contribution of weak magnetic fields to the overall potential behaves in the same way as the electric field contribution but with its sign depending on the direction of the component of the momentum parallel to the cylindrical axis. Large magnetic fields lead to pairing of energy levels reminiscent of 2D Landau levels for the elliptical and nearly-rectangular tubes.

Energy levels of a quantum particle on a cylindrical surface with non-circular cross-section in electric and magnetic fields

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

Cruz, Philip Christopher S., E-mail: pscruz1@up.edu.ph; Bernardo, Reginald Christian S., E-mail: rcbernardo@nip.upd.edu.ph; Esguerra, Jose Perico H., E-mail: jesguerra@nip.upd.edu.ph

We calculate the energy levels of a quantum particle on a cylindrical surface with non-circular cross-section in uniform electric and magnetic fields. Using separation of variables method and a change of independent variable, we show that the problem can be reduced to a one-dimensional Schrödinger equation for a periodic potential. The effects of varying the shape of the cross-section while keeping the same perimeter and the strengths of the electric and magnetic fields are investigated for elliptical, corrugated, and nearly-rectangular tubes with radial dimensions of the order of a nanometer. The geometric potential has minima at the angular positions wheremore » there is a significant amount of curvature. For the elliptical and corrugated tubes, it is shown that as the tube departs from the circular shape of cross-section the double-degeneracy between the energy levels is lifted. For the nearly-rectangular tube, it is shown that energy level crossings occur as the horizontal dimension of the tube is varied while keeping the same perimeter and radius of circular corners. The interplay between the curvature and the strength of the electric and magnetic fields determines the overall behavior of the energy levels. As the strength of the electric field increases, the overall potential gets skewed creating a potential well on the side corresponding to the more negative electric potential. The energy levels of the first few excited states approach more positive values while the ground state energy level approaches a more negative value. For large electric fields, all bound state energy levels tend to more negative values. The contribution of weak magnetic fields to the overall potential behaves in the same way as the electric field contribution but with its sign depending on the direction of the component of the momentum parallel to the cylindrical axis. Large magnetic fields lead to pairing of energy levels reminiscent of 2D Landau levels for the elliptical and nearly-rectangular tubes.« less

On the Locality of Transient Electromagnetic Soundings with a Single-Loop Configuration

NASA Astrophysics Data System (ADS)

Barsukov, P. O.; Fainberg, E. B.

2018-03-01

The possibilities of reconstructing two-dimensional (2D) cross sections based on the data of the profile soundings by the transient electromagnetic method (TEM) with a single ungrounded loop are illustrated on three-dimensional (3D) models. The process of reconstruction includes three main steps: transformation of the responses in the depth dependence of resistivity ρ(h) measured along the profile, with their subsequent stitching into the 2D pseudo section; point-by-point one-dimensional (1D) inversion of the responses with the starting model constructed based on the transformations; and correction of the 2D cross section with the use of 2.5-dimensional (2.5D) block inversion. It is shown that single-loop TEM soundings allow studying the geological media within a local domain the lateral dimensions of which are commensurate with the depth of the investigation. The structure of the medium beyond this domain insignificantly affects the sounding results. This locality enables the TEM to reconstruct the geoelectrical structure of the medium from the 2D cross sections with the minimal distortions caused by the lack of information beyond the profile of the transient response measurements.

Evaluation of computational models and cross sections used by MCNP6 for simulation of characteristic X-ray emission from thick targets bombarded by kiloelectronvolt electrons

NASA Astrophysics Data System (ADS)

Poškus, A.

2016-09-01

This paper evaluates the accuracy of the single-event (SE) and condensed-history (CH) models of electron transport in MCNP6.1 when simulating characteristic Kα, total K (=Kα + Kβ) and Lα X-ray emission from thick targets bombarded by electrons with energies from 5 keV to 30 keV. It is shown that the MCNP6.1 implementation of the CH model for the K-shell impact ionization leads to underestimation of the K yield by 40% or more for the elements with atomic numbers Z < 15 and overestimation of the Kα yield by more than 40% for the elements with Z > 25. The Lα yields are underestimated by more than an order of magnitude in CH mode, because MCNP6.1 neglects X-ray emission caused by electron-impact ionization of L, M and higher shells in CH mode (the Lα yields calculated in CH mode reflect only X-ray fluorescence, which is mainly caused by photoelectric absorption of bremsstrahlung photons). The X-ray yields calculated by MCNP6.1 in SE mode (using ENDF/B-VII.1 library data) are more accurate: the differences of the calculated and experimental K yields are within the experimental uncertainties for the elements C, Al and Si, and the calculated Kα yields are typically underestimated by (20-30)% for the elements with Z > 25, whereas the Lα yields are underestimated by (60-70)% for the elements with Z > 49. It is also shown that agreement of the experimental X-ray yields with those calculated in SE mode is additionally improved by replacing the ENDF/B inner-shell electron-impact ionization cross sections with the set of cross sections obtained from the distorted-wave Born approximation (DWBA), which are also used in the PENELOPE code system. The latter replacement causes a decrease of the average relative difference of the experimental X-ray yields and the simulation results obtained in SE mode to approximately 10%, which is similar to accuracy achieved with PENELOPE. This confirms that the DWBA inner-shell impact ionization cross sections are significantly more accurate than the corresponding ENDF/B cross sections when energy of incident electrons is of the order of the binding energy.

Pricing behavior of non-profit agencies. The case of blood products.

PubMed

Jacobs, P; Wilder, R P

1984-04-01

In this study we examine the pricing behavior of a non-profit agency, the American National Red Cross blood service units. Two alternative hypotheses are presented: one in which the agency maximizes profits,, and one in which output is maximized subject to a breakeven constraint. Following a general approach developed by Eckstein and Fromm , pricing equations for separate blood products are applied to cross-sectional data from Red Cross blood centers to determine the impact of demand, cost, competition, and subsidy variables. The impact of these variables, in particular the impact of the fixed subsidy on price, is shown to be consistent with the output-maximizing model.

On the Relation Between Spherical Harmonics and Simplified Spherical Harmonics Methods

NASA Astrophysics Data System (ADS)

Coppa, G. G. M.; Giusti, V.; Montagnini, B.; Ravetto, P.

2010-03-01

The purpose of the paper is, first, to recall the proof that the AN method and, therefore, the SP2N-1 method (of which AN was shown to be a variant) are equivalent to the odd order P2N-1, at least for a particular class of multi-region problems; namely the problems for which the total cross section has the same value for all the regions and the scattering is supposed to be isotropic. By virtue of the introduction of quadrature formulas representing first collision probabilities, this class is then enlarged in order to encompass the systems in which the regions may have different total cross sections. Some examples are reported to numerically validate the procedure.

Parallel programming of gradient-based iterative image reconstruction schemes for optical tomography.

PubMed

Hielscher, Andreas H; Bartel, Sebastian

2004-02-01

Optical tomography (OT) is a fast developing novel imaging modality that uses near-infrared (NIR) light to obtain cross-sectional views of optical properties inside the human body. A major challenge remains the time-consuming, computational-intensive image reconstruction problem that converts NIR transmission measurements into cross-sectional images. To increase the speed of iterative image reconstruction schemes that are commonly applied for OT, we have developed and implemented several parallel algorithms on a cluster of workstations. Static process distribution as well as dynamic load balancing schemes suitable for heterogeneous clusters and varying machine performances are introduced and tested. The resulting algorithms are shown to accelerate the reconstruction process to various degrees, substantially reducing the computation times for clinically relevant problems.

Measurement of the cross section and longitudinal double-spin asymmetry for dijet production in polarized p p collisions at √{s }=200 GeV

NASA Astrophysics Data System (ADS)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Ajitanand, N. N.; Alekseev, I.; Anderson, D. M.; Aoyama, R.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Barish, K.; Behera, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Brown, D.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chankova-Bunzarova, N.; Chatterjee, A.; Chattopadhyay, S.; Chen, X.; Chen, X.; Chen, J. H.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Elsey, N.; Engelage, J.; Eppley, G.; Esha, R.; Esumi, S.; Evdokimov, O.; Ewigleben, J.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Federicova, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Fujita, J.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Harlenderova, A.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, B.; Huang, H. Z.; Huang, X.; Humanic, T. J.; Huo, P.; Igo, G.; Jacobs, W. W.; Jentsch, A.; Jia, J.; Jiang, K.; Jowzaee, S.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kapukchyan, D.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z.; Kikoła, D. P.; Kim, C.; Kisel, I.; Kisiel, A.; Kochenda, L.; Kocmanek, M.; Kollegger, T.; Kosarzewski, L. K.; Kraishan, A. F.; Krauth, L.; Kravtsov, P.; Krueger, K.; Kulathunga, N.; Kumar, L.; Kvapil, J.; Kwasizur, J. H.; Lacey, R.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, W.; Li, C.; Li, Y.; Li, X.; Lidrych, J.; Lin, T.; Lisa, M. A.; Liu, H.; Liu, F.; Liu, Y.; Liu, P.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Luo, S.; Ma, R.; Ma, G. L.; Ma, L.; Ma, Y. G.; Magdy, N.; Majka, R.; Mallick, D.; Margetis, S.; Markert, C.; Matis, H. S.; Meehan, K.; Mei, J. C.; Miller, Z. W.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mizuno, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nie, M.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Nonaka, T.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Ray, R. L.; Reed, R.; Rehbein, M. J.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roth, J. D.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Salur, S.; Sandweiss, J.; Saur, M.; Schambach, J.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Schweid, B. R.; Seger, J.; Sergeeva, M.; Seto, R.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, A.; Sharma, M. K.; Shen, W. Q.; Shi, S. S.; Shi, Z.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Strikhanov, M.; Stringfellow, B.; Sugiura, T.; Sumbera, M.; Summa, B.; Sun, X.; Sun, X. M.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, A. H.; Tang, Z.; Taranenko, A.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vasiliev, A. N.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, G.; Wang, Y.; Wang, F.; Wang, Y.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Xu, Z.; Xu, J.; Yang, Y.; Yang, S.; Yang, C.; Yang, Q.; Ye, Z.; Ye, Z.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, S.; Zhang, J. B.; Zhang, Y.; Zhang, J.; Zhang, J.; Zhang, S.; Zhang, X. P.; Zhang, Z.; Zhao, J.; Zhong, C.; Zhou, C.; Zhou, L.; Zhu, Z.; Zhu, X.; Zyzak, M.; STAR Collaboration

2017-04-01

We report the first measurement of the longitudinal double-spin asymmetry AL L for midrapidity dijet production in polarized p p collisions at a center-of-mass energy of √{s }=200 GeV . The dijet cross section was measured and is shown to be consistent with next-to-leading order (NLO) perturbative QCD predictions. AL L results are presented for two distinct topologies, defined by the jet pseudorapidities, and are compared to predictions from several recent NLO global analyses. The measured asymmetries, the first such correlation measurements, support those analyses that find positive gluon polarization at the level of roughly 0.2 over the region of Bjorken-x >0.05 .

The relation of trait and state mindfulness with satisfaction and physical activity: A cross-sectional study in 305 Dutch participants.

PubMed

Tsafou, Kalliopi-Eleni; Lacroix, Joyca Pw; van Ee, Raymond; Vinkers, Charlotte Dw; De Ridder, Denise Td

2017-09-01

Previous research has shown that satisfaction mediates the relationship of state mindfulness (i.e. during physical activity) with physical activity. This study aimed to replicate this finding and to explore the role of trait mindfulness with a cross-sectional design. In all, 305 participants completed measures on trait and state mindfulness, satisfaction with physical activity, and physical activity. Mediation analyses were used. Satisfaction mediated the effect of state mindfulness on physical activity. Trait mindfulness related to physical activity via an indirect path, namely through two consecutive mediators, first state mindfulness and then satisfaction. Our results suggest that to enhance satisfaction, both state and trait mindfulness should be considered.

Criteria for applicability of the impulse approach to collisions

NASA Astrophysics Data System (ADS)

Sharma, Ramesh D.; Bakshi, Pradip M.; Sindoni, Joseph M.

1990-06-01

Using an exact formulation of impulse approach (IA) to atom-diatom collisions, we assess its internal consistency. By comparing the cross sections in the forward and reverse directions for the vibrational-rotational inelastic processes, using the half-on-the-shell (post and prior) models of the two-body t matrix, we show that in both cases the IA leads to a violation of the semidetailed balance (SDB) condition for small scattering angles. An off-shell model for the two-body t matrix, which preserves SDB, is shown to have other serious shortcomings. The cross sections are studied quantitatively as a function of the relative translational energy and the mass of the incident particle, and criteria discussed for the applicability of IA.

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

Sharma, R.D.; Bakshi, P.M.; Sindoni, J.M.

Using an exact formulation of impulse approach (IA) to atom-diatom collisions, we assess its internal consistency. By comparing the cross sections in the forward and reverse directions for the vibrational-rotational inelastic processes, using the half-on-the-shell (post and prior) models of the two-body {ital t} matrix, we show that in both cases the IA leads to a violation of the semidetailed balance (SDB) condition for small scattering angles. An off-shell model for the two-body {ital t} matrix, which preserves SDB, is shown to have other serious shortcomings. The cross sections are studied quantitatively as a function of the relative translational energymore » and the mass of the incident particle, and criteria discussed for the applicability of IA.« less

FIBER AND INTEGRATED OPTICS. OPTOELECTRONICS: Method for calculation of the parameters of guided waves in anisotropic dielectric waveguides

NASA Astrophysics Data System (ADS)

Goncharenko, I. A.

1989-07-01

The method of shift formulas is applied to anisotropic dielectric waveguides capable of conserving a given state of polarization of the transmitted signal. Equations are derived for calculation of the propagation constants and of the dispersion of the fundamental modes in waveguides with an anisotropic permittivity and a noncircular shape of the transverse cross section. Distributions of electric and magnetic fields of these modes are obtained in a transverse cross section of the waveguide. It is shown that under the influence of the anisotropy of the dielectric an energy spot describing the distribution of the mode field becomes of an ellipse with its axes oriented along the coordinates coinciding with the principal axes of the permittivity tensor.

Dynamic analysis of pretwisted elastically-coupled rotor blades

NASA Technical Reports Server (NTRS)

Nixon, Mark W.; Hinnant, Howard E.

1994-01-01

The accuracy of using a one-dimensional analysis to predict frequencies of elastically-coupled highly-twisted rotor blades is addressed. Degrees of freedom associated with shear deformation are statically condensed from the formulation, so the analysis uses only those degrees of freedom associated with classical beam theory. The effects of cross section deformation (warping) are considered, and are shown to become significant for some types of elastic coupling. Improved results are demonstrated for highly-coupled blade structures through account of warping in a local cross section analysis, without explicit inclusion of these effects in the beam analysis. A convergence study is also provided which investigates the potential for improving efficiency of elastically-coupled beam analysis through implementation of a p-version beam finite element.

Nuclear structure and reaction properties of Ne, Mg and Si isotopes with RMF densities

NASA Astrophysics Data System (ADS)

Panda, R. N.; Sharma, Mahesh K.; Patra, S. K.

2014-01-01

We have studied nuclear structure and reaction properties of Ne, Mg and Si isotopes, using relativistic mean field (RMF) densities, in the framework of Glauber model. Total reaction cross-section σR for Ne isotopes on 12C target have been calculated at incident energy 240 MeV. The results are compared with the experimental data and with the recent theoretical study [W. Horiuchi et al., Phys. Rev. C 86, 024614 (2012)]. Study of σR using deformed densities have shown a good agreement with the data. We have also predicted total reaction cross-section σR for Ne, Mg and Si isotopes as projectiles and 12C as target at different incident energies.

Semihard processes with BLM renormalization scale setting

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

Caporale, Francesco; Ivanov, Dmitry Yu.; Murdaca, Beatrice

We apply the BLM scale setting procedure directly to amplitudes (cross sections) of several semihard processes. It is shown that, due to the presence of β{sub 0}-terms in the NLA results for the impact factors, the obtained optimal renormalization scale is not universal, but depends both on the energy and on the process in question. We illustrate this general conclusion considering the following semihard processes: (i) inclusive production of two forward high-p{sub T} jets separated by large interval in rapidity (Mueller-Navelet jets); (ii) high-energy behavior of the total cross section for highly virtual photons; (iii) forward amplitude of the productionmore » of two light vector mesons in the collision of two virtual photons.« less

Measurement of the radiative capture cross section of the s-process branching points 204Tl and 171Tm at the n_TOF facility (CERN)

NASA Astrophysics Data System (ADS)

Casanovas, A.; Domingo-Pardo, C.; Guerrero, C.; Lerendegui-Marco, J.; Calviño, F.; Tarifeño-Saldivia, A.; Dressler, R.; Heinitz, S.; Kivel, N.; Quesada, J. M.; Schumann, D.; Aberle, O.; Alcayne, V.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bacak, M.; Barbagallo, M.; Bečvář, F.; Bellia, G.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brown, A.; Busso, M.; Caamaño, M.; Caballero-Ontanaya, L.; Calviani, M.; Cano-Ott, D.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Cristallo, S.; Damone, L. A.; Diakaki, M.; Dietz, M.; Dupont, E.; Durán, I.; Eleme, Z.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Furman, V.; Göbel, K.; Gawlik, A.; Gilardoni, S.; Glodariu, T.; Gonçalves, I. F.; González-Romero, E.; Gunsing, F.; Heyse, J.; Jenkins, D. G.; Käppeler, F.; Kadi, Y.; Katabuchi, T.; Kimura, A.; Kokkoris, M.; Kopatch, Y.; Krtička, M.; Kurtulgil, D.; Ladarescu, I.; Lederer-Woods, C.; Meo, S. Lo; Lonsdale, S. J.; Macina, D.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Matteucci, F.; Maugeri, E. A.; Mazzone, A.; Mendoza, E.; Mengoni, A.; Michalopoulou, V.; Milazzo, P. M.; Mingrone, F.; Musumarra, A.; Negret, A.; Nolte, R.; Ogállar, F.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Persanti, L.; Porras, I.; Praena, J.; Radeck, D.; Ramos, D.; Rauscher, T.; Reifarth, R.; Rochman, D.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Simone, S.; Smith, A. G.; Sosnin, N. V.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Talip, T.; Tassan-Got, L.; Tsinganis, A.; Ulrich, J.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Woods, P. J.; Wright, T.; Žugec, P.; Köster, U.

2018-05-01

The neutron capture cross section of some unstable nuclei is especially relevant for s-process nucleosynthesis studies. This magnitude is crucial to determine the local abundance pattern, which can yield valuable information of the s-process stellar environment. In this work we describe the neutron capture (n,γ) measurement on two of these nuclei of interest, 204Tl and 171Tm, from target production to the final measurement, performed successfully at the n_TOF facility at CERN in 2014 and 2015. Preliminary results on the ongoing experimental data analysis will also be shown. These results include the first ever experimental observation of capture resonances for these two nuclei.

Emotion Regulation in Adolescence: A Prospective Study of Expressive Suppression and Depressive Symptoms

ERIC Educational Resources Information Center

Larsen, Junilla K.; Vermulst, Ad A.; Geenen, Rinie; van Middendorp, Henriet; English, Tammy; Gross, James J.; Ha, Thao; Evers, Catharine; Engels, Rutger C. M. E.

2013-01-01

Cross-sectional studies have shown a positive association between expressive suppression and depressive symptoms. These results have been interpreted as reflecting the impact of emotion regulation efforts on depression. However, it is also possible that depression may alter emotion regulation tendencies. The goal of the present study was to…

Empathy and Coping Strategies as Predictors of Well-Being in Spanish University Students

ERIC Educational Resources Information Center

Carnicer, Josep Gustems; Calderón, Caterina

2014-01-01

Introduction: Empathy and coping strategies have been shown to be closely associated with the perceived psychological well-being of students. The aim of the present study was to analyze the relationship between empathy and coping strategies and psychological distress among students in teacher education. Method: A cross-sectional study. Ninety…

Top Quark Properties at Tevatron

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

Lysák, Roman

2017-11-27

The latest CDF and D0 experiment measurements of the top quark properties except the top quark mass are presented. The final combination of the CDF and D0 forward-backward asymmetry measurements is shown together with the D0 measurements of the inclusive top quark pair cross-section as well as the top quark polarization.

Spectral peculiarities of electromagnetic wave scattering by Veselago's cylinders

NASA Astrophysics Data System (ADS)

Sukhov, S. V.; Shevyakhov, N. S.

2006-03-01

The results are presented of spectral calculations of extinction cross-section for scattering of E- and H-polarized electromagnetic waves by cylinders made of Veselago material. The insolvency of previously developed models of scattering is demonstrated. It is shown that correct description of scattering requires separate consideration of both electric and magnetic subsystems.

Spectral peculiarities of electromagnetic wave scattered by Veselago's cylinders

NASA Astrophysics Data System (ADS)

Sukhov, S. V.; Shevyakhov, N. S.

2005-09-01

The results are presented of spectral calculations of extinction cross-section for scattering of E- and H-polarized electromagnetic waves by cylinders made of Veselago material. The insolvency of previously developed models of scattering is demonstrated. It is shown that correct description of scattering requires separate consideration of both electric and magnetic subsystems.

Modern Kaleidophones

ERIC Educational Resources Information Center

Daffron, John A.; Greenslade, Thomas B., Jr.

2015-01-01

The Kaleidophone, invented by Charles Wheatstone (1802-1875) in 1827, is a delightful mixture of physics and art. A typical example of the device, dating from the latter part of the 19th century, is shown in Fig. 1. The upright rods, which are approximately 25 cm in length, are of variously circular, oval, square, and rectangular cross section,…

Developmental Trajectories of Bullying and Social Dominance in Youth

ERIC Educational Resources Information Center

Reijntjes, Albert; Vermande, Marjolijn; Goossens, Frits A.; Olthof, Tjeert; van de Schoot, Rens; Aleva, Liesbeth; van der Meulen, Matty

2013-01-01

Objective: Bullying is increasingly conceptualized as strategic behavior motivated by a desire to gain social dominance in the peer group. Cross-sectional research has shown that relative to their peers bullies are higher in social dominance as indexed by resource control, and are often perceived as powerful and "cool." However, research examining…

Fruit and vegetable attitudes, norms, and intake in low-income youth

USDA-ARS?s Scientific Manuscript database

Fruit and vegetable (FV) attitudes and norms have been shown to influence intake in youth; yet research with low-income youth and studies supplementing self-report with objective measures of intake are lacking. Cross-sectional survey data on self-rated FV intake, FV attitudes, and FV norms were coll...

Profiling of the injected charge drift current transients by cross-sectional scanning technique

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

Gaubas, E., E-mail: eugenijus.gaubas@ff.vu.lt; Ceponis, T.; Pavlov, J.

2014-02-07

The electric field distribution and charge drift currents in Si particle detectors are analyzed. Profiling of the injected charge drift current transients has been implemented by varying charge injection position within a cross-sectional boundary of the particle detector. The obtained profiles of the induction current density and duration of the injected charge drift pulses fit well the simulated current variations. Induction current transients have been interpreted by different stages of the bipolar and monopolar drift of the injected carriers. Profiles of the injected charge current transients registered in the non-irradiated and neutron irradiated Si diodes are compared. It has beenmore » shown that the mixed regime of the competing processes of drift, recombination, and diffusion appears in the measured current profiles on the irradiated samples. The impact of the avalanche effects can be ignored based on the investigations presented. It has been shown that even a simplified dynamic model enabled us to reproduce the main features of the profiled transients of induced charge drift current.« less

ASYMMETRIC ABSORPTION PROFILES OF Ly{alpha} AND Ly{beta} IN DAMPED Ly{alpha} SYSTEMS

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

Lee, Hee-Won, E-mail: hwlee@sejong.ac.kr

2013-08-01

Damped Ly{alpha} systems observed in the quasar spectra are characterized by a high neutral hydrogen column density, N{sub HI} > 2 x 10{sup 20} cm{sup -2}. The absorption wing profiles are often fitted using the Voigt function due to the fact that the scattering cross section near the resonant line center is approximately described by the Lorentzian function. Since a hydrogen atom has infinitely many p states that participate in the electric dipole interaction, the cross section starts to deviate from the Lorentzian in an asymmetric way in the line wing regions. We investigate this asymmetry in the absorption linemore » profiles around Ly{alpha} and Ly{beta} as a function of the neutral hydrogen column density N{sub HI}. In terms of {Delta}{lambda} {identical_to} {lambda} - {lambda}{sub {alpha}}, we expand the Kramers-Heisenberg formula around Ly{alpha} to find {sigma}({lambda}) {approx_equal} (0.5f{sub 12}){sup 2}{sigma}{sub T}({Delta}{lambda}/{lambda}{sub {alpha}}){sup -2}[1 + 3.792({Delta}{lambda}/{lambda}{sub {alpha}})], where f{sub 12} and {sigma}{sub T} are the oscillator strength of Ly{alpha} and the Thomson scattering cross section, respectively. In terms of {Delta}{lambda}{sub 2} {identical_to} {lambda} - {lambda}{sub {beta}} in the vicinity of Ly{beta}, the total scattering cross section, given as the sum of cross sections for Rayleigh and Raman scattering, is shown to be {sigma}({lambda}) {approx_equal} {sigma}{sub T}(0.5f{sub 13}){sup 2}(1 + R{sub 0})({Delta}{lambda}{sub 2}/{lambda}{sub {beta}}){sup -2}[1 - 24.68({Delta}{lambda}{sub 2}/{lambda}{sub {beta}})] with f{sub 13} and the factor R{sub 0} = 0.1342 being the oscillator strength for Ly{beta} and the ratio of the Raman cross section to Rayleigh cross section, respectively. A redward asymmetry develops around Ly{alpha}, whereas a blue asymmetry is obtained for Ly{beta}. The absorption center shifts are found to be almost proportional to the neutral hydrogen column density.« less

Inelastic scattering of electrons at real metal surfaces

NASA Astrophysics Data System (ADS)

Ding, Z.-J.

1997-04-01

A theory is presented to calculate the electron inelastic scattering cross section for a moving electron near the surface region at an arbitrary takeoff angle. The theory is based on using a bulk plasmon-pole approximation to derive the numerically computable expression of the electron self-energy in the random-phase approximation for a surface system, through the use of experimental optical constants. It is shown that the wave-vector-dependent surface dielectric function satisfies the surface sum rules in this scheme. The theory provides a detailed knowledge of electron self-energy depending on the kinetic energy, distance from surface, and velocity vector of an electron moving in any metal of a known dielectric constant, accommodating the formulation to practical situation in surface electron spectroscopies. Numerical computations of the energy-loss cross section have been made for Si and Au. The contribution to the total differential scattering cross section from each component is analyzed. The depth dependence informs us in detail how the bulk excitation mode changes to a surface excitation mode with an electron approaching the surface from the interior of a medium.

Regional stratigraphic cross sections of Cretaceous rocks from east-central Arizona to the Oklahoma Panhandle

USGS Publications Warehouse

Molenaar, C.M.; Cobban, W.A.; Merewether, E.A.; Pillmore, C.L.; Wolfe, D.G.; Holbrook, J.M.

2002-01-01

Sedimentary rocks of Cretaceous age along Transect DD'' in eastern Arizona, northern New Mexico, southern Colorado, and western Oklahoma consist mainly of sandstone, siltstone, shale, limestone, and bentonite. They accumulated as sediments in continental, nearshore marine, and offshore marine environments on the west side of a north-trending epicontinental sea. The rocks record intermittent deposition and erosion as well as regional and local subsidence and uplift possibly beginning in Aptian time (about 121-112 Ma) and occurring in Albian through Maastrichtian time (about 112-65.4 Ma). Most of the Lower Cretaceous (Berriasian through Aptian, 142-112 Ma) in this transect is represented by a basal unconformity. The Cretaceous rocks and unconformities along the transect are depicted on the attached lithostratigraphic cross sections (sheets 1 and 2); one extending from the Mogollon Rim in eastern Arizona to Pagosa Springs in southwestern Colorado and the other from Pagosa Springs, Colorado, to Kenton in western Oklahoma. The same rocks and unconformities are also represented on the attached chronostratigraphic profile (sheet 3), which was prepared mainly from surface and subsurface data shown on the lithostratigraphic cross sections.

extrap: Software to assist the selection of extrapolation methods for moving-boat ADCP streamflow measurements

NASA Astrophysics Data System (ADS)

Mueller, David S.

2013-04-01

Selection of the appropriate extrapolation methods for computing the discharge in the unmeasured top and bottom parts of a moving-boat acoustic Doppler current profiler (ADCP) streamflow measurement is critical to the total discharge computation. The software tool, extrap, combines normalized velocity profiles from the entire cross section and multiple transects to determine a mean profile for the measurement. The use of an exponent derived from normalized data from the entire cross section is shown to be valid for application of the power velocity distribution law in the computation of the unmeasured discharge in a cross section. Selected statistics are combined with empirically derived criteria to automatically select the appropriate extrapolation methods. A graphical user interface (GUI) provides the user tools to visually evaluate the automatically selected extrapolation methods and manually change them, as necessary. The sensitivity of the total discharge to available extrapolation methods is presented in the GUI. Use of extrap by field hydrographers has demonstrated that extrap is a more accurate and efficient method of determining the appropriate extrapolation methods compared with tools currently (2012) provided in the ADCP manufacturers' software.

Electron impact excitation of the n = 2 to n = 3 transition in atomic hydrogen near threshold

NASA Astrophysics Data System (ADS)

Hata, J.; Morgan, L. A.; McDowell, M. R. C.

1980-06-01

Close-coupling calculations of electron impact excitation of the n = 2 to n = 3 transition of atomic hydrogen at energies below the n = 4 threshold are presented. The algebraic variational close-coupling code of Morgan (1980) with an eighteen-state basis was used to obtain cross sections at eight impact energies from 2.04 to 2.45 eV, and calculations in a six-state close-coupling model were compared with the six-state calculations of Burke et al. (1967). The six-state values are found to be in satisfactory agreement with the exception of the singlet contribution to the 2s-3s transition. Near the n = 3 threshold the cross section obtained in the full calculation is found to be almost a factor of 2 lower than that predicted by Johnson (1972), thus explaining in part the discrepancy between Johnson's results and experiments on hydrogen plasmas. Estimates of rate coefficients based on the cross sections and assuming a Maxwellian velocity distribution, however, are shown to remain in disagreement with experiment.

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

Guttormsen, M.; Goriely, S.; Larsen, A. C.

Here, nuclear level densities (NLDs) and γ-ray strength functions (γSFs) have been extracted from particle-γ coincidences of the 92Zr(p,p´γ) 92Zr and 92Zr (p,dγ) 91Zr reactions using the Oslo method. The new 91,92Zr γSF data, combined with photonuclear cross sections, cover the whole energy range from Eγ ≈ 1.5 MeV up to the giant dipole resonance at Eγ ≈ 17 MeV. The wide-range γSF data display structures at Eγ ≈ 9.5 MeV, compatible with a superposition of the spin-flip M1 resonance and a pygmy E1 resonance. Furthermore, the γSF shows a minimum at Eγ ≈ 2–3 MeV and an increase atmore » lower γ-ray energies. The experimentally constrained NLDs and γSFs are shown to reproduce known (n,γ) and Maxwellian-averaged cross sections for 91,92Zr using the TALYS reaction code, thus serving as a benchmark for this indirect method of estimating (n,γ) cross sections for Zr isotopes.« less

Towards a Resolution of the Proton Form Factor Problem: New Electron and Positron Scattering Data

NASA Astrophysics Data System (ADS)

Adikaram, D.; Rimal, D.; Weinstein, L. B.; Raue, B.; Khetarpal, P.; Bennett, R. P.; Arrington, J.; Brooks, W. K.; Adhikari, K. P.; Afanasev, A. V.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Battaglieri, M.; Bedlinskiy, I.; Biselli, A. S.; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Burkert, V. D.; Carman, D. S.; Careccia, S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dodge, G. E.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J. A.; Fradi, A.; Garillon, B.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hicks, K.; Holtrop, M.; Hughes, S. M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Jiang, H.; Jo, H. S.; Joo, K.; Joosten, S.; Kalantarians, N.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Markov, N.; Mattione, P.; Mayer, M.; McKinnon, B.; Mestayer, M. D.; Meyer, C. A.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moody, C. I.; Moutarde, H.; Movsisyan, A.; Camacho, C. Munoz; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Pasyuk, E.; Peña, C.; Pisano, S.; Pogorelko, O.; Price, J. W.; Procureur, S.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Sharabian, Y. G.; Simonyan, A.; Skorodumina, I.; Smith, E. S.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tian, Ye; Trivedi, A.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.; CLAS Collaboration

2015-02-01

There is a significant discrepancy between the values of the proton electric form factor, GEp, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GEp from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (ɛ ) and momentum transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ɛ at Q2=1.45 GeV2 . This measurement is consistent with the size of the form factor discrepancy at Q2≈1.75 GeV2 and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2 - 3 GeV2 .

A two-parameter scintillation spectrometer system for measurement of secondary proton, deuteron, and triton distributions from materials under 558-MeV-proton irradiation

NASA Technical Reports Server (NTRS)

Beck, S. M.

1975-01-01

A two-parameter scintillation spectrometer system developed and used to obtain proton, deuteron, and triton double differential cross sections from materials under 558-MeV-proton irradiation is described. The system measures both the time of flight of secondary particles over a 488-cm flight path and the energy deposited in a scintillator, 12.7 cm in diameter and 30.48 cm long. The time resolution of the system is 0.39 nsec. The calculated energy resolution based on this time resolution varies with energy from 1.6 precent to 7.75 percent for 50- and 558-MeV protons. Various systematic and statistical errors are evaluated, and the double differential cross sections for secondary proton and deutron production at 20 deg from a 2.35 g/sq cm thick beryllium target are shown as an example of the results obtainable with this system. The uncertainly in the cross sections for secondary protons varies with particle energy from approximately + or - 9 percent at 50 MeV to approximately + or - 11 percent at 558 MeV.

Rank-based testing of equal survivorship based on cross-sectional survival data with or without prospective follow-up.

PubMed

Chan, Kwun Chuen Gary; Qin, Jing

2015-10-01

Existing linear rank statistics cannot be applied to cross-sectional survival data without follow-up since all subjects are essentially censored. However, partial survival information are available from backward recurrence times and are frequently collected from health surveys without prospective follow-up. Under length-biased sampling, a class of linear rank statistics is proposed based only on backward recurrence times without any prospective follow-up. When follow-up data are available, the proposed rank statistic and a conventional rank statistic that utilizes follow-up information from the same sample are shown to be asymptotically independent. We discuss four ways to combine these two statistics when follow-up is present. Simulations show that all combined statistics have substantially improved power compared with conventional rank statistics, and a Mantel-Haenszel test performed the best among the proposal statistics. The method is applied to a cross-sectional health survey without follow-up and a study of Alzheimer's disease with prospective follow-up. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Production of W + W - pairs via γ * γ * → W + W - subprocess with photon transverse momenta

NASA Astrophysics Data System (ADS)

Łuszczak, Marta; Schäfer, Wolfgang; Szczurek, Antoni

2018-05-01

We discuss production of W + W - pairs in proton-proton collisions induced by two-photon fusion including, for a first time, transverse momenta of incoming photons. The unintegrated inelastic fluxes (related to proton dissociation) of photons are calculated based on modern parametrizations of deep inelastic structure functions in a broad range of their arguments ( x and Q 2). In our approach we can get separate contributions of different W helicities states. Several one- and two-dimensional differential distributions are shown and discussed. The present results are compared to the results of previous calculations within collinear factorization approach. Similar results are found except of some observables such as e.g. transverse momentum of the pair of W + and W -. We find large contributions to the cross section from the region of large photon virtualities. We show decomposition of the total cross section as well as invariant mass distribution into the polarisation states of both W bosons. The role of the longitudinal F L structure function is quantified. Its inclusion leads to a 4-5% decrease of the cross section, almost independent of M WW .

Maximum likelihood orientation estimation of 1-D patterns in Laguerre-Gauss subspaces.

PubMed

Di Claudio, Elio D; Jacovitti, Giovanni; Laurenti, Alberto

2010-05-01

A method for measuring the orientation of linear (1-D) patterns, based on a local expansion with Laguerre-Gauss circular harmonic (LG-CH) functions, is presented. It lies on the property that the polar separable LG-CH functions span the same space as the 2-D Cartesian separable Hermite-Gauss (2-D HG) functions. Exploiting the simple steerability of the LG-CH functions and the peculiar block-linear relationship among the two expansion coefficients sets, maximum likelihood (ML) estimates of orientation and cross section parameters of 1-D patterns are obtained projecting them in a proper subspace of the 2-D HG family. It is shown in this paper that the conditional ML solution, derived by elimination of the cross section parameters, surprisingly yields the same asymptotic accuracy as the ML solution for known cross section parameters. The accuracy of the conditional ML estimator is compared to the one of state of art solutions on a theoretical basis and via simulation trials. A thorough proof of the key relationship between the LG-CH and the 2-D HG expansions is also provided.

Experimental study on beryllium-7 production via sequential reactions in lithium-containing compounds irradiated by 14 MeV neutrons

NASA Astrophysics Data System (ADS)

Maekawa, F.; Verzilov, Y. M.; Smith, D. L.; Ikeda, Y.

2000-12-01

Except for 3H and 14C, no radioactive nuclide is produced by neutron-induced reactions with lithium in lithium-containing materials such as Li 2O and Li 2CO 3. However, when the lithium-containing materials are irradiated by 14 MeV neutrons, radioactive 7Be is produced by sequential charged particle reactions (SCPR). In this study, we measured effective 7Be production cross-sections in several lithium-containing samples at 14 MeV: the cross-sections are in the order of μb. Estimation of the effective cross-sections is attempted, and the estimated values agreed well with the experimental data. It was shown that the 7Be activity in a unit volume of lithium-containing materials in D-T fusion reactors can exceed total activity of the same unit volume of the SiC structural material in a certain cooling time. Consequently, a careful consideration of the 7Be production by SCPR is required to assess radioactive inventories in lithium-containing D-T fusion blanket materials.

A Longitudinal Study of Financial Difficulties and Mental Health in a National Sample of British Undergraduate Students.

PubMed

Richardson, Thomas; Elliott, Peter; Roberts, Ron; Jansen, Megan

2017-04-01

Previous research has shown a relationship between financial difficulties and poor mental health in students, but most research is cross-sectional. To examine longitudinal relationships over time between financial variables and mental health in students. A national sample of 454 first year British undergraduate students completed measures of mental health and financial variables at up to four time points across a year. Cross-sectional relationships were found between poorer mental health and female gender, having a disability and non-white ethnicity. Greater financial difficulties predicted greater depression and stress cross-sectionally, and also predicted poorer anxiety, global mental health and alcohol dependence over time. Depression worsened over time for those who had considered abandoning studies or not coming to university for financial reasons, and there were effects for how students viewed their student loan. Anxiety and alcohol dependence also predicted worsening financial situation suggesting a bi-directional relationship. Financial difficulties appear to lead to poor mental health in students with the possibility of a vicious cycle occurring.

Stiffness Characteristics of Composite Rotor Blades With Elastic Couplings

NASA Technical Reports Server (NTRS)

Piatak, David J.; Nixon, Mark W.; Kosmatka, John B.

1997-01-01

Recent studies on rotor aeroelastic response and stability have shown the beneficial effects of incorporating elastic couplings in composite rotor blades. However, none of these studies have clearly identified elastic coupling limits and the effects of elastic couplings on classical beam stiffnesses of representative rotor blades. Knowledge of these limits and effects would greatly enhance future aeroelastic studies involving composite rotor blades. The present study addresses these voids and provides a preliminary design database for investigators who may wish to study the effects of elastic couplings on representative blade designs. The results of the present study should provide a basis for estimating the potential benefits associated with incorporating elastic couplings without the need for first designing a blade cross section and then performing a cross-section analysis to obtain the required beam section properties as is customary in the usual one-dimensional beam-type approach.

Fusion reaction cross-sections using the Wong model within Skyrme energy density based semiclassical extended Thomas Fermi approach

NASA Astrophysics Data System (ADS)

Kumar, Raj; Sharma, Manoj K.; Gupta, Raj K.

