Late Surge Research Articles

High-pressure pyrolysis and CO 2-gasification of coal maceral concentrates: conversions and char combustion reactivities

The gasification behaviour of maceral concentrates was examined in a fixed-bed and a wire-mesh reactor. ‘Extents of gasification’ were calculated by subtracting sample weight loss during pyrolysis (He) from weight loss in CO 2-gasification. The effect of holding time (10 and 200 s) and pressure (1 and 20 bar) on conversions and on combustion reactivities of chars were studied. During short hold-time gasification experiments (10 s), liptinites gave the highest conversions, followed by the vitrinites and the inertinites. Vitrinite conversions decreased sharply above 90% elemental-C content. Extents of gasification were found to be in the order: vitrinites>liptinites>inertinites. However, at 200 s, a marked increase in inertinite conversion translated into a clear change of relative ordering to: inertinites>vitrinites>liptinites. The high gasification reactivities of inertinites at longer times appear to be related to a more rigid and porous structure, but the late surge suggests that an induction period is needed. More detailed time series data are required. Relative combustion reactivities of chars were generally observed to decrease with (i) pressure, (ii) time at temperature and (iii) increasing elemental carbon content. The data indicated that orders of gasification reactivities may be predicted from the order of combustion reactivities of pyrolysis chars. Inertinite concentrate chars were more reactive. However, the difference in reactivity between inertinite chars and other samples was reduced when the inertinites were heated rapidly—possibly owing to melting at the higher heating rates.

Studies on the ecology of the yellow stem borer, Scirpophaga incertulas (Walker) (Pyralidae), in deepwater rice in Bangladesh

The yellow stem borer, Scirpophaga incertulas (Walker), emerged as the dominant pest of deepwater rice in an intensive 4-year ecological study in two farmers' fields in central Bangladesh. There were six annual broods. In brood 1 developing in transplanted dry season rice and brood 2 migrating to preflooded deepwater rice, the population density and level of stem damage were low. Borer populations built up in broods 3, 4 and 5 in flooded deepwater rice to reach densities of 16–52 immatures, m −2, which damaged 33–80% of the stems. Borer populations declined in brood 6 at the end of the deepwater rice season, the larvae entering diapause in the field stubbles. The major factors regulating the populations were as follows: the incidence of weather extremes (temperatures 34 °C with relative humidity < 70%) before flooding which are lethal to eggs and first instars; the presence of succulent, elongating stems which are-favourable for larval penetration and development; the occurrence of rapid water rises (6–8 cm day −1) which drown the immature stages; the activity of natural enemies, particularly the complex of egg parasitoids, and spider and orthopteran predators; and the harvesting and threshing operations which kill many diapausing larvae in the stems. An early season population outbreak in 1977 was associated with exceptionally mild, wet weather; the highest population density and level of stem damage followed a late surge of flooding in 1980 that produced a second flush in elongating stems. The ecological studies revealed two occasions during the season when control measures might be feasible.

Expression of Messenger Ribonucleic Acid for Inhibin Subunits and Ovarian Secretion of Inhibin and Estradiol at Various Stages of the Sheep Estrous Cycle1

The relationship between expression of inhibin mRNA and ovarian secretion of estradiol (E2) and immunoactive inhibin was investigated at midluteal phase and throughout the follicular phase of the sheep estrous cycle. At laparotomy, timed samples of ovarian blood were collected and ovaries were removed from 39 Scottish Blackface ewes (ovulation rate 1.3 +/- 0.1) on Day 10 of the luteal phase or 24, 48, 60, 72, or 84 h after injection of cloprostenol (PG; 100 micrograms) on Days 10-12. Ovaries were removed and fixed for in situ hybridization using 35S-labeled antisense riboprobes transcribed from inhibin alpha, beta A, and beta B cDNAs. LH, E2, and inhibin concentrations were determined by RIA. On the basis of peripheral LH levels and the presence of estrogen-active follicles (E-A; > or = 3 mm in diameter secreting > 1 ng/min E2) or recent ovulations, animals were grouped as follows: presurge (24 or 48 h post-PG; LH < 5 ng/ml; n = 7), midsurge (with E-A; LH > 5 ng/ml; n = 6), late surge (large follicle not E-A; LH > 5 ng/ml; n = 4), postsurge (large follicle not E-A; LH < 5 ng/ml; n = 7), and postovulation (n = 10). As expected, E2 secretion by the "active" ovary (containing preovulatory follicle) tended to increase with follicular development such that secretion was maximal at midsurge and then declined. E2 secretion by the "inactive" ovary was low at all stages. Immunoactive inhibin, in contrast, was secreted in substantial quantities by both ovaries, although secretion from active ovaries was higher at all stages (p < 0.05). Effects of stage on secretion were not significant, but immunoactive inhibin secretion from active ovaries was high in postsurge animals when E2 secretion was very low. Hybridization for inhibin mRNA was specific for granulosa cells of antral follicles. While most sheep in the luteal (4 of 5), presurge (2 of 3), and midsurge groups (5 of 5) had at least one inhibin-positive large follicle (expressing both alpha- and beta-subunit mRNA), none were present between the LH surge and ovulation (late and postsurge groups). Inhibin mRNA was undetectable in midcycle CL, but 4 of 10 recent ovulations hybridized weakly with the alpha probe and one very weakly with the beta A probe. The mean number of inhibin-positive large follicles per animal (in those having at least one) was 1.3 +/- 0.15 (n = 15 ewes).(ABSTRACT TRUNCATED AT 400 WORDS)

