The relatively random spiking times of individual neurons provide a source of noise in the brain. We show how this noise interacting with altered depth in the basins of attraction of networks involved in short-term memory, attention, and episodic memory provide an approach to understanding some of the cognitive changes in normal aging. The effects of the neurobiological changes in aging that ar...

expansive soils show swelling and shrinkage behavior when subjected to cyclic wetting and drying. the variation in water content influence the volume change in this kind of soil. these volume changes can cause ground movement which may result in damage to the buildings and structures. to study the behavior, a number of successive wetting-drying cycles were conducted on a statically compacted ex...

background: mesenchymal stem cells (mscs) can be expanded and differentiated into many mature cell types including smooth muscle cells (smcs). in addition to growth factor, cyclic stretch contributes to differentiation of stem cells. mechanical stimuli are critical to morphological changes, development, regeneration, differentiation and pathology of mesenchymal tissues. the aim of this study is...

was found, but only after five and 10 days of treatment was the increase statistically significant when compared with basal levels. Similar changes were observed for guanosine 3':5'-phosphate (cyclic GMP), but percentage increases were higher than for cyclic AMP. Initial diarrhoea disappeared spontaneously, and at 15 days the levels of both cyclic nucleotides were not significantly different fr...

Melatonin production in the pineal gland is high at night and low during the day. This rhythm reflects circadian changes in the activity of serotonin N-acetyltransferase [arylalkylamine N-acetyltransferase (AA-NAT); EC 2.3.1.87], the penultimate enzyme in melatonin synthesis. The rhythm is generated by an endogenous circadian clock. In the chick, a clock is located in the pinealocyte, which als...

Cytochalasin B (CB) shows a marked concentration-dependent inhibition of the incorporation of [(3)H]thymidine into Chinese hamster ovary cells. This inhibition was shown to result from an inhibition of thymidine uptake, not from an inhibition of DNA synthesis. Cells normally acquire the capacity to transport thymidine as they move from the G1 stage of the cell cycle into the S phase. If CB is a...

K N O W L E D G E of the normal quantitative cyclic changes in the ovarian follicular system would be a meaningful aid in assessing the influence of exogenous agents on the ovary. Previous reports on cyclic changes in bovine vesicular follicles (Hammond, 1927: Cole, 1930; McNutt , 1927: Cupps et al., 19,59; Hansel, 1959) were based on gross counts, or study of the largest follicle in isolated s...