Techniques to determine ignition, flame stability and burnout of blended coals in p.f. power station boilers

The blending of coals has become popular to improve the performance of coals, to meet specifications of power plants and, to reduce the cost of coals, This article reviews the results and provides new information on ignition, flame stability, and carbon burnout studies of blended coals. The reviewed studies were conducted in laboratory-, pilot-, and full-scale facilities. The new information was taken in pilot-scale studies. The results generally show that blending a high-volatile coal with a low-volatile coal or anthracite can improve the ignition, flame stability and burnout of the blends. This paper discusses two general methods to predict the performance of blended coals: (1) experiment; and (2) indices. Laboratory- and pilot-scale tests, at least, provide a relative ranking of the combustion performance of coal/blends in power station boilers. Several indices, volatile matter content, heating value and a maceral index, can be used to predict the relative ranking of ignitability and flame stability of coals and blends. The maceral index, fuel ratio, and vitrinite reflectance can also be used to predict the absolute carbon burnout of coal and blends within limits. (C) 2000 Elsevier Science Ltd. All rights reserved.

Stability of nest range, home range and movement of the northern bettong (Bettongia tropica) following moderate-intensity fire in a tropical woodland, north-eastern Queensland

Nest use, home-range characteristics and nightly movements by the northern bettong (Bettongia tropica) were examined before and after a low- to moderate-intensity fire in sclerophyll woodland in north-eastern Australia using radio-telemetry. In all, 23 animals were radio-tracked at three-month intervals between February 1995 and May 1996. During November 1995 a low- intensity experimental fire burned the entire home range of most animals. The northern bettong appeared fairly catholic in choice of nest site, with a variety of nest locations and nesting materials used. Prior to the fire, nests were generally located in areas of dense cover, such as the skirts of grass trees (46%) or grass close to a log (29%). After fire removed most ground cover in the nesting areas of most animals, bettongs used remaining shelter such as boulder piles (45%), recently fallen trees (8%) and patches of unburnt vegetation (21%). Nest areas (10.1 ha) of males were significantly larger than those of females (5.4 ha). Home ranges of both sexes were large (59 ha) and most ranges lacked distinct core areas, suggesting that bettongs used all parts of their home ranges equally. High mean rates of nightly movement by the northern bettong indicated that large distances were moved within home ranges during nightly foraging. No significant fire-related changes were detected in home-range size, home-range location, nest-area location or mean rates of nightly movement, suggesting that the northern bettong is well adapted to the low- and medium-intensity fires that characterise its habitat.

Habitat complexity, spatial interference, and "minimum risk distribution": a framework for population stability

In the past century, the debate over whether or not density-dependent factors regulate populations has generally focused on changes in mean population density, ignoring the spatial variance around the mean as unimportant noise. In an attempt to provide a different framework for understanding population dynamics based on individual fitness, this paper discusses the crucial role of spatial variability itself on the stability of insect populations. The advantages of this method are the following: (1) it is founded on evolutionary principles rather than post hoc assumptions; (2) it erects hypotheses that can be tested; and (3) it links disparate ecological schools, including spatial dynamics, behavioral ecology, preference-performance, and plant apparency into an overall framework. At the core of this framework, habitat complexity governs insect spatial variance. which in turn determines population stability. First, the minimum risk distribution (MRD) is defined as the spatial distribution of individuals that results in the minimum number of premature deaths in a population given the distribution of mortality risk in the habitat (and, therefore, leading to maximized population growth). The greater the divergence of actual spatial patterns of individuals from the MRD, the greater the reduction of population growth and size from high, unstable levels. Then, based on extensive data from 29 populations of the processionary caterpillar, Ochrogaster lunifer, four steps are used to test the effect of habitat interference on population growth rates. (1) The costs (increasing the risk of scramble competition) and benefits (decreasing the risk of inverse density-dependent predation) of egg and larval aggregation are quantified. (2) These costs and benefits, along with the distribution of resources, are used to construct the MRD for each habitat. (3) The MRD is used as a benchmark against which the actual spatial pattern of individuals is compared. The degree of divergence of the actual spatial pattern from the MRD is quantified for each of the 29 habitats. (4) Finally, indices of habitat complexity are used to provide highly accurate predictions of spatial divergence from the MRD, showing that habitat interference reduces population growth rates from high, unstable levels. The reason for the divergence appears to be that high levels of background vegetation (vegetation other than host plants) interfere with female host-searching behavior. This leads to a spatial distribution of egg batches with high mortality risk, and therefore lower population growth. Knowledge of the MRD in other species should be a highly effective means of predicting trends in population dynamics. Species with high divergence between their actual spatial distribution and their MRD may display relatively stable dynamics at low population levels. In contrast, species with low divergence should experience high levels of intragenerational population growth leading to frequent habitat-wide outbreaks and unstable dynamics in the long term. Six hypotheses, erected under the framework of spatial interference, are discussed, and future tests are suggested.

