Experimental and Analytical Investigations of the actions taking place in a Synchronous machine during the starting period when the starting Is effected by means of alternating current

The literature on the subject of the present investigation is somewhat meagre. A rotary converter or synchronous motor no! provided with any special starting devices forms, when started from the alternating current side, a type of induction motor whoso Htator is provided with a polyphase winding, and whoso rotor has a single-phase (or single magnetic axis) winding.

Influence of validation schemes in a laser Doppler anemometer period timing device for frequency measurement

The short duration of the Doppler signal and noise content in it necessitate a validation scheme to be incorporated in the electronic processor used for frequency measurement, There are several different validation schemes that can be employed in period timing devices. A detailed study of the influence of these validation schemes on the measured frequency has been reported here. These studies were carried out by using a combination of a fast A/D converter and computer. Doppler bursts obtained from an air flow were digitised and stored on magnetic discs. Suitable computer programs were then used to simulate the performance of period timing devices with different validation schemes and the frequency of the stored bursts were evaluated. It is found that best results are obtained when the validation scheme enables frequency measurement to be made over a large number of cycles within the burst.

Simple period timing device for laser Doppler signals

A period timing device suitable for processing laser Doppler anemometer signals has been described here. The important features of this instrument are: it is inexpensive, simple to operate, and easy to fabricate. When the concentration of scattering particles is low the Doppler signal is in the form of a burst and the Doppler frequency is measured by timing the zero crossings of the signal. But the presence of noise calls for the use of validation criterion, and a 5–8 cycles comparison has been used in this instrument. Validation criterion requires the differential count between the 5 and 8 cycles to be multiplied by predetermined numbers that prescribe the accuracy of measurement. By choosing these numbers to be binary numbers, much simplification in circuit design has been accomplished since this permits the use of shift registers for multiplication. Validation accuracies of 1.6%, 3.2%, 6.3%, and 12.5% are possible with this device. The design presented here is for a 16-bit processor and uses TTL components. By substituting Schottky barrier TTLs the clock frequency can be increased from about 10 to 30 MHz resulting in an extension in the range of the instrument. Review of Scientific Instruments is copyrighted by The American Institute of Physics.

A note on the period of oscillation of non-linear systems

This paper deals with two approximate methods of finding the period of oscillations of non-linear conservative systems excited by step functions. The first method is an extension of the analysis presented by Jonckheere [4] and the second one is based on a weighted bilinear approximation of the non-linear characteristic. An example is presented and the approximate results are compared with the exact results

Simple period timing device for laser Doppler signals

A period timing device suitable for processing laser Doppler anemometer signals has been described here. The important features of this instrument are: it is inexpensive, simple to operate, and easy to fabricate. When the concentration of scattering particles is low the Doppler signal is in the form of a burst and the Doppler frequency is measured by timing the zero crossings of the signal. But the presence of noise calls for the use of validation criterion, and a 5–8 cycles comparison has been used in this instrument. Validation criterion requires the differential count between the 5 and 8 cycles to be multiplied by predetermined numbers that prescribe the accuracy of measurement. By choosing these numbers to be binary numbers, much simplification in circuit design has been accomplished since this permits the use of shift registers for multiplication. Validation accuracies of 1.6%, 3.2%, 6.3%, and 12.5% are possible with this device. The design presented here is for a 16-bit processor and uses TTL components. By substituting Schottky barrier TTLs the clock frequency can be increased from about 10 to 30 MHz resulting in an extension in the range of the instrument. Review of Scientific Instruments is copyrighted by The American Institute of Physics.

