Random security scheme selection for mobile transactions

Security in a mobile communication environment is always a matter for concern, even after deploying many security techniques at device, network, and application levels. The end-to-end security for mobile applications can be made robust by developing dynamic schemes at application level which makes use of the existing security techniques varying in terms of space, time, and attacks complexities. In this paper we present a security techniques selection scheme for mobile transactions, called the Transactions-Based Security Scheme (TBSS). The TBSS uses intelligence to study, and analyzes the security implications of transactions under execution based on certain criterion such as user behaviors, transaction sensitivity levels, and credibility factors computed over the previous transactions by the users, network vulnerability, and device characteristics. The TBSS identifies a suitable level of security techniques from the repository, which consists of symmetric, and asymmetric types of security algorithms arranged in three complexity levels, covering various encryption/decryption techniques, digital signature schemes, andhashing techniques. From this identified level, one of the techniques is deployed randomly. The results shows that, there is a considerable reduction in security cost compared to static schemes, which employ pre-fixed security techniques to secure the transactions data.

Modelling boreal forest CO2 exchange and seasonality

Man-induced climate change has raised the need to predict the future climate and its feedback to vegetation. These are studied with global climate models; to ensure the reliability of these predictions, it is important to have a biosphere description that is based upon the latest scientific knowledge. This work concentrates on the modelling of the CO2 exchange of the boreal coniferous forest, studying also the factors controlling its growing season and how these can be used in modelling. In addition, the modelling of CO2 gas exchange at several scales was studied. A canopy-level CO2 gas exchange model was developed based on the biochemical photosynthesis model. This model was first parameterized using CO2 exchange data obtained by eddy covariance (EC) measurements from a Scots pine forest at Sodankylä. The results were compared with a semi-empirical model that was also parameterized using EC measurements. Both of the models gave satisfactory results. The biochemical canopy-level model was further parameterized at three other coniferous forest sites located in Finland and Sweden. At all the sites, the two most important biochemical model parameters showed seasonal behaviour, i.e., their temperature responses changed according to the season. Modelling results were improved when these changeover dates were related to temperature indices. During summer-time the values of the biochemical model parameters were similar at all the four sites. Different control factors for CO2 gas exchange were studied at the four coniferous forests, including how well these factors can be used to predict the initiation and cessation of the CO2 uptake. Temperature indices, atmospheric CO2 concentration, surface albedo and chlorophyll fluorescence (CF) were all found to be useful and have predictive power. In addition, a detailed simulation study of leaf stomata in order to separate physical and biochemical processes was performed. The simulation study brought to light the relative contribution and importance of the physical transport processes. The results of this work can be used in improving CO2 gas exchange models in boreal coniferous forests. The meteorological and biological variables that represent the seasonal cycle were studied, and a method for incorporating this cycle into a biochemical canopy-level model was introduced.

Disallowed Ramachandran Conformations of Amino Acid Residues in Protein Structures

An analysis of the nature and distribution of disallowed Ramachandran conformations of amino acid residues observed in high resolution protein crystal structures has been carried out. A data set consisting of 110 high resolution, non-homologous, protein crystal structures from the Brookhaven Protein Data Bank was examined. The data set consisted of a total of 18,708 non-Gly residues, which were characterized on the basis of their backbone dihedral angles (φ, ψ). Residues falling outside the defined “broad allowed limits” on the Ramachandran map were chosen and the reportedB-factor value of the α-carbon atom was used to further select well defined disallowed conformations. The conformations of the selected 66 disallowed residues clustered in distinct regions of the Ramachandran map indicating that specific φ, ψ angle distortions are preferred under compulsions imposed by local constraints. The distribution of various amino acid residues in the disallowed residue data set showed a predominance of small polar/charged residues, with bulky hydrophobic residues being infrequent. As a further check, for all the 66 cases non-hydrogen van der Waals short contacts in the protein structures were evaluated and compared with the ideal “Ala-dipeptide” constructed using disallowed dihedral angle (φ, ψ) values. The analysis reveals that short contacts are eliminated in most cases by local distortions of bond angles. An analysis of the conformation of the identified disallowed residues in related protein structures reveals instances of conservation of unusual stereochemistry.

