Cyber vulnerability maintenance policies that address the incomplete nature of inspection

In cybersecurity, incomplete inspection, resulting mainly from computers being turned off during the scan, leads to a challenge for scheduling maintenance actions. This article proposes the application of partially observable decision processes to derive cost‐effective cyber maintenance actions that minimize total costs. We consider several types of hosts having vulnerabilities at various levels of severity. The maintenance cost structure in our proposed model consists of the direct costs of maintenance actions in addition to potential incident costs associated with different security states. To assess the benefits of optimal policies obtained from partially observable Markov decision processes, we use real‐world data from a major university. Compared with alternative policies using simulations, the optimal control policies can significantly reduce expected maintenance expenditures per host and relatively quickly mitigate the most important vulnerabilities.     

Synthesis and crystal structure of (5-amino-4-carboxamidoimidazol-1-yl) acetamide,a possible PDE inhibitor

The crystal structure of 2-(5-amino-4-carboxamidoimidazol-1-yl)acetamide has been determined from X-ray diffractometric data, and refined to anR-value of 0.057 with 1179 observed reflections. Intramolecular hydrogen bonding between the 5-amino group and the vicinal carboxamide moiety stabilizes the molecular conformation and forms an extended planar structural pattern.     

DMSO–POCl3: a reagent for methylthiolation of imidazo[1,2-a]pyridines and other imidazo-fused heterocycles

A practical and metal free method for methylthiolation of imidazo[1,2-a]pyridines and other imidazo-fused heterocycles using DMSO–POCl₃ complex is reported. The reactions are carried out at room temperature that give the corresponding methylthiolated products in good to excellent yield. Further, its application to indole has been demonstrated.     

Any two irreducible Markov chains are finitarily orbit equivalent

Two invertible dynamical systems (X, gA, μ, T) and (Y, ℬ, ν, S), where X, Y are metrizable spaces and T, S are homeomorphisms on X and Y, are said to be finitarily orbit equivalent if there exists an invertible measure preserving mapping ϕ from a subset X ₀ of X of full measure to a subset Y ₀ of Y of full measure such that ϕ|x ₀ is continuous in the relative topology on X ₀, ϕ ⁻¹|Y ₀ is continuous in the relative topology on Y ₀ and ϕ(Orb _T (x)) = Orb _Sϕ (x) for μ-a.e. x ∈ X. In this article a finitary orbit equivalence mapping is shown to exist between any two irreducible Markov chains.     

Structure of de-oxy corticosterone-21-hemisuccinate

Synthetic glucocorticoid de-oxy corticosterone-21-hemisuccinate crystallizes in the monoclinic space group C2, with a = 21.896(2), b = 7.596(3) and c = 14.291(3) Å, Z = 4. Ring A is a distorted half chair, ring B and C are in the chair configuration and ring D is in the 14-half chair configuration. The ring junctions B/C and C/D are both trans. The molecule as a whole is slightly convex towards the -side, with an angle of 18.4(2)° between the C(10)--C(19) and C(13)--C(18) vectors. In addition to packing and stacking interaction, intermolecular hydrogen bonding plays an important role in structural association. The X-ray structure determination of the title compound was undertaken to study its high binding affinity to serum protein like globulin.     

2'-deoxycytidines carrying amino and thiol functionality: synthesis and incorporation by Vent (exo-) polymerase

[reaction: see text] The synthesis of 2'-deoxycytidine nucleosides bearing amino and thiol groups appended to the 5-position of the nucleobase via a butynyl linker is described. The corresponding triphosphates were then synthesized from the nucleoside and incorporated into oligonucleotides by Vent (exo(-)) DNA polymerase. The ability of Vent (exo(-)) polymerase to amplify oligonucleotides containing these functionalized cytidine derivatives in a polymerase chain reaction (PCR) was demonstrated for the amino-functionalized derivative.     

Potentiodynamic polarization studies on amorphous Zr46.75Ti8.25Cu7.5Ni10Be27.5, Zr65Cu17.5Ni10Al7.5, Zr67Ni33 and Ti60Ni40 in aqueous HNO3 solutions

Potentiodynamic polarization studies were carried out on virgin specimens of Zr-based bulk amorphous alloys Zr_46.75Ti_8.25Cu_7.5Ni₁₀Be_27.5 and Zr₆₅Cu_17.5Ni₁₀Al_7.5, and conventional-type binary amorphous alloys Zr₆₇Ni₃₃ and Ti₆₀Ni₄₀ in solutions of 0.2 M, 0.5 M and 1.0 M HNO₃ at room temperature. The values of the corrosion current density (I_corr) for the bulk amorphous alloy Zr_46.75Ti_8.25Cu_7.5Ni₁₀Be_27.5 were found to be comparable with those of Zr₆₅Cu_17.5Ni₁₀Al_7.5 in 0.2 M and 0.5 M HNO₃, but the value of I_corr for the former was almost three times more than that of the latter in 1.0 M HNO₃. In the case of conventional binary amorphous alloys, Ti₆₀Ni₄₀ showed lower value of I_corr as compared to Zr₆₇Ni₃₃ in 0.5 M and 1.0 M HNO₃ and a comparable value of I_corr in 0.2 M HNO₃. In general, the binary Ti₆₀Ni₄₀ displayed the best corrosion resistance among all the alloys in all the cases and the corrosion current density (I_corr) for all the alloys was found to increase with the increasing concentration of nitric acid. It is noticed that the bulk amorphous alloys do not possess superior corrosion resistance as compared to conventional binary amorphous alloys in aqueous HNO₃ solutions. The observed differences in their corrosion behavior are attributed to different alloy constituents and composition of the alloys investigated.     

K-K electron capture from adenine and CO2 molecule by fast carbon ions using KLL-Auger electron technique

The experimental measurement of total electron transfer cross section in Bragg peak energy region is important to understand energy loss in the biomolecular system. In this study, we have measured state selective, K-K electron capture and K-ionization cross sections for adenine (C ₅H ₅N ₅) in collisions with fast (2.5–5 MeV/u) C ions. These are compared with the data for smaller gas molecule, CO ₂. These are derived from a study of the KLL-Auger electron emission yields as a function projectile charge state. The K-ionization cross-section (σ_KI) data are compared with the ECUSAR (united and separated atom [USA] approximation with energy loss [E], Coulomb deflection [C], and relativistic [R] corrections) model calculation. The measured σ_KI data and the calculations are in good agreement. The K-K transfer cross-section (σ_K−K) data are compared with the CPSSR (perturbed stationary state [PSS] with Coulomb deflection [C] and relativistic corrections [R]) calculation that underestimates the measured data for such symmetric collision system. The energy dependence of σ_K−K for adenine is found to be flat in contrast to a sharp variation predicted by the model. The K-transfer cross section is found to be substantial fraction of the K-ionization.