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Critical Stage (critical + stage)
Selected AbstractsIdentification of Critical Stage for Disease Development and Biocontrol of Alternaria Blight of Indian Mustard (Brassica juncea)JOURNAL OF PHYTOPATHOLOGY, Issue 4 2004P. D. Meena Abstract Fungicides mancozeb and carbendazim caused 100% reduction in mycelial growth of Alternaria brassicae over control in vitro while 1% (w/v) aqueous bulb extract of Allium sativum and leaf extract of Acacia nilotica caused significant reductions. In dual culture, GR isolate of Trichoderma viride performed the best among the test isolates of Trichoderma, causing 81%, 82% reduction in mycelial growth of A. brassicae over control. Performance of isolates SI-2, P and SI-1 of T. viride were at par (P < 0.01) with that of GR isolate. Spraying of A. brassicae at different ages of the mustard host plant identified 75 days after sowing (d.a.s.) as the most critical age of the mustard plant for development of Alternaria blight severity on the crop with 45 d.a.s. being the next most important one. Mancozeb was the best among all the treatments, resulting in the lowest disease severity on leaves of mustard at both Sewar and Ludhavai as also the lowest A-value (area under disease progress curve). Performance of bulb extract of A. sativum in checking the disease severity on leaves and pods was at par (P,<,0.05) with mancozeb. The GR isolate of T. viride was at par with mancozeb in checking blight severity on mustard leaves at Sewar while performance of the bioagent was significantly (P,<,0.05) inferior to the chemical fungicide at Ludhavai. Performance of the bioagent isolate GR of T. viride in checking the disease severity on pods was at par (P < 0.05) with mancozeb at both Sewar and Ludhavai, the treatment recording the lowest A-value on pods. While application of bulb extract of A. sativum resulted in highest seed yield at Sewar in 2001,2002, the bioagent isolate GR of T. viride did so at Ludhavai, both the treatments being at par (P < 0.05) with mancozeb and significantly higher than control. Application of bulb extract of A. sativum at 45 and 75 d.a.s. resulted in lowest blight severity on leaves and pods as also in highest seed yield among the different single and combination of treatments. Although disease severity in the treatment was at par (P < 0.05) with that in mancozeb, application of the plant extract at the two stages of crop growth resulted in significantly higher seed yield compared with the two applications of the chemical fungicide. However, application of the treatments singly only at 75 d.a.s., GR isolate of T. viride at 45 and 75 d.a.s., A. sativum 45 d.a.s. + T. viride 75 d.a.s., and T. viride 45 d.a.s. + A. sativum 75 d.a.s. resulted in seed yield at par (P < 0.05) with application of bulb extract of A. sativum at 45 and 75 d.a.s. [source] Mechanical preparation of root canals: shaping goals, techniques and meansENDODONTIC TOPICS, Issue 1 2005Michael Hülsmann Preparation of root canal systems includes both enlargement and shaping of the complex endodontic space together with its disinfection. A variety of instruments and techniques have been developed and described for this critical stage of root canal treatment. Although many reports on root canal preparation can be found in the literature, definitive scientific evidence on the quality and clinical appropriateness of different instruments and techniques remains elusive. To a large extent this is because of methodological problems, making comparisons among different investigations difficult if not impossible. The first section of this paper discusses the main problems with the methodology of research relating to root canal preparation while the remaining section critically reviews current endodontic instruments and shaping techniques. [source] Visiting America: notes from an alcohol-focused study tour made in 1961ADDICTION, Issue 12 2008Griffith Edwards ABSTRACT Aims This paper has as its focus a study tour made by the author in 1961. Diary notes are used to capture a historical moment in the evolution of alcohol studies. The paper will argue for the continuing value today of such experiences in support of career development and the building of ,the field'. Data sources Diary notes and personal recollection. Findings The United States was at the time more active than the United Kingdom in its response to alcohol problems. There was, however, a disjunction between the elite American research world and the world of action, which was not informed greatly by research. For the most part, treatment services and prevention strategies seemed driven by opinion rather than by evidence. But at the level of serious scientific endeavour there was opportunity to meet influential figures including Seldon Bacon, Morris Chafetz, Milton Gross, Ebbe Curtis Hoff, Harris Isbell, E. M. Jellinek, Mark Keller, Benjamin