Tunable mechanically induced long-period fiber gratings.

We report the experimental characterization of mechanically induced long-period fiber gratings (LPFG's) made by pressing a plate with periodic grooves against a short length of fiber. This filter, which is simple and inexpensive, exhibits transmission spectra and temperature stability similar to those of photoinduced LPFG's. It also offers the unique advantages of being tunable, erasable, and reconfigurable. Its polarization dependence also makes it useful as a polarizer, although it can also be eliminated with simple mechanical designs.

Non-invasive diagnosis of pregnancy in wild black rhinoceros (Diceros bicornis minor) by faecal steroid analysis.

The objective of this study was to determine whether faecal progestagen measurement could be used to diagnose pregnancy in wild black rhinoceros cows. Immunoreactive 20alpha-progestagens were measured in faecal samples collected regularly (one or two times times per week) from pregnant and non-pregnant wild black rhinoceros females (n = 6) in Zimbabwe. Fresh dung piles deposited by the study animals were serially sampled during prolonged periods of tracking with local game scouts. Samples were stored frozen, and dried prior to methanol extraction. Immunoreactivity in faecal extracts was measured with a 20alpha-dihydroprogesterone enzyme immunoassay and was shown to reflect circulating progesterone concentrations. Mean concentrations of faecal 20alpha-progestagens during each month of gestation were significantly higher than faecal concentrations in non-pregnant animals (P<0.05), except during the second month of gestation. Faecal 20alpha-progestagens remained 5-10 times higher than concentrations in non-pregnant animals from the 4th to 15th month of gestation. It was concluded that regular non-invasive reproductive monitoring of black rhinoceros in the wild was possible and that pregnancy could be accurately diagnosed from the measurement of 20alpha-progestagens in faecal samples. The use of this technique in wild black rhinoceros populations will offer new perspectives for in situ management of this endangered species.

Phase-sensitivity measurement of a 10-sensor array with erbium-doped fiber amplifier telemetry.

We report what are believed to be the first measurements of the phase sensitivity of a fiber sensor array using multiple low-gain remotely pumped amplifiers with an interferometric sensor inserted. The measured phase sensitivities for individual rungs average 5.7 microrad(rms)/ radicalHz and exhibit no dependence on rung number, in agreement with predictions.

The British Association of Head and Neck Oncologists within the wider perspectives of the USA and Europe.

An account is given of the origin and development of the British Association of Head and Neck Oncologists in relation to American and European Societies. Disillusion with the results of treatment and the poor management available for these patients before 1950, led to the formation of head and neck oncologic societies, initially in the USA, to bring about much needed improvements. Similar views were held in the UK and Western Europe which resulted in the gradual establishment of national societies in the 1960s-80s throughout Western Europe and many other countries. It is believed that these societies should continue to develop and influence medical and planning authorities for the benefit of patients diagnosed as having these uncommon, serious, but often curable tumours.

Polarized superfluorescent fiber source.

We report the demonstration of a polarized superfluorescent fiber source (SFS) that increases the power output in the desired linearly polarized component by a factor of 1.76 over that of a standard, unpolarized SFS that uses the same pump power. This increase in efficiency is accomplished by insertion of a low-loss polarizer at an optimum point in the erbium-doped fiber of a standard SFS.

Large-scale interferometric fiber sensor arrays with multiple optical amplifiers.

We report what we believe to be the first laboratory prototype of a fiber sensor array using multiple low-gain (5dB) remotely pumped amplifiers in a 10-rung ladder structure. Incorporating amplifiers improves the system noise figure to less than 20dB, compared with 32dB in an optimized passive array of the same size. Scalability to more than 300sensors per fiber pair while a high dynamic range (1microrad/ sensitivity) is maintained is demonstrated.

Basis for a polarized superfluorescent fiber source with increased efficiency.

We propose to produce a superfluorescent fiber source (SFS) with a linearly polarized output by inserting a discrete polarizer near the middle of a polarization-maintaining Er-doped fiber. We show that with a relatively low-loss polarizer (<0.5 dB) the output power of the polarized SFS is predicted to approach that of a standard, unpolarized SFS, i.e., the power of the desired polarization mode is nearly doubled. The efficiency of this source depends weakly on the polarizer location and extinction ratio, although it depends strongly on its insertion loss.

Modeling of ion pairs in erbium-doped fiber amplifiers.

