Alimentación y salud 2006: un laberinto cultural y científico

Al laberinto de la alimentación y la salud se accede por cuatro puertas: la tradición; las dietas regionalistas (mediterránea, Atlántida, de la dehesa); las dietas evolucionistas o paleodietas y la puerta del futuro: los alimentos funcionales, la nutraceútica y la nutrigenómica. En este trabajo se describen las características de estas cuatro alternativas.Elikadura eta osasunaren labirintora lau ateotatik iristen da: tradizioa; eskualdeko dietak (Mediterraneokoa, Atlantidakoa, larrekoa); dieta eboluzionistak edo paleodietak, eta etorkizunaren atea: janari funtzionalak, nutrazeutika eta nutrigenomika. Lan honetan lau aukera horien ezaugarriak deskribatzen dira.On accède au labyrinthe de l'alimentation et de la santé par quatre portes : la tradition ; les régimes régionalistes (méditerranéen, Atlantide, de la «dehesa» (pâturage) ; les régimes évolutionnistes ou paléo régimes et la porte du futur: les aliments fonctionnels, la nutraceutique et la nutrigénomique. On décrit dans ce travail les caractéristiques de ces quatre alternatives.The labyrinth of nutrition and health can be accessed via four doors: tradition; regional diets (Mediterranean, Atlantic, Extremadura); evolutionist diets orpaleodiets and the door to the future: functional foods, nutraceutics andnutrigenomics. This paper describes the characteristics of these four alternatives

Large-signal dynamics of an ultrafast semiconductor laser at digital modulation rates approaching 10 Gbit/s

High-fidelity pseudorandom digital modulation at 8.2 Gbit/s of an ultrahigh speed semiconductor laser is demonstrated. Studies using simple but representative pulse patterns at 10 Gbit/s give insights into the maximum digital modulation rate attainable from a given laser, as well as relations between large-signal digital performance and small-signal analog response

Intermodulation distortion in a directly modulated semiconductor injection laser

A most important quantity in high-frequency analog transmission is the intermodulation distortion product. Experimental studies of the third order intermodulation distortion products in the modulation response of high-speed semiconductor lasers give very low values (< −60 dB) at low frequencies, an increase at a rate of 40 dB/dec as the modulation frequency is increased, and a leveling off at one-half of the relaxation oscillation resonance frequency. These experimental results can be well explained by a theory based on a perturbative analysis of laser dynamics

A theory of longitudinal modes in semiconductor lasers

A theory of longitudinal mode lasing spectrum of semiconductor lasers is developed which takes into account the nonuniform carrier and photon distributions and local gain spectrum shifts inside lasers with low end mirror reflectivities. The theory gives results consistent with observed longitudinal mode behavior in lasers with reduced facet reflectivity

Self-sustained picosecond pulse generation in a GaAlAs laser at an electrically tunable repetition rate by optoelectronic feedback

We demonstrate that applying optoelectronic feedback to a high-speed, self-pulsing semiconductor laser is an effective and practical means of generating picosecond optical pulses (~10–20 ps) at a very high repetition rate, between 1 to 5 GHz, which can be electrically tuned. The optical pulses are very stable both on a short term basis with a frequency stability of one part in 10^5, and on the long term basis as a result of the absence of critical optical alignment. This laser system is potentially very useful in high-speed electro-optic signal processing, optical multiplexing, or laser ranging

Importance of mutual benefits in online knowledge sharing communities

The sustainability of knowledge sharing e-communities is a major issue at present. A hypothesis was proposed at the outset in the paper that the provision of mutual benefits among participants will lead to positive participation. Drawing from the economic and social theories, a framework for analysis was developed and tested in an empirical study. The preliminary results demonstrated a direct relationship between mutual benefits and the level of participation, and hence supported the hypothesis