Tracking error: a multistage portfolio model

We study multistage tracking error problems. Different tracking error measures, commonly used in static models, are discussed as well as some problems which arise when we move from static to dynamic models. We are interested in dynamically replicating a benchmark using only a small subset of assets, considering transaction costs due to rebalancing and introducing a liquidity component in the portfolio. We formulate and solve a multistage tracking error model in a stochastic programming framework. We numerically test our model by dynamically replicating the MSCI Euro index. We consider an increasing number of scenarios and assets and show the superior performance of the dynamically optimized tracking portfolio over static strategies.     

Fractal fluctuations and quantum-like chaos in the brain by analysis of variability of brain waves: A new method based on a fractal variance function and random matrix theory: A link with El Naschie fractal Cantorian space–time and V. Weiss and H. Weiss golden ratio in brain

We develop a new method for analysis of fundamental brain waves as recorded by the EEG. To this purpose we introduce a Fractal Variance Function that is based on the calculation of the variogram. The method is completed by using Random Matrix Theory. Some examples are given. We also discuss the link of such formulation with H. Weiss and V. Weiss golden ratio found in the brain, and with El Naschie fractal Cantorian space–time theory.     

Glassy Carbon Electrodes Film‐Modified with Acidic Functionalities. A Review

This review addresses recent advances in the field of glassy carbon electrodes film‐modified by acidic functionalities. Attention was posed at the architecture of the functionalizing surface film and at practical applications of the relevant sensors. To facilitate the reading, some summarizing tables were included, each one regarding a certain type of surface modification. A final section is aimed at detailing some remarks emerging from the analysis of the reviewed matter. This allowed highlighting the potentialities of the examined sensors, and evidencing some criticisms about how some of their performances were presented in the relevant papers.     

Equivalent detector models for the simulation of efficiency response of an HPGe detector with PENELOPE code

ABSTRACT

In this work, some ‘equivalent’ models for the simulation of efficiency response of a High-Purity Germanium (HPGe) detector, installed inside a ‘low background’ bunker in the Engineering Department of the University of Palermo, were developed. The main feature was to attribute the uncertainties of the model to only one of the parameters, the dead layer of the detector, keeping unchanged the other data provided by the manufacturer. With this technique, using the Monte Carlo PENELOPE code in the 2011 version, the efficiency response was evaluated and compared with the previous one performed with MCNP5 code.

The validation of equivalent models is performed by comparing the simulation results with that of experimental spectrometric measurements of calibrated point sources and characterized volumetric sources such as a Marinelli beaker and an air filter reduced to a ‘packet-sample’.

The use of equivalent models makes the evaluation of efficiency curves with a Monte Carlo code easier and faster, and requires only a few experimental values for validation.     

Determination of boron in silicon-doped gallium arsenide by electrothermal atomic absorption spectrometry and ultraviolet-visible spectrophotometry

Two methods have been developed for the determination of boron impurities in silicon-doped gallium arsenide (GaAs) for electronics. The first method employs the electrothermal atomic absorption spectrometry (ETAAS), the second, the UV-Vis molecular absorption spectrophotomety. In both cases the GaAs sample is decomposed with aqua regia (1+1). To prevent Ga(III) interference on the ETAAS determination of boron, a double extraction of the chlorogallic acid (HGaCl4) in diethyl ether is performed. To improve the overall ETAAS performance, the graphite tubes were pre-treated with iridium(III) and tungsten(IV). A mixed chemical modifier containing Ni(II), Sr(II) and citric acid was also used. The characteristic mass (m0) is 301 +/- 47 pg and the detection limit (3sB) is 2.4 microg g(-1). The classic UV-Vis spectrophotometric procedure using curcumin was also extended to the determination of boron in GaAs. By masking Ga(III) with EDTA and a preliminary extraction of boron with 2-ethyl-hexane 1,3-diol, performed on a semi-micro scale, a detection limit of 0.6 microg g(-1) was achieved. Both methods were applied to the analysis of two Si-doped GaAs samples which were suspected of being boron-contaminated. Results are compared with those obtained by direct analysis of the decomposed sample solution using the inductively coupled plasma atomic emission spectrometry (ICP-AES).     

Volatility versus downside risk: performance protection in dynamic portfolio strategies

Computational Management Science - Volatility-based and volatility targeting approaches have become popular among equity fund managers after the introduction in 1993 of the VIX, the implied...     

Silica Supported Chromium Catalyst. Reactivity Studies with Alcohols

Reaction rates of primary and secondary alcohols over chromium on silica catalysts prepared by the ion exchange method, in the presence and absence of oxygen, were measured. The effect of temperature and feed composition on activity and selectivity has been examined.