2011-11-01

First, the nuclear proximity potential, obtained by using the semiclassical extended Thomas Fermi (ETF) approach in Skyrme energy density formalism (SEDF), is shown to give more realistic barriers in frozen density approximation, as compared to the sudden approximation. Then, taking advantage of the fact that, in ETF method, different Skyrme forces give different barriers (height, position and curvature), we use the ℓ-summed extended-Wong model of Gupta and collaborators (2009) [1] under frozen densities approximation for calculating the cross-sections, where the Skyrme force is chosen with proper barrier characteristics, not-requiring additional "barrier modification" effects (lowering or narrowing, etc.), for a best fit to data at sub-barrier energies. The method is applied to capture cross-section data from 48Ca + 238U, 244Pu, and 248Cm reactions and to fusion-evaporation cross-sections from 58Ni + 58Ni, 64Ni + 64Ni, and 64Ni + 100Mo reactions, with effects of deformations and orientations of nuclei included, wherever required. Interestingly, whereas the capture cross-sections in Ca-induced reactions could be fitted to any force, such as SIII, SV and GSkI, by allowing a small change of couple of units in deduced ℓ-values at below-barrier energies, the near-barrier data point of 48Ca + 248Cm reaction could not be fitted to ℓ-values deduced for below-barrier energies, calling for a check of data. On the other hand, the fusion-evaporation cross-sections in Ni-induced reactions at sub-barrier energies required different Skyrme forces, representing "modifications of the barrier", for the best fit to data at all incident center-of-mass energies E's, displaying a kind of fusion hindrance at sub-barrier energies. This barrier modification effect is taken into care here by using different Skyrme forces for reactions belonging to different regions of the periodic table. Note that more than one Skyrme force (with identical barrier characteristics) could equally well fit the same data.

Validity of linear encoder measurement of sit-to-stand performance power in older people.

PubMed

Lindemann, U; Farahmand, P; Klenk, J; Blatzonis, K; Becker, C

2015-09-01

To investigate construct validity of linear encoder measurement of sit-to-stand performance power in older people by showing associations with relevant functional performance and physiological parameters. Cross-sectional study. Movement laboratory of a geriatric rehabilitation clinic. Eighty-eight community-dwelling, cognitively unimpaired older women (mean age 78 years). Sit-to-stand performance power and leg power were assessed using a linear encoder and the Nottingham Power Rig, respectively. Gait speed was measured on an instrumented walkway. Maximum quadriceps and hand grip strength were assessed using dynamometers. Mid-thigh muscle cross-sectional area of both legs was measured using magnetic resonance imaging. Associations of sit-to-stand performance power with power assessed by the Nottingham Power Rig, maximum gait speed and muscle cross-sectional area were r=0.646, r=0.536 and r=0.514, respectively. A linear regression model explained 50% of the variance in sit-to-stand performance power including muscle cross-sectional area (p=0.001), maximum gait speed (p=0.002), and power assessed by the Nottingham Power Rig (p=0.006). Construct validity of linear encoder measurement of sit-to-stand power was shown at functional level and morphological level for older women. This measure could be used in routine clinical practice as well as in large-scale studies. DRKS00003622. Copyright © 2015 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

Excitation Spectra and Brightness Optimization of Two-Photon Excited Probes

PubMed Central

Mütze, Jörg; Iyer, Vijay; Macklin, John J.; Colonell, Jennifer; Karsh, Bill; Petrášek, Zdeněk; Schwille, Petra; Looger, Loren L.; Lavis, Luke D.; Harris, Timothy D.

2012-01-01

Two-photon probe excitation data are commonly presented as absorption cross section or molecular brightness (the detected fluorescence rate per molecule). We report two-photon molecular brightness spectra for a diverse set of organic and genetically encoded probes with an automated spectroscopic system based on fluorescence correlation spectroscopy. The two-photon action cross section can be extracted from molecular brightness measurements at low excitation intensities, while peak molecular brightness (the maximum molecular brightness with increasing excitation intensity) is measured at higher intensities at which probe photophysical effects become significant. The spectral shape of these two parameters was similar across all dye families tested. Peak molecular brightness spectra, which can be obtained rapidly and with reduced experimental complexity, can thus serve as a first-order approximation to cross-section spectra in determining optimal wavelengths for two-photon excitation, while providing additional information pertaining to probe photostability. The data shown should assist in probe choice and experimental design for multiphoton microscopy studies. Further, we show that, by the addition of a passive pulse splitter, nonlinear bleaching can be reduced—resulting in an enhancement of the fluorescence signal in fluorescence correlation spectroscopy by a factor of two. This increase in fluorescence signal, together with the observed resemblance of action cross section and peak brightness spectra, suggests higher-order photobleaching pathways for two-photon excitation. PMID:22385865

An integral equation method for the homogenization of unidirectional fibre-reinforced media; antiplane elasticity and other potential problems.

PubMed

Joyce, Duncan; Parnell, William J; Assier, Raphaël C; Abrahams, I David

2017-05-01

In Parnell & Abrahams (2008 Proc. R. Soc. A 464 , 1461-1482. (doi:10.1098/rspa.2007.0254)), a homogenization scheme was developed that gave rise to explicit forms for the effective antiplane shear moduli of a periodic unidirectional fibre-reinforced medium where fibres have non-circular cross section. The explicit expressions are rational functions in the volume fraction. In that scheme, a (non-dilute) approximation was invoked to determine leading-order expressions. Agreement with existing methods was shown to be good except at very high volume fractions. Here, the theory is extended in order to determine higher-order terms in the expansion. Explicit expressions for effective properties can be derived for fibres with non-circular cross section, without recourse to numerical methods. Terms appearing in the expressions are identified as being associated with the lattice geometry of the periodic fibre distribution, fibre cross-sectional shape and host/fibre material properties. Results are derived in the context of antiplane elasticity but the analogy with the potential problem illustrates the broad applicability of the method to, e.g. thermal, electrostatic and magnetostatic problems. The efficacy of the scheme is illustrated by comparison with the well-established method of asymptotic homogenization where for fibres of general cross section, the associated cell problem must be solved by some computational scheme.

HIGH PRECISION K-SHELL PHOTOABSORPTION CROSS SECTIONS FOR ATOMIC OXYGEN: EXPERIMENT AND THEORY

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

McLaughlin, B. M.; Ballance, C. P.; Bowen, K. P.

2013-07-01

Photoabsorption of atomic oxygen in the energy region below the 1s {sup -1} threshold in X-ray spectroscopy from Chandra and XMM-Newton is observed in a variety of X-ray binary spectra. Photoabsorption cross sections determined from an R-matrix method with pseudo-states and new, high precision measurements from the Advanced Light Source (ALS) are presented. High-resolution spectroscopy with E/{Delta}E Almost-Equal-To 4250 {+-} 400 was obtained for photon energies from 520 eV to 555 eV at an energy resolution of 124 {+-} 12 meV FWHM. K-shell photoabsorption cross section measurements were made with a re-analysis of previous experimental data on atomic oxygen atmore » the ALS. Natural line widths {Gamma} are extracted for the 1s {sup -1}2s {sup 2}2p {sup 4}({sup 4} P)np {sup 3} P Degree-Sign and 1s {sup -1}2s {sup 2}2p {sup 4}({sup 2} P)np {sup 3} P Degree-Sign Rydberg resonances series and compared with theoretical predictions. Accurate cross sections and line widths are obtained for applications in X-ray astronomy. Excellent agreement between theory and the ALS measurements is shown which will have profound implications for the modeling of X-ray spectra and spectral diagnostics.« less

Electron-Impact Cross Sections for Ground State to np Excitations of Sodium and Potassium.

PubMed

Stone, Philip M; Kim, Yong-Ki

2004-01-01

Cross sections for electron impact excitation of atoms are important for modeling of low temperature plasmas and gases. While there are many experimental and theoretical results for excitation to the first excited states, little information is available for excitation to higher states. We present here calculations of excitations from the ground state to the np levels of sodium (n = 3 through 11) and potassium (n = 4 through 12). We also present a calculation for a transition from the excited sodium level 3p to 3d to show the generality of the method. Scaling formulas developed earlier by Kim [Phys. Rev. A 64, 032713 (2001)] for plane-wave Born cross sections are used. These formulas have been shown to be remarkably accurate yet simple to use. We have used a core polarization potential in a Dirac-Fock wave function code to calculate target atom wave functions and a matching form of the dipole transition operator to calculate oscillator strengths and Born cross sections. The scaled Born results here for excitation to the first excited levels are in very good agreement with experimental and other theoretical data, and the results for excitation to the next few levels are in satisfactory agreement with the limited data available. The present results for excitation to the higher levels are believed to be the only data available.

An integral equation method for the homogenization of unidirectional fibre-reinforced media; antiplane elasticity and other potential problems

PubMed Central

Joyce, Duncan

2017-01-01

In Parnell & Abrahams (2008 Proc. R. Soc. A 464, 1461–1482. (doi:10.1098/rspa.2007.0254)), a homogenization scheme was developed that gave rise to explicit forms for the effective antiplane shear moduli of a periodic unidirectional fibre-reinforced medium where fibres have non-circular cross section. The explicit expressions are rational functions in the volume fraction. In that scheme, a (non-dilute) approximation was invoked to determine leading-order expressions. Agreement with existing methods was shown to be good except at very high volume fractions. Here, the theory is extended in order to determine higher-order terms in the expansion. Explicit expressions for effective properties can be derived for fibres with non-circular cross section, without recourse to numerical methods. Terms appearing in the expressions are identified as being associated with the lattice geometry of the periodic fibre distribution, fibre cross-sectional shape and host/fibre material properties. Results are derived in the context of antiplane elasticity but the analogy with the potential problem illustrates the broad applicability of the method to, e.g. thermal, electrostatic and magnetostatic problems. The efficacy of the scheme is illustrated by comparison with the well-established method of asymptotic homogenization where for fibres of general cross section, the associated cell problem must be solved by some computational scheme. PMID:28588412

Influence of Triply-Charged Ions and Ionization Cross-Sections in a Hybrid-PIC Model of a Hall Thruster Discharge

NASA Technical Reports Server (NTRS)

Smith, Brandon D.; Boyd, Iain D.; Kamhawi, Hani

2014-01-01

The sensitivity of xenon ionization rates to collision cross-sections is studied within the framework of a hybrid-PIC model of a Hall thruster discharge. A revised curve fit based on the Drawin form is proposed and is shown to better reproduce the measured crosssections at high electron energies, with differences in the integrated rate coefficients being on the order of 10% for electron temperatures between 20 eV and 30 eV. The revised fit is implemented into HPHall and the updated model is used to simulate NASA's HiVHAc EDU2 Hall thruster at discharge voltages of 300, 400, and 500 V. For all three operating points, the revised cross-sections result in an increase in the predicted thrust and anode efficiency, reducing the error relative to experimental performance measurements. Electron temperature and ionization reaction rates are shown to follow the trends expected based on the integrated rate coefficients. The effects of triply-charged xenon are also assessed. The predicted thruster performance is found to have little or no dependence on the presence of triply-charged ions. The fraction of ion current carried by triply-charged ions is found to be on the order of 1% and increases slightly with increasing discharge voltage. The reaction rates for the 0?III, I?III, and II?III ionization reactions are found to be of similar order of magnitude and are about one order of magnitude smaller than the rate of 0?II ionization in the discharge channel.

Twist-3 contributions to wide-angle photoproduction of pions

NASA Astrophysics Data System (ADS)

Kroll, P.; Passek-Kumerički, K.

2018-04-01

We investigate wide-angle π0 photoproduction within the handbag approach to twist-3 accuracy. In contrast to earlier work both the 2-particle as well as the 3-particle twist-3 contributions are taken into account. It is shown that both are needed for consistent results that respect gauge invariance and crossing properties. The numerical studies reveal the dominance of the twist-3 contribution. With it fair agreement with the recent CLAS measurement of the π0 cross section is obtained. We briefly comment also on wide-angle photoproduction of other pseudoscalar mesons.

Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability

DOE PAGES

Appelquist, T.; Berkowitz, E.; Brower, R. C.; ...

2015-10-23

We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar “stealth baryon” dark matter candidate, arising from a dark SU(4) confining gauge theory—“stealth dark matter.” In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest “baryon” states in SU(3) and SU(4) gauge theories using themore » background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N) groups. The resulting scattering cross sections with a xenon target are shown to be possibly detectable in the dark matter mass range of about 200–700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1/m 6 B, suggests the observable dark matter mass range is not appreciably modified. We highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter.« less

Development of a general method for obtaining the geometry of microfluidic networks

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

Razavi, Mohammad Sayed, E-mail: m.sayedrazavi@gmail.com; Salimpour, M. R.; Shirani, Ebrahim

2014-01-15

In the present study, a general method for geometry of fluidic networks is developed with emphasis on pressure-driven flows in the microfluidic applications. The design method is based on general features of network's geometry such as cross-sectional area and length of channels. Also, the method is applicable to various cross-sectional shapes such as circular, rectangular, triangular, and trapezoidal cross sections. Using constructal theory, the flow resistance, energy loss and performance of the network are optimized. Also, by this method, practical design strategies for the fabrication of microfluidic networks can be improved. The design method enables rapid prediction of fluid flowmore » in the complex network of channels and is very useful for improving proper miniaturization and integration of microfluidic networks. Minimization of flow resistance of the network of channels leads to universal constants for consecutive cross-sectional areas and lengths. For a Y-shaped network, the optimal ratios of consecutive cross-section areas (A{sub i+1}/A{sub i}) and lengths (L{sub i+1}/L{sub i}) are obtained as A{sub i+1}/A{sub i} = 2{sup −2/3} and L{sub i+1}/L{sub i} = 2{sup −1/3}, respectively. It is shown that energy loss in the network is proportional to the volume of network. It is also seen when the number of channels is increased both the hydraulic resistance and the volume occupied by the network are increased in a similar manner. Furthermore, the method offers that fabrication of multi-depth and multi-width microchannels should be considered as an integral part of designing procedures. Finally, numerical simulations for the fluid flow in the network have been performed and results show very good agreement with analytic results.« less

Transmission electron microscope studies of extraterrestrial materials

NASA Technical Reports Server (NTRS)

Keller, Lindsay P.

1995-01-01

Transmission Electron Microscopy, X-Ray spectrometry and electron-energy-loss spectroscopy are used to analyse carbon in interplanetary dust particles. Optical micrographs are shown depicting cross sections of the dust particles embedded in sulphur. Selected-area electron diffraction patterns are shown. Transmission Electron Microscope specimens of lunar soil were prepared using two methods: ion-milling and ultramicrotomy. A combination of high resolution TEM imaging and electron diffraction is used to characterize the opaque assemblages. The opaque assemblages analyzed in this study are dominated by ilmenite with lesser rutile and spinel exsolutions, and traces of Fe metal.

Organic Photonics: Toward a New Generation of Thin Film Photovoltaics and Lasers

DTIC Science & Technology

2011-03-07

plane. 39 Both electron and x - ray diffraction confirm the existence of crystalline domains of CuPc and C60. Crystalline domain sizes range from 5...nanocrystalline domains indicated by white curves that locate the domain boundaries. Scale bar=5 nm. b, X - ray diffraction pattern of an OVPD grown A... ray diffraction (XRD) and atomic force microscopy (AFM), as shown in Fig. 8. A cross-sectional TEM image of [CuPc(6.1nm)/C60(6.1nm)]10 is shown in

Oppositional Behavior and Anxiety in Boys and Girls: A Cross-Sectional Study in Two Community Samples

ERIC Educational Resources Information Center

Mireault, Gina; Rooney, Siri; Kouwenhoven, Kristen; Hannan, Carolyn

2008-01-01

Studies have repeatedly shown that oppositional behavior is linked to anxiety in clinical samples of children. This study explored whether these variables were similarly related in nonclinical samples of elementary and middle school students (N = 302). Despite greater self-reported oppositional behavior among boys in these samples, anxiety…

Charged black lens in de Sitter space

NASA Astrophysics Data System (ADS)

Tomizawa, Shinya

2018-02-01

We obtain a charged black lens solution in the five-dimensional Einstein-Maxwell-Chern-Simons theory with a positive cosmological constant. It is shown that the solution obtained here describes the formation of a black hole with the spatial cross section of a sphere from that of the lens space of L (n ,1 ) in five-dimensional de Sitter space.

Correction to: A national cohort study on pediatric Behçet's disease: cross-sectional data from an Italian registry.

PubMed

Gallizzi, Romina; Pidone, Caterina; Cantarini, Luca; Finetti, Martina; Cattalini, Marco; Filocamo, Giovanni; Insalaco, Antonella; Rigante, Donato; Consolini, Rita; Maggio, Maria Cristina; Civino, Adele; Martino, Silvana; Olivieri, Alma Nunzia; Fabio, Giovanna; Pastore, Serena; Mauro, Angela; Sutera, Diana; Trimarchi, Giuseppe; Ruperto, Nicolino; Gattorno, Marco; Cimaz, Rolando

2018-04-23

Following publication of the original article [1], the authors reported that the names of two institutional authors - EUROFEVER and the Paediatric Rheumatology International Trials Organisation (PRINTO) - had been unintentionally omitted in the final online version of the manuscript. The corrected author list is shown in this Correction..

The Nature and Extent of Help Given to Women with Intellectual Disabilities to Manage Menstruation

ERIC Educational Resources Information Center

Rodgers, Jackie; Lipscombe, Jo

2005-01-01

Menstruation has been shown to be problematic for many women with intellectual disabilities. There has been a greater focus on menstrual suppression or elimination than on help and training to manage menstrual care successfully. A cross-sectional questionnaire survey was conducted in England to investigate the help and training currently given to…

A first principles study of commonly observed planar defects in Ti/TiB system

DOE PAGES

Nandwana, Peeyush; Gupta, Niraj; Srinivasan, Srivilliputhur G.; ...

2018-04-20

Here, TiB exhibits a hexagonal cross-section with growth faults on (1 0 0) planes and contains B27-B f bicrystals. The hexagonal cross-section is presently explained by surface free energy minimization principle. We show that interfacial energy calculations explain the longer (1 0 0) facet compared to (1 0 1) type facets whereas free surface energy arguments do not provide the true picture. No quantitative explanation of stacking faults and B27-B f interfaces in TiB exists. We show that the low formation energy of stacking faults and B27-B f interfaces explain their abundance. The low energy barrier for B f formationmore » is shown to be responsible for their presence in TiB.« less

Hybrid theory and calculation of e-N2 scattering. [quantum mechanics - nuclei (nuclear physics)

NASA Technical Reports Server (NTRS)

Chandra, N.; Temkin, A.

1975-01-01

A theory of electron-molecule scattering was developed which was a synthesis of close coupling and adiabatic-nuclei theories. The theory is shown to be a close coupling theory with respect to vibrational degrees of freedom but is a adiabatic-nuclei theory with respect to rotation. It can be applied to any number of partial waves required, and the remaining ones can be calculated purely in one or the other approximation. A theoretical criterion based on fixed-nuclei calculations and not on experiment can be given as to which partial waves and energy domains require the various approximations. The theory allows all cross sections (i.e., pure rotational, vibrational, simultaneous vibration-rotation, differential and total) to be calculated. Explicit formulae for all the cross sections are presented.

Dissociative recombination of O2(+), NO(+) and N2(+)

NASA Technical Reports Server (NTRS)

Guberman, S. L.

1983-01-01

A new L(2) approach for the calculation of the threshold molecular capture width needed for the determination of DR cross sections was developed. The widths are calculated with Fermi's golden rule by substituting Rydberg orbitals for the free electron continuum coulomb orbital. It is shown that the calculated width converges exponentially as the effective principal quantum number of the Rydberg orbital increases. The threshold capture width is then easily obtained. Since atmospheric recombination involves very low energy electrons, the threshold capture widths are essential to the calculation of DR cross sections for the atmospheric species studied here. The approach described makes use of bound state computer codes already in use. A program that collects width matrix elements over CI wavefunctions for the initial and final states is described.

Measurement of the cross section and longitudinal double-spin asymmetry for dijet production in polarized p p collisions at s = 200 GeV

DOE PAGES

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; ...

2017-04-28

We report the first measurement of the longitudinal double-spin asymmetry A LL for mid-rapidity dijet production in polarized pp collisions at a center-of-mass energy ofmore » $$\\sqrt{s}$$ = 200 GeV. The dijet cross section was measured and is shown to be consistent with next-to-leading order (NLO) perturbative QCD predictions. A LL results are presented for two distinct topologies, defined by the jet pseudorapidities, and are compared to predictions from several recent NLO global analyses. Lastly, the measured asymmetries, the first such correlation measurements, support those analyses that find positive gluon polarization at the level of roughly 0.2 over the region of Bjorken-x > 0.05.« less

Indium hexagonal island as seed-layer to boost a-axis orientation of AlN thin films

NASA Astrophysics Data System (ADS)

Redjdal, N.; Salah, H.; Azzaz, M.; Menari, H.; Manseri, A.; Guedouar, B.; Garcia-Sanchez, A.; Chérif, S. M.

2018-06-01

Highly a-axis oriented aluminum nitride films have been grown on Indium coated (100) Si substrate by DC reactive magnetron sputtering. It is shown that In incorporated layer improve the extent of preferential growth along (100) axis and form dense AlN films with uniform surface and large grains, devoid of micro-cracks. As revealed by SEM cross section images, AlN structure consists of oriented columnar grains perpendicular to the Si surface, while AlN/In structure results in uniformely tilted column. SEM images also revealed the presence of In hexagonal islands persistent throughout the entire growth. Micro -Raman spectroscopy of the surface and the cross section of the AlN/In grown films evidenced their high degree of homogeneity and cristallinity.

Coupled-Sturmian and perturbative treatments of electron transfer and ionization in high-energy p-He+ collisions

NASA Astrophysics Data System (ADS)

Winter, Thomas G.; Alston, Steven G.

1992-02-01

Cross sections have been determined for electron transfer and ionization in collisions between protons and He+ ions at proton energies from several hundred kilo-electron-volts to 2 MeV. A coupled-Sturmian approach is taken, extending the work of Winter [Phys. Rev. A 35, 3799 (1987)] and Stodden et al. [Phys. Rev. A 41, 1281 (1990)] to high energies where perturbative approaches are expected to be valid. An explicit connection is made with the first-order Born approximation for ionization and the impulse version of the distorted, strong-potential Born approximation for electron transfer. The capture cross section is shown to be affected by the presence of target basis functions of positive energy near v2/2, corresponding to the Thomas mechanism.

Multistatic GNSS Receiver Array for Passive Air Surveillance

NASA Astrophysics Data System (ADS)

Wachtl, Stefan; Koch, Volker; Westphal, Robert; Schmidt, Lorenz-Peter

2016-03-01

The performance of a passive air surveillance sensor based on Global Navigation Satellite Systems (GNSS) is mainly limited by the receiver noise efficiency, the achievable signal processing gain and the radar cross section (RCS) of an airplane. For surveillance applications large detection ranges as well as a high probability of detection are crucial parameters. Due to the very low GNSS signal powers received on the earth's surface, high radar cross sections are mandatory to achieve detection ranges for airplanes at some kilometers distance. This paper will discuss a multistatic transmitter and receiver arrangement, which is indispensable to get a reasonable detection rate with respect to a hemispheric field of view. The strong performance dependency of such a sensor on the number of transmitters and receivers will be shown by means of some exemplary simulation results.

Evidence of halo structure in 37Mg observed via reaction cross sections and intruder orbitals beyond the island of inversion

NASA Astrophysics Data System (ADS)

Takechi, M.; Suzuki, S.; Nishimura, D.; Fukuda, M.; Ohtsubo, T.; Nagashima, M.; Suzuki, T.; Yamaguchi, T.; Ozawa, A.; Moriguchi, T.; Ohishi, H.; Sumikama, T.; Geissel, H.; Aoi, N.; Chen, Rui-Jiu; Fang, De-Qing; Fukuda, N.; Fukuoka, S.; Furuki, H.; Inabe, N.; Ishibashi, Y.; Itoh, T.; Izumikawa, T.; Kameda, D.; Kubo, T.; Lantz, M.; Lee, C. S.; Ma, Yu-Gang; Matsuta, K.; Mihara, M.; Momota, S.; Nagae, D.; Nishikiori, R.; Niwa, T.; Ohnishi, T.; Okumura, K.; Ohtake, M.; Ogura, T.; Sakurai, H.; Sato, K.; Shimbara, Y.; Suzuki, H.; Takeda, H.; Takeuchi, S.; Tanaka, K.; Tanaka, M.; Uenishi, H.; Winkler, M.; Yanagisawa, Y.; Watanabe, S.; Minomo, K.; Tagami, S.; Shimada, M.; Kimura, M.; Matsumoto, T.; Shimizu, Y. R.; Yahiro, M.

2014-12-01

Precise reaction cross sections (σR) for Mg-3824 on C targets at energies around 240 MeV/nucleon have been measured at the Radioactive Isotope Beam Factory at RIKEN. The σR for Mg-3836 have been measured for the first time. An enhancement of σR compared to the systematics for spherical stable nuclei has been observed, especially in the neutron-rich region, which reflects the deformation of those isotopes. In the vicinity of the drip line the σR for 37Mg is especially large. It is shown by analysis using a recently developed theoretical method that this prominent enhancement of σR for 37Mg should come from the p -orbital halo formation breaking the N =28 shell gap.

A first principles study of commonly observed planar defects in Ti/TiB system

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

Nandwana, Peeyush; Gupta, Niraj; Srinivasan, Srivilliputhur G.

Here, TiB exhibits a hexagonal cross-section with growth faults on (1 0 0) planes and contains B27-B f bicrystals. The hexagonal cross-section is presently explained by surface free energy minimization principle. We show that interfacial energy calculations explain the longer (1 0 0) facet compared to (1 0 1) type facets whereas free surface energy arguments do not provide the true picture. No quantitative explanation of stacking faults and B27-B f interfaces in TiB exists. We show that the low formation energy of stacking faults and B27-B f interfaces explain their abundance. The low energy barrier for B f formationmore » is shown to be responsible for their presence in TiB.« less

Hermitian Hamiltonian equivalent to a given non-Hermitian one: manifestation of spectral singularity.

PubMed

Samsonov, Boris F

2013-04-28

One of the simplest non-Hermitian Hamiltonians, first proposed by Schwartz in 1960, that may possess a spectral singularity is analysed from the point of view of the non-Hermitian generalization of quantum mechanics. It is shown that the η operator, being a second-order differential operator, has supersymmetric structure. Asymptotic behaviour of the eigenfunctions of a Hermitian Hamiltonian equivalent to the given non-Hermitian one is found. As a result, the corresponding scattering matrix and cross section are given explicitly. It is demonstrated that the possible presence of a spectral singularity in the spectrum of the non-Hermitian Hamiltonian may be detected as a resonance in the scattering cross section of its Hermitian counterpart. Nevertheless, just at the singular point, the equivalent Hermitian Hamiltonian becomes undetermined.

Effects of Microstructural Variability on Thermo-Mechanical Properties of a Woven Ceramic Matrix Composite

NASA Technical Reports Server (NTRS)

Goldsmith, Marlana B.; Sankar, Bhavani V.; Haftka, Raphael T.; Goldberg, Robert K.

2013-01-01

The objectives of this paper include identifying important architectural parameters that describe the SiC/SiC five-harness satin weave composite and characterizing the statistical distributions and correlations of those parameters from photomicrographs of various cross sections. In addition, realistic artificial cross sections of a 2D representative volume element (RVE) are generated reflecting the variability found in the photomicrographs, which are used to determine the effects of architectural variability on the thermo-mechanical properties. Lastly, preliminary information is obtained on the sensitivity of thermo-mechanical properties to architectural variations. Finite element analysis is used in combination with a response surface and it is shown that the present method is effective in determining the effects of architectural variability on thermo-mechanical properties.

Preparation and characterization of 33S samples for 33S(n, α)30Si cross-section measurements at the n_TOF facility at CERN

NASA Astrophysics Data System (ADS)

Praena, J.; Ferrer, F. J.; Vollenberg, W.; Sabaté-Gilarte, M.; Fernández, B.; García-López, J.; Porras, I.; Quesada, J. M.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Barbagallo, M.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Bosnar, D.; Brugger, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Diakaki, M.; Dietz, M.; Domingo-Pardo, C.; Dressler, R.; Durán, I.; Eleftheriadis, C.; Ferrari, A.; Fraval, K.; Furman, V.; Göbel, K.; Gómez-Hornillos, M. B.; Ganesan, S.; García, A. R.; Giubrone, G.; Gonçalves, I. F.; González-Romero, E.; Goverdovski, A.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Heftrich, T.; Hernández-Prieto, A.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Karadimos, D.; Katabuchi, T.; Ketlerov, V.; Khryachkov, V.; Kivel, N.; Koehler, P.; Kokkoris, M.; Kroll, J.; Krtička, M.; Lampoudis, C.; Langer, C.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Leong, L. S.; Lerendegui-Marco, J.; Losito, R.; Mallick, A.; Manousos, A.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondelaers, W.; Paradela, C.; Pavlik, A.; Perkowski, J.; Plompen, A. J. M.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Robles, M.; Rubbia, C.; Ryan, J. A.; Sarmento, R.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Sedyshev, P.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiss, C.; Wright, T.; Žugec, P.; n TOF Collaboration

2018-05-01

Thin 33S samples for the study of the 33S(n, α)30Si cross-section at the n_TOF facility at CERN were made by thermal evaporation of 33S powder onto a dedicated substrate made of kapton covered with thin layers of copper, chromium and titanium. This method has provided for the first time bare sulfur samples a few centimeters in diameter. The samples have shown an excellent adherence with no mass loss after few years and no sublimation in vacuum at room temperature. The determination of the mass thickness of 33S has been performed by means of Rutherford backscattering spectrometry. The samples have been successfully tested under neutron irradiation.

Thermal runaway and microwave heating in thin cylindrical domains

NASA Astrophysics Data System (ADS)

Ward, Michael J.

2002-04-01

The behaviour of the solution to two nonlinear heating problems in a thin cylinder of revolution of variable cross-sectional area is analysed using asymptotic and numerical methods. The first problem is to calculate the fold point, corresponding to the onset of thermal runaway, for a steady-state nonlinear elliptic equation that arises in combustion theory. In the limit of thin cylindrical domains, it is shown that the onset of thermal runaway can be delayed when a circular cylindrical domain is perturbed into a dumbell shape. Numerical values for the fold point for different domain shapes are obtained asymptotically and numerically. The second problem that is analysed is a nonlinear parabolic equation modelling the microwave heating of a ceramic cylinder by a known electric field. The basic model in a thin circular cylindrical domain was analysed in Booty & Kriegsmann (Meth. Appl. Anal. 4 (1994) p. 403). Their analysis is extended to treat thin cylindrical domains of variable cross-section. It is shown that the steady-state and dynamic behaviours of localized regions of high temperature, called hot-spots, depend on a competition between the maxima of the electric field and the maximum deformation of the circular cylinder. For a dumbell-shaped region it is shown that two disconnected hot-spot regions can occur. Depending on the parameters in the model, these regions, ultimately, either merge as time increases or else remain as disconnected regions for all time.

Geologic map of the Haji-Gak iron deposit, Bamyan Province, Afghanistan, modified from the 1965 original map compilation of M.S. Smirnov and I.K. Kusov

USGS Publications Warehouse

Renaud, Karine M.; Tucker, Robert D.; Peters, Stephen G.; Stettner, Will R.; Masonic, Linda M.; Moran, Thomas W.

2011-01-01

This map is a modified version of Geological-structural map of Hajigak iron-ore deposit, scale 1:10,000, which was compiled by M.S. Smirnov and I.K. Kusov in 1965. (Refer to the References Cited section in the Map PDF for complete citations of the original map and a related report.) USGS scientists, in cooperation with the Afghan Geological Survey and the Task Force for Business and Stability Operations of the U.S. Department of Defense, studied the original documents and also visited the field area in November 2009. This modified map illustrates the geological structure of the Haji-Gak iron deposit and includes cross sections of the same area. The map reproduces the topology (contacts, faults, and so forth) of the original Soviet map and cross sections and includes modifications based on our examination of these documents. Elevations on the cross sections are derived from the original Soviet topography and may not match the newer topography used on the current map. We have attempted to translate the original Russian terminology and rock classification into modern English geologic usage as literally as possible without changing any genetic or process-oriented implications in the original descriptions. We also use the age designations from the original map. The unit colors on the map and cross sections differ from the colors shown on the original version. The units are colored according to the color and pattern scheme of the Commission for the Geological Map of the World (CGMW) (http://www.ccgm.org).

A New Method for Generating Probability Tables in the Unresolved Resonance Region

DOE PAGES

Holcomb, Andrew M.; Leal, Luiz C.; Rahnema, Farzad; ...

2017-04-18

One new method for constructing probability tables in the unresolved resonance region (URR) has been developed. This new methodology is an extensive modification of the single-level Breit-Wigner (SLBW) pseudo-resonance pair sequence method commonly used to generate probability tables in the URR. The new method uses a Monte Carlo process to generate many pseudo-resonance sequences by first sampling the average resonance parameter data in the URR and then converting the sampled resonance parameters to the more robust R-matrix limited (RML) format. Furthermore, for each sampled set of pseudo-resonance sequences, the temperature-dependent cross sections are reconstructed on a small grid around themore » energy of reference using the Reich-Moore formalism and the Leal-Hwang Doppler broadening methodology. We then use the effective cross sections calculated at the energies of reference to construct probability tables in the URR. The RML cross-section reconstruction algorithm has been rigorously tested for a variety of isotopes, including 16O, 19F, 35Cl, 56Fe, 63Cu, and 65Cu. The new URR method also produced normalized cross-section factor probability tables for 238U that were found to be in agreement with current standards. The modified 238U probability tables were shown to produce results in excellent agreement with several standard benchmarks, including the IEU-MET-FAST-007 (BIG TEN), IEU-MET-FAST-003, and IEU-COMP-FAST-004 benchmarks.« less

Near resonant bubble acoustic cross-section corrections, including examples from oceanography, volcanology, and biomedical ultrasound.

PubMed

Ainslie, Michael A; Leighton, Timothy G

2009-11-01

The scattering cross-section sigma(s) of a gas bubble of equilibrium radius R(0) in liquid can be written in the form sigma(s)=4piR(0) (2)[(omega(1) (2)omega(2)-1)(2)+delta(2)], where omega is the excitation frequency, omega(1) is the resonance frequency, and delta is a frequency-dependent dimensionless damping coefficient. A persistent discrepancy in the frequency dependence of the contribution to delta from radiation damping, denoted delta(rad), is identified and resolved, as follows. Wildt's [Physics of Sound in the Sea (Washington, DC, 1946), Chap. 28] pioneering derivation predicts a linear dependence of delta(rad) on frequency, a result which Medwin [Ultrasonics 15, 7-13 (1977)] reproduces using a different method. Weston [Underwater Acoustics, NATO Advanced Study Institute Series Vol. II, 55-88 (1967)], using ostensibly the same method as Wildt, predicts the opposite relationship, i.e., that delta(rad) is inversely proportional to frequency. Weston's version of the derivation of the scattering cross-section is shown here to be the correct one, thus resolving the discrepancy. Further, a correction to Weston's model is derived that amounts to a shift in the resonance frequency. A new, corrected, expression for the extinction cross-section is also derived. The magnitudes of the corrections are illustrated using examples from oceanography, volcanology, planetary acoustics, neutron spallation, and biomedical ultrasound. The corrections become significant when the bulk modulus of the gas is not negligible relative to that of the surrounding liquid.

Low-voltage cross-sectional EBIC for characterisation of GaN-based light emitting devices.

PubMed

Moldovan, Grigore; Kazemian, Payam; Edwards, Paul R; Ong, Vincent K S; Kurniawan, Oka; Humphreys, Colin J

2007-01-01

Electron beam induced current (EBIC) characterisation can provide detailed information on the influence of crystalline defects on the diffusion and recombination of minority carriers in semiconductors. New developments are required for GaN light emitting devices, which need a cross-sectional approach to provide access to their complex multi-layered structures. A sample preparation approach based on low-voltage Ar ion milling is proposed here and shown to produce a flat cross-section with very limited surface recombination, which enables low-voltage high resolution EBIC characterisation. Dark defects are observed in EBIC images and correlation with cathodoluminescence images identify them as threading dislocations. Emphasis is placed on one-dimensional quantification which is used to show that junction delineation with very good spatial resolution can be achieved, revealing significant roughening of this GaN p-n junction. Furthermore, longer minority carrier diffusion lengths along the c-axis are found at dislocation sites, in both p-GaN and the multi-quantum well (MQW) region. This is attributed to gettering of point defects at threading dislocations in p-GaN and higher escape rate from quantum wells at dislocation sites in the MQW region, respectively. These developments show considerable promise for the use of low-voltage cross-sectional EBIC in the characterisation of point and extended defects in GaN-based devices and it is suggested that this technique will be particularly useful for degradation analysis.

Monitoring corrosion of rebar embedded in mortar using guided ultrasonic waves

NASA Astrophysics Data System (ADS)

Ervin, Benjamin Lee

This thesis investigates the use of guided mechanical waves for monitoring uniform and localized corrosion in steel reinforcing bars embedded in concrete. The main forms of structural deterioration from uniform corrosion in reinforced concrete are the destruction of the bond between steel and concrete, the loss of steel cross-sectional area, and the loss of concrete cross-sectional area from cracking and spalling. Localized corrosion, or pitting, leads to severe loss of steel cross-sectional area, creating a high risk of bar tensile failure and unintended transfer of loads to the surrounding concrete. Reinforcing bars were used to guide the waves, rather than bulk concrete, allowing for longer inspection distances due to lower material absorption, scattering, and divergence. Guided mechanical waves in low frequency ranges (50-200 kHz) and higher frequency ranges (2-8 MHz) were monitored in reinforced mortar specimens undergoing accelerated uniform corrosion. The frequency ranges chosen contain wave modes with varying amounts of interaction, i.e. displacement profile, at the material interface. Lower frequency modes were shown to be sensitive to the accumulation of corrosion product and the level of bond between the surrounding mortar and rebar. This allows for the onset of corrosion and bond deterioration to be monitored. Higher frequency modes were shown to be sensitive to changes in the bar profile surface, allowing for the loss of cross-sectional area to be monitored. Guided mechanical waves in the higher frequency range were also used to monitor reinforced mortar specimens undergoing accelerated localized corrosion. The high frequency modes were sensitive to the localized attack. Also promising was the unique frequency spectrum response for both uniform and localized corrosion, allowing the two corrosion types to be differentiated from through-transmission evaluation. The isolated effects of the reinforcing ribs, simulated debonding, simulated pitting, water surrounding, and mortar surrounding were also investigated using guided mechanical waves. Results are presented and discussed within the framework of a corrosion process degradation model and service life. A thorough review and discussion of the corrosion process, modeling the propagation of corrosion, nondestructive methods for monitoring corrosion in reinforced concrete, and guided mechanical waves have also been presented.

