Engineering computation under uncertainty - Capabilities of non-traditional models

This paper provides a review of various non-traditional uncertainty models for engineering computation and responds to the criticism of those models. This criticism imputes inappropriateness in representing uncertain quantities and an absence of numerically efficient algorithms to solve industry-sized problems. Non-traditional uncertainty models, however, run counter to this criticism by enabling the solution of problems that defy an appropriate treatment with traditional probabilistic computations due to non-frequentative characteristics, a lack of available information, or subjective influences. The usefulness of such models becomes evident in many cases within engineering practice. Examples include: numerical investigations in the early design stage, the consideration of exceptional environmental conditions and socio-economic changes, and the prediction of the behavior of novel materials based on limited test data. Non-traditional uncertainty models thus represent a beneficial supplement to the traditional probabilistic model and a sound basis for decision-making. In this paper non-probabilistic uncertainty modeling is discussed by means of interval modeling and fuzzy methods. Mixed, probabilistic/non-probabilistic uncertainty modeling is dealt with in the framework of imprecise probabilities possessing the selected components of evidence theory, interval probabilities, and fuzzy randomness. The capabilities of the approaches selected are addressed in view of realistic modeling and processing of uncertain quantities in engineering. Associated numerical methods for the processing of uncertainty through structural computations are elucidated and considered from a numerical efficiency perspective. The benefit of these particular developments is emphasized in conjunction with the meaning of the uncertain results and in view of engineering applications.     

p53 and K-ras status in duodenal adenomas in familial adenomatous polyposis

BACKGROUND: The genetic alterations in patients with familial adenomatous polyposis (FAP) and duodenal adenomas are poorly characterized when compared with data relating to colorectal tumorigenesis in the same patients. METHODS: Point mutation of the K-ras oncogene and point mutation and overexpression of the TP53 tumour suppressor gene were investigated in 32 duodenal polyps (seven without mucosal pathology, 23 with mildly dysplastic adenomas and two with moderately dysplastic adenomas) from 21 patients with FAP. RESULTS: K-ras mutation, TP53 mutation or positive p53 staining were not found in duodenal polyps without histological abnormality. Of 25 duodenal adenomas, K-ras mutation was found in three (two mildly dysplastic, one moderately dysplastic), 20 showed positive p53 immunostaining, and mutation of the TP53 gene was found in one moderately dysplastic adenoma. p53 protein overexpression in duodenal adenomas was significantly more frequent than mutation of either K-ras or TP53 (P < 0.01). CONCLUSION: p53 dysfunction is a hallmark of duodenal adenomas in patients with FAP. Overexpression may indicate DNA damage and thus an early step in tumorigenesis.     

Development of male contraceptive vaccine--a perspective

Anti-disialoganglioside (GD2) monoclonal antibodies (MAbs) have been used in vivo for immunolocalization and in phase I and II trials to target disseminated neuroblastoma, the most common extracranial solid tumor in children. However, the efficacy of these first-generation MAbs is likely to be improved by using engineered anti-GD2 antibodies. The generation of single-chain antibody fragments (scFv) could be very helpful as these molecules can be further modified to produce recombinant molecules with pre-defined properties such as immunotoxins, chimeric, or bispecific antibodies. Thus, a scFv directed against GD2 (scFv 7A4) was cloned, sequenced, and expressed. Its binding properties were characterized and compared to that of the parental MAb 7A4. Nucleotide sequence analysis of the scFv 7A4 indicated that its VH region belongs to the V region IIID subgroup and the V kappa to the V region II subgroup. The scFv 7A4 bound to GD2+ neuroblastoma cell lines but not to GD2- cell lines or to GD2- cells isolated from peripheral blood. ELISA and thin-layer chromatography (TLC) indicated that it retained the anti-GD2 specificity, and exhibited a slight cross-reaction with GD3 as the parental MAb. This scFv makes it possible to develop new useful reagents through genetic engineering for adjuvant tumor therapy.     

Psychological predictors of pain during dental hygiene treatment

This study examined the role of catastrophizing (i.e. a tendency to exaggerate the threat value of potentially painful situations) in predicting pain experience during dental hygiene treatment. Participants in the research were 100 patients undergoing scaling and/or root planing procedures at Dalhousie University's Dental Clinic. Following treatment, participants completed the Pain Catastrophizing Scale, a measure of emotional distress, a pain scale, and the Dental Anxiety Scale-Revised. Participants who scored above the median on the Pain Catastrophizing Scale were classified as catastrophizers, participants who scored below the median were classified as noncatastrophizers. Results showed that catastrophizers reported significantly more dental anxiety, emotional distress and pain than noncatastrophizers; and that distress reactions were more pronounced in men that in women. Discussion focuses on the importance of addressing psychological factors in dental hygiene practice, particularly as they relate to reactions to dental hygiene procedures, and avoidance of dental care.     