Kissen, Robert Strauss, Wolf Schmidt and Abraham Wikler, who generously made their time available. Conclusions These diary notes provide a snapshot of a field of endeavour at a critical stage of transition from uninformed assumptions towards establishment of a research base which can inform public action. The visit was of tangible value to the visitor in several different identified ways. Such an experience is inevitably time-bound and personal, but there are general conclusions to be drawn as to the benefits which will be derived from early travel opportunities in a field such as alcohol studies, which is all too easily culture-bound in its horizons and assumptions. Alcohol science needs to be more reflective on its history and the mechanisms that help to make it happen. [source] Suspended sediment concentration and the ripple,dune transitionHYDROLOGICAL PROCESSES, Issue 17 2004Robert J. Schindler Abstract Flume experiments were conducted in order to monitor changes in flow turbulence intensity and suspended sediment concentration at seven stages across the ripple,dune transition and at three different positions above the bed surface. Three-dimensional velocity measurements were obtained using an acoustic Doppler velocimeter (ADV). Suspended sediment concentration (SSC) was monitored indirectly using ADV signal amplitude. Although limited to time-averaged parameters, the analysis reveals that SSC varies significantly with stage across the transition and with sampling height. The statistical analysis also reveals an apparent uniformity of suspended sediment concentration with height above the bed in the lower half of the flow depth at the critical stage in the transition from ripples to dunes. This is also the stage at which turbulence intensity is maximized. Statistically significant correlations were also observed between suspended sediment concentrations and root-mean-square values of vertical velocity fluctuations. These correlations reflect the various levels of shear-layer activity and the distinct turbulent flow regions across the transition. Conversely, time-averaged values of Reynolds shear stress exhibit a very weak relationship with suspended sediment concentrations. Copyright © 2004 John Wiley & Sons, Ltd. [source] Ultrasonic Investigation of the Effect of Vegetable Shortening and Mixing Time on the Mechanical Properties of Bread DoughJOURNAL OF FOOD SCIENCE, Issue 9 2009K.L. Mehta ABSTRACT:, Mixing is a critical stage in breadmaking since it controls gluten development and nucleation of gas bubbles in the dough. Bubbles affect the rheology of the dough and largely govern the quality of the final product. This study used ultrasound (at a frequency where it is sensitive to the presence of bubbles) to nondestructively examine dough properties as a function of mixing time in doughs prepared from strong red spring wheat flour with various amounts of shortening (0%, 2%, 4%, 8% flour weight basis). The doughs were mixed for various times at atmospheric pressure or under vacuum (to minimize bubble nucleation). Ultrasonic velocity and attenuation (nominally at 50 kHz) were measured in the dough, and dough density was measured independently from specific gravity determinations. Ultrasonic velocity decreased substantially as mixing time increased (and more bubbles were entrained) for all doughs mixed in air; for example, in doughs made without shortening, velocity decreased from 165 to 105 ms,1, although superimposed on this overall decrease was a peak in velocity at optimum mixing time. Changes in attenuation coefficient due to the addition of shortening were evident in both air-mixed and vacuum-mixed doughs, suggesting that ultrasound was sensitive to changes in the properties of the dough matrix during dough development and to plasticization of the gluten polymers by the shortening. Due to its ability to probe the effect of mixing times and ingredients on dough properties, ultrasound has the potential to be deployed as an online quality control tool in the baking industry. [source] Post-revolutionary State Building in Ethiopia, Iran and Nicaragua: Lessons from TerrorPOLITICAL STUDIES, Issue 5 2000Rosemary H. T. O'Kane This paper focuses on an earlier theorized critical stage of revolution, the Reign of Terror which is redefined with summary justice as its essence and employed in a comparative analysis of three modern revolutions, Ethiopia, Iran and Nicaragua. The analysis demonstrates the importance of national factors over international factors in explaining post-revolutionary state construction. A reign of terror is an extemporized state; it is not an inevitable stage of revolution. Comparison of Ethiopia and Iran, where terrors occurred, is contrasted with Nicaragua, where a reign of terror was avoided. This reveals the significance for post-revolutionary state construction of the timing and outcome of civil war, of domestic policy choices