Individual Differences in Diabetes Risk: Role of Sleep Disturbances

DTIC Science & Technology

2008-08-01

Automated Neuropsychological Assessment Metrics (ANAM) software, a commercial version of the Walter Reed Army Institute for Research battery of...ghrelin levels, decreased levels of leptin and increased hunger and appetite. We also review cross-sectional epidemiologic studies associating...Leptin is a satiety factor: high leptin levels inhibit and low leptin levels stimulate hunger and food intake. The data shown in Figure 4

Fruit and Vegetable Attitudes, Norms, and Intake in Low-Income Youth

ERIC Educational Resources Information Center

Di Noia, Jennifer; Cullen, Karen Weber

2015-01-01

Fruit and vegetable (FV) attitudes and norms have been shown to influence intake in youth; yet research with low-income youth and studies supplementing self-report with objective measures of intake are lacking. Cross-sectional survey data on self-rated FV intake, FV attitudes, and FV norms were collected in a sample of 116 youth attending a…

Oral Contraceptives and Bone Health in Female Runners

DTIC Science & Technology

2006-10-01

activity. Previous cross-sectional research has shown that women with exercise - induced menstrual irregularities have a significantly higher...6. Cumming D.C. Exercise -associated amenorrhea , low BMD, and estrogen replacement therapy. Arch Intern Med. 156:2193-2195, 1996. 34 7. De...Science in Sports & Exercise . (i) Abstract from manuscript, “Randomized trial of the effect of oral contraceptives on bone mass and stress

Cerebellar Gray Matter Density in Females with ADHD Combined Type: A Cross-Sectional Voxel-Based Morphometry Study

ERIC Educational Resources Information Center

Almeida Montes, Luis Guillermo; Ricardo-Garcell, Josefina; De la Torre, Lazaro Barajas; Prado Alcantara, Hugo; Martinez Garcia, Reyna Beatriz; Avila Acosta, David; Fernandez Bouzas, Antonio

2011-01-01

Background: MRI studies have shown a decreased cerebellum volume in individuals with ADHD. However, most of these studies were conducted with male children, many of whom were medicated with stimulants. As such, unmedicated, non-White girls are underrepresented in such MRI studies. Objective: The aim of the present study was to compare the density…

Attention-Deficit/Hyperactivity Disorder and Sluggish Cognitive Tempo throughout Childhood: Temporal Invariance and Stability from Preschool through Ninth Grade

ERIC Educational Resources Information Center

Leopold, Daniel R.; Christopher, Micaela E.; Burns, G. Leonard; Becker, Stephen P.; Olson, Richard K.; Willcutt, Erik G.

2016-01-01

Background: Although multiple cross-sectional studies have shown symptoms of sluggish cognitive tempo (SCT) and attention-deficit/hyperactivity disorder (ADHD) to be statistically distinct, studies have yet to examine the temporal stability and measurement invariance of SCT in a longitudinal sample. To date, only six studies have assessed SCT…

Physical Activity, Well-Being and Needs Satisfaction in Eight and Nine-Year-Old Children from Areas of Socio-Economic Disadvantage

ERIC Educational Resources Information Center

Breslin, Gavin; Shannon, Stephen; Fitzpatrick, Ben; Hanna, Donncha; Belton, Sarahjane; Brennan, Deirdre

2017-01-01

Need-supportive environments have been shown to predict children's physical activity levels, and in a few cases to well-being. Grounded in self-determination theory (SDT), this cross-sectional study aimed to determine the influence of psychological need (competence and social relatedness) satisfaction on physical activity levels and well-being in…

Development of a bending stiffness model for wet process fiberboard

Treesearch

Chris Turk; John F. Hunt

2007-01-01

In traditional mechanics of materials, the stiffness of a beam or plate in bending is described by its cross-sectional shape as well as its material properties, primarily the modulus of elasticity. Previous work at the USDA Forest Products Laboratory, Madison, Wisconsin, has shown that modulus of elasticity has a strong correlation to the density of the fiberboard....

Hard diffraction from quasi-elastic dipole scattering

NASA Astrophysics Data System (ADS)

Bialas, A.; Peschanski, R.

1996-02-01

The contribution to diffraction dissociation of virtual photons due to quasi-elastic scattering of the q- overlineq component is calculated in the framework of the QCD dipole picture. Both longitudinal and transverse components of the cross-section are given. It is shown that, at fixed mass of the diffractively produced system, quantum mechanical interference plays an important rôle. Phenomenological consequences are discussed.

A Method of Assembling Cross-Sectional Indicators into a Community Quality of Life

ERIC Educational Resources Information Center

Epley, Donald R.; Menon, Mohan

2008-01-01

This study develops a new method of measuring quality of life at the local and state level. Further, it presents a methodology that combines heterogeneous indicators from different fields, such as economics, social, and health, into one total measurement. The technique shown can be used to compare one region with another, or compare one metro area…

Synthesis of Mismatched Heterojunction/Substrate Interfaces

DTIC Science & Technology

1991-10-11

and advantages of strained layers. DD IZ JAN7 1473 EDITION OF INOV 65 IS OBSOLETE *’~~s.*. ~ ~.-A ~’ SECURITY CLASSIFICATIO14 Ol THIS PAGE (When Dsea...cross-section is shown ini 1-ig. 1.14(a), is analogous to the polysilicon -gate FET in Si-MOS devices. From the band diagam in Fig 1.14(b), it can be seen

Correlates of Availability and Accessibility of Fruits and Vegetables in Homes of Low-Income Hispanic Families

ERIC Educational Resources Information Center

Dave, Jayna M.; Evans, Alexandra E.; Pfeiffer, Karin A.; Watkins, Ken W.; Saunders, Ruth P.

2010-01-01

Availability and accessibility (AA) has been consistently shown across studies as the most important correlate of fruits and vegetables (FV) intake. However, there is little data on factors that influence AA of FV, especially in Hispanic families. The objective of this cross-sectional study was to examine the association between parental factors,…

Quality Early Childhood Education in Costa Rica? Policy, Practice, Outcomes and Challenges

ERIC Educational Resources Information Center

San Francisco, Andrea Rolla; Arias, Melissa; Villers, Renata

2005-01-01

High-quality early childhood education has been shown to improve school outcomes in several developing and developed nations. The history of policy around pre-school education in Costa Rica is described as background to presenting cross-sectional data on the emergent literacy skills of low-income Costa Rican children in kindergarten, 1st and 2nd…

The Point of Departure of a Particle Sliding on a Curved Surface

ERIC Educational Resources Information Center

Aghamohammadi, Amir

2012-01-01

A particle is thrown tangentially on a surface. It is shown that for some surfaces and for special initial velocities the thrown particle immediately leaves the surface, and for special conditions it never leaves the surface. The conditions for leaving the surface are investigated. The problem is studied for a surface with the cross-section y =…

Microscopic description of production cross sections including deexcitation effects

NASA Astrophysics Data System (ADS)

Sekizawa, Kazuyuki

2017-07-01

Background: At the forefront of the nuclear science, production of new neutron-rich isotopes is continuously pursued at accelerator laboratories all over the world. To explore the currently unknown territories in the nuclear chart far away from the stability, reliable theoretical predictions are inevitable. Purpose: To provide a reliable prediction of production cross sections taking into account secondary deexcitation processes, both particle evaporation and fission, a new method called TDHF+GEMINI is proposed, which combines the microscopic time-dependent Hartree-Fock (TDHF) theory with a sophisticated statistical compound-nucleus deexcitation model, GEMINI++. Methods: Low-energy heavy ion reactions are described based on three-dimensional Skyrme-TDHF calculations. Using the particle-number projection method, production probabilities, total angular momenta, and excitation energies of primary reaction products are extracted from the TDHF wave function after collision. Production cross sections for secondary reaction products are evaluated employing GEMINI++. Results are compared with available experimental data and widely used grazing calculations. Results: The method is applied to describe cross sections for multinucleon transfer processes in 40Ca+124Sn (Ec .m .≃128.54 MeV ), 48Ca+124Sn (Ec .m .≃125.44 MeV ), 40Ca+208Pb (Ec .m .≃208.84 MeV ), 58Ni+208Pb (Ec .m .≃256.79 MeV ), 64Ni+238U (Ec .m .≃307.35 MeV ), and 136Xe+198Pt (Ec .m .≃644.98 MeV ) reactions at energies close to the Coulomb barrier. It is shown that the inclusion of secondary deexcitation processes, which are dominated by neutron evaporation in the present systems, substantially improves agreement with the experimental data. The magnitude of the evaporation effects is very similar to the one observed in grazing calculations. TDHF+GEMINI provides better description of the absolute value of the cross sections for channels involving transfer of more than one proton, compared to the grazing results. However, there remain discrepancies between the measurements and the calculated cross sections, indicating a limit of the theoretical framework that works with a single mean-field potential. Possible causes of the discrepancies are discussed. Conclusions: To perfectly reproduce experimental cross sections for multinucleon transfer processes, one should go beyond the standard self-consistent mean-field description. Nevertheless, the proposed method will provide valuable information to optimize production mechanisms of new neutron-rich nuclei through its microscopic, nonempirical predictions.

Hyperspherical close-coupling calculations for charge-transfer cross sections in He2++H(1s) collisions at low energies

NASA Astrophysics Data System (ADS)

Liu, Chien-Nan; Le, Anh-Thu; Morishita, Toru; Esry, B. D.; Lin, C. D.

2003-05-01

A theory for ion-atom collisions at low energies based on the hyperspherical close-coupling (HSCC) method is presented. In hyperspherical coordinates the wave function is expanded in analogy to the Born-Oppenheimer approximation where the adiabatic channel functions are calculated with B-spline basis functions while the coupled hyperradial equations are solved by a combination of R-matrix propagation and the slow/smooth variable discretization method. The HSCC method is applied to calculate charge-transfer cross sections for He2++H(1s)→He+(n=2)+H+ reactions at center-of-mass energies from 10 eV to 4 keV. The results are shown to be in general good agreement with calculations based on the molecular orbital (MO) expansion method where electron translation factors (ETF’s) or switching functions have been incorporated in each MO. However, discrepancies were found at very low energies. It is shown that the HSCC method can be used to study low-energy ion-atom collisions without the need to introduce the ad hoc ETF’s, and the results are free from ambiguities associated with the traditional MO expansion approach.

Interpretation of lunar and planetary electromagnetic scattering using the full wave solutions

NASA Technical Reports Server (NTRS)

Bahar, E.; Haugland, M.

1993-01-01

Bistatic radar experiments carried out during the Apollo 14, 15, and 16 missions provide a very useful data set with which to compare theoretical models and experimental data. Vesecky, et al. report that their model for near grazing angles compares favorably with experimental data. However, for angles of incidence around 80 degrees, all the analytical models considered by Vesecky, et al. predict values for the quasi-specular cross sections that are about half the corresponding values taken from the Apollo 16 data. In this work, questions raised by this discrepancy between the reported analytical and experimental results are addressed. The unified full wave solutions are shown to be in good agreement with the bistatic radar taken during Apollo 14 and 16 missions. Using the full wave approach, the quasi-specular contributions to the scattered field from the large scale surface roughness as well as the diffuse Bragg-like scattering from the small scale surface roughness are accounted for in a unified self-consistent manner. Since the full wave computer codes for the scattering cross sections contain ground truth data only, it is shown how it can be reliably used to predict the rough surface parameters of planets based on the measured data.

Determination of the boundary conditions of the grinding load in ball mills

NASA Astrophysics Data System (ADS)

Sharapov, Rashid R.

2018-02-01

The prospects of application in ball mills for grinding cement clinker with inclined partitions are shown. It is noted that ball mills with inclined partitions are more effective. An algorithm is proposed for calculating the power consumed by a ball mill with inclined inter-chamber partitions in which an axial movement of the ball load takes place. The boundary conditions in which the ball load is located are determined. The equations of bounding the grinding load are determined. The behavior of a grinding load is considered in view of the characteristic cross sections. The coordinates of the centers of gravity of the grinding load with a definite step and the shape of the cross sections are determined. It is theoretically shown that grinding load in some parts of the ball mill not only consumes, but also helps to rotate the ball mill. Methods for calculating complex analytical expressions for determining the coordinates of the centers of gravity of the grinding load under the conditions of its longitudinal motion have developed. The carried out researches allow to approach from the general positions to research of behavior of a grinding load in the ball mills equipped with various in-mill devices.

A New Scaling Law of Resonance in Total Scattering Cross Section in Gases

NASA Astrophysics Data System (ADS)

Raju, Gorur Govinda

2009-10-01

Electrical discharges in gases continue to be an active area of research because of industrial applications such as power systems, environmental clean up, laser technology, semiconductor fabrication etc. A fundamental knowledge of electron-gas neutral interaction is indispensable and, the total scattering cross section is one of the quantities that have been measured extensively. The energy dependence of the total cross sections shows peaks or resonance processes that are operative in the collision process. These peaks and the energies at which they occur are shown to satisfy a broad relationship involving the polarizability and the dipole moment of the target particle. Data on 62 target particles belonging to the following species are analyzed. (Eq 1) Rare gas atoms (Eq 2) Di-atomic molecules with combinations of polar, non-polar, attaching, and non-attaching properties Poly-atomic molecules with combinations of polar, non-polar, attaching, and non-attaching properties. Methods of improving the newly identified scaling law and possible application have been identified. 1 INTRODUCTION: Data on electron-neutral interactions are one of the most fundamental in the study of gaseous electronics and an immense literature, both experimental and theoretical, has become available since about the year 1920. [1-5]. In view of the central role which these data play in all facets of gas discharges and plasma science, it is felt that a critical review of available data is timely, mainly for the community of high voltage engineers and industries connected with plasma science in general. The electron-neutral interaction, often referred to as scattering in the scientific literature, is quantified by using the quantity called the total scattering cross section (QT, m^2). In the literature on cross section, total cross section and total scattering cross section are terms used synonymously and we follow the same practice. A definition may be found in reference [1]. This paper concerns scaling of total cross section of gases at resonance energy and the electron energy at which resonance occurs. The meaning of resonance is briefly explained in the following section. Here, we use the term scaling to relate the two quantities mentioned, namely, the resonance energy and the total cross section at that energy. Consistent with the definition of scaling, if the law proposed holds, one of the two quantities mentioned above may be calculated if the other is known. Such a method is very useful in gas discharge modeling and calculation of breakdown voltages, as more fully explained in the later section of the paper. 2 DESCRIPTION OF RESONANCE: A brief description of resonance phenomena in several types of target particles, viz., atomic, poly atomic, polar, non-polar phenomena are presented. 3 PREVIOUS SCALING LAWS: A common representation of a given characteristic with as few adjustable parameters as possible is generally known as the scaling law. The Paschen curve for breakdown voltage is such a familiar scaling law. With reference to cross sections several attempts have been made to obtain a scaling law, with varying degree of success. If the cross section-energy curve is qualitatively similar without having sharp peaks and oscillations, moderately successful scaling laws may be devised. For example, the ionization cross section- energy curves for most gases follow a general pattern. Several published scaling laws are discussed. 4 A NEW SCALING LAW AND DISCUSSION: In this work the author has compiled the resonance details for more than 60 gasest hat include the range from simple atoms to complex molecules that are polyatomic, dipolar, electron-attaching and isomers. The target particles exhibit a number of distinct features, as far as their total cross section variation with electron energy is concerned as already explained.

Implementation of the direct S ( α , β ) method in the KENO Monte Carlo code

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

Hart, Shane W. D.; Maldonado, G. Ivan

The Monte Carlo code KENO contains thermal scattering data for a wide variety of thermal moderators. These data are processed from Evaluated Nuclear Data Files (ENDF) by AMPX and stored as double differential probability distribution functions. The method examined in this study uses S(α,β) probability distribution functions derived from the ENDF data files directly instead of being converted to double differential cross sections. This allows the size of the cross section data on the disk to be reduced substantially amount. KENO has also been updated to allow interpolation in temperature on these data so that problems can be run atmore » any temperature. Results are shown for several simplified problems for a variety of moderators. In addition, benchmark models based on the KRITZ reactor in Sweden were run, and the results are compared with the previous versions of KENO without the direct S(α,β) method. Results from the direct S(α,β) method compare favorably with the original results obtained using the double differential cross sections. Finally, sampling the data increases the run-time of the Monte Carlo calculation, but memory usage is decreased substantially.« less

''Reading'' the photoelectron {beta}-parameter spectrum in a resonance region

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

Dolmatov, V. K.; Guler, E.; Manson, S. T.

2007-09-15

The behavior of the dipole photoelectron angular distribution parameter {beta}{sub nl}({omega}) in the vicinity of autoionizing resonances is discussed. It is shown that from this behavior, surprisingly, many photoionization parameters that cannot be measured experimentally can be extracted. These are the energy positions and ordering of autoionizing resonance minima in the partial photoionization cross sections {sigma}{sub l+1} and {sigma}{sub l-1}, the energies at which these two cross sections intersect, and signs and magnitudes of the cos({delta}{sub l+1}-{delta}{sub l-1}) ({delta}{sub l{+-}}{sub 1} being the phase shifts of the dipole photoionization amplitudes D{sub l{+-}}{sub 1}, respectively) through the autoionizing resonance energy region.more » Based on this, a deeper interpretation of such effects as the width-narrowing, width-fluctuating, and q-reversal in the {beta}{sub nl} parameter spectrum in the autoionizing resonance energy region is given. As an example, calculated data for partial photoionization cross sections {sigma}{sub 3d{r_reversible}}{sub f} and {sigma}{sub 3d{r_reversible}}{sub p}, and {beta}{sub 3d} parameters for 3d photoelectrons from Cr{sup +} are presented.« less

Intrinsic hybrid modes in a corrugated conical horn

NASA Astrophysics Data System (ADS)

Dendane, A.; Arnold, J. M.

1988-08-01

Computational requirements for the generation of intrinsic modes in a nonseparable waveguide geometry requiring a full vector field description with anistropic impedance boundaries were derived. Good agreement is shown between computed and measured radiation patterns in copolar and crosspolar configurations. This agreement establishes that the intrinsic mode correctly accounts for the local normal mode conversion which takes place along the horn in a conventional mode coupling scheme, at least for cone semiangles up to 15 deg. The advantage of the intrinsic mode formulation over the conventional mode-coupling theory is that, to construct a single intrinsic mode throughout the horn, only one local normal mode field is required at each cross section, whereas mode conversion from the HE11 mode would require all the HE1n modes to be known at each cross section. The intrinsic mode accounts also for fields which would appear as backward modes in coupled-mode theory. A complete coupled-mode theory solution requires the inversion of a large matrix at each cross section, whereas the intrinsic mode can be constructed explicitly using a simple Fourier-like integral; the perturbation solution of Dragone (1977) is difficult to make rigorous.

Studying the Permian Cross-section (Volga Region) Using Chemical and Isotopic Investigations

NASA Astrophysics Data System (ADS)

Gareev, B. I.; Batalin, G. A.; Nurgalieva, N. G.; Nourgaliev, D. K.

2016-12-01

This paper presents a study of international important site: the cross-section of Permian system's Urzhumian Stagein the ravine "Pechischy". Outcrop is located on the right bank of the Volga River (about 10 km West of Kazan). Ithas local, regional and planetary correlation features and also footprints of different geographical scale events.The main objective in the research is the deep study of sediments using chemical and isotopic investigations. XRFspectrometer was used for chemical investigations of samples. Chemistry of carbonates and clastic rocks includesthe analysis of chemical elements, compounds, petrochemical (lithogeochemical) modules for the interpretationof the genesis of lithotypes. For the review of the geochemistry of stable isotopes of carbon (oxygen) we usedIRMS. The main objective is the nature of the isotope fractionation issues, to addressing the issues of stratigraphyand paleogeography.The measurements have shown the variability of chemical parameters in cross-section. It gives us opportunity tosee small changes in sedimentation and recognize the factors that influence to the process.The work was carried out according to the Russian Government's Program of Competitive Growth of KazanFederal University, supported by the grant provided to the Kazan State University for performing the state programin the field of scientific research.

Study of inclusive single-jet production in the framework of kt-factorization unintegrated parton distributions

NASA Astrophysics Data System (ADS)

Aminzadeh Nik, R.; Modarres, M.; Masouminia, M. R.

2018-05-01

The present work is intended to study the double-differential cross section of the inclusive single-jet production as the functions of the transverse momentum and the rapidity of the jet in the high-energy hadron-hadron collisions. The angular-ordering-constraint kt-factorization framework is used to calculate the above cross section that is available experimentally. The conditions are taken in accordance with the LHC experiments. The results are compared and analyzed using the existing CMS LHC data. The scheme-dependent unintegrated parton distribution functions (UPDF) of Kimber-Martin-Ryskin (KMR) and Martin-Ryskin-Watt (MRW) in the leading-order and the next-to-leading order (NLO) are used to predict the input partonic UPDF. The utilized phenomenological frameworks prove to be relatively successful in generating satisfactory results compared to the different experiment data, such as CMS (8 and 13 TeV). Extensive discussions and comparisons are made regarding the behavior of the contributing partonic subprocesses. Finally, it is shown that the application of the KMR UPDF to the single-jet differential cross sections have better agreement with the CMS data; on the other hand, they are very similar to those of NLO-MRW.

The reflection of airborne UV laser pulses from the ocean

NASA Technical Reports Server (NTRS)

Hoge, F. E.; Krabill, W. B.; Swift, R. N.

1984-01-01

It is experimentally shown here for the first time that the normalized laser backscatter cross-section of the sea surface is a function of elevation or height position on teh ocean wave. All data were taken off-nadir, resulting in incidence angles of about 6.5 deg measured relative to the normal to mean sea level (MSL). In the limited data sets analyzed to date, the normalized backscatter cross-section was found to be higher in wave crest regions and lower in wave troughs for a swell-dominated sea over which the wind speed was 5 m/s. The reverse was found to be the case for a sea that was driven by a 14 m/s wind. These isolated results show that the MSL, as measured by an off-nadir and/or multibeam type satellite laser altimeter, will be found above, at, or below the true MSL, depending on the local sea conditions existing in the footprint of the altimeter. Airborne nadir-pointed laser altimeter data for a wide variety of sea conditions are needed before a final determination can be made of the effect of sea state on the backscatter cross-section as measured by a down-looking satellite laser system.

Towards a Resolution of the Proton Form Factor Problem: New Electron and Positron Scattering Data

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

Adikaram, D.; Rimal, D.; Weinstein, L. B.

There is a significant discrepancy between the values of the proton electric form factor, GpE, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GpE from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (epsilon) and momentummore » transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ε at Q2=1.45 GeV2. This measurement is consistent with the size of the form factor discrepancy at Q2≈1.75 GeV2 and with hadronic calculations including nucleon and Delta intermediate states, which have been shown to resolve the discrepancy up to 2-3 GeV2.« less

Structural analysis using thrust-fault hanging-wall sequence diagrams: Ogden duplex, Wasatch Range, Utah

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

Schirmer, T.W.

1988-05-01

Detailed mapping and cross-section traverses provide the control for structural analysis and geometric modeling of the Ogden duplex, a complex thrust system exposed in the Wasatch Mountains, east of Ogden, Utah. The structures consist of east-dipping folded thrust faults, basement-cored horses, lateral ramps and folds, and tear faults. The sequence of thrusting determined by means of lateral overlap of horses, thrust-splay relationships, and a top-to-bottom piggyback development is Willard thrust, Ogden thrust, Weber thrust, and Taylor thrust. Major decollement zones occur in the Cambrian shales and limestones. The Tintic Quartzite is the marker for determining gross geometries of horses. Thismore » exposed duplex serves as a good model to illustrate the method of constructing a hanging-wall sequence diagram - a series of longitudinal cross sections that move forward in time and space, and show how a thrust system formed as it moved updip over various footwall ramps. A hanging wall sequence diagram also shows the complex lateral variations in a thrust system and helps to locate lateral ramps, lateral folds, tear faults, and other features not shown on dip-oriented cross sections. 8 figures.« less

Implementation of the direct S ( α , β ) method in the KENO Monte Carlo code

DOE PAGES

Hart, Shane W. D.; Maldonado, G. Ivan

2016-11-25

The Monte Carlo code KENO contains thermal scattering data for a wide variety of thermal moderators. These data are processed from Evaluated Nuclear Data Files (ENDF) by AMPX and stored as double differential probability distribution functions. The method examined in this study uses S(α,β) probability distribution functions derived from the ENDF data files directly instead of being converted to double differential cross sections. This allows the size of the cross section data on the disk to be reduced substantially amount. KENO has also been updated to allow interpolation in temperature on these data so that problems can be run atmore » any temperature. Results are shown for several simplified problems for a variety of moderators. In addition, benchmark models based on the KRITZ reactor in Sweden were run, and the results are compared with the previous versions of KENO without the direct S(α,β) method. Results from the direct S(α,β) method compare favorably with the original results obtained using the double differential cross sections. Finally, sampling the data increases the run-time of the Monte Carlo calculation, but memory usage is decreased substantially.« less

A formula for calculating theoretical photoelectron fluxes resulting from the He/+/ 304 A solar spectral line

NASA Technical Reports Server (NTRS)

Richards, P. G.; Torr, D. G.

1981-01-01

A simplified method for the evaluation of theoretical photoelectron fluxes in the upper atmosphere resulting from the solar radiation at 304 A is presented. The calculation is based on considerations of primary and cascade (secondary) photoelectron production in the two-stream model, where photoelectron transport is described by two electron streams, one moving up and one moving down, and of loss rates due to collisions with neutral gases and thermal electrons. The calculation is illustrated for the case of photoelectrons at an energy of 24.5 eV, and it is noted that the 24.5-eV photoelectron flux may be used to monitor variations in the solar 304 A flux. Theoretical calculations based on various ionization and excitation cross sections of Banks et al. (1974) are shown to be in generally good agreement with AE-E measurements taken between 200 and 235 km, however the use of more recent, larger cross sections leads to photoelectron values a factor of two smaller than observations but in agreement with previous calculations. It is concluded that a final resolution of the photoelectron problem may depend on a reevaluation of the inelastic electron collision cross sections.

Influence of meniscus shape in the cross sectional plane on the knee contact mechanics.

PubMed

Łuczkiewicz, Piotr; Daszkiewicz, Karol; Witkowski, Wojciech; Chróścielewski, Jacek; Zarzycki, Witold

2015-06-01

We present a three dimensional finite element analysis of stress distribution and menisci deformation in the human knee joint. The study is based on the Open Knee model with the geometry of the lateral meniscus which shows some degenerative disorders. The nonlinear analysis of the knee joint under compressive axial load is performed. We present results for intact knee, knee with complete radial posterior meniscus root tear and knee with total meniscectomy of medial or lateral meniscus. We investigate how the meniscus shape in the cross sectional plane influences knee-joint mechanics by comparing the results for flat (degenerated) lateral and normal medial meniscus. Specifically, the deformation of the menisci in the coronal plane and the corresponding stress values in cartilages are studied. By analysing contact resultant force acting on the menisci in axial plane we have shown that restricted extrusion of the torn lateral meniscus can be attributed to small slope of its cross section in the coronal plane. Additionally, the change of the contact area and the resultant force acting on the menisci as the function of compressive load are investigated. Copyright © 2015 Elsevier Ltd. All rights reserved.

Towards a Resolution of the Proton Form Factor Problem: New Electron and Positron Scattering Data

DOE PAGES

Adikaram, D.; Rimal, D.; Weinstein, L. B.; ...

2015-02-10

There is a significant discrepancy between the values of the proton electric form factor, GpE, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GpE from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (epsilon) and momentummore » transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ε at Q2=1.45 GeV2. This measurement is consistent with the size of the form factor discrepancy at Q2≈1.75 GeV2 and with hadronic calculations including nucleon and Delta intermediate states, which have been shown to resolve the discrepancy up to 2-3 GeV2.« less

Towards a resolution of the proton form factor problem: new electron and positron scattering data.

PubMed

Adikaram, D; Rimal, D; Weinstein, L B; Raue, B; Khetarpal, P; Bennett, R P; Arrington, J; Brooks, W K; Adhikari, K P; Afanasev, A V; Amaryan, M J; Anderson, M D; Anefalos Pereira, S; Avakian, H; Ball, J; Battaglieri, M; Bedlinskiy, I; Biselli, A S; Bono, J; Boiarinov, S; Briscoe, W J; Burkert, V D; Carman, D S; Careccia, S; Celentano, A; Chandavar, S; Charles, G; Colaneri, L; Cole, P L; Contalbrigo, M; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dodge, G E; Dupre, R; Egiyan, H; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Filippi, A; Fleming, J A; Fradi, A; Garillon, B; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Gohn, W; Golovatch, E; Gothe, R W; Griffioen, K A; Guegan, B; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Harrison, N; Hattawy, M; Hicks, K; Holtrop, M; Hughes, S M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Jenkins, D; Jiang, H; Jo, H S; Joo, K; Joosten, S; Kalantarians, N; Keller, D; Khandaker, M; Kim, A; Kim, W; Klein, A; Klein, F J; Koirala, S; Kubarovsky, V; Kuhn, S E; Livingston, K; Lu, H Y; MacGregor, I J D; Markov, N; Mattione, P; Mayer, M; McKinnon, B; Mestayer, M D; Meyer, C A; Mirazita, M; Mokeev, V; Montgomery, R A; Moody, C I; Moutarde, H; Movsisyan, A; Camacho, C Munoz; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Peña, C; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Puckett, A J R; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatié, F; Salgado, C; Schott, D; Schumacher, R A; Seder, E; Sharabian, Y G; Simonyan, A; Skorodumina, I; Smith, E S; Smith, G D; Sober, D I; Sokhan, D; Sparveris, N; Stepanyan, S; Stoler, P; Strauch, S; Sytnik, V; Taiuti, M; Tian, Ye; Trivedi, A; Ungaro, M; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Wei, X; Wood, M H; Zachariou, N; Zana, L; Zhang, J; Zhao, Z W; Zonta, I

2015-02-13

There is a significant discrepancy between the values of the proton electric form factor, G(E)(p), extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of G(E)(p) from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (ϵ) and momentum transfer (Q(2)) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ϵ at Q(2)=1.45  GeV(2). This measurement is consistent with the size of the form factor discrepancy at Q(2)≈1.75  GeV(2) and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2-3  GeV(2).

Survival bias and drug interaction can attenuate cross-sectional case-control comparisons of genes with health outcomes. An example of the kinesin-like protein 6 (KIF6) Trp719Arg polymorphism and coronary heart disease.

PubMed

Williams, Paul; Pendyala, Lakshmana; Superko, Robert

2011-03-24

Case-control studies typically exclude fatal endpoints from the case set, which we hypothesize will substantially underestimate risk if survival is genotype-dependent. The loss of fatal cases is particularly nontrivial for studies of coronary heart disease (CHD) because of significantly reduced survival (34% one-year fatality following a coronary attack). A case in point is the KIF6 Trp719Arg polymorphism (rs20455). Whereas six prospective studies have shown that carriers of the KIF6 Trp719Arg risk allele have 20% to 50% greater CHD risk than non-carriers, several cross-sectional case-control studies failed to show that carrier status is related to CHD. Computer simulations were therefore employed to assess the impact of the loss of fatal events on gene associations in cross-sectional case-control studies, using KIF6 Trp719Arg as an example. Ten replicates of 1,000,000 observations each were generated reflecting Canadian demographics. Cardiovascular disease (CVD) risks were assigned by the Framingham equation and events distributed among KIF6 Trp719Arg genotypes according to published prospective studies. Logistic regression analysis was used to estimate odds ratios between KIF6 genotypes. Results were examined for 33%, 41.5%, and 50% fatality rates for incident CVD.In the absence of any difference in percent fatalities between genotypes, the odds ratios (carriers vs. noncarriers) were unaffected by survival bias, otherwise the odds ratios were increasingly attenuated as the disparity between fatality rates increased between genotypes. Additional simulations demonstrated that statin usage, shown in four clinical trials to substantially reduce the excess CHD risk in the KIF6 719Arg variant, should also attenuate the KIF6 719Arg odds ratio in case-control studies. These computer simulations show that exclusions of prior CHD fatalities attenuate odds ratios of case-control studies in proportion to the difference in the percent fatalities between genotypes. Disproportionate CHD survival for KIF6 Trip719Arg carriers is suggested by their 50% greater risk for recurrent myocardial infarction. This, and the attenuation of KIF6 719Arg carrier risk with statin use, may explain the genotype's weak association with CHD in cross-sectional case-control studies. The results may be relevant to the underestimation of risk in cross-sectional case-control studies of other genetic CHD-risk factors affecting survival.

Prediction of static aerodynamic characteristics for slender bodies alone and with lifting surfaces to very high angles of attack

NASA Technical Reports Server (NTRS)

Jorgensen, L. H.

1977-01-01

An engineering-type method is presented for computing normal-force and pitching-moment coefficients for slender bodies of circular and noncircular cross section alone and with lifting surfaces. In this method, a semi-empirical term representing viscous-separation crossflow is added to a term representing potential-theory crossflow. For many bodies of revolution, computed aerodynamic characteristics are shown to agree with measured results for investigated free-stream Mach numbers from 0.6 to 2.9. The angles of attack extend from 0 deg to 180 deg for M = 2.9 from 0 deg to 60 deg for M = 0.6 to 2.0. For several bodies of elliptic cross section, measured results are also predicted reasonably well over the investigated Mach number range from 0.6 to 2.0 and at angles of attack from 0 deg to 60 deg. As for the bodies of revolution, the predictions are best for supersonic Mach numbers. For body-wing and body-wing-tail configurations with wings of aspect ratios 3 and 4, measured normal-force coefficients and centers are predicted reasonably well at the upper test Mach number of 2.0. Vapor-screen and oil-flow pictures are shown for many body, body-wing and body-wing-tail configurations. When spearation and vortex patterns are asymmetric, undesirable side forces are measured for the models even at zero sideslip angle. Generally, the side-force coefficients decrease or vanish with the following: increase in Mach number, decrease in nose fineness ratio, change from sharp to blunt nose, and flattening of body cross section (particularly the body nose).

Near-threshold J/ψ-meson photoproduction on nuclei

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

Paryev, E. Ya.; Kiselev, Yu. T., E-mail: yurikis@itep.ru

On the basis of the first-collision model that relies on the nuclear spectral function and which includes incoherent processes involving charmonium production in proton–nucleon collisions, the photoproduction of J/ψ mesons on nuclei is considered at energies close to the threshold for their production on a nucleon. The absorption of final J/ψ mesons, their formation length, and the binding and Fermi motion of target nucleons are taken into account in this model along with the effect of the nuclear potential on these processes. The A dependences of the absolute and relative charmonium yields are calculated together with absolute and relative excitationmore » functions under various assumptions on the magnitude of the cross section for J/ψN absorption, the J/ψ-meson formation length, and their inmedium modification. It is shown that, at energies above the threshold, these features are virtually independent of the formation length and the change in the J/ψ-meson mass in nuclear matter but are rather highly sensitive to the cross section for J/ψN interaction. The calculations performed in the present study can be used to determine the unknown cross section for J/ψ-meson absorption in nuclei from a comparison of their results with data expected from experiments in the Hall C of the CEBAF (USA) facility upgraded to the energy of 12 GeV. It is also shown that the absolute and relative excitation functions for J/ψ mesons in photon–nucleus reactions at subthreshold energies are sensitive to the change in the meson mass and, hence, carry information about the properties of charmonium in nuclear matter.« less

Investigation of Kp- and Kd-atom formation and their collisional processes with hydrogen and deuterium targets by the classical-trajectory Monte Carlo method

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

Raeisi, G. M.; Department of Physics, Shahrekord University, Shahrekord 115; Kalantari, S. Z.

The classical-trajectory Monte Carlo method has been used to study the capture of negative kaons by hydrogen and deuterium atoms; subsequently, the elastic scattering, Stark mixing, and Coulomb deexcitation cross sections of Kp and Kd atoms have been determined. The results for kaonic atom formation confirm the initial conditions that have been parametrically applied by most atomic cascade models. Our results show that Coulomb deexcitation in Kp and Kd atoms with {Delta}n>1 is important in addition to n=1. We have shown that the contribution of molecular structure effects to the cross sections of the collisional processes is larger than themore » isotopic effects of the targets. We have also compared our results with the semiclassical approaches.« less

Production of the Q2 doubly excited states of the hydrogen molecule by electron impact in a single step

NASA Astrophysics Data System (ADS)

Santos, Leonardo O.; Rocha, Alexandre B.; Faria, Nelson Velho de Castro; Jalbert, Ginette

2017-03-01

We calculate the single step cross sections for excitation of Q 2 states of H2 and its subsequent dissociation. The cross section calculations were performed within the first Born approximation and the electronic wave functions were obtained via State-Averaged Multiconfigurational Self-Consistent Field followed by Configuration Interaction. We have assumed autoionization is the only important process competing with dissociation into neutral atoms. We have estimated its probability through a semi classical approach and compared with results of literature. Special attention was given to the Q 2 1Σg +(1) state which, as has been shown in a previous work, may dissociate into H(2 sσ) + H(2 sσ) fragments (some figures in this article are in colour only in the electronic version).

An improved target velocity sampling algorithm for free gas elastic scattering

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

Romano, Paul K.; Walsh, Jonathan A.

We present an improved algorithm for sampling the target velocity when simulating elastic scattering in a Monte Carlo neutron transport code that correctly accounts for the energy dependence of the scattering cross section. The algorithm samples the relative velocity directly, thereby avoiding a potentially inefficient rejection step based on the ratio of cross sections. Here, we have shown that this algorithm requires only one rejection step, whereas other methods of similar accuracy require two rejection steps. The method was verified against stochastic and deterministic reference results for upscattering percentages in 238U. Simulations of a light water reactor pin cell problemmore » demonstrate that using this algorithm results in a 3% or less penalty in performance when compared with an approximate method that is used in most production Monte Carlo codes« less

An improved target velocity sampling algorithm for free gas elastic scattering

DOE PAGES

Romano, Paul K.; Walsh, Jonathan A.

2018-02-03

We present an improved algorithm for sampling the target velocity when simulating elastic scattering in a Monte Carlo neutron transport code that correctly accounts for the energy dependence of the scattering cross section. The algorithm samples the relative velocity directly, thereby avoiding a potentially inefficient rejection step based on the ratio of cross sections. Here, we have shown that this algorithm requires only one rejection step, whereas other methods of similar accuracy require two rejection steps. The method was verified against stochastic and deterministic reference results for upscattering percentages in 238U. Simulations of a light water reactor pin cell problemmore » demonstrate that using this algorithm results in a 3% or less penalty in performance when compared with an approximate method that is used in most production Monte Carlo codes« less

Surgical tool alignment guidance by drawing two cross-sectional laser-beam planes.

PubMed

Nakajima, Yoshikazu; Dohi, Takeyoshi; Sasama, Toshihiko; Momoi, Yasuyuki; Sugano, Nobuhiko; Tamura, Yuichi; Lim, Sung-hwan; Sakuma, Ichiro; Mitsuishi, Mamoru; Koyama, Tsuyoshi; Yonenobu, Kazuo; Ohashi, Satoru; Bessho, Masahiko; Ohnishi, Isao

2013-06-01

Conventional surgical navigation requires for surgeons to move their sight and conscious off the surgical field when checking surgical tool's positions shown on the display panel. Since that takes high risks of surgical exposure possibilities to the patient's body, we propose a novel method for guiding surgical tool position and orientation directly in the surgical field by a laser beam. In our navigation procedure, two cross-sectional planar laser beams are emitted from the two laser devices attached onto both sides of an optical localizer, and show surgical tool's entry position on the patient's body surface and its orientation on the side face of the surgical tool. In the experiments, our method gave the surgeons precise and accurate surgical tool adjusting and showed the feasibility to apply to both of open and percutaneous surgeries.

High energy γ-ray production from Be, C, and Al targets with 65 MeV 3He bombardment

NASA Astrophysics Data System (ADS)

Hosaka, M.; Ishii, K.; Ohura, M.; Terakawa, A.; Miyamoto, S.; Guan, Z.; Orihara, H.; Kasagi, J.

1996-11-01

High-energy γ rays from targets of Be, C, and Al bombarded with 65 MeV 3He ions have been measured by the use of a γ-ray detector system consisting of seven BaF2 scintillators. The energy spectra were obtained up to the maximum energy kinematically permitted in each collision at detection angles of 35°-144°. The experimental cross sections are compared with calculations of the potential bremsstrahlung on which the theory has been developed by Nakayama and Bertsch. It is shown that the prediction of potential bremsstrahlung can well reproduce the production cross sections of γ rays of energy near the kinematical maximum energy in collisions, while this result is contrary to the previous one of Tam et al. in α and d bombardments.

Quasi-elastic electroproduction of charged ρ -mesons on nucleons

NASA Astrophysics Data System (ADS)

Sviridova, L. L.; Fedorov, D. K.; Neudatchin, V. G.; Obukhovsky, I. T.; Faessler, A.

