RESUMO
We directly measure the low energy excitation modes of the quantum Ising magnet LiHoF_{4} using microwave spectroscopy. Instead of a single electronic mode, we find a set of collective electronuclear modes, in which the spin-1/2 Ising electronic spins hybridize with the bath of spin-7/2 Ho nuclear spins. The lowest-lying electronuclear mode softens at the approach to the quantum critical point, even in the presence of disorder. This softening is rapidly quenched by a longitudinal magnetic field. Similar electronuclear structures should exist in other spin-based quantum Ising systems.
RESUMO
Five competitive cyclists were used to determine the effects of fluid intake (16 ml.kg-1) consisting of: (i) non-nutrient control (CON); (ii) fructose (1 g.kg-1) before exercise (FRU); (iii) caffeine (5 mg.kg-1) before exercise (CAF); (iv) glucose (1 g.kg-1) during exercise (GLU); and (v) fructose/caffeine before and glucose during exercise (CFG) on blood glucose, free fatty acids, muscle glycogen, and other parameters. Exercise consisted of 90 min of cycling at 65 to 70% VO2max. Following exercise, blood glucose was found to be significantly (P less than 0.05) higher for CFG and GLU (117 and 109 mg%) compared to CON, CAF, and FRU (92, 89, and 86 mg%). Blood free fatty acids rose (P less than 0.05) further for CON (1,336), CAF (1,126), and FRU (1,034) over CFG (737) and GLU (714 mumol.l-1). Muscle glycogen utilization was greater (P less than 0.05) for CON (91) vs CAF (63) and GLU (62 mumol/g-1 wet muscle weight). It was concluded that GLU and CAF decrease muscle glycogen utilization, FRU is likely to cause gastric upset, and ingestion of multiple substances produces the greatest variability in muscle glycogen utilization and may provide added endurance benefits in some individuals.
Assuntos
Cafeína/farmacologia , Frutose/farmacologia , Glucose/farmacologia , Glicogênio/metabolismo , Músculos/metabolismo , Esforço Físico , Adulto , Feminino , Humanos , Masculino , Resistência FísicaRESUMO
Sixteen mixed age Angora does were synchronised by progesterone injections and superovulated with either PMSG or FSH in 1982 and six synchronised Angora and seven Saanens were superovulated with FSH in 1983. All donors entire mated and were subjected to egg recovery by a uterine flush conducted during surgery about five days after oestrus. The mean ovulation rate and number of transferable embryos recovered from Angoras treated with PMSG in 1982 was 9.1 and 5.1, respectively, and for FSH treated donors was 15.1 and 11.0. Results for Angoras treated in 1983 were 5.3 and 5.0 and for Saanens were 29.3 and 25.3. Each year recipient feral and Angora does were synchronised, and 329 embryos were transferred surgically to 151 recipients. One hundred and sixteen (77%) of the recipients kidded producing 191 kids (58% embryo survival). Well fed Angora and Saanen donors superovulated with FSH produced 8 and 17 offspring, respectively, in the year of surgery. This rate of reproduction is about 8 times faster than normal and about double that achieved when donors are superovulateb with PMSG.
RESUMO
Thirty-five mixed-age Angora does were subjected to superovulation and oestrous synchronization and of the 34 which were subsequently entire mated, 33 were subjected to surgical egg recovery approximately five days after oestrus. These 33 donors averaged 8.8 ovulations and 2.5 large (>5 mm) follicles. All corpora lutea in six donors were undergoing premature regression. The average donor egg recovery rate, egg fertilization rate and percent of eggs transferable was 82,87 and 81%, respectively, giving 6.8 eggs, 6.0 embryos and 5.5 transferable embryos per donor. Egg recovery was reduced dramatically when premature regressing corpora lutea were present. Recipient feral does were synchronized and 183 embryos transferred surgically to 133 recipients. Eighty-eight (66%) of the recipients kidded producing 118 kids (64% embryo survival). The 35 potential donors produced 36 kids from their natural mating which occurred shortly after surgery. Thus the donors produced a total of 154 kids from embryo transfer and natural mating, an average of 4.4 kids/doe/breeding season. This rate of reproduction is four to five times faster than normal and confirms that the technique achieves its objective of rapidly increasing the number of offspring from selected animals.