The 1992 Elections &amp; the Future of American Politics

Through most of the last year, one of the favorite pastimes of candidates, consultants, and commentators was to speculate about which past election campaign presented the most compelling analogy to that of 1992. George Bush and his advisors had originally hoped, of course, that 1992 would be a replay of 1988, and that they could win the presidency by portraying their opponent as an unvarnished and unrepentant liberal. When that did not seem to work, Bush decided that the proper comparison was actually with 1948, when an embattled incumbent had somehow managed to pull off a late surge and an upset victory. The Democrats, for their part, saw a much closer parallel with 1932, with YouKnow-Who in the role of Herbert Hoover. At last September's American Political Science Association convention, I heard someone draw an extended comparison between 1992 and 1912, a suggestion that struck me as far-fetched at the time, but now seems a good deal more plausible. After eight years in office, the analogy went, a highly popular Republican president steps down and turns the White House over to a vastly more ineffective successor, a man of considerable experience who seems, nonetheless, remarkably out of place in the office he has now come to occupy. The result is that, four years later, there is a three-candidate race for the presidency and a Democrat gets elected with only a bit more than 40 percent of the popular vote. No election, of course, is ever simply a replay of the past. Every presidential campaign has important elements of continuity and tradition, but

Dynamic changes in the density of radial glial fibers of the developing murine cerebral wall: a quantitative immunohistological analysis.

The density of radial glial fibers in the developing murine cerebral wall decreases dramatically during the terminal week of gestation. The present analysis characterizes these variations of fiber density quantitatively. Radial glial fibers were stained with monoclonal antibody RC2. Fibers were counted in a standard area of 2,000 microns2, passing orthogonally to the fiber long axis. At E14, fiber density is maximum and relatively uniform throughout the full width of the cerebral wall. Subsequently, the overall glial fiber density decreases and fiber density gradients emerge in the transmural span of fibers. These radial fiber density gradients are marked by sharp declines at the level of the ventricular-subventricular zone and in the zone of transition between intermediate zone (IZ) and cortical plate. In the interval E14-P0, the decrease in densities of fibers crossing the IZ is commensurate with the predicted diluting effects of tissue expansion with growth. By contrast, the decrease in fiber densities in ascent across the cortical plate beyond E14 through E17 exceeds that predicted by growth. The observations suggest that a substantial population of radial glial fibers do not span the full ventricular zone to the cerebral surface. A major contingent appears to extend only as far as the external sagittal stratum/subplate through E16. Subsequently, at a time when supragranular cortical layers are being assembled, the full set of fibers appears to extend more uniformly through the cortical strata. The late surge of fibers would be appropriate to the intercalation of groupings of neurons of the supragranular layers.

Time-dependent changes in beta-endorphin-stimulated prolactin release during pregnancy.

Endogenous opioid peptides (EOPs) stimulate prolactin (PRL) release in various physiological conditions in the rat. Moreover, EOPs are essential in initiating and maintaining the nocturnal PRL surges that occur over the first half of gestation in the rat. The purpose of this study was to investigate the potential role of the opioid beta-endorphin (beta-End) in mediating the nocturnal PRL surges. Day 8 pregnant rats received an infusion of 2.5, 10, 25 or 100 ng/microliters/min beta-End intracerebroventricularly (i.c.v.) for 15 min at 12.00 h, an intersurge period. PRL increased in a dose-dependent manner and from this, the largest dose was used in subsequent experiments to ensure maximal opioid receptor stimulation. The next experiment defined the temporal sensitivity of the neuroendocrine system regulating PRL surges to exogenous beta-End. Day 8 pregnant rats showed dramatic PRL responses to beta-End when given at midnight (presurge) or 12.00 h (intersurge), but greatly attenuated responses at 02.00 h (early surge) and 04.00 h (late surge). Animals treated at 06.00 h (postsurge) showed recovered responsiveness to beta-End. To determine what may account for the significantly lower PRL increases to beta-End during the surge, day 8 pregnant rats received 100 mg/microliters/min beta-End i.c.v. for 15 min at 10.00 h, and then again at 12.00 h. All animals showed PRL increases greater than 1,140 ng/ml at 10.00 h, but the subsequent response to beta-End at 12.00 h was reduced by 70%. In another experiment, beta-End was infused at midnight and the animals were monitored for a subsequent endogenous nocturnal PRL surge.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of prenatal exposure to ethanol on the development of cerebral cortex: I. Neuronal generation.

