Defence and attack of systems with variable attacker system structure detection probability

A system consists of identical elements. The cumulative performance of these elements should meet a demand. The defender applies three types of defensive actions to reduce a damage associated with system performance reduction caused by an external attack: deploying separated redundant genuine system elements, deploying false elements, and protecting genuine elements. If the attacker cannot distinguish between genuine and false elements, he chooses a number of elements to attack and then selects the elements at random, distributing his resources equally across these elements. By obtaining intelligence data, the attacker can get full information about the system structure and identify false and unprotected genuine elements. The defender estimates the probability that the attacker can identify all system elements. This paper analyses the influence of this probability in a non-cooperative two-period minmax game between the defender and the attacker.     

Cross-country skiing motion equations,locomotive forces and mass scaling laws

This article presents differential equations for locomotive force and velocity during cross-country skiing. A muscle's work power is modelled. Thereafter, a locomotive force that depends on the skier's velocity is constructed. The external forces aerodynamic drag, friction forces and the force of gravity are incorporated in order to provide the equation of motion. Some allometric mass scaling relations are established and used to analyse the effect of a skier's mass on velocity. The model is tested by using a GPS instrument. We compare analytically and experimentally determined skiing distances and velocities as functions of time, and under different conditions. The article provides tools useful for practising athletes and coaches.     

The impact of disaster on the strategic interaction between company and government

A company allocates a resource between safety effort and production. The government earns taxes on production. The disaster probability is modeled as a contest between the disaster magnitude and the two players’ safety efforts. The model illustrates that safety efforts are strategic substitutes and inverse U shaped in the disaster magnitude. The company’s safety effort increases, and the government’s safety effort decreases, in taxation. Taxation can ameliorate companies’ free riding on governments’ safety efforts. With sufficiently large production, the government prefers, and the company does not prefer, raising taxation above 0%. For the government, an upper limit usually exists above which taxation cannot be profitably increased. The model shows how both or no players exert safety efforts when the disaster magnitude is small and large respectively, and how they free ride on each other’s safety efforts when the disaster magnitude is intermediate. The company free rides when the unit production cost is low so that the large profits outweigh the negative impact of the disaster. With endogenized taxation determined by the government, the tax rate decreases in the disaster magnitude, the unit production cost, the government’s unit cost of safety effort, and how the company is negatively affected by the disaster. The tax rate increases in the company’s resource and how the government is negatively affected by the disaster. The tax rate is weakly U shaped in the company’s unit safety effort. The model is illustrated with numerical examples and with the oil spill disasters by BP in 2010 and by Exxon Valdez in 1989.     

Submicron gold structures formed by atomic force microscopy lithography on thin films of poly(methyl methacrylate)

Thin films of poly(methyl methacrylate) (PMMA) (25 nm) deposited on gold coated glass substrates have been locally modified by exposure to biased atomic force microscopy (AFM) tips. Constant exposure currents in the range of 0.5–0.65 nA leads to removal of PMMA both by direct ablation and enhanced solubility in a developer solution. Possible mechanisms causing such modifications have been discussed. Submicron Au structures were formed by combining AFM lithography, involving localized removal of PMMA, with sputter deposition of gold and a lift-off process.     

Design, synthesis and characterization of a Pt-Gd metal-organic framework containing potentially catalytically active sites

The heterobimetallic metal-organic framework {[(BPDC)PtCl(2)](3)(Gd(H(2)O)(3))(2)}.5H(2)O (BPDC = 2,2'-bipyridine-5,5'-dicarboxylate) has been designed and synthesized by hydrothermal methods. The new coordination polymer contains subunits of (BPDC)PtCl(2) (1) where both N atoms of the BPDC ligand are attached to a square-planar Pt(II) center. The two remaining cis coordination sites at Pt(II) are occupied by chloride ions. The final structure (2) of the polymeric network is obtained when Gd(III) ions link together the (BPDC)PtCl(2) units, which are organized in sheets, into larger blocks. These blocks are stacked along the crystallographic [010] direction and are held together by a hydrogen bonding scheme that involves carboxylate oxygen atoms and water molecules in the coordination sphere of Gd. The coordination polymer 2 can be obtained in a single-step reaction or in a two-step synthesis where the corresponding Pt complex (1) was first synthesized followed by reacting 1 with Gd(NO(3))(3).6H(2)O. In situ high temperature powder X-ray diffraction shows that the crystalline coordination polymer transforms into an anhydrous modification at 100 degrees C. This modification is stable to 350 degrees C, at which temperature the structure starts to decompose. The coordination sphere around platinum in the polymer closely resembles organometallic Pt complexes that have been previously found to catalytically or stoichiometrically activate and functionalize hydrocarbon C-H bonds in homogeneous systems.     