Detection and stability of Japanese encephalitis virus RNA and virus viability in dead infected mosquitoes under different storage conditions

A semi-nested polymerase chain reaction (PCR) was evaluated for detection of Japanese encephalitis (JE) virus in infected mosquitoes stored under simulated northern Australian summer conditions. The effect of silica gel, thymol, and a combination of the two on RNA stability and virus viability in dead mosquitoes were also examined. While JE virus RNA was relatively stable in mosquitoes held for up to 14 days after death, viable virus was not detected after day 1. Thymol vapor inhibited fungal contamination. Detection of single mosquitoes infected with JE virus in large pools of mosquitoes was also investigated. Single laboratory-infected mosquitoes were detected in pools of less than or equal to200 mosquitoes and in pools diluted to 0.2/100 and 0.1/100 mosquitoes, using the semi-nested PCR. However, the ability to detect live virus decreased as pool size increased. The semi-nested PCR proved more expensive than virus isolation for pools of 100 mosquitoes. However, the semi-nested PCR was faster and more economical using larger pools. Results indicate that surveillance of JE virus in mosquitoes using the semi-nested PCR is an alternative to monitoring seroconversions in sentinel pigs.

Patterns of change and stability in the gender division of household labour in Australia, 1986-1997

Recent research in Australia and overseas has suggested that we are witnessing a convergence of men's and women's time on domestic labour activities. But there is disagreement about whether this is due to women reducing their time on housework or men increasing their time on housework. This article addresses these issues using national survey data collected in Australia in 1986, 1993 and 1997. The results show some changes in the proportional responsibilities of men and women in the home with men reporting a greater share of traditional indoor activities. But overall both men and women are spending less time on housework. In particular, women's time on housework has declined by six hours per week since 1986. Hence, while the gender gap between men's and women's involvement in the home is getting smaller, it is not the result of men increasing their share of the load, but is due to the large decline in women's time spent on domestic labour. There is also evidence of change in the relationship. between paid and unpaid work for women. Women's hours of,paid labour had a greater impact on their involvement in domestic labour in 1997 compared to a decade earlier. The article concludes that women's increased labour force involvement in combination with changing patterns and styles, of consumption is leading to some changes in the gender-division:of household labour, but not in the direction anticipated by earlier commentators on the domestic division of labour.

Resources for security and stability? The politics of regional cooperation on the Mekong, 1957-2001

This article tells about the relationship between resource politics and security in international relations. Using the Mekong River Basin as its case study, the article examines the place of resource and development issues in attempts to develop regional institutions. The question of whether a resource development regime with apparently low productivity in terms of technical output, but high levels of resilience and longevity, should be considered a failure or not, is considered. This question is examined within the broader context of Southeast Asian politics during the First, Second, and Third Indochina conflicts as well as the post-cold war era. The article argues that survival and a capacity to change to meet the challenges of extreme broader events are clear evidence of regime success. From this standpoint, the article explores ways in which the Mekong resource regime is linked to more general concerns for political security and stability and may in fact reflect political concerns for subregional neighborhood maintenance.

Quantification and stability of everolimus (SDZ RAD) in human blood by high-performance liquid chromatography-electrospray tandem mass spectrometry

We report here a validated method for the quantification of a new immunosuppressant drug, everolimus (SDZ RAD), using HPLC-tandem mass spectrometry. Whole blood samples (500 mul) were prepared by protein precipitation, followed by C-18 solid-phase extraction. Mass spectrometric detection was by selected reaction monitoring with an electrospray interface operating in positive ionization mode. The assay was linear from 0.5 to 100 mug/l (r(2) > 0.996, n = 9). The analytical recovery and inter-day imprecision, determined using whole blood quality control samples (n = 5) at 0.5, 1.2, 20.0, and 75.0 mug/l, was 100.3-105.4% and less than or equal to7.6%, respectively. The assay had a mean relative recovery of 94.8 +/- 3.8%. Extracted samples were stable for up to 24 h. Fortified everolimus blood samples were stable at -80 degreesC for at least 8 months and everolimus was found to be stable in blood when taken through at least three freeze-thaw cycles. The reported method provides accurate, precise and specific measurement of everolimus in blood over a wide analytical range and is currently supporting phase 11 and III clinical trials. (C) 2002 Elsevier Science B.V. All rights reserved.

