Power measurement of noise-initiated Brillouin scattering in optical fibers for sensing applications.

We discuss the measurement of noise-initiated Brillouin scattered power in optical fibers and its application to distributed sensing systems. In particular, we consider the use of Brillouin scattering in the nonlinear regime, demonstrating a novel processing technique that compensates for the nonlinear growth of the scattered signals. The signal-to-noise ratio performance of this technique is evaluated, highlighting the importance of the noise contributed by the random statistics of the scattered field and yielding the conditions for optimum system operation.

Temperature and strain dependence of the power level and frequency of spontaneous Brillouin scattering in optical fibers.

The strain dependence of the optical power of Brillouin scattering in optical fibers has been measured for the first time to our knowledge. Together with measurements of the dependence of Brillouin power on temperature and the variation of Brillouin frequency with temperature and strain, we demonstrate, for what we believe to be the first time, the feasibility of a simultaneous temperature and strain sensor based on spontaneous Brillouin scattering.

Immunohistochemical and biochemical study on the development of the noradrenaline- and adrenaline-storing cells of the adrenal medulla of the rat.

The pre- and postnatal development of the adrenal medulla was examined in the rat by immunohistochemistry and by assay of catecholamines. Immunohistochemistry involved the use of antibodies to noradrenaline (NA), adrenaline (A) and the biosynthesizing enzymes dopamine beta-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT). Adrenal glands were obtained from animals from the 16th day of gestation to the 7th postnatal day at daily intervals, and at the 14th postnatal day, and from adult rats. Tissues were fixed in ice-cold, 4% paraformaldehyde, buffered at pH 7.3. Cryostat sections (7 microns) were stained with the indirect immunofluorescence technique. Adrenals from the same developmental stages were assayed for the presence of DA (dopamine), NA and A by ion-pair reversed-phase liquid chromatography with electrochemical detection. In adult adrenals the majority of the medullary cells (approximately 80%) were highly immunoreactive to A and moderately immunoreactive to NA. They also showed immunoreactivity to both DBH and PNMT, i.e., they are synthesizing and storing A. The remaining cell clusters were only stained by antibodies to DBH and NA (NA-synthesizing and -storing cells). These findings correlate well with the relative concentrations of A and NA as determined by assay. Three developmental phases could be distinguished. In the first phase, the 16th and 17th prenatal day, medullary cells were only immunoreactive to DBH and NA, and only very small amounts of A as compared to NA were found. During the second period, from the 18th prenatal day to 2 or 3 days after birth, all medullary cells were immunoreactive to DBH, NA, PNMT and A, and during this phase the adrenaline concentration increased daily and became the predominant amine on the 20th day of gestation. Adrenaline represented 75% of total catecholamine on the 1st to 3rd day after birth. The third phase started at the 2nd or 3rd postnatal day and was characterized by the presence of an increasing number of medullary cells solely immunoreactive to DBH and NA, hence synthesizing and storing NA. The remaining cells were immunoreactive to DBH, NA, PNMT and A. Postnatally, the relative concentration of A continued to rise reaching 79% by the 4th postnatal day. These results indicate that initially the adrenal medullary cells are synthesizing and storing almost exclusively NA.(ABSTRACT TRUNCATED AT 400 WORDS)