2010-06-01

The electroproduction of charged ρ -mesons on the nucleon at intermediate energy is discussed for quasi-elastic kinematics. It is shown that at these kinematics both the longitudinal σ_{{L}}^{} and transverse σ_{{T}}^{} cross-sections are dominated by the ρ -meson t -pole contribution, and thus the corresponding dσ L( T)/d t data can give a valuable information on the ρ -meson component of the nucleon cloud. The differential cross-sections for the reaction p( e, e ' ρ+_{}) n at Q 2 = 2 , 3.5GeV^2 and at the invariant mass W = 3 and 4GeV are calculated on the basis of quasi-elastic knockout mechanism with form factors. Questions about the gauge invariance of the electroproduction amplitude are considered and it is noted an important difference between photo- and electroproduction amplitudes.

Ballasting pipeline moving in horizontal well as method of control sticking phenomenon

NASA Astrophysics Data System (ADS)

Toropov, V. S.; Toropov, E. S.

2018-05-01

The mechanism of the phenomenon of sticking a pipeline moving in a well while pulled by the facility horizontal directional drilling is investigated. A quantitative evaluation of the force arising from sticking is given. At the same time, the working hypothesis takes a view of the combined effect of adhesion and friction interactions as the reasons that cause this phenomenon. As a measure to control the occurrence of sticking and to reduce the resistance force to movement of the pipeline in the well, several methods of ballasting the working pipeline are proposed, depending on the profile of the well and the ratio of the length of the curved sections of the inlet and outlet and the straight horizontal sections of the profile. It is shown that for crossings, which profile contains an extended horizontal section, it is possible to partially fill the pipeline with water to achieve zero buoyancy, and for crossings with curvature along the entire profile, the ballasting efficiency will be minimal.

An MHD simulation of By-dependent magnetospheric convection and field-aligned currents during northward IMF

NASA Technical Reports Server (NTRS)

Ogino, T.; Walker, R. J.; Ashour-Abdalla, M.; Dawson, J. M.

1985-01-01

A three-dimensional MHD simulation code is used to model the magnetospheric configuration when the IMF has both a northward B(z) component and a B(y) component in the east-west direction. Projections of the plasma pressure, the field-aligned velocity, the field-aligned vorticity, and the field-aligned current along the magnetic field lines into the northern ionosphere are shown and discussed. Cross-sectional patterns of these parameters are shown. The results demonstrate that the B(y) component of the IMF strongly influences the plasma sheet configuration and the magnetospheric convection pattern.

The effect of ring distortions on buckling of blunt conical shells. [Viking mission aeroshell

NASA Technical Reports Server (NTRS)

Heard, W. L., Jr.; Anderson, M. S.; Stephens, W. B.

1975-01-01

A rigorous analytical study of cones stiffened by many thin-gage, open-section rings is presented. The results are compared with data previously obtained from uniform pressure tests of the Viking mission flight aeroshell and of the Viking structural prototype aeroshells. A conventional analysis, in which the rings are modeled as discrete rigid cross sections, is shown to lead to large, unconservative strength predictions. A more sophisticated technique of modeling the rings as shell branches leads to much more realistic strength predictions and more accurately predicts the failure modes. It is also shown that if a small initial imperfection proportional to the shape of the buckling mode is assumed, the critical buckling modes from analysis and test are in agreement. However, the reduction in buckling strength from the perfect-shell predictions is small.

Geologic map of the Khanneshin carbonatite complex, Helmand Province, Afghanistan, modified from the 1976 original map compilation of V.G. Cheremytsin

USGS Publications Warehouse

Tucker, Robert D.; Peters, Stephen G.; Schulz, Klaus J.; Renaud, Karine M.; Stettner, Will R.; Masonic, Linda M.; Packard, Patricia H.

2011-01-01

This map is a modified version of the Geological map of the Khanneshin carbonatite complex, scale 1:10,000, which was compiled by V.G. Cheremytsin in 1976. Scientists from the U.S. Geological Survey, in cooperation with the Afghan Geological Survey and the Task Force for Business and Stability Operations of the U.S. Department of Defense, studied the original map and also visited the field area in September 2009, August 2010, and February 2011. This modified map, which includes cross sections, illustrates the geologic structure of the Khanneshin carbonatite complex. The map reproduces the topology (contacts, faults, and so forth) of the original Soviet map and cross sections and includes modifications based on our examination of that map and a related report, and based on observations made during our field visits. (Refer to the References section in the Map PDF for complete citations of the original map and related report.) Elevations on the cross section are derived from the original Soviet topography and may not match the newer topography used on the current map. We have attempted to translate the original Russian terminology and rock classification into modern English geologic usage as literally as possible without changing any genetic or process-oriented implications in the original descriptions. We also use the age designations from the original map. The unit colors on the map and cross sections differ from the colors shown on the original version. The units are colored according to the color and pattern scheme of the Commission for the Geological Map of the World (CGMW) (http://www.ccgm.org).

Geologic map of the western Haji-Gak iron deposit, Bamyan Province, Afghanistan, modified from the 1965 original map compilation of V.V. Reshetniak and I.K. Kusov

USGS Publications Warehouse

Renaud, Karine M.; Tucker, Robert D.; Peters, Stephen G.; Stettner, Will R.; Masonic, Linda M.; Moran, Thomas W.

2011-01-01

This map is a modified version of Geologic-prospecting plan of western area of Hajigak iron-ore deposit, scale 1:2,000, which was compiled by V.V. Reshetniak and I.K. Kusov in 1965. (Refer to the References Cited section in the Map PDF for complete citations of the original map and related reports.) USGS scientists, in cooperation with the Afghan Geological Survey and the Task Force for Business and Stability Operations of the U.S. Department of Defense, studied the original documents and also visited the field area in November 2009. This modified map illustrates the geological structure of the western Haji-Gak iron deposit and includes cross sections of the same area. The map reproduces the topology (contacts, faults, and so forth) of the original Soviet map and includes modifications based on our examination of that document. We constructed the cross sections from data derived from the original map. Elevations on the cross sections are derived from the original Soviet topography and may not match the newer topography used on the current map. We have attempted to translate the original Russian terminology and rock classification into modern English geologic usage as literally as possible without changing any genetic or process-oriented implications in the original descriptions. We also use the age designations from the original map. The unit colors on the map and cross sections differ from the colors shown on the original version. The units are colored according to the color and pattern scheme of the Commission for the Geological Map of the World (CGMW) (http://www.ccgm.org).

Spontaneous progression of vertebral intraosseous pneumatocysts to fluid-filled cysts.

PubMed

Nakayama, T; Ehara, S; Hama, H

2001-09-01

Intraosseous pneumatocyst is a relatively rare condition, and its natural course is not known. We report two cases of intraosseous pneumatocyst of vertebra with resorption of gas and its replacement with fluid shown on follow-up cross-sectional imaging. The mechanism influencing the course of these appearances is unclear. However, the benign nature of intraosseous pneumatocyst needs to be recognized and biopsy avoided.

Assessment of Pilot Needs for Shipboard Data and Informational Documents

DTIC Science & Technology

1990-03-01

may differ from that shown on the poster due to environmental , hull and loading conditions. 3.3 Manoeuvring booklet (appendix 3) The manoeuvring...familiarize a broad cross-section of pilots with International Maritime Organization (IMO) proposals for pilot cards and wheelhouse posters and the...through the National Technical Informa- wheelhouse poster tion Service, Springfield, VA 22161 ship pilots. 19. Security Clasaif. (of this report) 20

Power law relationships for rain attenuation and reflectivity

NASA Technical Reports Server (NTRS)

Devasirvatham, D. M. J.; Hodge, D. B.

1978-01-01

The equivalent reflectivity, specific attenuation and volumetric backscatter cross section of rain are calculated and tabulated at a number of frequencies from 1 to 500 GHz using classical Mie theory. The first two parameters are shown to be closely approximated as functions of rain rate by the power law aR to the b power. The a's and b's are also tabulated and plotted for convenient reference.

The Effects of Armed Conflict on Schooling in Sub-Saharan Africa

ERIC Educational Resources Information Center

Poirier, Thomas

2012-01-01

In the past decades, most of the countries in Sub-Saharan Africa have been affected by armed conflicts. By means of a time-series cross-sectional (TSCS) database, we attempt to measure the impact of war on a sample of 43 countries in Africa from 1950 to 2010. These conflicts, and especially civil wars, are shown to have a strong negative effect on…

Energy-loss cross sections for inclusive charge-exchange reactions at intermediate energies

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.; Townsend, Lawrence W.; Dubey, Rajendra R.

1993-01-01

Charge-exchange reactions for scattering to the continuum are considered in a high-energy multiple scattering model. Calculations for (p,n) and (He-3,H-3) reactions are made and compared with experimental results for C-12, O-16, and Al-27 targets. Coherent effects are shown to lead to an important role for inelastic multiple scattering terms when light projectiles are considered.

The vibrational dependence of dissociative recombination: Rate constants for N{sub 2}{sup +}

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

Guberman, Steven L., E-mail: slg@sci.org

Dissociative recombination rate constants are reported with electron temperature dependent uncertainties for the lowest 5 vibrational levels of the N{sub 2}{sup +} ground state. The rate constants are determined from ab initio calculations of potential curves, electronic widths, quantum defects, and cross sections. At 100 K electron temperature, the rate constants overlap with the exception of the third vibrational level. At and above 300 K, the rate constants for excited vibrational levels are significantly smaller than that for the ground level. It is shown that any experimentally determined total rate constant at 300 K electron temperature that is smaller thanmore » 2.0 × 10{sup −7} cm{sup 3}/s is likely to be for ions that have a substantially excited vibrational population. Using the vibrational level specific rate constants, the total rate constant is in very good agreement with that for an excited vibrational distribution found in a storage ring experiment. It is also shown that a prior analysis of a laser induced fluorescence experiment is quantitatively flawed due to the need to account for reactions with unknown rate constants. Two prior calculations of the dissociative recombination rate constant are shown to be inconsistent with the cross sections upon which they are based. The rate constants calculated here contribute to the resolution of a 30 year old disagreement between modeled and observed N{sub 2}{sup +} ionospheric densities.« less

Optimization of Production Lines and Cross-sections of Fiberglass Rebar

NASA Astrophysics Data System (ADS)

Maksimov, S. P.; Dildin, A. N.; Maksimova, A. E.

2017-11-01

The article substantiates the need of the construction industry in new lightweight and durable materials that ensure reduction in the cost of work and increase in the operational characteristics of the constructed facilities. These materials include fiberglass reinforcement which is an auxiliary bar made of heavy-duty glass fibers impregnated with a polymer adhesive composition and additionally entwined to create a ribbed surface and tight fit with fiberglass threads. This fitting has undeniable advantages in comparison with steel fittings. The polymer composite is resistant to corroding medium, does not corrode, does not conduct electricity, has high elastic properties, low thermal conductivity, increased tensile strength, etc. It is shown that the issues related to the improvement of technology and the form of a fiberglass rebar section are relevant for the construction industry. So, in particular, the presented developments will significantly reduce the consumption of adhesive composition for impregnating roving threads, reduce production costs by eliminating the loss of adhesive composition in impregnating vessels and pull-guide rollers, increasing the environmental friendliness of production and increasing the line productivity. In addition, it is possible to improve the strength characteristics by optimizing the cross-section and longitudinal cross-sections of the resulting fiberglass reinforcement. The presented changes in the design and technology of fiberglass reinforcement production can be realized as a separate independent module. It is easy to integrate into existing lines during repair work or routine maintenance of equipment.

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

Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru; Kostryukov, P. V.

It is shown that a quantum system whose Hamiltonian is independent of time is T -invariant if this Hamiltonian contains only those terms that do not change sign upon time reversal. It is also shown that the coincidence of the amplitudes for multistep direct and statistical nuclear reactions with the timereversed amplitudes for the reactions being studied is a condition that ensures the T -invariance of the amplitudes in question, the transition from the original amplitudes to their time-reversed counterparts being accomplished, first, upon introducing the inverse-reactionmatrices T instead of the original-reaction matrix T and, second, upon replacing the wavemore » functions for the initial, final, and intermediate states of the system by the respective time-reversed functions. It is found that the T -even (T -odd) asymmetries in cross sections for nuclear reactions stem from the interference between the amplitudes characterizing these reactions and having identical (opposite) T -parities. It is shown that the T -invariance condition for the above T -even (T -odd) asymmetries is related to the conservation of (change in) the sign of these asymmetries upon going over from original to inverse nuclear reactions. Mechanisms underlying the appearance of possible T -even and T-odd asymmetries in the cross sections for the cold-polarizedneutron- induced binary and ternary fission of oriented target nuclei are analyzed for the case of employing T -invariant Hamiltonians for the systems under study. It is also shown that the asymmetries in question satisfy the T -invariance condition if the reactions being considered have a sequential multistep statistical character. It is concluded that T -invariance is violated in the limiting case where, in ternary nuclear fission, the emission of a light third particle froma fissile compound nucleus formed upon incident-neutron capture by a target nucleus and its separation to two fission fragments are simultaneous events.« less

Geometric effects on electrocapillarity in nanochannels with an overlapped electric double layer.

PubMed

Lee, Jung A; Kang, In Seok

2016-10-01

Unsteady filling of electrolyte solution inside a nanochannel by the electrocapillarity effect is studied. The filling rate is predicted as a function of the bulk concentration of the electrolyte, the surface potential (or surface charge density), and the cross sectional shape of the channel. For a nanochannel, the average outward normal stress exerted on the cross section of a channel (P[over ¯]_{zz}^{}) can be regarded as a measure of electrocapillarity and it is the driving force of the flow. This electrocapillarity measure is first analyzed by using the solution of the Poisson-Boltzmann equation. From the analysis, it is found that the results for many different cross sectional shapes can be unified with good accuracy if the hydraulic radius is adopted as the characteristic length scale of the problem. Especially in the case of constant surface potential, for both limits of κh→0 and κh→∞, it can be shown theoretically that the electrocapillarity is independent of the cross sectional shape if the hydraulic radius is the same. In order to analyze the geometric effects more systematically, we consider the regular N-polygons with the same hydraulic radius and the rectangles of different aspect ratios. Washburn's approach is then adopted to predict the filling rate of electrolyte solution inside a nanochannel. It is found that the average filling velocity decreases as N increases in the case of regular N-polygons with the same hydraulic radius. This is because the regular N-polygons of the same hydraulic radius share the same inscribing circle.

Geologic cross sections showing the concentrations of As, Cd, Co, Cu, Cr, Fe, Mo, Ni, Pb, and Zn in acid-insoluble residues of Paleozoic rocks within the Doniphan/Eleven Point Ranger District of the Mark Twain National Forest, Missouri, USA

USGS Publications Warehouse

Lee, Lopaka; Goldhaber, Martin B.

2002-01-01

This report is a product of a U.S. Geological Survey investigation that is focused on characterizing the potential environmental impacts of lead-zinc mining within the Doniphan/Eleven Point ranger district of the Mark Twain national forest. The elemental concentrations of iron (Fe), arsenic (As), cadmium (Cd), cobalt (Co), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), and zinc (Zn) in acidinsoluble residues are shown for boreholes along two geologic cross sections within Doniphan/Elevan Point ranger district (Figure 1). The purpose of this report is to characterize, in a general sense, the distribution of economically and environmentally important elements within the rocks and aquifers of the Doniphan/Eleven Point ranger district

Effect of chronic centrifugation of the musculoskeletal system of the dog.

PubMed

Amtmann, E; Oyama, J; Fisher, G L

1976-04-21

Sixteen male Beagle dogs, 293 to 509 days old, were exposed almost continuously for 3 months to 2.0 G on a 7.9 meter radius centrifuge. The dogs were maintained on the centrifuge, by means of a specially designed automated waste disposal and life support system. As compared to the mean values of normal gravity controls, centrifuged dogs showed no differences in femur length; cross-sectional area, outer and inner radii at mid-shaft of the femur; dry weights of the biceps femoris, quadriceps femoris, and gastrocnemius muscles. It was shown by analysis of covariance that chronic centrifugation has no effect on the relationship between the length and the cross-sectional dimensions at mid-shaft of the femur. Photon absorptiometry, however, revealed significant mineral content increases averaging 1.5% at 3 sites, i.e., at the 1/4, 1/2 and 3/4 length of the femur.

Part-body and multibody effects on absorption of radio-frequency electromagnetic energy by animals and by models of man

NASA Technical Reports Server (NTRS)

Gandhi, O. P.; Hagmann, M. J.; Dandrea, J. A.

1979-01-01

Fine structure in the whole-body resonant curve for radio-frequency energy deposition in man can be attributed to part-body resonances. As for head resonance, which occurs near 350 MHz in man, the absorptive cross section is nearly three times the physical cross section of the head. The arm has a prominent resonance at 150 MHz. Numerical solutions, antenna theory, and experimental results on animals have shown that whole-body energy deposition may be increased by 50 percent or more because of multiple bodies that are strategically located in the field. Empirical equations for SARs are also presented along with test data for several species of laboratory animals. Barbiturate anesthesia is sufficiently disruptive of thermoregulation that delta Ts of colonic temperature yield energy dose values in several mammals that compare quite favorably with those based on whole-body calorimetry.

Mode propagation in optical nanowaveguides with dielectric cores and surrounding metal layers.

PubMed

Lapchuk, Anatoly S; Shin, Dongho; Jeong, Ho-Seop; Kyong, Chun Su; Shin, Dong-Ik

2005-12-10

The mode spectrum in an optical nanowaveguide consisting of a dielectric-core layer surrounded by two identical metal layers is investigated. A simple model based on mode matching to predict the properties of mode propagation in such optical nanowaveguides is proposed. It is shown that quasi-TM00 and quasi-TM10 modes supported by an optical microstrip line do not have a cutoff frequency, regardless of the size of the metal strips, the thickness of the dielectric slab, and the cross-sectional shape. The transverse size of the TM00 mode supported by a nanosized microstrip line was found to be approximately equal to the transverse dimension of the microstrip line. In closed rectangular and elliptical nanowaveguides, i.e., in which all dielectric surfaces are covered with metal films, the cross-sectional shape of the waveguide should be stretched along one side to produce propagation conditions for the fundamental mode.

Perspectives of cross-sectional scanning tunneling microscopy and spectroscopy for complex oxide physics

NASA Astrophysics Data System (ADS)

Wang, Aaron; Chien, TeYu

2018-03-01

Complex oxide heterostructure interfaces have shown novel physical phenomena which do not exist in bulk materials. These heterostructures can be used in the potential applications in the next generation devices and served as the playgrounds for the fundamental physics research. The direct measurements of the interfaces with excellent spatial resolution and physical property information is rather difficult to achieve with the existing tools. Recently developed cross-sectional scanning tunneling microscopy and spectroscopy (XSTM/S) for complex oxide interfaces have proven to be capable of providing local electronic density of states (LDOS) information at the interface with spatial resolution down to nanometer scale. In this perspective, we will briefly introduce the basic idea and some recent achievements in using XSTM/S to study complex oxide interfaces. We will also discuss the future of this technique and the field of the interfacial physics.

Theoretical and Experimental Triple Differential Cross Sections for Electron Impact Ionization of SF6

NASA Astrophysics Data System (ADS)

Chaluvadi, Hari; Nixon, Kate; Murray, Andrew; Ning, Chuangang; Colgan, James; Madison, Don

2014-10-01

Experimental and theoretical Triply Differential Cross Sections (TDCS) will be presented for electron-impact ionization of sulfur hexafluoride (SF6) for the molecular orbital 1t1g. M3DW (molecular 3-body distorted wave) results will be compared with experiment for coplanar geometry and for perpendicular plane geometry (a plane which is perpendicular to the incident beam direction). In both cases, the final state electron energies and observation angles are symmetric and the final state electron energies range from 5 eV to 40 eV. It will be shown that there is a large difference between using the OAMO (orientation averaged molecular orbital) approximation and the proper average over all orientations and also that the proper averaged results are in much better agreement with experiment. Work supported by NSF under Grant Number PHY-1068237. Computational work was performed with Institutional resources made available through Los Alamos National Laboratory.

NEAMS Update. Quarterly Report for January - March 2014

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

Stan, Marius

2014-08-01

This quarterly report covers the following points: A fully three-dimensional smeared cracking model has been implemented and tested in BISON; DAKOTA-BISON was used to study the parameters that govern heat transfer across the fuel-cladding; Calculations of grain boundary mobility in UO 2 have been extended to high temperatures; Mesh adaptivity is being employed in MARMOT simulations to increase computational efficiency; Molecular dynamics simulations have shown correlation between atomic displacements and the anisotropic thermal conductivity in UO 2; The SHARP team continues to address the application of the toolkit to assembly deformations driven by reactivity feedback; The Nek5000 team has extendedmore » the low-Machnumber capability to mixtures with multiple species; The generalized cross section library has been tested for various fuel assemblies and reactor types; and The subgroup cross-section interface was successfully implemented in PROTEUS-SN (page 6).« less

Use of boron nitride for neutron spectrum characterization and cross-section validation in the epithermal range through integral activation measurements

NASA Astrophysics Data System (ADS)

Radulović, Vladimir; Trkov, Andrej; Jaćimović, Radojko; Gregoire, Gilles; Destouches, Christophe

2016-12-01

A recent experimental irradiation and measurement campaign using containers made from boron nitride (BN) at the Jožef Stefan Institute (JSI) TRIGA Mark II reactor in Ljubljana, Slovenia, has shown the applicability of BN for neutron spectrum characterization and cross-section validation in the epithermal range through integral activation measurements. The first part of the paper focuses on the determination of the transmission function of a BN container through Monte Carlo calculations and experimental measurements. The second part presents the process of tayloring the sensitivity of integral activation measurements to specific needs and a selection of suitable radiative capture reactions for neutron spectrum characterization in the epithermal range. A BN container used in our experiments and its qualitative effect on the neutron spectrum in the irradiation position employed is displayed in the Graphical abstract.

Family members' satisfaction with care and decision-making in intensive care units and post-stay follow-up needs-a cross-sectional survey study.

PubMed

Frivold, Gro; Slettebø, Åshild; Heyland, Daren K; Dale, Bjørg

2018-01-01

The aim of this study was to explore family members' satisfaction with care and decision-making during the intensive care units stay and their follow-up needs after the patient's discharge or death. A cross-sectional survey study was conducted. Family members of patients recently treated in an ICU were participating. The questionnaire contented of background variables, the instrument Family Satisfaction in ICU (FS-ICU 24) and questions about follow-up needs. Descriptive and non-parametric statistics and a multiple linear regression were used in the analysis. A total of 123 (47%) relatives returned the questionnaire. Satisfaction with care was higher scored than satisfaction with decision-making. Follow- up needs after the ICU stay was reported by 19 (17%) of the participants. Gender and length of the ICU stay were shown as factors identified to predict follow-up needs.

Review of FD-TD numerical modeling of electromagnetic wave scattering and radar cross section

NASA Technical Reports Server (NTRS)

Taflove, Allen; Umashankar, Korada R.

1989-01-01

Applications of the finite-difference time-domain (FD-TD) method for numerical modeling of electromagnetic wave interactions with structures are reviewed, concentrating on scattering and radar cross section (RCS). A number of two- and three-dimensional examples of FD-TD modeling of scattering and penetration are provided. The objects modeled range in nature from simple geometric shapes to extremely complex aerospace and biological systems. Rigorous analytical or experimental validatons are provided for the canonical shapes, and it is shown that FD-TD predictive data for near fields and RCS are in excellent agreement with the benchmark data. It is concluded that with continuing advances in FD-TD modeling theory for target features relevant to the RCS problems and in vector and concurrent supercomputer technology, it is likely that FD-TD numerical modeling will occupy an important place in RCS technology in the 1990s and beyond.

Femtosecond pump-probe microscopy generates virtual cross-sections in historic artwork

PubMed Central

Villafana, Tana Elizabeth; Brown, William P.; Delaney, John K.; Palmer, Michael; Warren, Warren S.; Fischer, Martin C.

2014-01-01

The layering structure of a painting contains a wealth of information about the artist's choice of materials and working methods, but currently, no 3D noninvasive method exists to replace the taking of small paint samples in the study of the stratigraphy. Here, we adapt femtosecond pump-probe imaging, previously shown in tissue, to the case of the color palette in paintings, where chromophores have much greater variety. We show that combining the contrasts of multispectral and multidelay pump-probe spectroscopy permits nondestructive 3D imaging of paintings with molecular and structural contrast, even for pigments with linear absorption spectra that are broad and relatively featureless. We show virtual cross-sectioning capabilities in mockup paintings, with pigment separation and nondestructive imaging on an intact 14th century painting (The Crucifixion by Puccio Capanna). Our approach makes it possible to extract microscopic information for a broad range of applications to cultural heritage. PMID:24449855

Autoresonant Control of Elliptical Non-neutral Plasmas

NASA Astrophysics Data System (ADS)

Friedland, Lazar

1999-11-01

It is shown that placing a magnetized non-neutral plasma column in a weak oscillating transverse quadrupolar potential with chirped oscillation frequency allows excitation and control of the ellipticity and rotation phase of the plasma cross section. For a given chirp rate of the driving frequency, the phenomenon has a sharp threshold on the amplitude of the perturbing potential. The effect is analogous to that reported in controlling Kirchhoff vortices in fluid dynamics [1]. The ellipticity of the plasma cross section is manipulated by using autoresonance (nonlinear phase locking) in the system between the ExB drifting plasma particles and adiabatically varying driving potential. A similar idea was used recently in controlling the l=1 diocotron mode in a non-neutral plasma [2]. [1] L. Friedland, Phys. Rev. E59, 4106 (1999). [2] J. Fajans, E. Gilson, and L. Friedland, Phys. Rev. Lett. 82, 4444 (1999).

Study of the invariant structure function of the reaction. pi. /sup -/p. --> gamma. /sup +/xxx at 5 GeV/c

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

Amaglobeli, N.S.; Budagov, Y.A.; Valkar, S.

1977-07-01

The invariant differential cross section f (x,p/sub perpendicular/) of the reaction ..pi../sup -/p..--> gamma../sup +/xxx at 5 GeV/c was measured in a broad range of x and p/sub perpendicular/. An approximating formula is found for f (x,p/sub perpendicular/). It is shown that the function f (x,p/sub perpendicular/) is not factorizable in the variables x and p/sub perpendicular/. In some regions of phase space scale-invariant (scaling) behavior of the differential cross section is observed. Analysis of the asymmetry of the longitudinal momentum spectrum of the photons indicates that the production mechanisms of neutral and charged pions are similar in the centralmore » region. The results of the analysis are in qualitative agreement with the predictions of the quark model of hadrons.« less

Proton--H/sub 2/ scattering on an ab initio CI potential energy surface. II. Combined vibrational--rotational excitation at 4. 67 and 6 eV

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

Schinke, R.

1980-04-01

Infinite-order-sudden calculations have been performed at 4.67 and 6 eV on the ab initio CI potential energy surface determined recently by Schinke, Dupuis, and Lester. The vibrational degree of freedom has been treated exactly by solving vibrationally coupled radial equations. The rotationally summed differential cross sections for vibrational excitation are in good agreement with the measurements of Schmidt, Hermann, and Linder. It is shown that the rotational excitation cross sections in the vibrational ground state near the rainbow angle are almost exclusively determined by the potential between 2.5a/sub 0/ and 5a/sub 0/ proton--H/sub 2/ separations. In this region only themore » V/sub 2/ term of an expansion into Legendre polynomials is nonvanishing and is a factor of approx.3 smaller for the new surface than for the Giese and Gentry analytic potential. These differences result in a dramatic decrease of the rotational excitation cross sections in the rainbow region so that the present theoretical transition probabilities are in much better agreement with the experiments than our previous sudden vib--rotor calculations utilizing Giese and Gentry's surface.« less

The evaluation of Murray's law in Psilotum nudum (Psilotaceae), an analogue of ancestral vascular plants.

PubMed

McCulloh, Katherine A; Sperry, John S

2005-06-01

Previous work has shown that the xylem of seed plants follows Murray's law when conduits do not provide structural support to the plant. Here, compliance with Murray's law was tested in the stem photosynthesizer Psilotum nudum, a seedless vascular plant. Psilotum nudum was chosen because the central stele does not provide structural support, which means that Murray's law is applicable, and because its simple shoot structure resembles the earliest vascular plants. Murray's law predicts that the sum of the conduit radii cubed (Σr(3)) should decrease in direct proportion with the volume flow rate (Q) to maximize the hydraulic conductance per unit vascular investment. Agreement with Murray's law was assessed by estimating the transpiration rate distal to a cross-section, which should determine Q under steady state conditions, and comparing that with the Σr(3) of that cross-section. As predicted, regressions between the Σr(3) of the cross-section and Q resulted in a linear relationship with a y-intercept that was not different from zero. Two more rigorous statistical tests were also unable to reject Murray's law. Psilotum nudum plants also increased their conductance per investment by having more conduits distally than proximally, which is more efficient hydraulically than equal or declining conduit numbers distally.

Comparative study of the scalar- and tensor-meson production in the reaction γγ{sup *} (Q{sup 2})→ ηπ{sup 0}

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

Achasov, N. N., E-mail: achasov@math.nsc.ru; Kiselev, A. V., E-mail: kiselev@math.nsc.ru; Shestakov, G. N., E-mail: shestako@math.nsc.ru

2016-05-15

The cross section for the reaction γγ{sup *} (Q{sup 2})→ ηπ{sup 0} was predicted on the basis of a simultaneous analysis of data from the Belle detector (Japan) on the reaction γγ → ηπ{sup 0} and data the KLOE detector (Italy) on the decay process ϕ → ηπ{sup 0}γ. The production of a{sub 0}(980) scalar and a{sub 2}(1320) tensor mesons was studied in detail. It is shown that the QCD-predicted asymptotic behavior of the cross section for the process γ{sup *}(Q{sup 2})γ → a{sub 2}(1320) → ηπ{sup 0} can be reproduced only upon taking into account the compensation of themore » contributions of ρ(770) and ω(782) mesons in the leading order by the contributions of their radial excitations in the Q{sup 2} channel. It is expected that, at large Q{sup 2}, the cross section is dominated by the a{sub 2}(1320) contribution, but that, at Q{sup 2} = 0, the a{sub 2}(1320) contribution is commensurate with the scalarmeson contribution.« less

FY07 LDRD Final Report Neutron Capture Cross-Section Measurements at DANCE

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

Parker, W; Agvaanluvsan, U; Wilk, P

2008-02-08

We have measured neutron capture cross sections intended to address defense science problems including mix and the Quantification of Margins and Uncertainties (QMU), and provide details about statistical decay of excited nuclei. A major part of this project included developing the ability to produce radioactive targets. The cross-section measurements were made using the white neutron source at the Los Alamos Neutron Science Center, the detector array called DANCE (The Detector for Advanced Neutron Capture Experiments) and targets important for astrophysics and stockpile stewardship. DANCE is at the leading edge of neutron capture physics and represents a major leap forward inmore » capability. The detector array was recently built with LDRD money. Our measurements are a significant part of the early results from the new experimental DANCE facility. Neutron capture reactions are important for basic nuclear science, including astrophysics and the statistics of the {gamma}-ray cascades, and for applied science, including stockpile science and technology. We were most interested in neutron capture with neutron energies in the range between 1 eV and a few hundred keV, with targets important to basic science, and the s-process in particular. Of particular interest were neutron capture cross-section measurements of rare isotopes, especially radioactive isotopes. A strong collaboration between universities and Los Alamos due to the Academic Alliance was in place at the start of our project. Our project gave Livermore leverage in focusing on Livermore interests. The Lawrence Livermore Laboratory did not have a resident expert in cross-section measurements; this project allowed us to develop this expertise. For many radionuclides, the cross sections for destruction, especially (n,{gamma}), are not well known, and there is no adequate model that describes neutron capture. The modeling problem is significant because, at low energies where capture reactions are important, the neutron reaction cross sections show resonance behavior or follow 1/v of the incident neutrons. In the case of odd-odd nuclei, the modeling problem is particularly difficult because degenerate states (rotational bands) present in even-even nuclei have separated in energy. Our work included interpretation of the {gamma}-ray spectra to compare with the Statistical Model and provides information on level density and statistical decay. Neutron capture cross sections are of programmatic interest to defense sciences because many elements were added to nuclear devices in order to determine various details of the nuclear detonation, including fission yields, fusion yields, and mix. Both product nuclei created by (n,2n) reactions and reactant nuclei are transmuted by neutron capture during the explosion. Very few of the (n,{gamma}) cross sections for reactions that create products measured by radiochemists have ever been experimentally determined; most are calculated by radiochemical equivalences. Our new experimentally measured capture cross sections directly impact our knowledge about the uncertainties in device performances, which enhances our capability of carrying out our stockpile stewardship program. Europium and gadolinium cross sections are important for both astrophysics and defense programs. Measurements made prior to this project on stable europium targets differ by 30-40%, which was considered to be significantly disparate. Of the gadolinium isotopes, {sup 151}Gd is important for stockpile stewardship, and {sup 153}Gd is of high interest to astrophysics, and nether of these (radioactive) gadolinium (n,{gamma}) cross sections have been measured. Additional stable gadolinium isotopes, including {sup 157,160}Gd are of interest to astrophysics. Historical measurements of gadolinium isotopes, including {sup 152,154}Gd, had disagreements similar to the 30-40% disagreements found in the historical europium data. Actinide capture cross section measurements are important for both Stockpile Stewardship and for nuclear forensics. We focused on the {sup 242m}Am(n,{gamma}) measurement, as there was no existing capture measurement for this isotope. The cross-section measurements (cross section vs. E{sub n}) were made at the Detector for Advanced Neutron Capture Experiments. DANCE is comprised of a highly segmented array of barium fluoride (BaF{sub 2}) crystals specifically designed for neutron capture-gamma measurements, using small radioactive targets (less than one milligram). A picture of half the array, along with a photo of one crystal, is shown in Fig. 1. DANCE provides the world's leading capability for measurements of neutron capture cross sections with radioactive targets. The DANCE is a 4{pi} calorimeter and uses the intense spallation neutron source the Lujan Center at the Los Alamos National Laboratory. The detector array consists of 159 barium fluoride crystals arranged in a sphere around the target.« less

Electromagnetic properties of baryon resonances

NASA Astrophysics Data System (ADS)

Tiator, Lothar

2013-10-01

Longitudinal and transverse transition form factors for most of the four-star nucleon resonances have been obtained from high-quality cross section data and polarization observables measured at MAMI, ELSA, BATES, GRAAL and CEBAF. As an application, we further show how the transition form factors can be used to obtain empirical transverse charge densities. Contour plots of the thus derived densities are shown and compared for the Roper and S11 nucleon resonances.

Silicon technology-based micro-systems for atomic force microscopy/photon scanning tunnelling microscopy.

PubMed

Gall-Borrut, P; Belier, B; Falgayrettes, P; Castagne, M; Bergaud, C; Temple-Boyer, P

2001-04-01

We developed silicon nitride cantilevers integrating a probe tip and a wave guide that is prolonged on the silicon holder with one or two guides. A micro-system is bonded to a photodetector. The resulting hybrid system enables us to obtain simultaneously topographic and optical near-field images. Examples of images obtained on a longitudinal cross-section of an optical fibre are shown.

Numerical Simulation of Ultra-Fast Pulse Propagation in Two-Photon Absorbing Medium

DTIC Science & Technology

2011-08-01

physical problems including coherent- and incoherent regimes of optical power limiting, saturation, CEP effects, soliton formation etc. It can be also...coherent- and incoherent regimes of optical power limiting, saturation, CEP effects, electromagnetically induced transparency, soliton formation etc...experimental data ( dark blue); Upper panel - 1PA spectrum; Lower panel - 2PA cross section spectrum. The parameter values used are shown in Table 1. 10

Relationships between Electrical and Radar Characteristics of Thunderstorms Observed During ACES

NASA Technical Reports Server (NTRS)

Buechler, Dennis E.; Mach, Douglas M.; Blakeslee, Richard J.

2003-01-01

The Altus Cumulus Electrification Study (ACES) took place near Key West, Florida during August 2002. A high altitude, remotely piloted aircraft obtained optical pulse and electric field data over a number of thunderstorms during the study period. Measurements of the vertical electric field and cross sections of radar reflectivity along the flight track are shown for 2 overpasses of a thunderstorm that occurred on 10 August 2002.

A Proposal for a Dimensional Classification System Based on the Shared Features of the "DSM-IV" Anxiety and Mood Disorders: Implications for Assessment and Treatment

ERIC Educational Resources Information Center

Brown, Timothy A.; Barlow, David H.

2009-01-01

A wealth of evidence attests to the extensive current and lifetime diagnostic comorbidity of the "Diagnostic and Statistical Manual of Mental Disorders" (4th ed., "DSM-IV") anxiety and mood disorders. Research has shown that the considerable cross-sectional covariation of "DSM-IV" emotional disorders is accounted for by common higher order…

Pseudoscalar Meson Electroproduction and Transversity

NASA Astrophysics Data System (ADS)

Goldstein, Gary R.; Liuti, Simonetta

2011-02-01

Exclusive meson leptoproduction from nucleons in the deeply virtual exchanged boson limit can be described by generalized parton distributions (GPDs). Including spin dependence in the description requires 8 independent quark-parton and gluon-parton functions. The chiral even subset of 4 quark-nucleon GPDs are related to nucleon form factors and to parton distribution functions. The chiral odd set of 4 quark-nucleon GPDs are related to transversity, the tensor charge, and other quantities related to transversity. Different meson or photon production processes access different combinations of GPDs. This is analyzed in terms of t-channel exchange quantum numbers, JPC and it is shown that pseudoscalar production can isolate chiral odd GPDs. There is a sensitive dependence in various cross sections and asymmetries on the tensor charge of the nucleon and other transversity parameters. In a second section, analyticity and completeness are shown to limit the partonic interpret ation of the GPDs in the ERBL region.

Modeling and design of optimal flow perfusion bioreactors for tissue engineering applications.

PubMed

Hidalgo-Bastida, L Araida; Thirunavukkarasu, Sundaramoorthy; Griffiths, Sarah; Cartmell, Sarah H; Naire, Shailesh

2012-04-01

Perfusion bioreactors have been used in different tissue engineering applications because of their consistent distribution of nutrients and flow-induced shear stress within the tissue-engineering scaffold. A widely used configuration uses a scaffold with a circular cross-section enclosed within a cylindrical chamber and inlet and outlet pipes which are connected to the chamber on either side through which media is continuously circulated. However, fluid-flow experiments and simulations have shown that the majority of the flow perfuses through the center. This pattern creates stagnant zones in the peripheral regions as well as in those of high flow rate near the inlet and outlet. This non-uniformity of flow and shear stress, owing to a circular design, results in limited cell proliferation and differentiation in these areas. The focus of this communication is to design an optimized perfusion system using computational fluid dynamics as a mathematical tool to overcome the time-consuming trial and error experimental method. We compared the flow within a circular and a rectangular bioreactor system. Flow simulations within the rectangular bioreactor are shown to overcome the limitations in the circular design. This communication challenges the circular cross-section bioreactor configuration paradigm and provides proof of the advantages of the new design over the existing one. Copyright © 2011 Wiley Periodicals, Inc.

Production of bare argon, manganese, iron and nickel nuclei in the Dresden EBIT

NASA Astrophysics Data System (ADS)

Kentsch, U.; Zschornack, G.; Großmann, F.; Ovsyannikov, V. P.; Ullmann, F.; Fritzsche, S.; Surzhykov, A.

2002-02-01

The production of highly charged argon, manganese, iron and nickel ions in a room-temperature electron beam ion trap (EBIT), the Dresden EBIT, has been investigated by means of energy dispersive X-ray spectroscopy of the direct excitation (DE) and radiative recombination (RR) processes. To derive the charge state distributions of the ions in the trap, direct excitation and radiative recombination cross-sections were calculated at electron energies of 8 and 14.4 keV. Based on these theoretical cross-sections and the measured X-ray spectra, the ion densities and the absolute number of ions, which are trapped in the electron beam, are determined for argon, manganese, iron and nickel. Emphasis has been paid to the highly charged ions, including the helium-like and hydrogen-like ions and bare nuclei. In the case of iron we also determined the contributions from lower ionization stages from DE transition lines. It is shown, that in the Dresden EBIT elements at least up to nickel can be fully ionized. Beside energy dispersive spectroscopy it is shown for iron by wavelength dispersive X-ray spectroscopy that with a comparably high gas pressure in the order of 10 -8 mbar carbon-, boron-, beryllium-, lithium- and helium-like iron ions can be produced.

