Three-dimensional attenuation map reconstruction using geometrical models and free-form deformations

We address the issue of using deformable models to reconstruct an unknown attenuation map of the torso from a set of transmission scans. We assume the three-dimensional (3-D) distribution of attenuation coefficients to be piecewise uniform. We represent the unknown distribution by a set of closed surfaces defining regions having the same attenuating properties. The methods of reconstruction published so far tend to directly deform the surfaces, the parameters being the surface elements. Rather than deforming the surfaces, we explore the possibility of deforming the space in which the geometrical primitives are contained. We focus on the use of free-form deformations (FFD's) to describe the continuous transformation of space used to match a set of transmission measurements. We illustrate this approach by reconstructing realistically simulated transmission scans of the torso with various noise levels and compare the results to standard reconstruction methods.     

Expression of sialyltransferase is not required for interaction of Neisseria gonorrhoeae with human epithelial cells and human neutrophils

Sialyltransferase (Stase) in Neisseria gonorrhoeae organisms (gonococci [GC]) transfers sialic acid (N-acetylneuraminic acid [NANA]) from cytidine 5'-monophospho-N-acetylneuraminic acid (CMP-NANA) mainly to the terminal galactose (Gal) residue in the Gal beta-1,4 N-acetylglucosamine (Gal-GlcNAc)-R lipooligosaccharide (LOS) structure. Sialylated GC resist killing by normal human serum, sometimes show reduced invasion of epithelial cells, and have reduced adhesion to and stimulation of human neutrophils. We questioned whether Stase itself modulates the interactions of GC with human epithelial cells and neutrophils in the absence of exogenous CMP-NANA. To that end, we treated strain F62 with ethyl methanesulfonate and grew approximately 175,000 colonies on CMP-NANA plates, and screened them with monoclonal antibody 1B2-1B7 (MAb 1B2). MAb 1B2 is specific for Gal-GlcNAc and reacts only with asialylated GC. We isolated 13 MAb 1B2-reactive mutants, including five null mutants, that had Stase activities ranging from barely detectable to fivefold less than that of wild-type (WT) F62. The LOS phenotype of Stase null mutants was identical to that of WT F62, yet the mutants could not sialylate their LOS when grown with CMP-NANA. The Stase null phenotype was rescuable to Stase+ by transformation with chromosomal DNA from WT F62. Stase null mutants remained serum sensitive even when grown with CMP-NANA. One Stase null mutant, ST94A, adhered to and invaded the human cervical epithelial cell line ME-180 at levels indistinguishable from that of WT F62 in the absence of CMP-NANA. In human neutrophil studies, ST94A stimulated the oxidative burst in and adhered to human neutrophils at levels similar to those of WT F62. ST94A and WT F62 were also phagocytically killed by neutrophils at similar levels. These results indicate that expression of Stase activity is not required for interaction of GC with human cells.     

Evolution of fission-gas-bubble-size distribution in recrystallized U-10Mo nuclear fuel

An analytical model for the nucleation and growth of intra and intergranular fission-gas bubbles, used to characterize fission-gas bubble development in U-Mo alloy fuel with burnup limited to less than 10 at.% U in order to capture the fuel swelling stage prior to irradiation-induced recrystallization, is extended to recrystallized fuel at a burnup of ∼16 at.% U. During recrystallization the grain size is transformed from micron to sub-micron sizes. The intergranular bubble-size distribution post-recrystallization is found to evolve with similar kinetics and morphology to that pre-recrystallization with any differences primarily due to gas content and initial and/or boundary conditions (e.g., fuel microstructure). The predictions of the theory are compared with measured bubble-size distributions in pre and post recrystallized U-10Mo alloy fuel.     

CMOS and SiGe bipolar circuits for applications up to 110 GHz

Recently, CMOS has been demonstrated to be a viable technology for very-high-bit-rate broad-band and wireless communication systems up to 40 Gb/s and 50 GHz. Advances in device scaling and doping-profile optimization have also resulted in SiGe bipolar transistors with impressive performance, including cut-off frequencies of more than 200 GHz. This paper presents advances in circuit design which fully exploit the high-speed potential of a 0.13 µm CMOS technology up to 50 GHz and of a high-performance SiGe bipolar technology up to 110 GHz operating frequency. The combination of advanced circuit techniques and a state-of-the-art fabrication-process technology results in continuing the upward shift of the frequency limits.     