Family of Mixed-Valence Oxovanadium(IV/V) Dinuclear Entities Incorporating N4O3-Coordinating Heptadentate Ligands: Synthesis, Structure, and EPR Spectra

Dinuclear ((VVV)-V-IV) oxophenoxovanadates of general formula [V2O3L] have been synthesized in excellent yields by reacting bis(acetylacetonato)oxovanadium(IV) with H3L in a 2:1 ratio in acetone under an N-2 atmosphere. Here L3- is the deprotonated form of 2,6-bis[{{(2-hydroxybenzyl)(N',N'-(dimethylamino)ethyl)}amino}methyl]-4-methylphenol (H3L1), 2,6-bis[{{(5-methyl-2-hydroxybenzyl)(N',N'-(dimethylamino)ethyl)}amino}methyl]-4-methylphenol (H3L2) 2,6-bis[ {{(5-tert-butyl-2-hydroxybenzyl)(N',N'-(dimethylamino)ethyl)}amino}methyl]-4-methylphenoI (H3L3), 2,6-bis[{{(5-chloro-2-hydroxybenzyl)(N',N'-(dimethylamino)ethyl)}amino}methyl]-4-methylphenol (H3L4) , 2,6-bis[{{(5-bromo-2-hydroxybenzyl)(N',N'-(dimethylamino)ethyl)}amino}methyl]-4-methylphenol (H3L5), or 2,6-bis[{{(5-methoxy-2-hydroxybenzyl)(N',N'-(dimethylamino)ethyl)}amino}methyl]-4-methylphenol (H3L6). In [V2O3L1], both the metal atoms have distorted octahedral geometry. The relative disposition of two terminal V=O groups in the complex is essentially cis. The O=V...V=O torsion angle is 24.6(2)degrees. The V-O-oxo-V and V-O-phenoxo-V angles are 117.5(4) and 93.4(3)degrees, respectively. The V...V bond distance is 3.173(5) Angstrom. X-ray crystallography, IR, UV-vis, and H-1 and V-51 NMR measurements show that the mixed-valence complexes contain two indistinguishable vanadium atoms (type 111). The thermal ellipsoids of O2, O4, C10, C14, and C15 also suggests a type III complex in the solid state. EPR spectra of solid complexes at 77 K display a single line indicating the localization of the odd electron (3d(xy)(1)). Valence localization at 77 K is also consistent with the V-51 hyperfine structure of the axial EPR spectra (3d(xy)(1) ground state) of the complexes in frozen (77 K) dichloromethane solution: S = 1/2, g(parallel to) similar to 1.94, g(perpendicular to) similar to 1.98, A(parallel to) similar to 166 x 10(-4) cm(-1), and A(perpendicular to) similar to 68 x 10(-4) cm(-1). In contrast isotropic room-temperature solution spectra of the family have 15 hyperfine lines (g(iso) similar to 1.974 and A(iso) similar to 50 x 10(-4) cm(-1)) revealing that the unpaired electron is delocalized between the metal centers. Crystal data for the [V2O3L1].CH2Cl2 complex are as follows: chemical formula, C32H43O6N4C12V2; crystal system, monoclinic; space group, C2/c; a = 18.461(4), b = 17.230(3), c = 13.700(3) Angstrom; beta = 117.88(3)degrees; Z = 8.

Topological analysis off charge density distribution in concomitant polymorphs of 3-acetylcoumarin, a case off packing polymorphism

Detailed investigation of the charge density distribution in concomitant polymorphs of 3-acetylcoumarin in terms of experimental and theoretical densities shows significant differences in the intermolecular features when analyzed based on the topological properties via the quantum theory of atoms in molecules. The two forms, triclinic and monoclinic (Form A and Form B), pack in the crystal lattice via weak C-H---O and C-H---pi interactions. Form A results in a head-to-head molecular stack, while Form B generates a head-to-tail stack. Form A crystallizes in PI (Z' = 2) and Form B crystallizes in P2(1)/n (Z = 1). The electron density maps of the polymorphs demonstrate the differences in the nature of the charge density distribution in general. The charges derived from experimental and theoretical analysis show significant differences with respect to the polymorphic forms. The molecular dipole moments differ significantly for the two forms. The lattice energies evaluated at the HF and DFT (B3LYP) methods with 6-31G** basis set for the two forms clearly suggest that Form A is the thermodynamically stable form as compared to Form B. Mapping of electrostatic potential over the molecular surface shows dominant variations in the electronegative region, which bring out the differences between the two forms.