Comparative studies of mucilage cells in different organs in some species of Malva, Althaea and Alcea.

PubMed

Pakravan, M; Abedinzadeh, H; Safaeepur, J

2007-08-01

Distribution of Mucilage Cells (MC) in leaves and petals of two species of Malva L. : Malva neglecta Wallr and M. nicaeensis All, one species of Altheae L.: A. officinalis L. and one species of Alcea L: A. angulata (Freyn and Sint.) Freyn and Sint. ex Iljin, have studied. Except ofA. angulata that mucilage cells observed both in epidermis and mesophyll of leaves, in the others mucilage cells confined to epidermis cells. All of species have mucilage cells in the petals. The area of the mucilaginous elements in the leaves and petals of species determined planimetrically on definite cross-sections was studied as a comparative element to the mucilage content determined by extracting the raw mucilage by Hot Extraction Method (HEM) and then by comparing the dry weight, comparison between species was done. A correlation between the greater area of the mucilaginous elements and the mucilage content measured by methods mentioned was shown, basing on different microscopic examination of cross-sections of the organs fixed and stained with ruthenium red. The results were shown that mucilage content in the leaves of Malva neglecta was more than the others and mucilage content in petals of Malva neglecta was more than the others.

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

Monaghan, P; Shneor, R; Subedi, R

The five-fold differential cross section for the 12C(e,e'p)11B reaction was determined over a missing momentum range of 200-400 MeV/c, in a kinematics regime with Bjorken x > 1 and Q2 = 2.0 (GeV/c)2. A comparison of the results and theoretical models and previous lower missing momentum data is shown. The theoretical calculations agree well with the data up to a missing momentum value of 325 MeV/c and then diverge for larger missing momenta. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV/c.

Analysis of 2-spar cantilever wings with special reference to torsion and load transference

NASA Technical Reports Server (NTRS)

Kuhn, Paul

1936-01-01

This report deals with the analysis of 2-spar cantilever wings in torsion, taking cognizance of the fact that the spars are not independent, but are interconnected by ribs and other structural members. The principles of interaction are briefly explained, showing that the mutual relief action occurring depends on the "pure torsional stiffness" of the wing cross section. Various practical methods of analysis are outlined. The "Friedrichs-Von Karman equations" are shown to require the least amount of labor. Numerical examples by the several methods of analysis are given and the agreement between the calculation and experiment is shown.

Temporal Effects on Internal Fluorescence Emissions Associated with Aflatoxin Contamination from Corn Kernel Cross-Sections Inoculated with Toxigenic and Atoxigenic Aspergillus flavus.

PubMed

Hruska, Zuzana; Yao, Haibo; Kincaid, Russell; Brown, Robert L; Bhatnagar, Deepak; Cleveland, Thomas E

2017-01-01

Non-invasive, easy to use and cost-effective technology offers a valuable alternative for rapid detection of carcinogenic fungal metabolites, namely aflatoxins, in commodities. One relatively recent development in this area is the use of spectral technology. Fluorescence hyperspectral imaging, in particular, offers a potential rapid and non-invasive method for detecting the presence of aflatoxins in maize infected with the toxigenic fungus Aspergillus flavus . Earlier studies have shown that whole maize kernels contaminated with aflatoxins exhibit different spectral signatures from uncontaminated kernels based on the external fluorescence emission of the whole kernels. Here, the effect of time on the internal fluorescence spectral emissions from cross-sections of kernels infected with toxigenic and atoxigenic A. flavus , were examined in order to elucidate the interaction between the fluorescence signals emitted by some aflatoxin contaminated maize kernels and the fungal invasion resulting in the production of aflatoxins. First, the difference in internal fluorescence emissions between cross-sections of kernels incubated in toxigenic and atoxigenic inoculum was assessed. Kernels were inoculated with each strain for 5, 7, and 9 days before cross-sectioning and imaging. There were 270 kernels (540 halves) imaged, including controls. Second, in a different set of kernels (15 kernels/group; 135 total), the germ of each kernel was separated from the endosperm to determine the major areas of aflatoxin accumulation and progression over nine growth days. Kernels were inoculated with toxigenic and atoxigenic fungal strains for 5, 7, and 9 days before the endosperm and germ were separated, followed by fluorescence hyperspectral imaging and chemical aflatoxin determination. A marked difference in fluorescence intensity was shown between the toxigenic and atoxigenic strains on day nine post-inoculation, which may be a useful indicator of the location of aflatoxin contamination. This finding suggests that both, the fluorescence peak shift and intensity as well as timing, may be essential in distinguishing toxigenic and atoxigenic fungi based on spectral features. Results also reveal a possible preferential difference in the internal colonization of maize kernels between the toxigenic and atoxigenic strains of A. flavus suggesting a potential window for differentiating the strains based on fluorescence spectra at specific time points.

Temporal Effects on Internal Fluorescence Emissions Associated with Aflatoxin Contamination from Corn Kernel Cross-Sections Inoculated with Toxigenic and Atoxigenic Aspergillus flavus

PubMed Central

Hruska, Zuzana; Yao, Haibo; Kincaid, Russell; Brown, Robert L.; Bhatnagar, Deepak; Cleveland, Thomas E.

2017-01-01

Non-invasive, easy to use and cost-effective technology offers a valuable alternative for rapid detection of carcinogenic fungal metabolites, namely aflatoxins, in commodities. One relatively recent development in this area is the use of spectral technology. Fluorescence hyperspectral imaging, in particular, offers a potential rapid and non-invasive method for detecting the presence of aflatoxins in maize infected with the toxigenic fungus Aspergillus flavus. Earlier studies have shown that whole maize kernels contaminated with aflatoxins exhibit different spectral signatures from uncontaminated kernels based on the external fluorescence emission of the whole kernels. Here, the effect of time on the internal fluorescence spectral emissions from cross-sections of kernels infected with toxigenic and atoxigenic A. flavus, were examined in order to elucidate the interaction between the fluorescence signals emitted by some aflatoxin contaminated maize kernels and the fungal invasion resulting in the production of aflatoxins. First, the difference in internal fluorescence emissions between cross-sections of kernels incubated in toxigenic and atoxigenic inoculum was assessed. Kernels were inoculated with each strain for 5, 7, and 9 days before cross-sectioning and imaging. There were 270 kernels (540 halves) imaged, including controls. Second, in a different set of kernels (15 kernels/group; 135 total), the germ of each kernel was separated from the endosperm to determine the major areas of aflatoxin accumulation and progression over nine growth days. Kernels were inoculated with toxigenic and atoxigenic fungal strains for 5, 7, and 9 days before the endosperm and germ were separated, followed by fluorescence hyperspectral imaging and chemical aflatoxin determination. A marked difference in fluorescence intensity was shown between the toxigenic and atoxigenic strains on day nine post-inoculation, which may be a useful indicator of the location of aflatoxin contamination. This finding suggests that both, the fluorescence peak shift and intensity as well as timing, may be essential in distinguishing toxigenic and atoxigenic fungi based on spectral features. Results also reveal a possible preferential difference in the internal colonization of maize kernels between the toxigenic and atoxigenic strains of A. flavus suggesting a potential window for differentiating the strains based on fluorescence spectra at specific time points. PMID:28966606

Lateral and posterior dynamic bending of the mid-shaft femur: fracture risk curves for the adult population.

PubMed

Kennedy, Eric A; Hurst, William J; Stitzel, Joel D; Cormier, Joseph M; Hansen, Gail A; Smith, Eric P; Duma, Stefan M

2004-11-01

The purpose of this study was to develop injury risk functions for dynamic bending of the human femur in the lateral-to-medial and posterior-to-anterior loading directions. A total of 45 experiments were performed on human cadaver femurs using a dynamic three-point drop test setup. An impactor of 9.8 kg was dropped from 2.2 m for an impact velocity of 5 m/s. Five-axis load cells measured the impactor and support loads, while an in situ strain gage measured the failure strain and subsequent strain rate. All 45 tests resulted in mid-shaft femur fractures with comminuted wedge and oblique fractures as the most common fracture patterns. In the lateral-to-medial bending tests the reaction loads were 4180 +/- 764 N, and the impactor loads were 4780 +/- 792 N. In the posterior-to-anterior bending tests the reaction loads were 3780 +/- 930 N, and the impactor loads were 4310 +/- 1040 N. The difference between the sum of the reaction forces and the applied load is due to inertial effects. The reaction loads were used to estimate the mid-shaft bending moments at failure since there was insufficient data to include the inertial effects in the calculations. The resulting moments are conservative estimates (lower bounds) of the mid-shaft bending moments at failure and are appropriate for use in the assessment of knee restraints and pedestrian impacts with ATD measurements. Regression analysis was used to identify significant parameters, and parametric survival analysis was used to estimate risk functions. Femur cross-sectional area, area moment of inertia (I), maximum distance to the neutral axis (c), I/c, occupant gender, and occupant mass are shown to be significant predictors of fracture tolerance, while no significant difference is shown for loading direction, bone mineral density, leg aspect and age. Risk functions are presented for femur cross-sectional area and I/c as they offer the highest correlation to peak bending moment. The risk function that utilizes the most highly correlated (R2 = 0.82) and significant (p = 0.0001) variable, cross-sectional area, predicts a 50 percent risk of femur fracture of 240 Nm, 395 Nm, and 562 Nm for equivalent cross-sectional area of the 5(th) percentile female, 50(th) percentile male, and 95(th) percentile male respectively.

Discovery of previously unrecognised local faults in London, UK, using detailed 3D geological modelling

NASA Astrophysics Data System (ADS)

Aldiss, Don; Haslam, Richard

2013-04-01

In parts of London, faulting introduces lateral heterogeneity to the local ground conditions, especially where construction works intercept the Palaeogene Lambeth Group. This brings difficulties to the compilation of a ground model that is fully consistent with the ground investigation data, and so to the design and construction of engineering works. However, because bedrock in the London area is rather uniform at outcrop, and is widely covered by Quaternary deposits, few faults are shown on the geological maps of the area. This paper discusses a successful resolution of this problem at a site in east central London, where tunnels for a new underground railway station are planned. A 3D geological model was used to provide an understanding of the local geological structure, in faulted Lambeth Group strata, that had not been possible by other commonly-used methods. This model includes seven previously unrecognised faults, with downthrows ranging from about 1 m to about 12 m. The model was constructed in the GSI3D geological modelling software using about 145 borehole records, including many legacy records, in an area of 850 m by 500 m. The basis of a GSI3D 3D geological model is a network of 2D cross-sections drawn by a geologist, generally connecting borehole positions (where the borehole records define the level of the geological units that are present), and outcrop and subcrop lines for those units (where shown by a geological map). When the lines tracing the base of each geological unit within the intersecting cross-sections are complete and mutually consistent, the software is used to generate TIN surfaces between those lines, so creating a 3D geological model. Even where a geological model is constructed as if no faults were present, changes in apparent dip between two data points within a single cross-section can indicate that a fault is present in that segment of the cross-section. If displacements of similar size with the same polarity are found in a series of adjacent cross-sections, the presence of a fault can be substantiated. If it is assumed that the fault is planar and vertical, then the pairs of constraining data points in each cross-section form a two-dimensional envelope within which the surface trace of the fault must lie. Generally, the broader the area of the model, the longer the envelope defined by the pairs of boreholes is, resulting in better constraint of the fault zone width and azimuth. Repetition or omission of the local stratigraphy in the constraining boreholes can demonstrate reverse or normal dip-slip motion. Even if this is not possible, borehole intercepts at the base of the youngest bedrock unit or at the top of the oldest bedrock unit can constrain the minimum angle of dip of the fault plane. Assessment of the maximum angle of dip requires intrusive investigation. This work is distributed under the Creative Commons Attribution 3.0 Unported License together with an NERC copyright. This license does not conflict with the regulations of the Crown Copyright.

Predicting strain using forward modelling of restored cross-sections: Application to rollover anticlines over listric normal faults

NASA Astrophysics Data System (ADS)

Poblet, Josep; Bulnes, Mayte

2007-12-01

A strategy to predict strain across geological structures, based on previous techniques, is modified and evaluated, and a practical application is shown. The technique, which employs cross-section restoration combined with kinematic forward modelling, consists of restoring a section, placing circular strain markers on different domains of the restoration, and forward modelling the restored section with strain markers until the present-day stage is reached. The restoration algorithm employed must be also used to forward model the structure. The ellipses in the forward modelled section allow determining the strain state of the structure and may indirectly predict orientation and distribution of minor structures such as small-scale fractures. The forward model may be frozen at different time steps (different growth stages) allowing prediction of both spatial and temporal variation of strain. The method is evaluated through its application to two stages of a clay experiment, that includes strain markers, and its geometry and deformation history are well documented, providing a strong control on the results. To demonstrate the method's potential, it is successfully applied to a depth-converted seismic profile in the Central Sumatra Basin, Indonesia. This allowed us to gain insight into the deformation undergone by rollover anticlines over listric normal faults.

Dietary Patterns, Cognitive Decline, and Dementia: A Systematic Review12

PubMed Central

van de Rest, Ondine; Berendsen, Agnes AM; Haveman-Nies, Annemien; de Groot, Lisette CPGM

2015-01-01

Nutrition is an important modifiable risk factor that plays a role in the strategy to prevent or delay the onset of dementia. Research on nutritional effects has until now mainly focused on the role of individual nutrients and bioactive components. However, the evidence for combined effects, such as multinutrient approaches, or a healthy dietary pattern, such as the Mediterranean diet, is growing. These approaches incorporate the complexity of the diet and possible interaction and synergy between nutrients. Over the past few years, dietary patterns have increasingly been investigated to better understand the link between diet, cognitive decline, and dementia. In this systematic review we provide an overview of the literature on human studies up to May 2014 that examined the role of dietary patterns (derived both a priori as well as a posteriori) in relation to cognitive decline or dementia. The results suggest that better adherence to a Mediterranean diet is associated with less cognitive decline, dementia, or Alzheimer disease, as shown by 4 of 6 cross-sectional studies, 6 of 12 longitudinal studies, 1 trial, and 3 meta-analyses. Other healthy dietary patterns, derived both a priori (e.g., Healthy Diet Indicator, Healthy Eating Index, and Program National Nutrition Santé guideline score) and a posteriori (e.g., factor analysis, cluster analysis, and reduced rank regression), were shown to be associated with reduced cognitive decline and/or a reduced risk of dementia as shown by all 6 cross-sectional studies and 6 of 8 longitudinal studies. More conclusive evidence is needed to reach more targeted and detailed guidelines to prevent or postpone cognitive decline. PMID:25770254

Geologic map of the Shaida deposit and Misgaran prospect, Herat Province, Afghanistan, modified from the 1973 original map compilation of V.I. Tarasenko and others

USGS Publications Warehouse

Tucker, Robert D.; Stettner, Will R.; Masonic, Linda M.; Moran, Thomas W.

2014-01-01

This map is a modified version of Geological map and map of useful minerals, Shaida area, scale 1:50,000, which was compiled by V.I. Tarasenko, N.I. Borozenets, and others in 1973. Scientists from the U.S. Geological Survey, in cooperation with the Afghan Geological Survey and the Task Force for Business and Stability Operations of the U.S. Department of Defense, studied the original document and related reports and also visited the field area in August 2010.This modified map illustrates the geological structure of the Shaida copper-lead-zinc deposit and Misgaran copper-lead-zinc prospect in western Afghanistan and includes cross sections of the same area. The map reproduces the topology (contacts, faults, and so forth) of the original Soviet map and cross sections and includes modifications based on our examination of these documents and on observations made during our field visit. Elevations on the cross sections are derived from the original Soviet topography and might not match the newer topography used on the current map. We have attempted to translate the original Russian terminology and rock classification into modern English geologic usage as literally as possible without changing any genetic or process-oriented implications in the original descriptions. We also use the age designations from the original map.The unit colors on the map and cross sections differ from the colors shown on the original version. The units are colored according to the color and pattern scheme of the Commission for the Geological Map of the World (CGMW) (http://www.ccgm.org).

Short-Term effects of neuromuscular electrical stimulation on muscle architecture of the tibialis anterior and gastrocnemius in children with cerebral palsy: preliminary results of a prospective controlled study.

PubMed

Karabay, İlkay; Öztürk, Gökhan Tuna; Malas, Fevziye Ünsal; Kara, Murat; Tiftik, Tülay; Ersöz, Murat; Özçakar, Levent

2015-09-01

The aim of this study was to explore the short-term effects of neuromuscular electrical stimulation application on tibialis anterior (stimulated muscle) and gastrocnemius (antagonist) muscles' size and architecture in children with cerebral palsy by using ultrasound. This prospective, controlled study included 28 children diagnosed with spastic diplegic cerebral palsy. Participants were treated either with neuromuscular electrical stimulation application and conventional physiotherapy (group A) or with conventional physiotherapy alone (group B). Outcome was evaluated by clinical (gross motor function, selective motor control, range of motion, spasticity) and ultrasonographic (cross-sectional area, pennation angle, fascicle length of tibialis anterior and gastrocnemius muscles) measurements before and after treatment in both groups. Cross-sectional area values of tibialis anterior (238.7 ± 61.5 vs. 282.0 ± 67.1 mm) and gastrocnemius (207.9 ± 48.0 vs. 229.5 ± 52.4 mm) (P < 0.001 and P = 0.008, respectively) muscles were increased after treatment in group A. Cross-sectional area values of tibialis anterior muscle were decreased (257.3 ± 64.7 vs. 239.7 ± 60.0 mm) after treatment in group B (P < 0.001), and the rest of the measurements were found not to have changed significantly in either group. These results have shown that cross-sectional area of both the agonist and antagonist muscles increased after 20 sessions of neuromuscular electrical stimulation treatment. Future studies with larger samples and longer follow-up are definitely awaited for better evaluation of neuromuscular electrical stimulation application on muscle architecture and its possible correlates in clinical/functional outcome.

A spectral-Tchebychev solution for three-dimensional dynamics of curved beams under mixed boundary conditions

NASA Astrophysics Data System (ADS)

Bediz, Bekir; Aksoy, Serdar

2018-01-01

This paper presents the application of the spectral-Tchebychev (ST) technique for solution of three-dimensional dynamics of curved beams/structures having variable and arbitrary cross-section under mixed boundary conditions. To accurately capture the vibrational behavior of curved structures, a three-dimensional (3D) solution approach is required since these structures generally exhibit coupled motions. In this study, the integral boundary value problem (IBVP) governing the dynamics of the curved structures is found using extended Hamilton's principle where the strain energy is expressed using 3D linear elasticity equation. To solve the IBVP numerically, the 3D spectral Tchebychev (3D-ST) approach is used. To evaluate the integral and derivative operations defined by the IBVP and to render the complex geometry into an equivalent straight beam with rectangular cross-section, a series of coordinate transformations are applied. To validate and assess the performance of the presented solution approach, two case studies are performed: (i) curved beam with rectangular cross-section, (ii) curved and pretwisted beam with airfoil cross-section. In both cases, the results (natural frequencies and mode shapes) are also found using a finite element (FE) solution approach. It is shown that the difference in predicted natural frequencies are less than 1%, and the mode shapes are in excellent agreement based on the modal assurance criteria (MAC) analyses; however, the presented spectral-Tchebychev solution approach significantly reduces the computational burden. Therefore, it can be concluded that the presented solution approach can capture the 3D vibrational behavior of curved beams as accurately as an FE solution, but for a fraction of the computational cost.

General stability of composite panels reinforced with flexible rods taking account of the side boundary conditions

NASA Astrophysics Data System (ADS)

Dudchenko, A. A.; Elpat'evskii, A. N.

1995-07-01

Reinforced panels are the basic load-bearing elements of various structures. Optimization of massive structures requires consideration of deformation of the panel cross-sections. This is particularly important in determining the bearing strength at buckling. The load scheme, conditions for fixation of the panel cross-section, and bend-torsional stiffness taking account of the deformation of the rod cross-section affect the buckling load in real structures. The stress distribution prior to buckling must be known to solve the buckling problem properly. The stress in the panel is proportional to the active load. The stress distribution is assumed to be known according to our previous method [1]. The load scheme and panel dimensions are shown in Fig. 1. The stress distribution in the panel prior to buckling can be found using Eqs. (1)-(3). A view of the cross-section is given in Fig. 1. The displacements in the panel at buckling for the boundary area are found using Eqs. (4)-(6), while the stresses in the skin and stiffness are found using Eq. (7). Roots k1 and k2 are those of the characteristic equation and β is a dimensionless coordinate. The problem was solved using variational theory. The potential energy is given by Eqs. (8) and (9) by orihogonalization of Eqs. (5). The basic equations are converted to Eqs. (10) by evaluation of the components in Eqs. (8) and (9). Its calculation (11) gives the compression load. Optimization of parameter α gives the critical strength P1 = 6.93 kN (without taking account of the boundary area) and P2 = 5.31 kN (taking account of the boundary area).

Recent Efforts in Data Compilations for Nuclear Astrophysics

NASA Astrophysics Data System (ADS)

Dillmann, Iris

2008-05-01

Some recent efforts in compiling data for astrophysical purposes are introduced, which were discussed during a JINA-CARINA Collaboration meeting on ``Nuclear Physics Data Compilation for Nucleosynthesis Modeling'' held at the ECT* in Trento/Italy from May 29th-June 3rd, 2007. The main goal of this collaboration is to develop an updated and unified nuclear reaction database for modeling a wide variety of stellar nucleosynthesis scenarios. Presently a large number of different reaction libraries (REACLIB) are used by the astrophysics community. The ``JINA Reaclib Database'' on http://www.nscl.msu.edu/~nero/db/ aims to merge and fit the latest experimental stellar cross sections and reaction rate data of various compilations, e.g. NACRE and its extension for Big Bang nucleosynthesis, Caughlan and Fowler, Iliadis et al., and KADoNiS. The KADoNiS (Karlsruhe Astrophysical Database of Nucleosynthesis in Stars, http://nuclear-astrophysics.fzk.de/kadonis) project is an online database for neutron capture cross sections relevant to the s process. The present version v0.2 is already included in a REACLIB file from Basel university (http://download.nucastro.org/astro/reaclib). The present status of experimental stellar (n,γ) cross sections in KADoNiS is shown. It contains recommended cross sections for 355 isotopes between 1H and 210Bi, over 80% of them deduced from experimental data. A ``high priority list'' for measurements and evaluations for light charged-particle reactions set up by the JINA-CARINA collaboration is presented. The central web access point to submit and evaluate new data is provided by the Oak Ridge group via the http://www.nucastrodata.org homepage. ``Workflow tools'' aim to make the evaluation process transparent and allow users to follow the progress.

Metal poisons for criticality in waste streams

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

Williamson, T.G.; Goslen, A.Q.

1996-12-31

Many of the wastes from processing fissile materials contain metals that may serve as neutron poisons. It would be advantageous to the criticality evaluation of these wastes to demonstrate that the poisons remain with the fissile materials and to demonstrate an always safe poison-to-fissile ratio. The first task, demonstrating that the materials stay together, is the job of the chemist; the second, calculating an always safe ratio, is an object of this paper. In an earlier study, the authors demonstrated safe ratios for iron, manganese, and chromium oxides to {sup 235}U. In these studies, the Hansen-Roach 16-group cross sections weremore » used with the Savannah River site code HRXN. Multiplication factors were computed, and safe ratios were defined such that the adjusted neutron multiplication factors (k values) were <0.95. These safe weight ratios were Fe:{sup 235}U - 77:1; Mn:{sup 235}U - 30:1; and Cr:{sup 235}U - 52:1. Palmer has shown that for certain mixtures of aluminum, iron, and zirconium with {sup 235}U, the computed infinite multiplication factors may differ by as much as 20% with different cross sections and processing systems. Parks et al. have further studied these mixtures and state, {open_quotes}...these metal/uranium mixtures are very sensitive to the metal cross-section data in the intermediate-energy range and the processing methods that are used.{close_quotes} They conclude with a call for more experimental data. The purpose of this study is to reexamine earlier work with cross sections and processing codes used at Westinghouse Savannah River Company today. This study will focus on {sup 235}U mixtures with iron, manganese and chromium. Sodium will be included in the list of poisons because it is abundant in many of the waste materials.« less

Two-Way Pattern Design for Distributed Subarray Antennas

DTIC Science & Technology

2012-09-01

GUI Graphical User Interface HPBW Half-power Beamwidth MFR Multifunction Radar RCS Radar Cross Section RRE Radar Range Equation...The Aegis ships in the US Navy use phased arrays for the AN/SPY-1 multifunction radar ( MFR ) [2]. The phased array for the AN/SPY-1 radar is shown in...arrays. This is a challenge for design of antenna apertures for shipboard radar systems. One design approach is to use multi-function subarray

Heat Treatment Investigation of 4330 Vanadium-Modified Steel

DTIC Science & Technology

1989-08-01

the desired properties, using the results from the tensile and subsized Charpy impact tests on the 1 2-inch-diameter stock our further investigations...for the subsized Charpy specimens is shown graphically in Appendix C as a function of tempering temperature. This data gave a good indication that the... Charpy energy for full-sized specimens (0.394-inch-square cross section) would be near our expected values. Due to the dimensions of the subsized

Light scattering by cylindrical nanoparticles: Limits of applicability of the Rayleigh-Gans-Debye approximation

NASA Astrophysics Data System (ADS)

Kanevskii, V. I.; Rozenbaum, V. M.

2014-08-01

Applicability of the Rayleigh-Gans-Debye (RGD) approximation for describing light scattering by nanoparticles with large dielectric losses (such as carbon nanotubes) is analyzed. By a comparison of the approximate results with exact ones, it is shown that the presence of dielectric losses expands the range of applicability of the RGD approximation. This conclusion is illustrated by a differential cross-section diagram of scattering by a multiwall carbon nanotube.

The Other-Race Effect in a Longitudinal Sample of 3-, 6- and 9-Month-Old Infants: Evidence of a Training Effect

ERIC Educational Resources Information Center

Spangler, Sibylle M.; Schwarzer, Gudrun; Freitag, Claudia; Vierhaus, Marc; Teubert, Manuel; Fassbender, Ina; Lohaus, Arnold; Kolling, Thorsten; Graf, Frauke; Goertz, Claudia; Knopf, Monika; Lamm, Bettina; Keller, Heidi

2013-01-01

We investigated the development of the other-race effect "ORE" in a longitudinal sample of 3-, 6-, and 9-month-old Caucasian infants. Previous research using cross-sectional samples has shown an unstable ORE at 3 months, an increase at 6 months and full development at 9 months. In Experiment 1, we tested whether 9-month-olds showed the…

Well bore breakouts and in situ stress

USGS Publications Warehouse

Zoback, Mark D.; Moos, Daniel; Mastin, Larry; Anderson, Roger N.

1985-01-01

The detailed cross-sectional shape of stress induced well bore breakouts has been studied using specially processed ultrasonic borehole televiewer data. Breakout shapes are shown for a variety of rock types and introduce a simple elastic failure model which explains many features of the observations. Both the observations and calculations indicate that the breakouts define relatively broad and flat curvilinear surfaces which enlarge the borehole in the direction of minimum horizontal compression. Refs.

Interaction potentials and transport properties of Ba, Ba+, and Ba2+ in rare gases from He to Xe

NASA Astrophysics Data System (ADS)

Buchachenko, Alexei A.; Viehland, Larry A.

2018-04-01

A highly accurate, consistent set of ab initio interaction potentials is obtained for the title systems at the coupled cluster with singles, doubles, and non-iterative triples level of theory with extrapolation to the complete basis set limit. These potentials are shown to be more reliable than the previous potentials based on their long-range behavior, equilibrium properties, collision cross sections, and transport properties.

Calibration of polarimetric radar systems with good polarization isolation

NASA Technical Reports Server (NTRS)

Sarabandi, Kamal; Ulaby, Fawwaz T.; Tassoudji, M. Ali

1990-01-01

A practical technique is proposed for calibrating single-antenna polarimetric radar systems using a metal sphere plus any second target with a strong cross-polarized radar cross section. This technique assumes perfect isolation between antenna ports. It is shown that all magnitudes and phases (relative to one of the like-polarized linear polarization configurations) of the radar transfer function can be calibrated without knowledge of the scattering matrix of the second target. Comparison of the values measured (using this calibration technique) for a tilted cylinder at X-band with theoretical values shows agreement within + or - 0.3 dB in magnitude and + or - 5 degrees in phase. The radar overall cross-polarization isolation was 25 dB. The technique is particularly useful for calibrating a radar under field conditions, because it does not require the careful alignment of calibration targets.

Evaluation of Data Used for Modelling the Stratosphere of Saturn

NASA Astrophysics Data System (ADS)

Armstrong, Eleanor Sophie; Irwin, Patrick G. J.; Moses, Julianne I.

2015-11-01

Planetary atmospheres are modeled through the use of a photochemical and kinetic reaction scheme constructed from experimentally and theoretically determined rate coefficients, photoabsorption cross sections and branching ratios for the molecules described within them. The KINETICS architecture has previously been developed to model planetary atmospheres and is applied here to Saturn’s stratosphere. We consider the pathways that comprise the reaction scheme of a current model, and update the reaction scheme according the to findings in a literature investigation. We evaluate contemporary photochemical literature, studying recent data sets of cross-sections and branching ratios for a number of hydrocarbons used in the photochemical scheme of Model C of KINETICS. In particular evaluation of new photodissociation branching ratios for CH4, C2H2, C2H4, C3H3, C3H5 and C4H2, and new cross-sectional data for C2H2, C2H4, C2H6, C3H3, C4H2, C6H2 and C8H2 are considered. By evaluating the techniques used and data sets obtained, a new reaction scheme selection was drawn up. These data are then used within the preferred reaction scheme of the thesis and applied to the KINETICS atmospheric model to produce a model of the stratosphere of Saturn in a steady state. A total output of the preferred reaction scheme is presented, and the data is compared both with the previous reaction scheme and with data from the Cassini spacecraft in orbit around Saturn.One of the key findings of this work is that there is significant change in the model’s output as a result of temperature dependent data determination. Although only shown within the changes to the photochemical portion of the preferred reaction scheme, it is suggested that an equally important temperature dependence will be exhibited in the kinetic section of the reaction scheme. The photochemical model output is shown to be highly dependent on the preferred reaction scheme used within it by this thesis. The importance of correct and temperature-appropriate photochemical and kinetic data for the atmosphere under examination is emphasised as a consequence.

Photoeffect cross sections of some rare-earth elements at 145.4 keV

NASA Astrophysics Data System (ADS)

Umesh, T. K.; Ranganathaiah, C.; Sanjeevaiah, B.

1985-08-01

Total attenuation cross sections in the elements La, Ce, Pr, Nd, Sm, Gd, Dy, Ho, and Er were derived from the measured total cross sections of their simple oxide compounds, by employing the mixture rule at 145.4-keV photon energy. The compound cross sections have been measured by performing transmission experiments in a good geometry setup. From the derived total cross sections of elements, photoeffect cross sections have been obtained by subtracting the theoretical scattering cross sections. A good agreement is observed between the present data of photoeffect cross sections and Scofield's theoretical data.

Electron-Impact Ionization Cross Section Database

National Institute of Standards and Technology Data Gateway

SRD 107 Electron-Impact Ionization Cross Section Database (Web, free access)   This is a database primarily of total ionization cross sections of molecules by electron impact. The database also includes cross sections for a small number of atoms and energy distributions of ejected electrons for H, He, and H2. The cross sections were calculated using the Binary-Encounter-Bethe (BEB) model, which combines the Mott cross section with the high-incident energy behavior of the Bethe cross section. Selected experimental data are included.

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

Bencze, G.; Chandler, C.

It is shown that the electric polarizability of the deuteron produces negligible effect on the cross section of deuteron induced rearrangement reactions even at extremely low energies. This assessment is based on simple analytical formulas, derived on the basis of {ital N}-particle scattering theory by means of the general two-potential formalism, including Coulomb and exchange effects. It is shown on the basis of general physical arguments that the polarizability effects at very low energies are entirely contained in a multiplicative enhancement factor that differs from 1 by at most a few percent. As a result enhancement of ({ital d},{ital p})more » relative to ({ital d},{ital n}) reactions is not possible by the Oppenheimer-Phillips mechanism.« less

A model for accretion of the terrestrial planets

NASA Technical Reports Server (NTRS)

Weidenschilling, S. J.

1974-01-01

One possible origin of the terrestrial planets involves their formation by gravitational accretion of particles originally in Keplerian orbits about the sun. Some implications of this theory are considered. A formal expression for the rate of mass accretion by a planet is developed. The formal singularity of the gravitational collision cross section for low relative velocities is shown to be without physical significance when the accreting bodies are in heliocentric orbits. The distribution of particle velocities relative to an accreting planet is considered; the mean velocity increases with time. The internal temperature of an accreting planet is shown to depend simply on the accretion rate. A simple and physically reasonable approximate expression for a planetary accretion rate is proposed.

Quantum-mechanical predictions of DNA and RNA ionization by energetic proton beams.

PubMed

Galassi, M E; Champion, C; Weck, P F; Rivarola, R D; Fojón, O; Hanssen, J

2012-04-07

Among the numerous constituents of eukaryotic cells, the DNA macromolecule is considered as the most important critical target for radiation-induced damages. However, up to now ion-induced collisions on DNA components remain scarcely approached and theoretical support is still lacking for describing the main ionizing processes. In this context, we here report a theoretical description of the proton-induced ionization of the DNA and RNA bases as well as the sugar-phosphate backbone. Two different quantum-mechanical models are proposed: the first one based on a continuum distorted wave-eikonal initial state treatment and the second perturbative one developed within the first Born approximation with correct boundary conditions (CB1). Besides, the molecular structure information of the biological targets studied here was determined by ab initio calculations with the Gaussian 09 software at the restricted Hartree-Fock level of theory with geometry optimization. Doubly, singly differential and total ionization cross sections also provided by the two models were compared for a large range of incident and ejection energies and a very good agreement was observed for all the configurations investigated. Finally, in comparison with the rare experiment, we have noted a large underestimation of the total ionization cross sections of uracil impacted by 80 keV protons,whereas a very good agreement was shown with the recently reported ionization cross sections for protons on adenine, at both the differential and the total scale.

On similarity of various reactor spectra and 235U prompt fission neutron spectrum.

PubMed

Košťál, Michal; Matěj, Zdeněk; Losa, Evžen; Huml, Ondřej; Štefánik, Milan; Cvachovec, František; Schulc, Martin; Jánský, Bohumil; Novák, Evžen; Harutyunyan, Davit; Rypar, Vojtěch

2018-05-01

A well-defined neutron spectrum is an essential tool not only for calibration and testing of neutron detectors used in dosimetry and spectroscopy but also for validation and verification of evaluated cross sections. A new evaluation of thermal-neutron induced 235 U PFNS was performed by the International Atomic Energy Agency (IAEA) in the CIELO (Collaborative International Evaluated Library Organisation Project) project; new measurements of Spectral Averaged Cross sections averaged in the evaluated spectrum are to be obtained. In general, a neutron spectrum in the core is not identical to the pure fission one because fission neutrons undergo many scattering reactions, but it can be shown that PFNS and reactor spectra become undistinguishable from a certain energy boundary. This limit is important for experiments, because when the studied reaction threshold is over this limit, the spectral averaged cross sections in PFNS can be derived from the measured reactions in the reactor core. The evaluation of the neutron spectrum measurements in three different thermal-reactor cores shows that this lower limit is around the energy of 5.5 - 6 MeV. Above this energy the reactor spectra becomes identical with the 235 U PFNS. IAEA CIELO PFNS is within 5% of the measured PFNS from 10 to 14 MeV in a LR-0 reactor, while ENDF/B-VII evaluated PFNS underestimated measured neutron spectra. Copyright © 2018 Elsevier Ltd. All rights reserved.

Cosmic ray knee and new physics at the TeV scale

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

Barceló, Roberto; Masip, Manuel; Mastromatteo, Iacopo, E-mail: rbarcelo@ugr.es, E-mail: masip@ugr.es, E-mail: mastroma@sissa.it

2009-06-01

We analyze the possibility that the cosmic ray knee appears at an energy threshold where the proton-dark matter cross section becomes large due to new TeV physics. It has been shown that such interactions could break the proton and produce a diffuse gamma ray flux consistent with MILAGRO observations. We argue that this hypothesis implies knees that scale with the atomic mass for the different nuclei, as KASKADE data seem to indicate. We find that to explain the change in the spectral index in the flux from E{sup −2.7} to E{sup −3.1} the cross section must grow like E{sup 0.4+β}more » above the knee, where β = 0.3–0.6 parametrizes the energy dependence of the age (τ∝E{sup −β}) of the cosmic rays reaching the Earth. The hypothesis also requires mbarn cross sections (that could be modelled with TeV gravity) and large densities of dark matter (that could be clumped around the sources of cosmic rays). We argue that neutrinos would also exhibit a threshold at E = (m{sub χ}/m{sub p}) E{sub knee} ≈ 10{sup 8} GeV where their interaction with a nucleon becomes strong. Therefore, the observation at ICECUBE or ANITA of standard neutrino events above this threshold would disprove the scenario.« less

Temporal scaling of the growth dependent optical properties of microalgae

NASA Astrophysics Data System (ADS)

Zhao, J. M.; Ma, C. Y.; Liu, L. H.

2018-07-01

The optical properties of microalgae are basic parameters for analyzing light field distribution in photobioreactors (PBRs). With the growth of microalgae cell, their optical properties will vary with growth time due to accumulation of pigment and lipid, cell division and metabolism. In this work, we report a temporal scaling behavior of the growth dependent optical properties of microalgae cell suspensions with both experimental and theoretical evidence presented. A new concept, the temporal scaling function (TSF), defined as the ratio of absorption or scattering cross-sections at growth phase to that at stationary phase, is introduced to characterize the temporal scaling behavior. The temporal evolution and temporal scaling characteristics of the absorption and scattering cross-sections of three example microalgae species, Chlorella vulgaris, Chlorella pyrenoidosa, and Chlorella protothecoides, were experimentally studied at spectral range 380-850 nm. It is shown that the TSFs of the absorption and scattering cross-sections for different microalgae species are approximately constant at different wavelength, which confirms theoretical predictions very well. With the aid of the temporal scaling relation, the optical properties at any growth time can be calculated based on those measured at stationary phase, hence opens a new way to determine the time-dependent optical properties of microalgae. The findings of this work will help the understanding of time dependent optical properties of microalgae and facilitate their applications in light field analysis in PBRs design.

Bak-Tang-Wiesenfeld model in the upper critical dimension: Induced criticality in lower-dimensional subsystems

NASA Astrophysics Data System (ADS)

Dashti-Naserabadi, H.; Najafi, M. N.

2017-10-01

We present extensive numerical simulations of Bak-Tang-Wiesenfeld (BTW) sandpile model on the hypercubic lattice in the upper critical dimension Du=4 . After re-extracting the critical exponents of avalanches, we concentrate on the three- and two-dimensional (2D) cross sections seeking for the induced criticality which are reflected in the geometrical and local exponents. Various features of finite-size scaling (FSS) theory have been tested and confirmed for all dimensions. The hyperscaling relations between the exponents of the distribution functions and the fractal dimensions are shown to be valid for all dimensions. We found that the exponent of the distribution function of avalanche mass is the same for the d -dimensional cross sections and the d -dimensional BTW model for d =2 and 3. The geometrical quantities, however, have completely different behaviors with respect to the same-dimensional BTW model. By analyzing the FSS theory for the geometrical exponents of the two-dimensional cross sections, we propose that the 2D induced models have degrees of similarity with the Gaussian free field (GFF). Although some local exponents are slightly different, this similarity is excellent for the fractal dimensions. The most important one showing this feature is the fractal dimension of loops df, which is found to be 1.50 ±0.02 ≈3/2 =dfGFF .

