bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origins of the energy distribution structure in coherent pion production at intermediate energies
Authors: Deutchman P A 
Published: April 2011

New calculations have been done that now cover the intermediate energy range from 100 MeV/nucleon to 2.0 GeV/nucleon incident energy for the reaction 12C + 12C [Formula: see text] 12C + 12C (15.11 MeV) +π0, where constructive, coherent Δ-hole states are excited in either nucleus while the companion nucleus is excited to a coherent nucleonhole state describing the spinisospin, giant resonant state at 15.11 MeV. The Δ (1232 MeV) isobar then decays to a nucleon and pion. Theoretical pion energy distributions are calculated and, for the first time, results above 400 MeV/nucleon are shown. A theoretical basis for understanding how the shapes of the pion distributions change as a function of incident energy is described. The fundamental shape of the Δ-production amplitude as a function of momentum transfer is discussed and the effects of the energy-dependent nuclear width are examined. Furthermore, the connection between the origins of the pion distribution to the final pion shapes is made and the importance of the giant resonance in providing an important signature is pointed out. By pushing the calculations above 400 MeV/nucleon, it was discovered that sliding kinematics and kinematic turnarounds occur due to the two-to-three-body sequential nature of the reactions and these effects determine the final structure of the pion distributions at higher incident energies. PACS Nos.: 24.10Cn, 24.30Cz, 25.70-z, 25.80-e
About the Dunham coefficients Y20 and Y11 for diatomic molecules
Authors: Sharma A K , Chandra S 
Published: April 2011

For a diatomic molecule, when the Dunham coefficient Y20 is negative, all features of the potential-energy curve can be reproduced. When Y20 is positive, it is not possible to reproduce all features of the potential-energy curve. However, the turning points for some lower vibrational states can be obtained. PACS No.: 33.15Mt
Exact vs. quasi-classical tunneling times for idealized potentials
Authors: Shegelski M R.A. , Reid M , Holenstein R 
Published: April 2011

We compare the exact tunneling time with the quasi-classical tunneling time for idealized potentials. We examine three one-dimensional cases where the potential is chosen to have a simple form. In each case, the exact tunneling time and the quasi-classical time differ significantly. In one case, the two differ in magnitude by a factor of about ten. In another case, the two differ not only quantitatively, but qualitatively as well. A discussion is given as to why the two times are significantly different, and suggestions for further inquiries are made. PACS Nos.: 03.65Xp, 03.65-w
Examination of the perturbative expansion parameter for piezo-electric coupling in CdS
Authors: Lee J H , Yi S N , Jo S G , Choi S D 
Published: April 2011

A perturbative expansion parameter ε is introduced for reformulating the continued-fraction representation of the magneto-optical absorption linewidth function into a power-series expansion. The parameterε is calculated for cadmium sulfide, in which the piezoelectric coupling is dominant, by fitting the theory into the available experiment. The temperature dependence in the quantum limit is shown to be ε T2=1.8, where T is the temperature given in kelvins, or the parameter decreases monotonously as the temperature increases. This is thought to be due to our choice of the continued fraction, which involves the flux variables along with the projectors. We guess that for other piezoelectric materials, the magneto-optical absorption data will have a similar temperature dependence. It is to be regretted that the dependence cannot be checked for the other materials due to lack of experimental data. PACS Nos.: 76.20+q, 76.40+b, 78.20Ls
Modeling the spectral line shapes with speed-dependent broadening and Dicke narrowing
Authors: Shapiro D A , Ciurylo R , Jaworski R , May A D 
Published: April 2011

Shapes of pressure- and Doppler-broadened spectral lines are obtained by solving exactly a three-dimension transport and (or) relaxation equation. The speed dependence of collisional broadening and shifting caused by dephasing collisions and Dicke narrowing caused by velocity-changing collisions are taken into account within the impact approximation. The RautianSobelman and KeilsonStorer models are used to describe velocity-changing collisions. We show in the high density or hydrodynamic limit that both models lead to a profile that is the weighted sum of Lorentz profiles if the collisional broadening is much greater than the frequency of velocity-changing collisions and to the ordinary Lorentz profile in the opposite case. This shows that the relative size of the optical and kinetic cross section is important in determining the shape of absorption curves. The analytical solutions may be useful in modeling absorption profiles for remote sensing of the atmosphere. PACS No.: 32.70Jz
Ga-NMR local susceptibility of the Kagome-based magnet SrCr9p Ga129pO19: A high-temperature study
Authors: Limot L , Mendels P , Collin G , Mondelli C , Mutka H , Blanchard N 
Published: April 2011

