A methodology aimed at better integration of functional verification and RTL design

The advent of new 65 nm/90 nm VLSI technology and SoC design methodologies has brought an explosive growth in the complexity of modern electronic circuits. As a result, functional verification has become the major bottleneck in any digital design flow. Thus, new methods for easier, faster and more reusable verification are required. This paper proposes a verification methodology (VeriSC2) that guides the implementation of working testbenches during hierarchical decomposition and refinement of the design, even before the RTL implementation starts. This approach uses the SystemC Verification Library (SCV), in a tool capable of automatically generating testbench templates. A case study from a MPEG-4 decoder design is used to show the effectiveness of this approach.     

CRACK PROPAGATION STUDIES ON Al 7475 ON THE BASIS OF CONSTANT AMPLITUDE AND SELECTIVE VARIABLE AMPLITUDE LOADING HISTORIES

Abstract— Fatigue crack propagation behaviour under variable amplitude loading is significantly influenced by load history induced sequence effects. Because the understanding of the causes of such sequence effects is still rather limited, crack propagation predictions become difficult. In the present investigation an exploratory test program with simple variable amplitude load sequences was performed, which was designed to improve the general understanding of sequence effects and to offer a basis both for an evaluation of existing crack propagation prediction models and for the development of improved methods.
The investigations were performed on center cracked 8 mm thick Al 7475-T7351 specimens. In the first part of the study constant amplitude tests were performed over a wide range of R-ratios. The test results and the transition of the fracture mode during tests could be represented on the basis of the effective Δ K -value.
In the second part of the paper tests with simple systematically varied sequences of high loads, low loads and underloads were performed and the crack propagation behaviour was measured. In order to obtain detailed information on the crack propagation increments per cycle, fractographic analyses were also performed. It was found that also under variable amplitude loading the crack propagation approximately followed the effective Δ K -values, except in one case.
A linear (non-interaction) prediction model could not describe the observed crack propagation behaviour. The results of the application of a model assuming a constant crack opening level are also given. Finally, some general viewpoints regarding further developments of models are outlined.     

PH-sensing 96-well microtitre plates for the characterization of acid production by dairy starter cultures

A new method for characterization of acid production by dairy starter cultures is presented. Microplates with integrated optical pH sensors are developed. Two fluorophores, a pH-sensitive and a pH-insensitive one are immobilised at the bottom of a polystyrene 96-well microtitre plate. The pH-insensitive fluorophore serves as an internal reference and makes calibration unnecessary. The sensor measures pH accurately in optically well-defined media. Particles and fluorophores contained in the bulk medium disturbed the measurements. Despite these disturbances it was possible to clearly sense differences in inoculum type and in inoculum sizes of cultures of Lactococcus lactis and of Streptococcus thermophilus at 30 and 37 degrees C. Besides a pH-related signal there is information about other changes during milk fermentation. The cultivation results were compared with those from the established CINAC-method. From this comparison it can be concluded that the new method can be used reliably to characterize particularly a large number of strains for screening purposes but also for quality control.     

DNA mismatch-specific base flipping by a bisacridine macrocycle

Most, if not all, enzymes that chemically modify nucleobases in DNA flip their target base from the inside of the double helix into an extrahelical position. This energetically unfavorable conformation is partly stabilized by specific binding of the apparent abasic site being formed. Thus, DNA base-flipping enzymes, like DNA methyltransferases and DNA glycosylases, generally bind very strongly to DNA containing abasic sites or abasic-site analogues. The macrocyclic bisacridine BisA has previously been shown to bind abasic sites. Herein we demonstrate that it is able to specifically recognize DNA base mismatches and most likely induces base flipping. Specific binding of BisA to DNA mismatches was studied by thermal denaturation experiments by using short duplex oligodeoxynucleotides containing central TT, TC, or TG mismatches or a TA match. In the presence of the macrocycle a strong increase in the melting temperature of up to 7.1 degrees C was observed for the mismatch-containing duplexes, whereas the melting temperature of the fully matched duplex was unaffected. Furthermore, BisA binding induced an enhanced reactivity of the mispaired thymine residue in the DNA toward potassium permanganate oxidation. A comparable reactivity has previously been observed for a TT target base mismatch in the presence of DNA methyltransferase M.TaqI. This similarity to a known base-flipping enzyme suggests that insertion of BisA into the DNA helix displaces the mispaired thymine residue into an extrahelical position, where it should be more prone to chemical oxidation. Thus, DNA base flipping does not appear to be limited to DNA-modifying enzymes but it is likely to also be induced by a small synthetic molecule binding to a thermodynamically weakened site in DNA.     