A Need for FSH in Maintaining Fertility of Adult Male Subhuman Primates

Adult fertile male bonnet monkeys (Macaca radiata) were continuously deprived of endogenous follicle stimulating hormone (FSH) support for 240 days by injecting them with 1 ml of characterized monkey antiserum to oFSH every 48 hr; control monkeys received during the same period normal monkey serum instead. Testicular function was assessed at periodic intervals by (a) carrying out differential counting of sperm in the ejaculate obtained and (b) determining the hyaluronidase activity as well as in vitro 3H thymidine incorporation into DNA of testicular tissue removed at biopsy. Both the quality (viability and motility) of the sperms voided and the total sperm counts showed marked decreases as a function of time of immunization, the first significant reduction being noted by 100 days. FSH deprivation affected both the biochemical parameters used to test testicular functionality they being reduced at ∼200 days by 50%-60%. The fertility of these monkeys was evaluated at periodic times after 90 days of treatment by means of mating studies. FSH deprivation had rendered the monkeys incapable of impregnating any of the females used. Testosterone and luteinizing hormone (LH) levels remained unchanged following FSH antiserum injection. With cessation of antiserum treatment testicular function and fertility were completely restored to normalcy, indicating that the observed effect was specifically due to FSH deprivation. This study thus provides conclusive evidence for the involvement of FSH in maintenance of testicular function and fertility in the adult male primate.

Effect of rabbit antiserum to ovine LH on reproductive organs in male hamsters and guinea-pigs

Administration of rabbit antiserum to ovine luteinizing hormone to immature hamsters and guinea-pigs resulted in a significant decrease in the weights of testes, seminal vesicle and ventral prostate. The author wishes to thank Prof. N.R. Moudgal for his interest and Family Planning Foundation for financial assistance.

Chronopotentiometry with power-law perturbation functions at an expanding plane electrode with and without a preceding blank period for systems with a coupled first-order homogeneous chemical reaction

The systems formalism is used to obtain the interfacial concentration transients for power-law current input at an expanding plane electrode. The explicit results for the concentration transients obtained here pertain to arbitrary homogeneous reaction schemes coupled to the oxidant and reductant of a single charge-transfer step and the power-law form without and with a preceding blank period (for two types of power-law current profile, say, (i) I(t) = I0(t−t0)q for t greater-or-equal, slanted t0, I(t) = 0 for t < t0; and (ii) I(t) = I0tq for t greater-or-equal, slanted t0, I(t) = 0 for t < t0). Finally the potential transients are obtained using Padé approximants. The results of Galvez et al. (for E, CE, EC, aC) (J. Electroanal. Chem., 132 (1982) 15; 146 (1983) 221, 233, 243), Molina et al. (for E) (J. Electroanal. Chem., 227 (1987) 1 and Kies (for E) (J. Electroanal. Chem., 45 (1973) 71) are obtained as special cases.

Novel reproductive mode in a torrent frog Micrixalus saxicola (Jerdon) from the Western Ghats, India

Reproductive modes in anurans are highly diverse despite external fertilization being a constraint. There are 39 reproductive modes documented so far (Wells, 2007). An apparently new reproductive mode is reported in a torrent frog, Micrixalus saxicola, an endemic and ancient anuran frog of the Western Ghats, considering the type of cavity made inside the lotic water body, involvement of the female in digging the cavity and concealing the eggs.

Reproductive behavior and health in consanguineous marriages

In many regions of Asia and Africa, consanguineous marriages currently account for approximately 20 to 50% of all unions, and preliminary observations indicate that migrants from these areas continue to contract marriages with close relatives when resident in North America and Western Europe. Consanguinity is associated with increased gross fertility, due at least in part to younger maternal age at first livebirth. Morbidity and mortality also may be elevated, resulting in comparable numbers of surviving offspring in consanguineous and nonconsanguineous families. With advances in medicine and public health, genetic disorders will account for an increased proportion of disease worldwide. Predictably, this burden will fall more heavily on countries and communities in which consanguinity is strongly favored, as the result of the expression of deleterious recessive genes. However, studies conducted in such populations indicate that the adverse effects associated with inbreeding are experienced by a minority of families.

Luteal-phase defect induced by deprivation of FSH at a specific period of the follicular phase prevents pregnancy in the bonnet monkey (Macaca radiata)

Female bonnet monkeys were injected i.v. with 25 µl antiserum to FSH on Days 5, 6 or 7 of the cycle: the length of the luteal phase was shortened but there was no alteration in cycle length. Proven fertile females (N = 6) were caged throughout the period of the experiment (6 cycles) with proven fertile males and treated with 25 µl FSH antiserum on Day 7 of each of 3 successive cycles. Out of 18 cycle exposures during the treatment phase, 17 were ovulatory, but no pregnancies occurred. In the post-treatment phase, 5 monkeys became pregnant within 3 cycle exposures. These results show that it is possible to render female monkeys infertile by creating luteal insufficiency and this can be achieved repeatedly in a reproducible manner by depriving the cyclic females of FSH support on Day 7 of consecutive cycles.