Stroke Volume estimation using aortic pressure measurements and aortic cross sectional area: Proof of concept.

PubMed

Kamoi, S; Pretty, C G; Chiew, Y S; Pironet, A; Davidson, S; Desaive, T; Shaw, G M; Chase, J G

2015-08-01

Accurate Stroke Volume (SV) monitoring is essential for patient with cardiovascular dysfunction patients. However, direct SV measurements are not clinically feasible due to the highly invasive nature of measurement devices. Current devices for indirect monitoring of SV are shown to be inaccurate during sudden hemodynamic changes. This paper presents a novel SV estimation using readily available aortic pressure measurements and aortic cross sectional area, using data from a porcine experiment where medical interventions such as fluid replacement, dobutamine infusions, and recruitment maneuvers induced SV changes in a pig with circulatory shock. Measurement of left ventricular volume, proximal aortic pressure, and descending aortic pressure waveforms were made simultaneously during the experiment. From measured data, proximal aortic pressure was separated into reservoir and excess pressures. Beat-to-beat aortic characteristic impedance values were calculated using both aortic pressure measurements and an estimate of the aortic cross sectional area. SV was estimated using the calculated aortic characteristic impedance and excess component of the proximal aorta. The median difference between directly measured SV and estimated SV was -1.4ml with 95% limit of agreement +/- 6.6ml. This method demonstrates that SV can be accurately captured beat-to-beat during sudden changes in hemodynamic state. This novel SV estimation could enable improved cardiac and circulatory treatment in the critical care environment by titrating treatment to the effect on SV.

Prospects of heavy and superheavy element production via inelastic nucleus-nucleus collisions - from 238U+238U to18O+254Es

NASA Astrophysics Data System (ADS)

Schädel, Matthias

2016-12-01

Multi-nucleon transfer reactions, frequently termed deep-inelastic, between heavy-ion projectiles and actinide targets provide prospects to synthesize unknown isotopes of heavy actinides and superheavy elements with neutron numbers beyond present limits. The 238U on 238U reaction, which revealed essential aspects of those nuclear reactions leading to surviving heavy nuclides, mainly produced in 3n and 4n evaporation channels, is discussed in detail. Positions and widths of isotope distributions are compared. It is shown, as a general rule, that cross sections peak at irradiation energies about 10% above the Coulomb barrier. Heavy target nuclei are essential for maximizing cross sections. Experimental results from the 238U on 248Cm reaction, including empirical extrapolations, are compared with theoretical model calculations predicting relatively high cross sections for neutron-rich nuclei. Experiments to test the validity of such predictions are proposed. Comparisons between rather symmetric heavy-ion reactions like 238U on 248Cm (or heavier targets up to 254Es) with very asymmetric ones like 18O on 254Es reveal that the ones with 238U as a projectile have the highest potential in the superheavy element region while the latter ones can be advantageous for the synthesis of heavy actinide isotopes. Concepts for highly efficient recoil separators designed for transfer products are presented.

Measurement of the tt¯ production cross-section as a function of jet multiplicity and jet transverse momentum in 7 TeV proton-proton collisions with the ATLAS detector

DOE PAGES

Aad, G.

2015-01-08

Tmore » he t t ¯ production cross-section dependence on jet multiplicity and jet transverse momentum is reported for proton-proton collisions at a centre-of-mass energy of 7 eV in the single-lepton channel. his data was collected with the ALAS detector at the CERN Large Hadron Collider and comprise the full 2011 data sample corresponding to an integrated luminosity of 4.6 fb –1. Differential cross-sections are presented as a function of the jet multiplicity for up to eight jets using jet transverse momentum thresholds of 25, 40, 60, and 80 GeV, and as a function of jet transverse momentum up to the fifth jet. he results are shown after background subtraction and corrections for all known detector effects, within a kinematic range closely matched to the experimental acceptance. Several QCD-based Monte Carlo models are compared with the results. Sensitivity to the parton shower modelling is found at the higher jet multiplicities, at high transverse momentum of the leading jet and in the transverse momentum spectrum of the fifth leading jet. As a result, the MC@NLO+HERWIG MC is found to predict too few events at higher jet multiplicities.« less

Bak-Tang-Wiesenfeld model in the upper critical dimension: Induced criticality in lower-dimensional subsystems.

PubMed

Dashti-Naserabadi, H; Najafi, M N

2017-10-01

We present extensive numerical simulations of Bak-Tang-Wiesenfeld (BTW) sandpile model on the hypercubic lattice in the upper critical dimension D_{u}=4. After re-extracting the critical exponents of avalanches, we concentrate on the three- and two-dimensional (2D) cross sections seeking for the induced criticality which are reflected in the geometrical and local exponents. Various features of finite-size scaling (FSS) theory have been tested and confirmed for all dimensions. The hyperscaling relations between the exponents of the distribution functions and the fractal dimensions are shown to be valid for all dimensions. We found that the exponent of the distribution function of avalanche mass is the same for the d-dimensional cross sections and the d-dimensional BTW model for d=2 and 3. The geometrical quantities, however, have completely different behaviors with respect to the same-dimensional BTW model. By analyzing the FSS theory for the geometrical exponents of the two-dimensional cross sections, we propose that the 2D induced models have degrees of similarity with the Gaussian free field (GFF). Although some local exponents are slightly different, this similarity is excellent for the fractal dimensions. The most important one showing this feature is the fractal dimension of loops d_{f}, which is found to be 1.50±0.02≈3/2=d_{f}^{GFF}.

Quantum-mechanical predictions of DNA and RNA ionization by energetic proton beams

NASA Astrophysics Data System (ADS)

Galassi, M. E.; Champion, C.; Weck, P. F.; Rivarola, R. D.; Fojón, O.; Hanssen, J.

2012-04-01

Among the numerous constituents of eukaryotic cells, the DNA macromolecule is considered as the most important critical target for radiation-induced damages. However, up to now ion-induced collisions on DNA components remain scarcely approached and theoretical support is still lacking for describing the main ionizing processes. In this context, we here report a theoretical description of the proton-induced ionization of the DNA and RNA bases as well as the sugar-phosphate backbone. Two different quantum-mechanical models are proposed: the first one based on a continuum distorted wave-eikonal initial state treatment and the second perturbative one developed within the first Born approximation with correct boundary conditions (CB1). Besides, the molecular structure information of the biological targets studied here was determined by ab initio calculations with the Gaussian 09 software at the restricted Hartree-Fock level of theory with geometry optimization. Doubly, singly differential and total ionization cross sections also provided by the two models were compared for a large range of incident and ejection energies and a very good agreement was observed for all the configurations investigated. Finally, in comparison with the rare experiment, we have noted a large underestimation of the total ionization cross sections of uracil impacted by 80 keV protons, whereas a very good agreement was shown with the recently reported ionization cross sections for protons on adenine, at both the differential and the total scale.

Quantitative x-ray photoelectron spectroscopy: Quadrupole effects, shake-up, Shirley background, and relative sensitivity factors from a database of true x-ray photoelectron spectra

NASA Astrophysics Data System (ADS)

Seah, M. P.; Gilmore, I. S.

2006-05-01

An analysis is provided of the x-ray photoelectron spectroscopy (XPS) intensities measured in the National Physical Laboratory (NPL) XPS database for 46 solid elements. This present analysis does not change our previous conclusions concerning the excellent correlation between experimental intensities, following deconvolving the spectra with angle-averaged reflection electron energy loss data, and the theoretical intensities involving the dipole approximation using Scofield’s cross sections. Here, more recent calculations for cross sections by Trzhaskovskaya involving quadrupole terms are evaluated and it is shown that their cross sections diverge from the experimental database results by up to a factor of 5. The quadrupole angular terms lead to small corrections that are close to our measurement limit but do appear to be supported in the present analysis. Measurements of the extent of shake-up for the 46 elements broadly agree with the calculations of Yarzhemsky but not in detail. The predicted constancy in the shake-up contribution by Yarzhemsky implies that the use of the Shirley background will lead to a peak area that is a constant fraction of the true peak area including the shake-up intensities. However, the measured variability of the shake-up contribution makes the Shirley background invalid for quantification except for situations where the sensitivity factors are from reference samples similar to those being analyzed.

Composition of Renaissance paint layers: simultaneous particle induced X-ray emission and backscattering spectrometry.

PubMed

de Viguerie, L; Beck, L; Salomon, J; Pichon, L; Walter, Ph

2009-10-01

Particle induced X-ray emission spectroscopy (PIXE) is now routinely used in the field of cultural heritage. Various setups have been developed to investigate the elemental composition of wood/canvas paintings or of cross-section samples. However, it is not possible to obtain information concerning the quantity of organic binder. Backscattering spectrometry (BS) can be a useful complementary method to overcome this limitation. In the case of paint layers, PIXE brings the elemental composition (major elements to traces) and the BS spectrum can give access to the proportion of pigment and binder. With the use of 3 MeV protons for PIXE and BS simultaneously, it was possible to perform quantitative analysis including C and O for which the non-Rutherford cross sections are intense. Furthermore, with the use of the same conditions for PIXE and BS, the experiment time and the potential damage by the ion beam were reduced. The results obtained with the external beam of the Accélérateur Grand Louvre pour l'Analyse Elementaire (AGLAE) facility on various test painting samples and on cross sections from Italian Renaissance masterpieces are shown. Simultaneous combination of PIXE and BS leads to a complete characterization of the paint layers: elemental composition and proportion of the organic binder have been determined and thus provide useful information about ancient oil painting recipes.

Measurement of the tt¯ production cross-section as a function of jet multiplicity and jet transverse momentum in 7 TeV proton-proton collisions with the ATLAS detector

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

Aad, G.

Tmore » he t t ¯ production cross-section dependence on jet multiplicity and jet transverse momentum is reported for proton-proton collisions at a centre-of-mass energy of 7 eV in the single-lepton channel. his data was collected with the ALAS detector at the CERN Large Hadron Collider and comprise the full 2011 data sample corresponding to an integrated luminosity of 4.6 fb –1. Differential cross-sections are presented as a function of the jet multiplicity for up to eight jets using jet transverse momentum thresholds of 25, 40, 60, and 80 GeV, and as a function of jet transverse momentum up to the fifth jet. he results are shown after background subtraction and corrections for all known detector effects, within a kinematic range closely matched to the experimental acceptance. Several QCD-based Monte Carlo models are compared with the results. Sensitivity to the parton shower modelling is found at the higher jet multiplicities, at high transverse momentum of the leading jet and in the transverse momentum spectrum of the fifth leading jet. As a result, the MC@NLO+HERWIG MC is found to predict too few events at higher jet multiplicities.« less

Surface Passivation for Reliable Measurement of Bulk Electronic Properties of Heterojunction Devices.

PubMed

Bissig, Benjamin; Guerra-Nunez, Carlos; Carron, Romain; Nishiwaki, Shiro; La Mattina, Fabio; Pianezzi, Fabian; Losio, Paolo A; Avancini, Enrico; Reinhard, Patrick; Haass, Stefan G; Lingg, Martina; Feurer, Thomas; Utke, Ivo; Buecheler, Stephan; Tiwari, Ayodhya N

2016-10-01

Quantum efficiency measurements of state of the art Cu(In,Ga)Se 2 (CIGS) thin film solar cells reveal current losses in the near infrared spectral region. These losses can be ascribed to inadequate optical absorption or poor collection of photogenerated charge carriers. Insight on the limiting mechanism is crucial for the development of more efficient devices. The electron beam induced current measurement technique applied on device cross-sections promises an experimental access to depth resolved information about the charge carrier collection probability. Here, this technique is used to show that charge carrier collection in CIGS deposited by multistage co-evaporation at low temperature is efficient over the optically active region and collection losses are minor as compared to the optical ones. Implications on the favorable absorber design are discussed. Furthermore, it is observed that the measurement is strongly affected by cross-section surface recombination and an accurate determination of the collection efficiency is not possible. Therefore it is proposed and shown that the use of an Al 2 O 3 layer deposited onto the cleaved cross-section significantly improves the accuracy of the measurement by reducing the surface recombination. A model for the passivation mechanism is presented and the passivation concept is extended to other solar cell technologies such as CdTe and Cu 2 (Zn,Sn)(S,Se) 4 . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reducing cross-sectional data using a genetic algorithm method and effects on cross-section geometry and steady-flow profiles

USGS Publications Warehouse

Berenbrock, Charles E.

2015-01-01

The effects of reduced cross-sectional data points on steady-flow profiles were also determined. Thirty-five cross sections of the original steady-flow model of the Kootenai River were used. These two methods were tested for all cross sections with each cross section resolution reduced to 10, 20 and 30 data points, that is, six tests were completed for each of the thirty-five cross sections. Generally, differences from the original water-surface elevation were smaller as the number of data points in reduced cross sections increased, but this was not always the case, especially in the braided reach. Differences were smaller for reduced cross sections developed by the genetic algorithm method than the standard algorithm method.

Meson Production and Space Radiation

NASA Astrophysics Data System (ADS)

Norbury, John; Blattnig, Steve; Norman, Ryan; Aghara, Sukesh

Protecting astronauts from the harmful effects of space radiation is an important priority for long duration space flight. The National Council on Radiation Protection (NCRP) has recently recommended that pion and other mesons should be included in space radiation transport codes, especially in connection with the Martian atmosphere. In an interesting accident of nature, the galactic cosmic ray spectrum has its peak intensity near the pion production threshold. The Boltzmann transport equation is structured in such a way that particle production cross sec-tions are multiplied by particle flux. Therefore, the peak of the incident flux of the galactic cosmic ray spectrum is more important than other regions of the spectrum and cross sections near the peak are enhanced. This happens with pion cross sections. The MCNPX Monte-Carlo transport code now has the capability of transporting heavy ions, and by using a galactic cosmic ray spectrum as input, recent work has shown that pions contribute about twenty percent of the dose from galactic cosmic rays behind a shield of 20 g/cm2 aluminum and 30 g/cm2 water. It is therefore important to include pion and other hadron production in transport codes designed for space radiation studies, such as HZETRN. The status of experimental hadron production data for energies relevant to space radiation will be reviewed, as well as the predictive capa-bilities of current theoretical hadron production cross section and space radiation transport models. Charged pions decay into muons and neutrinos, and neutral pions decay into photons. An electromagnetic cascade is produced as these particles build up in a material. The cascade and transport of pions, muons, electrons and photons will be discussed as they relate to space radiation. The importance of other hadrons, such as kaons, eta mesons and antiprotons will be considered as well. Efficient methods for calculating cross sections for meson production in nucleon-nucleon and nucleus-nucleus reactions will be presented. The NCRP has also recom-mended that more attention should be paid to neutron and light ion transport. The coupling of neutrons, light ions, mesons and other hadrons will be discussed.

a Time-Dependent Many-Electron Approach to Atomic and Molecular Interactions

NASA Astrophysics Data System (ADS)

Runge, Keith

A new methodology is developed for the description of electronic rearrangement in atomic and molecular collisions. Using the eikonal representation of the total wavefunction, time -dependent equations are derived for the electronic densities within the time-dependent Hartree-Fock approximation. An averaged effective potential which ensures time reversal invariance is used to describe the effect of the fast electronic transitions on the slower nuclear motions. Electron translation factors (ETF) are introduced to eliminate spurious asymptotic couplings, and a local ETF is incorporated into a basis of traveling atomic orbitals. A reference density is used to describe local electronic relaxation and to account for the time propagation of fast and slow motions, and is shown to lead to an efficient integration scheme. Expressions for time-dependent electronic populations and polarization parameters are given. Electronic integrals over Gaussians including ETFs are derived to extend electronic state calculations to dynamical phenomena. Results of the method are in good agreement with experimental data for charge transfer integral cross sections over a projectile energy range of three orders of magnitude in the proton-Hydrogen atom system. The more demanding calculations of integral alignment, state-to-state integral cross sections, and differential cross sections are found to agree well with experimental data provided care is taken to include ETFs in the calculation of electronic integrals and to choose the appropriate effective potential. The method is found to be in good agreement with experimental data for the calculation of charge transfer integral cross sections and state-to-state integral cross sections in the one-electron heteronuclear Helium(2+)-Hydrogen atom system and in the two-electron system, Hydrogen atom-Hydrogen atom. Time-dependent electronic populations are seen to oscillate rapidly in the midst of collision event. In particular, multiple exchanges of the electron are seen to occur in the proton-Hydrogen atom system at low collision energies. The concepts and results derived from the approach provide new insight into the dynamics of nuclear screening and electronic rearrangement in atomic collisions.

On-the-Fly Generation of Differential Resonance Scattering Probability Distribution Functions for Monte Carlo Codes

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

Davidson, Eva E.; Martin, William R.

Current Monte Carlo codes use one of three models: (1) the asymptotic scattering model, (2) the free gas scattering model, or (3) the S(α,β) model, depending on the neutron energy and the specific Monte Carlo code. This thesis addresses the consequences of using the free gas scattering model, which assumes that the neutron interacts with atoms in thermal motion in a monatomic gas in thermal equilibrium at material temperature, T. Most importantly, the free gas model assumes the scattering cross section is constant over the neutron energy range, which is usually a good approximation for light nuclei, but not formore » heavy nuclei where the scattering cross section may have several resonances in the epithermal region. Several researchers in the field have shown that the exact resonance scattering model is temperaturedependent, and neglecting the resonances in the lower epithermal range can under-predict resonance absorption due to the upscattering phenomenon mentioned above, leading to an over-prediction of keff by several hundred pcm. Existing methods to address this issue involve changing the neutron weights or implementing an extra rejection scheme in the free gas sampling scheme, and these all involve performing the collision analysis in the center-of-mass frame, followed by a conversion back to the laboratory frame to continue the random walk of the neutron. The goal of this paper was to develop a sampling methodology that (1) accounted for the energydependent scattering cross sections in the collision analysis and (2) was performed in the laboratory frame,avoiding the conversion to the center-of-mass frame. The energy dependence of the scattering cross section was modeled with even-ordered polynomials (2nd and 4th order) to approximate the scattering cross section in Blackshaw’s equations for the moments of the differential scattering PDFs. These moments were used to sample the outgoing neutron speed and angle in the laboratory frame on-the-fly during the random walk of the neutron. Results for criticality studies on fuel pin and fuel assembly calculations using methods developed in this dissertation showed very close comparison to results using the reference Dopplerbroadened rejection correction (DBRC) scheme.« less

On-the-Fly Generation of Differential Resonance Scattering Probability Distribution Functions for Monte Carlo Codes

DOE PAGES

Davidson, Eva E.; Martin, William R.

2017-05-26

Current Monte Carlo codes use one of three models: (1) the asymptotic scattering model, (2) the free gas scattering model, or (3) the S(α,β) model, depending on the neutron energy and the specific Monte Carlo code. This thesis addresses the consequences of using the free gas scattering model, which assumes that the neutron interacts with atoms in thermal motion in a monatomic gas in thermal equilibrium at material temperature, T. Most importantly, the free gas model assumes the scattering cross section is constant over the neutron energy range, which is usually a good approximation for light nuclei, but not formore » heavy nuclei where the scattering cross section may have several resonances in the epithermal region. Several researchers in the field have shown that the exact resonance scattering model is temperaturedependent, and neglecting the resonances in the lower epithermal range can under-predict resonance absorption due to the upscattering phenomenon mentioned above, leading to an over-prediction of keff by several hundred pcm. Existing methods to address this issue involve changing the neutron weights or implementing an extra rejection scheme in the free gas sampling scheme, and these all involve performing the collision analysis in the center-of-mass frame, followed by a conversion back to the laboratory frame to continue the random walk of the neutron. The goal of this paper was to develop a sampling methodology that (1) accounted for the energydependent scattering cross sections in the collision analysis and (2) was performed in the laboratory frame,avoiding the conversion to the center-of-mass frame. The energy dependence of the scattering cross section was modeled with even-ordered polynomials (2nd and 4th order) to approximate the scattering cross section in Blackshaw’s equations for the moments of the differential scattering PDFs. These moments were used to sample the outgoing neutron speed and angle in the laboratory frame on-the-fly during the random walk of the neutron. Results for criticality studies on fuel pin and fuel assembly calculations using methods developed in this dissertation showed very close comparison to results using the reference Dopplerbroadened rejection correction (DBRC) scheme.« less

Possibilities and limitations of rod-beam theories. [nonlinear distortion tensor and nonlinear stress tensors

NASA Technical Reports Server (NTRS)

Peterson, D.

1979-01-01

Rod-beam theories are founded on hypotheses such as Bernouilli's suggesting flat cross-sections under deformation. These assumptions, which make rod-beam theories possible, also limit the accuracy of their analysis. It is shown that from a certain order upward terms of geometrically nonlinear deformations contradict the rod-beam hypotheses. Consistent application of differential geometry calculus also reveals differences from existing rod theories of higher order. These differences are explained by simple examples.

Wave multiple scattering by a finite number of unclosed circular cylinders

NASA Technical Reports Server (NTRS)

Veliyev, E. I.; Veremey, V. V.

1984-01-01

The boundary value problem of plane H-polarized electromagnetic wave multiple scattering by a finite number of unclosed circular cylinders is solved. The solution is obtained by two different methods: the method of successive scattering and the method of partial matrix inversion for simultaneous dual equations. The advantages of the successive scattering method are shown. Computer calculations of the suface currents and the total cross section are presented for the structure of two screens.

Variability of Hormonal Stress Markers and Stress Responses in a Large Cross-Sectional Sample of Elephant Seals

DTIC Science & Technology

2014-09-30

hormones and function in elephant seals; 3) determine the impact of baseline variation in aldosterone on electrolyte balance in elephant seals; 4...may have broad implications for marine mammal species. Task 3 – Impact of aldosterone variability on osmolality Work on the Parent Project and...a parallel project on bottlenose dolphins has shown the importance of aldosterone as a stress hormone in marine mammals. Aldosterone covaries with

Variability of Hormonal Stress Markers and Stress Responses in a Large Cross-Sectional Sample of Elephant Seals

DTIC Science & Technology

2015-09-30

hormones and function in elephant seals; 3) determine the impact of baseline variation in aldosterone on electrolyte balance in elephant seals; 4...3 – Impact of aldosterone variability on osmolality Work on the Parent Project and a parallel project on bottlenose dolphins has shown the...importance of aldosterone as a stress hormone in marine mammals. Aldosterone covaries with cortisol in many groups (Figure 4) and ACTH challenges in the

Low-Impedance Compact Modulators Capable of Generating Intense Ultra-fast Rising Nanosecond Waveforms

DTIC Science & Technology

2006-10-31

spark gap is shown in Fig. 1. The Blumleins were constructed from copper plates separated by laminated layered Kapton (polyimide) dielectrics. Scaling... convolution factor. The diamond/GaAs heterojunction response is limited to a very thin layer across the cross section between amorphic diamond and GaAs...were fastened to electrode mounts and passed through the cast material of the base before it hardened. A thick kapton laminate 1.2 cm wide separated

Direct imaging of Cl- and Cu-induced short-circuit efficiency changes in CdTe solar cells

DOE PAGES

Poplawsky, Jonathan D.; Parish, Chad M.; Leonard, Donovan N.; ...

2014-05-30

To achieve high-efficiency polycrystalline CdTe-based thin-film solar cells, the CdTe absorbers must go through a post-deposition CdCl 2 heat treatment followed by a Cu diffusion step. To better understand the roles of each treatment with regard to improving grains, grain boundaries, and interfaces, CdTe solar cells with and without Cu diffusion and CdCl 2 heat treatments are investigated using cross-sectional electron beam induced current, electron backscatter diffraction, and scanning transmission electron microscope techniques. The evolution of the cross-sectional carrier collection profile due to these treatments that cause an increase in short-circuit current and higher open-circuit voltage are identified. Additionally, anmore » increased carrier collection in grain boundaries after either/both of these treatments is revealed. The increased current at the grain boundaries is shown to be due to the presence of a space charge region with an intrinsic carrier collection profile width of ≈350 nm. Scanning transmission electron microscope electron-energy loss spectroscopy shows a decreased Te and increased Cl concentration in grain boundaries after treatment, which causes the inversion. Furthermore, each treatment improves the overall carrier collection efficiency of the cell separately, and, therefore, the benefits realized by each treatment are shown to be independent of each other.« less

Dynamic correlation effects in fully differential cross sections for 75-keV proton-impact ionization of helium

NASA Astrophysics Data System (ADS)

Niu, Xiaojie; Sun, Shiyan; Wang, Fujun; Jia, Xiangfu

2017-08-01

The effect of final-state dynamic correlation is investigated for helium single ionization by 75-keV proton impact analyzing fully differential cross sections (FDCS). The final state is represented by a continuum correlated wave (CCW-PT) function which accounts for the interaction between the projectile and the residual target ion (PT interaction). This continuum correlated wave function partially includes the correlation of electron-projectile and electron-target relative motion as coupling terms of the wave equation. The transition matrix is evaluated using the CCW-PT function and the Born initial state. The analytical expression of the transition matrix has been obtained. We have shown that this series is strongly convergent and analyzed the contribution of their different terms to the FDCS within the perturbation method. Illustrative computations are performed in the scattering plane and in the perpendicular plane. Both the correlation effects and the PT interaction are checked by the preset calculations. Our results are compared with absolute experimental data as well as other theoretical models. We have shown that the dynamic correlation plays an important role in the single ionization of atoms by proton impact at intermediate projectile energies, especially at large transverse momentum transfer. While overall agreement between theory and the experimental data is encouraging, detailed agreement is lacking. The need for more theoretical and experimental work is emphasized.

Mg2Sn heterostructures on Si(111) substrate

NASA Astrophysics Data System (ADS)

Dózsa, L.; Galkin, N. G.; Pécz, B.; Osváth, Z.; Zolnai, Zs.; Németh, A.; Galkin, K. N.; Chernev, I. M.; Dotsenko, S. A.

2017-05-01

Thin un-doped and Al doped polycrystalline Mg-stannide films consisting mainly of Mg2Sn semiconductor phase have been grown by deposition of Sn-Mg multilayers on Si(111) p-type wafers at room temperature and annealing at 150 °C. Rutherford backscattering measurement spectroscopy (RBS) were used to determine the amount of Mg and Sn in the structures. Raman spectroscopy has shown the layers contain Mg2Sn phase. Cross sectional transmission electron microscopy (XTEM) measurements have identified Mg2Sn nanocrystallites in hexagonal and cubic phases without epitaxial orientation with respect to the Si(111) substrate. Significant oxygen concentration was found in the layer both by RBS and TEM. The electrical measurements have shown laterally homogeneous conductivity in the grown layer. The undoped Mg2Sn layers show increasing resistivity with increasing temperature indicating the scattering process dominates the resistance of the layers, i.e. large concentration of point defects was generated in the layer during the growth process. The Al doped layer shows increase of the resistance at low temperature caused by freeze out of free carriers in the Al doped Mg2Sn layer. The measurements indicate the necessity of protective layer grown over the Mg2Sn layers, and a short time delay between sample preparation and cross sectionalTEM analysis, since the unprotected layer is degraded by the interaction with the ambient.

Experiments on Antiprotons: Antiproton-Nucleon Cross Sections

DOE R&D Accomplishments Database

Chamberlain, Owen; Keller, Donald V.; Mermond, Ronald; Segre, Emilio; Steiner, Herbert M.; Ypsilantis, Tom

1957-07-22

In this paper experiments are reported on annihilation and scattering of antiprotons in H{sub 2}O , D{sub 2}O, and O{sub 2}. From the data measured it is possible to obtain an antiproton-proton and an antiproton-deuteron cross section at 457 Mev (lab). Further analysis gives the p-p and p-n cross sections as 104 mb for the p-p reaction cross section and 113 mb for the p-n reaction cross section. The respective annihilation cross sections are 89 and 74 mb. The Glauber correction necessary in order to pass from the p-d to the p-n cross section by subtraction of the p-p cross section is unfortunately large and somewhat uncertain. The data are compared with the p-p and p-n cross sections and with other results on p-p collisions.

Study of BenW (n = 1-12) clusters: An electron collision perspective

NASA Astrophysics Data System (ADS)

Modak, Paresh; Kaur, Jaspreet; Antony, Bobby

2017-08-01

This article explores electron scattering cross sections by Beryllium-Tungsten clusters (BenW). Beryllium and tungsten are important elements for plasma facing wall components, especially for the deuterium/tritium phase of ITER and in the recently installed JET. The present study focuses on different electron impact interactions in terms of elastic cross section (Qel), inelastic cross section (Qinel), ionization cross section (Qion), and momentum transfer cross section (Qmtcs) for the first twelve clusters belonging to the BenW family. It also predicts the evolution of the cross section with the size of the cluster. These cross sections are used as an input to model processes in plasma. The ionization cross section presented here is compared with the available reported data. This is the first comprehensive report on cross section data for all the above-mentioned scattering channels, to the best of our knowledge. Such broad analysis of cross section data gives vital insight into the study of local chemistry of electron interactions with BenW (n = 1-12) clusters in plasma.

High statistics study of the reaction γp → pπ0 η

NASA Astrophysics Data System (ADS)

Gutz, E.; Crede, V.; Sokhoyan, V.; van Pee, H.; Anisovich, A. V.; Bacelar, J. C. S.; Bantes, B.; Bartholomy, O.; Bayadilov, D.; Beck, R.; Beloglazov, Y. A.; Castelijns, R.; Dutz, H.; Elsner, D.; Ewald, R.; Frommberger, F.; Fuchs, M.; Funke, Ch.; Gregor, R.; Gridnev, A. B.; Hillert, W.; Hoffmeister, Ph.; Horn, I.; Jaegle, I.; Junkersfeld, J.; Kalinowsky, H.; Kammer, S.; Kleber, V.; Klein, Frank; Klein, Friedrich; Klempt, E.; Kotulla, M.; Krusche, B.; Lang, M.; Löhner, H.; Lopatin, I. V.; Lugert, S.; Mertens, T.; Messchendorp, J. G.; Metag, V.; Nanova, M.; Nikonov, V. A.; Novinsky, D.; Novotny, R.; Ostrick, M.; Pant, L.; Pfeiffer, M.; Piontek, D.; Roy, A.; Sarantsev, A. V.; Schmidt, Ch.; Schmieden, H.; Shende, S.; Süle, A.; Sumachev, V. V.; Szczepanek, T.; Thiel, A.; Thoma, U.; Trnka, D.; Varma, R.; Walther, D.; Wendel, Ch.; Wilson, A.

2014-04-01

Photoproduction off protons of the pπ 0 η three-body final state was studied with the Crystal Barrel/TAPS detector, at the electron stretcher accelerator ELSA in Bonn, for incident energies from the π 0 η production threshold up to 2.5 GeV. Differential cross sections and the total cross sections are presented. The use of linearly polarized photons gives access to the polarization observables Σ, I s , and I c , the latter two characterize beam asymmetries in case of three-body final states. Δ(1232) η, N(1535)1/2- π, and pa 0(980) are the dominant isobars contributing to the reaction. The partial wave analysis confirms the existence of some nucleon and Δ resonances, for which so far only fair evidence was reported. A large number of decay modes of known nucleon and Δ resonances is presented. It is shown that detailed investigations of decay branching ratios may provide a key to unravelling the structure of nucleon and Δ resonances.

Important role of projectile excitation in 16O+60Ni and 16O+27Al scattering at intermediate energies

NASA Astrophysics Data System (ADS)

Zagatto, V. A. B.; Cappuzzello, F.; Lubian, J.; Cavallaro, M.; Linares, R.; Carbone, D.; Agodi, C.; Foti, A.; Tudisco, S.; Wang, J. S.; Oliveira, J. R. B.; Hussein, M. S.

2018-05-01

The elastic scattering angular distribution of the 16O+60Ni system at 260 MeV was measured in the range of the Rutherford cross section down to seven orders of magnitude. The cross sections of the lowest 2+ and 3- inelastic states of the target were also measured over several orders of magnitude. Coupled-channel (CC) calculations were performed and are shown to be compatible with the whole set of data only when including the excitation of the projectile and when the deformations of the imaginary part of the nuclear optical potential are taken into account. Similar results were obtained when the procedure is applied to the existing data on 16O+27Al elastic and inelastic scattering at 100 and 280 MeV. An analysis in terms of dynamical polarization potentials (DPP) indicates the major role of coupled-channel effects in the overlapping surface region of the colliding nuclei.

Terahertz Imaging of Three-Dimensional Dehydrated Breast Cancer Tumors

NASA Astrophysics Data System (ADS)

Bowman, Tyler; Wu, Yuhao; Gauch, John; Campbell, Lucas K.; El-Shenawee, Magda

2017-06-01

This work presents the application of terahertz imaging to three-dimensional formalin-fixed, paraffin-embedded human breast cancer tumors. The results demonstrate the capability of terahertz for in-depth scanning to produce cross section images without the need to slice the tumor. Samples of tumors excised from women diagnosed with infiltrating ductal carcinoma and lobular carcinoma are investigated using a pulsed terahertz time domain imaging system. A time of flight estimation is used to obtain vertical and horizontal cross section images of tumor tissues embedded in paraffin block. Strong agreement is shown comparing the terahertz images obtained by electronically scanning the tumor in-depth in comparison with histopathology images. The detection of cancer tissue inside the block is found to be accurate to depths over 1 mm. Image processing techniques are applied to provide improved contrast and automation of the obtained terahertz images. In particular, unsharp masking and edge detection methods are found to be most effective for three-dimensional block imaging.

Photoionization of the hydrogen atom in strong magnetic fields

NASA Technical Reports Server (NTRS)

Potekhin, Aleksandr IU.; Pavlov, George G.

1993-01-01

The photoionization of the hydrogen atom in magnetic fields B about 10 exp 11 - 10 exp 13 G typical of the surface layers of neutron stars is investigated analytically and numerically. We consider the photoionization from various tightly bound and hydrogen-like states of the atom for photons with arbitrary polarizations and wave-vector directions. It is shown that the length form of the interaction matrix elements is more appropriate in the adiabatic approximation than the velocity form, at least in the most important frequency range omega much less than omega(B), where omega(B) is the electron cyclotron frequency. Use of the length form yields nonzero cross sections for photon polarizations perpendicular to the magnetic field at omega less than omega(B); these cross sections are the ones that most strongly affect the properties of the radiation escaping from an optically thick medium, e.g., from the atmosphere of a neutron star. The results of the numerical calculations are fitted by simple analytical formulas.

Fast neutron measurements using Cs2LiYCl6:Ce (CLYC) scintillator

NASA Astrophysics Data System (ADS)

Smith, M. B.; Achtzehn, T.; Andrews, H. R.; Clifford, E. T. H.; Forget, P.; Glodo, J.; Hawrami, R.; Ing, H.; O'Dougherty, P.; Shah, K. S.; Shirwadkar, U.; Soundara-Pandian, L.; Tower, J.

2015-06-01

Samples of Cs2LiYCl6:Ce (CLYC) scintillator have been characterized using monoenergetic neutron beams in the energy range 4.1-5.5 MeV. Four crystals with dimensions (thickness×diameter) of 1″×1″, 1″×2″, and 2″×2″ were evaluated, including one crystal with natural concentrations of Li isotopes and three that were enriched in 6Li. The intrinsic efficiency of CLYC for fast-neutron detection has been determined for the natural-Li crystal. These measurements were translated into reaction cross-sections, and show good agreement with available cross-section data for neutron interactions with the 35Cl component of CLYC. Furthermore, it is shown that the charged-particle energy released in the fast-neutron reactions on 35Cl varies linearly with the energy of the incoming neutron. These results verify the efficacy of CLYC for fast-neutron spectroscopy in a range of applications.

One-dimensional analysis of thin-walled beams with diaphragms and its application to optimization for stiffness reinforcement

NASA Astrophysics Data System (ADS)

Jung, Joon Hee; Jang, Gang-Won; Shin, Dongil; Kim, Yoon Young

2018-03-01

This paper presents a method to analyze thin-walled beams with quadrilateral cross sections reinforced with diaphragms using a one-dimensional higher-order beam theory. The effect of a diaphragm is reflected focusing on the increase of static stiffness. The deformations on the beam-interfacing boundary of a thin diaphragm are described by using deformation modes of the beam cross section while the deformations inside the diaphragm are approximated in the form of complete cubic polynomials. By using the principle of minimum potential energy, its stiffness that significantly affects distortional deformation of a thin-walled beam can be considered in the one-dimensional beam analysis. It is shown that the accuracy of the resulting one-dimensional analysis is comparable with that by a shell element based analysis. As a means to demonstrate the usefulness of the present approach for design, position optimization problems of diaphragms for stiffness reinforcement of an automotive side frame are solved.

Dynamics of threading dislocations in porous heteroepitaxial GaN films

NASA Astrophysics Data System (ADS)

Gutkin, M. Yu.; Rzhavtsev, E. A.

2017-12-01

Behavior of threading dislocations in porous heteroepitaxial gallium nitride (GaN) films has been studied using computer simulation by the two-dimensional discrete dislocation dynamics approach. A computational scheme, where pores are modeled as cross sections of cylindrical cavities, elastically interacting with unidirectional parallel edge dislocations, which imitate threading dislocations, is used. Time dependences of coordinates and velocities of each dislocation from dislocation ensembles under investigation are obtained. Visualization of current structure of dislocation ensemble is performed in the form of a location map of dislocations at any time. It has been shown that the density of appearing dislocation structures significantly depends on the ratio of area of a pore cross section to area of the simulation region. In particular, increasing the portion of pores surface on the layer surface up to 2% should lead to about a 1.5-times decrease of the final density of threading dislocations, and increase of this portion up to 15% should lead to approximately a 4.5-times decrease of it.

Experimental and Numerical Study on Performance of Ducted Hydrokinetic Turbines with Pre-Swirl Stator Blades.

NASA Astrophysics Data System (ADS)

Gish, Andrew

2015-11-01

Ducts (also called shrouds) have been shown to improve performance of hydrokinetic turbines in some situations, bringing the power coefficient (Cp) closer to the Betz limit. Here we investigate optimization of the duct design as well as the addition of stator blades upstream of the turbine rotor to introduce pre-swirl in the flow. A small scale three-bladed turbine was tested in a towing tank. Three cases (bare turbine, with duct, and with duct and stators) were tested over a range of flow speeds. Important parameters include duct cross-sectional shape, blade-duct gap, stator cross-sectional shape, and stator angle. For each test, Cp was evaluated as a function of tip speed ratio (TSR). Experimental results were compared with numerical simulations. Results indicate that ducts and stators can improve performance at slower flow speeds and lower the stall speed compared to a bare turbine, but may degrade performance at higher speeds. Ongoing efforts to optimize duct and stator configurations will be discussed.

Comparison of sigma(o) obtained from the conventional definition with sigma(o) appearing in the radar equation for randomly rough surfaces

NASA Technical Reports Server (NTRS)

Levine, D. M.

1981-01-01

A comparison is made of the radar cross section of rough surface calculated in one case from the conventional definition and obtained in the second case directly from the radar equation. The validity of the conventional definition representing the cross section appearing in the radar equation is determined. The analysis is executed in the special case of perfectly conducting, randomly corrugated surfaces in the physical optics limit. The radar equation is obtained by solving for the radiation scattered from an arbitrary source back to a colocated antenna. The signal out of the receiving antenna is computed from this solution and the result put into a form recognizeable as the radar equation. The conventional definition is obtained by solving a similar problem but for backscatter from an incident planewave. It is shown that these tow forms for sigma are the same if the observer is far enough from the surface.

Cross-sectional study on risk factors of HIV among female commercial sex workers in Cambodia.

PubMed Central

Ohshige, K.; Morio, S.; Mizushima, S.; Kitamura, K.; Tajima, K.; Ito, A.; Suyama, A.; Usuku, S.; Saphonn, V.; Heng, S.; Hor, L. B.; Tia, P.; Soda, K.