Continuous spinal analgesia. Comparison between patient-controlled and bolus administration of plain bupivacaine for postoperative pain relief

The purpose of this study was to examine the changing trends in surgical management of patients with abdominal aortic aneurysms at a tertiary care teaching hospital over the past 40 years, by analysis of demographic data, perioperative variables and outcomes on all patients having abdominal aortic aneurysm surgery between 1955 and 1993. Some 1604 abdominal aortic aneurysms were assessed. The annual rate of abdominal aortic aneurysm surgery increased from 17.6 to 67.8 cases per year. The non-ruptured to ruptured abdominal aortic aneurysm ratio increased from 2.4:1 in the first decade to 3.4:1 in the last 5 years. In non-ruptured abdominal aortic aneurysm repairs, the following variables changed over the four decades: patients age over 80 years increased (2.4% to 8.0%; P<0.04), concomitant lower-limb occlusive disease increased (12.2% to 23.7%; P<0.02), prevalence of smaller aneurysms (4-6 cm) increased (16.0% to 54.2%; P<0.0001); intraoperative hypotension decreased (9.0% to 0.7%; P<0.0001), postoperative hemorrhage decreased (8.2% to 0.0%, P<0.0001), postoperative leg ischemia decreased (5.7% to 1.1%; P<0.02) and postoperative amputation rate decreased (3.2% to 0.0%; P<0.03). There was a significant decrease in perioperative mortality (17.0% to 3.4%; P<0.0001). For ruptured aneurysms, early operation (within 1 h of admission) increased from 8.7% to 55.8% (P<0.0001), prevalence of intraoperative hypotension decreased (50.0% to 23.5%; P<0.001), and major venous injury decreased (18.0% to 5.2%; P<0.05). Mortality, however, did not decrease significantly (54.2% to 44.2%; P=0.32). In conclusion, there was a significant decrease in mortality and morbidity associated with non-ruptured abdominal aortic aneurysm repair over the four decades studied. In addition, older patients with smaller aneurysms and more co-morbid conditions were operated on during this period. Mortality for patients operated on for ruptured abdominal aortic aneurysm repair has not changed significantly.     

Age-related thickening of basement membrane in stria vascularis capillaries

Several studies have examined the activity of neurons in hypothalamic tissue slices. The present experiments studied relationships between neuronal activity (firing rate and thermosensitivity) and tissue survival as a function of time and slice thickness. Rat hypothalamic tissue slices were sectioned at different thicknesses (350, 450, and 600 microm) and maintained in an oxygenated interface chamber which was perfused with artificial cerebrospinal fluid (ACSF). Electron and light microscopy were used to examine tissue morphology at different depths from the slice surfaces, and extracellular recordings were used to measure each cell's spontaneous activity and response to changes in temperature. Tissue damage was most evident at tissue layers nearest the gas-exposed surface. At 9 h in the chamber, 350 microm thick slices showed subtle changes in morphology with little difference between the gas-exposed and ACSF-exposed surfaces. In the 450 and 600 microm thick slices, tissue degeneration became more evident with increased damage at the gas-exposed surface. This damage extended fully into the tissue of the 600 microm section. There were no differences in firing rate or thermosensitivity between 350 and 450 microm slices; but in 600 microm slices, there were fewer spontaneously active neurons, although these neurons had a higher mean thermosensitivity. Based on the incidence of spontaneous activity and morphological integrity, the results suggest that electrophysiological experiments using 350 microm slices are preferable to experiments using thicker slices.     

Plasminogen activator inhibitor-1 4G/5G-polymorphism and factor V Q506 mutation are not associated with myocardial infarction in young men

OBJECTIVE: To evaluate the differences in clinical symptoms and radiological findings between smear-positive non-tuberculous mycobacteria (NTM) and smear-negative, culture-positive NTM. Also, to evaluate the differences in clinical symptoms and radiological findings between Mycobacterium avium and M. intracellulare. DESIGN: A retrospective study was performed of 200 cases with positive pulmonary cultures for NTM between January 1989 and December 1996. It was determined whether or not pulmonary disease was caused by NTM using the 1990 criteria recommended by the American Thoracic Society. Clinical symptoms and radiological findings were compared between groups. RESULTS: Fever and hemoptysis were more frequently observed in smear-positive patients (26/50, 52%, and 24/50, 48%, respectively) than in smear-negative, culture-positive patients (8/38, 21.1%, P < 0.005, 8/38, 21.1%, P < 0.01, respectively). In addition, cavity formation was more frequently observed in chest computed tomography scans of smear-positive patients (19/36, 52.8%) than in smear-negative patients (6/31, 19.4%, P < 0.005). Finally, cavity formation tended to be more frequently observed with M. avium than with M. intracellulare. CONCLUSION: The present study demonstrates differences in clinical symptoms and radiological findings between smear-positive and smear-negative NTM cases, as well as between M. avium and M. intracellulare.