Securing Wireless Mesh Networks

Now found in domestic, commercial, industrial, military, and healthcare applications, wireless networks are becoming ubiquitous. Wireless mesh networks (WMNs) combine the robustness and performance of conventional infrastructure networks with the large service area and self-organizing and self-healing properties of mobile ad hoc networks. In this article, the authors consider the problem of ensuring security in WMNs, introduce the IEEE 802.11s draft standard, and discuss the open security threats faced at the network and data-link layers.     

Defining the outcome of immunosuppression withdrawal after liver transplantation

Successful immunosuppression withdrawal should benefit the natural history of organ transplantation patients. To identify the clinical hazards of removing drug treatment and possible characteristics that predict a favorable outcome in long-term liver recipients, immunosuppression was withdrawn completely and the clinicopathological outcome documented in 18 liver recipients. Indication for transplantation, HLA matching, early rejection history, and presence of microchimerism were examined as predictors of outcome. Chimerism was determined by polymerase chain reaction-based examination for donor-specific HLA-DRB1 alleles and Y-gene-specific nucleotide sequences. At 3 years, 5 patients (28%) remained completely off immunosuppression; 12 patients (67%) experienced histological graft changes: acute rejection in 4, portal tract inflammation/hepatitis in 7, and necrosis in 1. Hepatitis B or C viral infections did not account for the nonrejection patterns. Unmasking of systemic disorders occurred. Chimerism, demonstrated in 7 patients (39%), with skin the optimal tissue, was not associated with tolerance. Parameters associated with successful drug withdrawal were transplantation for non-immune-mediated liver disorders, fewer donor-recipient HLA A, B, and DR mismatches, and a low incidence of early rejection. Immunosuppression withdrawal is a feasible option in a proportion of selected liver recipients, but identification of tolerant patients remains imprecise.     

Pathologic fracture of the femur neck as first manifestation of a minute columnar cell carcinoma of the thyroid gland

This case report concerns a 64 year-old woman who presented a pathologic fracture of the femur neck. Histologic examination of the performed bone biopsy disclosed the presence of a carcinomatous metastasis with unusual microscopic features. The site of the primary tumor could be unequivocally determined as being the thyroid gland, as immunostaining of the tumor cells showed positivity with anti-thyroglobulin. The thyroidectomy specimen weighed 149 g, was nodular and partially calcified. Exhaustive microscopic examination finally revealed the presence of a minute columnar cell carcinoma, 0.6 cm in diameter, with obvious vascular invasion. This case illustrates well 1) the usefulness of immunostaining with anti-thyroglobulin in cases of bone metastasis with unusual microscopic features and unknown primary, as well as 2) the aggressiveness of this rare type of carcinoma of the thyroid.     

Focal nodular hyperplasia of the liver: a rational approach to treatment

Focal nodular hyperplasia of the liver in a 3 year old child has been successfully treated by ligation of the hepatic artery branches supplying the lesion. The prominence of the abnormal vasculature in the lesion and its possible aetiological involvement is stressed. Because of the risks of partial hepatectomy, hepatic artery ligation is suggested as the treatment of choice for focal nodular hyperplasia.     

Oral Dosage Development of a Human Rhinovirus and Non-Polio Enterovirus Inhibitor

WIN 63843, a Picornavirus replication inhibitor, is physically and chemically stable in the solid state, to light, elevated temperature, and humidity. This 3-ary15-trifluoromethyl disubstituted 1,2,4-oxadiazole compound has very low water solubility but is highly soluble in ethanol and in safflower seed and corn oils. Solubility in the vegetable oils is doubled by the synergistic effect of ethanol at the 16% alcohol concentration. Vegetuble oil solutions of WIN 63843 are thermally stable but react slowly in the presence of light resulting in an amidoxime compound (WIN 65489) formed by opening of the 1,2,4-oxadiazole ring. This reaction does not occur in oil solutions containing small concentrations of ethanol. Of biophannaceutical interest, the addition of ethanol or PEG-400 solutions of WIN 63843 to human gastric fluid resulted in oily droplet formation whereas crystals form upon addition of these solutions to water. Also, the compound is greater than 8,000 times more soluble in human gastric fluid.     

Analog CMOS integrated circuit design: research and undergraduateteaching

The authors describe the use of software that was developed as part of a research program in analog CMOS integrated circuit design for an undergraduate course on analog VLSI design. The software includes some unusual uses of readily available, inexpensive, and easy-to-use programs available for microcomputers such as Macintosh or IBM-PC clones. Although initially intended to help with the design of CMOS operational amplifiers, the IC design method used is very general; other possible applications are described. The flexibility of these programs also allows them to be used with other CAD (computer-aided design) software, including circuit simulators and programs for schematic entry and layout. The software tools allow undergraduate students to complete analog CMOS integrated circuit designs using advanced CAD techniques but without being overwhelmed or losing touch with the underlying circuit design principles. Details of the programs and their use are presented together with the resulting analog IC designs fabricated using MOSIS (MOS Implementation Service)     

Kinetic and Stability Study of an Investigative Antirhinovirus Compound

A hydrolytic acid and base catalyzed ring opening reaction has been demonstrated for a 1,2,4-oxadiazole antiviral compound (WIN 63843) resulting mainly in an amidoxime product. Decomposition products and related impurities were detected using a gradient HPLC method. The hydrolysis reaction was first-order for 35% ethanol/buffer solutions in a 50°C chamber or a light cabinet (1000 ft-candles), the greatest stability being between pH 4 and 6. Furthermore, increasing ethanol concentrations resulted in a great decrease in reaction rates. Therefore, for oral or aerosol solution formulations, light protection, pH control between 4 and 6 and the highest permissible ethanol concentrations would be advantageous. This study has shown that the highly electronegative trifluoromethyl group at the 5 position increases the lability of a 1,2,3-oxdiazole compound.     

Directed Biosynthesis of Phytotoxic Alkaloids in the Cyanobacterium Nostoc 78–12A

Out of the green! Precursor‐directed biosynthesis allowed for the production of new nostocarboline derivatives that display phytotoxic and algicidal properties—in a phototrophic organism. The mechanism of action includes downregulation of photosynthesis, as demonstrated by chlorophyll‐a fluorescence imaging.

     

MAC-layer rate control for 802.11 networks: a survey

Rate control at the MAC-layer is one of the fundamental building blocks in many wireless networks. Over the past two decades, around thirty mechanisms have been proposed in the literature. Among them, there are mechanisms that make rate selection decisions based on sophisticated measurements of wireless link quality, and others that are based on straight-forward heuristics. Minstrel, for example, is an elegant mechanism that has been adopted by hundreds of millions of computers, yet, not much was known about its performance until recently. The purpose of this paper is to provide a comprehensive survey and analysis of the existing solutions from the two fundamental aspects of rate control—metrics and algorithms. We also review how these solutions were evaluated and compared against each other. Based on our detailed studies and observations, we share important insights on future development of rate control mechanisms at the MAC-layer. This discussion also takes into account the recent developments in wireless technologies and emerging applications, such as Internet-of-Things, and shows issues that need to be addressed in the design of new rate control mechanisms suitable for these technologies and applications.