International Portfolio Diversification: Short-Term Financial Assets and Gold

Using a continuous-time finance-theoretic framework, this paper presents the optimal portfolio rule of an international investor who consumes N national composite goods and who holds N domestic-currency-denominated assets with known nominal interest rates in an environment where prices of goods, assets and exchange rates follow geometric Brownian motion. It is shown that the currency portfolio rule described in Macedo (1982a) is applicable to the case where there are N assets with a known price and one asset, gold, with a random rice in terms of the numeraire. Under these assumptions, it is found that the optimal portfolio of an investor consuming goods from all major industrialized countries (according to their weight in total trade) would be dominated in March 1981 by long positions in U.S. dollars (25%), yen (17%), D. marks (16%), French francs (15%) and pounds sterling (10%). An investor consuming only U.S. goods, by contrast, would hold 96% of his optimal portfolio in U.S. dollars. Because of the covariance of exchange rates and gold, the exclusion of the latter generates substantial reshuffling. The analysis of the evolution of portfolios over time shows that shares changed dramatically at the beginning of the period and did not begin to approach their March 1981 values until the end of 1975. In the case of the yen and the pound there were oscillations throughout the period. With respect to the dollar share in the optimal portfolio of the U.S. and international investor, it is found that, in the period between late 1974 and mid-1976, a period in which the dollar is considered to have been "strong", a large decline in its optimal share took place.

Optimal Time-dependent Sequenced Route Queries in Road Networks

In this paper we present an algorithm for optimal processing of time-dependent sequenced route queries in road networks, i.e., given a road network where the travel time over an edge is time-dependent and a given ordered list of categories of interest, we find the fastest route between an origin and destination that passes through a sequence of points of interest belonging to each of the specified categories of interest. For instance, considering a city road network at a given departure time, one can find the fastest route between one's work and his/her home, passing through a bank, a supermarket and a restaurant, in this order. The main contribution of our work is the consideration of the time dependency of the network, a realistic characteristic of urban road networks, which has not been considered previously when addressing the optimal sequenced route query. Our approach uses the A* search paradigm that is equipped with an admissible heuristic function, thus guaranteed to yield the optimal solution, along with a pruning scheme for further reducing the search space. In order to compare our proposal we extended a previously proposed solution aimed at non-time dependent sequenced route queries, enabling it to deal with the time-dependency. Our experiments using real and synthetic data sets have shown our proposed solution to be up to two orders of magnitude faster than the temporally extended previous solution.Comment: 10 pages, 12 figures To be published as a short paper in the 23rd ACM SIGSPATIA

Electric and magnetic fields effects on the excitonic properties of elliptic core-multishell quantum wires

The effect of eccentricity distortions of core-multishell quantum wires on their electron, hole and exciton states is theoretically investigated. Within the effective mass approximation, the Schrodinger equation is numerically solved for electrons and holes in systems with single and double radial heterostructures, and the exciton binding energy is calculated by means of a variational approach. We show that the energy spectrum of a core-multishell heterostructure with eccentricity distortions, as well as its magnetic field dependence, are very sensitive to the direction of an externally applied electric field, an effect that can be used to identify the eccentricity of the system. For a double heterostructure, the eccentricities of the inner and outer shells play an important role on the excitonic binding energy, specially in the presence of external magnetic fields, and lead to drastic modifications in the oscillator strength.Comment: 17 pages, 10 figure

Hybrid GMR Sensor Detecting 950 pT/sqrt(Hz) at 1 Hz and Room Temperature.

Advances in the magnetic sensing technology have been driven by the increasing demand for the capability of measuring ultrasensitive magnetic fields. Among other emerging applications, the detection of magnetic fields in the picotesla range is crucial for biomedical applications. In this work Picosense reports a millimeter-scale, low-power hybrid magnetoresistive-piezoelectric magnetometer with subnanotesla sensitivity at low frequency. Through an innovative noise-cancelation mechanism, the 1/f noise in the MR sensors is surpassed by the mechanical modulation of the external magnetic fields in the high frequency regime. A modulation efficiency of 13% was obtained enabling a final device's sensitivity of ~950 pT/Hz1/2 at 1 Hz. This hybrid device proved to be capable of measuring biomagnetic signals generated in the heart in an unshielded environment. This result paves the way for the development of a portable, contactless, low-cost and low-power magnetocardiography device

Sol-gel electrochromic device

All solid state electrochromic devices have potential applications in architectural and automotive fields to regulate the transmission and reflection of radiant energy. We present the optical and electrochemical characteristics of two solid state windows having the configuration glass/ITO/TiO2-CeO2/TiO2/TiO2-CeO2/ITO/glass and glass/ITO/WOa/TiO2/TiO2-CeO2/ITO/glass where the three internal layers have been prepared by sol gel methods. The preparation of the individual sols and some physical properties of the different sol gel coatings are reported

An association UNIFAC model for aqueous and alcohol solutions of sugars

In this work, a modified UNIFAC model [1] that explicitly takes into account association effects is applied to mixtures containing common sugars, alcohols and water. Following the same strategy adopted before [2], four residual groups were defined to represent the sugars family: the pyranose ring (PYR), the furanose ring (FUR), the osidic bond (-O-) and the hydroxyl ring group (OH ring) [2]. For the association term, a general two sites OH associating group is used to represent association effects in these solutions, allowing a straightforward extension to multicomponent mixtures. Correlation of both solvent activity properties (water activities, vapour pressures, boiling and freezing points of aqueous D-glucose and D-fructose solutions) and sugars (D-fructose, D-glucose and sucrose) solubility in water, ethanol and methanol give very good results. Satisfactory predictions are obtained for vapour-liquid equilibrium and solid-liquid equilibrium of ternary and quaternary mixtures of sugars in mixed solvents