Intraindividual allometric development of aerobic power in 8- to 16-year-old boys

Purpose: The aims of this study are two-fold: first, to analyze intraindividual allometric development of aerobic power of 73 boys followed at annual intervals from 8 to 16 yr, and second, to relate scaled aerobic power with level of habitual physical activity and biological maturity status. Methods: Peak (V) over dot O-2 (treadmill), height, and body mass were measured. Biological maturity was based on age at peak height velocity (PHV) and level of physical activity was based on five assessments between 11 and 15 yr and at 17 yr. Interindividual and intraindividual allometric coefficients were calculated. Multilevel modeling was applied to verify if maturity status and activity explain a significant proportion of peak (V) over dot O-2 after controlling for other explanatory characteristics. Results: At most age levels, interindividual allometry coefficients for body mass exceed k = 0.750. Intraindividual coefficients of peak (V) over dot O-2 by body mass vary widely and range from k' = 0,555 to k' = 1,178. Late maturing boys have smaller k' coefficients than early maturing boys. Conclusion: Peak (V) over dot O-2 is largely explained by body mass, but activity level and its interaction with maturity status contribute independently to peak (V) over dot O-2 even after adjusting for body mass.

Coexistence of stability and mobility in postural control: evidence from postural compensation for respiration

This study evaluated the extent to which movement of the lower limbs and pelvis may compensate for the disturbance to posture that results from respiratory movement of the thorax and abdomen. Motion of the neck, pelvis, leg and centre of pressure (COP) were recorded with high resolution in conjunction with electromyographic activity (EMG) of flexor and extensor muscles of the trunk and hip. Respiration was measured from ribcage motion. Subjects breathed quietly, and with increased volume due to hypercapnoca (as a result of breathing with increased dead-space) and a voluntary increase in respiration. Additional recordings were made during apnoea. The relationship between respiration and other parameters was measured from the correlation between data in the frequency domain (i.e. coherence) and from time-locked averages triggered from respiration. In quiet standing, small angular displacements (similar to0.5degrees) of the trunk and leg were identified in raw data. Correspondingly, there were peaks in the power spectra of the angular movements and EMG. While body movement and EMG were coherent with respiration (>0.5), the coherence between respiration and COP displacement was low (

Changes in postural stability in women aged 20 to 80 years

Background. A study of postural stability was undertaken to identify the relationship between vision and support surface across age decades. Understanding when reliance on vision for postural stability emerges and the support conditions contributing to this instability may provide the evidence required to introduce falls-prevention strategies in younger age decades. Methods. We measured postural stability in 453 women aged 20 to 80 years using the Balance Master force-plate system while the women performed the modified Clinical Test for the Sensory Interaction and Balance (firm and foam surfaces, eyes open and closed) and the Single-Limb Stance Test (eyes open and closed). Results. Women in their 60s and 70s were more unstable than younger women in bilateral stance on a firm surface with the eyes closed. This instability was evident from the 50s when a foam surface was introduced and from the 40s when single-limb stance was tested with eyes closed. A further decline in stability was demonstrated for each subsequent decade when the eyes were closed in single-limb stance. Conclusions. Age, visual condition, and support surface were significant variables influencing postural stability in women. Reliance on vision for postural stability was evident for women from the 40s when single-limb stance was tested, from the 50s when bilateral stance on foam was tested, and from the 60s when a firm surface was used. The cause(s) of this decline in stability requires further investigation, and screening for postural instability between the ages of 40 and 60 is advocated.

Stability of planar flames as gasdynamic discontinuities

The stability of a steadily propagating planar premixed flame has been the subject of numerous studies since Darrieus and Landau showed that in their model flames are unstable to perturbations of any wavelength. Moreover, the instability was shown to persist even for very small wavelengths, i.e. there was no high-wavenumber cutoff of the instability. In addition to the Darrieus-Landau instability, which results from thermal expansion, analysis of the diffusional thermal model indicates that premixed flames may exhibit cellular and pulsating instabilities as a consequence of preferential diffusion. However, no previous theory captured all the instabilities including a high-wavenumber cutoff for each. In Class, Matkowsky & Klimenko (2003) a unified theory is proposed which, in appropriate limits and under appropriate assumptions, recovers all the relevant previous theories. It also includes additional new terms, not present in previous theories. In the present paper we consider the stability of a uniformly propagating planar flame as a solution of the unified model. The results are then compared to those based on the models of Darrieus-Landau, Sivashinsky and Matalon-Matkowsky. In particular, it is shown that the unified model is the only model to capture the Darrieus-Landau, cellular and pulsating instabilities including a high-wavenumber cutoff for each.