Delta frequency

McGinty, D., Szymusiak, R., Thomson, D. (1994). Preoptic/anterior hypothalamic warming increases EEG delta frequency activity within non-rapid eye movmement sleep. Brain Res. 667, 273-7. 

Electrophysiological effects Extracts of hypericum were examined for their electrophysiological effects in animals. The onset of effects occurred 3-4 hours after administration. Frequencies affected first were in the alpha range and were maximal in the frontal cortex (Dimpfel and Hofmann 1995). Another study examined the EEG effects for two hypericum extracts in rats one extract high in hyperforin and lacking naphthodi-anthrones (C02), and another extract (LI 160) low in hyperforin. Both extracts showed similar early alpha effects, but only LI 160 had a late effect of increased delta frequencies. The alpha effects are comparable to... 

Darko DF, Miller JC, Gallen C, White J, Koziol J, Brown SJ, Hayduk, Atkinson JH, Assmus J, Munnel DT, Naitotl P, McCutchen A, Mitler MM. Sleep electroencephalogram delta-frequency amplitude, night plasma levels of tumor necrosis fac-... 

The resulting tangent delta/frequency relation of the SSBR sample at 18°C is shown in Figure 5.9. These results indicate that such a shifting possibility offers data extending over more than eleven decades of frequency while the actual measurements were performed over only four decades. 

Tan delta/frequency/temperature relation of vulcanised SSBR (no carbon black)... 

EEC frequency wave band powers Delta frequency... 

The effect of smart fabric 4 11.9.4.1 EEG frequency wave band powers Delta frequency... 

In the ease of the brain, the initial synchronization at a particular frequency band corresponds to a particular functional state of the body. In the particular case of the experiment on anaesthetized rats [20], this state corresponds to the state of deep anesthesia (aeeompanied by synchronization in the delta frequency band). In this... 

These preliminary results show that all maximum DP occurred in delta frequency band. This can result a difficult analysis to differentiate the signals for each task since this study focuses on having only one electrode attach on scalp. 

J Cornfield. In DL Meyer, RO Collier, eds. The Frequency Theory of Probability, Bayes Theorem, and Sequential Clinical Trials. Bloomington, In Phi Delta Kappa, 1970, pp 1-28. 

The (5-part in (2.50) is responsible for elastic scattering, while the second term, proportional to the Fourier transform of C(t), leads to the gain and loss spectral lines. When the system exercises undamped oscillations with frequency Aq, this leads to two delta peaks in the structure factor. 

The NMR chart is calibrated in delta units (5), where 15=1 ppm of spectrometer frequency. Tetramethylsilane (TMS) is used as a reference point because it shows both 1H and 13C absorptions at unusually high values of the applied magnetic field. The TMS absorption occurs at the right-hand (upfield) side of the chart and is arbitrarily assigned a value of 0 5. 

Chemical shift (Section 13.3) The position on the NMR chart where a nucleus absorbs. By convention, the chemical shift of tetramethylsilane (TMS) is set at zero, and all other absorptions usually occur downfield (to the left on the chart). Chemical shifts are expressed in delta units. 5, w here 1 5 equals 1 ppm of the spectrometer operating frequency. 

Delta scale (Section 13.3) An arbitrary scale used to calibrate NMR charts. One delta unit (5) is equal to l part per million (ppm) of the spectrometer operating frequency. 

We say that each group of protons has a characteristic chemical shift. The measurement of the chemical shift helps to identify the type of group responsible for the absorption and indicates what groups are present in the molecule. The chemical shift of a group of lines is expressed in terms of the 8 scale (delta scale), which measures the difference in absorption frequency between the sample (v) and a standard (v°) ... 

Energy loss under low frequency conditions is often used as a key factor for evaluating elastomer compositions. In this respect, the rolling resistance and skidding properties are usually evaluated by tan delta (tan 8) at 60°C and 0°C, where the 60°C value correlates with low frequency loss and 0°C correlates with skid resistance (high frequency loss). 

As we relax in preparation for and pass into sleep, the active desynchronised awake EEG characterised by the low-amplitude (5-10 pV) high-frequency (10-30 Hz) beta waves becomes progressively more synchronised giving larger (20-30 pV) and slower (8-12 Hz) alpha waves, and then even slower (1-4 Hz) and bigger (30-150 pV) delta waves. This so-called slow-wave sleep is interrupted at intervals of some 1-2h by the break-up and desynchronisation of the EEG into an awake-like pattern. Since this is accompanied by rapid eye movements, even though sleep persists and can be deeper, the phase is known as rapid eye movement, REM or paradoxical, sleep. It is a time when dreaming occurs and when memory may be secured. 

Administration of HA and its effect on sleep-wakefulness Local application of HA (5, 30 and 60 pg) in the TMN region of cats increased the latency to sleep, increased arousal, and reduced NREM sleep in a site-specific, dose-dependent manner. The highest dose produced the maximal effect, which lasted for 6 h. The HA-induced arousal was completely blocked when the cats were pretreated intraperitoneally with the Hi receptor antagonist mepyramine (Lin et at, 1986, 1988). In rats, intraventricular administration of HA blocked the increase in delta and theta activity (0-6 Hz) in the EEG induced by repeated low-frequency stimulation of the midbrain reticular formation. This effect was blocked if specific thalamic nuclei were lesioned (Tasaka et at, 1993) or by simultaneous administration of an Hi receptor antagonist, but not by an H2 receptor antagonist (Tasaka et at, 1989). Application of HA... 

The obvious approach to answering this question is to remove an electron from this orbital and observe the effect on, for example, the metal-metal stretching frequency or metal-metal bond distance. Of course, removal of an electron from the delta bonding orbital creates a positive molecular ion for which determination of these properties may not be possible using normal techniques. In those cases where the ion is sufficiently stable that these properties can be measured, the meaning of the information may be clouded by changes in intermolecular interactions or other internal factors. 

The important point to remember is that an electron in the delta-bonding orbital of M02(O2CCH3)if has a substantial influence on the strength of the metal-metal interaction. This influence is directly evidenced by the metal-metal vibrational fine structure observed with ionization from the delta orbital, which shows a lowering of the metal-metal stretching frequency and a lengthening of the equilibrium metal-metal bond distance. 

The homonuclear dipolar recoupling technique of radio frequency-driven recoupling (RFDR) involves a hard n pulse per rotor period and its recoupling mechanism is based on the modulation of chemical shift difference [35-37]. When the delta-pulse approximation is relaxed so that the pulse width of the 7t pulse is about one-third of the rotor period, the so-called finite-pulse RFDR (fpRFDR) could selectively reintroduce the homonuclear dipole-dipole interaction under fast MAS conditions [38], Because the recoupling mechanism of fpRFDR does not require the presence of chemical shift difference, it can be applied to study samples with a singly labeled site. For the study of amyloid fibrils, the technique of fpRFDR is usually applied in a constant-time framework (see below). 

---