Amine functionalised metal organic frameworks (MOFs) as adsorbents for carbon dioxide

Three different porous metal organic framework (MOF) materials have been prepared with and without uncoordinated amine functionalities inside the pores. The materials have been characterized and tested as adsorbents for carbon dioxide. At 298 K the materials adsorb significant amount of carbon dioxide, the amine functionalised adsorbents having the highest CO₂ adsorption capacities, the best adsorbing around 14 wt% CO₂ at 1.0 atm CO₂ pressure. At 25 atm CO₂ pressure, up to 60 wt% CO₂ can be adsorbed. At high pressures the CO₂ uptake is mostly dependent on the available surface area and pore volume of the material in question. For one of the iso-structural MOF pairs the introduction of amine functionality increases the differential adsorption enthalpy (from isosteric method) from 30 to around 50 kJ/mole at low CO₂ pressures, while the adsorption enthalpies reach the same level at increase pressures. The high pressure experimental results indicate that MOF based solid adsorbents can have a potential for use in pressure swing adsorption of carbon dioxide at elevated pressures.     

Electrochemical synthesis, structural characterization, and decomposition of rhenium oxoethoxide, Re4O4(OEt)12. Ligand influence on the structure and bonding in the high-valent tetranuclear planar rhenium alkoxide clusters

Anodic oxidation of rhenium in ethanol in the presence of LiCl as a conductive additive results with high yield in formation of a new oxoethoxide cluster, Re(4)O(4)(OEt)(12). The structure of the planar centrosymmetric metal-oxygen core of this molecule is composed of four edge-sharing Re(V)O(6) octahedra. Eight electrons are available for the formation of metal-metal bonds indicated by five relatively short Re-Re distances within the Re 4-rhombus, a "planar butterfly" type cluster. The theoretical calculations are indicating relatively low contribution of metal-metal bonding in the stability of the core. The stability of the +V-oxidation state, unusual for rhenium alkoxides can be at least partially attributed to the size effects in the packing of ligands. The X-ray powder study indicates that treatment of Re(4)O(4)(OEt)(12). in ambient atmosphere rapidly transforms it into a mixed-valence derivative Re(4)O(6)(OEt)(10) with a structure related to the earlier investigated cluster Re(4)O(6)(O(i)Pr)(10). Thermal decomposition of the latter rhenium oxoethoxide results in reduction to rhenium metal at as low temperatures as 380 degrees C, producing aggregates of metal nanoparticles with the average size of 3 nm.     

Generating the patterns of variation with GeoGebra: the case of polynomial approximations

In this paper, we report a teaching experiment regarding the theory of polynomial approximations at the university mathematics teaching in Sweden. The experiment was designed by applying Variation theory and by using the free dynamic mathematics software GeoGebra. The aim of this study was to investigate if the technology-assisted teaching of Taylor polynomials compared with traditional way of work at the university level can support the teaching and learning of mathematical concepts and ideas. An engineering student group (n = 19) was taught Taylor polynomials with the assistance of GeoGebra while a control group (n = 18) was taught in a traditional way. The data were gathered by video recording of the lectures, by doing a post-test concerning Taylor polynomials in both groups and by giving one question regarding Taylor polynomials at the final exam for the course in Real Analysis in one variable. In the analysis of the lectures, we found Variation theory combined with GeoGebra to be a potentially powerful tool for revealing some critical aspects of Taylor Polynomials. Furthermore, the research results indicated that applying Variation theory, when planning the technology-assisted teaching, supported and enriched students’ learning opportunities in the study group compared with the control group.     

Porous Silicon Carrier Matrices in Micro Enzyme Reactors-Influence of Matrix Depth

The influence of the carrier matrix depth was investigated for porous silicon enzyme reactors. For the experiments, <110> oriented silicon, p-type (20–70?Ω?cm), was used. Porous silicon was generated on planar surfaces and on anisotropically pre-etched high aspect-ratio parallel channel reactors. For each type of sample the porous silicon layer was generated for three depths, controlled by the anodisation time, and two current densities, to yield different morphologies. Glucose oxidase (GOx) was immobilised on the porous matrix by standard procedures for immobilisation of enzymes on silica. The enzyme activity of the samples was monitored by a colorimetric assay. The results clearly display the influence of the matrix depth for both the planar and the reactor structures. A 170-fold increase in catalytic turn-over, in comparison to an identical non-porous reference, was recorded for a reactor with an average pore depth of 10?μm. At depths above 10?μm the increase in catalytic efficiency levelled off. For the planar samples the levelling off occurred at an average pore depth of 20?μm.