Analysis and simulation of substrate coupling in integrated circuits

A technique is presented which allows efficient calculation of substrate-coupling macromodels in integrated circuits. the technique can be used to calculate node-to-node resistances or impedances in substrate models. Examples of the technique applied to several test structures are presented.     

Direct monitoring of the calcium concentration in the sarcoplasmic and endoplasmic reticulum of skeletal muscle myotubes

Direct monitoring of the free Ca2+ concentration in the sarcoplasmic reticulum (SR) was carried out in rat skeletal myotubes transfected with a specifically targeted aequorin chimera (srAEQ). Myotubes were also transfected with a chimeric aequorin (erAEQ) that we have demonstrated previously is retained in the endoplasmic reticulum (ER). Immunolocalization analysis showed that although both recombinant proteins are distributed in an endomembrane network identifiable with immature SR, the erAEQ protein was retained also in the perinuclear membrane. The difficulty of measuring [Ca2+] in 100-1000 microM range was overcome with the use of the synthetic coelenterazine analogue, coelenterazine n. We demonstrate that the steady state levels of [Ca2+] measured with srAEQ is around 300 microM, whereas that measured with erAEQ is significantly lower, i.e. around 200 microM. The effects of caffeine, high KCl, and nicotinic receptor stimulation, in the presence or absence of external calcium or after blockade of the Ca-ATPase, were investigated with both chimeras. The kinetics of [Ca2+] changes revealed by the erAEQ were similar, but not identical, neither quantitatively nor qualitatively, to those monitored with the srAEQ, indicating that at this stage of muscle development, differences exist between SR and ER in their mechanisms of Ca2+ handling. The functional implications of these findings are discussed.     

Vascular aging. Role of elastin receptor

A distinction is made between atheromatous plaque formation and arteriosclerosis, only this second process is strictly age-dependent. Interactions between lipids and constituents of the vascular wall are however involved in both processes, although by different mechanisms. The progressive increase with age of elastase activity is a second important factor in the age-dependent progression of arteriosclerosis. The fragmentation of elastic fibers produces elastin peptides, present in the circulating blood in microgram/ml conc-s, increasing in several arteriopathies. The constant presence of elastin peptides in the circulation maintains activated the elastin receptor (16) on endothelial cells producing NO* with vasorelaxing activity (18). The simultaneous production of superoxyde leads to the formation of peroxynitrate, neutralized by reduced glutathion. This process, maintained over decades may well impair the antiradical defense mechanisms of the cells and deprive the endothelium from the vasorelaxing activity of NO*. We propose therefore that the maintained activation of the elastin receptor with free radical and lytic enzyme production might well represent the initiating process underlying atherogenesis.     

A superconducting X-ray spectrometer with a tantalum absorber andlateral trapping

We report the development of Nb-Ta-Al-Al₂O₃-Al superconducting tunnel junction structures for high energy resolution and high efficiency X-ray detection. These devices utilize a Ta X-ray absorber with superconductor “bandgap engineered” quasiparticle trapping to improve charge collection. Experimental results at 0.3 K are presented, showing energy resolution of 102 eV full-width-half-maximum for 6 keV X-rays. Collected charge is in excess of 5×10⁶ electrons. The absorption efficiency is better than 35%. Devices thermally cycle with no change in characteristics     

Behavior of cylindrical tanks whose axes are horizontal

A cylindrical tank is mounted with its axis horizontal. Supports on either side run lengthwise. If the tank wall is thin, deformations significantly affect the stresses, so that standard stress formulae (which ignore deformations) may over-estimate stresses by a factor of ten or more. In this paper, deformations are accounted for by a nonlinear analysis. Stresses and deformed shapes are reported for various positions of the supports, radius to thickness ratios, and depths of fill.     

Performance-Analyse und -Optimierung in der Softwareentwicklung

Nicht-funktionale Anforderungen an ein Softwaresystem beschreiben Aspekte, die nicht direkt die Funktionalit?t, wie sie der Benutzer sieht, betreffen.     

The Year 2015 Fusion Power Conversations

Assuming significant technical success in the ITER project by the year 2015, it is likely that governments will want to develop a more comprehensive plan for DT tokamak fusion power commercialization. To provide a glimpse into many of the related issues, we construct conversations between the director of the U.S. fusion program and three specialists key to commercial fusion success: an environment and safety regulator, an environmentalist, and an electric generation investor. The insights from these imagined conversations will hopefully be of value as tokamak fusion power proponents plan beyond ITER.