Prenatal exposure to ethanol causes profound disruptions in the development of the cerebral cortex. Therefore, the effect of in utero ethanol exposure on the generation of neurons was determined. Pregnant rats were fed a liquid diet in which ethanol constituted 37.5% of the total caloric content (Et) or pair-fed an isocaloric control diet (Ct) from gestational day (GD) 6 to the day of birth. The time of origin of cortical neurons was determined in the mature pups of females injected with [3H]thymidine on one day during the period from GD 10 to the day of birth. The brains were processed by standard autoradiographic techniques. Ethanol exposure produced multiple defects in neuronal ontogeny. The period of generation was 1-2 days later for Et-treated rats than for rats exposed prenatally to either control diet. Moreover, the generation period was 1-2 days longer in Et-treated rats. The numbers of neurons generated on a specific day was altered; from GD 12-19 significantly fewer neurons were generated in Et-treated rats than in Ct-treated rats, whereas after GD 19 more neurons were born. The distribution of neurons generated on a specific day was disrupted; most notable was the distribution of late-generated neurons in deep cortex of Et-treated rats rather than in superficial cortex as they are in controls. Cortical neurons in Et-treated rats tended to be smaller than in Ct-treated rats, particularly early generated neurons in deep cortex. The late-generated neurons in Et-treated rats were of similar size to those in Ct-treated rats despite their abnormal position in deep cortex. Neurons in Ct-treated rats tended to be rounder than those in Et-treated rats which were more polarized in the radial orientation. A proliferation index, which was based on the amount of autoradiographic signal over each labeled neuron, indicated that an additional, late surge in proliferative activity occurred in Et-treated rats on GD 20-21. The amount of [3H]thymidine incorporated each day was determined by biochemical analyses. In Ct-treated rats, incorporation increased to a maximum on GD 17 and decreased thereafter. In Et-treated rats, there were two maxima, the first on GD 18 and the second on GD 20. These data fully support the findings of the autoradiographic analyses. The present data show that neuronal generation is profoundly affected by ethanol. Such disturbances result from ethanol-induced abnormalities in neuronal proliferation and migration.

Oil and Gas Developments in Western Canada in 1982

In 1982, petroleum industry activity in western Canada continued to decline as a result of economic recession, dropping oil and gas prices, high interest rates, and a worldwide oil surplus. Many smaller companies disappeared, and staff cuts were common throughout the industry. The total number of wells drilled dropped 9% to 6,285. Exploratory drilling decreased by 26% to 2,288 wells, whereas development drilling increased 4% to 3,997 wells. The exploratory success rate increased from 62 to 65% in 1982, with 761 oil discoveries and 732 gas discoveries. The development success rate increased slightly from 88 to 89%, with 1,742 oil completions and 1,823 gas completions. A late surge in drilling resulted from provincial and federal incentive programs designed to stimulate act vity. Average well depth decreased in all areas, and total revenue from land sales continued to plummet. Alberta land sale bonuses totaled $334 million(FOOTNOTE 4), British Columbia $17 million, Saskatchewan $34 million, and Manitoba $1 million. Average price paid per hectare dropped substantially in the 3 westernmost provinces, but increased by 75% in Manitoba. Number of hectares for sale declined in all areas. Downward exploratory drilling trends, which began in 1981, were accentuated in 1982. Alberta, Saskatchewan, and British Columbia activity dropped markedly, but Manitoba activity more than doubled. In Alberta, drilling was more cautious, with increased development drilling and fewer dry holes. A significant Devonian pinnacle reef oil discovery was made by Gulf Canada in the Fenn-Big Valley-Rumsey area, and major activity continued to be concentrated in the Peace River arch, Shekilie, and West Pembina areas. The $13.5 billion Alsands project was canceled. No discoveries of major significance were made in either British Columbia or Saskatchewan. Manitoba activity continued to soar for the third consecutive year as a result of the 1980 Jurassic oil discovery at Waskada. In the Arctic Islands, a major stepout oil discovery was made at Cisco, off Lougheed Island, and gas was discovered at Sculpin, near Ellef Ringnes Island. Beaufort Sea stepout oil discoveries were made at West Atkinson and Tarsiut. Delineation drilling on the Tarsiut structure has been disappointing and estimated reserves are less than anticipated. Future major exploration activity in the Beaufort Sea will continue as a result of several large farmouts by Esso and Gulf to Canadian consortiums. Esso also has a major development drilling project in the old Norman Wells oil field astride the Mackenzie River. The year 1982 was a pronounced continuation of 1981, with exploration interest shifting from the provinces to the northern and eastern frontiers. Within the provinces, drilling shifted markedly to oil plays, because of the depressed gas market, while expenditures were down significantly. The downturn in exploration appears to have ended, in part due to provincial drilling incentives, but no major improvement in activity is predicted for 1983.

