SEIQRS model for the transmission of malicious objects in computer network

Susceptible (S) – exposed (E) – infectious (I) – quarantined (Q) – recovered (R) model for the transmission of malicious objects in computer network is formulated. Thresholds, equilibria, and their stability are also found with cyber mass action incidence. Threshold R_cq determines the outcome of the disease. If R_cq ? 1, the infected fraction of the nodes disappear so the disease die out, while if R_cq > 1, the infected fraction persists and the feasible region is an asymptotic stability region for the endemic equilibrium state. Numerical methods are employed to solve and simulate the system of equations developed. The effect of quarantine on recovered nodes is analyzed. We have also analyzed the behavior of the susceptible, exposed, infected, quarantine, and recovered nodes in the computer network.     

Fixed period of temporary immunity after run of anti-malicious software on computer nodes

SIRS epidemic model has been developed with a fixed period of temporary immunity, following temporary recovery from the infection of malicious objects in place of an exponentially distributed period of temporary immunity. When a node is recovered from the infected class, it recovers temporarily, acquiring temporary immunity with probability p (0  p  1) and dies from the attack of malicious object with probability (1 − p). Temporary immunity is observed in the computer network when anti-malicious software is run after a node gets affected by a malicious object(s). The model consists of a set of integro-differential equations. The stability of the results is stated in terms of threshold parameter. It has been observed that the endemic equilibrium for this model may be unstable thus giving an example of a generalization which leads to new possibilities for the behavior of the model. Numerically it has been verified that the endemic equilibrium is not asymptotically stable for all parameter values.     

Multistep transitions in collagens

It is well known that collagens exist in triple-helical form, and, on average, the individual chains have glycine at every third place. Collagens from different sources vary in distributions of other amino acids. They could also be different in the distribution of defects, which are generally nonhelical regions of low stability. Varying lengths of individual chains in the triple-helical system can also contribute to this variability. All these variations manifest themselves in the creation of a transition profile with undulations that are indicative of a multiphasic nature. In the present communication, we try to understand this variability by using essentially the Zimm and Bragg approach and suitably amending it for a triple-helical system. Factors that contribute to the multiphasic nature are incorporated into the transition model and discussed. Results obtained for collagen types I, II, III, V_x, V_y, and XI are in agreement with the experimental measurements. Transitions in the first three types can be interpreted on the basis of two-phase theory. Nucleation parameters, which are indicative of the sharpness of transition, are interpreted in terms of stability and possible amino acid composition.     

Vibrational Dynamics of Poly(l-asparagine)

The normal modes and their dispersions for poly(l-asparagine) (PLN) in the α-helical form have been obtained in a reduced zone scheme with Wilson's GF matrix method as modified by Higgs. The results indicate that the modes below 1350 cm^?1 show appreciable dispersion. Optically active frequencies corresponding to the zone center and zone boundary are identified and discussed. Some of the characteristic features of the dispersion curves are repulsion accompanied by an exchange of character and von Hove singularities. Amide modes, side chain modes, and mixed modes are reported. The heat capacity calculated from the dispersion curves via density-of-states using Debye's relation is compared with the experimental data in the temperature range of 220–390 K.     

TAGE iterative algorithm and nonpolynomial spline basis for the solution of nonlinear singular second order ordinary differential equations

In the present paper, we discuss three point difference method based on nonpolynomial spline basis for the second order ordinary differential equation. Difference schemes are derived for linear and nonlinear case and are used to solve via two parameter alternating group explicit iterative algorithm. The schemes have a fourth and second order of uniform convergence for the choice of the parameters involved in the method. Computational results are presented comparing the two methods in terms of accuracy and execution times. The results indicate the advantage of using parallel implementation of the new method.     

Phonons and their dispersion in poly(S-benzyl-L-cysteine)

Poly(S-benzyl-L -cysteine) (PBLC) is a S-benzyl derivative of the natural amino acid poly(L -cysteine). Its normal modes and their dispersion in antiparallel β-sheet conformation have been obtained within the first Brillouin zone using Wilson's G.F. matrix method, as modified by Higgs for an infinite polymeric chain. The zone center frequencies and the Urey Bradley force field have been obtained by “best fitting” the observed Fourier transform IR (FTIR) absorption bands. The characteristic features of dispersion curves such as crossing, repulsion, and exchange of character are discussed. Predictive values of heat capacity in the temperature range of 50–500 K are reported. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3269–3287, 1999     

Phosphotriester approach to the synthesis of α-glucosylated mono- and diphosphatidyl glycerols: bacterial cell-wall components

Two bifunctional phosphorylating agents, 2,2,2-tribromoethyl and 2-chlorophenyl phosphorodichloridate, were used with 1,2,4-triazole to assemble phosphotriester derivatives of protected α-glucosyl mono- and diphosphatidyl glycerols. Benzyl, allyl and pivaloyl groups were used for the protection of the hydroxyl functions of the glucose and glycerol moieties, respectively. The merits of the pivaloyl group are discussed. Finally, special attention is paid to the conversion of the phosphotriesters into the required phosphodiester functions.