False targets efficiency in defense strategy

The paper analyzes the efficiency of deploying false targets as part of a defense strategy. It is assumed that the defender has a single object that can be destroyed by the attacker. The defender distributes its resource between deploying false targets and protecting the object from outside attacks. The attacker cannot distinguish the false targets from the defended object (genuine target). Therefore the attacker has no preferences for attacking one target rather than another target. The defender decides how many false targets to deploy whereas the attacker decides how many targets to attack. The article assumes that both the defender and attacker have complete information and full rationality. The optimal number of false targets and the attacked targets are obtained for the case of fixed and variable resources of the defender and the attacker as solutions of a non-cooperative game between the two agents.     

Analytic analysis of irregular discrete universes

In this work we investigate the dynamics of cosmological models with spherical topology containing up to 600 Schwarzschild black holes arranged in an irregular manner. We solve the field equations by tessellating the 3-sphere into eight identical cells, each having a single edge which is shared by all cells. The shared edge is enforced to be locally rotationally symmetric, thereby allowing for solving the dynamics to high accuracy along this edge. Each cell will then carry an identical (up to parity) configuration which can however have an arbitrarily random distribution. The dynamics of such models is compared to that of previous works on regularly distributed black holes as well as with the standard isotropic dust models of the FLRW type. The irregular models are shown to have richer dynamics than that of the regular models. The randomization of the distribution of the black holes is done both without bias and also with a certain clustering bias. The geometry of the initial configuration of our models is shown to be qualitatively different from the regular case in the way it approaches the isotropic model.     

Temperature dependence of the inhibition of positronium by chlorine-substituted hydrocarbons in non-polar liquids

Positron annihilation lifetime spectra were measured for solutions of 1,2,3,5-C₆H₂Cl₄ in hexane, toluene, m-xylene and mesitylene, CCl₄ in hexane and toluene, and C₂HCl₃ in n-hexane for concentrations below 1 M and at various temperatures between ?30°C and 67°C. The Ps inhibition by C₆H₂Cl₄ was roughly 14 times stronger at ?30°C than at 67°C in toluene, m-xylene, and mesitylene, while that of CCl₄ displayed hardly any temperature dependence in hexane and toluene. Previously, the Ps inhibition by C₆H₂Cl₄ in various liquids at 20°C was explained by a competition between electron pick off by the positron from C₆H₂Cl₄^? formed by electron scavenging in the positron spur, and dehalogenation of the same anion at picosecond times after the spur formation. Three effects might reasonably explain the strong temperature dependence of the Ps inhibition of C₆H₂Cl₄: (1) The dechlorination time of C₆H₂Cl₄^? might be much shorter at low than at high temperatures. (2) The positron mobility might decrease very strongly with decreasing temperature. (3) Positrons possibly trapped on C₆H₂Cl₄ might thermally detach at high but not at low temperatures.     

Ru(II)-catalyzed cascade reactions in stereocontrolled construction of rigid as-indacene-bridged bis(alpha-amino acid) derivatives

The key construction in the preparation of as-indacene-bridged bis(alpha-amino acid) derivatives was effected by a Ru(II)-catalyzed RCM cascade reaction of appropriately substituted triynes. The latter were available after stepwise and stereocontrolled alkynylations of (2R)-2,5-dihydro-2-isopropyl-3,6-dimethoxypyrazine as chiral auxiliary. The regio- and stereochemical transformations have been verified by a single-crystal X-ray analysis.     

On the Foundation of the Principle of Relativity

The relation of the special and the general principle of relativity to the principle of covariance, the principle of equivalence and Mach's principle, is discussed. In particular, the connection between Lorentz covariance and the special principle of relativity is illustrated by giving Lorentz covariant formulations of laws that violate the special principle of relativity: Ohm's law and what we call Aristotle's first and second laws. An Aristotelian universe in which all motion is relative to absolute space is considered. The first law: a free particle is at rest. The second law: force is proportional to velocity. Ohm's law: the current density is proportional to the electrical field strength. Neither of these laws fulfills the principle of relativity. The examples illustrate, in the context of Lorentz covariance and special relativity, Kretschmann's critique of founding Einstein's general principle of relativity on the principle of general covariance. A modification of the principle of covariance is suggested, which may serve as a restricted criterium for a physical law to satisfy Einstein's general principle of relativity. Other objections that have been raised to the validity of Einstein's general principle of relativity are based upon the preferred state of inertial frames in the general, as well as in the special theory, the existence of tidal effects in true gravitational fields, doubts as to the validity of Mach's principle, whether electromagnetic phenomena obey the principle, and, finally, the anisotropy of the cosmic background radiation. These objections are reviewed and discussed.     

Nanowires for surface enlargement of narrow-bore fused-silica tubing

A method for preparation of silica nanowires with dimensions of d = 10-100 nm, l = 5-500 nm, is described. The nanostructured material is an integral part of the inner surface of narrow bore fused-silica capillary tubing. The wire preparation method is based on a decomposition of 2-chloro-1,1,2-trifluoroethyl methyl ether at elevated temperature and pressure. The silica bulk material is rearranged via a sustained silica-hydrogen fluoride chemistry, and reaction mechanisms for this process are proposed. The method is suitable for preparing long lengths of tubing with the modified surface. It is our belief that the texture of the capillary wall with its increased surface area is useful for applications such as microreactions, catalysis, and high-resolution pressure and/or electrodriven open-tubular liquid chromatography.     

Global rotation

Global rotation in cosmological models is defined on an observational basis. A theorem is proved saying that, for rigid motion, the global rotation is equal to the ordinary local vorticity. The global rotation is calculated in the space-time homogeneous class III models, with Gödel's model as a special case. It is shown that, with the exception of Gödel's model, the rotation in these models becomes infinite for finite affine parameter values. In some directions the rotation changes sign and becomes infinite in a direction opposite to the local vorticity. The points of infinite rotation are identified as conjugate points along the null geodesies. The physical interpretation of the infinite rotation is discussed, and a comparison with the behavior of the area distance at conjugate points is given.     

The classical and relativistic concepts of mass

An elementary presentation is given of classical and relativistic collision dynamics based upon the principle of conservation of momentum. The concepts of mass are shown to be implicitly defined and their basic properties are rigorously derived and discussed. Luxons and tachyons are treated on the same footing as material particles.     

Stereoselective preparation of (RP)-8-hetaryladenosine-3',5'-cyclic phosphorothioic acids

Cyclic adenosine monophosphate (cAMP) has been converted into its 8-bromo derivative and 2'O-TBDMS protected before activation of the phosphoric acid moiety with a reagent generated in situ from oxalyl chloride and DMF. Further reactions with primary amines furnished corresponding phosphoramidates with high stereoselectivity at the phosphorus atom. Cross-coupling reactions with the 8-bromopurine yielded 8-hetaryl derivatives. X-Ray analyses showed the amidates to possess the (S(P))-configuration. Carbon disulfide effected thiylation under strongly basic conditions stereospecifically provided the (R(P))-phosphorothioic acids.