A conformance test suite for TTCN-3 tools

With more than 10 years of maturing through industrial use and standardization, the Testing and Test Control Notation (TTCN-3) has become a widely used technology that many businesses depend upon for ensuring their product quality. With the rising number of supporters and tools, the demand for a means to assess the standards compliance of TTCN-3 tools has increased. In this article, we describe the motivation, approach, methodology, and results of the still ongoing project to develop a standardized conformance test suite for TTCN-3 tools. We discuss the challenges involved in creating such a test suite, the way to deal with imposed resource limitations of the project, and where we think the effort is heading.     

On detecting co-resident cloud instances using network flow watermarking techniques

Virtualization is the cornerstone of the developing third-party compute industry, allowing cloud providers to instantiate multiple virtual machines (VMs) on a single set of physical resources. Customers utilize cloud resources alongside unknown and untrusted parties, creating the co-resident threat—unless perfect isolation is provided by the virtual hypervisor, there exists the possibility for unauthorized access to sensitive customer information through the exploitation of covert side channels. This paper presents co-resident watermarking, a traffic analysis attack that allows a malicious co-resident VM to inject a watermark signature into the network flow of a target instance. This watermark can be used to exfiltrate and broadcast co-residency data from the physical machine, compromising isolation without reliance on internal side channels. As a result, our approach is difficult to defend against without costly underutilization of the physical machine. We evaluate co-resident watermarkingunder a large variety of conditions, system loads and hardware configurations, from a local laboratory environment to production cloud environments (Futuregrid and the University of Oregon’s ACISS). We demonstrate the ability to initiate a covert channel of 4 bits per second, and we can confirm co-residency with a target VM instance in $<$ 10 s. We also show that passive load measurement of the target and subsequent behavior profiling is possible with this attack. We go on to consider the detectability of co-resident watermarking, extending our scheme to create a subtler watermarking attack by imitating legitimate cloud customer behavior. Our investigation demonstrates the need for the careful design of hardware to be used in the cloud.     

Vapor-liquid equilibria in the argon-methane system

Vapor-liquid equilibrium compositions have been measured for the argon-methane system at 115.2°, 123.4° and 137.1°K, by means of a forced-recirculation apparatus. A modified Redlich-Kwong equation of state with the incorporation of a binary interaction constant has been successfully employed to represent the data. Liquid activity coefficients have been evaluated and correlated.     

Empirical equations for the thermodynamic properties of aqueous sodium chloride

Equations for the thermodynamic properties of aqueous sodium chloride near its vapour pressure are presented. The equations are functions of temperature and concentration, and may be used to estimate aqueous sodium chloride's solubility, density, vapour pressure, specific enthalpy and entropy. They are valid for temperatures from 0 to 300°C, and concentrations extending to saturation with suitable accuracy. The thermodynamic equations are represented graphically and compared with published experimental data. These equations should prove to be a useful tool for modeling desalination equipment, particularly distillation processes.     

7-(Dialkylamino)coumarin-4-yl]methyl-Caged Compounds as Ultrafast and Effective Long-Wavelength Phototriggers of 8-Bromo-Substituted Cyclic Nucleotides

[7-(Dimethylamino)coumarin-4-yl]methyl (DMACM) and [7-(diethylamino)coumarin-4-yl]methyl (DEACM) esters of 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) and 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) are described as novel caged compounds for 8-bromo-substituted cyclic nucleotides. Synthesis is accomplished by treatment of the free acids of the cyclic nucleotides with the corresponding 7(dialkylamino)-substituted 4(diazomethyl)coumarins. Irradiation of the DMACM- and DEACM-caged cyclic nucleotides with UV light stimulates the release of the cyclic nucleotides within roughly a nanosecond. The new caged compounds are resistant to hydrolysis in aqueous buffers and exhibit long-wavelength absorption properties with maxima at 400 nm, high extinction coefficients, and high quantum yields (0.15-0.31). Their favorable properties render these compounds the most efficient and rapid phototriggers of 8-bromo-substituted cyclic nucleotides known. The usefulness of the compounds for physiological studies under nondamaging light conditions was examined in HEK293 cells expressing the alpha subunit of the cyclic-nucleotide-gated (CNG) channel of cone photoreceptors (CNGA3) and of olfactory neurons (CNGA2) by using confocal laser scanning microscopy and the patch clamp technique.     

The chemical feeding ecology ofNeodiprion dubiosus schedl,N. rugifrons midd., andN. lecontei (Fitch) on jack pine (Pinus banksiana lamb.)