constrained by circumstances directly encountered and of state control over new, revolutionary, means of coercion. [source] The First Congress of Ethnozoological NomenclatureTHE JOURNAL OF THE ROYAL ANTHROPOLOGICAL INSTITUTE, Issue 2006Brent Berlin Folk names for fundamental ethnobiological categories have been shown to be governed by regular nomenclatural principles. Two principles at work in ethnozoological nomenclature , onomatopoeia and metaphorical description of some observable property of the organism , are fairly well established as the basis for naming many folk genera. A third but less understood principle is that associated with what has been called sound symbolism. In the languages of traditional peoples, semantically opaque names for animals often exhibit sound-symbolic properties that humans unconsciously recognize as capturing some aspect of the fundamental essence or nature of the creature being named. How is this to be explained, in spite of the changes that have taken place in human verbal communication since the beginnings of what one might call full-blown language? In what ways are these principles related to more general principles of natural classification based on shape and movement? If verbal mimesis represents a critical stage in the evolution of human cognition, what informed speculations can be brought to bear on what might be called the First Congress of Ethnozoological Nomenclature? [source] The mortality of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) neonate larvae in relation to drop-off and soil surface temperature: the dangers of bungy jumpingAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 4 2008David J Perovi Abstract The first larval instar has been identified as a critical stage for population mortality in Lepidoptera, yet due to the body size of these larvae, the factors that contribute to mortality under field conditions are still not clear. Dispersal behaviour has been suggested as a significant, but ignored factor contributing to mortality in first-instar lepidopteran larvae. The impact that leaving the host plant has on the mortality rate of Helicoverpa armigera neonates was examined in field crops and laboratory trials. In this study the following are examined: (1) the effects of soil surface temperature, and the level of shade within the crop, on the mortality of neonates on the soil after dropping off from the host plant; (2) the percentage of neonates that dropped off from a host plant and landed on the soil; and (3) the effects of exposure to different soil surface temperatures on the development and mortality of neonates. The findings of this study showed that: (1) on the soil, surface temperatures above 43°C were lethal for neonates, and exposure to these temperatures contributed greatly to the overall mortality rate observed; however, the fate of neonates on the soil varied significantly depending on canopy closure within the crop; (2) at least 15% of neonates dropped off from the host plant and landed on the soil, meaning that the proportion of neonates exposed to these condition is not trivial; and (3) 30 min exposure to soil surface temperatures approaching the lethal level (>43°C) has no significant negative effects on the development and mortality of larvae through to the second instar. Overall leaving the plant through drop-off contributes to first-instar mortality in crops with open canopies; however, survival of neonates that have lost contact with a host plant is possible, and becomes more likely later in the crop growing season. [source] Sequential developmental changes in holoprosencephalic mouse embryos exposed to ethanol during the gastrulation period,BIRTH DEFECTS RESEARCH, Issue 7 2007Daisuke Higashiyama Abstract BACKGROUND: Prenatal exposure to ethanol induces holoprosencephalic malformations in both humans and laboratory animals. However, its teratogenic window for inducing holoprosencephaly is narrow, and the teratogenic mechanism is not well understood. In the present study, we examined the morphological changes in the craniofacial structures of mouse embryos/fetuses at intervals following ethanol treatment and evaluated gene expression patterns in the embryos. METHODS: Pregnant C57BL/6J mice were given two doses of ethanol (30 mg/kg in total) on the morning (7:00 and 11:00 AM) of day 7. The fetuses were observed at E10.5 and E15.5 grossly and/or histologically. The expression of Shh and Nkx2.1 gene transcripts was examined at E8.5 by in situ hybridization. RESULTS: Gross and histological abnormalities of the brain and face were found in ethanol-exposed fetuses, and their midline structures were most frequently affected. The midline commissural fibers were often lacking in ethanol-exposed fetuses, even in those cases without external gross malformations. In situ hybridization revealed down-regulation of Shh and Nkx2.1 genes in ethanol-exposed embryos. CONCLUSIONS: The results indicate that ethanol may perturb the expression of some developmental genes at a critical stage of embryonic development and induce holoprosencephaly and other midline craniofacial malformations, including histological brain abnormalities. Birth Defects Research (Part A), 2007. © 2007 Wiley-Liss, Inc. [source] Community-Led Social Venture CreationENTREPRENEURSHIP THEORY AND PRACTICE, Issue 2 2007Helen Haugh The addition of new enterprises to the economy has long been considered essential to economic growth. The process of venture creation in the private sector has been heavily researched and frequently modeled, although few models explain the process of nonprofit enterprise creation. Nonprofit social ventures pursue economic, social, or environmental aims, generating at least part of their income from trading. They fill market gaps between private enterprise and public sector provision, and, increasingly, policy makers consider them to be valuable agents in social, economic, and environmental regeneration and renewal. This article presents findings from a qualitative study of the inception of five community-led nonprofit social ventures, producing a model of the stages of venture creation: (1) opportunity identification, (2) idea articulation, (3) idea ownership, (4) stakeholder mobilization, (5) opportunity exploitation, and (6) stakeholder reflection. A formal support network and a tailor-made support network are also part of the model, contributing resources to the new venture and assisting progression through the stages. The model highlights the resource acquisition and network creation that precede formal venture creation. In the nonprofit sector, these activities are undertaken by volunteers who do not have a controlling interest in the new venture. For practitioners, the model identifies critical stages in the process of community-led social venture creation and two areas where assistance is most needed: pre-venture business support and postcreating effective networks. [source] Rooting depth and soil moisture control Mediterranean woody seedling survival during droughtFUNCTIONAL ECOLOGY, Issue 3 2007F. M. PADILLA Summary 1Seedling survival is one of the most critical stages in a plant's life history, and is often reduced by drought and soil desiccation. It has been hypothesized that root systems accessing moist soil layers are critical for establishment, but very little is known about seedling root growth and traits in the field. 2We related seedling mortality to the presence of deep roots in a field experiment in which we monitored soil moisture, root growth and seedling survival in five Mediterranean woody species from the beginning of the growing season until the end of the drought season. 3We found strong positive relationships between survival and maximum rooting depth, as well as between survival and soil moisture. Species with roots in moist soil layers withstood prolonged drought better, whereas species with shallow roots died more frequently. In contrast, biomass allocation to roots was not related to establishment success. 4Access to moist soil horizons accounted for species-specific survival rates, whereas large root : shoot (R:S) ratios did not. The existence of soil moisture thresholds that control establishment provides insights into plant population dynamics in dry environments. [source] Geothermometry and geobarometry of overpressured environments in Qiongdongnan Basin, South China Sea,GEOFLUIDS (ELECTRONIC), Issue 3 2003Honghan Chen Abstract We demonstrate the use of PVT fluid inclusion modelling in the calculation of palaeofluid formation pressures, using samples from the YC21-1-1 and YC21-1-4 wells in the YC21-1 structural closure, Qiongdongnan Basin, South China Sea. Homogenisation temperatures and gas/liquid ratios were measured in aqueous fluid inclusions, and associated light hydrocarbon/CO2 -bearing inclusions, and their compositions were determined using a crushing technique. The vtflinc software was used to construct P,T phase diagrams that enabled derivation of the minimum trapping pressure for each order of fluid inclusion. Through the projection of average homogenisation temperatures (155, 185.5 and 204.5°C) for three orders of fluid inclusion on the thermal-burial history diagram of the Oligocene Yacheng and Lingshui formations, their trapping times were constrained at 4.3, 2.1 and 1.8 Ma, respectively. The formation pressure coefficient, the ratio of fluid pressure/hydrostatic pressure established by PVT modelling coupled with DST data, demonstrates that one and a half cycles of pressure increase,discharge developed in the Yacheng and Lingshui formations for about 4.3 Ma. In comparison, the residual formation pressure determined by 2D numerical modelling in the centre of LeDong depression shows two and a half pressure increase,discharge cycles for about 28 Ma. The two different methods