We report a high-T GaNMR study in the Kagome-based anti-ferromagnetic compound SrCr9pGa129pO19 (0.81 [Formula: see text] p [Formula: see text] 0.96), and present a refined mean-field analysis of the local NMR susceptibility of Cr-frustrated moments. We find that the intralayer Kagome coupling is J = 86(6) K, and the interlayer coupling to non-Kagome Cr moments is J' = 69(7) K. The J' / J = 0.80(1) ratio confirms the common belief that the frustrated entity is a pyrochlore slab. PACS Nos.:75.30Cr, 75.50Lk, 76.60-k
Structural and magnetic characterization of Ho3SbO7 and Dy3SbO7
Authors: Fennell T , Bramwell S T , Green M A 
Published: April 2011

We present an experimental investigation of the structural and magnetic properties of Ho3SbO7 and Dy3SbO7. These compounds adopt the Y3TaO7 structure, space group C2221. The magnetic rare-earth ions occupy an intricate lattice related to the pyrochlore lattice that occurs in Ho2Ti2O7 and Dy2Ti2O7. The crystal structure of Ho3SbO7 is determined by Rietveld refinement of the powder X-ray diffraction pattern at ambient temperature, and that of the Dy analogue is inferred to be similar. Magnetic susceptibility measurements show that Ho3SbO7 and Dy3SbO7 have negative CurieWeiss temperatures: 8.4 K (Ho) and 9.2 K (Dy). Magnetic transitions have been detected at 2.0 K (Ho) and 3.0 K (Dy). We discuss the results in terms of the ``dipolar spin ice model'' that has been used to describe Ho2Ti2O7 and Dy2Ti2O7. PACS Nos.: 75.25+z, 75.50Ee, 61.10Nz
Spin- and chirality-orderings of frustrated magnets  stacked-triangular anti-ferromagnets and spin glasses
Authors: Kawamura H 
Published: April 2011

"Chirality" is a multispin quantity representing the sense or the handedness of the noncollinear spin structures induced by spin frustration. Recent studies have revealed that the chirality often plays an important role in the ordering of certain frustrated magnets. Here I take up two such examples, stacked-triangular anti-ferromagnets and spin glasses, where the inherent chiral degree of freedom affects underlying physics and might lead to novel ordering phenomena. The first topic is the criticality of the magnetic-phase transition of vector (i.e., XY or Heisenberg) anti-ferromagnets on the three-dimensional stacked-triangular lattice. The second topic is the nature of the spin-glass ordering. I will review the recent theoretical and experimental works on these topics, with particular emphasis on the important role played by the chirality. PACS Nos.: 67.70+n, 67.57Lm
First-order transition in frustrated Yb2Ti2O7 without long-range order
Authors: Hodges J A , Bonville P , Forget A , André G 
Published: April 2011

We have examined the pyrochlore lattice compound Yb2Ti2O7 using 170Yb Mössbauer spectroscopy and neutron diffraction. The Yb3+ ion has a well-isolated S' = 1/2 ground state with planar anisotropy and the net interaction is ferromagnetic. The Mössbauer measurements show that short-range correlations develop below about 2 K and at 0.2 K, where specific heat data evidence a λ-transition (Blöte et al. Physica, 43, 549 (1969)), there is a first-order transition to a state where the Yb3+ moments become blocked on the Mössbauer time scale (108 s) with well-defined directions. The neutron diffraction measurements show that below 0.2 K there is no long-range magnetic order. PACS Nos.: 75.40-s, 76.80+y, 75.50Dd
Magnetization plateaux and bound states of the ShastrySutherland model for SrCu2(BO3)2
Authors: Momoi T , Totsuka K 
Published: April 2011

In this paper, we briefly review our recent studies of the Heisenberg anti-ferromagnet on the ShastrySutherland lattice for SrCu2(BO3)2 under magnetic fields. Treating magnetic excitations promoted by the field as Bose particles and using a strong-coupling expansion, we derived an effective Hamiltonian for the magnetic particles. Anisotropic repulsive interactions between particles induce "insulating" states with a stripe spin-density wave structure at magnetization m/msat = 1/3 and with a checkerboard structure at 1/2, and thereby form magnetization plateaux. We also demonstrated how the unique geometry of the ShastrySutherland lattice affects dynamical properties and makes a novel type of quintuplet (S = 2) bound states condense for very small magnetization. PACS Nos.: 75.50-y, 75.60Ej, 75.10Jm
Peculiarities of spontaneous-grating formation in light-sensitive films under elliptically polarized laser radiation
Authors: Miloslavsky V K , Ageev L A , Nahal A 
Published: April 2011