2000-01-01

To describe epidemiological features on HIV prevalence among female commercial sex workers (CSWs), a cross-sectional study on sexual behaviour and serological prevalence was carried out in Cambodia. The CSWs were interviewed on their demographic characters and behaviour and their blood samples were taken for testing on sexually transmitted diseases, including HIV, Chlamydia trachomatis, syphilis, and hepatitis B. Associations between risk factors and HIV seropositivity were analysed. High seroprevalence of HIV and Chlamydia trachomatis IgG antibody (CT-IgG-Ab) was shown among the CSWs (54 and 81.7%, respectively). Univariate logistic regression analyses showed an association between HIV seropositivity and age, duration of prostitution, the number of clients per day and CT-IgG-Ab. Especially, high-titre chlamydial seropositivity showed a strong significant association with HIV prevalence. In multiple logistic regression analyses, CT-IgG-Ab with higher titre was significantly independently related to HIV infection. These suggest that existence of Chlamydia trachomatis is highly related to HIV prevalence. PMID:10722142

Quantitative hard x-ray phase contrast imaging of micropipes in SiC

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

Kohn, V. G.; Argunova, T. S.; Je, J. H., E-mail: jhje@postech.ac.kr

2013-12-15

Peculiarities of quantitative hard x-ray phase contrast imaging of micropipes in SiC are discussed. The micropipe is assumed as a hollow cylinder with an elliptical cross section. The major and minor diameters can be restored using the least square fitting procedure by comparing the experimental data, i.e. the profile across the micropipe axis, with those calculated based on phase contrast theory. It is shown that one projection image gives an information which does not allow a complete determination of the elliptical cross section, if an orientation of micropipe is not known. Another problem is a weak accuracy in estimating themore » diameters, partly because of using pink synchrotron radiation, which is necessary because a monochromatic beam intensity is not sufficient to reveal the weak contrast from a very small object. The general problems of accuracy in estimating the two diameters using the least square procedure are discussed. Two experimental examples are considered to demonstrate small as well as modest accuracies in estimating the diameters.« less

Set of new observables in the process e+e-→Z H H

NASA Astrophysics Data System (ADS)

Nakamura, Junya

2018-01-01

Consequences of nonstandard Higgs couplings in the final-state distributions of the process e+e-→Z H H are studied. We derive an analytic expression for the differential cross section, which has in the most general case nine nonzero functions. These functions are the coefficients of nine angular terms, depend on the Higgs couplings, and can be experimentally measured as observables. Symmetry properties of these nine functions are carefully discussed, and they are divided into four categories under C P and C P T ˜. The relations between our observables and the observables which exist in the literature are also clarified. We numerically study the dependence of our observables on the parameters in an effective Lagrangian for the Higgs couplings. It is shown that these new observables depend on most of the effective Lagrangian parameters in different ways from the total cross section. A benefit from longitudinally polarized e+e- beams is also discussed.

RCS of ships and aircraft at HF frequencies

NASA Astrophysics Data System (ADS)

Trueman, C. W.; Kubina, S. J.; Mishra, S. R.; Larose, C.

Coastal radar operating at high frequency (HF) has the potential of monitoring iceberg movement and ship and aircraft traffic over a wide area of ocean. The HF radar cross-section of an aircraft-like scatterer of simple geometry is investigated. At these frequencies, the aircraft size is comparable to the wavelength. The aircraft radar cross-section (RCS) is obtained both by computation and by direct measurement. It is demonstrated that at low frequencies in the HF range, the dorsal fin is the dominant scatterer, but at high HF the fuselage can scatter more strongly than the dorsal fin. Aircraft often carry wire antennas for HF communication, and it is shown that such wires can dramatically alter the RCS of the aircraft near the resonant frequencies of the wire. The RCS of a ship modelled as a parallelepiped with mast is 20-30 decibels larger than that of an aircraft, and is dominated at low HF by the contribution of the mast.

Simulations and measurements of a radar cross section of a Boeing 747-200 in the 20-60 MHz frequency band

NASA Astrophysics Data System (ADS)

David, A.; Brousseau, C.; Bourdillon, A.

2003-08-01

HF and VHF low frequency bands provide a promising way to perform radar target recognition. At these frequencies, Radar Cross Section (RCS) behavior is not well known because the scattered field is due to a complex phenomenon where the interactions between the different parts of the structure have a significant contribution, which makes the prediction difficult. A wire model of a commercial Boeing 747-200 aircraft, developed to be used with the Numerical Electromagnetic Code (NEC), is presented. The reliability of this model has been assessed by comparing the results given by NEC with the measurements made in an anechoïc chamber with a scaled aircraft, and a relatively good agreement was observed between simulations and measurements. The RCS variations of an aircraft along different flight routes have been investigated, and it is shown that it is necessary to know the flight route of the airplane to envisage target identification in spite of the use of the low frequency band.

Interpreting sea surface slicks on the basis of the normalized radar cross-section model using RADARSAT-2 copolarization dual-channel SAR images

NASA Astrophysics Data System (ADS)

Ivonin, D. V.; Skrunes, S.; Brekke, C.; Ivanov, A. Yu.

2016-03-01

A simple automatic multipolarization technique for discrimination of main types of thin oil films (of thickness less than the radio wave skin depth) from natural ones is proposed. It is based on a new multipolarization parameter related to the ratio between the damping in the slick of specially normalized resonant and nonresonant signals calculated using the normalized radar cross-section model proposed by Kudryavtsev et al. (2003a). The technique is tested on RADARSAT-2 copolarization (VV/HH) synthetic aperture radar images of slicks of a priori known provenance (mineral oils, e.g., emulsion and crude oil, and plant oil served to model a natural slick) released during annual oil-on-water exercises in the North Sea in 2011 and 2012. It has been shown that the suggested multipolarization parameter gives new capabilities in interpreting slicks visible on synthetic aperture radar images while allowing discrimination between mineral oil and plant oil slicks.

Americium-241 integral radiative capture cross section in over-moderated neutron spectrum from pile oscillator measurements in the Minerve reactor

NASA Astrophysics Data System (ADS)

Geslot, Benoit; Gruel, Adrien; Ros, Paul; Blaise, Patrick; Leconte, Pierre; Noguere, Gilles; Mathieu, Ludovic; Villamarin, David; Becares, Vicente; Plompen, Arjan; Kopecky, Stefan; Schillebeeckx, Peter

2017-09-01

An experimental program, called AMSTRAMGRAM, was recently conducted in the Minerve low power reactor operated by CEA Cadarache within the frame of the CHANDA initiative (Solving CHAllenges in Nuclear Data). Its aim was to measure the integral capture cross section of 241Am in the thermal domain. Motivation of this work is driven by large differences in this actinide thermal point reported by major nuclear data libraries. The AMSTRAMGRAM experiment, that made use of well characterized EC-JRC americium samples, was based on the oscillation technique commonly implemented in the Minerve reactor. First results are presented and discussed in this article. A preliminary calculation scheme was used to compare measured and calculated results. It is shown that this work confirms a bias previously observed with JEFF-3.1.1 (C/E-1 = -10.5 ± 2%). On the opposite, the experiment is in close agreement with 241Am thermal point reported in JEFF-3.2 (C/E-1 = 0.5 ± 2%).

Absolute cross section for loss of supercoiled topology induced by 10 eV electrons in highly uniform /DNA/1,3-diaminopropane films deposited on highly ordered pyrolitic graphite

PubMed Central

Boulanouar, Omar; Fromm, Michel; Bass, Andrew D.; Cloutier, Pierre; Sanche, Léon

2013-01-01

It was recently shown that the affinity of doubly charged, 1–3 diaminopropane (Dap2+) for DNA permits the growth on highly ordered pyrolitic graphite (HOPG) substrates, of plasmid DNA films, of known uniform thickness [O. Boulanouar, A. Khatyr, G. Herlem, F. Palmino, L. Sanche, and M. Fromm, J. Phys. Chem. C 115, 21291–21298 (2011)]. Post-irradiation analysis by electrophoresis of such targets confirms that electron impact at 10 eV produces a maximum in the yield of single strand breaks that can be associated with the formation of a DNA− transient anion. Using a well-adapted deterministic survival model for the variation of electron damage with fluence and film thickness, we have determined an absolute cross section for strand-break damage by 10 eV electrons and inelastic scattering attenuation length in DNA-Dap complex films. PMID:23927289

A simulation-based study on the influence of beam hardening in X-ray computed tomography for dimensional metrology.

PubMed

Lifton, Joseph J; Malcolm, Andrew A; McBride, John W

2015-01-01

X-ray computed tomography (CT) is a radiographic scanning technique for visualising cross-sectional images of an object non-destructively. From these cross-sectional images it is possible to evaluate internal dimensional features of a workpiece which may otherwise be inaccessible to tactile and optical instruments. Beam hardening is a physical process that degrades the quality of CT images and has previously been suggested to influence dimensional measurements. Using a validated simulation tool, the influence of spectrum pre-filtration and beam hardening correction are evaluated for internal and external dimensional measurements. Beam hardening is shown to influence internal and external dimensions in opposition, and to have a greater influence on outer dimensions compared to inner dimensions. The results suggest the combination of spectrum pre-filtration and a local gradient-based surface determination method are able to greatly reduce the influence of beam hardening in X-ray CT for dimensional metrology.

Averaging cross section data so we can fit it

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

Brown, D.

2014-10-23

The 56Fe cross section we are interested in have a lot of fluctuations. We would like to fit the average of the cross section with cross sections calculated within EMPIRE. EMPIRE is a Hauser-Feshbach theory based nuclear reaction code, requires cross sections to be smoothed using a Lorentzian profile. The plan is to fit EMPIRE to these cross sections in the fast region (say above 500 keV).

New cross sections for H on H2 collisional transitions

NASA Astrophysics Data System (ADS)

Zou, Qianxia

2011-12-01

The cross section for H on H2 collisions is important for astrophysics as well as our understanding of the simple chemical systems. This is the simplest atom-molecule cross section. With a new H3 potential surface by Mielke et al., we have modified the ABC code by Skouteris, Castillo and Manolopoulos to calculate new cross sections. These cross sections are compared to previous cross section calculations.

A computer program for analyzing channel geometry

USGS Publications Warehouse

Regan, R.S.; Schaffranek, R.W.

1985-01-01

The Channel Geometry Analysis Program (CGAP) provides the capability to process, analyze, and format cross-sectional data for input to flow/transport simulation models or other computational programs. CGAP allows for a variety of cross-sectional data input formats through use of variable format specification. The program accepts data from various computer media and provides for modification of machine-stored parameter values. CGAP has been devised to provide a rapid and efficient means of computing and analyzing the physical properties of an open-channel reach defined by a sequence of cross sections. CGAP 's 16 options provide a wide range of methods by which to analyze and depict a channel reach and its individual cross-sectional properties. The primary function of the program is to compute the area, width, wetted perimeter, and hydraulic radius of cross sections at successive increments of water surface elevation (stage) from data that consist of coordinate pairs of cross-channel distances and land surface or channel bottom elevations. Longitudinal rates-of-change of cross-sectional properties are also computed, as are the mean properties of a channel reach. Output products include tabular lists of cross-sectional area, channel width, wetted perimeter, hydraulic radius, average depth, and cross-sectional symmetry computed as functions of stage; plots of cross sections; plots of cross-sectional area and (or) channel width as functions of stage; tabular lists of cross-sectional area and channel width computed as functions of stage for subdivisions of a cross section; plots of cross sections in isometric projection; and plots of cross-sectional area at a fixed stage as a function of longitudinal distance along an open-channel reach. A Command Procedure Language program and Job Control Language procedure exist to facilitate program execution on the U.S. Geological Survey Prime and Amdahl computer systems respectively. (Lantz-PTT)

Multistrand superconductor cable

DOEpatents

Borden, A.R.

1984-03-08

Improved multistrand Rutherford-type superconductor cable is produced by using strands which are preformed, prior to being wound into the cable, so that each strand has a variable cross section, with successive portions having a substantially round cross section, a transitional oval cross section, a rectangular cross section, a transitional oval cross section, a round cross section and so forth, in repetitive cycles along the length of the strand. The cable is wound and flattened so that the portions of rectangular cross section extend across the two flat sides of the cable at the strand angle. The portions of round cross section are bent at the edges of the flattened cable, so as to extend between the two flat sides. The rectangular portions of the strands slide easil

Strength Calculation of Inclined Sections of Reinforced Concrete Elements under Transverse Bending

NASA Astrophysics Data System (ADS)

Filatov, V. B.

2017-11-01

The authors propose a design model to determine the strength of inclined sections of bent reinforced concrete elements without shear reinforcement for the action of transverse force taking into account the aggregate interlock forces in the inclined crack. The calculated dependences to find out the components of forces acting in an inclined section are presented. The calculated dependences are obtained from the consideration of equilibrium conditions of the block over the inclined crack. A comparative analysis of the experimental values of the failure loads of the inclined section and the theoretical values obtained for the proposed dependencies and normative calculation methods is performed. It is shown that the proposed design model makes it possible to take into account the effect the longitudinal reinforcement percentage has on the inclined section strength, the element cross section height without the introduction of empirical coefficients which contributes to an increase in the structural safety of design solutions including the safety of high-strength concrete elements.

Non-traditional shape GFRP rebars for concrete reinforcement

NASA Astrophysics Data System (ADS)

Claure, Guillermo G.

The use of glass-fiber-reinforced-polymer (GFRP) composites as internal reinforcement (rebars) for concrete structures has proven to be an alternative to traditional steel reinforcement due to significant advantages such as magnetic transparency and, most importantly, corrosion resistance equating to durability and structural life extension. In recent years, the number of projects specifying GFRP reinforcement has increased dramatically leading the construction industry towards more sustainable practices. Typically, GFRP rebars are similar to their steel counterparts having external deformations or surface enhancements designed to develop bond to concrete, as well as having solid circular cross-sections; but lately, the worldwide composites industry has taken advantage of the pultrusion process developing GFRP rebars with non-traditional cross-sectional shapes destined to optimize their mechanical, physical, and environmental attributes. Recently, circular GFRP rebars with a hollow-core have also become available. They offer advantages such as a larger surface area for improved bond, and the use of the effective cross-sectional area that is engaged to carry load since fibers at the center of a solid cross-section are generally not fully engaged. For a complete understanding of GFRP rebar physical properties, a study on material characterization regarding a quantitative cross-sectional area analysis of different GFRP rebars was undertaken with a sample population of 190 GFRP specimens with rebar denomination ranging from #2 to #6 and with different cross-sectional shapes and surface deformations manufactured by five pultruders from around the world. The water displacement method was applied as a feasible and reliable way to conduct the investigation. In addition to developing a repeatable protocol for measuring cross-sectional area, the objectives of establishing critical statistical information related to the test methodology and recommending improvements to existing provisions and standards allowing for a consistent universal norm for all GFRP rebars were reached. This dissertation also presents an evaluation of the structural behavior of reinforced concrete (RC) beams and slabs using the new type of GFRP rebar consisting of a non-traditional hollow-core shape compared to "traditional" solid round rebars with equivalent cross-sectional areas within the framework of two studies, respectively. To validate the design assumptions following ACI 440.1R design guidelines, two conditions were investigated: under-reinforced (failure controlled by rupture of GFRP rebar); and, over-reinforced (failure controlled by crushing of concrete). For comparison, a cyclic three-point bending load test matrix was developed: for beams, 3 under-reinforced and 3 over-reinforced with hollow-core and solid GFRP rebars, respectively, making a total of 12 RC specimens; for slabs, 3 under-reinforced and 3 over-reinforced with hollow-core and 2 types of solid GFRP rebars, respectively, making a total of 18 RC slabs. The studies on GFRP RC beams and slabs concluded that the hollow-core GFRP rebars were as effective as their solid counterpart and ACI 440.1R design guidelines were applicable to predict their performance. It was shown that final design may be controlled by the permissible deflections as governing parameter for elements under service conditions. Also, a final study with a test matrix containing six extra specimens was generated for post-fire residual strength evaluation of fire-exposed GFRP RC slabs along with temperature gradient in the slabs and dynamic mechanical analysis (DMA) investigation on GFRP samples extracted from the fire-exposed slabs. In this study, the ability of GFRP RC slabs to retain structural integrity during a standards fire exposure as well as determining the residual structural capacity were investigated. The residual strength evaluation of the fire-exposed slabs showed a range of results varying between +/- 10%, of the virgin slabs. And, 19 mm (0.75 in.) cover with normal weight concrete was shown to be adequate to provide the necessary fire protection to the GFRP rebars preventing irreversible damage for two-hour fire rated GFRP RC slabs subjected to service loads; also, from the DMA and glass transition temperature of samples extracted from the GFRP rebars, it is inferred that the resin had undergone a post curing phase.

Ion dipole capture cross sections at low ion and rotational energies - Comparison of integrated capture cross sections with reaction cross sections for NH3 and H2O parent-ion collisions.

NASA Technical Reports Server (NTRS)

Dugan, J. V., Jr.; Canright, R. B., Jr.

1972-01-01

The numerical capture cross section is calculated from the capture ratio, defined as the fraction of trajectories reaching a prescribed minimum separation of 3 A. The calculated capture cross sections for a rotational temperature of 77 K suggest large reaction cross sections in 80 K experiments for the large dipole-moment target, methyl cyanide.

Sex- and age-related differences in mid-thigh composition and muscle quality determined by computed tomography in middle-aged and elderly Japanese.

PubMed

Kasai, Takehiro; Ishiguro, Naoki; Matsui, Yasumoto; Harada, Atsushi; Takemura, Marie; Yuki, Atsumu; Kato, Yuki; Otsuka, Rei; Ando, Fujiko; Shimokata, Hiroshi

2015-06-01

Sex- and age-related differences in mid-thigh composition and muscle quality remain unclear. The present study aimed to clarify these differences using computed tomography in middle-aged and elderly Japanese. A total of 2310 participants (age 40-89 years), who were randomly selected from the local residents, underwent computed tomography examination of the right mid-thigh. Thigh circumference and cross-sectional areas of the thigh, muscle, quadriceps, non-quadriceps, fat, and bone were measured. Knee extension strength and muscle quality index (knee extension strength/quadriceps cross-sectional area) were also assessed. Sex- and age-related differences in these indices were analyzed. The thigh cross-sectional area in men and women decreased by 0.6% and 0.5%/year, respectively, because of a decrease in muscle cross-sectional area (men 75.2%, women 40.6%), fat cross-sectional area (men 24.4%, women 59.6%) and bone cross-sectional area (men 0.5%, women -0.2%). Muscle cross-sectional area in men and women decreased by 0.6% and 0.4%/year, respectively, because of a decrease in quadriceps cross-sectional area (men 65.6%, women 81.6%) and non-quadriceps cross-sectional area (men 34.4%, women 18.4%). Muscle quality in men and women decreased by 0.4% and 0.3%/year, respectively. Thigh cross-sectional area decreased with age mainly because of a decrease in muscle cross-sectional area in men and fat cross-sectional area in women. The rate of decrease in muscle cross-sectional area was 1.5-fold higher in men than in women. Muscle cross-sectional area decreased with age mainly because of a decrease in quadriceps cross-sectional area, especially in women. Decrease in muscle quality with age was similar in both sexes. © 2014 Japan Geriatrics Society.

Theoretical study of corrugated plates: Shearing of a trapezoidally corrugated plate with trough lines permitted to curve

NASA Technical Reports Server (NTRS)

Lin, C.; Libove, C.

1971-01-01

A theoretical analysis is presented of the elastic shearing of a trapezoidally corrugated plate with discrete attachments at the ends of the corrugations. Numerical results on effective shear stiffness, stresses, and displacements are presented for selected geometries and end-attachment conditions. It is shown that the frame-like deformation of the cross-sections, which results from the absence of continuous end attachments, can lead to large transverse bending stresses and large reductions in shearing stiffness.

Metastability in the formation of Condon domains

NASA Astrophysics Data System (ADS)

Bakaleinikov, L. A.; Gordon, A.

2018-05-01

Metastability effects in the formation of Condon non-spin magnetic domains are considered. A possibility for the first-order phase transition occurrence in a three-dimensional electron gas is described in the case of two-frequency de-Haas-van Alphen magnetization oscillations originating from two extremal cross sections of the Fermi surface. The appearance of two additional domains is shown in the metastable region in aluminum. The phase diagram temperature-magnetic field exhibits the presence of second-order and first- order phase transitions in the two-frequency case.

Heat treatment effect on the mechanical properties of industrial drawn copper wires

NASA Astrophysics Data System (ADS)

Beribeche, Abdellatif; Boumerzoug, Zakaria; Ji, Vincent

2013-12-01

In this present investigation, the mechanical properties of industrial drawn copper wires have been studied by tensile tests. The effect of prior heat treatments at 500°C on the drawn wires behavior was the main goal of this investigation. We have found that the mechanical behavior of drawn wires depends strongly on those treatments. SEM observations of the wire cross section after tensile tests have shown that the mechanism of rupture was mainly controlled by the void formation.

Radar characteristics of cloud-to-ground lightning producing storms in Florida

NASA Technical Reports Server (NTRS)

Buechler, D. E.; Goodman, S. J.

1991-01-01

The interrelation between cloud-to-ground lightning, convective rainfall, and the environment in Central Florida storms is examined. The rain flux, storm area, and ground discharge rates are computed within the outlined area. Time-height cross sections of maximum dBZ values at each level for two storms are shown. The multicellular nature of these storms is readily apparent. The cloud-to-ground lightning activity occurs mainly where high reflectivity values (30-40 dBZ) extend above 7 km.

Optimization of the operating conditions of fuel oil combustion in the furnaces of large-capacity boilers

NASA Astrophysics Data System (ADS)

Zroichikov, N. A.; Lyskov, M. G.; Prokhorov, V. B.; Morozova, E. A.

2007-06-01

We describe a proposed small-size cavitator having an adjustable flow cross-section, which allows the dispersion of water-fuel oil emulsion to be varied during the operation of large-capacity boilers. It is shown that the operating conditions of the boiler must be synchronized with those of the cavitator if we wish the problem of reducing the amount of harmful substances emitted into the atmosphere during the combustion of fuel oil to be solved in a comprehensive manner.

The Adf Insurgency Network in the Eastern Democratic Republic of the Congo: Spillover Effects Into Tanzania

DTIC Science & Technology

2014-06-01

beginning of the end for his regime. To continue stay in power, Mobutu had to do something. He opted for a laissez - faire style of leadership . He allowed... leadership , run away with weapons, started a fresh fight against government forces and launched violence against unarmed civilians. Unless M23 is...fighters.51 However, the organizational structure shown in Figure 4 represents only a cross-section of ADF leadership consisting of 17 members.52

Laser Doppler measurements of laminar and turbulent flow in a pipe bend

NASA Technical Reports Server (NTRS)

Enayet, M. M.; Gibson, M. M.; Taylor, A. M. K. P.; Yianneskis, M.

1982-01-01

The streamwise components of velocity in the flow through a ninety degree bend of circular cross section for which the ratio of radius of curvature to diameter is 2.8 were measured. The development of strong pressure driven secondary flow in the form of a pair of counter rotating vortices in the steamwise direction is shown. Refractive index matching at the fluid wall interface was not employed; the displacement of the measurement volume due to refraction is allowed for in simple geometrical calculations.

Failure Analysis of a CH-47 Horizontal Hinge Pin Assembly, P/N 114RS226

DTIC Science & Technology

2006-12-01

and globular) dispersed in a matrix of tempered martensite observed in all the metallographic cross sections produced from the M50 steel rings and...ring, were shown to have met the requirements of AMS 6491 (1)—the specification for VIM- VAR M50 required by each roller- bearing set drawing (see table...2). Although the phosphorus content for each part was at or near the maximum level allowed by AMS 6491, literature on M50 steel and a conversation

Proceedings of the Special Meeting on the Physics of Detectors Held at U.S. Naval Training Device Center, Orlando, Florida, on 15 March 1972

DTIC Science & Technology

1972-08-01

manufacture. The bias is well within the power rating of the device. -le havo also seer. similar noise in lead- sulphide detectors. The noiie shown xeseibles...University Syracuse, New York ABSTRACT (Unclassified) The recombination cross section for mercury -doped germanium has been measured between 4-40 K, irt...in the mercury -doped samples was accounted for by quantitatively determining the density of these centers from carrier concentration and mobility

Deuterated scintillators and their application to neutron spectroscopy

NASA Astrophysics Data System (ADS)

Febbraro, M.; Lawrence, C. C.; Zhu, H.; Pierson, B.; Torres-Isea, R. O.; Becchetti, F. D.; Kolata, J. J.; Riggins, J.

2015-06-01

Deuterated scintillators have been used as a tool for neutron spectroscopy without Neutron Time-of-Flight (n-ToF) for more than 30 years. This article will provide a brief historical overview of the technique and current uses of deuterated scintillators in the UM-DSA and DESCANT arrays. Pulse-shape discrimination and spectrum unfolding with the maximum-likelihood expectation maximization algorithm will be discussed. Experimental unfolding and cross section results from measurements of (d,n), (3He,n) and (α,n) reactions are shown.

Quasi-Optical Techniques for Millimeter and Submillimeter-Wave Circuits.

DTIC Science & Technology

1981-03-25

permits non-destructive measurement. The cross section of the IS guide is shown in Fig. 4. We create a notch -type grating in the dielectric strip (rl). Then...the e-igenvalue equation is solved. 1he method was modified to minAlyze .a circular patch radiatlng st ructulre. l’ht, prote dtlrc i s essentIalIv...34Hankel transform domain analysis of open circular microstrip radiating structures," IEEE Trans. Antennas and Propagation, Vol. AP-29, Jan. 1981. 19. T

Investigation of the Acoustics of Marine Sediments Using an Impedance Tube and Continued Investigation of the Acoustics of Marine Sediments Using Impedance Tube and Acoustic Resonator Techniques

DTIC Science & Technology

2010-08-02

properties of three gulf-coast species, Thalassia testudinum (turtle grass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal... Thalassia testudinum (turtle grass) is shown in Fig. 12. The two curves show plant volume fraction Vleaves/Vlot (measured by acoustic and image-based...cross-section image analysis (Fig. 13), was found to be X\\<*t = 0.23. Similar results were found the Thalassia testudinum (turtle grass) rhizomes

Treemap Visualization for Space Situational Awareness

DTIC Science & Technology

2015-10-18

virtually any display like a table with textual metadata, a hyperlink to a web page, or another treemap. Animation can be used to “explode” the tile to...release; distribution unlimited. 88ABW Cleared 07/30/2015; 88ABW-2015-3828. In Fig. 7 shown below, we have chosen to select “Size By Radar Cross...Section ( RCS )”. We’re still looking at the same Unclassified Space Catalog scenario, but we’ve simply chosen a different “Size by” option, and the view

Charm production in deep inelastic muon-iron interactions at 200 GeV/c

NASA Astrophysics Data System (ADS)

Arneodo, M.; Aubert, J. J.; Bassompierre, G.; Becks, K. H.; Benchouk, C.; Best, C.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Broll, C.; Brown, S. C.; Carr, J.; Clifft, R.; Cobb, J. H.; Coignet, G.; Combley, F.; Court, G. R.; D'Agostini, G.; Dau, W. D.; Davies, J. K.; Declais, Y.; Dosselli, U.; Drees, J.; Edwards, A.; Edwards, M.; Favier, J.; Ferrero, M. I.; Flauger, W.; Forsbach, H.; Gabathuler, E.; Gamet, R.; Gayler, J.; Gerhardt, V.; Gössling, C.; Haas, J.; Hamacher, K.; Hayman, P.; Henckes, M.; Korbel, V.; Landgraf, U.; Leenen, M.; Maire, M.; Maselli, S.; Mohr, W.; Montgomery, H. E.; Moser, K.; Mount, R. P.; Nagy, E.; Nassalski, J.; Norton, P. R.; McNicholas, J.; Osborne, A. M.; Payre, P.; Peroni, C.; Pessard, H.; Pietrzyk, U.; Rith, K.; Schneegans, M.; Sloan, T.; Stier, H. E.; Stockhausen, W.; Thénard, J. M.; Thompson, J. C.; Urban, L.; Wahlen, H.; Whalley, M.; Williams, D.; Williams, W. S. C.; Williamson, J.; Wimpenny, S. J.

1987-03-01

Dimuon and trimuon events have been studied in deep inelastic muon scattering on an iron target at an incident muon energy of 200 GeV. The events are shown to originate mainly from charm production. Comparison of the measured cross sections with data taken at higher muon energies shows that charm production originates predominantly from transverse virtual photons. Within the framework of the photon gluon fusion model this indicates that the parity of the gluon is odd.

Comparisons of Force Measurement Methods for DBD Plasma Actuators in Quiescent Air

NASA Technical Reports Server (NTRS)

Hoskinson, Alan R.; Hershkowitz, Noah; Ashpis, David E.

2009-01-01

We have performed measurements of the force induced by both single (one electrode insulated) and double (both electrodes insulated) dielectric barrier discharge plasma actuators in quiescent air. We have shown that, for single barrier actuators with cylindrical exposed electrodes, as the electrode diameter decrease the force efficiencies increase much faster than a previously reported linear trend. This behavior has been experimentally verified using two different measurement techniques: stagnation probe measurements of the induced flow velocity and direct measurement of the force using an electronic balance. Actuators with rectangular cross-section exposed electrodes do not show the same rapid increase at small thicknesses. We have also shown that the induced force is independent of the material used for the exposed electrode. The same techniques have shown that the induced force of a double barrier actuator increases with decreasing narrow electrode diameter.

Theoretical analysis of heat flow in horizontal ribbon growth from a melt. [silicon metal

NASA Technical Reports Server (NTRS)

Zoutendyk, J. A.

1978-01-01

A theoretical heat flow analysis for horizontalribbon growth is presented. Equations are derived relating pull speed, ribbon thickness, thermal gradient in the melt, and melt temperature for limiting cases of heat removal by radiation only and isothermal heat removal from the solid surface over the melt. Geometrical cross sections of the growth zone are shown to be triangular and nearly parabolic for the two respective cases. Theoretical pull speed for silicon ribbon 0.01 cm thick, where the loss of latent heat of fusion is by radiation to ambient temperature (300 K) only, is shown to be 1 cm/sec for horizontal growth extending 2 cm over the melt and with no heat conduction either to or from the melt. Further enhancement of ribbon growth rate by placing cooling blocks adjacent to the top surface is shown to be theoretically possible.

Total cross sections for positrons scattered elastically from helium based on new measurements of total ionization cross sections

NASA Technical Reports Server (NTRS)

Diana, L. M.; Chaplin, R. L.; Brooks, D. L.; Adams, J. T.; Reyna, L. K.

1990-01-01

An improved technique is presented for employing the 2.3m spectrometer to measure total ionization cross sections, Q sub ion, for positrons incident on He. The new ionization cross section agree with the values reported earlier. Estimates are also presented of total elastic scattering cross section, Q sub el, obtained by subtracting from total scattering cross sections, Q sub tot, reported in the literature, the Q sub ion and Q sub Ps (total positronium formation cross sections) and total excitation cross sections, Q sub ex, published by another researcher. The Q sub ion and Q sub el measured with the 3m high resolution time-of-flight spectrometer for 54.9eV positrons are in accord with the results from the 2.3m spectrometer. The ionization cross sections are in fair agreement with theory tending for the most part to be higher, especially at 76.3 and 88.5eV. The elastic cross section agree quite well with theory to the vicinity of 50eV, but at 60eV and above the experimental elastic cross sections climb to and remain at about 0.30 pi a sub o sq while the theoretical values steadily decrease.

Nano-fabricated plasmonic optical transformer

DOEpatents

Choo, Hyuck; Cabrini, Stefano; Schuck, P. James; Liang, Xiaogan; Yablonovitch, Eli

2015-06-09

The present invention provides a plasmonic optical transformer to produce a highly focuses optical beam spot, where the transformer includes a first metal layer, a dielectric layer formed on the first metal layer, and a second metal layer formed on the dielectric layer, where the first metal layer, the dielectric layer, and the second layer are patterned to a shape including a first section having a first cross section, a second section following the first section having a cross-section tapering from the first section to a smaller cross-section, and a third section following the second section having a cross-section matching the tapered smaller cross-section of the second section.

Multistrand superconductor cable

DOEpatents

Borden, Albert R.

1985-01-01

Improved multistrand Rutherford-type superconductor cable is produced by using strands which are preformed, prior to being wound into the cable, so that each strand has a variable cross section, with successive portions having a substantially round cross section, a transitional oval cross section, a rectangular cross section, a transitional oval cross section, a round cross section and so forth, in repetitive cycles along the length of the strand. The cable is wound and flattened so that the portions of rectangular cross section extend across the two flat sides of the cable at the strand angle. The portions of round cross section are bent at the edges of the flattened cable, so as to extend between the two flat sides. The rectangular portions of the strands slide easily over one another, so as to facilitate flexing and bending of the cable, while also minimizing the possibility of causing damage to the strands by such flexing or bending. Moreover, the improved cable substantially maintains its compactness and cross-sectional shape when the cable is flexed or bent.

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

Szczurek, Antoni; University of Rzeszów; Cisek, Anna

We discuss production of four jets pp → jjjjX with at least two jets with large rapidity separation in proton-proton collisions at the LHC through the mechanism of double-parton scattering (DPS). The cross section is calculated in a factorizaed approximation. Each hard subprocess is calculated in LO collinear approximation. The LO pQCD calculations are shown to give a reasonably good descritption of CMS and ATLAS data on inclusive jet production. It is shown that relative contribution of DPS is growing with increasing rapidity distance between the most remote jets, center-of-mass energy and with decreasing (mini)jet transverse momenta. We show alsomore » result for angular azimuthal dijet correlations calculated in the framework of k{sub t} -factorization approximation.« less

Numerical study of turbulent secondary flows in curved ducts

NASA Technical Reports Server (NTRS)

Hur, N.; Thangam, S.; Speziale, C. G.

1989-01-01

The pressure driven, fully-developed turbulent flow of an incompressible viscous fluid in curved ducts of square cross-section is studied numerically by making use of a finite volume method. A nonlinear Kappa - Iota model is used to represent the turbulence. The results for both straight and curved ducts are presented. For the case of fully-developed turbulent flow in straight ducts, the secondary flow is characterized by an eight-vortex structure for which the computed flowfield is shown to be in good agreement with available experimental data. The introduction of moderate curvature is shown to cause a substantial increase in the strength of the secondary flow and to change the secondary flow pattern to either a double-vortex or a four-vortex configuration.

AMPX: a modular code system for generating coupled multigroup neutron-gamma libraries from ENDF/B

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

Greene, N.M.; Lucius, J.L.; Petrie, L.M.

1976-03-01

AMPX is a modular system for producing coupled multigroup neutron-gamma cross section sets. Basic neutron and gamma cross-section data for AMPX are obtained from ENDF/B libraries. Most commonly used operations required to generate and collapse multigroup cross-section sets are provided in the system. AMPX is flexibly dimensioned; neutron group structures, and gamma group structures, and expansion orders to represent anisotropic processes are all arbitrary and limited only by available computer core and budget. The basic processes provided will (1) generate multigroup neutron cross sections; (2) generate multigroup gamma cross sections; (3) generate gamma yields for gamma-producing neutron interactions; (4) combinemore » neutron cross sections, gamma cross sections, and gamma yields into final ''coupled sets''; (5) perform one-dimensional discrete ordinates transport or diffusion theory calculations for neutrons and gammas and, on option, collapse the cross sections to a broad-group structure, using the one-dimensional results as weighting functions; (6) plot cross sections, on option, to facilitate the ''evaluation'' of a particular multigroup set of data; (7) update and maintain multigroup cross section libraries in such a manner as to make it not only easy to combine new data with previously processed data but also to do it in a single pass on the computer; and (8) output multigroup cross sections in convenient formats for other codes. (auth)« less

Considerations about projectile and target X-rays induced during heavy ion bombardment

NASA Astrophysics Data System (ADS)

Fernandes, F.; Bauer, D. V.; Duarte, A.; Ferrari, T. M.; Niekraszewicz, L. A. B.; Amaral, L.; Dias, J. F.

2018-02-01

In this work we present some results concerning the X-rays emitted by heavy ions during target bombardment. In this case, Cl4+ and Cl5+ ions with energies from 4 MeV to 10 MeV were employed to irradiate vitreous carbon planchets. Moreover, total X-ray production cross sections of titanium X-rays induced by chlorine ions were obtained as well for the same energy range. Only inner shell transitions were considered in the present work. The titanium target consisted of a thin film deposited over vitreous carbon planchets. The results indicate that the projectile X-ray yields increase as a function of the bombarding energy for the present energy range. Effects due to projectile charge state appears to be of minor importance at these low ion velocities. It is shown that a simple exponential function can represent the continuum background of such complex spectra. The chlorine transition rates Kβ/Kα obtained from chlorine acting as a projectile interacting with a carbon target are about half the value when compared to the chlorine Kβ/Kα ratios obtained when a LiCl target is bombarded with C+ and C3+ ions with energies from 2 MeV to 6 MeV. As far as the total X-ray production cross sections of Ti induced by chlorine ions are concerned, the ECPSSR theory underestimates the Ti total X-rays production cross sections by several orders of magnitude. The role of electron capture and possible mechanisms responsible for these effects are discussed.

Bone strength in pure bending: bearing of geometric and material properties.

PubMed

Winter, Werner

2008-01-01

Osteoporosis is characterized by decreasing of bone mass and bone strength with advanced age. For characterization of material properties of dense and cellular bone the volumetric bone mineral density (vBMD) is one of the most important contributing factors to bone strength. Often bending tests of whole bone are used to get information about the state of osteoporosis. In a first step, different types of cellular structures are considered to characterize vBMD and its influence to elastic and plastic material properties. Afterwards, the classical theory of plastic bending is used to describe the non-linear moment-curvature relation of a whole bone. For bending of whole bone with sandwich structure an effective second moment of area can be defined. The shape factor as a pure geometrical value is considered to define bone strength. This factor is discussed for a bone with circular cross section and different thickness of cortical bone. The deduced relations and the decrease of material properties are used to demonstrate the influence of osteoporosis to bone bending strength. It can be shown that the elastic and plastic material properties of bone are related to a relative bone mineral density. Starting from an elastic-plastic bone behavior with an constant yield stress the non-linear moment-curvature relation in bending is related to yielding of the fibres in the cross section. The ultimate moment is characterized by a shape factor depending on the geometry of the cross section and on the change of cortical thickness.

Benchmark experiment for the cross section of the 100Mo(p,2n)99mTc and 100Mo(p,pn)99Mo reactions

NASA Astrophysics Data System (ADS)

Takács, S.; Ditrói, F.; Aikawa, M.; Haba, H.; Otuka, N.

2016-05-01

As nuclear medicine community has shown an increasing interest in accelerator produced 99mTc radionuclide, the possible alternative direct production routes for producing 99mTc were investigated intensively. One of these accelerator production routes is based on the 100Mo(p,2n)99mTc reaction. The cross section of this nuclear reaction was studied by several laboratories earlier but the available data-sets are not in good agreement. For large scale accelerator production of 99mTc based on the 100Mo(p,2n)99mTc reaction, a well-defined excitation function is required to optimise the production process effectively. One of our recent publications pointed out that most of the available experimental excitation functions for the 100Mo(p,2n)99mTc reaction have the same general shape while their amplitudes are different. To confirm the proper amplitude of the excitation function, results of three independent experiments were presented (Takács et al., 2015). In this work we present results of a thick target count rate measurement of the Eγ = 140.5 keV gamma-line from molybdenum irradiated by Ep = 17.9 MeV proton beam, as an integral benchmark experiment, to prove the cross section data reported for the 100Mo(p,2n)99mTc and 100Mo(p,pn)99Mo reactions in Takács et al. (2015).

On limitations of laser-induced fluorescence diagnostics for xenon ion velocity distribution function measurements in Hall thrusters

NASA Astrophysics Data System (ADS)

Romadanov, I.; Raitses, Y.; Diallo, A.; Hara, K.; Kaganovich, I. D.; Smolyakov, A.