Two monophagous sawflies,Neodiprion dubiosus andN. rugifrons, actively avoid feeding on the current season's needles of jack pine,Pinus banksiana, while the polyphagousN. lecontei feeds indiscriminately on foliage of all age classes. Bioassay studies with needle extracts indicate thatN. dubiosus andN. rugifrons larval feeding preference is governed by a group of tricyclic diterpene resin acids. Resin acids commonly occur in needles of all ages; however, levopimaric, palustric, dehydroabietic, and neoabietic acids were at higher concentrations in the new needles.N. dubiosus was significantly deterred from feeding on 1-year-old foliage when treated with the pure resin acids, palustric and levopimaric, at 0.5 and 1.0 mg/ml MeOH.N. rugifrons larvae were deterred from feeding by pure dehydroabietic, neoabietic, and palustric acids at 1.0 mg/ml MeOH.     

An embedding approach for the design of state‐feedback tracking controllers for references with jumps

We study the problem of designing state‐feedback controllers to track time‐varying state trajectories that may exhibit jumps. Both plants and controllers considered are modeled as hybrid dynamical systems, which are systems with both continuous and discrete dynamics, given in terms of a flow set, a flow map, a jump set, and a jump map. Using recently developed tools for the study of stability in hybrid systems, we recast the tracking problem as the task of asymptotically stabilizing a set, the tracking set, and derive conditions for the design of state‐feedback tracking controllers with the property that the jump times of the plant coincide with those of the given reference trajectories. The resulting tracking controllers guarantee that solutions of the plant starting close to the reference trajectory stay close to it and that the difference between each solution of the controlled plant and the reference trajectory converges to zero asymptotically. Constructive conditions for tracking control design in terms of LMIs are proposed for a class of hybrid systems with linear maps and input‐triggered jumps. The results are illustrated by various examples. Copyright © 2013 John Wiley & Sons, Ltd.     

Manipulating the microstructure and rheology in polymer‐organoclay composites

A series of nanocomposites prepared by melt‐blending of cloisite‐based organoclays with poly(ethylene‐vinylacetate) (EVA) and neutralized poly (ethylene‐methacrylic acid) (EMA) copolymers were investigated via DSC, small‐angle X‐ray scattering (SAXS), and rheological techniques. SAXS results indicated partial clay exfoliation in all samples. In both EMA and EVA systems, the nominal melting temperature T_m and bulk crystallinity are not significantly affected by the presence of organoclays, suggesting that clay particles are predominantly confined in the amorphous phase. In rheological measurements (above T_m), the EVA‐clay system demonstrated a solid‐like rheological behavior under the small‐strain oscillatory shear, yet it was able to yield and flow under a steady shear, which is the characteristic of physical crosslinking. In contrast, the EMA‐clay system exhibited a melt‐like rheological behavior, where the influence of organoclay on the thermorheological behavior of the EMA composite was quite minimal. We propose that the carbonyl groups of vinylacetate in EVA interact with the clay surface, resulting in a strong physically crosslinking like interaction in the melt. On the other hand, the interaction between EMA and clay is weak because of repulsion between carboxyl anions and negatively charged clay surface.     

Heterogeneous reactions of polymers: 4. Melting behaviour of heterogeneously chlorinated and sulphonated polyethylenes

The melting behaviour of heterogeneously chlorinated and sulphonated high-density polyethylene was studied by differential scanning calorimetry. It was found that an increase in T_m takes place at high degrees of substitution in the amorphous phase. For sulphonated polyethylenes the increase in T_m was also dependent on the type of the counterion. The effect is interpreted as a decrease in configurational entropy upon fusion due to the restraints that the highly chlorinated and sulphonated amorphous regions impose on the adjacent crystallites.     

Relationship between structure and dynamic mechanical properties of a carbon nanofiber reinforced elastomeric nanocomposite

The tensile and dynamic mechanical properties of a nanocomposite, containing modified carbon nanofibers (MCNFs) homogenously dispersed in an elastomeric ethylene/propylene (EP) copolymer semicrystalline matrix (84.3 wt% P), have been correlated with the structure development. These properties were characterized by in situ synchrotron X-ray diffraction during stretching, dynamic mechanical analysis and X-ray analysis techniques over a wide temperature range. Upon sequential drawing, the tensile strength of the nanocomposite film was notably higher than that of the unfilled polymer even though both samples exhibited a similar amount of crystal fraction and the same degree of crystal orientation, revealing the effect of nanofiller reinforcement in the semicrystalline matrix. The mechanical spectra of the 10 wt% MCNF filled samples in both stretched and non-stretched states showed broadening of the elastic modulus at high temperatures, where the corresponding crystallinity index also decreased. It is conceivable that a significant fraction of chain orientation is induced in the vicinity of the nanofillers during stretching, and these stretched chains with reduced mobility significantly enhance the thermal mechanical properties.