Ternary Z2 × Z3 Graded Algebras and Ternary Dirac Equation

The wave equation generalizing the Dirac operator to the Z₃-graded case is introduced, whose diagonalization leads to a sixth-order equation. It intertwines not only quark and anti-quark state as well as the u and d quarks, but also the three colors, and is therefore invariant under the product group Z₂ × Z₂ × Z₃. The solutions of this equation cannot propagate because their exponents always contain non-oscillating real damping factor. We show how certain cubic products can propagate nevertheless. The model suggests the origin of the color SU(3) symmetry and of the SU(2) × U(1) that arise automatically in this model, leading to the full bosonic gauge sector of the Standard Model.

     

Update on two-zero textures of the Majorana neutrino mass matrix in light of recent T2K,Super-Kamiokande and NOνA results

The latest results from atmospheric and accelerator neutrino experiments indicate that the normal neutrino mass ordering m_1 m_2 m_3, a maximal leptonic CP-violating phase δ = 270° and the second octant of neutrino mixing angle θ_23 45° are favored. In light of new experimental results, we update previous phenomenological studies on two-zero textures of the Majorana neutrino mass matrix M-_ν, in the flavor basis where the charged-lepton mass matrix M_l is diagonal. When the 1σ ranges of neutrino mixing parameters are taken into account, only four(i.e., A_(1,2)and B_(2,4)) among seven two-zero patterns of Mνshow the aforementioned features of neutrino mass spectrum, mixing angle θ_23and CP-violating phase δ, and thus are compatible with the latest neutrino oscillation data. The correlative relations among neutrino masses and mixing parameters have been derived analytically for these four patterns, and the allowed regions of neutrino mixing angles and the CP-violating phase are also given. Possible realizations of four viable two-zero textures via non-Abelian discrete flavor symmetries are discussed.     

2D/3D CFETR����ҵ�ż���

基于ANSYS对CFETR真空室简化模型进行了2D/3D电磁分析,得到了真空室磁场强度以及电磁力的分布.分析结果显示2D/3D真空室的磁场强度及电磁力分布基本一致,这表明了可以使用2D模型替代3D模型对未来真空室简化模型进行电磁分析.     

Adsorption of Perylene on Si(111)(7×7)

We investigate the adsorption of organic molecular semiconductor perylene on(7 × 7) reconstructed Si(111)surface by ultraviolet photoemission spectroscopy.It is observed that seven features that derive from the organic material are located at 0.71,2.24,4.0,5.9,7.46,8.65 and 9.95 eV in binding energy.The theoretical calculation results reveal the most stable adsorption geometry of organic molecule perylene on Si(111)(7 × 7) substrates is at the beginning of deposition.     

Quasi-Classical Trajectory Study on Ar＋H2＋/D2＋/T2＋ Reactions

In order to explore the isotope effect on stereo dynamics, we investigate the trajectory calculations of Ar＋H2＋/D2＋/T2＋ and Ar＋T2＋ reactions on the ab initio potential energy surface constructed by us and calculate the distributions of product polarization P（θr）, P（r） and four generalized polarization-dependent differential cross-sections. The product rotational alignment parameters （P2（j＇ · k）） for the title reactions are compared and discussed with mass factors. Furthermore, the angular distributions of the product rotational vectors in the form of polar plot in θr and r are presented. The results indicate that the stereo dynamics properties of the title reactions are sensitive to the mass factor.     

Calculation of the Isotope Shifts on 5S1/2 → 4D3/2,5/2 Transitions of 87,88Sr+

A simple method is applied to calculating the isotope shifts (ISs) on 5S1/2 → 4D3/2,5/2 transitions of 87,88Sr+. First we have calculated the ISs of lower transitions on a series of alkali-like systems such as B2+, Ca+ and Ba+, which are in agreement with other works. Then the ISs on 5S1/2 → 4D3/2,5/2 transitions of 87,88Sr+, which are useful to study the Sr+ optical frequency standard, are evaluated.     

Determination of Chemical Effect on the Kβ1/Kα, Kβ2/Kα, Kβ2/Kβ1 and Kβ/Kα X-Ray Intensity Ratios of 4d Transition Metals

It is clear that detailed studies performed under identical experimental conditions are desirable to determine the effect of the chemical environment on the value of intensity ratios. To better understand this effect, we conducted measurements on Kβ₁/Kα, Kβ₂/Kα, Kβ₂/Kβ₁ and Kβ/Kα x-ray intensity ratios. The Kα and Kβ_1,2 emission spectra for compounds of 4d transition metals Y, Zr, Nb, and Mo were measured using a Si(Li) solid-state detector. The samples were excited by 22.69 keV x-rays emitted from a ¹⁰⁹Cd radioisotopes source. The experimental results for pure elements are compared with the other experimental and theoretical values.     

