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The paper deals with the method of tool path generation for 5-axis control machining using a ball end mill. 5-axis control machining has been used for aircraft parts as well as for complicated shapes such as mold and dies. However, most of the present CAM systems for 5-axis control machining have limited functions in terms of tool collision, workpiece shapes and machining methods. For that reason, in many cases the optimal cutter location (CL) data cannot be obtained or considerable time is consumed. To solve this problem, we applied a 3-dimensional configuration space (C-Space) and showed the relationship between all tool positions and postures and the existence of tool collision. The method of tool path generation devised in the study enables users to generate CL data reflecting their own machining strategy such as smooth change in tool posture and the state of machining without considering the gouging. The validity of this method was experimentally confirmed by successfully milling an impeller without tool collision occurring.

Objectives: Pre‐exposure prophylaxis (PrEP) for HIV infection is an important intervention for control of the HIV epidemic. The incidence of HIV infection is increasing in the countries of Central and Eastern Europe (CEE). Therefore, we investigated the change in PrEP use in CEE over time. Methods: The Euroguidelines in Central and Eastern Europe (ECEE) Network Group was initiated in February 2016 to compare standards of care for HIV and viral hepatitis infections in CEE. Data on access to PrEP were collected from 23 countries through online surveys in May–June 2017 (76 respondents) and in November 2018–May 2019 (28 respondents). Results: About 34.2% of respondents stated that tenofovir/emtricitabine (TDF/FTC) was licensed for use in their country in 2017, and 66.7% that it was licensed for use in 2018 (P = 0.02). PrEP was recommended in national guidelines in 39.5% of responses in 2017 and 40.7% in 2018 (P = 0.378). About 70.7% of respondents were aware of "informal" PrEP use in 2017, while 66.6% were aware of this in 2018 (P = 0.698). In 2018, there were 53 centres offering PreP (the highest numbers in Poland and Romania), whereas six countries had no centres offering PreP. The estimated number of HIV‐negative people on PreP in the region was 4500 in 2018. Generic TDF/FTC costs (in Euros) ranged from €10 (Romania) to €256.92 (Slovakia), while brand TDF/FTC costs ranged from €60 (Albania) to €853 (Finland). Conclusions: Although the process of licensing TDF/FTC use for PrEP has improved, this is not yet reflected in the guidelines, nor has there been a reduction in the "informal" use of PrEP. PrEP remains a rarely used preventive method in CEE countries. [ABSTRACT FROM AUTHOR]

Byline: K. Shimada, N. Mori, T. Kondo, T. Itoh, K. Kase, A. Makinouchi This paper presents a fully automated meshing scheme suitable for sheet forming simulation. We adopt a new meshing procedure, called 'bubble meshing', to create a graded quadrilateral mesh. In this method, a set of nodes is first distributed by closely packing spheres, or 'bubbles', in a domain, adjusting the sphere sizes by the three indicators of strain gradient, curvature and contact condition. A well-shaped triangular mesh is then created by connecting the centres of these bubbles or nodes. Finally, the triangular mesh is preserved. It is shown that the method satisfies fundamental meshing requirements for sheet metal forming simulation, such as precise element size control and mesh adaptivity.

SUMMARY A three-dimensional Cartesion cut cell method is presented for the simulations of incompressible viscous flows with irregular domains. A new model (referred to as '6+ N' model) is proposed to describe arbitrarily shaped cut cells and treat all the cells as polyhedrons with 6+ N faces. The finite volume discretization of the Navier-Stokes equation is then implemented by using the '6+ N' model to separate the surface flux integrals into two parts, that is, the fluxes through the basic face of the hexahedron and those through the cutting surfaces. The previously proposed Kitta Cube algorithm and volume computer-aided design platform ( J. Comput. Aided. Des. 2005; 37(4): 1509-1520. Doi:10.1016/j.cad.2005.03.006) are adopted to generate cut cells and provide shape data and physical attributes for the numerical analysis. A modified SIMPLE-based smoothing pressure correction scheme is applied to suppress checkerboard pressure oscillations caused by the collocated arrangement of velocities and pressure. The calculation accuracy of the numerical method expressed by L1 and L ∞ norm errors is first demonstrated by the simulation of a pipe flow. Then its feasibility, efficiency, and potential in engineering applications are verified by applying it to solve natural convections between concentric spheres and between eccentric spheres. The heat transfer patterns in eccentric spheres are also obtained by using the numerical method. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A new scanning transmission electron microscope has been developed for three-dimensional (3D) observations of nanostructures. Using double spherical fulcra, accurate eucentric rotation was achieved. Cylindrical specimens for 3D-observation were prepared by a microsampling technique using a focused ion beam. Copper via-holes of a semiconductor memory device and ZnO particles were observed by the 3D-STEM from different directions, and 3D-data of the ZnO particles were successfully reconstructed in a topography mode. [ABSTRACT FROM PUBLISHER]