Differential reproductive success in Cassia fistula in different habitants-A case of pollinator limitations?

Differences in flower success patterns in two habitat types that differed drastically with respect to rainfall, tree density and species composition were studied at Mudumalai wildlife sanctuary, India. Observations on phenological patterns of two species, Cassia fistula and Gmelina arborea, were made from April 1988 through June 1990. Quantitative data on flower-fruit ratio, insect visitation rates, pollen grain per stigma and the number of fruits per tree were recorded. Data were also collected on the number of pollen deposited on the stigma after different types of bees visited the flower. The data suggested that only carpenter bees (Xylocopa spp) effect pollination in C. fistula. The differences in fruit-flower ratios were attributed to the differences in insect visitation rates to inflorescences between sites. The low pollen number per stigma and the resultant reduction in reproductive success in C. fistula are attributed to the competing species G. arborea receiving more visitations from pollinators in the wetter site. These results suggest that pollinator limitation is another constraint in reproductive success of plants.

Reproductive phenology of a tropical dry forest in Mudumalai, Southern India

1 Flowering and fruiting phenologies of a tropical dry forest in Mudumalai, southern India, were studied between April 1988 and August 1990. Two sites, a wetter site I receiving 1100mm and a drier site II receiving 600mm of rainfall annually, are compared. A total of 286 trees from 38 species at site I and 167 trees from 27 species at site II was marked for phenological observations. There were 11 species common to the two sites. Several hypotheses relating to the evolution of reproductive phenology are tested. 2 Frequency of species flowering attained a peak at site I during the dry season but at site II, where soil moisture may be limiting during the dry months, the peak was during the wet season. At both sites a majority of species flushed leaves and flowered simultaneously. Among various guilds, the bird-pollinated guild showed distinct dry season flowering, which may be related to better advertisement of large flowers to pollinators during the leafless dry phase. The wind-pollinated guild flowered mainly during the wet season, when wind speeds are highest and favourable for pollen transport. The insect-pollinated guild showed no seasonality in flowering in site I but a wet season flowering in site II. 3 Fruiting frequency attained a peak in site I during the late wet season extending into the early dry season; a time-lag correlation showed that fruiting followed rainfall with a lag of about two months. Site II showed a similar fruiting pattern but this was not statistically significant. The dispersal guilds (animal, wind, and explosive passively-dispersed) did not show any clear seasonality in fruiting, except for the animal-dispersed guild which showed wet season fruiting in site I. 4 Hurlbert's overlap index was also calculated in order to look at synchrony in flowering and fruiting irrespective of climatic (dry and wet month) seasonality. In general, overlap in flowering and fruiting guilds was high because of seasonal aggregation. Among the exceptions, at site II the wind-pollinated flowering guild did not show significant overlap between species although flowering aggregated in the wet season. This could be due to the need to avoid heterospecific pollen transfer. 5 Rarer species tended to flower earlier in the dry season and this again could be an adaptation to avoid the risk of heterospecific pollen transfer or competition for pollinators. The more abundant species flowered mainly during the wet season. Species which flower earlier have larger flowers and, having invested more energy in flowers, also have shorter flower to fruit durations.

Secretion of endocrine signals by the primate embryo during the peri-implantation period

Development of preimplantation embryos and blastocyst implantation are critical early events in the establishment of pregnancy. In primates, embryonic signals, secreted during the peri-implantation period, are believed to play a major role in the regulation of embryonic differentiation and implantation. However, only limited progress has been made in the molecular and functional characterization of embryonic signals, partly due to severe paucity of primate embryos and the lack of optimal culture conditions to obtain viable embryo development. Two embryonic (endocrine) secretions, i.e. chorionic gonadotrophin (CG) and gonadotrophin releasing hormone (GnRH) are being studied. This article reviews the current status of knowledge on the recovery and culture of embryos, their secretion of CG, GnRH and other potential endocrine signals and their regulation and physiological role(s) during the peri-implantation period in primates, including humans.