2018-03-01

Hall thruster operation is characterized by strong breathing oscillations of the discharge current, the plasma density, the temperature, and the electric field. Probe- and laser-induced fluorescence (LIF) diagnostics were used to measure temporal variations of plasma parameters and the xenon ion velocity distribution function (IVDF) in the near-field plasma plume in regimes with moderate (<18%) external modulations of applied DC discharge voltage at the frequency of the breathing mode. It was shown that the LIF signal collapses while the ion density at the same location is finite. The proposed explanation for this surprising result is based on a strong dependence of the excitation cross-section of metastables on the electron temperature. For large amplitudes of oscillations, the electron temperature at the minimum enters the region of very low cross-section (for the excitation of the xenon ions); thus, significantly reducing the production of metastable ions. Because the residence time of ions in the channel is generally shorter than the time scale of breathing oscillations, the density of the excited ions outside the thruster is low and they cannot be detected. In the range of temperature of oscillations, the ionization cross-section of xenon atoms remains sufficiently large to sustain the discharge. This finding suggests that the commonly used LIF diagnostic of xenon IVDF can be subject to large uncertainties in the regimes with significant oscillations of the electron temperature, or other plasma parameters.

Two-photon luminescence from polar bis-terpyridyl-stilbene derivatives of Ir(III) and Ru(II).

PubMed

Natrajan, Louise S; Toulmin, Anita; Chew, Alex; Magennis, Steven W

2010-12-07

Four structurally related iridium(III) and ruthenium(II) complexes bearing two polar terpyridyl-stilbene derived chromophores 4-(4-{2-[4-(methoxy)phenyl]ethenyl}phenyl)-2,2'-6',2''-terpyridine (ttpyeneanisole) and 4-(4-{2-[phenyl]ethenyl}phenyl)-2,2'-6',2''-terpyridine (tpystilbene) have been synthesised and characterised in the solid state and in solution. In the solid state, the dihedral angle subtending the pyridyl and tolyl groups of 27.1° in the Ir(III) complex [Ir(ttpyeneanisole)(2)]·3PF(6) is more acute than in the Ru(II) derivative [Ru(tpystilbene)(2)]·2PF(6) (35.5°), indicating the presence of a greater degree of π-delocalisation across the terpyridine unit in the former compound. Their luminescence properties in fluid solution have been investigated following both resonant and non-resonant excitation. We have shown that each of the complexes undergoes two-photon excitation when excited in the near infrared (740 to 820 nm), with two-photon absorption cross sections in the range 11-67 × 10(-50) cm(4) s photon(-1). The larger cross sections for the Ir(III) complexes reflect the differences observed in the solid state. This work therefore demonstrates that such complexes are promising as luminescent markers for 3D imaging and illustrates that simple functionalisation of the chromophores and the choice of metal can lead to marked enhancements in the two-photon cross sections (σ(2)) compared to those of simpler heteroleptic polypyridyl based derivatives.

Trunk Muscle Size and Composition Assessment in Older Adults with Chronic Low Back Pain: An Intra-Examiner and Inter-Examiner Reliability Study.

PubMed

Sions, Jaclyn Megan; Smith, Andrew Craig; Hicks, Gregory Evan; Elliott, James Matthew

2016-08-01

To evaluate intra- and inter-examiner reliability for the assessment of relative cross-sectional area, muscle-to-fat infiltration indices, and relative muscle cross-sectional area, i.e., total cross-sectional area minus intramuscular fat, from T1-weighted magnetic resonance images obtained in older adults with chronic low back pain. Reliability study. n = 13 (69.3 ± 8.2 years old) After lumbar magnetic resonance imaging, two examiners produced relative cross-sectional area measurements of multifidi, erector spinae, psoas, and quadratus lumborum by tracing regions of interest just inside fascial borders. Pixel-intensity summaries were used to determine muscle-to-fat infiltration indices; relative muscle cross-sectional area was calculated. Intraclass correlation coefficients were used to estimate intra- and inter-examiner reliability; standard error of measurement was calculated. Intra-examiner intraclass correlation coefficient point estimates for relative cross-sectional area, muscle-to-fat infiltration indices, and relative muscle cross-sectional area were excellent for multifidi and erector spinae across levels L2-L5 (ICC = 0.77-0.99). At L3, intra-examiner reliability was excellent for relative cross-sectional area, muscle-to-fat infiltration indices, and relative muscle cross-sectional area for both psoas and quadratus lumborum (ICC = 0.81-0.99). Inter-examiner intraclass correlation coefficients ranged from poor to excellent for relative cross-sectional area, muscle-to-fat infiltration indices, and relative muscle cross-sectional area. Assessment of relative cross-sectional area, muscle-to-fat infiltration indices, and relative muscle cross-sectional area in older adults with chronic low back pain can be reliably determined by one examiner from T1-weighted images. Such assessments provide valuable information, as muscle-to-fat infiltration indices and relative muscle cross-sectional area indicate that a substantial amount of relative cross-sectional area may be magnetic resonance-visible intramuscular fat in older adults with chronic low back pain. © 2015 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Scala tympani measurement.

PubMed

Walby, A P

1985-01-01

The length and cross-sectional height of the scala tympani are relevant to the design of cochlear implants. The lengths and heights of the scalae tympani in ten pairs of serially sectioned temporal bones were measured by an adaptation of the serial section method of cochlear reconstruction. The study found the middle segments of individual pairs of scalae tympani to be very similar in height, but each pair varied slightly from other pairs. The height decreased overall from the base to the apex, but there was a small expansion at the junction of the basal and middle turns where the interscalar septum originated. The theoretical relationships of different diameter electrodes to the organ of Corti were plotted for one cochlea. The size of the electrode and the path it followed were shown in theory to alter considerably its position in relation to the organ of Corti.

Calculation of total and ionization cross sections for electron scattering by primary benzene compounds

NASA Astrophysics Data System (ADS)

Singh, Suvam; Naghma, Rahla; Kaur, Jaspreet; Antony, Bobby

2016-07-01

The total and ionization cross sections for electron scattering by benzene, halobenzenes, toluene, aniline, and phenol are reported over a wide energy domain. The multi-scattering centre spherical complex optical potential method has been employed to find the total elastic and inelastic cross sections. The total ionization cross section is estimated from total inelastic cross section using the complex scattering potential-ionization contribution method. In the present article, the first theoretical calculations for electron impact total and ionization cross section have been performed for most of the targets having numerous practical applications. A reasonable agreement is obtained compared to existing experimental observations for all the targets reported here, especially for the total cross section.

Parameterized Cross Sections for Pion Production in Proton-Proton Collisions

NASA Technical Reports Server (NTRS)

Blattnig, Steve R.; Swaminathan, Sudha R.; Kruger, Adam T.; Ngom, Moussa; Norbury, John W.; Tripathi, R. K.

2000-01-01

An accurate knowledge of cross sections for pion production in proton-proton collisions finds wide application in particle physics, astrophysics, cosmic ray physics, and space radiation problems, especially in situations where an incident proton is transported through some medium and knowledge of the output particle spectrum is required when given the input spectrum. In these cases, accurate parameterizations of the cross sections are desired. In this paper much of the experimental data are reviewed and compared with a wide variety of different cross section parameterizations. Therefore, parameterizations of neutral and charged pion cross sections are provided that give a very accurate description of the experimental data. Lorentz invariant differential cross sections, spectral distributions, and total cross section parameterizations are presented.

Parenting Style and Family Meals: Cross-Sectional and 5-year Longitudinal Associations

PubMed Central

Berge, Jerica M.; Wall, Melanie; Neumark-Sztainer, Dianne; Larson, Nicole; Story, Mary

2010-01-01

Background Research on family meals in the last decade has shown a positive association between family meal frequency and adolescent healthy dietary intake. However, less is known about factors within the home environment, such as parenting style, which may be associated with family meal patterns. Objective The purpose of this study is to test cross-sectional and five-year longitudinal associations between parenting styles (authoritative, authoritarian, permissive, neglectful) and the frequency of family meals among adolescents. Study Design Data were from Project EAT (Eating Among Teens), a population-based study comprised of youth from diverse ethnic/racial and socioeconomic backgrounds. Two cohorts of adolescents (middle school, high school) completed in-class surveys in 1999 (Time 1) and mailed surveys in 2004 (Time 2). Multiple linear regression models were used to predict mean frequency of family meals at Time 1 and Time 2 from adolescent report of parenting style (both mother and father) at Time 1. Cross-sectional analyses included both adolescent cohorts (n = 4,746) and longitudinal analyses included only the younger cohort (n = 806) because family meal frequency was not assessed in the older cohort at Time 2. Results Cross-sectional results for adolescent girls indicated a positive association between maternal and paternal authoritative parenting style and frequency of family meals. For adolescent boys, maternal authoritative parenting style was associated with more frequent family meals. Longitudinal results indicated that authoritative parenting style predicted higher frequency of family meals five years later, but only between opposite sex parent/adolescent dyads. Conclusions Future research should identify additional factors within the home environment that are associated with family meal frequency in order to develop effective interventions that result in increased family meals for youth. Also, future research should investigate the mealtime behaviors of authoritative parents and identify specific behaviors that dietitians and other health care providers could share with parents of adolescents to help them increase family meal frequency. PMID:20630160

Correlates of smoking among youth: the role of parents, friends, attitudes/beliefs, and demographics.

PubMed

Dietz, Noella A; Arheart, Kristopher L; Sly, David F; Lee, David J; McClure, Laura A

2016-01-01

Family engagement has been shown to play a crucial role in youth cigarette use prevention and uptake. We examine cross-sectional and longitudinal data to determine whether changes in parental monitoring factors influence changes in smoking susceptibility. Two cross-sectional surveys of Florida youth (12-17 years) were conducted in 2009, with a follow-up survey in 2010. Multivariable analyses examined demographics, parent characteristics, family engagement, and parental monitoring on youth susceptibility to smoke. Cross-sectional data show eating together 6+ times/week and doing something for fun 5+ times/week were related to an increased likelihood of Very Low and decreased likelihood of High susceptibility, respectively. Parental monitoring factors and parents tell on a friend who smokes was significantly related to having Very Low susceptibility in both surveys. Mother's education, parent smokes, family engagement factors, and parental monitoring were significant in both survey rounds. Longitudinal analyses showed change in eating together did not significantly affect the odds of change in smoking susceptibility; however, change in the frequency of doing things for fun with a parent showed decreased odds of susceptibility (OR = .63 [.49-.82]), opposite of the hypothesized direction. Lastly, as youth aged, they were more likely to experience a greater odds of decreased susceptibility (OR14-15y = 1.47 [1.08-1.99] and OR≥16y = 1.40 [1.05-1.84], respectively) and less likely to experience an increased odds of susceptibility (OR14-15y = .65 [.49-.86] and OR≥16y = .72 [.56-.93], respectively). We found mixed results for family engagement and parental monitoring on changes in youth smoking susceptibility. Cross-sectional data showed general associations in the expected direction; however, longitudinal analyses showed family engagement variables had significance, but in the opposite hypothesized direction.

Intravenous volume tomographic pulmonary angiography imaging

NASA Astrophysics Data System (ADS)

Ning, Ruola; Strang, John G.; Chen, Biao; Conover, David L.; Yu, Rongfeng

1999-05-01

This study presents a new intravenous (IV) tomographic angiography imaging technique, called intravenous volume tomographic digital angiography (VTDA) for cross sectional pulmonary angiography. While the advantages of IV-VTDA over spiral CT in terms of volume scanning time and resolution have been validated and reported in our previous papers for head and neck vascular imaging, the superiority of IV-VTDA over spiral CT for cross sectional pulmonary angiography has not been explored yet. The purpose of this study is to demonstrate the advantage of isotropic resolution of IV-VTDA in the x, y and z directions through phantom and animal studies, and to explore its clinical application for detecting clots in pulmonary angiography. A prototype image intensifier-based VTDA imaging system has been designed and constructed by modifying a GE 8800 CT scanner. This system was used for a series of phantom and dog studies. A pulmonary vascular phantom was designed and constructed. The phantom was scanned using the prototype VTDA system for direct 3D reconstruction. Then the same phantom was scanned using a GE CT/i spiral CT scanner using the routine pulmonary CT angiography protocols. IV contrast injection and volume scanning protocols were developed during the dog studies. Both VTDA reconstructed images and spiral CT images of the specially designed phantom were analyzed and compared. The detectability of simulated vessels and clots was assessed as the function of iodine concentration levels, oriented angles, and diameters of the vessels and clots. A set of 3D VTDA reconstruction images of dog pulmonary arteries was obtained with different IV injection rates and isotropic resolution in the x, y and z directions. The results of clot detection studies in dog pulmonary arteries have also been shown. This study presents a new tomographic IV angiography imaging technique for cross sectional pulmonary angiography. The results of phantom and animal studies indicate that IV-VTDA is superior to spiral CT for cross sectional pulmonary angiography.

Effect of dexamethasone on mandibular bone biomechanics in rats during the growth phase as assessed by bending test and peripheral quantitative computerized tomography.

PubMed

Bozzini, Clarisa; Champin, Graciela; Alippi, Rosa M; Bozzini, Carlos E

2015-04-01

Long-term glucocorticoid administration to growing rats induces osteopenia and alterations in the biomechanical behavior of the bone. This study was performed to estimate the effects of dexamethasone (DTX), a synthetic steroid with predominant glucocorticoid activity, on the biomechanical properties of the mandible of rats during the growth phase, as assessed by bending test and peripheral quantitative computed tomographic (pQCT) analysis. The data obtained by the two methods will provide more precise information when analyzed together than separately. Female rats aged 23 d (n=7) received 500μg.kg-1 per day of DXT for 4 weeks. At the end of the treatment period, their body weight and body length were 51.3% and 20.6% lower, respectively, than controls. Hemimandible weight and area (an index of mandibular size) were 27.3% and 9.7% lower, respectively. The right hemimandible of each animal was subjected to a mechanical 3-point bending test. Significant weakening of the bone, as shown by a correlative impairment of strength and stiffness, was observed in experimental rats. Bone density and cross-sectional area were measured by pQCT. Cross-sectional, cortical and trabecular areas were reduced by 20% to 30% in the DTX group, as were other cortical parameters, including the bone density, mineral content and cross-sectional moment of inertia. The "bone strength index" (BSI, the product of the pQCT-assessed xCSMI and vCtBMD) was 56% lower in treated rats, which compares well with the 54% and 52% reduction observed in mandibular strength and stiffness determined through the bending test. Data suggest that the corticosteroid exerts a combined, negative action on bone geometry (mass and architecture) and volumetric bone mineral density of cortical bone, which would express independent effects on both cellular (material quality) and tissue (cross-sectional design) levels of biological organization of the skeleton in the species.

Cross-sectional and longitudinal comparisons of metabolic profiles between vegetarian and non-vegetarian subjects: a matched cohort study.

PubMed

Chiu, Yen-Feng; Hsu, Chih-Cheng; Chiu, Tina H T; Lee, Chun-Yi; Liu, Ting-Ting; Tsao, Chwen Keng; Chuang, Su-Chun; Hsiung, Chao A

2015-10-28

Several previous cross-sectional studies have shown that vegetarians have a better metabolic profile than non-vegetarians, suggesting that a vegetarian dietary pattern may help prevent chronic degenerative diseases. However, longitudinal studies on the impact of vegetarian diets on metabolic traits are scarce. We studied how several sub-types of vegetarian diets affect metabolic traits, including waist circumference, BMI, systolic blood pressure (SBP), diastolic blood pressure, fasting blood glucose, total cholesterol (TC), HDL, LDL, TAG and TC:HDL ratio, through both cross-sectional and longitudinal study designs. The study used the MJ Health Screening database, with data collected from 1994 to 2008 in Taiwan, which included 4415 lacto-ovo-vegetarians, 1855 lacto-vegetarians and 1913 vegans; each vegetarian was matched with five non-vegetarians based on age, sex and study site. In the longitudinal follow-up, each additional year of vegan diet lowered the risk of obesity by 7 % (95 % CI 0·88, 0·99), whereas each additional year of lacto-vegetarian diet lowered the risk of elevated SBP by 8 % (95 % CI 0·85, 0·99) and elevated glucose by 7 % (95 % CI 0·87, 0·99), and each additional year of ovo-lacto-vegetarian diet increased abnormal HDL by 7 % (95 % CI 1·03, 1·12), compared with non-vegetarians. In the cross-sectional comparisons, all sub-types of vegetarians had lower likelihoods of abnormalities compared with non-vegetarians on all metabolic traits (P<0·001 for all comparisons), except for HDL and TAG. The better metabolic profile in vegetarians is partially attributable to lower BMI. With proper management of TAG and HDL, along with caution about the intake of refined carbohydrates and fructose, a plant-based diet may benefit all aspects of the metabolic profile.

Parenting style and family meals: cross-sectional and 5-year longitudinal associations.

PubMed

Berge, Jerica M; Wall, Melanie; Neumark-Sztainer, Dianne; Larson, Nicole; Story, Mary

2010-07-01

Research on family meals in the past decade has shown a positive association between family meal frequency and adolescent healthy dietary intake. However, less is known about factors within the home environment, such as parenting style, that may be associated with family meal patterns. The purpose of this study is to test cross-sectional and 5-year longitudinal associations between parenting styles (authoritative, authoritarian, permissive, and neglectful) and the frequency of family meals among adolescents. Data were from Project Eating Among Teens, a population-based study comprised of youth from diverse ethnic/racial and socioeconomic backgrounds. Two cohorts of adolescents (middle school and high school) completed in-class surveys in 1999 (Time 1) and mailed surveys in 2004 (Time 2). Multiple linear regression models were used to predict mean frequency of family meals at Time 1 and Time 2 from adolescent report of parenting style (both mother and father) at Time 1. Cross-sectional analyses included both adolescent cohorts (n=4,746) and longitudinal analyses included only the younger cohort (n=806) because family meal frequency was not assessed in the older cohort at Time 2. Cross-sectional results for adolescent girls indicated a positive association between maternal and paternal authoritative parenting style and frequency of family meals. For adolescent boys, maternal authoritative parenting style was associated with more frequent family meals. Longitudinal results indicated that authoritative parenting style predicted higher frequency of family meals 5 years later, but only between opposite sex parent/adolescent dyads. Future research should identify additional factors within the home environment that are associated with family meal frequency to develop effective interventions that result in increased family meals for youth. Also, future research should investigate the mealtime behaviors of authoritative parents and identify specific behaviors that dietetics practitioners and other health care providers could share with parents of adolescents to help them increase family meal frequency. Copyright 2010 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

Cross-sectional and longitudinal associations between different exercise types and food cravings in free-living healthy young adults.

PubMed

Drenowatz, Clemens; Evensen, Line H; Ernstsen, Linda; Blundell, John E; Hand, Gregory A; Shook, Robin P; Hébert, James R; Burgess, Stephanie; Blair, Steven N

2017-11-01

An increase in energy intake due to alterations in hedonic appetite sensations may, at least in part, contribute to lower-than-expected weight loss in exercise interventions. The aim of this study was to examine cross-sectional and longitudinal associations between habitual exercise participation and food cravings in free-living young adults. A total of 417 adults (49% male, 28 ± 4 years) reported frequency and duration of walking, aerobic exercise, resistance exercise and other exercise at baseline and every 3 months over a 12-month period. Food cravings were assessed via the Control of Eating Questionnaire at baseline and 12-month follow-up. Cross-sectional analyses revealed more frequent cravings for chocolate and a greater difficulty to resist food cravings in women compared to men (p < 0.01). Only with resistance exercise significant sex by exercise interaction effects were observed with favorable responses in men but not in women. Significant main effects were shown for walking and aerobic exercise with exercisers reporting more frequent food cravings for chocolate and fruits and greater difficulty to resist eating compared to non-exercisers (p < 0.05). Longitudinal analyses revealed significant interaction effects for other exercise (p < 0.05) with favorable results in men but not women. Furthermore, significant main effects were observed for aerobic exercise, resistance exercise and total exercise with an increase in exercise being associated with a reduced difficulty to resist food cravings (p < 0.05). The association between exercise participation and hedonic appetite sensations varies by exercise type and sex. Even though exercise was associated with more frequent and greater difficulty to food cravings in the cross-sectional analyses, which may be attributed to greater energy demands, longitudinal results indicate beneficial effects of increased exercise on appetite control, particularly in men. Copyright © 2017 Elsevier Ltd. All rights reserved.

Systematic review on the association between employee worktime control and work-non-work balance, health and well-being, and job-related outcomes.

PubMed

Nijp, Hylco H; Beckers, Debby G J; Geurts, Sabine A E; Tucker, Philip; Kompier, Michiel A J

2012-07-01

The aim of this review was to assess systematically the empirical evidence for associations between employee worktime control (WTC) and work-non-work balance, health/well-being, and job-related outcomes (eg, job satisfaction, job performance). A systematic search of empirical studies published between 1995-2011 resulted in 63 relevant papers from 53 studies. Five different categories of WTC measurements were distinguished (global WTC, multidimensional WTC, flextime, leave control, and "other subdimensions of WTC"). For each WTC category, we examined the strength of evidence for an association with (i) work-non-work balance, (ii) health/well-being, and (iii) job-related outcomes. We distinguished between cross-sectional, longitudinal, and intervention studies. Evidence strength was assessed based on the number of studies and their convergence in terms of study findings. (Moderately) strong cross-sectional evidence was found for positive associations between global WTC and both work-non-work balance and job-related outcomes, whereas no consistent evidence was found regarding health/well-being. Intervention studies on global WTC found moderately strong evidence for a positive causal association with work-non-work balance and no or insufficient evidence for health/well-being and job-related outcomes. Limited to moderately strong cross-sectional evidence was found for positive associations between multidimensional WTC and our outcome categories. Moderately strong cross-sectional evidence was found for positive associations between flextime and all outcome categories. The lack of intervention or longitudinal studies restricts clear causal inferences. This review has shown that there are theoretical and empirical reasons to view WTC as a promising tool for the maintenance of employees' work-non-work balance, health and well-being, and job-related outcomes. At the same time, however, the current state of evidence allows only very limited causal inferences to be made regarding the impact of enhanced WTC.

Noncircular Cross Sections Could Enhance Mixing in Sprays

NASA Technical Reports Server (NTRS)

Bellan, Josette; Abdel-Hameed, Hesham

2003-01-01

A computational study has shown that by injecting drops in jets of gas having square, elliptical, triangular, or other noncircular injection cross sections, it should be possible to increase (relative to comparable situations having circular cross section) the entrainment and dispersion of liquid drops. This finding has practical significance for a variety of applications in which it is desirable to increase dispersion of drops. For example, in chemical-process sprays, increased dispersion leads to increases in chemical- reaction rates; in diesel engines, increasing the dispersion of drops of sprayed fuel reduces the production of soot; and in household and paint sprays, increasing the dispersion of drops makes it possible to cover larger surfaces. It has been known for some years that single-phase fluid jets that enter flow fields through noncircular inlets entrain more fluid than do comparable jets entering through circular inlets. The computational study reported here was directed in part toward determining whether and how this superior mixing characteristic of noncircular single phase jets translates to a similar benefit in cases of two-phase jets (that is, sprays). The study involved direct numerical simulations of single- and two-phase free jets with circular, elliptical, rectangular, square, and triangular inlet cross sections. The two-phase jets consisted of gas laden with liquid drops randomly injected at the inlets. To address the more interesting case of evaporating drops, the carrier gas in the jets was specified to be initially unvitiated by the vapor of the liquid chemical species and the initial temperature of the drops was chosen to be smaller than that of the gas. The mathematical model used in the study was constructed from the conservation equations for the two-phase flow and included complete couplings of mass, momentum, and energy based on thermodynamically self-consistent specification of the enthalpy, internal energy, and latent heat of vaporization of the vapor.

An investigation of MCNP6.1 beryllium oxide S(α, β) cross sections

DOE PAGES

Sartor, Raymond F.; Glazener, Natasha N.

2016-03-08

In MCNP6.1, materials are constructed by identifying the constituent isotopes (or elements in a few cases) individually. This list selects the corresponding microscopic cross sections calculated from the free-gas model to create the material macroscopic cross sections. Furthermore, the free-gas model and the corresponding material macroscopic cross sections assume that the interactions of atoms do not affect the nuclear cross sections.

DBCC Software as Database for Collisional Cross-Sections

NASA Astrophysics Data System (ADS)

Moroz, Daniel; Moroz, Paul

2014-10-01

Interactions of species, such as atoms, radicals, molecules, electrons, and photons, in plasmas used for materials processing could be very complex, and many of them could be described in terms of collisional cross-sections. Researchers involved in plasma simulations must select reasonable cross-sections for collisional processes for implementing them into their simulation codes to be able to correctly simulate plasmas. However, collisional cross-section data are difficult to obtain, and, for some collisional processes, the cross-sections are still not known. Data on collisional cross-sections can be obtained from numerous sources including numerical calculations, experiments, journal articles, conference proceedings, scientific reports, various universities' websites, national labs and centers specifically devoted to collecting data on cross-sections. The cross-sections data received from different sources could be partial, corresponding to limited energy ranges, or could even not be in agreement. The DBCC software package was designed to help researchers in collecting, comparing, and selecting cross-sections, some of which could be constructed from others or chosen as defaults. This is important as different researchers may place trust in different cross-sections or in different sources. We will discuss the details of DBCC and demonstrate how it works and why it is beneficial to researchers working on plasma simulations.

Plasma levels of the pro-inflammatory protein S100A12 (EN-RAGE) are associated with muscle and fat mass in hemodialysis patients: a cross-sectional study

PubMed Central

2014-01-01

Background Malnutrition is highly prevalent and contributes to mortality in hemodialysis (HD) patients. Although the receptor for advanced glycation end products (RAGE) system also contributes to the morbidity and mortality of these patients, the role that the RAGE system plays in determining nutritional status is currently unknown. Methods A cross-sectional study examining 79 HD patients was performed. The plasma concentrations of the soluble RAGE (sRAGE) and S100A12 (also known as EN-RAGE) were studied to evaluate their association with nutritional status, which was assessed by measuring the mid-thigh muscle mass and subcutaneous fat mass with computed tomography. Results Plasma S100A12 concentrations were shown to be significantly and negatively correlated with muscle mass and with fat mass (r = −0.237, P < 0.05 and r = −0.261, P < 0.05, respectively). In contrast, sRAGE was not shown to significantly correlate with either of these factors. Multiple regression analyses demonstrated that S100A12 is a significant independent predictor of both muscle mass and fat mass (P < 0.01 and P < 0.05, respectively). Conclusions Our findings suggest that plasma S100A12 levels could play an important role in determining muscle mass and fat mass in HD patients. Trial registration Study number; UMIN000012341. PMID:24884769

Wheelchair-specific fitness of persons with a long-term spinal cord injury: cross-sectional study on effects of time since injury and physical activity level.

PubMed

de Groot, Sonja; van der Scheer, Jan W; Bakkum, Arjan J T; Adriaansen, Jacinthe J E; Smit, Christof A; Dijkstra, Catja; Post, Marcel W M; van der Woude, Lucas H V

2016-01-01

To study the impact of time since injury (TSI) and physical activity (PA) on fitness of persons with spinal cord injury (SCI). Cross-sectional study. Persons with SCI (N = 158) in three TSI strata: 10-19, 20-29 and ≥30 years after SCI and divided in an active and inactive group. Fitness [peak power output (POpeak) and peak oxygen uptake (VO2peak)] was assessed. In persons with tetraplegia, no significant relationship was found between TSI and fitness after controlling for confounders, while a higher activity level was related to a higher POpeak in this group. Active people with tetraplegia also showed less decline in POpeak with an increase in TSI compared to inactive people. In persons with paraplegia, after controlling for confounders, it was shown that TSI had a negative effect on POpeak, while PA was not significantly associated with fitness in people with paraplegia. In people with paraplegia, fitness was significantly lower in those with a longer TSI. Persons with a long TSI might need more attention to remain fit and PA might be an important element in that respect as shown by the results of the group with a tetraplegia. Wheelchair-specific fitness seems to diminish over time after paraplegia. An active lifestyle is related to wheelchair-specific fitness in persons with tetraplegia. Prevention of long-term deconditioning is very important.

Compact Assumption Applied to the Monopole Term of Farassat's Formulations

NASA Technical Reports Server (NTRS)

Lopes, Leonard V.

2015-01-01

Farassat's formulations provide an acoustic prediction at an observer location provided a source surface, including motion and flow conditions. This paper presents compact forms for the monopole term of several of Farassat's formulations. When the physical surface is elongated, such as the case of a high aspect ratio rotorcraft blade, compact forms can be derived which are shown to be a function of the blade cross sectional area by reducing the computation from a surface integral to a line integral. The compact forms of all formulations are applied to two example cases: a short span wing with constant airfoil cross section moving at three forward flight Mach numbers and a rotor at two advance ratios. Acoustic pressure time histories and power spectral densities of monopole noise predicted from the compact forms of all the formulations at several observer positions are shown to compare very closely to the predictions from their non-compact counterparts. A study on the influence of rotorcraft blade shape on the high frequency portion of the power spectral density shows that there is a direct correlation between the aspect ratio of the airfoil and the error incurred by using the compact form. Finally, a prediction of pressure gradient from the non-compact and compact forms of the thickness term of Formulation G1A shows that using the compact forms results in a 99.6% improvement in computation time, which will be critical when noise is incorporated into a design environment.

Effect of wave-current interaction on wind-driven circulation in narrow, shallow embayments

USGS Publications Warehouse

Signell, Richard P.; Beardsley, Robert C.; Graber, H. C.; Capotondi, A.

1990-01-01

The effect of wind waves on the steady wind-driven circulation in a narrow, shallow bay is investigated with a two-dimensional (y, z) circulation model and the Grant and Madsen [1979] bottom-boundary layer model, which includes wave-current interaction. A constant wind stress is applied in the along-channel x direction to a channel with a constant cross-sectional profile h(y). The wind-induced flushing of shallow bays is shown to be sensitive to both the shape of the cross section and the effects of surface waves. The flushing increases with increasing , where h′ is the standard deviation of cross-channel depth and  is the mean depth. This is consistent with the findings of Hearn et al. [1987]. The flushing decreases, however, with the inclusion of surface wave effects which act to increase the bottom drag felt by the currents. Increasing effective bottom friction reduces the strength of the circulation, while the along-bay surface slope, bottom stress and the structure of current profiles remain nearly unchanged. An implication of the circulation dependence on wave-current interaction is that low-frequency oscillatory winds may drive a mean circulation when the wave field changes with wind direction.x

A comparison of total reaction cross section models used in particle and heavy ion transport codes

NASA Astrophysics Data System (ADS)

Sihver, Lembit; Lantz, M.; Takechi, M.; Kohama, A.; Ferrari, A.; Cerutti, F.; Sato, T.

To be able to calculate the nucleon-nucleus and nucleus-nucleus total reaction cross sections with precision is very important for studies of basic nuclear properties, e.g. nuclear structure. This is also of importance for particle and heavy ion transport calculations because, in all particle and heavy ion transport codes, the probability function that a projectile particle will collide within a certain distance x in the matter depends on the total reaction cross sections. Furthermore, the total reaction cross sections will also scale the calculated partial fragmentation cross sections. It is therefore crucial that accurate total reaction cross section models are used in the transport calculations. In this paper, different models for calculating nucleon-nucleus and nucleus-nucleus total reaction cross sections are compared and discussed.

Vertically stabilized elongated cross-section tokamak

DOEpatents

Sheffield, George V.

1977-01-01

This invention provides a vertically stabilized, non-circular (minor) cross-section, toroidal plasma column characterized by an external separatrix. To this end, a specific poloidal coil means is added outside a toroidal plasma column containing an endless plasma current in a tokamak to produce a rectangular cross-section plasma column along the equilibrium axis of the plasma column. By elongating the spacing between the poloidal coil means the plasma cross-section is vertically elongated, while maintaining vertical stability, efficiently to increase the poloidal flux in linear proportion to the plasma cross-section height to achieve a much greater plasma volume than could be achieved with the heretofore known round cross-section plasma columns. Also, vertical stability is enhanced over an elliptical cross-section plasma column, and poloidal magnetic divertors are achieved.

Dose-response relationships between occupational exposure to potash, diesel exhaust and nitrogen oxides and lung function: cross-sectional and longitudinal study in two salt mines.

PubMed

Lotz, Gabriele; Plitzko, Sabine; Gierke, Erhardt; Tittelbach, Ulrike; Kersten, Norbert; Schneider, W Dietmar

2008-08-01

Several studies have shown that underground salt miners may have an increased incidence of chest symptoms and sometimes decreased lung function. Miners of two salt mines were investigated to evaluate relationships between the lung function and the workplace exposure. The effect of nitrogen monoxide (NO) and nitrogen dioxide (NO(2)) was investigated in view of the recent debate on European occupational exposure limits. A total of 410/463 miners (mine A/mine B) were examined cross-sectional and 75/64% of the first cohort were examined after a 5-year period. Exposure was measured by personal sampling. Personal lifetime exposure doses of salt dust, diesel exhaust, NO(2) and NO were calculated for all miners. Dose-response relationships were calculated by multiple regression analysis. Each exposure component acted as an indicator for the complex exposure. Exposure response relationships were shown in the cross-sectional and longitudinal investigations in both mines. In the 5-year period, the adjusted (age, smoking, etc.) effect of the exposure indicators resulted in a mean decrease of FEV(1) between -18 ml/year (mine A) and -10 ml/year (mine B). The personal concentrations related to this effect were 12.6/7.1 mg/m(3) inhalable dust, 2.4/0.8 mg/m(3) respirable dust, 0.09/0.09 mg/m(3) diesel exhaust, 0.4/0.5 ppm NO(2) and 1.7/1.4 ppm NO (mine A/B). Exposure was related to symptoms of chronic bronchitis only in mine B. The effects found in both mines indicate that the mixed exposure can cause lung function disorders in salt miners exposed over a long time. Because of the high correlation of the concentrations it was not possible to determine the effects of a single exposure component separately or to recommend a specific occupational exposure limit. However, possible maximum effects associated with the mixed exposure can be evaluated in the ranges of concentrations of the individual substances in the mines.

Porosity, Mineralization, Tissue Type and Morphology Interactions at the Human Tibial Cortex

NASA Astrophysics Data System (ADS)

Hampson, Naomi A.

Prior research has shown a relationship between tibia robustness (ratio of cross-sectional area to bone length) and stress fracture risk, with less robust bones having a higher risk, which may indicate a compensatory increase in elastic modulus to increase bending strength. Previous studies of human tibiae have shown higher ash content in slender bones. In this study, the relationships between variations in volumetric porosity, ash content, tissue mineral density, secondary bone tissue, and cross sectional geometry, were investigated in order to better understand the tissue level adaptations that may occur in the establishment of cross-sectional properties. In this research, significant differences were found between porosity, ash content, and tissue type around the cortex between robust and slender bones, suggesting that there was a level of co-adaption occurring. Variation in porosity correlated with robustness, and explained large parts of the variation in tissue mineral density. The nonlinear relationship between porosity and ash content may support that slender bones compensate for poor geometry by increasing ash content through reduced remodeling, while robust individuals increase porosity to decrease mass, but only to a point. These results suggest that tissue level organization plays a compensatory role in the establishment of adult bone mass, and may contribute to differences in bone aging between different bone phenotypes. The results suggest that slender individuals have significantly less remodeled bone, however the proportion of remodeled bone was not uniform around the tibia. In the complex results of the study of 38% vs. 66% sites the distal site was subject to higher strains than the 66% site, indicating both local and global regulators may be affecting overall remodeling rates and need to be teased apart in future studies. This research has broad clinical implications on the diagnosis and treatment of fragility fractures. The relationships that were found between local variables and global geometry indicate that there was a fundamental difference between robust and slender bones, which affect the overall properties of the bone. This could allow for simple testing of bone geometry to predict an individual's fracture risk.

Controlling the Release of Indomethacin from Glass Solutions Layered with a Rate Controlling Membrane Using Fluid-Bed Processing. Part 1: Surface and Cross-Sectional Chemical Analysis.

PubMed

Dereymaker, Aswin; Scurr, David J; Steer, Elisabeth D; Roberts, Clive J; Van den Mooter, Guy

2017-04-03

Fluid bed coating has been shown to be a suitable manufacturing technique to formulate poorly soluble drugs in glass solutions. Layering inert carriers with a drug-polymer mixture enables these beads to be immediately filled into capsules, thus avoiding additional, potentially destabilizing, downstream processing. In this study, fluid bed coating is proposed for the production of controlled release dosage forms of glass solutions by applying a second, rate controlling membrane on top of the glass solution. Adding a second coating layer adds to the physical and chemical complexity of the drug delivery system, so a thorough understanding of the physical structure and phase behavior of the different coating layers is needed. This study aimed to investigate the surface and cross-sectional characteristics (employing scanning electron microscopy (SEM) and time of flight secondary ion mass spectrometry (ToF-SIMS)) of an indomethacin-polyvinylpyrrolidone (PVP) glass solution, top-coated with a release rate controlling membrane consisting of either ethyl cellulose or Eudragit RL. The implications of the addition of a pore former (PVP) and the coating medium (ethanol or water) were also considered. In addition, polymer miscibility and the phase analysis of the underlying glass solution were investigated. Significant differences in surface and cross-sectional topography of the different rate controlling membranes or the way they are applied (solution vs dispersion) were observed. These observations can be linked to the polymer miscibility differences. The presence of PVP was observed in all rate controlling membranes, even if it is not part of the coating solution. This could be attributed to residual powder presence in the coating chamber. The distribution of PVP among the sample surfaces depends on the concentration and the rate controlling polymer used. Differences can again be linked to polymer miscibility. Finally, it was shown that the underlying glass solution layer remains amorphous after coating of the rate controlling membrane, whether formed from an ethanol solution or an aqueous dispersion.

The single scattering properties of soot aggregates with concentric core-shell spherical monomers

NASA Astrophysics Data System (ADS)

Wu, Yu; Cheng, Tianhai; Gu, Xingfa; Zheng, Lijuan; Chen, Hao; Xu, Hui

2014-03-01

Anthropogenic soot aerosols are shown as complex, fractal-like aggregated structures with high light absorption efficiency. In atmospheric environment, soot monomers may tend to acquire a weakly absorbing coating, such as an organic coating, which introduces further complexity to the optical properties of the aggregates. The single scattering properties of soot aggregates can be significantly influenced by the coated status of these kinds of aerosols. In this article, the monomers of fractal soot aggregates are modelled as semi-external mixtures (physical contact) with constant radius of soot core and variable sizes of the coating for specific soot volume fractions. The single scattering properties of these coated soot particles, such as phase function, the cross sections of extinction and absorption, single scattering albedo (SSA) and asymmetry parameter (ASY), are calculated using the numerically exact superposition T-matrix method. The random-orientation averaging results have shown that the single scattering properties of these coated soot aggregates are significantly different from the single volume-equivalent core-shell sphere approximation using the Mie theory and the homogeneous aggregates with uncoated monomers using the effective medium theory, such as Maxwell-Garnett and Bruggemann approximations, which overestimate backscattering of coated soot. It is found that the SSA and cross sections of extinction and absorption are increased for soot aggregates with thicker weakly absorbing coating on the monomers. Especially, the SSA values of these simulated aggregates with less soot core volume fractions are remarkably (~50% for core volume fraction of soot aggregates of 0.5, ~100% for a core volume fraction of 0.2, at 0.67 μm) larger than for uncoated soot particles without consideration of coating. Moreover, the cross sections of extinction and absorption are underestimated by the computation of equivalent homogeneous fractal aggregate approximation (within 5% for the T-matrix method and 10-25% for the Rayleigh-Debye-Gans approximation due to different soot volume fractions). Further understanding of the optical properties of these coated soot aggregates would be helpful for both environment monitoring and climate studies.

BACKSCAT Lidar Simulation Version 3.0: Technical Documentation and Users Guide

DTIC Science & Technology

1992-12-03

Raman Cross Section of Some Simple Gases, J. Opt. Soc. Am., 63:73. 20 Penny, C.M., St. Peters, R.L., and Lapp, M., (1974) Absolute Rotational Raman...of the molecule, and the remaining columns list the relative normalized cross sections for the respective excitation wavelength. The absolute Raman...cross section is obtained by simply multiplying the relative normalized cross section for a molecular species of interest by the absolute cross section