The Limitations of Equivalent Linear Site Response Analysis Considering Soil Nonlinearity Properties

Seismic site effect has been a major issue in the field of earthquake engineering due to the large local amplification of the seismic motion. This paper presents the importance of an appropriate soil behavior model to simulate earthquake site response and gives a critical overview of the field of site response analysis. Some of the well known site response analysis methods are summarized and discussed. The objective of this paper is to investigate the influences of nonlinearity on the site response analysis by means of a more precise numerical model. In this respect, site responses of four different types of one layered soil deposit, based on various shear wave velocities, with the assumption of linear and rigid base bedrock, were analyzed by using the equivalent linear and fully nonlinear approaches. Nonlinear analyses’ results were compared with those of the linear method and the similarities and differences are discussed. As a result, it is concluded that, in the case of nonlinearity of soil under strong ground motions, 1-D equivalent linear modeling overestimates the amplification patterns in terms of absolute amplification level, and cannot correctly account for resonant frequencies and hysteric soil behavior. Hence more practical and appropriate numerical techniques for ground response analysis should be surveyed

Reducing the clique and chromatic number via edge contractions and vertex deletions.

We consider the following problem: can a certain graph parameter of some given graph G be reduced by at least d, for some integer d, via at most k graph operations from some specified set S, for some given integer k? As graph parameters we take the chromatic number and the clique number. We let the set S consist of either an edge contraction or a vertex deletion. As all these problems are NP-complete for general graphs even if d is fixed, we restrict the input graph G to some special graph class. We continue a line of research that considers these problems for subclasses of perfect graphs, but our main results are full classifications, from a computational complexity point of view, for graph classes characterized by forbidding a single induced connected subgraph H

Diagnostic Performance of 64-Channel Multislice Computed Tomography in Assessment of Significant Coronary Artery Disease in Symptomatic Subjects

The recent development of 64-channel multislice computed tomography (MSCT) has resulted in noninvasive coronary artery imaging improvement. This study was conducted to determine the accuracy of 64-slice MSCT in a relatively unselected group of 143 patients with presentations suggestive of coronary artery disease, including those with unstable angina pectoris, who underwent both coronary computed tomographic angiography and invasive coronary angiography. No arrhythmia was considered an exclusion criterion except for atrial fibrillation or frequent extrasystoles. In patients with fast heart rates, a β blocker was administered orally. Data were obtained using electrocardiography gated 64-slice MSCT. Computed tomographic angiography and invasive coronary angiography findings of each coronary segment were compared to determine the sensitivity, specificity, positive predictive value, and negative predictive value of MSCT in the detection of their normalcy or insignificant (<50 diameter decrease) stenosis versus significant (�50 diameter decrease) stenosis or total occlusion. In per-patient assessment, the calculated sensitivity, specificity, positive predictive value, and negative predictive value of MSCT were 96, 67, 91, and 83, respectively. These values in per-artery evaluation were 94, 94, 87, and 97, and corresponding values in per-segment analysis were 92, 97, 77, and 99, respectively. In conclusion, computed tomographic angiography has high diagnostic performance in the assessment of significant coronary artery disease in most patients in a daily routine practice, including those presenting with unstable angina pectoris symptoms. © 2007 Elsevier Inc. All rights reserved

Elevated serum matrix metalloproteinase 9 (MMP-9) concentration predicts the presence of colorectal neoplasia in symptomatic patients

Early detection of polyps or colorectal carcinoma can reduce colorectal carcinoma-associated deaths. Previous studies have demonstrated raised serum levels of matrix metalloproteinase 9 (sMMP-9) in a range of cancers. The aim of this study was to investigate the role of sMMP-9 levels in identifying colorectal neoplasia. Consenting patients donated a blood sample and were assessed by proforma-led history and physical examination. Samples were analysed for sMMP-9 concentration (enzyme-linked immuno-sorbant assay) and compared to final diagnoses. Logistic regression modelling determined independent factors associated with neoplasia. A total of 365 patients were recruited of whom 300 were analysed, including 46 normal controls. A total of 27 significant adenomas and 63 malignancies were identified. The median sMMP-9 concentration was 443ng ml−1 (IQR: 219–782; mean: 546). Patients with neoplasia had significantly elevated sMMP-9 levels (P<0.001). Logistic regression modelling identified elevated log(sMMP-9) as the most significant predictor of neoplasia (χ2=38.33, P<0.001). Other significant factors were age, sex, smoking history, abdominal pain and weight loss. The model accurately predicted neoplasia in 77.3% of cases. Sensitivity and specificity were 77.9 and 77.1%. sMMP-9 estimation can accurately stratify patient to low- or high-risk cohorts. Serum sampling is a potential means of avoiding unnecessary colonoscopy and reducing patient anxiety, iatrogenic morbidity and mortality, and cost

Protection against live rotavirus challenge in mice induced by parenteral and mucosal delivery of VP6 subunit rotavirus vaccine

Live oral rotavirus (RV) vaccines are part of routine childhood immunization but are associated with adverse effects, particularly intussusception. We have developed a non-live combined RV – norovirus (NoV) vaccine candidate consisting of human RV inner-capsid rVP6 protein and NoV virus-like particles. To determine the effect of delivery route on induction of VP6-specific protective immunity, BALB/c mice were administered a vaccine containing RV rVP6 intramuscularly, intranasally or a combination of both, and challenged with murine RV. At least 65 % protection against RV shedding was observed regardless of delivery route. The levels of post-challenge serum VP6-specific IgA titers correlated with protection