An anatomical study in a Chinese population of the position of the rib head for placing anterior vertebral body screws

The instrumentation of anterior vertebral body screws has become an important approach for the treatment of unstable fractures or curvature of the spine, but little attention has been paid to the starting point of placing the screws and the variability of the rib head position. We analysed the variability of rib head position in a Chinese population in terms of the spinal canal and vertebral body using computed tomography (CT). Images from transverse CT scans of the T4–T12 vertebral bodies of 30 normal individuals were 3-D reconstructed and analysed for measurement of parameters which included: 1) distance between the left (or right) anterior border of the rib head and the posterior (or anterior) margin of the vertebral body [L(R)ARHP(A)VB]; 2) left (or right) transverse dimension [L(R)TD]; 3) left (or right) posterior (or anterior) safe angle [L(R)P(A)SA]; and 4) distance between the inferior border of the left (or right) rib head and the superior (or inferior) end-plate in the sagittal plane [I L(R)RHS(I)EP]. The ARHPVB, PSA, and IRHIEP gradually decrease, but ARHAVB, TD, ASA, and IRHSEP gradually increase, from T4 to T12, indicating that the position of the rib head changes from a more anterior position to a more posterior position and from a more superior position to a more inferior position, as the number of the vertebra increases. Our study has provided a comprehensive reference guide for accurate and safe instrumentation of vertebral body screws in treating related spine diseases. (Folia Morphol 2010; 69, 4: 232-240

Acoustic phonon transport through a double-bend quantum waveguide

In this work, using the scattering matrix method, we have investigated the transmission coefficients and the thermal conductivity in a double-bend waveguide structure. The transmission coefficients show strong resonances due to the scattering in the midsection of a double-bend structure; the positions and the widths of the resonance peaks are determined by the dimensions of the midsection of the structure. And the scattering in the double-bend structure makes the thermal conductivity decreases with the increasing of the temperature first, then increases after reaches a minimum. Furthermore, the investigations of the multiple double-bend structures indicate that the first additional double-bend structure suppresses the transmission coefficient and the frequency gap formed; and the additional double-bend structures determine the numbers of the resonance peaks at the frequency just above the gap region. These results could be useful for the design of phonon devices.Comment: 13 pages, 6 figures, elsart.cls is use

BES3 time of flight monitoring system

A Time of Flight monitoring system has been developed for BES3. The light source is a 442-443 nm laser diode, which is stable and provides a pulse width as narrow as 50 ps and a peak power as large as 2.6 W. Two optical-fiber bundles with a total of 512 optical fibers, including spares, are used to distribute the light pulses to the Time of Flight counters. The design, operation, and performance of the system are described.Comment: 8 pages 16 figures, submitted to NI

Experimental Study and Finite Element Analysis of Critical Stresses of Reinforced Thermoplastic Pipes under Various Loads

In this paper, reinforced thermoplastic pipes (RTP) were studied under various loads. A total of five groups of specimens were designed to study the mechanical properties of RTPs under internal pressure, bending, a combination of internal pressure and bending moment, external pressure, and tension. This study obtained the bursting pressure of RTPs under internal pressure, the minimum bending radius under the bending moment, and the failure pressure under external pressure. At the same time, the mechanical properties of RTPs under various loads were analyzed using the finite element analysis. Analytical results agree well with the experimental ones. The finite element model established in this paper can be used for further research on the mechanical properties of RTPs

Revisiting the B {\to} {\pi} {\rho}, {\pi} {\omega} Decays in the Perturbative QCD Approach Beyond the Leading Order

We calculate the branching ratios and CP asymmetries of the $B \to \pi \rho$, $\pi\omega$ decays in the perturbative QCD factorization approach up to the next-to-leading-order contributions. We find that the next-to-leading-order contributions can interfere with the leading-order part constructively or destructively for different decay modes. Our numerical results have a much better agreement with current available data than previous leading-order calculations, e.g., the next-to-leading-order corrections enhance the $B^0\rightarrow \pi^0\rho^0$ branching ratios by a factor 2.5, which is helpful to narrow the gaps between theoretic predictions and experimental data. We also update the direct CP-violation parameters, the mixing-induced CP-violation parameters of these modes, which show a better agreement with experimental data than many of the other approaches.Comment: 23 pages, 4 figures, 4 table

Larmor precession and tunneling time of a relativistic neutral spinning particle through an arbitrary potential barrier

The Larmor precession of a relativistic neutral spin-1/2 particle in a uniform constant magnetic field confined to the region of a one-dimensional arbitrary potential barrier is investigated. The spin precession serves as a clock to measure the time spent by a quantum particle traversing a potential barrier. With the help of general spin coherent state it is explicitly shown that the precession time is equal to the dwell time.Comment: 10 pages, 1 figure. To be published in Phys. Rev. A (01 February 2002