Studies on removal of metal ions and sulphate reduction using rice husk and Desulfotomaculum nigrificans with reference to remediation of acid mine drainage

The utility of rice husk as an adsorbent for metal ions such as iron, zinc and copper from acid mine water was assessed. The adsorption isotherms exhibited Langmuirian behavior and were endothermic in nature. The free energy values for adsorption of the chosen metal ions onto rice husk were found to be highly negative attesting to favorable interaction. Over 99% Fe3+, 98% of Fe2+ and Zn2+ and 95% Cu2+ uptake was achieved from acid mine water, with a concomitant increase in the pH value by two units using rice husk. The remediation studies carried out on acid mine water and simulated acid mine water pretreated with rice husk indicated successful growth of Desulfotomaculum nigrificans (D. nigrificans). The amount of sulphate bioreduction in acid mine water at an initial pH of 5.3 was enhanced by D. nigrificans from 21% to 40% in the presence of rice husk filtrate supplemented with carbon and nitrogen. In simulated acid mine water with fortified husk filtrate, the sulphate reduction was even more extensive, with an enhancement to 73%. Concurrently, almost 90% Fe2+, 89% Zn2+ and 75% Cu2+ bioremoval was attained from simulated acid mine water. Metal adsorption by rice husk was confirmed in desorption experiments in which almost complete removal of metal ions from the rice husk was achieved after two elutions using 1 M HCl. The possible mechanisms of metal ion adsorption onto rice husk and sulphate reduction using D. nigrificans are discussed.

Phase relationships in the system Ni-W-O and thermodynamic properties of NiWO,

The phase diagram of the Ni-W-O system at 1200 K was established by metallographic and X-ray identification of the phases present after equilibration at controlled oxygen potentials. The oxygen partial pressures over the samples were fixed by metered streams of CO+CO2 gas mixtures. There was only one ternary oxide, nickel tungstate (NiWO4), in the Ni-W-O system at a total pressure of 1 atm, and this compound decomposed to a mixture of Ni+WO2.72 on lowering the oxygen potential. The Gibbs' free energy of formation of NiWO4 was determined from the measurement of the e.m.f. of the solid oxide galvanic cell, Pt, Ni+NiWO4+WO2.72/CaO-ZrO2/Ni+NiO, Pt and thermodynamic properties of tungsten and nickel oxides available in the literature. For the reaction, NiO(s)+WO3(s)rarrNiWO4(s) DeltaG°=–10500–0.708 T (±250) cal mol–1.

Noble metal ionic sites for catalytic hydrogen combustion: spectroscopic insights

A catalytic hydrogen combustion reaction was carried out over noble metal catalysts substituted in ZrO2 and TiO2 in ionic form. The catalysts were synthesized by the solution combustion technique. The compounds showed high activity and CO tolerance for the reaction. The activity of Pd and Pt ion substituted TiO2 was comparable and was higher than Pd and Pt ion substituted ZrO2. The mechanisms of the reaction over the two supports were proposed by making use of the X-ray photoelectron spectroscopy and FT infrared spectroscopic observations. The reaction over ZrO2 supported catalysts was proposed to take place by the utilization of the surface hydroxyl groups while the reaction over TiO2 supported catalysts was hypothesized to be a hybrid mechanism utilizing surface hydroxyl groups and the lattice oxygen.

Molecular structure of Lantadene-B&C, triterpenoids ofantana camara, red variety: Lantadene-B, 22β-angeloyloxy-3-oxoolean-12-en-28-oic acid; Lantadene-C, 22 β-(S)-2′-methyl butanoyloxy-3-oxoolean-12-en-28-oic acid

(I)Lantadene-B: C35H52O5,M r =552.80, MonoclinicC2,a=25.65(1),b=6.819(9),c=18.75(1) Å,beta=100.61(9),V=3223(5) Å3,Z=4,D x =1.14 g cm–3 CuKagr (lambda=1.5418A),mgr=5.5 cm–1,F(000)=1208,R=0.118,wR=0.132 for 1527 observed reflections withF o ge2sgr(F o ). (II)Lantadene-C: C35H54O5·CH3OH,Mr=586.85, Monoclinic,P21,a=9.822(3),b=10.909(3),c=16.120(8)Å,beta=99.82(4),V=1702(1)Å3,Z=2,D x =1.145 g cm–3, MoKagr (lambda=0.7107Å), mgr=0.708 cm–1 F(000)=644,R=0.098, wR=0.094 for 1073 observed reflections. The rings A, B, C, D, and E aretrans, trans, trans, cis fused and are in chair, chair, sofa, half-chair, chair conformations, respectively, in both the structures. In the unit cell the molecules are stabilized by O-HctdotO hydrogen bonds in both the structures, however an additional C-HctdotO interaction is observed in the case of Lantadene-C.

