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Purpose Size-specific dose estimates (SSDEs) are the latest focus of interest among medical physicists studying radiation dose to the patient in computed tomography (CT). This study aims to make conversions from CTDIvol to SSDE and investigate the relationship between mean SSDE (SSDE) and central SSDE (SSDEcenter) values for pediatric patients of different age groups undergoing chest, abdomen, and pelvis scans. Methods In this retrospective study, we examined 105 consecutive pediatric CT exams of chest, abdomen, and pelvis (CAP) classified in 3 separate groups according to age: 0-5 years, 6-10 years, and 11-16 years. A MATLAB program was developed to determine SSDE values for each patient along 6 subregions: chest, abdomen, pelvis, chest and abdomen, abdomen and pelvis, and CAP. SSDE values derived over the slice at the center of each scan range (SSDEcenter) were also recorded. SSDE and corresponding SSDEcenter results were compared for each age group. Results Root mean square differences (RMSD) between SSDE and SSDEcenter values ranged between 0.13 mGy and 2.1 mGy through all groups and subregions, corresponding to 1.2% and 11%, respectively. Conclusion In pediatric CT exams involving CAP region, CTDIvol and the water equivalent diameter at the middle of the scan range can be used to provide a reasonable estimate of mean SSDE with an RMSD of 11% at most.

WOS: 000271864200007, Valence band structure with spin-orbit (SO) coupling of GaAs/Ga1-xAlxAs square quantum well (SQW) under the electric field by a calculation procedure based on a finite element method (FEM) is investigated using the multiband effective mass theory ((k) over right arrow . (p) over right arrow method). The validity of the method is confirmed with the results of D. Ahn, S. L. Chuang and Y. C. Chang (J. Appl. Phys. 64 (1998) 4056), who calculated valence band structure, using axial approximation for Luttinger-Kohn Hamiltonian and finite difference method. Our results demonstrated that SO coupling and electric field have significant effects on the valence band structure., T. R. Prime Ministry State Planning Organization [DPT-120220], The authors would like to thank the T. R. Prime Ministry State Planning Organization for financial support (project No. DPT-120220).

State-selective differential cross sections for single-electron capture processes in very slow collisions of Arq+ (q = 4–6) ions with neon (Ne) have been studied experimentally at laboratory impact energies between 0.4 and 4 qeV/amu and scattering angles between 0 ° and 8 ° by means of the translational energy-gain spectroscopy technique. The translational energy spectra show that the dominant reaction channels are due to capture into excited states of the projectile product Ar(q−1)+. However, at very low energies, other channels due to transfer excitation processes are found to open at large scattering angles. The energy-gain spectra are interpreted qualitatively in terms of the reaction windows, which are calculated using the single-crossing Landau-Zener model and the extended version of the classical over-the-barrier model. The energy dependence of cross sections for single-electron capture by Arq+ (q = 4–8) ions from Ne are also measured and found to be nearly constant with changing impact energy, but increase with an increase in the projectile charge state. The data are also compared with available measurements and theoretical calculations. Copyright © 1999 John Wiley & Sons, Ltd.

IntroductionVolumecomputed tomography dose index(CTDIvol) does not contain any dose information regarding the patient size. Size specific dose estimates (SSDE) give more reliable results accounting for the patient size as well. This parameter uses CTDIvol and size dependent conversion factors (fDw) which are calculated by means of water equivalent diameter (Dw) of the patient cross section in every slice of image.PurposeTo develop software to automatically calculate SSDE and to assess the impact of variations in Dw along the z axis on SSDE for CT examinations of the torso in pediatric patients.Materials and methods55 consecutive CT exams of the combined chest, abdomen and pelvis (CAP) have been examined. SSDE has been calculated for 6 hypothetical scan ranges: chest alone, abdomen alone, pelvis alone, chest and abdomen, abdomen and pelvis, and CAP. Two methods were used in mean SSDE approach: (1) mean SSDE over each scan range; (2) SSDE value at the middle of the scan range.ResultsFor scan ranges 1 to 6, the average of the difference in maximal and minimal Dw accross patients was 3.7, 3.8, 2.6, 4.1, 4.4 and 4.5 cm. The mean SSDE values calculated using methods (1) and (2) were highly compatible, with root mean square differences of 0.4, 0.5, 0.3, 1.0, 1.5 and 0.7mGy or 3%, 4%, 2%, 7%, 10%, 5%.ConclusionUsing the mean CTDIvol and the water equivalent diameter at the middle of the scan range provides a reasonable estimation of patient dose in pediatric exams.

In this work we solve thermo-hydrodynamical equations considering a two dimensional electron system in the integer quantum Hall regime, to calculate the spatial distribution of the local electron temperature. We start from the self-consistently calculated electrostatic and electrochemical potentials in equilibrium. Next, by imposing an external current, we investigate the variations of the electron temperature in the linear-response regime. Here a local relation between the electron density and conductivity tensor elements is assumed. Following the Ohm's law we obtain local current densities and by implementing the results of the thermo-hydrodynamical theory, calculate the local electron temperature. We observe that the local electron temperature strongly depends on the formation of compressible and incompressible strips., Comment: 10 pages, 4 figures

WOS: 000268802300062, In this work, we propose an efficient method of reducing the computational effort of variational calculation with a Hylleraas-like trial wavefunction. The method consists of introducing integra transforms for the terms as r(12)(k) exp (-lambda r(12)) which provide the calculation of the expectation value of energy and the relevant matrix elements to be done analytically over single-electron coordinates instead of Hylleraas coordinates. we have used this method to calculate the ground state energy of a two-electron system in a spherical dot and a disk-like quantum dot separately. Under parabolic confinement potential and within effective mass approximation size and shape effects of quantum dots on the ground state energy of two electrons have been investigated. The calculation shows that our results even with a small number of basis states are in good agreement with previous theoretical results., Cumhuriyet University; National MOVPE Crystal Growth and Characterization Laboratory, Turkey [DPT-K 120]; TUBITAK [TBAG 105T492, TBAG 107T012, TBAG-108T015], Project supported by the Cumhuriyet University, National MOVPE Crystal Growth and Characterization Laboratory, Turkey, DPT-K 120, TUBITAK (Grant Nos TBAG 105T492, TBAG 107T012, and TBAG-108T015).

The title compound, C16H17NO2, was found to crystallize in the triclinic space group P1. The unit cell parameters are: a = 8.279(1)A, b = 14.843(2)A, c = 5.959(1)A, α = 97.02(1)°, β = 102.75(1)°, γ = 100.52(1)°; Z = 2. The molecule is not planar. The ethoxy group is almost coplanar with the ethoxyphenyl ring, the hydroxy group and the central moiety of the molecule are almost in the hydroxyphenyl ring plane. The dihedral angle between the two planes is 65.4(1)°. The crystal structure is stabilized by weak intermolecular interactions of the C-H···O type.

Double differential cross sections for state-selective single-electron capture processes in Ar6+-He collisions have been measured at laboratory energies between 75 and 900 eV and scattering angles between 0 and 8 degrees. At the lowest energy, the zero-angle spectrum shows capture into Ar5+(4p) to be the most important channel. However,as the scattering angle is increased, a second peak appears at angles greater than or equal to 2 degrees and becomes more pronounced relative to the 4p capture channel. The energy spectra are interpreted qualitatively in terms of the reaction windows, which are calculated using the single-crossing Landau-Zener model Total and differential cross sections are also measured and compared with available measurements and calculations.