Decays of T Z = − 3/2 nuclei 23Al, 31Cl, and 41Ti

This article gives an overview on the decay spectroscopy of T _Z ?=???3/2 nuclei ²³Al, ³¹Cl, and ⁴¹Ti performed at the Ion Guide Isotope Separator On-Line (IGISOL) facility. The results of the IGISOL experiments are compared to the experimental results that have been published since. The isobaric multiplet mass equation (IMME) has been studied for the T?=?3/2 quartets at A?=?23 and A?=?31. For ⁴¹Ti, a detailed comparison to the Gamow–Teller strengths obtained for the analog transitions via charge-exchange reactions has been done. Further improvements in the experimental instrumentation and methods and possible implementations for studying T _Z ?=???3/2 nuclei at the new IGISOL facility are discussed.     

Clinical feasibility of 3D-QALAS – Single breath-hold 3D myocardial T1- and T2-mapping

PurposeTo investigate the in-vivo precision and clinical feasibility of 3D-QALAS - a novel method for simultaneous three-dimensional myocardial T1- and T2-mapping.MethodsTen healthy subjects and 23 patients with different cardiac pathologies underwent cardiovascular 3 T MRI examinations including 3D-QALAS, MOLLI and T2-GraSE acquisitions. Precision was investigated in the healthy subjects between independent scans, between dependent scans and as standard deviation of consecutive scans. Clinical feasibility of 3D-QALAS was investigated for native and contrast enhanced myocardium in patients. Data were analyzed using mean value and 95% confidence interval, Pearson correlation, Paired t-tests, intraclass correlation and Bland-Altman analysis.ResultsAverage myocardial relaxation time values and SD from eight repeated acquisitions within the group of healthy subjects were 1178 ± 18.5 ms (1.6%) for T1 with 3D-QALAS, 52.7 ± 1.2 ms (2.3%) for T2 with 3D-QALAS, 1145 ± 10.0 ms (0.9%) for T1 with MOLLI and 49.2 ± 0.8 ms (1.6%) for T2 with GraSE.Myocardial T1 and T2 relaxation times obtained with 3D-QALAS correlated very well with reference methods; MOLLI for T1 (r = 0.994) and T2-GraSE for T2 (r = 0.818) in the 23 patients. Average native/post-contrast myocardial T1 values from the patients were 1166.2 ms/411.8 ms for 3D-QALAS and 1174.4 ms/438.9 ms for MOLLI. Average native myocardial T2 values from the patients were 53.2 ms for 3D-QALAS and 54.4 ms for T2-GraSE.ConclusionsRepeated independent and dependent scans together with the intra-scan repeatability, demonstrated all a very good precision for the 3D-QALAS method in healthy volunteers. This study shows that 3D T1 and T2 mapping in the left ventricle is feasible in one breath hold for patients with different cardiac pathologies using 3D-QALAS.     

STM study of nucleation of Ag on Si(111)−(7 × 7) surface

Initial stages of Ag on Si(111)−(7 × 7) surface nucleation were studied at submonolayer coverage. Samples were prepared by thermal evaporation of Ag from tungsten wire under UHV conditions (p<2.5 × 10⁻⁸ Pa). Various deposition rates (0.002–0.1 ML s⁻¹) were used to prepare Ag island films with coverages (0.002–2) ML (1 ML ≈ 7.58 × 10¹⁴ atoms cm⁻²) at room temperature. We observed preferential growth on faulted half unit cells (F cells). At constant coverage both the island density and ratio of occupied F and U (unfaulted) cells are independent of the deposition rate, which is an evidence for dominant influence of substrate structure. The preference of nucleation in the F cells against U cells decreases with the coverage until the ratio is 1:1 for 1 ML Ag film. We have observed that presence of an Ag island in any type of the half unit cell (F or U) considerably reduces nucleation probability in neighbouring cells. This results in forming of structural patterns observed among randomly grown Ag-islands which is a new feature found for Ag/Si(111)−(7 × 7) system. Presented at the VIII-th Symposium on Surface Physics, Třešt’ Castle, Czech Republic, June 28 – July 2, 1999. This work was supported by the Grant Agency of Charles University — projects GAUK 34/97 and 147/99, by the Grant Agency of Czech Republic — project GAČR 202/97/1109 and by the Ministry of Education grant VS 97116.     