Hydrolytic degradation and diffusion studies on a polyphosphate ester

A polyphosphate ester was synthesized by interfacial polycondensation of bisphenol-A and phenylphosphorodichloridate. Accelerated hydrolytic degradation studies were conducted under alkaline conditions. The effect of concentration of alkali and temperature were monitored. The rate of degradation reached a maximum value at 6 molar sodium hydroxide solution and then reduced. The activation energy for hydrolytic degradation was found to be 45 kcal/mol. Diffusion of alkali into the polymer pellet was studied at various concentrations of alkali and at various temperatures. The rate of diffusion also attained a maximum at 6M NaOH and the activation energy for diffusion process was found to be 12 kcal/mol. (C) 2002 John Wiley Sons, Inc.

Very large array detection of radio recombination lines from the radio nucleus of NGC 253: Ionization by a weak active galactic nucleus, an obscured super star cluster, or a compact supernova remnant?

We have imaged the H92alpha and H75alpha radio recombination line (RRL) emissions from the starburst galaxy NGC 253 with a resolution of similar to4 pc. The peak of the RRL emission at both frequencies coincides with the unresolved radio nucleus. Both lines observed toward the nucleus are extremely wide, with FWHMs of similar to200 km s(-1). Modeling the RRL and radio continuum data for the radio nucleus shows that the lines arise in gas whose density is similar to10(4) cm(-3) and mass is a few thousand M., which requires an ionizing flux of (6-20) x 10(51) photons s(-1). We consider a supernova remnant (SNR) expanding in a dense medium, a star cluster, and also an active galactic nucleus (AGN) as potential ionizing sources. Based on dynamical arguments, we rule out an SNR as a viable ionizing source. A star cluster model is considered, and the dynamics of the ionized gas in a stellar-wind driven structure are investigated. Such a model is only consistent with the properties of the ionized gas for a cluster younger than similar to10(5) yr. The existence of such a young cluster at the nucleus seems improbable. The third model assumes the ionizing source to be an AGN at the nucleus. In this model, it is shown that the observed X-ray flux is too weak to account for the required ionizing photon flux. However, the ionization requirement can be explained if the accretion disk is assumed to have a big blue bump in its spectrum. Hence, we favor an AGN at the nucleus as the source responsible for ionizing the observed RRLs. A hybrid model consisting of an inner advection-dominated accretion flow disk and an outer thin disk is suggested, which could explain the radio, UV, and X-ray luminosities of the nucleus.

Damping and synchronising torques contributed by a voltage regulator to a synchronous generator: a quantitative assessment

In the paper, the total damping and synchronising torques, which determine the dynamic stability of a synchronous generator in a power system, have been traced to their origin. The positive and negative components released or consumed by the voltage regulator, and by the various windings of the machine, have been isolated, with the object of making a quantitative assessment of the effects of various gains and time constants on the dynamic stability of a synchronous machine under different operating conditions. The analysis is based on the properties of quadratic invariance in tensor calculus. An alternative solution by network analysis has also been provided to establish the validity of the tensor approach.

Anomalous triple gauge boson couplings in e(-)e(+) -> gamma gamma for noncommutative standard model

We investigate e(+)e(-) -> gamma gamma process within the Seiberg-Witten expanded noncommutative standard model (NCSM) scenario in the presence of anomalous triple gauge boson couplings. This study is done with and without initial beam polarization and we restrict ourselves to leading order effects of noncommutativity i.e. O(Theta). The noncommutative (NC) corrections are sensitive to the electric component ((Theta) over bar (E)) of NC parameter. We include the effects of Earth's rotation in our analysis. This study is done by investigating the effects of noncommutativity on different time averaged cross section observables. We have also defined forward backward asymmetries which will be exclusively sensitive to anomalous couplings. We have looked into the sensitivity of these couplings at future experiments at the International Linear Collider (ILC). This analysis is done under realistic ILC conditions with the center of mass energy (cm.) root s = 800 GeV and integrated luminosity L = 500 fb(-1). The scale of noncommutativity is assumed to be Lambda = 1 TeV. The limits on anomalous couplings of the order 10(-1) from forward backward asymmetries while much stringent limits of the order 10(-2) from total cross section are obtained if no signal beyond SM is seen. (C) 2012 Elsevier B.V. All rights reserved.