The effects of Er-Er pairs on the characteristics of Er-doped fiber amplifiers are analyzed theoretically. Pairs are found to have little effect on the amplifier optimum length, signal saturation power, and noise figure (at constant gain) but to cause significant reduction in the gain, even at residual levels, quantitatively consistent with fiber laser measurements. A maximum tolerable fraction of paired ions near 8%, corresponding to approximately 400 mole parts in 10(6) Er(2)O(3), is predicted for near-optimum gain efficiency in Al-Ge silica fibers.

Determination of ovarian cycle in Goeldi's monkey (Callimico goeldii) via the measurement of steroids and peptides in plasma and urine.

Goeldi's monkey (Callimico goeldii) is an endangered species of New World primate. The present study provides the first description of the non-conception ovarian cycle in this species based on circulating reproductive steroid and peptide hormones. The data obtained were used to validate a non-invasive system for monitoring cyclicity based on urinary reproductive steroid metabolites. Nine sexually mature females were studied. In three females, matched blood and urine samples were collected once every 2-3 days for 90-120 days; in three other females, matched blood and urine samples were collected daily for 14-20 days for one peri-ovulatory period; and in the remaining three females, urine samples only were collected once every 1-3 days for 40-60 days. Plasma progesterone, oestrone-3-conjugates and bioactive LH were measured, in addition to urinary pregnanediol-3 alpha-glucuronide and oestrone-3-conjugates. The mean maximum concentration of plasma LH occurred 1-2 days before a significant rise in plasma progesterone, which was considered to occur 1 day after ovulation. On the basis of plasma progesterone titres, the duration of the ovarian cycle was estimated as 23.9 +/- 0.4 days (n = 9), and constituted a follicular phase of 10.7 +/- 0.3 days and a luteal phase of 13.5 +/- 0.3 days. Urinary pregnanediol-3 alpha-glucuronide demonstrated a high correlation with plasma progesterone (r = 0.8), and demonstrated a significant rise at the same time as plasma progesterone.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-invasive monitoring of ovarian function in Asian elephants (Elephas maximus) by measurement of urinary 5 beta-pregnanetriol.

The development of an enzymeimmunoassay for 5 beta-pregnanetriol and its use for non-invasive monitoring of reproductive cycles in Asian elephants is described. Gas chromatography-mass spectrometry (GCMS) and high performance liquid chromatography (HPLC) confirmed the presence of 5 beta-pregnane-3 alpha,17 alpha,20 alpha/beta-triols as the two most abundant urinary progesterone metabolites. The assay developed used the antiserum anti-5 beta-pregnane-17 alpha,20 alpha-diol-3 alpha-gamma l glucuronide but was designed to measure the free steroid in urine samples after hydrolysis and extraction. HPLC confirmed the presence of immunoreactive pregnanetriol in urine, but indicated that the measurement was nonspecific. Immunoreactive pregnanetriol concentrations were significantly correlated with the concentrations of both progesterone (r = 0.98, n = 269, P < 0.01) and 17 alpha-hydroxyprogesterone (r = 0.95, n = 205, P < 0.01), the metabolic precursor of pregnanetriol. The mean +/- SEM deviation of cycles as determined by measurements of plasma progesterone, 17 alpha-hydroxyprogesterone and urinary pregnanetriol, respectively, were 15.54 +/- 1.5 (n = 23, where n = number of cycles), 15.21 +/- 1.7 (n = 15) and 15.45 +/- 0.94 weeks (n = 20). These results demonstrate that it is possible to monitor ovarian function in Asian elephants by the measurement of urinary immunoreactive pregnanetriol concentrations.

Developmental changes in marmoset granulosa cell responsiveness to insulin-like growth factor-I: interactions with follicle-stimulating hormone and estradiol.

The biological actions of insulin-like growth factor-I (IGF-I) on granulosa cell steroidogenesis at defined stages of preovulatory follicular development in the marmoset monkey were examined. Studies were carried out by primary cell culture of granulosa cells derived from small antral (0.5-1.mm diameter) and large preovulatory (2-3.mm diameter) follicles collected during the mid-late follicular phase of the ovarian cycle. IGF-I (0.3-100 ng/ml) had no effect on progesterone accumulation or aromatase activity during 48-h culture of granulosa cells from small follicles. Progesterone accumulation by cells from large follicles was also unaffected by IGF-I over the same time period, although aromatase activity was stimulated in a dose-dependent manner (18-fold increase over basal levels with a maximally stimulatory dose of 30 ng IGF-I/ml). In contrast, granulosa cells from small and large follicles responded to IGF-I in terms of both progesterone accumulation and aromatase activity after longer periods of culture (4 days for progesterone; 6 days for aromatase). Concurrent treatment of granulosa cells from small follicles with estradiol (10(-7) M) enhanced the dose-dependent actions of IGF-I on both indices of steroidogenesis and advanced the time at which IGF-I stimulated activity was first detectable. The effects of estradiol on granulosa cell IGF-I responsiveness were independent of cell number. A synergistic action of IGF-I on FSH-stimulated granulosa cell steroidogenesis was not apparent.(ABSTRACT TRUNCATED AT 250 WORDS)