suggest that a high fluid potential in the Oligocene reservoir of the YC21-1 structure developed at two critical stages for regional oil and natural gas migration and accumulation (5.8 and 2.0 Ma, respectively). Natural gas exploration in this area is therefore not advisable. [source] Kisspeptin/GPR54 system as potential target for endocrine disruption of reproductive development and functionINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2010M. Tena-Sempere Summary Kisspeptins, the products of Kiss1 gene acting via G protein-coupled receptor 54 (also termed Kiss1R), have recently emerged as essential gatekeepers of puberty onset and fertility. Compelling evidence has now documented that expression and function of hypothalamic Kiss1 system is sensitive not only to the activational effects but also to the organizing actions of sex steroids during critical stages of development. Thus, studies in rodents have demonstrated that early exposures to androgens and oestrogens are crucial for proper sexual differentiation of the patterns of Kiss1 mRNA expression, whereas the actions of oestrogen along puberty are essential for the rise of hypothalamic kisspeptins during this period. This physiological substrate provides the basis for potential endocrine disruption of reproductive maturation and function by xeno-steroids acting on the kisspeptin system. Indeed, inappropriate exposures to synthetic oestrogenic compounds during early critical periods in rodents persistently decreased hypothalamic Kiss1 mRNA levels and kisspeptin fibre density in discrete hypothalamic nuclei, along with altered gonadotropin secretion and/or gonadotropin-releasing hormone neuronal activation. The functional relevance of this phenomenon is stressed by the fact that exogenous kisspeptin was able to rescue defective gonadotropin secretion in oestrogenized animals. Furthermore, early exposures to the environmentally-relevant oestrogen, bisphenol-A, altered the hypothalamic expression of Kiss1/kisspeptin in rats and mice. Likewise, maternal exposure to a complex cocktail of endocrine disruptors has been recently shown to disturb foetal hypothalamic Kiss1 mRNA expression in sheep. As a whole, these data document the sensitivity of Kiss1 system to changes in sex steroid milieu during critical periods of sexual maturation, and strongly suggest that alterations of endogenous kisspeptin tone induced by inappropriate (early) exposures to environmental compounds with sex steroid activity might be mechanistically relevant for disruption of puberty onset and gonadotropin secretion later in life. The potential interaction of xeno-hormones with other environmental modulators (e.g., nutritional state) of the Kiss1 system warrants further investigation. [source] Mechanisms of exclusion of native coastal marsh plants by an invasive grassJOURNAL OF ECOLOGY, Issue 2 2006TODD E. MINCHINTON Summary 1Determining the mechanisms by which invasive species exclude natives is critical for conserving and restoring native populations in impacted habitats. In recent decades the grass Phragmites australis has been aggressively invading coastal marshes of North America, with monocultures often replacing diverse assemblages of plants. 2Our objective was to quantify how P. australis modifies the abiotic (soil and light conditions) and biotic (litter and shoots) environment and to determine the mechanisms by which it excludes two common forbs, the annual chenopod Atriplex patula var. hastata and the perennial aster Solidago sempervirens, from the highest tidal elevations of a brackish marsh in southern New England, USA. 3In a 3-year field experiment we added seeds of both forb species to stands of P. australis, where we manipulated shoots and litter in an orthogonal design, and to uninvaded marsh areas dominated by the rush Juncus gerardi, where we manipulated the shoots of the marsh vegetation. In general, seedling establishment and the number of plants surviving until the end of the growing season were substantially greater in areas not invaded by P. australis, and both shoots and litter limited the abundance of forbs within stands. 4Forbs surviving within stands of P. australis grew larger and produced more seeds than those in uninvaded areas, indicating that changes to the soil resulting from invasion do not preclude the survival of established forbs. This was confirmed by a glasshouse study where the performance of forbs in soil collected from within stands of P. australis was better than in soil from areas dominated by J. gerardi. 