2D/3D CFETR真空室电磁计算

基于ANSYS对CFETR真空室简化模型进行了2D/3D电磁分析,得到了真空室磁场强度以及电磁力的分布。分析结果显示2D/3D真空室的磁场强度及电磁力分布基本一致,这表明了可以使用2D模型替代3D模型对未来真空室简化模型进行电磁分析。     

Diffusion of Au atoms and (5×2) phase formation on the Si(111) (7×7) surface

In this article we investigate the complex 1D mesoscopic model of adatom diffusion and the evolution of an ordered phase on the substrate surface. The analysis of the theoretical model is compared with the experimental results of the spreading of Au adatoms on Si(111)-(7×7) surface. The steady state solutions and their stability conditions are determined within the concept of the traveling-wave solution. It is shown that the formation of the ordered phase (5×2) and the difference in the diffusion of Au on (7×7) and on (5×2) structure results in a sharp edge of diffusion front which corresponds to the coverage of a saturated (5×2) phase. This edge moves linearly in time and α can be determined by experiment. The system of model equations enables the damped waves solution or temporary evolution of two steps.     

YBa2Cu3O7−δ /CeO2 heterostructures on sapphire R-plane

(001)YBa₂Cu₃O_7−δ epitaxial films were prepared by laser ablation on surface. A thin (001)CeO₂ or (111)CeO₂ buffer layer was deposited between the substrate and the superconductor film to reduce their chemical interaction. In the initial stages of CeO₂ buffer formation, its orientation depended strongly on the intensity of cerium ion interaction with oxygen. Epitaxial growth of (001)YBa₂Cu₃O_7−δ films was achieved both on and . The T _c temperature of epitaxial (001)YBa₂Cu₃O_7−δ films was within 88–90 K, and the current J _c at 77 K was in excess of 10⁶ A/cm⁻². Fiz. Tverd. Tela (St. Petersburg) 40, 205–208 (February 1998)     

Adsorption of O2 and CO2 on the Si(111)-7 × 7 surfaces

The interaction of O₂ and CO₂ with the Si(111)-7 × 7 surface has been studied with X-ray photoelectron spectroscopy (XPS). It was found that both O₂ and CO₂ molecules can readily oxidize the Si(111)-7 × 7 surface to form thin oxide films. Two oxygen species were identified in the oxide film: oxygen atoms binding to on-top sites of adatom/rest atoms with an O 1s binding energy of ~ 533 eV as well as to bridge sites of adatom/rest atom backbonds at ~ 532 eV. These two oxygen species can be interconverted thermally during the annealing process. Due to the low oxidation capability, the silicon oxide film formed by CO₂ has a lower O/Si ratio than that of O₂.     

Experimental study on the system of Cl/Cl_2/He/HN_3/I_2

Using a microwave generator, chlorine diluted by helium was dissociated to chlorine atoms that subsequently reacted with hydrogen azide to produce the excited states of NCl(a1△). Meanwhile, molecular iodine with carrier gas of helium reacted with atomic chlorine to produce atomic iodine which then was pumped to excited state of I(2P1/2) by an energy transfer reaction from NCl(a1△). In this paper, the changes of NCl(a1△) and NCl(b1∑) emission intensity is presented when I2/He is introduced into the stream of Cl/Cl2/He/HN3/NCl(a1△)/NCl(b1∑). The dependences of atomic iodine I(2P1/2) on flow rates of gases were also investigated. The optimum parameters for I(2P1/2) production are given.     

Study of sawtooth oscillations on the HT-7 tokamak using 2D tomography of soft x-ray signal

It is the first time so far as we know that two arrays of multi-channel soft x-ray detectors are used to generate twodimensional （2D） images of sawtooth oscillation on the HT-7 tokamak using the Fourier-Bessel harmonic reconstruction method, and using the singular value decomposition to analyse the data from soft x-ray cameras. By these two arrays, 2D image reconstruction of soft x-ray emissivity can be obtained without assumption of plasma rigid rotation. Tomographic reconstruction of the m=1 mode structure is obtained during the precursor oscillation of the sawtooth crash. The crescent-shaped mode structure appearing on the contour map of the soft x-ray emissivity is consistent with the quasiinterchange mode. The characteristics of the m=1/n=1 mode structure observed in the soft x-ray tomography are as follows： the magnetic surface is made up of the crescent-shaped “hot core” and the circular “cold bubble”. The structure of the magnetic surface rotates in the direction of the electron diamagnetic drift and the rotation frequency is the oscillation frequency of soft x-ray signals.