An abstract of the article "Ionizing Radiation Exposure of the U.S. Population," by K. R. Kase, M. Rosenstein, K. L. Miller, D. M. Quinn, D. J. Strom, O. Suleiman and B. R. Thomadsen is presented.

We have simulated the head geometry of a Varian Clinac 2100C/2300C medical accelerator in a Monte Carlo calculation to produce photoneutrons and transport them through the head shielding into a typical therapy room (modeled by a test cell at Varian Associates). The fast neutron leakage fluence and energy spectra have been calculated at 7 positions around the linac head for typical beam operation at 10, 15, 18 and 20 MV. The results of these calculations have been compared with limited measurements made using the same model accelerator operating in a Varian test cell. Calculations were also made for the fluence and energy spectra outside the head with no surrounding concrete walls,floor or ceiling to eliminate the effects of scattering from concrete. Comparisons were also made with calculations using a much simplified head geometry. The results indicate that the calculations using the complex head geometry compare, within the uncertainties, with the measurements. The simple head geometry leads to differences of a factor of 2 from the complex geometry. Results of these calculations can be used to calculate fast neutron transmission through various shielding configurations and through labyrinths. [ABSTRACT FROM AUTHOR]

The photoneutron yields produced in different components of the medical accelerator heads evaluated in these studies (24-MV Clinac 2500 and a Clinac 210OC/2300C running in the 10-MV, 15-MV, 18-MV and 20-MV modes) were calculated by the EGS4 Monte Carlo code using a modified version of the Combinatorial Geometry of MORSE-CG. Actual component dimensions and materials (i.e., targets, collimators, flattening filters, jaws and shielding for specific accelerator heads) were used in the geometric simulations. Calculated relative neutron yields in different components of a 24-MV Clinac 2500 were compared with the published measured data, and were found to agree to within q30%. Total neutron yields produced in the Clinac 2100/2300, as a function of primary electron energy and field size, are presented. A simplified Clinac 2100/2300C geometry is presented to calculate neutron yields, which were compared with those calculated by using the fully-described geometry. [ABSTRACT FROM AUTHOR]

Detailed petrographic and microprobe studies of micronodules identified in the manganese carbonate orebody and adjacent Mn-rich rocks at the ∼2.2 Ga Nsuta deposit, Ghana, indicate distinct lithologic control on nodule structure and chemical composition. Nodules in the Mn-rich rocks adjacent to the manganese carbonate orebody conform with the well-banded nature of the rock and are distinctly zoned into alternating bands compositionally dominated by Mg kutnahorite and Mg–Ca rhodochrosite. Individual nodules are partially or completely cemented by thin dark silica and carbonates of Ca–Mg±Mn solid solution. Nodules in the orebody, on the contrary, are generally massive, homogeneous, consist predominantly of rhodochrosite and are only partially cemented by dark silica. Based on the stratigraphic relationship of the nodule-bearing rocks to the manganese carbonate orebody and the variations in texture and composition observed in the nodules, it would appear that the Mn carbonate nodules precipitated diagenetically in response to changing pore water chemistry and/or metal (Mn and Ca) supply. The overall mineralogical and geochemical features indicate, in addition, that the nodules may have preserved original carbonate compositions, both metastable and stable, during burial diagenesis and low-grade regional metamorphism. [Copyright &y& Elsevier]