20 Gbit/s transimpedance preamplifier and modulator driver in SiGebipolar technology

A transimpedance preamplifier and a modulator driver used in a 20 Gbit/s fibre-optic TDM transmission system are presented. The ICs were fabricated in an advanced SiGe bipolar technology. The amplifier is noted for its high gain (58 dBΩ) and low equivalent input noise current density (≃12 pA/√Hz) and the driver for its high output voltage swing (2.3 V single-ended, 4.6 V differential)     

Designing and validating a measure of moral judgment: Stage preference and stage consistency approaches.

The Defining Issues Test (DIT) of moral judgment is discussed in light of the recent challenge by C. Lind (1995) with the Moral Judgment Test (MJT), which is widely used in Europe. The 2 tests represent alternative methods as well as support different conclusions about moral judgment. The key difference is a stage-consistency (MJT) vs. a stage-preference (DIT) approach. Construct validity is defined in terms of 7 types of studies, and the approaches are compared. The stage-preference approach systematically outperforms the stage-consistency approach. Benchmarking by using classic studies in moral judgment illustrates an empirical, multistudy, quantitative approach to moral judgment research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relation of moral judgment development to formal education.

Tested Ss from an ongoing longitudinal study initiated by the present 1st author and colleagues (see record 1974-32073-001) at 2-yr intervals after high school graduation on the Defining Issues Test and other measures of moral thinking (e.g., socio-moral concepts test, political attitudes test) to investigate the relationship of moral-judgment development to formal education. In a 3rd testing 4 yrs after high school, 59 Ss participated; of these, 39 were in a 4th testing 6 yrs later. When Ss were divided into low- and high-education groups, depending on how many years of college they attended, the groups showed increasingly divergent developmental pathways. The high-education group showed increasing gains, and the low-education group showed a leveling off. Years in college added significantly to the predictability of moral judgment in young adulthood, above and beyond that accounted for by initial high school scores on the same moral-judgment measures. Results complement and extend findings from other cross-sectional and longitudinal studies on the relation of formal education to moral judgment. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Longitudinal study of the Defining Issues Test of moral judgment: A strategy for analyzing developmental change.

After 2 yrs, 88 adolescents (16-20 yrs) were retested on the author's Defining Issues Test of moral judgment, the Comprehension of Social-Moral Concepts Test, and the Law and Order Attitude Test. Significant developmental change was found on all 3 measures. Both younger and older Ss showed significant increases in principled moral thinking, but the younger group also showed preconventional to conventional shifts. There was no evidence for step-by-step movement, and sex differences were negligible. Among high school graduates, those going away to college gained twice as much as noncollege Ss. 2-yr stability on the Defining Issues Test was r(49) = .68 for the younger group and r(37) = .54 for those graduating from high school. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The mechanistic prediction of transient fission-gas release from LWR fuel

The steady-state and transient gas release and swelling subroutine (GRASS-SST) is a mechanistic computer code for the prediction of fission-gas behavior in UO₂-base fuels. GRASS-SST treats fission-gas release and fuel swelling on an equal basis and simultaneously treats all major mechanisms that influence fission-gas behavior. The GRASS-SST transient analysis has evolved through comparisons of code predictions with the fission-gas release and physical phenomena that occur during reactor operation and transient direct-electrical heating (DEH) testing of irradiated light-water reactor fuel. The GRASS-SST steady-state analysis has undergone verification for end-of-life fission-gas release and intragranular bubble-size distributions. The results of GRASS-SST predictions for transient fission-gas release during DEH tests are in good agreement with experimental data. Comparisons of GRASS-SST predictions of gas release and bubble-size distributions with the results of DEH transient tests indicate that (1) coalescing bubbles do not have sufficient time to grow to equilibrium size during most transient conditions, (2) mobilities of fission-gas bubbles in UO₂ are enhanced during nonequilibrium conditions if the excess pressure in the bubble is sufficient to generate an equivalent stress greater or equal to the yield stress of the surrounding matrix, and (3) channel formation on grain surfaces and coalescence of the channels with each other and with the tunnels of gas along the grain edges can contribute to grain-boundary separation and/or the rapid, long-range interconnection of porosity. The phenomena of grain-boundary separation and/or long-range interconnection of porosity provides an important release mechanism for fission gas that has moved out of the grains of irradiated fuel.