5Similar to many invasive grasses in terrestrial communities, P. australis excludes native forbs through competition, modifying the biotic environment of the marsh at both the ground (litter) and above-ground (shoots) levels. Our results suggest that successful invaders, such as P. australis, are likely to be the ones that can engineer habitats in multiple ways and limit populations of native species across several critical stages of their life history. [source] Growth patterns in adverse environmentsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2007Noël Cameron The triple-logistic pattern of human growth in linear dimensions is probably one of the most recognizable models within human biology. The fact that postnatal somatic growth occurs in three phases (infancy, childhood, adolescence) creates opportunities for the individual expression of this genetically directed, but environmentally modified, phenomenon. The impact of the environment works to alter the duration and intensity of critical stages within the total process resulting in individual patterns that can differ radically from the general pattern. However, the constancy of the general pattern is so fixed that its presence in children is taken as a reflection of good health. Departures from that pattern are recognized as reflecting ill health. While the cessation of growth in response to an acute attack is uniformly dramatic, the gradual response to chronic adverse stimuli is less easily predicted and interpreted. For example, in chronic scenarios the loss of centile position that precedes the eventual establishment of normal increments can be viewed as either a poor or a good growth response, as either maladaptive or adaptive, as either poor health or good health. This article reviews such growth patterns in urban South African children exploring the relationship between environment and growth outcome. Am. J. Hum. Biol., 2007. © 2007 Wiley-Liss, Inc. [source] Contrasting demographics of tropical savanna and temperate forest eucalypts provide insight into how savannas and forests function.AUSTRAL ECOLOGY, Issue 2 2009A case study using Corymbia clarksoniana from north-eastern Australia Abstract Eucalypts (Eucalyptus spp. and Corymbia spp.) dominate many communities across Australia, including frequently burnt tropical savannas and temperate forests, which receive less frequent but more intense fires. Understanding the demographic characteristics that allow related trees to persist in tropical savannas and temperate forest ecosystems can provide insight into how savannas and forests function, including grass,tree coexistence. This study reviews differences in critical stages in the life cycle of savanna and temperate forest eucalypts, especially in relation to fire. It adds to the limited data on tropical eucalypts, by evaluating the effect of fire regimes on the population biology of Corymbia clarksoniana, a tree that dominates some tropical savannas of north-eastern Australia. Corymbia clarksoniana displays similar demographic characteristics to other tropical savanna species, except that seedling emergence is enhanced when seed falls onto recently burnt ground during a high rainfall period. In contrast to many temperate forest eucalypts, tropical savanna eucalypts lack canopy-stored seed banks; time annual seed fall to coincide with the onset of predictable wet season rain; have very rare seedling emergence events, including a lack of mass germination after each fire; possess an abundant sapling bank; and every tropical eucalypt species has the ability to maintain canopy structure by epicormically resprouting after all but the most intense fires. The combination of poor seedling recruitment strategies, coupled with characteristics allowing long-term persistence of established plants, indicate tropical savanna eucalypts function through the persistence niche rather than the regeneration niche. The high rainfall-promoted seedling emergence of C. clarksoniana and the reduction of seedling survival and sapling growth by fire, support the predictions that grass,tree coexistence in savannas is governed by rainfall limiting tree seedling recruitment and regular fires limiting the growth of juvenile trees to the canopy. [source] Guidance on Safety/Health for Process Intensification Including MS Design.CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2010III: Risk Analysis Abstract The new technology of process intensification by multiscale equipment can significantly contribute to achieve a safer design by going from batch/semi-batch to continuous operation combined with a reduction of inventory of hazardous substances in critical stages. On the other hand, the shift to higher space-time-yields comprises new risks such as runaway reactions with hot spot formation, described in Part,I, and handling an explosive atmosphere in the presence of potential permanent ignition sources, described in Part,II. A tool was developed for preliminary risk assessments, called HAZOP-LIKE study, to cover the characteristic features of micro-designed equipment that are relatively unimportant when handling conventional equipment. Two generic cases concerning liquid/liquid and gas/gas reactions were studied to demonstrate the method. [source] | |||||||||||||||||||