Introduction

The Journal of Supercomputing -     

Well-differentiated liposarcoma of the hypopharynx

We report a case of subacute bowel obstruction due to a compression of the rectosigmoid junction by a chronically distended bladder, occurring in a 91-year-old male suffering from a long-standing diabetes mellitus and a prostatic adenoma. Radiographic, water-soluble contrast enema and pelvic CT features are reported.     

Age-related changes in sympathetic modulation of sensory nerve activity in rat skin

OBJECTIVES: Sensory nerves play an important role in mediating neurogenic inflammation and subsequent tissue healing. A decrease in sensory nerve function with increasing age has been reported to correlate with poor tissue healing. Sympathetic nerves are known to modulate sensory nerve function, and changes in this modulation could also have important implications with ageing. The aims of this study were to examine the effect of different frequency electrical stimulation (ES) on the microvascular responses obtained to sensory nerve activation in young, aged and capsaicin-pretreated rats and modulation of these responses by sympathetic efferents. METHODS: Using laser Doppler flowmetry, vascular responses to antidromic ES of the sciatic nerve were monitored in the base of vacuum-induced blisters in the hind footpad. The non-selective alpha-adrenoceptor antagonist phentolamine (3 mg/kg, i.v.) was administered 20 min prior to ES. RESULTS: At high frequency ES (20V, 2ms, 15Hz for 1 min), the vascular response in old rats was significantly reduced (46 percent decrease, p < 0.05) compared to young control. At low frequency ES (20 V, 2 ms, 5 Hz for 1 min) however, older rats produced similar vascular responses to the young. Capsaicin-pretreated rats showed significantly reduced vascular responses to both high and low frequency ES, regardless of age. Pretreatment with phentolamine significantly increased the microvascular response in young rats at high (87 percent) and low (36 percent) frequency ES. In contrast, phentolamine significantly increased the ES-induced response in old rats at high frequency only (147 percent increase). CONCLUSIONS: The results suggest that the aged sensory nerve responds preferentially to low frequency ES and that sympathetic efferents exert an inhibitory modulatory effect on the vascular response evoked by sensory nerve stimulation. There are age-related changes in sympathetic modulation of sensory nerve-mediated responses which is dependent on stimulation frequency.     

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.     

The Valve Metal Character of Zirconium as inferred from anode potential measurements in mineral acid solutions

A study on the value metal character of Zr in 0.1 M solutions of H₂SO₄, HNO₃, and H₃PO₄ has been performed using the anode potential as the primary variable in galvanostatic, potentiostatic, and capacity measurements. A method of surface pre-treatment, which suppresses both O₂ evolution and metal dissolution, has been described. Kinetic parameters of oxide growth have been calculated. The results indicate that:

• (i) the high field approximation is applicable following an exponential law, and
• (ii) the height and activation distance of the energy barrier for ion transport through the oxide phase (Verwey model) are the same three acids.

Measurements have been also made on the dielectric breakdown of oxide, and this occurs at potentials above 200 V. Direct capacity measurements give similar results as those based on reciprocal capacity calculated from galvanostatic experiments. It is concluded that the dominant anodic oxide species is ZrO₂ having a dielectric constant of 25. Open circuit potential measurements show that Zr is spontaneously oxidized in the three acids.     

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.     

Thermoelectric properties of fine grained (75% Sb2Te3-25% Bi2Te3)p-type and (90% Bi2Te3-5% Sb2Te3-5% Sb2Se3)n-type alloys

The thermoelectric properties of fine-grained alloys prepared by either cold pressing and sintering or hot pressing in the range 5–50 m are compared with single-crystal best-direction values. It is shown that for thep-type alloy, almost the entire thermoelectric properties are recovered, i.e. the figure of merit for the finest grain size is almost the same as the best single-crystal value. The same trend is observed in then-type alloy except that 90% of the single-crystal figure of merit is recovered. These results are discussed in terms of a model which suggests that degradation of favourable thermoelectric properties by powdering the alloys is compensated by (1) decrease of thermal conductivity due to scattering of phonons at grain boundaries for grain sizes that are comparable to the mean free path of phonons; and (2) retention of some of the anisotropic properties of the single crystal in the fine-grained compacts.     

Application of a hybrid finite element method to determine stress intensity factors in unidirectional composites

In this paper a hybrid finite element method is applied in evaluation of the stress intensity factors K _I and K _II of unidirectional fiber reinforced composites. In order to satisfy the stress singularity at the crack tip a singular super-element based on a modified complementary energy principle is developed. The stress and displacement fields in the super-element are expressed in terms of polynomials of two complex variables ₁ and ₂ in the transformed -plane. The stiffness matrix of the super-element was determined by using a line integral along the boundary of the super-element. The displacement vector was expressed in terms of the element nodal displacement vector {q} and a properly selected shape function defined along the element boundary.Numerical results for K _I and K _II of glass-epoxy and graphite-epoxy unidirectional composites with cracks along the diameter of a circular cut out as well as elliptical cut outs were evaluated

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Résumé On applique, dans la présente étude, une méthode d'éléments finis hybrides à l'évaluation des facteurs d'intensité de contrainte K_I et K_II pour des composites renforcés de fibres unidirectionnelles. Pour tenir compte de la singularité de la contrainte à l'extrémité de la fissure, on développe un super élément singulier en se basant sur un principe modifié d'énergie complémentaire. Les champs de contraintes et de déplacements dans le super-élément sont exprimés sous forme polynormale de deux variables complexes ₁, et ₂ dans le plan de la transformée. La matrice de rigidité du super élément est, quant à elle, définie en utilisant une intégrale linéaire le long du contour de l'élément. Le vecteur de déplacement est exprimé par un vecteur (9) de déplacement nodal de l'élément, et par une fonction de forme appropriée, définie le long du contour de l'élément.On évalue les résultats numériques pour K_I et K_II, correspondant à des composites à fibres unidirection-nelles de types verre-epoxy et graphite-epoxy, oú des fissures se situeraient sur le diamètre de découpes circulaires et elliptiques