Vertical link solutions for multilayer optical-networks-on-chip topologies

This paper presents two different approaches that may allow the optical interconnection between superposed levels of multilayer photonic circuits as, for example, in optical-networks-on-chip. The first configuration is based on multi-mode interference devices, while the second one exploits multiple stacked directional couplers. The issues concerning the analytical and numerical design of such devices are discussed, together with a performance analysis in terms of efficiency and footprint.     

Non-Thermal Effects of Microwave Oven Heating on Ground Beef Meat Studied in the Mid-Infrared Region by Fourier Transform Infrared Spectroscopy

The effects of cooking by microwave oven on the secondary structure of lipid and protein contents in bovine ground beef were investigated in the midinfrared region by Fourier transform infrared (FTIR) spectroscopy to highlight the nonthermal effects of microwave oven heating. Samples of bovine ground beef were cooked in a conventional electric oven at the temperature of 175°C for 15 min and in a microwave oven at 800 W for 1½ min. Spectra analyses of bovine meat after cooking in the conventional oven evidenced a relevant increase in intensity of the carbonyl band at 1742 cm^?1 and of the methylene group at 2921 and 2853 cm^?1 that can be attributed to the Maillard reaction. In contrast, the increase in intensity of these bands after microwave oven heating was less than that which occurred after conventional cooking, showing that the temperature in ground beef meat samples during microwave heating was less than that induced by conventional heating. Spectral analysis in the amide I, II, and III regions showed that a significant increase in intensity occurred in the region from 1660 to 1675 cm^?1 and around 1695, 1635, 1575, and 988 cm^?1 after cooking by means of a microwave oven. These features, which can be attributed to β-turns and β-sheet structures, are characteristic of disorder processes in meat protein contents and increasing transition dipole coupling due to higher contents in aggregated β-sheet structures. This result highlighted nonthermal effects of microwave oven heating in the protein's secondary structure.     

Some probabilistic techniques in field theory

We study, in the context of the Markov hyerarchical fields (d=2, 3) the role of the Markov property, of formal renormalization and of formal positivity. We determine upper and lower bounds for the ground state energy and discuss their relation with the perturbation theory series.This work has been partially supported by I.N.F.N., G.N.F.M., and G.N.S.M.     

Stochastic analysis in life office management: applications to large annuity portfolios

The paper deals with the riskiness analysis for a large portfolio of life annuities. By means of the limiting distribution of the present value of the portfolio, in the first part of the paper a model for evaluating the investment and the projection risks is presented. In the second part, with regard to the investment risk's effects, the insolvency risk is measured considering the cumulative probability distribution function of the discounted average cost per policy. Copyright © 2003 John Wiley & Sons, Ltd.     

Renormalization theory in four dimensional scalar fields (II)

We interpret the results of the preceding paper (I) in terms of partial resummations of the perturbative series for the effective interaction. As an application we sketch how our resummation method leads to a simple summation rule leading to a convergent expansion for the Schwinger functions of the planar ₄ ⁴ -theory.     

Sequential stopping rules for the multistart algorithm in global optimisation

In this paper a sequential stopping rule is developed for the Multistart algorithm. A statistical model for the values of the observed local maxima of an objective function is introduced in the framework of Bayesian non-parametric statistics. A suitablea-priori distribution is proposed which is general enough and which leads to computationally manageable expressions for thea-posteriori distribution. Sequential stopping rules of thek-step look-ahead kind are then explicitly derived, and their numerical effectiveness compared.     

Spin-flip limited exciton dephasing in CdSe/ZnS colloidal quantum dots

The dephasing time of the lowest bright exciton in CdSe/ZnS wurtzite quantum dots is measured from 5 to 170 K and compared with density dynamics within the exciton fine structure using a sensitive three-beam four-wave-mixing technique unaffected by spectral diffusion. Pure dephasing via acoustic phonons dominates the initial dynamics, followed by an exponential zero-phonon line dephasing of 109 ps at 5 K, much faster than the ~10 ns exciton radiative lifetime. The zero-phonon line dephasing is explained by phonon-assisted spin flip from the lowest bright state to dark-exciton states. This is confirmed by the temperature dependence of the exciton lifetime and by direct measurements of the bright-dark-exciton relaxation. Our results give an unambiguous evidence of the physical origin of the exciton dephasing in these nanocrystals.     

Fourier Self-Deconvolution Analysis of β-Sheet Contents in the Amide I Region of Hemoglobin Aqueous Solutions under Exposure to 900 MHz Microwaves and Bioprotective Effectiveness of Sugar and Salt Solutions

Spectroscopic Fourier self-deconvolution analysis was used to investigate β-sheet features in the secondary structure of hemoglobin under mobile phone microwaves at 900 MHz. To this end, four samples of hemoglobin in bidistilled water, sucrose, trehalose, and sodium chloride aqueous solutions were exposed for up to 4 hr to 900 MHz microwaves at an average H-field intensity of 42 mA/m. Quantitative spectral analyses highlighted significant increases in β-sheet contents in the Amide I region of hemoglobin samples in bidistilled water solution, but no appreciable change was observed in hemoglobin samples in sucrose, trehalose, and sodium chloride solutions. These results led us to conclude that mobile phone microwaves can denaturate hemoglobin in bidistilled water solution whereas sucrose, trehalose, and sodium chloride solutions produce a protective effect against microwaves, preserving the protein from unfolding.     

Double Vivaldi antenna for wireless optical networks on chip

In this paper we present a double plasmonic Vivaldi antenna for on-chip optical wireless communication. The proposed antenna is a two-element broadside array fed by a silicon waveguide. The designs of the power splitter and of the hybrid Si-plasmonic coupler used for antenna excitation are described in detail. The array radiation characteristics are optimized through Finite Difference Time Domain simulations and the performance of a point-to-point link is evaluated. The proposed double Vivaldi array increases the gain of 3 dB with respect to a single antenna, improving the received power on a link of 6 dB when the double antenna is used for both transmitting and receiving sections.