We report experimental evidence of the existence of two variants of the E'
gamma centers induced in silica by gamma rays at room temperature. The two
variants are distinguishable by the fine features ...of their line shapes in
paramagnetic resonance spectra. These features suggest that the two E' gamma
differ for their topology. We find a thermally induced interconversion between
the centers with an activation energy of about 34 meV. Hints are also found for
the existence of a structural configuration of minimum energy and of a
metastable state.
We study experimentally the dynamical and decay properties of the Stimulated
Nutation Echo (SNE) in a two-level spin system. This is the signal which
appears in the transient response of the system ...to the second pulse at time
tau_1 elapsed from its beginning and coinciding with the duration of the first
pulse. The information about the first pulse duration is imprinted into the
population difference of the inhomogeneously broadened ensemble of the
two-level absorbers. The decay of the SNE signal has two contributions. One
originates from the population decay during the time tau between the pulses.
Another is caused by the coherence loss during the excitation by the first
pulse and the reading time of the second pulse. Experimental results on the
decay properties induced by these mechanisms are presented. The dependence of
these decay rates on the pulse intensity is discussed, and its relationship
with the anomalous (non-Bloch) decay of other coherent transients in solids is
examined.
We study experimentally the dynamical and decay properties of the Stimulated Nutation Echo (SNE) in a two-level spin system. This is the signal which appears in the transient response of the system ...to the second pulse at time tau_1 elapsed from its beginning and coinciding with the duration of the first pulse. The information about the first pulse duration is imprinted into the population difference of the inhomogeneously broadened ensemble of the two-level absorbers. The decay of the SNE signal has two contributions. One originates from the population decay during the time tau between the pulses. Another is caused by the coherence loss during the excitation by the first pulse and the reading time of the second pulse. Experimental results on the decay properties induced by these mechanisms are presented. The dependence of these decay rates on the pulse intensity is discussed, and its relationship with the anomalous (non-Bloch) decay of other coherent transients in solids is examined.
We report experimental evidence of the existence of two variants of the E' gamma centers induced in silica by gamma rays at room temperature. The two variants are distinguishable by the fine features ...of their line shapes in paramagnetic resonance spectra. These features suggest that the two E' gamma differ for their topology. We find a thermally induced interconversion between the centers with an activation energy of about 34 meV. Hints are also found for the existence of a structural configuration of minimum energy and of a metastable state.
Three- to six-day-old lambs infused with 100 mU ⋅ kg
⋅ min
insulin required greater amounts of glucose to maintain euglycemia during a euglycemic hyperinsulinemic clamp compared with 31- to ...35-day-old insulin-infused lambs (15.87 ± 3.47 vs. 4.30 ± 1.11 mg ⋅ kg
⋅ min
, P < 0.05, respectively). Endogenous glucose production persisted in both groups; however, the percent decrease compared with age-matched lambs receiving no insulin was greater in the younger group compared with the older group (53%, P < 0.001, vs. 34%, P < 0.01). The younger animals showed greater glucose utilization compared with the older animals (215 vs. 96%, respectively, P < 0.01). No effect of insulin was noted on GLUT-4 protein expression in either group. GLUT-2 expression was increased in older vs. younger lambs. Older insulin-infused lambs showed lower GLUT-2 expression than older 0 insulin-infused lambs 0.94 ± 0.07 vs. 1.64 ± 0.10 (OD) units, P < 0.005. Increased sensitivity to insulin in the younger animals was not related to acute changes in GLUT-4 expression. Increased GLUT-2 expression with age, as well as decreased expression with hyperinsulinemia, is consistent with the development of an insulin-resistant state in the adult.
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