193-nm lithography

The trend in microelectronics toward printing features 0.25 μm and below has motivated the development of lithography at the 193-nm wavelength of argon fluoride excimer lasers. This technology is in its early stages, but a picture is emerging of its strengths and limitations. The change in wavelength from 248 to 193 nm will require parallel progress in projection systems, optical materials, and photo-resist chemistries and processes. This paper reviews the current status of these various topics as they have been engineered under a multiyear program at MIT Lincoln Laboratory     

An efficient parallel implementation of the MSPAI preconditioner

We present an efficient implementation of the Modified SParse Approximate Inverse (MSPAI) preconditioner. MSPAI generalizes the class of preconditioners based on Frobenius norm minimizations, the class of modified preconditioners such as MILU, as well as interface probing techniques in domain decomposition: it adds probing constraints to the basic SPAI formulation, and one can thus optimize the preconditioner relative to certain subspaces. We demonstrate MSPAI’s qualities for iterative regularization problems arising from image deblurring.Such applications demand for a fast and parallel preconditioner realization. We present such an implementation introducing two new optimization techniques: First, we avoid redundant calculations using a dictionary. Second, our implementation reduces the runtime spent on the most demanding numerical parts as the code switches to sparse QR decomposition methods wherever profitable. The optimized code runs in parallel with a dynamic load balancing.     

Fluoride content and mineralization of red deer (Cervus elaphus) antlers and pedicles from fluoride polluted and uncontaminated regions

In the present study, the expression and prognostic role of the CD44 splicing variants v5 and v6 were immunohistochemically investigated in 418 curatively resected gastric carcinomas. CD44v5 was expressed in 65.3 per cent (n = 273) and CD44v6 in 77.0 per cent (n = 322) of the tumours. Whereas the expression of CD44v5 was correlated with advanced pT categories, with lymph node involvement, and with the presence of blood and lymphatic vessel invasion, such a correlation could not be found for the variant v6. As shown by univariate analysis, patients with CD44v5-positive tumours had a significantly shorter overall survival than patients with CD44v5-negative tumours (P = 0.049). In contrast, expression of CD44v6 had no impact on prognosis (P = 0.574). In a multivariate analysis including the prognostic parameters pT category and pN category, as well as blood and lymphatic vessel invasion, the prognostic impact of CD44v5 expression could not, however, be maintained. Although in the present study the expression of CD44v5 was correlated with a more aggressive tumour type, these data suggest that neither CD44v5 nor CD44v6 can predict survival in patients with gastric cancer, nor is their expression a suitable tool for identifying subgroups of patients who may be at higher risk.     

Optimization of high-voltage self-blast interrupters by gas flow and electric field computations

Self-blast interrupters have the advantage of operating with low mechanical energy as they build up the pressure of the arc extinguishing gas flow from the thermal energy of the arc. This creates a higher pressure, but also a higher gas temperature than in interrupters with mechanical compression. Detailed flow field and electric field computations are necessary to achieve under such conditions the energy removal and dielectric recovery in view of an increase in breaking capacity and voltage rating. In particular, the optimization of the electric field/gas density distribution E//spl rho/ is a tool to improve the short-circuit and capacitive current breaking performance.     

Application of the fracture mechanics safety analysis to structural steel sections

This contribution presents a fracture mechanics safety analysis with finite element models applied on I-beams with defects in the tension flange. The moment rotation at room temperature was observed in the light of the toughness behaviour in front of initial notches. The results show very early crack initiation due to very large initial defects. The experiments were accompanied by a fracture mechanics safety analysis employing FEM. However, in temperature ranges of buildings plastically designed beams are subjected to sufficient rotation capacity, i.e. rotational ductility could be found.     

Monitoring regional fluoride pollution in the Saxonian Ore mountains (Germany) using the biomarker dental fluorosis in roe deer (Capreolus capreolus L.).

The spatial variation of fluoride contamination in the Saxonion part of the Ore mountains (Federal state of Saxony, Germany) was assessed by analysing the prevalence and severity of dental fluorosis in wild male roe deer aged 2 years or more (n = 794) from this region. The study area is exposed to increased atmospheric deposition of fluorides, originating from emission sources in the North-Bohemian brown coal belt. The severity of dental fluorosis in the permanent premolars and molars of one hemimandible per animal was assessed based on a scoring system and a dental lesion index of fluorosis (DLI) assigned to each specimen. On the basis of the mean DLI calculated for the roe deer originating from a certain municipal district, the respective deer sample was assigned to one of seven fluorosis categories, and a map showing the distribution of these categories was produced. Highest fluorosis categories were recorded for roe deer samples from the central and eastern parts of the study area that directly bordered on, or were located near to, the Czech-German border. A close spatial relationship between the main fluoride emission sources in North-Bohemia and the regions with the highest prevalence and severity of dental fluorosis in roe deer was discernible. The observed regional variation of fluoride pollution is in accordance with the results of other studies directly measuring fluoride deposition into the study area or fluoride levels in vegetation. A main advantage of the method used in this study over other ways of recording fluoride contamination of wildlife habitats is that it uses an established and continuously operated system of specimen collection, thereby enabling efficient monitoring with high spatial and temporal resolution at very low cost. Moreover, a clearly recognisable and relevant biological effect is measured which occurs in a dose-dependent manner over a range of environmentally relevant concentrations.