The formation of spontaneous gratings in thin waveguide AgClAg photosensitive films was studied under elliptically polarized laser radiation. New peculiarities of the gratings growth were found (i) a deviation in angular position of the wave vectors of the most probable microgratings from π / 2 about the major axis of the polarization ellipse; and (ii) an asymmetry, which depends on the ellipticity sign, in the diffraction and small-angle scattering patterns. The experimental results are explained within the framework of a model that shows the scattering of incident light by small prolate absorptive Ag spheroids oriented across the major axis of the ellipse and arising from the stage of photoinduced dichroism that precedes grating formation. We show that the dependence of the diffraction patterns' asymmetry on the ellipticity sign is related to an instability due to the angular position of the wave vectors of the most probable microgratings. PACS No. 78.65
The spherically symmetric model of eH scattering
Authors: Temkin A , Wang Y D , Bhatia A K , Sullivan E C 
Published: April 2011

The spherically symmetric model (SSM) for electron--hydrogen scattering is one in which the Coulomb repulsion between the electrons, 2/r12, is replaced by 2/r>, where r> is the greater of r1 or r2. The partial wave decomposition of the wave function for this model is carried out with emphasis on L > 0 partial waves, in which case it is shown that singlet and triplet results are identical. The model, nevertheless, retains all inelastic and ionization channels, and therefore provides a nontrivial testing ground for methods of calculation. The decomposition results in two-dimensional partial differential equations (PDEs). Here numerical calculations are carried out in two ways using (i) a propagation method, and (ii) a noniterative PDE method. The latter is augmented by an integral formula, which greatly enhances the practicality of the method. Elastic phase shifts for L = 1,2,3 partial waves in the elastic region are presented. PACS No. 34.80
B2Σ+ state lifetime in CO+
Authors: Scholl T J , Rosner S D , Holt R A 
Published: April 2011

We measured the lifetime of the B2Σ+, v = 0 level of the astrophysically important CO+ molecule by applying the collinear beam-laser method. Ions in the long-lived A2Π level were excited to the B2Σ+ state by a single-frequency laser beam in resonance with a transition in the B2Σ+  A2Π BaldetJohnson band, and the laser-induced fluorescence from the B2Σ+  X2Σ+ First Negative band was monitored as a function of distance from the excitation region. We claim that our result of 54.9 ± 0.7 ns is less likely to have suffered from systematic error than previous measurements, which were mutually discordant. PACS No. 33.70Ca
Article
Authors: Kurunczi P , Becker K , Martus K 
Published: April 2011

The vacuum ultraviolet (VUV) emissions of the hydrogen Lyman series following the dissociative excitation of the Si-organic compounds tetraethoxysilane (TEOS), tetramethylsilane (TMS), and hexamethyldisiloxane (HMDSO) by controlled electron impact were analyzed. Absolute photoemission cross sections from threshold to 200 eV and appearance potentials were determined for the Lyman-α and Lyman-β emissions for each of the three targets. The measured apparent emission cross sections at 100 eV impact energy for the Lyman-α lines are 6.0 x 10-19 cm2 for TMS, 6.5 x 10-19 cm2 for HMDSO and 1.1 x 10-18 cm2 for TEOS. The apparent Lyman-α cross sections for all three targets contained significant cascade contributions from the H Balmer series. Detailed studies of the near threshold regions indicated that several break-up mechanisms of the parent molecules contribute to the emissions. The lowest onsets for HMDSO, and TEOS were attributed to the removal of a single excited atomic hydrogen atom in the n=2 state. Additional onsets at higher energies could not be uniquely correlated in all cases with a particular break-up channel and (or) cascading, since the other fragments in these processes were not identified. The Lyman-β apparent emission cross sections were also measured and we found values of 1.3 x 10-19 cm2 for TMS, 1.6 x 10-19 cm2 for HMDSO, and 2.0 x 10-19 cm2 for TEOS at an impact energy of 100 eV. PACS Nos. 52.20Fs and 34.80Gs
Sur les opérateurs différentiels symétrisants relatifs aux systèmes non-conservatifs
Authors: Abdi R El , Gambart G 
Published: April 2011

