Reliability and scale effect in toughness of concrete structures

In the present work, the distribution of the random toughness characteristics (i.e. critical energy release rate, G_1c) has been evaluated on the basis of experimental observations. Fracture test results from three groups of geometrically similar concrete specimens of size (width×total depth×thickness), 420×420×50–1680×1680×200 mm³, made with different maximum aggregate size of 9.5, 19, 38, and 76 mm were analyzed using a recently proposed distribution of extremes. In applications of probability, it is important to use an appropriate distribution type and adequate techniques for estimating the parameters of distribution. In this study, a new type distribution of minima is employed for probability computations. It was noticed that the entropy of distribution increases with the crack length, i.e. the uncertainty of toughness, G_1c, value increases with crack length. A non-linear reduction of the maximum allowable splitting force with the defect size, a, was noticed. For large specimens, the maximum allowable splitting load is more sensitive to the required reliability level than that for small specimens. Reliability increases with aggregate size when all other conditions were constant.     

Replacement of beef fat in Frankfurters by interesterified palm,cottonseed and olive oils

Three interesterified vegetable oils (IVOs) prepared from palm, cottonseed, and olive oil, respectively, have been studied for application to Frankfurters. Beef fat (10%) was replaced by one of the IVOs at 20, 60 or 100%. Fatty acid composition of the lipid fraction in the Frankfurters and saturated/unsaturated ratios were established for all batches. We found that total or partial replacement of beef fat by IVOs did not lead to significant changes in appearance, colour, texture, flavour or sensory score. We conclude that IVOs may be successfully applied as beef fat substitutes in Frankfurters.     

The measurement of gastric motor function and transit in man by echo planar magnetic resonance imaging

Echo-planar imaging (EPI) can be used to produce snapshot images of the human stomach and antro-pyloro-duodenal segment in real time as an alternative technique to intubation and exposure to ionizing radiation. The method has been further developed to monitor simultaneous gastric motility and gastric emptying of liquid and solid meals. The model has been utilized to study the effects of pharmacological agents on gastric function.Eight normal subjects were imaged in a 0.5-T superconducting magnet for up to 6 h following ingestion of 800 ml tap water, followed by 500 ml porridge test meal + 500 ml tap water. A rapid multislice technique was adopted to image adjacent transverse slices (10 mm thick) through the gastric region. In addition, three subjects were orally dosed with 20 mg of the prokinetic agent Cisapride. Gastric volumes for each slice were calculated and summed to produce a measure of total gastric volume and gastric emptying. Contractile activity at the level of the antro-pyloric segment was detected using sequential 128 ms images at 3 s intervals. Alternate measurements of gastric volume and motility were made for the duration of the study.Gastric emptyingT _1/2's (times to empty 50% of the gastric contents) of 12.9 min for water and 116 min for porridge were in agreement with results obtained by the traditional techniques of gamma scintigraphy and impedance imaging. The frequency of gastric contractions increased from 2.4 contractions per minute (cpm) to 3.2 cpm following water and from 2.9 to 3.2 cpm following porridge. The prokinetic effect of enhanced coordination of antroduodenal contractions was also observed. These studies have demonstrated that EPI can be used to detect and image gastroduodenal function in man, totally noninvasively, and can be used to study the effects of drugs acting on the gastrointestinal tract.     

Anti-virtual machines and emulations

Virtual Machines are important infrastructural tools for malware analysis. They provide safe yet accurate way of evaluating real life behavior and impact of any executable code, thus providing a better understanding of obfuscated or non conventional portions of code within a binary file. Many virtual machines, such as VMware, Qemu, VirtualBox and SandBoxes, are available and are widely adopted by malware researchers and analysts. Moreover, many antivirus scanners have their own implementation of emulators to achieve comparable results by running malicious code within a controlled environment in order to decrypt obfuscated code. Virus writers have always responded to these technologies. Most malware today uses anti-debug techniques to counter analysis and evade antivirus detection. Lately, malware like Zeus/SpyEye and associated families such as Smoaler, Dromedan, Kazy, Yakes, and other malware such as Spyrat or W32.Pilleuz, have deployed techniques to disrupt the use of virtual machines and emulators. These malware families are able to implement different variations of disruption techniques within single samples or within related groups of malware before propagation. This paper will present a study of these anti-emulation and anti-virtual machine techniques.     

Preparation of heavily dopedn-type Ge-Si thermoelectric alloys

Germanium-silicon alloys doped with phosphorus were prepared in vacuum by rapidly pouring the molten alloy into cooled copper moulds containing the phosphorus dopant. Without any further treatment, the ingots are milled into powder of grain size (L 5 µm) and hot pressed. It is shown that a high degree of homogenization of the alloy constituents can be obtained in the final compacts, thus eliminating the need for zone-levelled starting material. It is also shown that this work is in agreement with the plastic flow model of sintering known as the Mackenzie-Shuttleworth-McClelland model. Electrical measurements indicate that the dopant is effectively and uniformly incorporated into the alloy.     

Nafcillin release from poly(acrylic acid–co–methyl methacrylate) hydrogels

Summary Copolymeric poly(acrylic acid-co-methyl methacrylate) hydrogels for three different compositions: (90/10), (80/20) and (60/40), have been studied. Drug release has been examined as a function of the hydrogel composition by HPLC (High Pressure Liquid Cromatography). The release experiments were carried out at 37 °C. The fraction of available drug release was linear in t^1/2. The values of the diffusional coefficient (0.50<n<1.0) indicate that the nafcillin release mechanism from the hydrogels in study is non-Fickian. The diffusion coefficients for this drug release have been calculated. The molecular diffusion of nafcillin through hydrogels is controlled by the swelling.     

Improving class probability estimates for imbalanced data

Obtaining good probability estimates is imperative for many applications. The increased uncertainty and typically asymmetric costs surrounding rare events increase this need. Experts (and classification systems) often rely on probabilities to inform decisions. However, we demonstrate that class probability estimates obtained via supervised learning in imbalanced scenarios systematically underestimate the probabilities for minority class instances, despite ostensibly good overall calibration. To our knowledge, this problem has not previously been explored. We propose a new metric, the stratified Brier score, to capture class-specific calibration, analogous to the per-class metrics widely used to assess the discriminative performance of classifiers in imbalanced scenarios. We propose a simple, effective method to mitigate the bias of probability estimates for imbalanced data that bags estimators independently calibrated over balanced bootstrap samples. This approach drastically improves performance on the minority instances without greatly affecting overall calibration. We extend our previous work in this direction by providing ample additional empirical evidence for the utility of this strategy, using both support vector machines and boosted decision trees as base learners. Finally, we show that additional uncertainty can be exploited via a Bayesian approach by considering posterior distributions over bagged probability estimates.     

Cephazoline sodium release from poly(N‐isopropyl acrylamide‐co‐N,N‐dimethylacrylamide) hydrogels

Hydrogels are hydrophilic polymers that swell to an equilibrium volume in the presence of water, preserving their shape. The dynamic swelling behavior of poly(N‐isopropylacrylamide‐co‐N,N‐dimethylacrylamide) [poly(NIPA‐co‐DMA)] copolymers at 37°C was investigated. It was observed that the swelling degree in the copolymers decreases with the N‐isopropylacrylamide content. In addition, the liberation mechanism was found to be Fickian. Diffusion coefficients according to Fick′s law as a function of the N‐isopropylacrylamide concentration and results of the release process are reported. The kinetics of cephazoline sodium release from poly(NIPA‐co‐DMA) hydrogels with different compositions was studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3433–3437, 2004