Development of estradiol-positive feedback on luteinizing hormone release in the female rat: a quantitative study.

Experiments were conducted to study, in a quantitative manner, the development of estradiol (E2)-positive feedback on LH release in the female rat. A Silastic capsule (20 mm in length/100 g BW) containing E2 dissolved in corn oil (400 micrograms/ml) reproduced first proestrous levels of serum E2 when implanted sc in juvenile rats of different ages (days 20-32). When similar capsules were implanted in infantile rats (days 10-18), serum E2, measured 2 days later, was found to be extremely elevated in 12- and 14-day-old rats (4-6 times higher than first proestrous levels), declining thereafter so that in 16- to 20-day-old rats the levels were only 2-fold greater than proestrous values. Serum levels of alpha-fetoprotein decreased markedly between days 12-28, and both normal and implant-produced serum E2 levels paralleled the decline in the protein titers. However, calculation of the total E2 binding capacity of alpha-fetoprotein indicated that in addition to binding to this protein, there are additional factors responsible for the persistence of E2 in the serum of infantile rats. A LH surge could not be induced in 12- or 14-day-old rats by a 48-h E2 pulse, despite the presence of substantial amounts of free E2, which exerted profound negative feedback effects. Between days 16-20, only E2 levels that were at least 2-fold higher than first proestrous values were effective in inducing a LH surge. Between days 22-34, a LH surge was elicited by serum E2 levels very similar to those seen during the first proestrus. By days 26-28, the profile of the LH surge was indistinguishable from that of the first preovulatory surge. Starting on day 26, and in addition to the LH surge elicited by the 48-h E2 pulse, an earlier surge occurred on the next day after E2 implantation. By day 30, the early LH surge became firmly established, and the late surge was no longer apparent. It is suggested that in the female rat, the development of E2-positive feedback comprises four phases: phase I, before day 16, in which the surge mechanism of the LH-releasing system is not developed; phase II, between days 16-20, in which E2 levels twice as high as those of first proestrus are necessary to activate the LH surge mechanism; phase III, which is initiated at the beginning of the juvenile period (approximately days 20-22) and in which the LH surge mechanism responds to E2 levels of preovulatory magnitude; and mechanism responds to E2 levels of preovulatory magnitude; and phase IV, which begins around days 26-28 and in which a 24-h exposure to E2 levels of preovulatory magnitude is sufficient to elicit a LH surge.

Plasma triiodothyronines in fetal sheep: effects of illness and thyroidectomy.

Plasma 3,5,3'-triiodothyronine (T3) and 3,3',5'-triiodothyronine concentrations were measured in fetal sheep prior to death in utero and after thyroidectomy. In six fetal sheep who subsequently died in utero, plasma rT3 concentrations were elevated in all for 2 to 13 days prior to death. There were no consistent changes in plasma T4 concentrations. In two thyroidectomized fetal sheep, plasma T4 and rT3 concentrations fell to low levels. Plasma T3 concentrations remained low and there was no increase in plasma T3 in the last week prior to parturition like that which occurs in normal fetal sheep. Parturition was preceded by the normal increase in fetal plasma cortisol concentrations and occurred at the normal time. These data indicate that plasma rT3 concentrations are increased as a result of illness in fetal sheep and that such measurements may be useful as an indicator of fetal distress. The normal increase in plasma T3 late in gestation is not necessary for the late gestational cortisol surge or for normal parturition.

Inhibition of Prolactin Release by a Thalidomide-Related Compound (CG 603)

CG 603 is a cyclic imide. Some cyclic amides like thalidomide are central nervous system depressants (1). Barbiturates block ovulation in the rat (2, 3), and recently this laboratory reported that a single injection of Na pentobarbital (Pb) at 1 pm on the day of proestrus prevented the pronounced rise in serum LH on the late afternoon of proestrus (4). Serum prolactin was elevated 30 min after the Pb injection, but the late afternoon surge of serum prolactin was blocked completely. It was of interest, therefore, to determine the effects of a single injection of CG 603 given on the early afternoon of the day of proestrus on serum prolactin levels.Materials and Methods. Mature, 3 to 4 month old virgin female Sprague-Dawley rats (Carworth Farms, Portage, MI), weighing 210-245 g each, were housed in a temperature controlled (25±1°) and artificially illuminated (lights on from 7 am to 9 pm daily) animal room. They were given Wayne Lab Blox pellets and water ad libitum. At least two consecutive estrous cycles w...