Powerful Modulatory Effects Research Articles

The effects of channel separation, input power and cross-phase modulation on nonlinear WDM systems with dispersion compensation

This paper analyzes the effects of channel separation, cross-phase modulation and input power on nonlinear WDM systems with conventional single-mode fiber combined with dispersion-compensating fiber. The conclusions are: (i) The performance of different signal channels depends on the input power and the channel separation. (ii) In general, the shorter the channel separation, the shorter the maximum transmission distance; the larger the input power, the shorter the maximum transmission distance. (iii) Cross-phase modulation plays an important role on the performance of nonlinear WDM with DCF compensation.

The prevention or treatment of age‐related osteoporosis in the elderly by systemic recombinant growth factor therapy (rhIGF‐I or rhTGFβ): a perspective

Both insulin-like growth factor-I (IGF-I) and transforming growth factor beta (TGF beta) have powerful modulatory effects in a variety of tissues. A major target of action is the skeletal system, where they enhance bone formation and decrease matrix degradation, thus playing a part in the maintenance of bone mass. Because of the potent mitogenic effect of these agents on osteoblasts, recombinant IGF-I (rhIGF-I) and recombinant TGF beta (rhTGF beta) have potential as drugs to stimulate bone formation in the prevention and treatment of osteoporosis. Using biochemical markers, subcutaneous rhIGF-I therapy has been shown to increase bone turnover and bone formation in nonosteoporotic older people. However, a corresponding increase in bone mass has not yet been documented nor have there been reports yet on the effects of systemically administered rhTGF beta in humans. Further investigation is required to define the clinical potential of rhIGF-I and rhTGF beta as therapeutic agents in age-related osteoporosis.

Peptidergic Modulation of Intrathalamic Circuit ActivityIn Vitro: Actions of Cholecystokinin

Cholecystokinin (CCK)-mediated actions on intrathalamic rhythmic activities were examined in an in vitro rat thalamic slice preparation. Single electrical stimuli in the thalamic reticular nucleus (nRt) evoked rhythmic activity (1-15 sec duration) in nRt and the adjacent ventrobasal nucleus (VB). Low CCK concentrations (20-50 nM) suppressed rhythmic oscillations in 43% of experiments but prolonged such activities in the remaining slices. Higher CCK concentrations (100-400 nM) had a predominantly antioscillatory effect. Suppression of oscillations was associated with a relatively large membrane depolarization of nRt neurons that changed their firing mode from phasic (burst) to tonic (single-spike) output. This decreased burst discharge of nRt neurons during CCK application reduced inhibitory drive onto VB neurons from multiple peaked inhibitory postsynaptic currents (IPSCs) to single peaked inhibitory events. We hypothesize that suppression of inhibitory drive onto VB neurons decreases their probability of burst output, which, together with a reduction of nRt burst output, dampens the oscillatory activity. Low CCK concentrations, which produced little or no depolarization of nRt neurons, did not alter the firing mode of the nRt neurons. However, the probability of burst output from nRt neurons in response to subthreshold stimuli was increased in low CCK concentrations, presumably leading to an increase in the number of nRt neurons participating in the rhythmic activity. Our findings suggest that the neuropeptide CCK, by altering the firing characteristics of nRt neurons, has powerful modulatory effects on intrathalamic rhythms; the ultimate action was dependent on CCK concentration and resting state of these cells.

Effect of Power Modulation on Radical Concentration and Uniformity in a Single-Wafer Plasma Reactor

The effect of power modulation oil radical concentration and uniformity in a single-wafer plasma reactor was investigated with a radical transport and reaction model. Plasma etching of silicon using tetrafluoromethane under relatively high pressure (≈l torr) high frequency (13.56 MHz) conditions was taken as an example system. Gas velocity, temperature, and radical concentration profiles were obtained numerically by a finite element method. When compared to a contin uous wave plasma, power modulation can alter the relative concentration of radicals and in turn the each rate and uniformity as well as selectivity and anisotropy Uniformity is improved by power modulation except at high flow rates which, however, result in poor utilization of the feedstock gas.

Feasible eigenvalue sensitivity for large power systems

Traditional eigenvalue sensitivity studies of power systems require the formulation of the system matrix, which lacks sparsity. A new sensitivity analysis approach, derived for a sparse formulation, is presented. Variables that are computed as intermediate results in established eigenvalue programs for power systems, but not used further, are given a new interpretation. The effect of virtually any control action can be assessed on the basis of a single eigenvalue-eigenvector calculation. In particular, the effect of active and reactive power modulation can be found as a multiplication of two or three complex numbers. The method is illustrated by an application to control design for an HVDC link in a large power system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Muscarinic M3 receptors inhibit a leak conductance in rat corticocallosal neurons.

Acetylcholine, acting on muscarinic receptors, has a powerful modulatory effect on neurons in the cerebral cortex. Recent evidence that cortical tissue contains at least four different muscarinic receptor subtypes having different pharmacological properties indicates the value of new investigations of the receptor subtypes that mediate electrophysiological responses. Here we studied the ionic nature and pharmacology of the depolarizing response to acetylcholine in identified corticocallosal neurons in primary culture. This response is the result of a non-rectifying 'leak' K+ conductance which is reduced in the presence of acetylcholine. The relative sensitivity of this conductance change to the antagonists pirenzepine and 4-DAMP suggests that it is mediated by the M3 subtype of muscarinic receptor.

Effects of NBI power modulation on pellet injection into a current free plasma in Heliotron E

Hydrogen pellets are injected into the current free neutral beam injection (NBI) heated plasma in Heliotron E to effectively increase the plasma density and the internal energy. The chord averaged density of the target plasma is about 2 × 1019 m−3, and the density increase by pellet injection is (4 – 6) × 10l9 m−3. During this process the plasma remains stable. Under the present operational conditions, the pellet reaches the central axis: the penetration depth ranges from 27 cm to 35 cm (the magnetic axis corresponds to 30 cm). To optimize the plasma parameters obtainable by pellet injection, the NBI heating power is modulated. It is found that the mode of operation in which pellets are injected at relatively low NBI power followed by a higher-NBI-power phase is preferable to that in which pellets are injected during a constant high power phase. The main reason for this difference is the penetration depth of the pellet in the plasma which determines the deposition profile of particles in the plasma.