Larynx preservation after initial non-cisplatin containing combination chemotherapy plus radiotherapy, as opposed to surgical intervention with or without radiotherapy in previously untreated advanced head and neck cancer: final analysis after 12 years follow-up.

After a median follow-up of 12 years, median overall survival of 73 patients with advanced squamous cell carcinoma of the larynx was 65 months. The 61 per cent of patients responding to two courses of initial schedule A combination chemotherapy, not including cisplatin, and the 81 per cent of patients achieving a final complete remission after definitive local therapy, had median overall survival figures of 95 and 97 months respectively. Overall survival and relapse-free survival in 51 patients treated with radiotherapy only with larynx preservation, were not significantly different from the 21 patients who completed their surgery with pre- or post-operative radiotherapy; median overall figures were 71 versus 65 months. These data add weight to our proposal that use of initial combination chemotherapy followed by radiotherapy may eliminate the need for radical surgery, so preserving the larynx in patients with advanced disease, and provides evidence of some long-term benefit with 32 per cent of this entire group surviving 12 years.

Synthetic heterodyne detection in a fiber-optic ring-laser gyro.

A synthetic heterodyne detection scheme for ring-laser gyros to sense both rotation rate and direction is presented. This scheme is compatible with the sinusoidal push-pull phase-modulation technique for suppressing frequency locking. The good experimental results achieved in a fiber-optic Brillouin ring-laser gyro show the potential of this detection scheme in applications.

Lock-in reduction technique for fiber-optic ring laser gyros.

We have demonstrated a Brillouin fiber-optic gyro that utilizes push-pull phase modulation in the ring cavity to suppress frequency locking. This in-line modulation allows an all-fiber system with optical reciprocity. A tenfold reduction of the width of the lock-in range is observed experimentally.

Effects of oestradiol-17 beta on FSH-stimulated steroidogenesis in cultured marmoset granulosa cells.

A role for oestradiol in ovarian follicular development is well recognized. However, a number of disparate effects have been reported for the action of oestradiol in the primate ovary. To investigate this further, we have examined the effects of oestradiol on the differentiation of granulosa cells isolated from small (0.5-1 mm) antral follicles obtained from the ovaries of prepubertal marmoset monkeys (Callithrix jacchus). Granulosa cells were co-cultured with oestradiol and human FSH (hFSH) for 48 h, or were pretreated with oestradiol for 48 h before addition of gonadotrophin for a further 48 h. Oestradiol (0.01-100 nmol/l) had no effect on basal or hFSH-stimulated progesterone accumulation and aromatase activity when the hormones were added concurrently. Furthermore, oestradiol did not influence the ability of hFSH to induce LH/human chorionic gonadotrophin (hCG) responsiveness in immature granulosa cells. The absence of synergism between oestradiol and hFSH in the induction of marmoset granulosa cell differentiation was independent of the presence of phenol red in culture medium. However, gonadotrophin-stimulated steroidogenesis was attenuated when cells were cultured in the presence of phenol red compared with in its absence; this effect was more pronounced for gonadotrophin-stimulated aromatase activity but was evident for LH/hCG-stimulated progesterone accumulation at higher doses of hCG (10 and 100 ng/ml). An effect of phenol red on basal steroidogenesis was less obvious.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of partial laryngectomy after irradiation in the treatment of laryngeal cancer: a view from the United Kingdom.

This retrospective study evaluates the use of conservation surgical salvage techniques in cases of early (T1 and T2) laryngeal cancer after full-dose external irradiation. Fifty patients in one London hospital and 68 patients in another were studied for the period 1963 to 1988. Treatment policy directed that the majority of limited glottic and supraglottic tumors should be treated initially by external irradiation. The small number of glottic treatment failures had a good chance of salvage by vertical partial laryngectomy if recurrence or a new primary was detected early. Recurrence of supraglottic cancer was salvaged occasionally by horizontal partial laryngectomy if strict indications were observed. Total laryngectomy remained the final minority salvage option.