For nonconservative systems, which we call systems with follower loads, a study is proposed concerning the differential operators which lead to a self-adjoint problem for a generalization of the Rayleigh quotient.In the case of punctual loads, we give the general expression for the identification of these operators. For some systems under follower loads, a new method is developed for the identification of the eigenvalues (critical load and critical frequency) when these operators do not exist. A numerical comparison is presented when the exact solutions do exist. PACS Nos. : 02.00 et 03.00
Article
Authors: Bunge C F , J'auregui R , Ley-Koo E 
Published: April 2011

When the one-body part of the relativistic Hamiltonian H is asum of one-electron Dirac Hamiltonians, relativistic configurationinteraction (CI) calculations are carried out on an ad hocbasis of positive-energy orbitals, {u+j; j=1,2,...,m}, andmore recently, with the full bases of positive-energy andnegative-energy orbitals, {u+j ,u-j ;j=1,2,...,m}. Therespective eigenproblems,H+C+k=E+kC+k, k=1,2,..., N(m),andHCk=EkCk ; k=1,2,...,N(2m)are related throughE+k <= Ek+N(2m)-N(m)establishing a new variational principle for relativistic calculationsof electronic structures.In this paper, on the basis of Brillouin's theorem and a relativisticmulticonfiguration Hartree-Fock (RMCHF) expansion in the{u+j, u-j; j=1,2,...,m} basis, we develop equations to annihilatethe coefficients of all single excitations to obtain very accurateRMCHF solutions.Moreover, after nullifying the coefficients of single excitations,the above inequality among energies becomes an equality,leading to a particular instance of an exact decoupling ofpositive-energy and negative-energy orbitals, irrespective of anyad hoc choice of potentials, hence rigorously justifying, forthe first time, the absence of explicit projection operators in allcurrent relativistic work where one-electron Dirac Hamiltoniansare involved.We present, also for the first time, relativistic Hartree-Fockapproximations for the ground states of He through Ar, which areaccurate to six decimals in a.u., and which converge to thenonrelativistic results when the speed of light c -> infinity.This accuracy was obtained by means of compact Slater-type orbitalexpansions through a direct translation of nonrelativistic Hartree-Fockwithout need to reoptimize nonlinear parameters. Our SCFequations are also valid for any open shells and for anyexcited states within a given symmetry, as exemplified withapplications to odd-parity, J = 1/2, 1s22s22p2np statesof neutral nitrogen. PACS Nos.: 31.10+z, 11.80Fv, 31.20Tz, 31.30Jv
Ultrashort-pulse generation by self-mode-locked Ti:sapphire lasers without apertures and with low pumping powers
Authors: Hajiesmaeilbaigi Fereshteh , Azima Ahmad 
Published: April 2011

We demonstrate the low-pump-power operation of a self-mode-locked Ti:sapphirelaser without hard apertures.The pump power was reduced owing to the tight focusing geometryin our design. Stable sub-25-fs duration pulses for pump powers in the range 2.83.0 W for the10 mm long Ti:sapphire crystal, and sub-15-fs duration pulses for pump powers in the range0.50.6 W for the 2 mm crystal were obtained. PACS No.: 42.60
High-algebraic, high-phase lag methods for accurate computations for the elastic- scattering phase shift problem
Authors: Simos T E 
Published: April 2011

A family of three new hybrid eighth-algebraic-order two-step methods with phase lag of order 16, 18, and 20 are developed for computing elastic-scattering phase shifts of the one-dimensional Schrödinger equation. Based on these new methods, we obtain some new embedded variable-step procedures for the numerical integration of the Schrödinger equation. Numerical results obtained for both the integration of the phase-shift problem for the well known case of the LennardJones potential and the integration of coupled differential equation arising from the Schrödinger equation show that these new methods are better than other finite-difference methods. PACS Nos.: 02.00, 02.70, 03.00, 03.65
The powder Zeeman study of CH3NH3Hg2Cl5 by the nuclear quadrupole resonance
Authors: Saygin Neslihan 
Published: April 2011

