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Chickens have been selected for millenniums on their ability to select food in complex and variable environments. Artificial selection for juvenile body weight using a single balanced food might have modified the ability of chickens to adapt to a choice feeding situation (Siegel and Dunnington, 1990). However, diet selection for protein has been demonstrated in many recently published experiments (for review: Forbes and Shariatmadari, 1994).
Broiler chickens have been selected for increased growth rate and adapted to consumer demands. A range of commercial products is being developed from slower growing country-type meat chickens (named ‘Label’ in France) as well as from faster growing broilers with a high yield of breast meat. Nutritionists have to satisfy a need for feeding programmes adapted to meet the demands for various end-products. Selection for growth rate has to be shown to change the food intake behaviour of chickens (i.e. Barbato et al., 1980). Emmans (1991) demonstrated that chickens are able to adjust their food choices if the paradigm permits an adequate choice. In a series of experiments (see Picard et al., 1994 for review) the authors concluded that ‘high producing animals are not necessarily those that will react most clearly to an amino acid deficiency by altering their food intake and/or their feeding behavior’.
Selection for meat production in poultry includes commercial development of meat-type chickens, turkeys and waterfowl and laboratory studies that involve these types of poultry. Heritabilities for growth traits are moderate to high, enabling response to selection for these traits. Changes in growth traits result in correlated responses in feed intake and have a negative relationship with reproductive traits. That is, deviations from intermediate growth rates are deleterious to reproduction. In this paper we discuss genetic aspects of poultry meat production and long-term laboratory selection experiments for growth. Emphasis is given to the species with the most extensive research base, the chicken.
Nanocrystalline gold films were prepared by advanced gas deposition. Electric field induced effects on the film structure during and after deposition was investigated. A dc electric field in the range 2 ≤Ua ≤ 8 V/cm, was applied parallel to the substrate surface and led to changes of film microstructure and resistivity. In another set of experiments, films deposited at Ua = 0 were exposed to electric fields of similar strength after deposition. Film degradation could be understood from a mechanism consistent with a biased-percolation effect. Our results show that it is possible to control the film structure by varying the strength of an applied electric field.
LiNbO3 is the best substrate for modulators and switches for integrated optics. Efficient low loss waveguides for light in LiNbO3 are formed by introducing Ti-ions into its lattice, thus increasing locally the ordinary and the extraordinary indices of refraction. We are the first to use the very versatile technique of ion-implantation to administer Ti into LiNbO3. This implantation process offers the possibility to introduce significantly more Ti into a well-defined volume than conventional diffusion techniques. During this process first an amorphous non-equilibrium phase is generated, which has to be kept at low temperatures in order to prevent segregation. Subsequent thermal treatment leads to solid phase epitaxy and restores the desired stable crystalline state. We have used this technique to fabricate excellent planar waveguides, channel waveguides and Mach-Zehnder modulators.
The THz spectral region includes a number of important transitions which
allow us to trace the evolution of the interstellar medium. Because of the
opacity of the atmosphere in this spectral range, the best sites for
ground-based THz observations are on the Antarctic Plateau; of these sites,
Dome A is expected to be the best. THz survey science can be carried out
with small telescopes, easing logistical constraints. By deploying a
submillimetre-wave tipper/ telescope to Dome A, we have trialled several
technologies for such an instrument, and we are able to test whether the
site quality is sufficient for THz surveys.
The Telemedicine Spacebridge, a satellite-mediated, audio-video-fax link between four United States and two Armenian and Russian medical centers, permitted remote American consultants to assist Armenian and Russian physicians in the management of medical problems following the December 1988 earthquake in Armenia and the June 1989 gas explosion near Ufa.
During 12 weeks of operations, 247 Armenian and Russian and 175 American medical professionals participated in 34 half-day clinical conferences. A total of 209 patients were discussed, requiring expertise in 20 specialty areas.
Telemedicine consultations resulted in altered diagnoses for 54, new diagnostic studies for 70, altered diagnostic processes for 47 and modified treatment plans for 47 of 185 Armenian patients presented. Simultaneous participation of several US medical centers was judged beneficial; quality of data transmission was judged excellent.
These results suggest that interactive consultation by remote specialists can provide valuable assistance to on-site physicians and favorably influence clinical decisions in the aftermath of major disasters.