Fusion systems and amalgams

We study reduced fusion systems from the point of view of their essential subgroups, using the classification by Goldschmidt and Fan of amalgams of prime index to analyze certain pairs of such subgroups. Our results are applied here to study reduced fusion systems over $2$ -groups of order at most 64, and also reduced fusion systems over $2$ -groups having abelian subgroups of index two. More applications are given in later papers.     

Quantized transport in two-dimensional spin-ordered structures

We study in detail the transport properties of a model of conducting electrons in the presence of double exchange between localized spins arranged on a 2D Kagome lattice, as introduced by Ohgushi, Murakami and Nagaosa. The relationship between the canting angle of the spin texture θ and the Berry phase field flux per triangular plaquette φ is derived explicitly and we emphasize the similarities between this model and Haldane's honeycomb lattice version of the quantum Hall effect. The quantization of the transverse (Hall) conductivity σ _xy is derived explicitly from the Kubo formula and a direct calculation of the longitudinal conductivity σ _xx shows the existence of a metal–insulator transition as a function of the canting angle θ (or flux density φ). This transition might be linked to that observable in the manganite compounds or in the pyrochlore ones, as the spin ordering changes from ferromagnetic to canted.     

Radiative coupling of high-order plasmonic modes with far-field

In the last few years, hybrid systems consisting of punctual sources and metallic nanostructures have been assembled and studied. Furthermore, the radiative coupling between the two counterparts has become a crucial aspect to be explored in nanophotonics and plasmonics. In this paper a numerical framework based on the Discrete Dipole Approximation is presented as a simple computational scheme to analyze the decay dynamics of an emitter when it is located in the near proximities of metallic nanoparticles. This approach allows to go beyond the analytically solved cases and to predict the optical response of more complex shaped nanoparticles. Here the excitation of dipole and higher-order modes is studied as a function of the applied radiation with a particular attention paid to the changes induced in the response by approaching the source to the metal. Numerical results, obtained for Ag spheroids and conically shaped nanoparticles, are explained by analyzing the charge density induced on the surface of the nanoparticles, this allowing to distinguish dark from radiative modes in a straightforward way.     

Lattice location of light implanted ions in Si and Ge after laser annealing

Abstract

Radiation damage produced by short ranged (ranges 20–30 μm) charged particles (alpha particles and fission fragments) in thick plastic track detectors (thickness ≈ 150 μm) has been enlarged to produce “through” holes by using a combination of electrochemical and chemical etching processes. A series of experiments were conducted with a view to optimize the operating conditions required to produce through holes with most suitable profiles for a particular application at hand. This novel technique has been employed in producing thick nuclear track filters using fission fragments from U-235 fission and alpha particles from radon and its daughters.     

Fundamental and technological aspects of glass studied by nuclear techniques

Abstract

Nuclear techniques (Rutherford back-scattering and nuclear reactions) appear very useful in the near surface analysis of glass. These techniques offer a non-destructive method of analysis, with high depth resolution without radiation effects induced by the ion beam.

In this paper we present some experimental results concerning the analysis of glass surfaces obtained by different treatments. Initially the water vapour attack kinetics was investigated with the ²³Na(ρ, α)²⁰Ne nuclear reaction. Measurements were performed on three different flat glasses obtained by different industrial processes.

Another aspect of particular importance from both scientific and applied viewpoints is the kinetics of the surface reaction and diffusion processes occurring in silicate glasses. In particular the Na⁺?K⁺ interdiffusion has been investigated with the RBS technique at different temperatures in aluminosilicate and borosilicate glasses.

Finally, a technological aspect of great interest is connected to the optical properties modification when glasses are covered with different types of coatings. RBS analysis allows helpful information about elemental composition of the coatings and their depth distribution. In many cases it is possible to obtain the stoichiometric composition and the thickness when atomic density is known.     

Liquidity and credit risk

The paper uses fuzzy measure theory to represent liquidity risk, i.e. the case in which the probability measure used to price contingent claims is not known precisely. This theory enables one to account for different values of long and short positions. Liquidity risk is introduced by representing the upper and lower bound of the price of the contingent claim computed as the upper and lower Choquet integral with respect to a subadditive function. The use of a specific class of fuzzy measures, known as g λ measures enables one to easily extend the available asset pricing models to the case of illiquid markets. As the technique is particularly useful in corporate claims evaluation, a fuzzified version of Merton's model of credit risk is presented. Sensitivity analysis shows that both the level and the range (the difference between upper and lower bounds) of credit spreads are positively related to the ‘quasi debt to firm value ratio’ and to the volatility of the firm value. This finding may be read as correlation between credit risk and liquidity risk, a result which is particularly useful in concrete risk-management applications. The model is calibrated on investment grade credit spreads, and it is shown that this approach is able to reconcile the observed credit spreads with risk premia consistent with observed default rate. Default probability ranges, rather than point estimates, seem to play a major role in the determination of credit spreads.     

Dynamic magnetic resonance microscopy of flour dough fermentation

Magnetic resonance microscopy was carried out at 9.4 T with a voxel volume of 117 x 117 x 500 microm(3) and temporal resolution was adjusted to 8.5 min for a dynamic follow-up of bread dough fermentation during 2 h at a constant temperature of 30 degrees C. An image analysis procedure based on gray levels mathematical morphology routines was performed to assess bubble distribution and cell wall thickness inside the imaged bread dough. The evolution of the extracted curves allows one to characterize quantitatively the amount of bubbles and their growth. Using this procedure, different bread doughs were examined to determine the impact of dough composition on the structure modification during fermentation.     

Sparse Dynamic Programming for Longest Common Subsequence from Fragments

Sparse Dynamic Programming has emerged as an essential tool for the design of efficient algorithms for optimization problems coming from such diverse areas as computer science, computational biology, and speech recognition. We provide a new sparse dynamic programming technique that extends the Hunt–Szymanski paradigm for the computation of the longest common subsequence (LCS) and apply it to solve the LCS from Fragments problem: given a pair of strings X and Y (of length n and m, respectively) and a set M of matching substrings of X and Y, find the longest common subsequence based only on the symbol correspondences induced by the substrings. This problem arises in an application to analysis of software systems. Our algorithm solves the problem in O(|M| log |M|) time using balanced trees, or O(|M| log log min(|M|, nm/|M|)) time using Johnson's version of Flat Trees. These bounds apply for two cost measures. The algorithm can also be adapted to finding the usual LCS in O((m + n) log |Σ| + |M| log |M|) time using balanced trees or O((m + n) log |Σ| + |M| log log min (|M|, nm/|M|)) time using Johnson's version of Flat Trees, where M is the set of maximal matches between substrings of X and Y and Σ is the alphabet. These bounds improve on those of the original Hunt–Szymanski algorithm while retaining the overall approach.     

Extremal Betti Numbers of Some Cohen-Macaulay Binomial Edge Ideals

We provide the regularity and the Cohen-Macaulay type of binomial edge ideals of Cohen-Macaulay cones,and we show the extremal Betti numbers of some classes of Cohen-Macaulay binomial edge ideals:Cohen-Macaulay bipartite and fan graphs.In addition,we compute the Hilbert-Poincaré series of the binomial edge ideals of some Cohen-Macaulay bipartite graphs.