Ultra-high frequency

The non-storage oscilloscope can be found in most electronic test situations, from sophisticated research laboratories to production engineering plants. The storage unit is most widely used in medical work and in electromechanical applications, particularly where very high-speed transients need to be recorded, while, as noted above, the sampling type finds its main use in the evaluation of ultra-high-frequency equipment. 

Ultra-sound emissions typically occur when male rodents are exposed to female odours or altricial neonates to maternal sources (Whitney, 1974 Conely and Bell, 1978). Without the VNO, sexually inexperienced male mice do not utter emissions at ultra-high frequencies (UHF), whereas those with prior experience vocalise after VN-x, as discussed above (Chap. 5). Female mouse urine contains a unique UHF-eliciting component which is non-volatile but ephemeral (Sipos et al., 1995). The signal is degraded by oxidation and disappears within 15 to 18 hours of deposition. Direct contact with freshly voided urine must occur before males will vocalise (sexually experienced or inexperienced). At least one of the olfactory systems is needed for UHF to be elicited by fresh urine complete deafferentation abolishes the response (Sipos et al., 1993). Exposure to females permits UHF to be elicited by other than chemical cues (Labov and Wysocki, 1989). Nocturnal or cryptic species conceivably use ultrasound to advertise male presence whether this is to deter other males or assist with female location is unclear. 

Geyer L., et al. (1978). Effect of ultra high frequency and male urine on female rat readiness to mate. J Comp Physiol Psychol 92, 457-462. 

Vomeronasal Receptor (Neurone) Vomeronasal System Vomeronasalectomy Testosterone Ultra-High Frequency... 

Recent studies by Liu et al. [82] have expanded the scope of using NMR to detect branch lengths up to 10 carbon atoms. Liu et al. [82] were able to assign chemical shits values to carbon atoms in a branch longer than six carbons by using ultra-high frequency 13C-NMR (188.6 MHz). 

Microwave detectors Emit ultra-high-frequency radio waves, and the detector senses any changes in these waves as they are reflected throughout the protected space. Microwaves can penetrate through walls, and thus a unit placed in one location may be able to protect multiple rooms. 

For a monatomic gas, where the heat capacity involves only translational energy, V is independent of sound oscillation frequency (except at ultra-high frequencies, where a classical visco-thermal dispersion sets in). For a relaxing polyatomic gas this is no longer so. At sound frequencies, where the period of the oscillation becomes comparable with the relaxation time for one of the forms of internal energy, the internal temperature lags behind the translational temperature throughout the compression-rarefaction cycle, and the effective values of CT and V in equation (3) become frequency dependent. This phenomenon occurs at medium ultrasonic frequencies, and is known as ultrasonic dispersion. It is accompanied by... 

N. I. Mukhurov, in Proceedings of Electronics and Radiophysics of Ultra-High Frequencies, 24-28 May 1999, IEEE, St. Petersburg, Russia (1999) 323. 

Carotenoids are still highly topical systems for research. Both Sj Sq and S2 Sq electronic relaxation process in carotenoids with 7 to 11 conjugated double bonds have been subjected to very comprehensive study . The lifetime of the S2 state of P-carotene in CS2. measured by a femtosecond absorption method, is found to be 200-250 fs at room temperature . Fs time resolved CARS from p-carotene in solution shows the occurrence of ultra-high frequency (llTHz) beating phenomena and sub-ps vibrational relaxation. The same technique has been used to observe solvent effects on the a C=C stretching mode in the 2 Ag excited state of P-carotene and two derivatives . A similar study has been made with several derivatives of P-carotene. ... 

USE In electrical circuit interrupters. In electronic ultra-high frequency piping. 

EINECS 219854-2 Elegas Esaflon Hexafluorure de soufre HSDB 825 Sulfur fluoride, (OC-6-11)- Sulfur fluoride (SFe), pC-6-11)- Sulfur hexafluoride Sulphur hexafluoride UN1080. Used in electrical circuit breakers and in electronic ultra-high frequency piping. Gas mp = -51° soluble in oil. Montedison UK. 

With the extension of radio-communication to ultra-high frequencies the use of point-contact crystal rectifiers in telecommunication circuits has become an established practice. Both silicon and germanium (p. 174) crystal rectifiers are now in use. 

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