Long-term outcome in acute myocardial infarction patients admitted to hospitals with and without on-site cardiac catheterization facilities. MITI Investigators. Myocardial Infarction Triage and Intervention

BACKGROUND: Previous studies have documented the strong association between availability of on-site cardiac catheterization facilities and increased use of coronary angiography in patients with acute myocardial infarction (AMI). Although these studies have shown little influence of the availability of catheterization labs on hospital mortality, no long-term follow-up has been reported. METHODS AND RESULTS: From a cohort of 12,331 AMI patients admitted to 19 Seattle area hospitals, we compared long-term outcome in 7985 patients admitted to hospitals with and 4346 patients admitted to hospitals without on-site catheterization labs. During the index hospitalization, patients admitted to hospitals with on-site catheterization were more likely to undergo coronary angiography (67.1% versus 39.3%, P<.0001), coronary angioplasty (32.5% versus 13.2%, P<.0001), or coronary bypass surgery (12.5% versus 9.5%, P<.0001). At 3-year follow-up, patients admitted to hospitals with on-site catheterization labs were more likely to undergo postdischarge angiography (19.2% versus 15.2%, P=.0001) and coronary angioplasty (11.6% versus 8.2%, P<.0001). This was associated with approximately $2500.00 per patient in higher cumulative costs. Despite this higher rate of procedure use, there was no association between admission to a hospital with on-site catheterization facilities and lower long-term mortality (multivariate hazard ratio, 1.0; 95% CI, 0.93 to 1.1., the hazard being associated with admission to hospitals with on-site catheterization facilities). CONCLUSIONS: In an urban area with unconstrained patient transfer mechanisms and high overall cardiac procedure use rates, AMI patients admitted to hospitals without on-site catheterization facilities were managed with fewer procedures during hospitalization and follow-up. This more conservative treatment approach was not associated with any observed increase in long-term mortality.     

Cricket-based robots

This article describes the development of an autonomous hybrid microrobot that uses legs for propulsion and support of the rear half of the body and a pair of wheels for support of the front half. McKibben artificial muscles actuate the legs, and compressed air is generated by an onboard power plant. Control is also onboard in the form of a PIC microcontroller, from Microchip Technology Inc., that controls the actuators through four three-way valves that are each made up of a pair of microelectromechanical system devices. Its motion resembles that of a cricket.     

Limestone Neutralisation of Arsenic-Rich Effluent from a Gold Mine

Traditionally acid mine water is neutralised with lime. Limestone is a cheaper alternative for such applications. A case study showed that limestone can be used effectively to replace lime for the neutralization of arsenic rich acid water. The cost of limestone treatment is 45.8% less than that of lime. The acidity can be removed from 33.5 to 0.06 g/L (as CaCO₃). The study also showed no significant differences in the TCLP characteristics of the resultant sludge when water is treated with lime or with limestone. Sludge from the limestone treatment process can be disposed of on a non-hazardous landfill site. An erratum to this article can be found at     

Wedge splitting experiments on three-layered particleboard and consequences for cutting

Three layered particleboard is a widely used and important plate material used for construction and furniture production. This implies that material parameters such as strength and elasticity in bending are determined. However, usually little or nothing is known about the fracture properties. This paper has the goal to investigate the material fracture properties in the three layers and discuss the linear and non-linear fracture mechanical properties with regard to board production and its consequences for cutting. It could be shown that the fracture properties of the solid boards are dominated by the bigger chips in the core of the plate and the fracture properties of boards are best characterized by the specific fracture energy. The linear elastic- and the non-linear elastic fracture mechanics approach of the outer layers shows essentially similar results, represented by brittle fracture. For the prediction of the cutting performance, linear elastic fracture mechanics parameters are considered to be more appropriate because these parameters describe the limit of linear elastic behaviour and therefore the case of smallest deformation zone. High stress concentration at the tool tip and low permanent deformation in the bulk material give the best cutting quality.     

Effect of oval defects in GaAs on the reliability of SiNx metal–insulator–metal capacitors

In this paper, we will assess the reliability of extrinsic defects in SiN_x metal–insulator–metal (MIM) capacitors as part of a GaAs high voltage (HV) FET process. The epitaxial GaAs layers used for this process contain a density of oval defects. Since the SiN_x is deposited at low temperatures, the MIM capacitors are amorphous and will always contain a certain amount of extrinsic defects. It will be shown that the number of extrinsic defects depends on the presence of the oval defects in the epitaxial GaAs layers. The reliability assessment will be done using electric field breakdown (Ebd), time dependent dielectric breakdown (TDDB) measurements and visual inspection. It will be shown that this combination can lead to an estimate of the lifetime and screening of capacitors containing extrinsic defects.