The temperature dependence of the Cl nuclear quadrupole resonance (NQR) frequency in CH3NH3Hg2Cl5 was investigated for temperatures between 77 and 340 K where three frequencies were found. The Zeeman effect on the NQR of 35Cl in a crystalline powder of CH3NH3Hg2Cl5 was studied. The asymmetry parameter (η) of the electric field gradient for the second frequency was obtained. PACS No.: 33.25
Review / Sythèse Nonlinear acoustic applications for material characterization: A review
Authors: Zheng Y , Maev R Gr , Solodov I Yu 
Published: April 2011

The nonlinear acoustic applications for material characterization are reviewed. The general theoretical analysis of the effects of nonlinearity, dissipation, dispersion, and diffraction on intense acoustic-wave propagation is given. Acoustic nonlinear parameters and their determination methods are introduced. The investigations of nonlinear acoustic applications for solid material evaluation are discussed for different levels of disruption, from asymmetry of lattice structure and dislocation in crystals to disbonds and cracks in engineering materials. The experimental methods involved in these investigations are also considered. The techniques used for nonlinear acoustic imaging are divided into two categories, concerned with resolution improvement by using higher harmonics, and nonlinear parametric imaging. The nonlinear acoustic applications in biomedical imaging, acoustic microscopy, and nonlinear nondestructive evaluation are presented. Finally, the issues that need further investigations in this area are discussed. PACS Nos.: 43.25, 62.65, 62.20M
Pulmonary and systemic vascular tissue collagen, growth factor, and cytokine gene expression in the rabbit
Authors: Belik Jaques , Karpinka Brad , Hart David A 
Published: April 2011

During development, the vascular wall composition of the pulmonary and systemic capacitance vessels and their intravascular pressure changes. Little is known, however, about the factors controlling vascular collagen gene expression in both circulations during growth and development. The purpose of this study was to compare the developmental changes in collagen, major growth factors, and cytokines gene expression, in order to ascertain whether a circulation specific pattern is present in the rabbit. Fetal, neonatal, and adult rabbit extrapulmonary and aortic tissues were obtained and the mRNA levels for collagen I and III, as well as major growth factors and cytokines, were measured by a semi-quantitative RT-PCR technique. Collagen I, but not collagen III, expression was developmentally regulated in pulmonary vascular and aorta tissues. Collagen I expression was greatest during the fetal and neonatal period (P < 0.01) and higher in the aorta as compared with the pulmonary artery at these ages (P < 0.05). Significant developmental changes in growth factor mRNA levels were observed for TGF-beta, IGF-2, and bFGF (P < 0.01). IGF-2 mRNA levels significantly declined in both arteries from neonatal to adult, but bFGF increased only in the pulmonary artery during this transition. With regards to inducible enzymes, COX-2 mRNA levels changed developmentally, whereas iNOS mRNA levels were similar for both vessels at all ages. When comparing the two vessels, COX-2 transcripts were relatively more abundant in the adult pulmonary artery tissue and fetal aorta, with similar levels in the newborn. We conclude that circulation specific developmental regulation of collagen gene expression is present in the rabbit in a pattern that is unrelated to the intravascular pressure.Key words: developmental changes, vascular, collagen, mRNA expression, growth factors.
Bethanechol and N-acetylcysteine mimic feeding signals and reverse insulin resistance in fasted and sucrose-induced diabetic rats
Authors: Lautt W. Wayne , Schafer Joshua , Macedo M. Paula , Legare Dallas J. 
Published: April 2011

Meal-induced insulin sensitization (MIS) is explained by the HISS (hepatic insulin sensitizing substance) hypothesis. In the presence of two “feeding signals,” a pulse of insulin results in the release of HISS from the liver. HISS acts selectively on skeletal muscle and doubles the response to insulin. HISS is not released in the fasted state or in the sucrose-supplemented diabetes model. We tested the hypothesis that provision of both feeding signals allows insulin to cause HISS release in both the normal fasted and the diabetic model. The dynamic response to insulin (50 mU/kg over 5 min) was quantified using the rapid insulin sensitivity test (RIST). Gastric injection of a liquid test meal or i.v. administration of N-acetylcysteine in 24 h fasted rats raised hepatic glutathione to a similar degree (by 46%–47%). Hepatic denervation in fed rats eliminated the parasympathetic signal and eliminated MIS, and bethanechol completely restored MIS. Both compounds administered together allowed insulin to stimulate HISS release in 24 h fasted rats and in a diabetic model (9-week, 35% liquid sucrose supplement). Neither was effective alone. Both “feeding signals” are necessary and sufficient for insulin to stimulate HISS release.